WO2006016030A1 - Mechanochemical polishing composition, preparing and using method - Google Patents

Mechanochemical polishing composition, preparing and using method Download PDF

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Publication number
WO2006016030A1
WO2006016030A1 PCT/FR2005/001641 FR2005001641W WO2006016030A1 WO 2006016030 A1 WO2006016030 A1 WO 2006016030A1 FR 2005001641 W FR2005001641 W FR 2005001641W WO 2006016030 A1 WO2006016030 A1 WO 2006016030A1
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Prior art keywords
weight
composition
silica
ferric nitrate
composition according
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PCT/FR2005/001641
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French (fr)
Inventor
Georges Michel
Eric Dien
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Kemesys
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Classifications

    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09G—POLISHING COMPOSITIONS; SKI WAXES
    • C09G1/00—Polishing compositions
    • C09G1/02—Polishing compositions containing abrasives or grinding agents
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K3/00—Materials not provided for elsewhere
    • C09K3/14—Anti-slip materials; Abrasives
    • C09K3/1454—Abrasive powders, suspensions and pastes for polishing
    • C09K3/1463—Aqueous liquid suspensions
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
    • H01L21/3205—Deposition of non-insulating-, e.g. conductive- or resistive-, layers on insulating layers; After-treatment of these layers
    • H01L21/321—After treatment
    • H01L21/32115—Planarisation
    • H01L21/3212—Planarisation by chemical mechanical polishing [CMP]

