US20100276764A1 - Semiconductor structure with selectively deposited tungsten film and method for making the same - Google Patents
Semiconductor structure with selectively deposited tungsten film and method for making the same Download PDFInfo
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- US20100276764A1 US20100276764A1 US12/434,688 US43468809A US2010276764A1 US 20100276764 A1 US20100276764 A1 US 20100276764A1 US 43468809 A US43468809 A US 43468809A US 2010276764 A1 US2010276764 A1 US 2010276764A1
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- 239000004065 semiconductor Substances 0.000 title claims abstract description 30
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 title claims description 20
- 229910052721 tungsten Inorganic materials 0.000 title claims description 20
- 239000010937 tungsten Substances 0.000 title claims description 20
- 238000000034 method Methods 0.000 title description 18
- 229910052751 metal Inorganic materials 0.000 claims abstract description 35
- 239000002184 metal Substances 0.000 claims abstract description 35
- 239000004020 conductor Substances 0.000 claims abstract description 21
- 239000000758 substrate Substances 0.000 claims abstract description 15
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 7
- NRTOMJZYCJJWKI-UHFFFAOYSA-N Titanium nitride Chemical compound [Ti]#N NRTOMJZYCJJWKI-UHFFFAOYSA-N 0.000 claims description 7
- 229910052710 silicon Inorganic materials 0.000 claims description 7
- 239000010703 silicon Substances 0.000 claims description 7
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 3
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 3
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 3
- 229910052782 aluminium Inorganic materials 0.000 claims description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 3
- 229910052802 copper Inorganic materials 0.000 claims description 3
- 239000010949 copper Substances 0.000 claims description 3
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 3
- 239000010931 gold Substances 0.000 claims description 3
- 229910052737 gold Inorganic materials 0.000 claims description 3
- 229910021332 silicide Inorganic materials 0.000 claims description 3
- FVBUAEGBCNSCDD-UHFFFAOYSA-N silicide(4-) Chemical compound [Si-4] FVBUAEGBCNSCDD-UHFFFAOYSA-N 0.000 claims description 3
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 3
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 3
- 229910052715 tantalum Inorganic materials 0.000 claims description 3
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 claims description 3
- MZLGASXMSKOWSE-UHFFFAOYSA-N tantalum nitride Chemical compound [Ta]#N MZLGASXMSKOWSE-UHFFFAOYSA-N 0.000 claims description 3
- 239000010936 titanium Substances 0.000 claims description 3
- 229910052719 titanium Inorganic materials 0.000 claims description 3
- 238000000231 atomic layer deposition Methods 0.000 description 8
- 238000000151 deposition Methods 0.000 description 8
- 238000010586 diagram Methods 0.000 description 5
- 238000005229 chemical vapour deposition Methods 0.000 description 4
- 239000010408 film Substances 0.000 description 4
- 239000001257 hydrogen Substances 0.000 description 4
- 229910052739 hydrogen Inorganic materials 0.000 description 4
- 238000001020 plasma etching Methods 0.000 description 4
- 239000010409 thin film Substances 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- NXHILIPIEUBEPD-UHFFFAOYSA-H tungsten hexafluoride Chemical compound F[W](F)(F)(F)(F)F NXHILIPIEUBEPD-UHFFFAOYSA-H 0.000 description 2
- 238000001039 wet etching Methods 0.000 description 2
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000001459 lithography Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 1
- 229920005591 polysilicon Polymers 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 238000004886 process control Methods 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000010926 purge Methods 0.000 description 1
- 229910000077 silane Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
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- H—ELECTRICITY
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- H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/40—Electrodes ; Multistep manufacturing processes therefor
- H01L29/43—Electrodes ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
- H01L29/49—Metal-insulator-semiconductor electrodes, e.g. gates of MOSFET
- H01L29/4983—Metal-insulator-semiconductor electrodes, e.g. gates of MOSFET with a lateral structure, e.g. a Polysilicon gate with a lateral doping variation or with a lateral composition variation or characterised by the sidewalls being composed of conductive, resistive or dielectric material
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- H—ELECTRICITY
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- 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
- H01L21/28—Manufacture of electrodes on semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/268
- H01L21/28008—Making conductor-insulator-semiconductor electrodes
- H01L21/28017—Making conductor-insulator-semiconductor electrodes the insulator being formed after the semiconductor body, the semiconductor being silicon
- H01L21/28026—Making conductor-insulator-semiconductor electrodes the insulator being formed after the semiconductor body, the semiconductor being silicon characterised by the conductor
- H01L21/28079—Making conductor-insulator-semiconductor electrodes the insulator being formed after the semiconductor body, the semiconductor being silicon characterised by the conductor the final conductor layer next to the insulator being a single metal, e.g. Ta, W, Mo, Al
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- 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
