DE102006031339A1 - Solid electrolyte memory structure, useful in conductive bridging random access memory, dynamic random access memory and programmable metallization cell, comprises a solid electrolyte layer, a metal layer, and a corrosion resistance layer - Google Patents

Abstract

Solid electrolyte memory structure (A) comprises a solid electrolyte layer, a metal layer on the solid electrolyte layer, and a corrosion resistance layer (110) on the metal layer. An independent claim is included for the preparation of (A) comprising sequentially forming the solid electrolyte layer, metal layer, corrosion resistance layer and a hard mask layer (whose corrosion is prevented by the corrosion resistance layer).

Description

The The invention relates to a memory structure and in particular solid electrolyte memory structures and methods of making the same.

Of the Structuring Process of Conductive Bridging Multiple Access Memory Elements (Conductive bridging random access memory, CBRAM), which also as Phase metallization cells elements (Phase Metallization Cell, PMC) is a key process step as part of the process of establishing a functioning CBRAM facility.

In the integration scheme becomes common a metallic hardmask provided which is in direct contact stands with the Conductive Bridging stack, which contains a chalcogenide layer, wherein the chalcogenide layer, for example germanium selenide (GeSe) or germanium sulphide (GeS), and on the chalcogenide layer a silver layer, without one Layer between the metal hardmask and the conductive bridging stack is provided.

Usually For example, the metal hard mask layer is patterned using of halogen plasma chlorine or halogen plasma fluorine. A problem with structuring Using halogen plasma can be seen in that in this process silver (Ag) forms quite large deposits, when the silver is exposed to the halogen plasma. The making of the Agglomeration makes the etching step in the context of making the Conductive Bridging stack very difficult.

Of the Invention is based on the object, a Conductive Bridging stack in a more reliable way manufacture.

The Problem is caused by a memory structure as well as by a method for producing a memory structure having the features according to the independent patent claims.

A Solid electrolyte memory structure has on a solid electrolyte layer, a metal layer on the solid electrolyte layer and an etch stop layer on the metal layer.

exemplary Embodiments of the invention will become apparent from the dependent claims.

In an embodiment The invention features the solid electrolyte storage structure a hardmask layer, For example, a metal hardmask layer disposed on the etch stop layer is arranged. The metal hard mask layer can be made of titanium (Ti), titanium nitride (TiN), tantalum (Ta) or tantalum nitride (TaN) or a combination of these Materials.

In another embodiment The invention is the solid electrolyte layer made of chalcogenide material, the chalcogenide material May contain metal ions. The metal ions may be selected from a group of silver (Ag), copper (Cu), zinc (Zn) or a combination or an alloy of these materials.

Further may be the chalcogenide material according to one embodiment selected the invention be made of a group of materials consisting of sulfur (S), Selenium (Se), germanium (Ge), tellurium (Te), tungsten (W) or one Combination or an alloy of these materials.

The chalcogenide material may be formed, for example, germanium selenide (GeSe), germanium sulfide (GeS), tungsten oxide (WO _x ).

Further For example, the metal layer may be formed of a silver-containing material become.

According to one another embodiment of the Invention may be the etch stop layer be made or consist of a material that has a high etching resistance across from hard mask etching chemistry Has. In other words, the etch stop layer be made or consist of a material that has an etching resistance which is larger as a predetermined threshold, over the etchant used becomes an etching the hard mask.

Further may be the etch stop layer selected in this way be that it also acts as a diffusion barrier for the metal layer, in other words, for that Material, which for the metal layer is used.

For example For example, the etch stop layer may be prepared are made of a material that is selected from a group of Materials consisting of ruthenium (Ru), cobalt (Co), nickel (Ni), nickel-iron (NiFe), nickel-iron-chromium (NiFeCr), platinum (Pt), platinum-manganese (PtMn), iridium (Ir), iridium-manganese (IrMn) or a combination or an alloy of these materials. Any other suitable Material can for the etch stop layer used if it has a sufficiently high etching resistance across from the hardmask etch chemistry used having.

It should be noted that these materials are particularly suitable as an etch stop layer in the case where a metal layer of a silver-containing chalcogenide is used. However, it is Note that any other suitable material may be used for the etch stop layer between the conductive bridging stack containing the chalcogenide material, in other words, the ion conducting material, and the silver layer, on the one hand, and the hardmask material , on the other hand.