Definitions

  • the present invention relates to a composition adapted to allow chemical mechanical polishing, more commonly known by the acronym CMP (of the English “Chemical-Mechanical-Polishing”).
  • It also relates to a process for preparing such a composition, as well as its use for polishing.
  • the invention relates, in its first aspect, a chemical mechanical polishing composition
  • a chemical mechanical polishing composition comprising a mixture of silica, ferric nitrate, nitric acid and water.
  • Such a composition in particular known to those skilled in the art by US Pat. No. 6,294,105, is typically used in the semiconductor industry to polish various materials deposited in layers on a substrate.
  • the perfectly flat surfaces obtained by this polishing serve as basic surfaces for the deposition of new layers of materials.
  • One of the essential characteristics of a polishing composition CMP is its selectivity, that is to say its ability to abrade at different speeds of materials of different natures, this selectivity being generally evaluated as a function of the respective abrasion speeds of a metal and an insulator in the case of semiconductors.
  • a certain approach is to seek a low selectivity, ie equivalent polishing rates on the upper layers, metals in the case of semiconductors, and on the lower layer, insulating material in the case of semiconductors.
  • a low selectivity polishing composition has a major disadvantage. It requires perfect control of the polishing times in order to avoid excessive thinning of the lower layer and degradation of the characteristics of the capacitor in the case of semiconductors.
  • the aim of the invention is to remedy this drawback by proposing a composition whose selectivity, ie the ratio of the polishing speeds on the upper layers to the polishing rates on the lower layers, is relatively high, typically greater than to 10.
  • the composition of the invention is essentially characterized in that the silica is a fumed silica whose average aggregate particle size in suspension is between 50 nm and 200 nm, and preferably between 120 nm and 160 nm.
  • the average particle size in suspension corresponds to the average diameter of the aggregated silica particles in the composition of the invention.
  • the fumed silica is an amorphous silica powder, or silicon oxide (SiC> 2), produced by hydrolysis of a chlorinated derivative of silicon, and comprising elementary particles of the order of 10 nm, which, at the dry state, associate in aggregates whose size is between 100 nm and 500 nm and which, in suspension, are in the form of aggregated particles whose size is smaller than that of aggregates in the dry state following the breaking them during the dispersion of the silica powder to obtain the composition of the invention.
  • the average particle size is obtained by mathematical calculation from the measurement, by photon correlation spectroscopy, of an intensity of light scattered through a sample of the composition of the invention as a function of time.
  • the composition of the invention makes it possible to obtain a metal removal rate substantially greater than that of the insulating material, it has excellent stability over time. Indeed, the particles it contains remain in suspension for a minimum of six months.
  • the pH is also invariable for a year or more. Thanks to this stability, the composition of the invention can be prepared industrially, well in advance, to be ready for use, which gives it great ease of use and saves considerable time for the application. polishing operation.
  • the composition of the invention advantageously comprises between 5% and 15% by weight of fumed silica, between 0.5% and 3% by weight of ferric nitrate and between 0.1% and 0.5% by weight of nitric acid.
  • the composition comprises 10% by weight of fumed silica, 1.67% by weight of ferric nitrate and between 0.2% and 0.5% by weight of nitric acid.
  • the cost of producing the composition of the invention is reduced by the use of reduced quantities of the most noble products entering into the composition of the mixture.
  • the fumed silica is a powder whose aggregates have a BET specific surface area of between 90 m 2 / g and 300 m 2 / g, and preferably of the order of 130 m 2 / g. .
  • the composition according to the invention comprises nitric acid in an amount to adjust its pH between 1.2 and 2, preferably 1.35.
  • the ferric nitrate may be ferric nitrate nonahydrate and / or the water may be deionized water.
  • deionized water water free of metal ions such as sodium, potassium, magnesium and calcium. Its use allows the contamination of the polishing composition in alkaline and alkaline earth elements to be residual.
  • Another object of the invention is a process for the preparation of the composition as described above.
  • this process comprises the following steps: a) Initially, dispersing the fumed silica in a nitric acid solution to obtain a silica concentration of between 15% and 30% by weight; b) In a second step, addition of a ferric nitrate solution to the dispersion obtained in the preceding step in order to obtain a silica concentration of between 5% and 15% by weight.
  • the invention finally relates to the use of the composition as described above for the chemical mechanical polishing of layers applied to a substrate carrying at least one micro-semiconductor component.
  • the substrate may be covered with a metal layer, said metal layer comprising, for example, tungsten, and / or a layer of insulating material, said insulating material comprising, for example, silicon oxide, and or at least one adhesion layer, said layer comprising, for example, titanium and / or titanium nitride.
  • Figure 1 is a schematic sectional view of a microcircuit before polishing.
  • Figure 2 is a schematic sectional view of a microcircuit after polishing by means of a particular composition according to the invention.
  • FIG. 1 shows the structure to be polished, defined on a silicon substrate with a diameter of 200 mm, in the test carried out.
  • the insulating material is on a support layer 1 constituted in the embodiment of silicon.
  • the oxidation of this support layer 1 allows the formation of the layer 2 of insulating material, which therefore comprises in the test of silicon oxide.
  • This layer 2 of insulating material is then etched with patterns 3.
  • two layers of adhesion 4 and 5 each of 200 ⁇ thickness are deposited: a first layer 4 of titanium and a second layer 5 of titanium nitride.
  • a layer 4 of titanium and a second layer 5 of titanium nitride.
  • the metal layer 6 consists of tungsten.
  • a composition according to the invention is prepared as follows for polishing the substrate of FIG.
  • the pyrogenic silica powder SiO 2 is dispersed in an oxidizing solution of nitric acid HNO 3 for the preparation of a homogeneous and stable suspension concentrated to 15% by weight of silica.
  • nitric acid and ferric nitrate nonahydrate solutions used in the above process are prepared from deionized water in order to limit contamination of the polishing composition into metal ions.
  • the mean diameter by volume of the particles, obtained by measurement according to the photon correlation spectroscopy technique, is between 125 nm and 150 nm;
  • the pH is 1.35;
  • the dynamic viscosity is equal to 2.5 centipoise
  • the pH shows a variation of less than 0.1 unit at the end of a year in summer.
  • the polishing composition is perfectly stable for at least 6 months, the minimum period during which the particles remain in suspension.
  • composition described above is used for polishing a microcircuit as shown in FIG.
  • the apparatus used is an orbital polishing platform comprising a semi-rigid mat consisting of polyester fibers coated with polyurethane and characterized by an x-y grid-like imprint as well as perforations in the thickness of the material.
  • the polishing composition is provided in an amount of the order of 300 mL.
  • the selectivity that is to say the ratio of the tungsten / silicon oxide removal rates, obtained during these different tests is 30.
  • the difference in the behavior of the different layers with respect to the polishing facilitates the detection of the end of polishing, the polishing being completed when the layer of insulating material appears on the surface and the detection is done by measuring the difference. coefficient of friction according to the layers exposed to polishing.
  • the rate of removal of the insulating material is low, the layer of insulating material is insensitive to a too long polishing time.
  • the rate of removal of tungsten RR is not zero. It is therefore possible to polish the tungsten layer at very low pressure.
  • the low value of the parameter a means that the sensitivity of the tungsten removal rate with respect to the pressure and the speed of rotation is reduced.
  • the method shows good reproducibility since it is insensitive to the drifts of the parameters of the machine, such as the drifts of the pressure and / or the speed of rotation of the plate.
  • the excellent reproducibility of the method employing the composition described above is also confirmed by a plate-to-plate non-uniformity parameter of less than 1% on 10 plates.
  • This parameter is the standard deviation of the removal rates for a series of values obtained under equivalent process conditions, divided by the average value of the removal rate on that same series, and multiplied by 100.
  • the selectivity obtained with the composition according to the invention is increasing when the rotational speed of the polisher plate and / or the pressure applied to the substrate to be polished are decreasing, for very low values of the speed of rotation and / or the pressure.

Abstract

The invention relates to a mechanochemical polishing composition comprising a silica, ferric nitrate, nitric acid and water mixture. According to said invention, the silica is embodied in the form of fumed silica whose particle mean size greeted in suspension ranges from 50 to 200nm, preferably from 120 to 160 nm. A method for preparing and using the inventive composition is also disclosed.