- H01L21/28—Manufacture of electrodes on semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/268
- H01L21/28008—Making conductor-insulator-semiconductor electrodes
- H01L21/28017—Making conductor-insulator-semiconductor electrodes the insulator being formed after the semiconductor body, the semiconductor being silicon
- H01L21/28026—Making conductor-insulator-semiconductor electrodes the insulator being formed after the semiconductor body, the semiconductor being silicon characterised by the conductor
- H01L21/28088—Making conductor-insulator-semiconductor electrodes the insulator being formed after the semiconductor body, the semiconductor being silicon characterised by the conductor the final conductor layer next to the insulator being a composite, e.g. TiN
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- 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
- H01L21/28—Manufacture of electrodes on semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/268
- H01L21/28008—Making conductor-insulator-semiconductor electrodes
- H01L21/28017—Making conductor-insulator-semiconductor electrodes the insulator being formed after the semiconductor body, the semiconductor being silicon
- H01L21/28026—Making conductor-insulator-semiconductor electrodes the insulator being formed after the semiconductor body, the semiconductor being silicon characterised by the conductor
- H01L21/28105—Making conductor-insulator-semiconductor electrodes the insulator being formed after the semiconductor body, the semiconductor being silicon characterised by the conductor the final conductor next to the insulator having a lateral composition or doping variation, or being formed laterally by more than one deposition step
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- 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
- H01L21/28—Manufacture of electrodes on semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/268
- H01L21/283—Deposition of conductive or insulating materials for electrodes conducting electric current
- H01L21/285—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation
- H01L21/28506—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation of conductive layers
- H01L21/28512—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation of conductive layers on semiconductor bodies comprising elements of Group IV of the Periodic System
- H01L21/28556—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation of conductive layers on semiconductor bodies comprising elements of Group IV of the Periodic System by chemical means, e.g. CVD, LPCVD, PECVD, laser CVD
- H01L21/28562—Selective deposition
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- H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
- H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
- H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
- H01L21/76838—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the conductors
- H01L21/76841—Barrier, adhesion or liner layers
- H01L21/7685—Barrier, adhesion or liner layers the layer covering a conductive structure
- H01L21/76852—Barrier, adhesion or liner layers the layer covering a conductive structure the layer also covering the sidewalls of the conductive structure
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- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/52—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames
- H01L23/522—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames including external interconnections consisting of a multilayer structure of conductive and insulating layers inseparably formed on the semiconductor body
- H01L23/532—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames including external interconnections consisting of a multilayer structure of conductive and insulating layers inseparably formed on the semiconductor body characterised by the materials
- H01L23/53204—Conductive materials
- H01L23/53209—Conductive materials based on metals, e.g. alloys, metal silicides
- H01L23/53257—Conductive materials based on metals, e.g. alloys, metal silicides the principal metal being a refractory metal
- H01L23/53266—Additional layers associated with refractory-metal layers, e.g. adhesion, barrier, cladding layers
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- H—ELECTRICITY
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- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/40—Electrodes ; Multistep manufacturing processes therefor
- H01L29/43—Electrodes ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
- H01L29/49—Metal-insulator-semiconductor electrodes, e.g. gates of MOSFET
- H01L29/495—Metal-insulator-semiconductor electrodes, e.g. gates of MOSFET the conductor material next to the insulator being a simple metal, e.g. W, Mo
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/40—Electrodes ; Multistep manufacturing processes therefor
- H01L29/43—Electrodes ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
- H01L29/49—Metal-insulator-semiconductor electrodes, e.g. gates of MOSFET
- H01L29/4966—Metal-insulator-semiconductor electrodes, e.g. gates of MOSFET the conductor material next to the insulator being a composite material, e.g. organic material, TiN, MoSi2
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- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/0001—Technical content checked by a classifier
- H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
Definitions
- the present invention relates generally to semiconductor technology and, more particularly, to a semiconductor structure, e.g. a metal gate or a word line of a vertical-channel transistor, and a method for making the same.