• – das Ätzstopp-Schicht-Material sollte leitfähig sein;
• – das Ätzstopp-Schicht-Material sollte eine hohe Ätz-Selektivität bezüglich des Hartmasken-Materials während des Hartmasken-Öffnungs-Ätz-Prozesses aufweisen, so dass es ermöglicht wird, eine sehr dünne Schicht als Ätzstopp-Schicht zu verwenden in der Größenordnung von einigen wenigen Nanometern, beispielsweise in einem Bereich einer Dicke von 2 nm bis 20 nm, beispielsweise in einem Bereich einer Dicke von 2 nm bis 10 nm, beispielsweise in einem Bereich einer Dicke von 2 nm bis 5 nm;
• – das Ätzstopp-Schicht-Material sollte eine gute Haftung zu den Materialien des Conductive Bridging-Stapels aufweisen, insbesondere mit dem Silber-Material, das für die oberste Schicht dieses Conductive Bridging-Stapels verwendet wird, und zu dem Hartmasken-Material, beispielsweise Titan-Nitrid (TiN) oder Tantal-Nitrid (TaN);
• – das Ätzstopp-Schicht-Material sollte ferner geeignet sein, um als Diffusionsbarriere für das Material auf der obersten Schicht des Conductive Bridging-Stapels zu dienen, beispielsweise Silber, sowie für Halogen-Spezies;
• – das Ätzstopp-Schicht-Material sollte eine vergleichbare oder höhere Ätzrate während des Ätzens des Conductive Bridging-Stapels aufweisen während des Prozesses, der dem Strukturieren der Hartmaske folgt;
• – das Ätzstopp-Schicht-Material sollte einen allenfalls vernachlässigbaren negativen Effekt oder sogar vorteilhafte Effekte auf die Eigenschaften der Conductive Bridging-Verbindung haben.

Some advantageous properties for this material that should be at least partially met are:

• The etch stop layer material should be conductive;
• The etch stop layer material should have a high etch selectivity with respect to the hard mask material during the hard mask opening etch process so that it is possible to use a very thin layer as an etch stop layer on the order of a few a few nanometers, for example in a range of thickness of 2 nm to 20 nm, for example in a range of thickness of 2 nm to 10 nm, for example in a range of thickness of 2 nm to 5 nm;
• The etch stop layer material should have good adhesion to the materials of the conductive bridging stack, in particular to the silver material used for the top layer of this conductive bridging stack and to the hard mask material, for example titanium Nitride (TiN) or tantalum nitride (TaN);
• The etch stop layer material should also be able to serve as a diffusion barrier for the material on the uppermost layer of the conductive bridging stack, for example silver, as well as for halogen species;
• The etch stop layer material should have a comparable or higher etch rate during the etching of the conductive bridging stack during the process following the patterning of the hard mask;
• The etch stop layer material should have negligible negative effect or even beneficial effects on the properties of the conductive bridging compound.

The above-mentioned materials Ru, NiFe, NiFeCr, Pt, PtMn, Ir, IrMn, or the like fulfill the above requirements for TiN or TaN as a hard mask material and Ag as the top layer of the Conductive bridging stacks.

As in the following even closer explained will allow the etch stop layer, which is provided on the uppermost layer of the Conductive Bridging stack and the hardmask layer disposed on the etch stop layer is, a reliable etch stop, when the hardmask layer material is patterned on the etch stop layer by preventing the formation of silver halide.

In In other words, according to one embodiment The invention additionally provides an etch stop layer on the Conductive Bridging stack, increasing the etch window and whereby a physical contact between the etchant, generally the chemistry used to open the hardmask and the Conductive Bridging stack material, for example with Ag.

In another embodiment The invention provides a memory structure which is ion conducting Contains material, a metal layer on the ion conductive material and an etch stop layer on the metal layer, as well as a hardmask layer on the etch stop layer.

The Hard mask layer may be a metal hard mask layer and it can be made of titanium (Ti), titanium nitride (TiN), tantalum (Ta), or tantalum nitride (TaN).

According to another embodiment of the invention, the ion-conductive material is made of a chalcogenide material, wherein the ionically conductive material can be made of or may consist of GeS, GeSe, WO _X.