Description

Composition de polissage mécano chimique, procédé de préparation, et utilisation. Chemical mechanical polishing composition, method of preparation, and use
La présente invention concerne une composition adaptée à permettre un polissage mécano chimique, plus communément connu sous l'acronyme CMP (de l'anglais « Chemical-Mechanical-Polishing ») .The present invention relates to a composition adapted to allow chemical mechanical polishing, more commonly known by the acronym CMP (of the English "Chemical-Mechanical-Polishing").
Elle concerne également un procédé de préparation d'une telle composition, ainsi que son utilisation pour le polissage.It also relates to a process for preparing such a composition, as well as its use for polishing.
Plus précisément, l'invention concerne, selon son premier aspect, une composition de polissage mécano chimique comprenant un mélange de silice, de nitrate ferrique, d'acide nitrique et d'eau.More specifically, the invention relates, in its first aspect, a chemical mechanical polishing composition comprising a mixture of silica, ferric nitrate, nitric acid and water.
Une telle composition, notamment connue de l'homme du métier par le brevet US 6 294 105, est typiquement utilisée dans l'industrie des semi¬ conducteurs pour polir différents matériaux déposés en couches sur un substrat. Les surfaces parfaitement planes obtenues par ce polissage servent de surfaces de base pour le dépôt de nouvelles couches de matériaux.Such a composition, in particular known to those skilled in the art by US Pat. No. 6,294,105, is typically used in the semiconductor industry to polish various materials deposited in layers on a substrate. The perfectly flat surfaces obtained by this polishing serve as basic surfaces for the deposition of new layers of materials.
Une des caractéristiques essentielles d'une composition de polissage CMP est sa sélectivité, c'est-à- dire sa capacité à abraser à des vitesses différentes des matériaux de natures différentes, cette sélectivité étant généralement évaluée en fonction des vitesses respectives d'abrasion d'un métal et d'un isolant dans le cas des semi-conducteurs. Une certaine approche consiste à rechercher une sélectivité faible, c'est-à-dire des vitesses de polissage équivalentes sur les couches supérieures, de métaux dans le cas des semi-conducteurs, et sur la couche inférieure, de matériau isolant dans le cas des semi- conducteurs.One of the essential characteristics of a polishing composition CMP is its selectivity, that is to say its ability to abrade at different speeds of materials of different natures, this selectivity being generally evaluated as a function of the respective abrasion speeds of a metal and an insulator in the case of semiconductors. A certain approach is to seek a low selectivity, ie equivalent polishing rates on the upper layers, metals in the case of semiconductors, and on the lower layer, insulating material in the case of semiconductors.
C'est le cas du brevet US 6 294 105 précédemment évoqué, qui décrit une composition caractérisée par des rapports de vitesses (Â/min) d'enlèvement tungstène/matériau isolant de 2850/1625 à 2475/1050, c'est-à-dire dotée d'une sélectivité inférieure à 2,5.This is the case of US Pat. No. 6,294,105 previously mentioned, which describes a composition characterized by gear ratios (λ / min) of removal. tungsten / insulating material from 2850/1625 to 2475/1050, that is to say with a selectivity of less than 2.5.
Une composition de polissage de faible sélectivité présente un inconvénient majeur. Elle nécessite un parfait contrôle des temps de polissage afin d'éviter un amincissement excessif de la couche inférieure et la dégradation des caractéristiques du condensateur dans le cas des semi-conducteurs.A low selectivity polishing composition has a major disadvantage. It requires perfect control of the polishing times in order to avoid excessive thinning of the lower layer and degradation of the characteristics of the capacitor in the case of semiconductors.
L'invention vise à remédier à cet inconvénient en proposant une composition dont la sélectivité, c'est-à- dire le rapport des vitesses de polissage sur les couches supérieures sur les vitesses de polissage sur les couches inférieures, soit relativement élevée, typiquement supérieure à 10. A cette fin, la composition de l'invention, par ailleurs conforme à la définition générique qu'en donne le préambule ci-dessus, est essentiellement caractérisée en ce que la silice est une silice pyrogénée dont la taille moyenne de particule agrégée en suspension est comprise entre 50 nm et 200 nm, et de préférence entre 120 nm et 160 nm.The aim of the invention is to remedy this drawback by proposing a composition whose selectivity, ie the ratio of the polishing speeds on the upper layers to the polishing rates on the lower layers, is relatively high, typically greater than to 10. For this purpose, the composition of the invention, furthermore in conformity with the generic definition given in the preamble above, is essentially characterized in that the silica is a fumed silica whose average aggregate particle size in suspension is between 50 nm and 200 nm, and preferably between 120 nm and 160 nm.
