Method for forming a contact opening in a semiconductor device
A method of forming a self-aligned contact opening in an insulative layer formed over a substrate in a semiconductor device involves etching the insulative layer with at least one fluorocarbon and ammonia.
1. A process for forming an opening in an insulative layer formed over a substrate in a semiconductor device, said process comprising:
forming a pair of adjacent gate stacks over said substrate;
forming sidewall spacers on sidewalls of said adjacent gate stacks;
forming an insulative layer over said substrate;
forming a patterned photoresist mask layer over said insulative layer; and,
etching an opening in said insulative layer defined at least in part by said sidewall spacers through an aperture in said patterned photoresist mask layer, wherein said opening is etched through to said substrate using a combination consisting essentially of ammonia and at least one fluorocarbon, wherein said at least one fluorocarbon is selected from the group consisting of C 4 F 8 , C 4 F 6 , C 5 F 8 , CF 4 , C 2 F 6 , CHF 3 , CH 2 F 2 and C 3 F 8 , and wherein the flow rate ratio of said at least one fluorocarbon to said ammonia is from about 2:1 to about 40:1, and wherein the step of etching an opening in said insulative layer forms a protective layer on said sidewall spacers that is from about 5 to about 50 Å thick.
2. The method of claim 1 , wherein said etching is performed to produce a self-aligned contact opening in said insulative layer, said opening is self-aligned between said adjacent gate stack structures with sidewall spacers.
3. The process of claim 1 , wherein said etching is performed in a reaction chamber.
4. The process of claim 3 , wherein said at least one fluorocarbon and said ammonia are flowed into said reaction chamber such the flow rate ratio of said at least one fluorocarbon to said ammonia is not less than about 3:1.
5. The process of claim 1 , wherein said flow rate ratio is within the range of about 4:1 to about 10:1.
6. The process of claim 1 , wherein said etching is performed without forming an etch stop.
7. The process of claim 6 , wherein said opening is formed between said sidewall spacers on said pair of adjacent gate stacks.
8. The process of claim 7 , wherein said etching is performed at a temperature within the range of about −50 to about 80 degrees Celsius.
9. The process of claim 8 , wherein said etching is performed at a temperature within the range of about 0 to about 80 degrees Celsius.
10. The process of claim 9 , wherein said method further comprises removing said photoresist mask layer after said etching.
11. A method of forming a conductive plug between adjacent gate stacks with sidewall spacers and inside a self-aligned contact opening formed in an insulative layer provided over a substrate in a semiconductor device, said method comprising:
contacting said insulative layer with a plasma etchant mixture consisting essentially of ammonia and at least one fluorocarbon at a temperature within the range of from about −50 to about 80 degrees Celsius so as to form a self-aligned contact opening defined at least in part by said sidewall spacers on adjacent gate stacks in said insulative layer without an etch stop, wherein said contacting further forms a protective layer over opposed sidewall spacers which have been formed over said adjacent gate stacks that is from about 5 to about 50 Å thick, wherein the flow rate ratio of said at least one flurocarbon to said ammonia is from about 2:1 to about 40:1, and said flow rate of said ammonia is at least about 2 sccm; and,
depositing a conductive plug inside said etched opening such that said conductive plug is separated from said sidewall spacers by said protective layer.
12. The method of claim 11 , wherein said contacting is performed by flowing said ammonia over said device in a reaction chamber at a flow rate within the range of about 2 sccm to about 6 sccm.
13. The method of claim 11 , wherein said at least one fluorocarbon is at least one member selected from the group consisting of C 4 F 8 , C 4 F 6 , C 5 F 8 , CF 4 , CHF 3 , and CH 2 F 2 and is flowed over said device at a flow rate within the range of about 10 sccm to about 45 sccm.
14. The method of claim 13 , wherein said mixture comprises at least two fluorocarbons and said flow rate ratio of each said fluorocarbon to said ammonia is within the range of about 3:1 to about 20:1.
15. The method of claim 14 , wherein said mixture comprises three fluorocarbons and said flow rate ratio is within the range of about 4:1 to about 10:1.
16. The method of claim 11 , wherein said protective layer is a nitrogen containing layer.
17. The method of claim 11 , wherein said temperature is a pedestal temperature and said range is from about 0 to about 50 degrees Celsius.