Further For example, the metal layer may be formed of a silver-containing material be.

In another embodiment The invention may provide the etch stop layer be made of a material which is selected from a group of materials consisting of Ru, NiFe, NiFeCr, Pt, PtMn, Ir, IrMn, or a combination or alloy of these materials.

According to one another embodiment of the The invention will be a solid electrolyte storage structure provided a solid electrolyte layer made of a chalcogenide material, a silver layer on the solid electrolyte layer, an etch stop layer on the metal layer, wherein the etch stop layer is made of a material is made, which is selected is a group of materials consisting of Ru, NiFe, NiFeCr, Pt, PtMn, Ir, IrMn, and a metal hardmask layer on the etch stop layer.

Further the metal hard mask layer may be made of titanium (Ti), Titanium nitride (TiN), tantalum (Ta), or tantalum nitride (TaN).

• – Bilden einer Festkörperelektrolyt-Schicht;
• – Bilden einer Metall-Schicht auf der Festkörperelektrolyt-Schicht;
• – Bilden einer Ätzstopp-Schicht auf der Metall-Schicht;
• – Bilden einer Hartmasken-Schicht auf der Ätzstopp-Schicht;
• – Ätzen der Hartmasken-Schicht;
• – Stoppen des Ätzens unter Verwendung der Ätzstopp-Schicht als Ätz-Stopp.

According to another aspect of the invention, there is provided a method of manufacturing a solid electrolyte memory structure, comprising:

• Forming a solid electrolyte layer;
• - Forming a metal layer on the solids lektrolyt layer;
• Forming an etch stop layer on the metal layer;
• Forming a hardmask layer on the etch stop layer;
• - etching the hardmask layer;
• Stop etching using the etch stop layer as an etch stop.

In An embodiment of the method comprises forming the hardmask layer forming a metal hardmask layer.

Further In the method, forming the metal hard mask layer may include forming the metal hard mask layer using a material which is selected from a group of materials consisting of titanium (Ti), titanium nitride (TiN), tantalum (Ta), or tantalum nitride (TaN).

In Another embodiment of the invention comprises forming the solid electrolyte layer on the formation of chalcogenide material, for example using a material that is selected is made up of a group of materials consisting of sulfur (S), Selenium (Se), germanium (Ge), tellurium (Te), tungsten (W) or a combination or an alloy of these materials.

Further may include forming the metal layer on the solid electrolyte layer forming the metal layer using a silver-containing material.

Further For example, forming the etch stop layer may occur the metal layer comprise forming the etch stop layer using a material selected from a group of Materials consisting of Ru, Co, Ni, NiFe, NiFeCr, Pt, PtMn, Ir, IrMn, or a combination or alloy of these materials.

embodiments The invention are illustrated in the figures and will be explained in more detail below.

It demonstrate

1 a solid electrolyte memory cell according to a first embodiment of the invention;

2a to 2k a manufacturing method of a solid electrolyte memory cell array according to a second embodiment of the invention.

in the The scope of this description will be the same or similar Elements, where appropriate, identical reference numerals used.

1 shows a Conductive Bridging memory cells 100 according to a first embodiment of the invention.

On a substrate 102 , for example, silicon, is a lower electrode 104 For example, from tungsten or tungsten silicide provided. Further, on the lower electrode 104 ion-conducting material 106 , for example, chalcogenide as described above, followed by deposition from a silver layer 108 which provides the metal ions which enter the ion conducting material 106 be introduced in a subsequent step, for example by means of photodiffusion or by annealing the silver layer 108 ,

According to one embodiment of the invention, an etch stop layer 110 of Ru, Co, Ni, NiFe, NiFeCr, Pt, PtMn, Ir, IrMn or the like provided on the silver layer 108 wherein the etch stop layer 110 has a thickness of a few nanometers, for example 2 nm to 20 nm, for example 2 nm to 10 nm, for example 2 nm to 5 nm.

Further, a metal hard mask layer 112 provided, for example, TiN or TaN on the Ätzstopp layer 110 ,

How about the 2a to 2k will be explained in more detail, the metal hard mask layer 112 patterned using hardmask open-etch chemistry, wherein the plasma etch process used thereby is stopped on the etch stop layer 110 , bringing the silver layer 108 is protected and the formation of silver buildup is prevented.

