US20090108315A1 - Trench memory with monolithic conducting material and methods for forming same - Google Patents
Trench memory with monolithic conducting material and methods for forming same Download PDFInfo
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- US20090108315A1 US20090108315A1 US12/348,939 US34893909A US2009108315A1 US 20090108315 A1 US20090108315 A1 US 20090108315A1 US 34893909 A US34893909 A US 34893909A US 2009108315 A1 US2009108315 A1 US 2009108315A1
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- 238000000034 method Methods 0.000 title abstract description 26
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims abstract description 7
- 229920005591 polysilicon Polymers 0.000 claims abstract description 7
- 239000003990 capacitor Substances 0.000 claims description 12
- 229910000577 Silicon-germanium Inorganic materials 0.000 claims description 3
- LEVVHYCKPQWKOP-UHFFFAOYSA-N [Si].[Ge] Chemical compound [Si].[Ge] LEVVHYCKPQWKOP-UHFFFAOYSA-N 0.000 claims description 3
- 229910045601 alloy Inorganic materials 0.000 claims description 3
- 239000000956 alloy Substances 0.000 claims description 3
- 229910052751 metal Inorganic materials 0.000 claims description 3
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- 239000000463 material Substances 0.000 description 22
- 239000003989 dielectric material Substances 0.000 description 18
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 16
- 229910052581 Si3N4 Inorganic materials 0.000 description 9
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 9
- 239000004065 semiconductor Substances 0.000 description 8
- 239000000758 substrate Substances 0.000 description 7
- 229910052814 silicon oxide Inorganic materials 0.000 description 6
- 235000012239 silicon dioxide Nutrition 0.000 description 5
- 239000000377 silicon dioxide Substances 0.000 description 5
- 239000011521 glass Substances 0.000 description 3
- 238000004544 sputter deposition Methods 0.000 description 3
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 2
- NRTOMJZYCJJWKI-UHFFFAOYSA-N Titanium nitride Chemical compound [Ti]#N NRTOMJZYCJJWKI-UHFFFAOYSA-N 0.000 description 2
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- 238000005240 physical vapour deposition Methods 0.000 description 2
- 239000002861 polymer material Substances 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
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- 230000002123 temporal effect Effects 0.000 description 2
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- 229910052719 titanium Inorganic materials 0.000 description 2
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 2
- 229910052721 tungsten Inorganic materials 0.000 description 2
- 239000010937 tungsten Substances 0.000 description 2
- WQJQOUPTWCFRMM-UHFFFAOYSA-N tungsten disilicide Chemical compound [Si]#[W]#[Si] WQJQOUPTWCFRMM-UHFFFAOYSA-N 0.000 description 2
- 229910021342 tungsten silicide Inorganic materials 0.000 description 2
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Images
Classifications
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B12/00—Dynamic random access memory [DRAM] devices
- H10B12/30—DRAM devices comprising one-transistor - one-capacitor [1T-1C] memory cells
- H10B12/37—DRAM devices comprising one-transistor - one-capacitor [1T-1C] memory cells the capacitor being at least partially in a trench in the substrate
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B12/00—Dynamic random access memory [DRAM] devices
- H10B12/01—Manufacture or treatment
- H10B12/02—Manufacture or treatment for one transistor one-capacitor [1T-1C] memory cells
- H10B12/03—Making the capacitor or connections thereto
- H10B12/038—Making the capacitor or connections thereto the capacitor being in a trench in the substrate
- H10B12/0385—Making a connection between the transistor and the capacitor, e.g. buried strap
Definitions
- the present invention relates generally to manufacturing of a semiconductor device. More specifically, the present invention provides a method and apparatus for forming a trench memory, such as dynamic random access memory (DRAM), with a monolithic conducting material.
- DRAM dynamic random access memory
- a trench memory for example a dynamic random access memory (DRAM) is depicted, in cross-sectional view, in FIG. 1 .