La taille moyenne de particule agrégée en suspension correspond au diamètre moyen des particules agrégées de silice dans la composition de l'invention. En effet, la silice pyrogénée est une poudre amorphe de silice, ou oxyde de silicium (SiC>2) , produite par hydrolyse d'un dérivé chloré du silicium, et comprenant des particules élémentaires de l'ordre de 10 nm, qui, à l'état sec, s'associent en agrégats dont la taille est comprise entre 100 nm et 500 nm et qui, en suspension, se trouvent sous forme de particules agrégées dont la taille est inférieure à celle des agrégats à l'état sec suite au cassage de ceux-ci lors de la dispersion de la poudre de silice pour obtenir la composition de l'invention. La taille moyenne de particule est obtenue par calcul mathématique à partir de la mesure, par spectroscopie de corrélation de photons, d'une intensité de lumière diffusée à travers un échantillon de la composition de l'invention en fonction du temps.The average particle size in suspension corresponds to the average diameter of the aggregated silica particles in the composition of the invention. Indeed, the fumed silica is an amorphous silica powder, or silicon oxide (SiC> 2), produced by hydrolysis of a chlorinated derivative of silicon, and comprising elementary particles of the order of 10 nm, which, at the dry state, associate in aggregates whose size is between 100 nm and 500 nm and which, in suspension, are in the form of aggregated particles whose size is smaller than that of aggregates in the dry state following the breaking them during the dispersion of the silica powder to obtain the composition of the invention. The average particle size is obtained by mathematical calculation from the measurement, by photon correlation spectroscopy, of an intensity of light scattered through a sample of the composition of the invention as a function of time.
Outre le fait que la composition de l'invention permet d'obtenir une vitesse d'enlèvement du métal sensiblement plus importante que celle du matériau isolant, elle présente une excellente stabilité dans le temps. En effet, les particules qu'elle contient restent en suspension pendant une durée minimale de six mois. Le pH est également invariable pendant un an et plus. Grâce à cette stabilité, la composition de l'invention peut être préparée industriellement, longtemps à l'avance, pour être prête à l'emploi, ce qui lui confère une grande facilité d'utilisation et permet un gain de temps considérable pour l'opération de polissage.In addition to the fact that the composition of the invention makes it possible to obtain a metal removal rate substantially greater than that of the insulating material, it has excellent stability over time. Indeed, the particles it contains remain in suspension for a minimum of six months. The pH is also invariable for a year or more. Thanks to this stability, the composition of the invention can be prepared industrially, well in advance, to be ready for use, which gives it great ease of use and saves considerable time for the application. polishing operation.
La composition de l'invention comprend avantageusement entre 5% et 15% en poids de silice pyrogénée, entre 0,5% et 3% en poids de nitrate ferrique et entre 0,1% et 0,5% en poids d'acide nitrique. Selon un mode de réalisation préféré de l'invention, la composition comprend 10% en poids de silice pyrogénée, 1,67% en poids de nitrate ferrique et entre 0,2% et 0,5% en poids d'acide nitrique.The composition of the invention advantageously comprises between 5% and 15% by weight of fumed silica, between 0.5% and 3% by weight of ferric nitrate and between 0.1% and 0.5% by weight of nitric acid. . According to a preferred embodiment of the invention, the composition comprises 10% by weight of fumed silica, 1.67% by weight of ferric nitrate and between 0.2% and 0.5% by weight of nitric acid.
Par rapport à la composition décrite dans le document US 6 294 105, le coût de réalisation de la composition de l'invention est diminué par la mise en jeu de quantités réduites des produits les plus nobles rentrant dans la composition du mélange.With respect to the composition described in document US Pat. No. 6,294,105, the cost of producing the composition of the invention is reduced by the use of reduced quantities of the most noble products entering into the composition of the mixture.
Dans une version avantageuse de l'invention, la silice pyrogénée est une poudre dont les agrégats possèdent une surface spécifique BET comprise entre 90 m2/g et 300 m2/g, et de préférence de l'ordre de 130 m2/g.In an advantageous version of the invention, the fumed silica is a powder whose aggregates have a BET specific surface area of between 90 m 2 / g and 300 m 2 / g, and preferably of the order of 130 m 2 / g. .
La surface spécifique a été mesurée selon la technique Brunauer, Emmett, Teller (BET) . Par exemple, la composition selon l'invention comprend de l'acide nitrique en une quantité permettant d'ajuster son pH entre 1,2 et 2, de préférence à 1,35. Selon l'invention, le nitrate ferrique peut être le nitrate ferrique nonahydrate et/ou l'eau peut être de l'eau déionisée.The specific surface area was measured according to the Brunauer, Emmett, Teller (BET) technique. For example, the composition according to the invention comprises nitric acid in an amount to adjust its pH between 1.2 and 2, preferably 1.35. According to the invention, the ferric nitrate may be ferric nitrate nonahydrate and / or the water may be deionized water.