2a to 2k show the method for manufacturing a solid electrolyte memory cell array comprising a plurality of memory cells, wherein, for the sake of clarity, only two memory cells are shown. However, any number of hundreds and thousands or millions of memory cells may be provided in the solid electrolyte memory cell array, the memory cells being arranged in an array, for example in a matrix in rows and columns.

It It should be noted that for reasons the simplicity described only the memory cell units and are shown in the figures. The so-called front-end-of-line (FEOL) modules, which transistors, Word lines and bit lines are not in the figures shown.

In an embodiment of the invention The described CBRAM memory cells are connected to the source / drain regions of the respective transistors by means of vias, which are electrically connected to the lower electrode 214 are coupled, as will be explained in more detail below. This connection scheme is similar to that used in dynamic random access memory (DRAM) to connect the capacitors. Thus, the vias are quenchers in an electrically insulating dielectric layer, such as low-K material, silicon oxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), or the like.

As in a first structure 200 in 2a is shown, a layer 202 of dielectric material, under which there are one or more FEOL modules, which are not shown in the figures.

In a subsequent step, as in a second structure 204 in 2 B 2, according to a conventional damascene process, the substrate 202 structured, with which trenches in the structured substrate 206 are formed, wherein, as will be described in more detail below, lower electrodes of the conductive bridging memory cells are formed.

As in a third structure 208 in 2c Trenches are filled and possibly overfilled with a metal, according to an embodiment of the invention with tungsten (W), tungsten silicide (WSi), or copper (Cu). In an alternative embodiment of the invention, the trenches are filled or optionally overfilled with doped polysilicon by means of a metal deposition process, for example by means of a chemical vapor deposition (CVD) or a physical vapor deposition (PVD) process ) or by electrochemical deposition.

Further, the excess material of the metal or polysilicon is removed by a chemical mechanical polishing (CMP) process such that the CMP is stopped on the upper surface of the patterned substrate 206 , bringing the lower electrodes 214 electrically isolated from each other (hereinafter also referred to as first electrodes 214 ) (see fourth structure 212 in 2d ).

After the lower electrodes 214 were formed chalcogenide material (ion-conductive material, in other words), for example GeSe, GeS, WO _x, or the like, provided on the upper surface of the patterned substrate 206 and the exposed lower surfaces of the first electrodes 214 , whereby a chalcogenide layer 218 is formed (see fifth structure 216 in 2e ).

Subsequently, a silver layer 222 on the chalcogenide layer 218 deposited, as in a sixth structure 220 in 2f is shown.

Then, an etching stop layer 226 as described above on the silver layer 222 deposited, wherein the etch stop layer 226 is deposited with a layer thickness of a few nanometers, for example with a layer thickness of 2 nm to 5 nm (see seventh structure 224 in 2g ).

As in 2h is shown, according to an embodiment of the invention, a metal hard mask layer 230 TiN or TaN on the etch stop layer 226 deposited (see eighth structure 228 ).

Then the metal hard mask layer becomes 230 structured to prepare the etching of the conductive bridging stacks, thus providing a patterned hardmask layer 234 is formed, as in the ninth structure 332 in 2i is shown.

The hard mask layer 230 is patterned in a manner such that the remaining portions of the patterned hardmask layer 234 over the first electrodes 214 are arranged to protect them during the subsequent etching process for etching the conductive bridging memory cells. The first electrodes 214 and the remaining portions of the patterned hardmask layer 234 overlap each other at least partially in the lateral direction.

As in 2y (see tenth structure 236 ), a further etching process is performed, whereby the etch stop layer 226 and the silver layer 222 and the chalcogenide layer 218 is etched, wherein the etching process is stopped on the upper surface of the patterned substrate 206 ,

As in the eleventh structure 214 in 2k is shown, the structured cells, which are the layers 218 . 222 . 226 . 234 contained, encapsulated by means of an electrically insulating layer 244 , such as silicon oxide (SiO ₂ ) or silicon nitride (Si ₃ N ₄ ).

In the case of the trenches 242 with the insulating material 244 are overfilled, the excess and supernatant material is removed by a CMP process (not shown in the figures). The textured hard mask layer 234 is connected to an upper metal trace (not shown in the figures).