- the trench memory (e.g., DRAM) 1 has one capacitor 2 and one transistor 4 and further includes various constructs located within, or upon, a semiconductor substrate 6 .
- Trench memory 1 includes capacitor 2 , typically located within a trench 8 , that is connected to a transistor (e.g., conventional MOSFET) 4 via a buried strap 10 .
- Transistor 4 includes a gate conductor 12 , gate dielectric 14 , and a drain 16 and a source 18 on either side of gate conductor 12 .
- a node dielectric 20 Lining a portion of trench 8 is a node dielectric 20 . Above node dielectric 20 , also lining a portion of trench 8 is an insulating collar 22 (or collar oxide). Also within trench 8 is conducting materials 24 A, 24 B, and 24 C which conventionally are doped polysilicon (hereinafter “poly”). Located upon insulating collar 22 is a shallow trench isolation (STI) 26 .
- STI shallow trench isolation
- trench 8 is filled by three (3) polysilicon materials (i.e., first poly 24 A, second poly 24 B, and third poly 24 C). Because three poly materials 24 A, 24 B, 24 C are placed within trench 8 at temporally distinct times, poly materials 24 A, 24 B, 24 C are not monolithic. That is conducting materials 24 A, 24 B, 24 C are not one, integrated piece of conducting material 24 in trench 8 .
- First poly 24 A is placed first.
- Second poly 24 B is placed later, after placement of first poly 24 A and intermittent steps.
- Third poly 24 C is placed later, after placement of second poly 24 B and other intermittent steps, as well.
- Interfaces are created where each poly 24 abuts another adjoining poly 24 .
- a poly 24 to poly 24 interface is created where first poly 24 A meets second poly 24 B.
- a second poly 24 to poly 24 interface is created where second poly 24 B and third poly 24 C meet.
- each interface increases the overall resistance of trench 8 , thereby causing a concomitant reduction in the overall performance of trench memory 1 .
- a trench memory filled with a monolithic conducting material and methods for forming the same are disclosed.
- the trench memory includes a trench that has only a single, monolithic conducting material within the trench.
- the method includes forming a trench with a collar in the trench; forming a node dielectric on a sidewall of the trench; and filling the trench with a monolithic conducting material, such as polysilicon.
- a first aspect of the present invention provides a method of forming a trench memory, comprising the steps of: forming a trench with a collar in the trench; forming a node dielectric on a sidewall of the trench; and filling the trench with a monolithic conducting material.
- a second aspect of the present invention provides a trench memory comprising: a capacitor in a trench; a collar disposed above the capacitor; and an access transistor connected to the capacitor through a buried strap, wherein the trench is filled with a monolithic conducting material.
- a third aspect of the present invention provides a method of forming a trench memory comprising: forming a collar in an upper portion of a trench; forming a capacitor in a lower portion of the trench below the collar; and connecting a transistor to the capacitor, through a buried strap, wherein the trench is filled with a monolithic conducting material
- FIG. 1 depicts a cross-sectional elevation view of a multiple poly fill trench memory in the related art.
- FIGS. 2A-2E depict cross-section elevation views of steps of forming a trench memory with monolithic conducting material, in accordance with a first embodiment of the present invention.
- FIG. 3 depicts a cross-sectional elevation view of a first embodiment of a completed trench memory with monolithic conducting material, in accordance with the present invention.
- FIGS. 4A-4G depict cross-section elevation views of steps of forming a trench memory with monolithic conducting material, in accordance with a second embodiment of the present invention.
- FIG. 5 depicts a cross-sectional elevation view of a second embodiment of a completed trench memory with monolithic conducting material, in accordance with the present invention.
- the present invention provides a trench memory with monolithic conducting material and methods of forming the trench memory with monolithic conducting material.
- FIGS. 2A through 2E depict cross-section elevation views of a trench memory 30 undergoing the various steps of constructing a trench memory with monolithic conducting material in accordance with a first embodiment of the present invention.
