EP0437110A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Tungsten deposition process for low contact resistivity to silicon
Assignee: LSI Corp
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Filing: 1990-12-28
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Granted: —
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Expires: 2010-12-28
Abstract
Abstract In a method of forming a barrier layer for contacting a metal interconnect layer to one or more exposed N and p type silicon regions on a wafer, the wafer is heated with a direct radiation source, such as a lamp. To equalize the differing emissivities of the N type and P type silicon regions, an opaque layer of refractory metal is first formed on the regions at a temperature below approximately 100°C. A refractory metal deposition process is then conducted at temperatures between 230°C-425°C. During this higher temperature deposition process, the reducing gas is ramped up with time to increase the deposition rate of the refractory metal as the exothermic reducing reactions increasingly heat the contact areas. Other process and apparatus features enable higher bonding strength between the silicon surface and the formed barrier layer contacting the silicon surface and enable a higher purity content of the processing gases as well as improved diffusion of processing gases when injected into the processing chamber.
Inventors
- 👤 Keith J. Hansen
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 13:50
CPC Classifications
C; C23; C23C; C23C16/00; C23C16/44; C23C16/455; C23C16/45523; C23C16/04; C23C16/06; C23C16/08; C23C16/4401; C23C16/4402; C23C16/4405; C23C16/45561; H; H10; H10D; H10D64/00; H10D64/01; H10D64/011; H10D64/0111; H10D64/0112; H10P; H10P14/00; H10P14/40; H10P14/42; H10P14/43; H10P14/432; H10W; H10W20/00; H10W20/01; H10W20/031; H10W20/032; H10W20/033; H10W20/042; H10W20/045; H10W20/052; H10W20/0526; H10W20/056; H10W20/057; Y; Y10; Y10S; Y10S156/00; Y10S156/916; Y10T; Y10T137/00; Y10T137/7722; Y10T137/7758; Y10T137/7761
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
110 words
A method of forming a barrier layer for electrically connecting a conductive interconnect layer to one or more exposed silicon regions on a wafer comprising the steps of: forming an optically opaque layer of refractory metal on said exposed silicon regions prior to a temperature of said regions exceeding approximately 100°C; heating said wafer in a CVD chamber at a substantially constant deposition temperature while supplying an amount of reducing gas and an amount of refractory metal based gas for a time to form a barrier layer having a desired thickness; and annealing said wafer to form a silicide at an interface of said refractory metal and said silicon regions.
Claim 2
Dependent Claim
73 words
A method as claimed in claim 1 comprising the step of saturating surfaces of the exposed silicon regions at approximately room temperature with refractory metal based gas, before the step of forming an opaque layer, to form a base layer of refractory metal on the surfaces in order to increase bonding strength between the barrier layer and the silicon regions and to act as a catalyst for subsequent deposition of the refractory metal.
Claim 3
Independent Claim
134 words
A method of forming a barrier layer for electrically connecting a conductive interconnect layer to one or more exposed silicon regions on a wafer comprising the steps of: saturating surfaces of the exposed silicon regions at approximately room temperature with refractory metal based gas to form a base layer of refractory metal on the surfaces of the silicon regions in order to increase bonding strength between a subsequently deposited refractory metal layer and said surfaces; heating said wafer in a CVD chamber at a substantially constant deposition temperature while supplying an amount of reducing gas and an amount of refractory metal based gas for a time to form a barrier layer having a desired thickness; and annealing the wafer to form a silicide at an interface of said refractory metal and the silicon regions.
Claim 4
Dependent Claim
71 words
A method as claimed in claim 1, 2 or 3 wherein the step of heating the wafer in a CVD chamber at a substantially constant deposition temperature while supplying an amount of reducing gas includes ramping up the supply of reducing gas with time in order to increase the deposition rate of the refractory metal as exothermic reduction reactions continue to increase the temperature of the barrier layer while being formed.
Claim 5
Dependent Claim
17 words
A method as claimed in claim 4 wherein the silicon regions comprise both N-type and P-type regions.