To the to complete of the CBRAM array become conventional Process steps provided and performed to form the word line elements and bit line elements and their respective contacting portions and, if desired, the respective Passivierungsschritte (also not in the figures shown).

In an alternative embodiment of the invention, a common upper electrode is provided, which is arranged on the cell block, instead of structured individual cells, as used in the exemplary embodiment according to FIGS 2a to 2k are described.

100

Conductive Bridging memory cell

102

substratum

104

lower electrode

106

ion-conducting material

108

Silver layer

110

Etch-stop layer

112

Metal hardmask

200

first structure

202

layer made of dielectric material

204

second structure

206

structured substratum

208

third structure

210

metal

212

fourth structure

214

lower electrode

216

fifth structure

218

Chalcogenide layer

220

sixth structure

222

Silver layer

224

seventh structure

226

Etch-stop layer

228

eighth structure

230

Metal hard mask layer

232

ninth structure

234

structured Hard mask layer

236

tenth structure

240

eleventh structure

242

structured cell

244

insulating layer

Claims (20)

Solid electrolyte memory structure comprising: - one Solid electrolyte layer; - a metal layer on the solid electrolyte layer; and An etch stop layer on the metal layer. Solid electrolyte storage structure according to claim 1, further comprising a hardmask layer on the etch stop layer. Solid electrolyte storage structure according to claim 2, wherein the hard mask layer is a metal hard mask layer. Solid electrolyte storage structure according to claim 2 or 3, wherein the metal hardmask layer is made of Titanium, titanium nitride, tantalum, tantalum nitride or a combination of these materials. Solid electrolyte storage structure according to one the claims 1 to 4, wherein the solid electrolyte layer is made of a chalcogenide material. Solid electrolyte storage cell according to claim 5, wherein the chalcogenide material contains metal ions. Solid electrolyte storage structure according to claim 6, with the metal ions selected are made of a group of materials consisting of silver, copper, Zinc or a combination or alloy of these materials. Solid electrolyte storage structure according to claim 6 or 7, wherein the chalcogenide material is selected from a group of Materials consisting of sulfur, selenium, germanium, tellurium, tungsten or a combination or alloy of these materials. A solid state electrolyte memory cell according to any one of claims 5 to 8, wherein the chalcogenide material is GeS, GeSe or WO _X. Solid electrolyte storage structure according to one the claims 1 to 9, wherein the metal layer is made of a silver-containing Material. Solid electrolyte storage structure according to one the claims 2-10, wherein the etch stop layer made of a material having a high etching resistance in terms of the hardmask etch chemistry used having. Solid electrolyte storage structure according to one the claims 1 to 11, wherein the etch stop layer additionally as a diffusion barrier for the metal layer is formed. Solid electrolyte storage structure according to one the claims 1 to 12, wherein the etch stop layer is made of a material which is selected from a group of materials consisting of Ru, NiFe, NiFeCr, Pt, PtMn, Ir, IrMn or a combination or alloy these materials. Method for producing a solid electrolyte storage structure, - in which a solid electrolyte layer is formed; - at which forms a metal layer on the solid electrolyte layer becomes; - at an etch stop layer is formed on the metal layer; - In which a hard mask layer formed on the etch stop layer becomes; - at etched the hardmask layer becomes; - at the etching is stopped using the etch stop layer as an etch stop. Method according to claim 14, in which a metal hardmask layer is formed as a hardmask layer becomes. Method according to claim 15, wherein as a metal hard mask layer, a metal hard mask layer is formed using material which is selected from a group of materials consisting of titanium, titanium nitride, Tantalum, Tantalum Nitride. Method according to one the claims 14 to 16, wherein a chalcogenide material layer as a solid electrolyte layer is formed. Method according to claim 25 in which chalcogenide material is formed using a material that is selected is made of a group of materials consisting of sulfur, selenium, Germanium, tellurium, tungsten or a combination or alloy of these materials. Method according to one the claims 14 to 18, in which the metal layer on the solid electrolyte layer using is formed of silver-containing material. Method according to one the claims 14 to 19, wherein as etch stop layer a layer on the metal layer is formed from a material which is selected from a group of materials consisting of Ru, NiFe, NiFeCr, Pt, PtMn, Ir, IrMn or a combination or alloy thereof Materials.