- FIG. 3 depicts the finished first embodiment (i.e., completed trench memory 30 ).
- FIGS. 4A through 4G depict cross-section elevation views of various steps of forming of trench memory 130 with a monolithic conductive material in accordance with a second embodiment of the present invention.
- FIG. 5 depicts a finished second embodiment (i.e., completed trench memory 130 ).
- FIG. 2A shows the starting of a process to form trench memory 30 in a first embodiment of the present invention wherein trench memory 30 has a pad layer 32 (e.g., silicon nitride) above a semiconductor (e.g., silicon) substrate 34 . Between pad layer 32 and semiconductor substrate 34 may be an underlying silicon dioxide (SiO 2 ) layer (not shown). Formed into semiconductor substrate 34 is a trench 36 . Further formed in the upper portion of trench 36 is an insulating collar 38 typically made of silicon dioxide (SiO 2 ), silicon nitride (Si 3 N 4 ), or any suitable dielectric material. Methods for forming an insulating collar 38 in upper trench 36 are well known in the art and therefore are not described in detail in order to avoid obscuring the invention.
- insulating collar 38 typically made of silicon dioxide (SiO 2 ), silicon nitride (Si 3 N 4 ), or any suitable dielectric material.
- FIG. 2B follows wherein a node dielectric material 40 is formed, or deposited, on sidewall of trench 36 .
- Node dielectric material 40 may be silicon nitride (Si 3 N 4 ), silicon dioxide (SiO 2 ), or other suitable dielectric material formed by thermal growth, sputtering, deposition, or other suitable techniques.
- a filling material 42 is placed within trench 36 so as to abut node dielectric material 40 .
- Filling material 42 may be spin on glass (SOG), resist, or other suitable material.
- Filling material 42 is recessed, or removed, partially from trench 36 to a point along insulating collar 38 by any conventional recess process such as reactive ion etch (RIE), chemical downstream etch (CDE), or other suitable etch techniques now known or later developed.
- RIE reactive ion etch
- CDE chemical downstream etch
- FIG. 2C portions of node dielectric material 40 and insulating collar 38 (i.e., portion above filling material 42 ) are removed from trench 36 .
- insulating collar 38 , dielectric material 40 , and filling material 42 that remain within trench 36 are substantially at the same height in trench 36 .
- filling material 42 ( FIG. 2C ) is removed in its entirety from trench 36 , such that insulating collar 38 and dielectric material 40 remains in trench 36 as shown in FIG. 2D .
- Removal techniques may include RIE, CDE, wet etch and other suitable removal techniques now known or later developed.
- FIG. 2E follows wherein a conducting material 52 is placed in trench 36 .
- Placement techniques may include chemical vapor deposition (CVD), atomic layer deposition (ALD), physical vapor deposition (PVD), sputtering, plating, and other suitable techniques now known or later developed.
- Conducting material 52 may be placed so as to substantially, or completely, fill trench 36 .
- conducting material 52 is placed in trench 36 to an amount so as to abut, or adjoin, adjacent buried strap 46 ( FIG. 3 ), so as to create connectivity between conducting material 52 and buried strap 46 .
- conducting material 52 may be doped polysilicon, although other suitable conducting material such as a doped silicon germanium, a metal (e.g., tungsten, titanium, etc.) or an alloy (e.g., tungsten silicide, titanium nitride, etc.). Placement may be done in a monolithic fashion so that single conducting material 52 is a single piece; so that there exists no interfaces in conducting material 52 . Further, conducting material 52 may be placed in one temporal step, rather than three steps (or, in multiple steps), thereby reducing process time and cost.
- STI shallow trench isolation
- FIG. 3 depicts a first embodiment of a finished trench memory 30 (e.g., DRAM) wherein an upper portion of single conducting material 52 has been partially recessed and thereupon STI 44 has been formed.
- completed trench memory 30 includes a buried strap 46 that is contiguous with monolithic conducting material 52 .