- a semiconductor structure e.g. a metal gate or a word line of a vertical-channel transistor
- Selective deposition methods such as selective chemical vapor deposition (CVD) processes are known in the art.
- Selective deposition may be used to deposit materials on selected surfaces of structures in the manufacture of integrated circuits, and thus obviates the need for associated lithography, etching, and resist removal steps.
- Selective CVD processes are advantageous because they allow for self-alignment with respect to various structures, thus allowing for relatively tight design rules.
- the prior art selective deposition methods still have some drawbacks.
- the prior art selective deposition methods are often used to grow tungsten layer in a contact hole. Prior to the deposition or growth of the tungsten in the contact hole, a series of cleaning steps are required to ensure the silicon surface cleanness. If Reactive Ion Etching (RIE) damage layer exists on the bottom of the contact hole, the metal film formed by the selective CVD process does not grow because the RIE damage layer may work as an insulating film. Therefore, the RIE damage layer needs to be removed before growth of the metal film.
- RIE Reactive Ion Etching
- the prior art selective deposition methods are apparently not able to provide a selectively deposited layer such as tungsten layer, which is not only a conformal, ultra-thin (below 15 nm) film but structurally continuous, on a metallic, non-silicon base layer. Also, it is difficult to maintain sufficiently high selectivity between dielectric layer and metal base layer and to deposit such conformal, ultra-thin film at the same time.
- a semiconductor structure includes a substrate; a dielectric layer overlying the substrate; a conductor pattern on a main surface of the dielectric layer, the conductor pattern having a top surface and sidewalls; and a conformal metal layer selectively deposited on the top surface and sidewalls, but without deposited on the main surface of the dielectric layer substantially.
- a method for forming a semiconductor structure includes providing a substrate; forming a dielectric layer on the substrate; forming a conductor pattern on a main surface of the dielectric layer, the conductor pattern having a top surface and sidewalls; and performing a selective atomic layer deposition (ALD) process to selectively deposit a conformal metal layer onto the top surface and sidewalls of the conductor pattern, but without depositing onto the main surface of the dielectric layer substantially.
- ALD selective atomic layer deposition
- FIG. 1 is a schematic, cross-sectional diagram illustrating a semiconductor structure of an integrated circuit in accordance with one preferred embodiment of this invention.
- FIG. 2 is a flow diagram of a method for making a semiconductor structure of FIG. 1 in accordance with the preferred embodiment of this invention.
- FIG. 1 is a schematic, cross-sectional diagram illustrating a semiconductor structure of an integrated circuit in accordance with one preferred embodiment of this invention.
- the semiconductor structure 1 comprises a semiconductor substrate 10 such as silicon substrate, a dielectric layer 12 on the semiconductor substrate 10 , a conductor pattern 14 formed on a main surface 12 a of the dielectric layer 12 , and an ultra-thin metal layer 16 selectively deposited on a top surface 14 a and sidewalls 14 b of the conductor pattern 14 .
- the metal layer 16 is not deposited or grown directly on the main surface 12 a of the dielectric layer 12 .