Claim 6
Independent Claim
115 words
A method of forming a barrier layer for electrically connecting a conductive interconnect layer to one or more exposed silicon regions on a wafer comprising the steps of: heating the wafer in a CVD chamber at a substantially constant deposition temperature while supplying an increasing amount of reducing gas with respect to an amount of refractory metal based gas in order to increase the deposition rate of refractory metal as exothermic reduction reactions continue to increase the temperature of refractory metal deposited over said exposed silicon regions; and annealing the water, after a barrier layer having a desired thickness is formed, to form a silicide at an interface of the refractory metal and silicon regions.
Claim 7
Dependent Claim
111 words
A method as claimed in claim 6 comprising the step of: heating the wafer in a CVD chamber at a substantially constant deposition temperature while supplying an amount of reducing gas, and not supplying an amount of refractory metal base gas, so as to nucleate the reducing gas with the one or more exposed silicon regions and with surfaces of oxide regions separating the one or more exposed silicon regions, this step being conducted in order to blanket deposit a barrier layer and being conducted prior to the step of heating the wafer while supplying an increasing amount of reducing gas with respect to an amount of refractory metal base gas.
Claim 8
Dependent Claim
64 words
A method as claimed in claim 7 comprising the step of: etching a resulting barrier layer formed by the combination of reducing gas and refractory metal base gas in said chamber to a desired thickness, this step being conducted after said step of heating said wafer while supplying an increasing amount of reducing gas with respect to an amount of refractory metal base gas.
Claim 9
Independent Claim
32 words
A method as claimed in any preceding claim wherein the reducing gas is silane (SiH₄) and wherein the annealing step also reacts silicon atoms within the barrier layer to form a silicide.
Claim 10
Independent Claim
30 words
A method as claimed in any preceding claim wherein the annealing step comprises subjecting the wafer to a temperature of above approximately 650°C for a time exceeding approximately 10 seconds.
Claim 11
Independent Claim
24 words
A method as claimed in any preceding claim wherein the wafer is heated by applying power to a lamp for directly radiating the wafer.
Claim 12
Independent Claim
19 words
A method as claimed in any preceding claim wherein the refractory metal is tungsten, molybdenum, palladium, platinum, or tantalum.
Claim 13
Independent Claim
127 words
A method of forming a conductive via in contact with a polysilicon layer for providing electrical contact between the polysilicon layer and a metal layer, the polysilicon layer being formed on a wafer, comprising the steps of: heating the wafer in a CVD chamber at a substantially constant deposition temperature while supplying an increasing amount of reducing gas with respect to an amount of refractory metal based gas in order to increase the deposition rate of refractory metal on the polysilicon layer as exothermic reduction reactions continue to increase the temperature of refractory metal deposited over the polysilicon layer; and annealing the wafer, after a via is formed having a desired thickness, to form a silicide at an interface of the refractory metal and the polysilicon layer.
Claim 14
Dependent Claim
107 words
A method as claimed in claim 13 comprising the step of: heating the wafer in a CVD chamber at a substantially constant deposition temperature while supplying an amount of reducing gas, and not supplying an amount of refractory metal base gas, so as to nucleate said reducing gas with exposed portions of said polysilicon layer and with surfaces of oxide regions formed over said polysilicon layer, this step being conducted in order to blanket deposit a conductive via and being conducted prior to said step of heating said wafer while supplying an increasing amount of reducing gas with respect to an amount of refractory metal base gas.
Claim 15
Dependent Claim
61 words
A method as claimed in claim 14 comprising: etching a resulting conductive via formed by the combination of reducing gas and refractory metal base gas in said chamber to a desired thickness, this step being conducted after said step of heating said wafer while supplying an increasing amount of reducing gas with respect to an amount of refractory metal base gas.
Claim 16
Dependent Claim
17 words
A method as claimed in claim 13, 14 or 15 wherein the reducing gas is silane (SiH₄).