- trench memory 30 has a lower, and thereby improved, resistance because there are no interfaces within conducting material 52 .
- Completed trench memory (e.g., DRAM) 30 includes one capacitor 49 and one transistor (e.g., conventional MOSFET) 48 connected via a buried strap 46 to each other.
- Transistor 48 includes a gate conductor 50 , gate dielectric 52 , and a drain 54 and a source 56 on either side of gate conductor 50 .
- FIG. 4A shows the starting of a process to form trench memory 130 in accordance with a second embodiment of the present invention wherein trench memory 130 has a pad layer 132 (e.g., silicon nitride) above a semiconductor (e.g., silicon) substrate 134 . Between pad layer 132 and semiconductor substrate 134 may be an underlying silicon oxide (SiO 2 ) layer (not shown). Formed into semiconductor substrate 134 is a trench 136 . Further formed, or deposited, in trench 136 is a node dielectric material 140 on a sidewall of trench 136 . Node dielectric material 140 may be silicon nitride, silicon dioxide, or other suitable dielectric material formed by thermal growth, sputtering, deposition, or other suitable techniques now known or later developed.
- a pad layer 132 e.g., silicon nitride
- semiconductor substrate 134 Between pad layer 132 and semiconductor substrate 134 may be an underlying silicon oxide (SiO 2 ) layer (not shown).
- SiO 2 silicon
- a first filling, or sacrificial, material 142 A is placed within trench 136 so as to abut node dielectric material 140 .
- First filling material 142 A may be spin on glass (SOG), resist, or other suitable polymer material.
- First filling material 142 A and node dielectric material 140 are recessed, or removed, partially from trench 136 so that first filling material 142 A and node dielectric material 140 are substantially at the same height.
- first filling material 142 A is removed in its entirety from trench 136 , such that node dielectric material 140 remains in lower portion of trench 136 .
- an insulating collar 138 is formed in an upper portion of trench 136 .
- Insulating collar 138 typically is made of silicon dioxide (SiO 2 ), silicon nitride (Si 3 N 4 ), or any suitable dielectric material by methods including oxidizing an exposed sidewall of trench 136 . In this manner, insulating collar 138 abuts node dielectric material 140 along side of trench 136 .
- a second filling, or sacrificial, material 142 B is placed within trench 136 so as to abut node dielectric material 140 and insulating collar 138 .
- second filling material 142 B may be spin on glass (SOG), resist, or other suitable polymer material.
- Second filling material 142 B is recessed, or removed, partially from trench 136 so as to expose a portion of insulating collar 138 , as shown in FIG. 4E .
- insulating collar 138 An exposed portion of insulating collar 138 (i.e., portion above second filling material 142 B) is removed from trench 136 ( FIG. 4F ). In one embodiment, insulating collar 138 and second filling material 42 B that remain are aligned so as to be substantially at the same height.
- second filling material 142 B is removed from trench 136 and a conducting material 152 is placed in trench 136 .
- Conducting material 152 may be placed so as to substantially, or completely, fill trench 136 .
- conducting material 152 is placed so that buried strap 146 ( FIG. 5 ) is contiguous to conducting material 152 .
- an upper portion of conducting material 152 is removed so as to make room for subsequent placement of STI 144 ( FIG. 5 ) above conducting material 152 .
- Conducting material 142 may be doped polysilicon, although other suitable conducting material such as a doped silicon germanium, a metal (e.g., tungsten, titanium, etc.) or an alloy (e.g., tungsten silicide, titanium nitride, etc.) may be used. Placement may be done in a fashion so that single conducting material 152 is monolithic within trench 136 , so that there exists no interfaces within conducting material 152 . Further, conducting material 152 may be placed in one temporal step, rather than three steps (or, in multiple steps), thereby reducing process time and cost.
- FIG. 5 depicts completed second embodiment of trench memory 130 (e.g., DRAM) wherein an upper portion of single conducting material 152 has been partially recessed and thereupon STI 144 has been formed.