- the semiconductor structure 1 may be a metal-gated transistor device and the dielectric layer 12 is a gate dielectric layer or gate oxide layer of the metal-gated transistor device.
- This invention is particularly suited for a metal-gated vertical-channel transistor device.
- Such vertical-channel transistor device may be used in advanced dynamic random access memory (DRAM) technology, wherein the metal layer 16 is capable of reducing the resistance of the word lines. Further, it is often required that the metal layer 16 is ultra thin (below 15 nm) and is a continuous and conformal layer for the concern of work function of the metal-gated transistor device.
- DRAM dynamic random access memory
- the dielectric layer 12 comprises silicon oxide, silicon nitride or silicon oxy-nitride.
- the conductor pattern 14 comprises titanium, titanium nitride, tantalum, tantalum nitride, aluminum, copper, gold, tungsten, silicide or any combination thereof.
- the conductor pattern 14 is made of titanium nitride and the metal layer 16 is an atomic layer deposited tungsten layer having a thickness of less than 15 nanometers.
- the conductor pattern 14 which may be part of a metal gate or word line, has a thickness of less than 15 nanometers, more preferably, in a range of about 6-8 nanometers.
- FIG. 2 is a flow diagram of a method 20 for making a semiconductor structure of FIG. 1 in accordance with the preferred embodiment of this invention.
- a semiconductor substrate such as the substrate 10 depicted in FIG. 1 is provided.
- a dielectric layer such as the dielectric layer 12 depicted in FIG. 1 is thermally grown on the semiconductor substrate.
- the dielectric layer comprises silicon oxide, silicon nitride or silicon oxy-nitride.
- a metal pattern such as the conductor pattern 14 depicted in FIG. 1 is formed on the main surface of the dielectric layer.
- the metal pattern comprises titanium, titanium nitride, tantalum, tantalum nitride, aluminum, copper, gold, tungsten, silicide or any combination thereof.
- the metal pattern is titanium nitride and the metal pattern is defined by wet etching methods.
- a metal layer such as a titanium nitride layer is capped with a mask layer such as a polysilicon layer.
- the mask layer only mask a top surface of the metal layer but exposes sidewalls of the metal layer.
- a wet etching process is then carried out to etch the sidewalls of the metal layer to define the metal pattern.
- the mask layer is then removed to expose the top surface of the metal pattern.
- a selective tungsten atomic layer deposition process is carried out to grow a conformal, ultra-thin tungsten layer such as the metal layer 16 depicted in FIG. 1 on the metal pattern.
- the conformal, ultra-thin tungsten layer has a thickness of less than 15 nm and has good step coverage characteristic.
- the selective tungsten atomic layer deposition process may involve a plurality of ALD cycles to achieve a desired thickness of the tungsten layer on the metal pattern. For the sake of simplicity, merely one of the ALD cycles (Steps 24 - 27 ) is illustrated in the flow diagram in FIG. 2 .
- the ALD cycle includes: (1) flowing hydrogen-containing substance such as silane or hydrogen gas into a chamber for a period of time to adsorb hydrogen radicals on the main surface of the dielectric layer and on the metal pattern (Step 24 ); (2) pumping down the chamber while stopping all gas flow to selectively remove the hydrogen radicals merely from the main surface of the dielectric layer (Step 25 ); (3) flowing tungsten precursor such as tungsten hexafluoride (WF 6 ) into the chamber at a low pressure (below 5 torr) and low temperature (below 300° C.) to react with the remanent hydrogen radicals adsorbed merely on the metal pattern, thereby selectively depositing a tungsten layer thereto (Step 26 ); and ( 4 ) purging the chamber with inert gas such as argen to remove by-products (Step 27 ). It is understood that the desired thickness of the tungsten layer can be achieved by repeating the ALD cycle (Step 28 ).
