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US 6,638,843 B1Granted
Method for forming a silicide gate stack for use in a self-aligned contact etch
AssigneeMicron Technology, Inc.
InventorMax F. Hineman
Life of this patent
Estimating the term…
Abstract
A method for forming a gate stack having a silicide layer that can subsequently undergo a SAC etch is disclosed. The present method provides a layer of insulating material on top of the silicide layer. The insulating material is sufficient to protect the gate stack, including the silicide layer when the low-resistance gate stack is used in subsequent self-aligned contact etch processes.
Claims34
A method for forming a gate structure for a semiconductor device, comprising:
- forming an opening using a directional etching process in an insulating layer over a semiconductor substrate;
- growing a gate oxide at the bottom of said opening;
- forming a conductive gate comprising polysilicon in said opening on said gate oxide, said conductive gate having a thickness within the range of approximately 500 to 1500 Angstroms;
- forming a silicide layer in said opening on said conductive gate by a salicide method, said silicide layer having a thickness within the range of approximately 200 to 500 Angstroms, said salicide method comprising:
- depositing a refractory metal capable of forming a silicide over said polysilicon gate;
- annealing said refractory metal such that refractory metal in contact with said polysilicon is converted to a conductive silicide;
- and
- selectively etching to remove refractory metal not converted to conductive silicide;
- forming an etch protective cap within said opening over a top surface of said silicide layer, said cap being sufficient to protect said conductive gate and silicide layer from being etched during a self-aligned contact etching process, employing said gate structure;
- subsequently etching away said insulating layer;
- and
- forming an insulating spacer on side walls of said gate structure.
9 more elements
A method for forming features of a semiconductor device, comprising:
- forming a gate stack in an opening of a first insulating layer formed over a semiconductor substrate, said gate stack including an oxide layer grown on said substrate, a conductive layer comprising polysilicon in said opening over said oxide layer, a silicide layer in said opening over said conductive layer formed by a salicide process and a cap layer over said silicide layer, said conductive layer having a thickness within the range of approximately 500 to 1500 Angstroms, said salicide process comprising:
- depositing a refractory metal capable of forming a suicide over said polysilicon gate;
- annealing said refractory metal such that refractory metal in contact with said polysilicon is converted to a conductive silicide;
- and
- selectively etching to remove refractory metal not converted to conductive silicide;
- etching away said first insulating layer to leave said gate stack with an etchant selected from the group consisting of C2F6, CH4, C3F8, C4H10, C2F8, CH2F2, CHF3, C2HF5, and CH3F;
- providing a second insulating layer over said substrate and said gate stack;
- performing a self-aligned contact etch of said second insulating layer using said gate stack to align said etch;
- and
- forming an insulating spacer on side walls of said gate stack.
7 more elements
A method for forming a gate structure for a semiconductor device, comprising:
- forming an insulating layer over a substrate;
- masking said insulating layer to define an etching area on top of said insulating layer;
- etching said insulating layer at said etching area down to a top surface of said substrate to form an opening into said insulating layer;
- growing a gate oxide layer on said substrate at the bottom of said opening;
- depositing a polysilicon layer in said opening over said gate oxide layer;
- etching said polysilicon layer to form a polysilicon gate over said gate oxide layer, said polysilicon gate having a thickness within the range of approximately 500 to 1500 Angstroms;
- depositing a refractory metal over said polysilicon gate;
- converting said refractory metal in contact with said polysilicon gate in said opening to a silicide;
- selectively etching said refractory metal to remove refractory metal not converted to silicide;
- forming an etch protective cap in said opening over a top surface of said silicide layer;
- etching away said insulating layer to leave a gate stack comprising said oxide layer, said polysilicon gate, said silicide layer, and said protective cap;
- and
- forming an insulating spacer on side walls of said gate stack.
10 more elements
Dependencies are inferred from the claim text.