- completed trench memory 130 includes a buried strap 146 that is contiguous with conducting material 152 . Further, the trench memory 130 has a lower resistance because there are interfaces within conducting material 152 .
- Completed trench memory (e.g., DRAM) 130 includes one capacitor 149 and one transistor (e.g., conventional MOSFET) 148 connected via a buried strap 146 to each other.
- Transistor 148 includes a gate conductor 150 , gate dielectric 152 , and a drain 154 and a source 156 on either side of gate conductor 150 .
Abstract
Description
- This divisional application claims priority to co-pending U.S. patent application Ser. No. 11/308,103 entitled TRENCH MEMORY WITH MONOLITHIC CONDUCTING MATERIAL AND METHODS FOR FORMING SAME, filed on Mar. 7, 2006, the contents of which are hereby incorporated by reference in their entirety.
- 1. Field of the Invention
- The present invention relates generally to manufacturing of a semiconductor device. More specifically, the present invention provides a method and apparatus for forming a trench memory, such as dynamic random access memory (DRAM), with a monolithic conducting material.
- 2. Background Art
- A trench memory, for example a dynamic random access memory (DRAM), is depicted, in cross-sectional view, in
FIG. 1 . As is typical the trench memory (e.g., DRAM) 1 has onecapacitor 2 and onetransistor 4 and further includes various constructs located within, or upon, asemiconductor substrate 6.Trench memory 1 includescapacitor 2, typically located within atrench 8, that is connected to a transistor (e.g., conventional MOSFET) 4 via a buriedstrap 10.Transistor 4 includes agate conductor 12, gate dielectric 14, and adrain 16 and asource 18 on either side ofgate conductor 12. - Lining a portion of
trench 8 is a node dielectric 20. Above node dielectric 20, also lining a portion oftrench 8 is an insulating collar 22 (or collar oxide). Also withintrench 8 is conductingmaterials collar 22 is a shallow trench isolation (STI) 26. - Due to the steps of constructing
trench memory 1 and its various parts,trench 8 is filled by three (3) polysilicon materials (i.e.,first poly 24A,second poly 24B, andthird poly 24C). Because threepoly materials trench 8 at temporally distinct times,poly materials materials material 24 intrench 8.First poly 24A is placed first.Second poly 24B is placed later, after placement offirst poly 24A and intermittent steps.Third poly 24C is placed later, after placement ofsecond poly 24B and other intermittent steps, as well. - Interfaces are created where each
poly 24 abuts anotheradjoining poly 24. For example, apoly 24 topoly 24 interface is created wherefirst poly 24A meetssecond poly 24B. Similarly, asecond poly 24 topoly 24 interface is created wheresecond poly 24B andthird poly 24C meet. A shortcoming of thistrench memory 1, and the method of making it, is that each interface increases the overall resistance oftrench 8, thereby causing a concomitant reduction in the overall performance oftrench memory 1. Further, there are several steps in placingfirst poly 24A,second poly 24B, andthird poly 24C, thereby increasing process time and cost. - In view of the foregoing, there exists a need for an improved process for constructing trench memory that overcomes the aforementioned deficiencies.
- A trench memory filled with a monolithic conducting material and methods for forming the same are disclosed. The trench memory includes a trench that has only a single, monolithic conducting material within the trench. The method includes forming a trench with a collar in the trench; forming a node dielectric on a sidewall of the trench; and filling the trench with a monolithic conducting material, such as polysilicon.
- A first aspect of the present invention provides a method of forming a trench memory, comprising the steps of: forming a trench with a collar in the trench; forming a node dielectric on a sidewall of the trench; and filling the trench with a monolithic conducting material.
- A second aspect of the present invention provides a trench memory comprising: a capacitor in a trench; a collar disposed above the capacitor; and an access transistor connected to the capacitor through a buried strap, wherein the trench is filled with a monolithic conducting material.