- hydrogen-containing substance such as silane
Abstract
A semiconductor structure is provided. The semiconductor structure includes a substrate; a dielectric layer overlying the substrate; a conductor pattern on a main surface of the dielectric layer, the conductor pattern having a top surface and sidewalls; and a conformal metal layer selectively deposited on the top surface and sidewalls, but without deposited on the main surface of the dielectric layer substantially.
Description
- 1. Field of the Invention
- The present invention relates generally to semiconductor technology and, more particularly, to a semiconductor structure, e.g. a metal gate or a word line of a vertical-channel transistor, and a method for making the same.
- 2. Description of the Prior Art
- As circuit integration increases, the need for greater uniformity and process control regarding layer thickness rises. Various technologies have been developed to deposit layers on substrates in a cost-effective manner, while maintaining control over the characteristics of the layer.
- Selective deposition methods such as selective chemical vapor deposition (CVD) processes are known in the art. Selective deposition may be used to deposit materials on selected surfaces of structures in the manufacture of integrated circuits, and thus obviates the need for associated lithography, etching, and resist removal steps. Selective CVD processes are advantageous because they allow for self-alignment with respect to various structures, thus allowing for relatively tight design rules.
- However, the prior art selective deposition methods still have some drawbacks. For example, the prior art selective deposition methods are often used to grow tungsten layer in a contact hole. Prior to the deposition or growth of the tungsten in the contact hole, a series of cleaning steps are required to ensure the silicon surface cleanness. If Reactive Ion Etching (RIE) damage layer exists on the bottom of the contact hole, the metal film formed by the selective CVD process does not grow because the RIE damage layer may work as an insulating film. Therefore, the RIE damage layer needs to be removed before growth of the metal film.
- In addition, the prior art selective deposition methods are apparently not able to provide a selectively deposited layer such as tungsten layer, which is not only a conformal, ultra-thin (below 15 nm) film but structurally continuous, on a metallic, non-silicon base layer. Also, it is difficult to maintain sufficiently high selectivity between dielectric layer and metal base layer and to deposit such conformal, ultra-thin film at the same time.
- In light of the above, there is a need in this industry to provide an improved semiconductor structure and method for making the same, where a conformal, ultra-thin film is desired and the conformal, ultra-thin film can be selectively deposited on a metallic, non-silicon base layer with high selectivity between dielectric layer and metal base layer. It is also desirable to provide a method for making such conformal, ultra-thin film with higher throughput.
- It is one objective of this invention to provide an improved semiconductor structure, e.g. a metal gate or a word line of a vertical-channel transistor, and a method for making the same in order to solve the above-mentioned prior art problems.
- According to one aspect of this invention, a semiconductor structure is provided. The semiconductor structure includes a substrate; a dielectric layer overlying the substrate; a conductor pattern on a main surface of the dielectric layer, the conductor pattern having a top surface and sidewalls; and a conformal metal layer selectively deposited on the top surface and sidewalls, but without deposited on the main surface of the dielectric layer substantially.
- According to another aspect of this invention, a method for forming a semiconductor structure is provided. The method includes providing a substrate; forming a dielectric layer on the substrate; forming a conductor pattern on a main surface of the dielectric layer, the conductor pattern having a top surface and sidewalls; and performing a selective atomic layer deposition (ALD) process to selectively deposit a conformal metal layer onto the top surface and sidewalls of the conductor pattern, but without depositing onto the main surface of the dielectric layer substantially.