Claim 17
Dependent Claim
51 words
A method as claimed in claim 16 comprising the step of heating the wafer in the CVD chamber while supplying an amount of refractory metal on the polysilicon layer to increase bonding strength between the polysilicon layer and a subsequently formed refractory metal layer deposited using silane as a reducing gas.
Claim 18
Dependent Claim
17 words
A method as claimed in claim 13, 14 or 125 wherein the reducing gas is hydrogen (H₂).
Claim 19
Independent Claim
119 words
A method of forming a conductive via in contact with a first metal layer for providing electrical contact between the first metal layer and a second metal layer, the first metal layer being formed on a wafer, the method comprising the steps of: cleaning an exposed surface of said first metal layer; and heating said wafer in a CVD chamber at a substantially constant deposition temperature while supplying an increasing amount of reducing gas with respect to an amount of refractory metal based gas in order to increase the deposition rate of refractory metal on said first metal layer as exothermic reduction reactions continue to increase the temperature of a refractory metal layer deposited over said first metal layer.
Claim 20
Dependent Claim
27 words
A method as claimed in claim 19 wherein the cleaning step comprising using an RF sputter etch to clean the exposed surface of the first metal layer.
Claim 21
Independent Claim
165 words
A method of forming a conductive via in contact with a first metal layer for providing electrical contact between said first metal layer and a second metal layer, the first metal layer being formed on a wafer, the method comprising the steps of: heating said wafer in a CVD chamber at a substantially constant deposition temperature while supplying an amount of reducing gas, and not an amount of refractory metal base gas, in order to nucleate said reducing gas with exposed portions of said first metal layer and with oxide formed on a surface of said wafer; and heating said wafer in a CVD chamber at a substantially constant deposition temperature while supplying an increasing amount of said reducing gas with respect to an amount of refractory metal base gas in order to increase the deposition rate of refractory metal on said first metal layer as exothermic reduction reactions continue to increase the temperature of a refractory metal layer deposited over said first metal layer.
Claim 22
Dependent Claim
22 words
A method as claimed in claim 19, 20 or 21 wherein the first metal layer and the second metal layer comprise aluminum.
Claim 23
Dependent Claim
18 words
A method as claimed in claim 19, 20, 21 or 22 wherein the reducing gas is silane (SiH₄).
Claim 24
Independent Claim
132 words
An apparatus for forming a barrier layer for electrically contacting a conductive interconnect layer to one or more exposed silicon regions on a wafer, the apparatus comprising: means for forming an optically opaque layer of refractory metal on said exposed silicon regions prior to a temperature of said regions exceeding approximately 100°C; means for heating said wafer in a CVD chamber at a substantially constant deposition temperature while supplying an amount of reducing gas and an amount of refractory metal based gas for a time to form a barrier layer having a desired thickness; means for annealing said wafer to form a silicide at an interface of said refractory metal and said silicon regions; and means for automatically controlling said means for forming, said means for heating, and said means for annealing.
Claim 25
Independent Claim
131 words
An apparatus for forming a barrier layer for electrically contacting a conductive interconnect layer to one or more exposed silicon regions on a wafer, the apparatus comprising: means for heating said wafer in a CVD chamber at a substantially constant deposition temperature while supplying an increasing amount of reducing gas with respect to an amount of refractory metal based gas in order to increase the deposition rate of refractory metal as exothermic reduction reactions continue to increase the temperature of refractory metal deposited over said exposed silicon regions; means for annealing said wafer, after a barrier layer having a desired thickness is formed, to form a silicide at an interface of said refractory metal and silicon regions; and means for automatically controlling said means for heating and said means for annealing.
Claim 26
Independent Claim
169 words
An apparatus for forming a barrier layer for electrically contacting a conductive interconnect layer to one or more exposed silicon regions on a wafer, said apparatus comprising: means for saturating surfaces of said exposed silicon regions at approximately room temperature with refractory metal based gas to form a base layer of refractory metal on said surfaces of said silicon regions in order to increase bonding strength between a subsequently deposited refractory metal layer and said surfaces and to act as a catalyst for subsequent deposition of said refractory metal; means for heating said wafer in a CVD chamber at a substantially constant deposition temperature while supplying an amount of reducing gas in an amount of refractory metal based gas for a time to form a barrier layer having a desired thickness; means for annealing said wafer to form a silicide at an interface of said refractory metal and said silicon regions; and means for automatically controlling said means for saturating, said means for heating, and said means for annealing.