- A third aspect of the present invention provides a method of forming a trench memory comprising: forming a collar in an upper portion of a trench; forming a capacitor in a lower portion of the trench below the collar; and connecting a transistor to the capacitor, through a buried strap, wherein the trench is filled with a monolithic conducting material
- The illustrative aspects of the present invention are designed to solve the problems herein described and other problems not discussed, which are discoverable by a skilled artisan.
- These and other features of this invention will be more readily understood from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings in which:
-
FIG. 1 depicts a cross-sectional elevation view of a multiple poly fill trench memory in the related art. -
FIGS. 2A-2E depict cross-section elevation views of steps of forming a trench memory with monolithic conducting material, in accordance with a first embodiment of the present invention. -
FIG. 3 depicts a cross-sectional elevation view of a first embodiment of a completed trench memory with monolithic conducting material, in accordance with the present invention. -
FIGS. 4A-4G depict cross-section elevation views of steps of forming a trench memory with monolithic conducting material, in accordance with a second embodiment of the present invention. -
FIG. 5 depicts a cross-sectional elevation view of a second embodiment of a completed trench memory with monolithic conducting material, in accordance with the present invention. - The drawings are merely schematic representations, not intended to portray specific parameters of the invention. The drawings are intended to depict only typical embodiments of the invention, and therefore should not be considered as limiting the scope of the invention. In the drawings, like numbering represents like elements.
- As indicated above, the present invention provides a trench memory with monolithic conducting material and methods of forming the trench memory with monolithic conducting material.
-
FIGS. 2A through 2E depict cross-section elevation views of atrench memory 30 undergoing the various steps of constructing a trench memory with monolithic conducting material in accordance with a first embodiment of the present invention.FIG. 3 depicts the finished first embodiment (i.e., completed trench memory 30). - Similarly,
FIGS. 4A through 4G depict cross-section elevation views of various steps of forming oftrench memory 130 with a monolithic conductive material in accordance with a second embodiment of the present invention.FIG. 5 depicts a finished second embodiment (i.e., completed trench memory 130). - Returning to
FIGS. 2A-2E ,FIG. 2A shows the starting of a process to formtrench memory 30 in a first embodiment of the present invention whereintrench memory 30 has a pad layer 32 (e.g., silicon nitride) above a semiconductor (e.g., silicon)substrate 34. Betweenpad layer 32 andsemiconductor substrate 34 may be an underlying silicon dioxide (SiO2) layer (not shown). Formed intosemiconductor substrate 34 is atrench 36. Further formed in the upper portion oftrench 36 is aninsulating collar 38 typically made of silicon dioxide (SiO2), silicon nitride (Si3N4), or any suitable dielectric material. Methods for forming aninsulating collar 38 inupper trench 36 are well known in the art and therefore are not described in detail in order to avoid obscuring the invention. -
FIG. 2B follows wherein anode dielectric material 40 is formed, or deposited, on sidewall oftrench 36.Node dielectric material 40 may be silicon nitride (Si3N4), silicon dioxide (SiO2), or other suitable dielectric material formed by thermal growth, sputtering, deposition, or other suitable techniques. Subsequently, a fillingmaterial 42 is placed withintrench 36 so as to abutnode dielectric material 40. Fillingmaterial 42 may be spin on glass (SOG), resist, or other suitable material. Fillingmaterial 42 is recessed, or removed, partially fromtrench 36 to a point along insulatingcollar 38 by any conventional recess process such as reactive ion etch (RIE), chemical downstream etch (CDE), or other suitable etch techniques now known or later developed. - In
FIG. 2C portions ofnode dielectric material 40 and insulating collar 38 (i.e., portion above filling material 42) are removed fromtrench 36. Thus, insulatingcollar 38,dielectric material 40, and fillingmaterial 42 that remain withintrench 36 are substantially at the same height intrench 36. - Subsequently, filling material 42 (