- These and other objectives of the present invention will no doubt come obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
-
FIG. 1 is a schematic, cross-sectional diagram illustrating a semiconductor structure of an integrated circuit in accordance with one preferred embodiment of this invention. -
FIG. 2 is a flow diagram of a method for making a semiconductor structure ofFIG. 1 in accordance with the preferred embodiment of this invention. -
FIG. 1 is a schematic, cross-sectional diagram illustrating a semiconductor structure of an integrated circuit in accordance with one preferred embodiment of this invention. As shown inFIG. 1 , the semiconductor structure 1 comprises asemiconductor substrate 10 such as silicon substrate, adielectric layer 12 on thesemiconductor substrate 10, aconductor pattern 14 formed on amain surface 12 a of thedielectric layer 12, and anultra-thin metal layer 16 selectively deposited on atop surface 14 a andsidewalls 14 b of theconductor pattern 14. Substantially, themetal layer 16 is not deposited or grown directly on themain surface 12 a of thedielectric layer 12. - According to this invention, the semiconductor structure 1 may be a metal-gated transistor device and the
dielectric layer 12 is a gate dielectric layer or gate oxide layer of the metal-gated transistor device. This invention is particularly suited for a metal-gated vertical-channel transistor device. Such vertical-channel transistor device may be used in advanced dynamic random access memory (DRAM) technology, wherein themetal layer 16 is capable of reducing the resistance of the word lines. Further, it is often required that themetal layer 16 is ultra thin (below 15 nm) and is a continuous and conformal layer for the concern of work function of the metal-gated transistor device. - In accordance with the preferred embodiment of this invention, the
dielectric layer 12 comprises silicon oxide, silicon nitride or silicon oxy-nitride. Theconductor pattern 14 comprises titanium, titanium nitride, tantalum, tantalum nitride, aluminum, copper, gold, tungsten, silicide or any combination thereof. Preferably, theconductor pattern 14 is made of titanium nitride and themetal layer 16 is an atomic layer deposited tungsten layer having a thickness of less than 15 nanometers. Preferably, theconductor pattern 14, which may be part of a metal gate or word line, has a thickness of less than 15 nanometers, more preferably, in a range of about 6-8 nanometers. - Please refer to
FIG. 2 .FIG. 2 is a flow diagram of amethod 20 for making a semiconductor structure ofFIG. 1 in accordance with the preferred embodiment of this invention. As shown inFIG. 2 , in Step 21, a semiconductor substrate such as thesubstrate 10 depicted inFIG. 1 is provided. InStep 22, a dielectric layer such as thedielectric layer 12 depicted inFIG. 1 is thermally grown on the semiconductor substrate. The dielectric layer comprises silicon oxide, silicon nitride or silicon oxy-nitride. - In
Step 23, a metal pattern such as theconductor pattern 14 depicted inFIG. 1 is formed on the main surface of the dielectric layer. The metal pattern comprises titanium, titanium nitride, tantalum, tantalum nitride, aluminum, copper, gold, tungsten, silicide or any combination thereof. Preferably, the metal pattern is titanium nitride and the metal pattern is defined by wet etching methods. For example, a metal layer such as a titanium nitride layer is capped with a mask layer such as a polysilicon layer. The mask layer only mask a top surface of the metal layer but exposes sidewalls of the metal layer. A wet etching process is then carried out to etch the sidewalls of the metal layer to define the metal pattern. The mask layer is then removed to expose the top surface of the metal pattern. - After the formation of the metal pattern, a selective tungsten atomic layer deposition process is carried out to grow a conformal, ultra-thin tungsten layer such as the
metal layer 16 depicted inFIG. 1 on the metal pattern. According to this invention, the conformal, ultra-thin tungsten layer has a thickness of less than 15 nm and has good step coverage characteristic. The selective tungsten atomic layer deposition process may involve a plurality of ALD cycles to achieve a desired thickness of the tungsten layer on the metal pattern. For the sake of simplicity, merely one of the ALD cycles (Steps 24-27) is illustrated in the flow diagram inFIG. 2 . - According to the preferred embodiment of this invention, the ALD cycle includes: (1) flowing hydrogen-containing substance such as silane or hydrogen gas into a chamber for a period of time to adsorb hydrogen radicals on the main surface of the dielectric layer and on the metal pattern (Step 24); (2) pumping down the chamber while stopping all gas flow to selectively remove the hydrogen radicals merely from the main surface of the dielectric layer (Step 25); (3) flowing tungsten precursor such as tungsten hexafluoride (WF6) into the chamber at a low pressure (below 5 torr) and low temperature (below 300° C.) to react with the remanent hydrogen radicals adsorbed merely on the metal pattern, thereby selectively depositing a tungsten layer thereto (Step 26); and (4) purging the chamber with inert gas such as argen to remove by-products (Step 27). It is understood that the desired thickness of the tungsten layer can be achieved by repeating the ALD cycle (Step 28).
- Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention.
Claims (11)
1. A semiconductor structure, comprising:
a substrate;
a dielectric layer overlying the substrate;
a conductor pattern on a main surface of the dielectric layer, the conductor pattern having a top surface and sidewalls; and
a tungsten metal layer encompassing the conductor pattern including the top surface and the sidewalls, while leaving the main surface of the dielectric layer substantially free of the tungsten metal layer.
2. The semiconductor structure according to claim 1 wherein the dielectric layer comprises silicon oxide, silicon nitride or silicon oxy-nitride.
3. The semiconductor structure according to claim 1 wherein the conductor pattern comprises titanium, titanium nitride, tantalum, tantalum nitride, aluminum, copper, gold, tungsten, silicide or any combination thereof.
4. (canceled)
5. The semiconductor structure according to claim 1 wherein the conductor pattern is made of titanium nitride.
6. The semiconductor structure according to claim 5 wherein the metal layer is a tungsten layer.
7. The semiconductor structure according to claim 6 wherein the tungsten layer has a thickness of less than 15 nanometers.
8. The semiconductor structure according to claim 1 wherein the dielectric layer is a gate dielectric layer of a vertical-channel transistor.
9. The semiconductor structure according to claim 8 wherein the conductor pattern is part of a metal gate or a word line.
10. The semiconductor structure according to claim 9 wherein the conductor pattern has a thickness of less than 15 nanometers.
11. The semiconductor structure according to claim 9 wherein the conductor pattern has a thickness of about 6-8 nanometers.
Priority Applications (4)
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US12/434,688 US20100276764A1 (en) | 2009-05-04 | 2009-05-04 | Semiconductor structure with selectively deposited tungsten film and method for making the same |
TW98120620A TWI471938B (en) | 2009-05-04 | 2009-06-19 | Method for making semiconductor structure |
CN2009101517298A CN101882610B (en) | 2009-05-04 | 2009-07-13 | Semiconductor structure and manufacturing method thereof |
US12/815,407 US8003528B2 (en) | 2009-05-04 | 2010-06-15 | Semiconductor structure and method for making the same |
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US12/434,688 US20100276764A1 (en) | 2009-05-04 | 2009-05-04 | Semiconductor structure with selectively deposited tungsten film and method for making the same |
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US12/434,688 Abandoned US20100276764A1 (en) | 2009-05-04 | 2009-05-04 | Semiconductor structure with selectively deposited tungsten film and method for making the same |
US12/815,407 Active 2029-05-20 US8003528B2 (en) | 2009-05-04 | 2010-06-15 | Semiconductor structure and method for making the same |
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US9460932B2 (en) * | 2013-11-11 | 2016-10-04 | Applied Materials, Inc. | Surface poisoning using ALD for high selectivity deposition of high aspect ratio features |
US9659864B2 (en) | 2015-10-20 | 2017-05-23 | Taiwan Semiconductor Manufacturing Company, Ltd. | Method and apparatus for forming self-aligned via with selectively deposited etching stop layer |
US20200006274A1 (en) * | 2018-06-29 | 2020-01-02 | Powertech Technology Inc. | Semiconductor package and manufacturing method thereof |
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Also Published As
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TW201041041A (en) | 2010-11-16 |
CN101882610A (en) | 2010-11-10 |
US20100279498A1 (en) | 2010-11-04 |
CN101882610B (en) | 2012-01-18 |
TWI471938B (en) | 2015-02-01 |
US8003528B2 (en) | 2011-08-23 |
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