On entend par eau déionisée une eau dépourvue d'ions métalliques tels que le sodium, le potassium, le magnésium et le calcium. Son utilisation permet que la contamination de la composition de polissage en éléments alcalins et alcalino-terreux soit résiduelle.By deionized water is meant water free of metal ions such as sodium, potassium, magnesium and calcium. Its use allows the contamination of the polishing composition in alkaline and alkaline earth elements to be residual.
Un autre objet de l'invention est un procédé de préparation de la composition telle que décrite ci- dessus.Another object of the invention is a process for the preparation of the composition as described above.
Selon l'invention, ce procédé comprend les étapes suivantes : a) Dans un premier temps, dispersion de la silice pyrogénée dans une solution d'acide nitrique pour obtenir une concentration en silice comprise entre 15% et 30% en poids ; b) Dans un deuxième temps, addition d'une solution de nitrate ferrique à la dispersion obtenue à l'étape précédente afin d'obtenir une concentration en silice comprise entre 5% et 15% en poids.According to the invention, this process comprises the following steps: a) Initially, dispersing the fumed silica in a nitric acid solution to obtain a silica concentration of between 15% and 30% by weight; b) In a second step, addition of a ferric nitrate solution to the dispersion obtained in the preceding step in order to obtain a silica concentration of between 5% and 15% by weight.
L'invention a enfin pour objet l'utilisation de la composition telle que décrite ci-dessus pour le polissage mécano chimique de couches appliquées sur un substrat portant au moins un micro composant semi¬ conducteur.The invention finally relates to the use of the composition as described above for the chemical mechanical polishing of layers applied to a substrate carrying at least one micro-semiconductor component.
Selon l'invention, le substrat peut être recouvert d'une couche métallique, ladite couche métallique comprenant par exemple du tungstène, et/ou d'une couche de matériau isolant, ledit matériau isolant comprenant par exemple de l'oxyde de silicium, et/ou d'au moins une couche d'adhérence, ladite couche comprenant par exemple du titane et/ou du nitrure de titane.According to the invention, the substrate may be covered with a metal layer, said metal layer comprising, for example, tungsten, and / or a layer of insulating material, said insulating material comprising, for example, silicon oxide, and or at least one adhesion layer, said layer comprising, for example, titanium and / or titanium nitride.
D'autres avantages et particularités de l'invention apparaîtront à la lecture de la description détaillée qui en est faite ci-après, à titre indicatif et nullement limitatif, en référence aux dessins annexés dans lesquels : - la figure 1 est une vue schématique en coupe d'un microcircuit avant polissage. la figure 2 est une vue schématique en coupe d'un microcircuit après polissage au moyen d'une composition particulière conforme à l'invention.Other advantages and particularities of the invention will appear on reading the detailed description which is given hereinafter, by way of indication and in no way limiting, with reference to the appended drawings in which: - Figure 1 is a schematic sectional view of a microcircuit before polishing. Figure 2 is a schematic sectional view of a microcircuit after polishing by means of a particular composition according to the invention.
La figure 1 montre la structure à polir, définie sur un substrat de silicium de diamètre égal à 200 mm, dans l'essai réalisé. Le matériau isolant se trouve sur une couche support 1 constituée, dans l'exemple de réalisation, de silicium. L'oxydation de cette couche support 1 permet la formation de la couche 2 de matériau isolant, qui comprend donc dans l'essai de l'oxyde de silicium. Cette couche 2 de matériau isolant est gravée ensuite de motifs 3. Dans l'exemple traité, deux couches d'adhérence 4 et 5 de 200 Â d'épaisseur chacune sont ensuite déposées : une première couche 4 de titane et une seconde couche 5 de nitrure de titane. Enfin, une coucheFIG. 1 shows the structure to be polished, defined on a silicon substrate with a diameter of 200 mm, in the test carried out. The insulating material is on a support layer 1 constituted in the embodiment of silicon. The oxidation of this support layer 1 allows the formation of the layer 2 of insulating material, which therefore comprises in the test of silicon oxide. This layer 2 of insulating material is then etched with patterns 3. In the example treated, two layers of adhesion 4 and 5 each of 200 Å thickness are deposited: a first layer 4 of titanium and a second layer 5 of titanium nitride. Finally, a layer
6 métallique de 6000 Â d'épaisseur est déposée. Dans l'essai réalisé, la couche 6 métallique est constituée de tungstène.6 metal of 6000 Å thickness is deposited. In the test carried out, the metal layer 6 consists of tungsten.
Une composition selon l'invention est préparée comme suit pour le polissage du substrat de la figure 1.A composition according to the invention is prepared as follows for polishing the substrate of FIG.
Dans un premier réacteur, on opère une dispersion de la poudre de silice Siθ2 pyrogénée dans une solution oxydante d'acide nitrique HNO3 pour la préparation d'une suspension homogène et stable concentrée à 15% en poids de silice.In a first reactor, the pyrogenic silica powder SiO 2 is dispersed in an oxidizing solution of nitric acid HNO 3 for the preparation of a homogeneous and stable suspension concentrated to 15% by weight of silica.