Claim 27
Independent Claim
141 words
An apparatus for forming a conductive via in contact with a polysilicon layer for providing electrical contact between said polysilicon layer and a metal layer, said polysilicon layer being formed on a wafer, said apparatus comprising: means for heating said wafer in a CVD chamber at a substantially constant deposition temperature while supplying an increasing amount of reducing gas and an amount of refractory metal based gas in order to increase the deposition rate of refractory metal on said polysilicon layer as exothermic reduction reactions continue to increase the temperature of refractory metal deposited over said polysilicon layer; means for annealing said wafer, after a via is formed having a desired thickness, to form a silicide at an interface of said refractory metal and said polysilicon layer; and means for automatically controlling said means for heating and said means for annealing.
Claim 28
Independent Claim
131 words
An apparatus for forming a conductive via in contact with a first metal layer for providing electrical contact between said first metal layer and a second metal layer, said first metal layer being formed on a wafer, said apparatus comprising: means for cleaning an exposed surface of said first metal layer; means for heating said wafer in a CVD chamber at a substantially constant deposition temperature while supplying an increasing amount of reducing gas and an amount of refractory metal based gas in order to increase the deposition rate of refractory metal on said first metal layer as exothermic reduction reactions continue to increase the temperature of a refractory metal layer deposited over said first metal layer; and means for automatically controlling said means for cleaning, and said means for heating.
Claim 29
Dependent Claim
62 words
An method as claimed in claim 28 wherein the means for cleaning is an RF sputter etch chamber connected to said CVD chamber by a wafer transport system, said etch chamber, CVD chamber, and wafer transport system being connected such that said wafer can be transported from said etch chamber to said CVD chamber without exposure of said wafer to atmospheric pressure.
Claim 30
Dependent Claim
111 words
A structure for filtering process gases prior to the process gases being allowed to enter a CVD chamber, the structure comprising: input ports (6-8) connected to sources of the process gases; first valve means (12-14) connected immediately downstream from each of the input ports for coupling the input ports to first sections of a gas line; first filter means (60-62) located immediately downstream from the first valve means; second valve means (22,26,40) located downstream from the first filter means for coupling the first sections of the gas line to second sections of the gas line; and second filter means (70-72) connected between the second gas valve means and the CVD chamber.
Claim 31
Dependent Claim
48 words
A structure as claimed in claim 30 comprising an enclosure enclosing the input ports, first valve means, first filter means, second valve means, and the second filter means, and an internal heating element (87) located within the enclosure for baking the structure to vaporize contaminants within said structure.
Claim 32
Dependent Claim
18 words
A structure as claimed in claim 30 or 31 wherein the process gases include tungsten hexafluoride and silane.
Claim 33
Independent Claim
55 words
A method of performing an in-situ etch of a CVD chamber for cleaning the chamber comprising the steps of: heating walls of the chamber to a temperature of above approximately 65°C; injecting an etching gas of NF₃ into the chamber; and supplying RF power to energize the NF₃ to etch the walls of the chamber.
Claim 34
Independent Claim
55 words
An apparatus for performing an in-situ etch of a CVD chamber for cleaning the chamber, the apparatus comprising: means for heating the chamber to a temperature of above approximately 65°C; means for injecting an etching gas of NF₃ into the chamber; and means for automatically controlling the means for heating and the means for injecting.
Claim 35
Independent Claim
44 words
A method of diffusing gas into a CVD chamber, the method comprising diffusing the gas through a diffusing means formed of grains of a material sintered together and formed such that the gas is allowed to escape through spaces between individual grains sintered together.
References Cited (Backward Citations)
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