Contact patterning method with transition etch feedback
A method for forming a contact hole in a semiconductor device and related computer-readable storage medium are provided, the method and program steps of the medium including measuring a percentage of oxygen in an etching chamber, and controlling the percentage of oxygen in the etching chamber to enlarge a temporary inner diameter near a top of the contact hole.
1. A method for forming a contact hole in a semiconductor device, comprising:
measuring a percentage of oxygen in an etching chamber; and
controlling the percentage of oxygen in the etching chamber to enlarge a temporary inner diameter near a top of the contact hole.
2. A method as defined in claim 1 wherein the enlarged temporary inner diameter near the top of the contact hole increases a flow of etchant to a bottom of the contact hole.
3. A method as defined in claim 1 wherein the enlarged temporary inner diameter near the top of the contact hole is less than a developed critical dimension (DCD).
4. A method as defined in claim 1 wherein the enlarged temporary inner diameter near the top of the contact hole is less than a final critical dimension (FCD).
5. A method as defined in claim 1 , further comprising:
determining an optimal flow of etchant to a bottom of the contact hole,
wherein the percentage of oxygen is controlled to optimize the flow of etchant to the bottom of the contact hole.
6. A method as defined in claim 1 , further comprising:
comparing the temporary inner diameter near the top of the contact hole with a developed critical dimension (DCD),
wherein the percentage of oxygen is controlled to increase the dimension near the top of the contact hole without reaching the DCD.
7. A method as defined in claim 1 wherein:
the contact hole is one of a plurality of contact holes; and
the percentage of oxygen is controlled to substantially equalize the temporary inner diameters near the tops of each of the plurality of contact holes, respectively.
8. A method as defined in claim 1 wherein enlarging the top of the contact hole reduces a residue restriction near the top of the contact hole.
9. A method as defined in claim 1 wherein enlarging the top of the contact hole reduces a polymer or polymer-like restriction near the top of the contact hole.
10. A method as defined in claim 1 , further comprising:
comparing a polymer-restricted dimension near the top of the contact hole with a developed critical dimension (DCD),
wherein the percentage of oxygen is controlled to reduce without eliminating the polymer restriction.
11. A method as defined in claim 1 wherein:
the contact hole is one of a plurality of contact holes; and
the percentage of oxygen is controlled to substantially equalize polymer restrictions in each of the plurality of contact holes, respectively.
12. A method as defined in claim 1 wherein controlling the percentage of oxygen takes place in a transition step after a first oxide etch and before a second oxide etch.
13. A method as defined in claim 1 wherein controlling the percentage of oxygen comprises controlling the ratio of carbon-fluoride (C4F6) gas to oxygen (O2) gas.
14. A method as defined in claim 1 , further comprising:
controlling a process time for each of a plurality of flow rates through the enlarging temporary inner diameter near the top of the contact hole,
wherein the oxygen percentage and process time are control variables optimized to obtain a desired final critical dimension (FCD) at the bottom of the contact hole.
15. A method as defined in claim 1 wherein a resulting critical dimension at the top of the contact hole is no greater than a developed critical dimension (DCD) at the top of the contact hole.
16. A method as defined in claim 1 wherein a declination angle between a developed critical dimension (DCD) at the top of the contact hole and a final critical dimension (FCD) at the bottom of the contact hole is no less than 88 degrees.
17. A method as defined in claim 1 wherein a final critical dimension (FCD) at a bottom of the contact hole is large enough to substantially prevent open circuit failures.
18. A method as defined in claim 1 wherein the semiconductor device is a 45 nm device and the final critical dimension (FCD) at a bottom of the contact hole is at least 50 nm.
19. A method as defined in claim 1 , further comprising:
controlling a process time for each of a plurality of flow rates through the enlarging temporary inner diameter near the top of the contact hole,
wherein the oxygen percentage and process time are control variables optimized to obtain a desired final critical dimension (FCD) at the bottom of the contact hole, and
wherein the oxygen percentage and process time control variables are further optimized to obtain a resulting critical dimension at the top of the contact hole.
20. A method as defined in claim 1 wherein a resulting critical dimension at the top of the contact hole is small enough to prevent short circuit failures.
21. A method as defined in claim 1 wherein the semiconductor device is a 45 nm device and a resulting critical dimension at the top of the contact hole is less than 65 nm.