Puis, dans un deuxième réacteur, on ajoute une solution de nitrate ferrique nonahydrate Fe (NO3) 3, 9H2O sur la dispersion précédente pour obtenir la composition présentée dans le tableau ci-dessous.Then, in a second reactor, a solution of ferric nitrate nonahydrate Fe (NO 3) 3, 9H 2 O to the previous dispersion to obtain the composition shown in the table below.
Les solutions d'acide nitrique et de nitrate ferrique nonahydrate utilisées dans le procédé ci-dessus sont préparées à partir d'eau déionisée, ceci afin de limiter la contamination de la composition de polissage en ions métalliques.The nitric acid and ferric nitrate nonahydrate solutions used in the above process are prepared from deionized water in order to limit contamination of the polishing composition into metal ions.
La composition massique obtenue par ce procédé est présentée dans le tableau suivant.
Figure imgf000007_0001
The mass composition obtained by this method is presented in the following table.
Figure imgf000007_0001
Les caractéristiques physico-chimiques de la composition obtenue dans le deuxième réacteur décrite ci- dessus sont les suivantes :The physico-chemical characteristics of the composition obtained in the second reactor described above are as follows:
• le diamètre moyen en volume des particules, obtenu par mesure selon la technique de spectroscopie de corrélation de photons, est compris entre 125 nm et 150 nm ; • le pH est égal à 1,35 ;The mean diameter by volume of the particles, obtained by measurement according to the photon correlation spectroscopy technique, is between 125 nm and 150 nm; The pH is 1.35;
• la viscosité dynamique est égale à 2,5 centipoises ;The dynamic viscosity is equal to 2.5 centipoise;
• la densité est égale à 1, 04 ;• the density is equal to 1, 04;
• la contamination en éléments alcalins et alcalino-terreux est inférieure à 10 ppm.• Contamination in alkaline and alkaline earth elements is less than 10 ppm.
Grâce à ces caractéristiques, le pH présente une variation de moins de 0,1 unité au bout d'une année en fut. La composition de polissage est parfaitement stable pendant au moins 6 mois, période minimale pendant laquelle les particules restent en suspension.Thanks to these characteristics, the pH shows a variation of less than 0.1 unit at the end of a year in summer. The polishing composition is perfectly stable for at least 6 months, the minimum period during which the particles remain in suspension.
La composition décrite précédemment est utilisée pour le polissage d'un microcircuit tel que représenté sur la figure 1.The composition described above is used for polishing a microcircuit as shown in FIG.
L'appareil utilisé est une plateforme de polissage orbitalaire comprenant un tapis semi-rigide constitué de fibres polyester enrobées de polyuréthane et caractérisé par une empreinte de type quadrillage x-y ainsi que par des perforations dans l'épaisseur du matériau. La composition de polissage est fournie en une quantité de l'ordre de 300 mL.The apparatus used is an orbital polishing platform comprising a semi-rigid mat consisting of polyester fibers coated with polyurethane and characterized by an x-y grid-like imprint as well as perforations in the thickness of the material. The polishing composition is provided in an amount of the order of 300 mL.
Comme représenté à la figure 2, après polissage, on obtient une surface 7 du microcircuit plane. Les dépôts métalliques ont été polis jusqu'à atteindre le niveau isolant et révéler les interconnexions conductrices 8. Le test de polissage a été effectué plusieurs fois. On observe en particulier que la vitesse (Â/min) d'enlèvement du tungstène est fonction de la pression appliquée en bar et de la vitesse de rotation du plateau de la polisseuse exprimée en tours/min. Le tableau ci-dessous rassemble les mesures de vitesse d'enlèvement obtenue.As shown in FIG. 2, after polishing, a surface 7 of the planar microcircuit is obtained. The metal deposits have been polished to the insulating level and reveal the conductive interconnections 8. The polishing test was carried out several times. In particular, it is observed that the rate (λ / min) of removal of the tungsten is a function of the pressure applied in bar and the speed of rotation of the plate of the polisher expressed in revolutions / min. The table below gathers the measurements of the speed of removal obtained.
Figure imgf000008_0001
Figure imgf000008_0001
La sélectivité, c'est-à-dire le rapport des vitesses d'enlèvement tungstène/oxyde de silicium, obtenue lors de ces différents tests est de 30.The selectivity, that is to say the ratio of the tungsten / silicon oxide removal rates, obtained during these different tests is 30.
Une telle sélectivité est avantageuse. En effet, la différence de comportement des différentes couches vis-à-vis du polissage facilite la détection de la fin du polissage, le polissage étant terminé lorsque la couche de matériau isolant apparaît en surface et la détection se faisant par la mesure de la différence de coefficient de friction selon les couches exposées au polissage. De plus, la vitesse d'enlèvement du matériau isolant étant faible, la couche de matériau isolant est peu sensible à un temps de polissage trop long.Such selectivity is advantageous. Indeed, the difference in the behavior of the different layers with respect to the polishing facilitates the detection of the end of polishing, the polishing being completed when the layer of insulating material appears on the surface and the detection is done by measuring the difference. coefficient of friction according to the layers exposed to polishing. In addition, since the rate of removal of the insulating material is low, the layer of insulating material is insensitive to a too long polishing time.
