Method of making buried contact module with multiple poly si layers
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorMong-Song Liang
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Abstract
A new method of forming source/drain buried contact junctions is described. The method of forming a buried contact to a source/drain junction or other active device region in a silicon substrate is described. A first polysilicon layer is deposited over the surface of a silicon substrate. A second layer of polysilicon is deposited over the first layer of polysilicon wherein the polysilicon grain boundaries of the first and second polysilicon layers will be mismatched. The second polysilicon layer is doped. The grain boundary mismatch will slow the diffusion of the dopant into the silicon substrate. The dopant is driven in to form the buried contact with a shallow junction.
Claims31
The method of forming a buried contact with a shallow junction in a silicon substrate comprising:
- depositing a first polysilicon layer over the surface of said silicon substrate;
- cooling said silicon substrate after said deposition of said first polysilicon layer to a temperature lower than the deposition temperature;
- depositing a second layer of polysilicon on said first layer of polysilicon after said silicon substrate has been cooled wherein the polysilicon grain boundaries of said first and second polysilicon layers will be mismatched;
- doping said second polysilicon layer wherein the said grain boundary mismatch will slow the diffusion of the dopant into said silicon substrate;
- and
- driving in said dopant to form said buried contact with a shallow junction.
The method of forming a buried contact with a shallow junction in the formation of a static random access memory (SRAM) integrated circuit comprising:
- depositing a first polysilicon layer over the surface of a silicon substrate;
- cooling said silicon substrate after said deposition of said first polysilicon layer to a temperature lower than the deposition temperature;
- depositing a second layer of polysilicon on said first layer of polysilicon after said silicon substrate has been cooled wherein the polysilicon grain boundaries of said first and second polysilicon layers will be mismatched;
- doping said second polysilicon layer wherein the said grain boundary mismatch will slow the diffusion of the dopant into said silicon substrate;
- and
- driving in said dopant to form said buried contact with a shallow junction in the formation of said SRAM integrated circuit.
The method of forming a buried contact with a shallow junction in the formation of a dynamic random access memory (DRAM) integrated circuit comprising:
- depositing a first polysilicon layer over the surface of a silicon substrate;
- cooling said silicon substrate after said deposition of said first polysilicon layer to a temperature lower than the deposition temperature;
- depositing a second layer of polysilicon on said first layer of polysilicon after said silicon substrate has been cooled wherein the polysilicon grain boundaries of said first and second polysilicon layers will be mismatched;
- doping said second polysilicon layer wherein the said grain boundary mismatch will slow the diffusion of the dopant into said silicon substrate;
- and
- driving in said dopant to form said buried contact with a shallow junction in the formation of said DRAM integrated circuit.
The method of forming a buried contact with a shallow junction in a silicon substrate comprising:
- depositing a first polysilicon layer over the surface of said silicon substrate;
- dipping said silicon substrate in dilute hydrofluoric acid after said deposition of said first polysilicon layer;
- depositing a second layer of polysilicon on said first layer of polysilicon after said silicon substrate has been dipped in said hydrofluoric acid wherein the polysilicon grain boundaries of said first and second polysilicon layers will be mismatched;
- doping said second polysilicon layer wherein the said grain boundary mismatch will slow the diffusion of the dopant into said silicon substrate;
- and
- driving in said dopant to form said buried contact with a shallow junction.
Dependencies are inferred from the claim text.