FIG. 2C ) is removed in its entirety fromtrench 36, such that insulatingcollar 38 anddielectric material 40 remains intrench 36 as shown inFIG. 2D . Removal techniques may include RIE, CDE, wet etch and other suitable removal techniques now known or later developed. -
FIG. 2E follows wherein a conductingmaterial 52 is placed intrench 36. Placement techniques may include chemical vapor deposition (CVD), atomic layer deposition (ALD), physical vapor deposition (PVD), sputtering, plating, and other suitable techniques now known or later developed. Conductingmaterial 52 may be placed so as to substantially, or completely, filltrench 36. In an embodiment wheretrench 36 is filled less than its entire depth (i.e., substantial filling), conductingmaterial 52 is placed intrench 36 to an amount so as to abut, or adjoin, adjacent buried strap 46 (FIG. 3 ), so as to create connectivity between conductingmaterial 52 and buriedstrap 46. In an embodiment wheretrench 36 is completely filled with conductingmaterial 52, in a subsequent step, an upper portion of conductingmaterial 52 may be removed so as to make room for subsequent placement of shallow trench isolation (STI) 44 (FIG. 3 ) above remaining conductingmaterial 52. Conductingmaterial 52 may be doped polysilicon, although other suitable conducting material such as a doped silicon germanium, a metal (e.g., tungsten, titanium, etc.) or an alloy (e.g., tungsten silicide, titanium nitride, etc.). Placement may be done in a monolithic fashion so that single conductingmaterial 52 is a single piece; so that there exists no interfaces in conductingmaterial 52. Further, conductingmaterial 52 may be placed in one temporal step, rather than three steps (or, in multiple steps), thereby reducing process time and cost. -
FIG. 3 depicts a first embodiment of a finished trench memory 30 (e.g., DRAM) wherein an upper portion ofsingle conducting material 52 has been partially recessed and thereuponSTI 44 has been formed. As a result, completedtrench memory 30 includes a buriedstrap 46 that is contiguous with monolithic conductingmaterial 52. Further,trench memory 30 has a lower, and thereby improved, resistance because there are no interfaces within conductingmaterial 52. Completed trench memory (e.g., DRAM) 30 includes onecapacitor 49 and one transistor (e.g., conventional MOSFET) 48 connected via a buriedstrap 46 to each other.Transistor 48 includes agate conductor 50,gate dielectric 52, and adrain 54 and asource 56 on either side ofgate conductor 50. -
FIG. 4A shows the starting of a process to formtrench memory 130 in accordance with a second embodiment of the present invention whereintrench memory 130 has a pad layer 132 (e.g., silicon nitride) above a semiconductor (e.g., silicon)substrate 134. Betweenpad layer 132 andsemiconductor substrate 134 may be an underlying silicon oxide (SiO2) layer (not shown). Formed intosemiconductor substrate 134 is atrench 136. Further formed, or deposited, intrench 136 is anode dielectric material 140 on a sidewall oftrench 136.Node dielectric material 140 may be silicon nitride, silicon dioxide, or other suitable dielectric material formed by thermal growth, sputtering, deposition, or other suitable techniques now known or later developed. - In a second step (
FIG. 4B ), a first filling, or sacrificial,material 142A is placed withintrench 136 so as to abutnode dielectric material 140. First fillingmaterial 142A may be spin on glass (SOG), resist, or other suitable polymer material. First fillingmaterial 142A andnode dielectric material 140 are recessed, or removed, partially fromtrench 136 so that first fillingmaterial 142A andnode dielectric material 140 are substantially at the same height. - Then, as shown in
FIG. 4C , first fillingmaterial 142A is removed in its entirety fromtrench 136, such thatnode dielectric material 140 remains in lower portion oftrench 136. - Upon removal of
first filling material 142A fromtrench 136, an insulatingcollar 138 is formed in an upper portion oftrench 136. Insulatingcollar 138 typically is made of silicon dioxide (SiO2), silicon nitride (Si3N4), or any suitable dielectric material by methods including oxidizing an exposed sidewall oftrench 136. In this manner, insulatingcollar 138 abutsnode dielectric material 140 along side oftrench 136. - A second filling, or sacrificial,