L' analyse des résultats démontre que le comportement de la composition en polissage est non prestonien. En effet, dans les conditions opératoires du test réalisé, la composition de polissage ne répond pas à la loi de Preston RR = a* (P*V) où RR est la vitesse d'enlèvement du tungstène en Â/min, a est un paramètre obtenu expérimentalement, P est la pression appliquée sur le substrat à polir en bar, et V est la vitesse de rotation du plateau de la polisseuse en tours/min. La relation entre la vitesse d'enlèvement RR et le facteur pression*vitesse P*V est du type RR = a*(P*V)+b dans l'The analysis of the results demonstrates that the behavior of the polishing composition is non-Prestonian. In fact, under the operating conditions of the test carried out, the polishing composition does not respond to Preston's law RR = a * (P * V) where RR is the rate of removal of tungsten in λ / min, a is a parameter obtained experimentally, P is the pressure applied to the substrate to be polished in bar, and V is the speed of rotation of the plate of the polisher in revolutions / min. The relation between the RR removal rate and the pressure-velocity factor P * V is of the type RR = a * (P * V) + b in the
laquelle b est un paramètre obtenu expérimentalement et est différent de zéro et RR, a, P et V sont tels que définis ci-dessus.which b is a parameter obtained experimentally and is different from zero and RR, a, P and V are as defined above.
Les valeurs des paramètres a et b pour la composition selon invention ont été déterminés sur la base de dix tests de polissage en faisant varier la pression appliquée sur le substrat et/ou la vitesse de rotation du plateau. Ainsi, la relation obtenue est la suivante : RR = 8,93* (P*V)+2300 dans laquelle RR, P et V sont tels que définis précédemment.The values of the parameters a and b for the composition according to the invention were determined on the basis of ten polishing tests by varying the pressure applied on the substrate and / or the speed of rotation of the plate. Thus, the relation obtained is as follows: RR = 8.93 * (P * V) + 2300 in which RR, P and V are as defined previously.
Par conséquent, pour des valeurs très faibles de la pression P appliquée au substrat à polir, la vitesse d'enlèvement du tungstène RR n'est pas nulle. Il est donc possible de polir la couche de tungstène à très basse pression.Therefore, for very low values of the pressure P applied to the substrate to be polished, the rate of removal of tungsten RR is not zero. It is therefore possible to polish the tungsten layer at very low pressure.
D'autre part, la faible valeur du paramètre a signifie que la sensibilité de la vitesse d'enlèvement du tungstène vis-à-vis de la pression et de la vitesse de rotation est réduite. Autrement dit, le procédé montre une bonne reproductibilité puisqu'il est peu sensible aux dérives des paramètres de la machine, comme les dérives de la pression et/ou de la vitesse de rotation du plateau.On the other hand, the low value of the parameter a means that the sensitivity of the tungsten removal rate with respect to the pressure and the speed of rotation is reduced. In other words, the method shows good reproducibility since it is insensitive to the drifts of the parameters of the machine, such as the drifts of the pressure and / or the speed of rotation of the plate.
L'excellente reproductibilité du procédé mettant en œuvre la composition décrite précédemment est également confirmée par un paramètre de non uniformité de plaque à plaque inférieur à 1% sur 10 plaques. Ce paramètre est l'écart-type des vitesses d'enlèvement pour une série de valeurs obtenues dans des conditions de procédé équivalentes, divisé par la valeur moyenne de la vitesse d'enlèvement sur cette même série, et multiplié par 100. Dans l'hypothèse selon laquelle la vitesse d' enlèvement du dioxyde de silicium suit la loi de Preston, la sélectivité obtenue avec la composition selon l'invention est croissante lorsque la vitesse de rotation du plateau de la polisseuse et/ou la pression appliquée au substrat à polir sont décroissantes, pour des valeurs très faibles de la vitesse de rotation et/ou de la pression. The excellent reproducibility of the method employing the composition described above is also confirmed by a plate-to-plate non-uniformity parameter of less than 1% on 10 plates. This parameter is the standard deviation of the removal rates for a series of values obtained under equivalent process conditions, divided by the average value of the removal rate on that same series, and multiplied by 100. In the hypothesis according to which the rate of removal of silicon dioxide follows the Preston law, the selectivity obtained with the composition according to the invention is increasing when the rotational speed of the polisher plate and / or the pressure applied to the substrate to be polished are decreasing, for very low values of the speed of rotation and / or the pressure.

Claims

Revendications claims
1. Composition de polissage mécano chimique comprenant un mélange de silice, de nitrate ferrique, d'acide nitrique et d'eau, caractérisée en ce que la silice est une silice pyrogénée dont la taille moyenne de particule agrégée en suspension est comprise entre 50 nm et 200 nm, de préférence entre 120 nm et 160 nm.1. A chemical mechanical polishing composition comprising a mixture of silica, ferric nitrate, nitric acid and water, characterized in that the silica is a fumed silica whose mean aggregate particle size in suspension is between 50 nm and 200 nm, preferably between 120 nm and 160 nm.
2. Composition selon la revendication 1, caractérisée en ce qu'elle comprend entre 5% et 15% en poids de silice pyrogénée, entre 0,5% et 3% en poids de nitrate ferrique et entre 0,1% et 0,5% en poids d'acide nitrique.2. Composition according to claim 1, characterized in that it comprises between 5% and 15% by weight of fumed silica, between 0.5% and 3% by weight of ferric nitrate and between 0.1% and 0.5% by weight. % by weight of nitric acid.
3. Composition selon la revendication 2, caractérisée en ce qu'elle comprend 10% en poids de silice pyrogénée, 1,67% en poids de nitrate ferrique et entre 0,2% et 0,5% en poids d'acide nitrique.3. Composition according to claim 2, characterized in that it comprises 10% by weight of fumed silica, 1.67% by weight of ferric nitrate and between 0.2% and 0.5% by weight of nitric acid.
4. Composition selon l'une quelconque des revendications 1 à 3, caractérisée en ce que la silice pyrogénée est une poudre dont les agrégats possèdent une surface spécifique BET comprise entre 90 m2/g et 300 m2/g, et de préférence de l'ordre de 130 m2/g.4. Composition according to any one of claims 1 to 3, characterized in that the fumed silica is a powder whose aggregates have a BET specific surface area of between 90 m 2 / g and 300 m 2 / g, and preferably of the order of 130 m 2 / g.
5. Composition selon l'une quelconque des revendications 1 à 4, caractérisée en ce que l'acide nitrique est présent dans une quantité permettant d'ajuster le pH de ladite composition entre 1,2 et 2, de préférence à 1,35.5. Composition according to any one of claims 1 to 4, characterized in that the nitric acid is present in an amount for adjusting the pH of said composition between 1.2 and 2, preferably 1.35.
6. Composition selon l'une quelconque des revendications 1 à 5, caractérisée en ce que le nitrate ferrique est le nitrate ferrique nonahydrate et/ou en ce que l'eau est de l'eau déionisée. 6. Composition according to any one of claims 1 to 5, characterized in that the ferric nitrate is ferric nitrate nonahydrate and / or in that the water is deionized water.
7. Procédé de préparation de la composition selon l'une quelconque des revendications 1 à 6, caractérisé en ce qu' il comprend les étapes suivantes : a) Dans un premier temps, dispersion de la silice pyrogénée dans une solution d' acide nitrique pour obtenir une concentration en silice comprise entre 15% et 30% en poids ; b)Dans un deuxième temps, addition d'une solution de nitrate ferrique à la dispersion obtenue à l'étape précédente afin d' obtenir une concentration en silice comprise entre 5% et 15% en poids.7. Process for the preparation of the composition according to any one of claims 1 to 6, characterized in that it comprises the following steps: a) In a first step, dispersion of the fumed silica in a solution of nitric acid for obtain a silica concentration of between 15% and 30% by weight; b) In a second step, addition of a ferric nitrate solution to the dispersion obtained in the preceding step in order to obtain a silica concentration of between 5% and 15% by weight.
8. Utilisation de la composition selon l'une quelconque des revendications 1 à 6 pour le polissage mécano chimique de couches appliquées sur un substrat portant au moins un micro composant semi-conducteur.8. Use of the composition according to any one of claims 1 to 6 for the chemical mechanical polishing of layers applied to a substrate carrying at least one micro component semiconductor.
9. Utilisation selon la revendication 8, caractérisée en ce que ledit substrat est recouvert d'une couche (6) métallique, ladite couche métallique comprenant par exemple du tungstène.9. Use according to claim 8, characterized in that said substrate is covered with a layer (6) metal, said metal layer comprising for example tungsten.
10. Utilisation selon la revendication 8 ou 9, caractérisée en ce que ledit substrat est recouvert d'une couche (2) de matériau isolant, ledit matériau isolant comprenant par exemple de l'oxyde de silicium.10. Use according to claim 8 or 9, characterized in that said substrate is covered with a layer (2) of insulating material, said insulating material comprising for example silicon oxide.
11. Utilisation selon l'une quelconque des revendications 8 à 10, caractérisée en ce que ledit substrat est recouvert d'au moins une couche (4,5) d'adhérence, ladite couche comprenant par exemple du titane et/ou du nitrure de titane. 11. Use according to any one of claims 8 to 10, characterized in that said substrate is covered with at least one layer (4,5) of adhesion, said layer comprising for example titanium and / or nitride of titanium.
PCT/FR2005/001641 2004-07-08 2005-06-28 Mechanochemical polishing composition, preparing and using method WO2006016030A1 (en)

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EP0708160A2 (en) * 1994-10-06 1996-04-24 Cabot Corporation Chemical mechanical polishing slurry for metal layers
US6136711A (en) * 1997-07-28 2000-10-24 Cabot Corporation Polishing composition including an inhibitor of tungsten etching
US6294105B1 (en) * 1997-12-23 2001-09-25 International Business Machines Corporation Chemical mechanical polishing slurry and method for polishing metal/oxide layers
US6582623B1 (en) * 1999-07-07 2003-06-24 Cabot Microelectronics Corporation CMP composition containing silane modified abrasive particles

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EP0708160A2 (en) * 1994-10-06 1996-04-24 Cabot Corporation Chemical mechanical polishing slurry for metal layers
US6136711A (en) * 1997-07-28 2000-10-24 Cabot Corporation Polishing composition including an inhibitor of tungsten etching
US6294105B1 (en) * 1997-12-23 2001-09-25 International Business Machines Corporation Chemical mechanical polishing slurry and method for polishing metal/oxide layers
US6582623B1 (en) * 1999-07-07 2003-06-24 Cabot Microelectronics Corporation CMP composition containing silane modified abrasive particles

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100224103A1 (en) * 2007-09-14 2010-09-09 De Frazer International Sdn Bhd Paper pallets

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