material 142B is placed withintrench 136 so as to abutnode dielectric material 140 and insulatingcollar 138. Similarly,second filling material 142B may be spin on glass (SOG), resist, or other suitable polymer material.Second filling material 142B is recessed, or removed, partially fromtrench 136 so as to expose a portion of insulatingcollar 138, as shown inFIG. 4E . - An exposed portion of insulating collar 138 (i.e., portion above
second filling material 142B) is removed from trench 136 (FIG. 4F ). In one embodiment, insulatingcollar 138 and second filling material 42B that remain are aligned so as to be substantially at the same height. - In a penultimate step, as shown in
FIG. 4G ,second filling material 142B is removed fromtrench 136 and a conductingmaterial 152 is placed intrench 136. Conductingmaterial 152 may be placed so as to substantially, or completely, filltrench 136. In an embodiment, wheretrench 136 is substantially filled, conductingmaterial 152 is placed so that buried strap 146 (FIG. 5 ) is contiguous to conductingmaterial 152. Contrastingly, when conductingmaterial 152 is be placed intrench 136 to completely filltrench 136, in a subsequent step an upper portion of conductingmaterial 152 is removed so as to make room for subsequent placement of STI 144 (FIG. 5 ) above conductingmaterial 152. Conducting material 142 may be doped polysilicon, although other suitable conducting material such as a doped silicon germanium, a metal (e.g., tungsten, titanium, etc.) or an alloy (e.g., tungsten silicide, titanium nitride, etc.) may be used. Placement may be done in a fashion so thatsingle conducting material 152 is monolithic withintrench 136, so that there exists no interfaces within conductingmaterial 152. Further, conductingmaterial 152 may be placed in one temporal step, rather than three steps (or, in multiple steps), thereby reducing process time and cost. -
FIG. 5 depicts completed second embodiment of trench memory 130 (e.g., DRAM) wherein an upper portion ofsingle conducting material 152 has been partially recessed and thereuponSTI 144 has been formed. As a result completedtrench memory 130 includes a buriedstrap 146 that is contiguous with conductingmaterial 152. Further, thetrench memory 130 has a lower resistance because there are interfaces within conductingmaterial 152. Completed trench memory (e.g., DRAM) 130 includes onecapacitor 149 and one transistor (e.g., conventional MOSFET) 148 connected via a buriedstrap 146 to each other.Transistor 148 includes agate conductor 150,gate dielectric 152, and adrain 154 and asource 156 on either side ofgate conductor 150. - The foregoing description of the preferred embodiments of this invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and obviously, many modifications and variations are possible. Such modifications and variations that may be apparent to a person skilled in the art are intended to be included within the scope of this invention as defined by the accompanying claims.
Claims (5)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US12/348,939 US20090108315A1 (en) | 2006-03-07 | 2009-01-06 | Trench memory with monolithic conducting material and methods for forming same |
Applications Claiming Priority (2)
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US11/308,103 US7491604B2 (en) | 2006-03-07 | 2006-03-07 | Trench memory with monolithic conducting material and methods for forming same |
US12/348,939 US20090108315A1 (en) | 2006-03-07 | 2009-01-06 | Trench memory with monolithic conducting material and methods for forming same |
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US11/308,103 Division US7491604B2 (en) | 2006-03-07 | 2006-03-07 | Trench memory with monolithic conducting material and methods for forming same |
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US20090108315A1 true US20090108315A1 (en) | 2009-04-30 |
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US12/348,939 Abandoned US20090108315A1 (en) | 2006-03-07 | 2009-01-06 | Trench memory with monolithic conducting material and methods for forming same |
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Also Published As
Publication number | Publication date |
---|---|
US7491604B2 (en) | 2009-02-17 |
US20070212830A1 (en) | 2007-09-13 |
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