N-channel MOSFETs comprising dual stressors, and methods for forming the same
View Patent ↗The present invention relates to a semiconductor device including at least one n-channel field effect transistor (n-FET). Specifically, the n-FET includes first and second patterned stressor layers that both contain a carbon-substituted and tensilely stressed single crystal semiconductor. The first patterned stressor layer has a first carbon concentration and is located in source and drain (S/D) extension regions of the n-FET at a first depth. The second patterned stressor layer has a second, higher carbon concentration and is located in S/D regions of the n-FET at a second, deeper depth. Such an n-FET with the first and second patterned stressor layers of different carbon concentration and different depths provide improved stress profile for enhancing electron mobility in the channel region of the n-FET.
1. A semiconductor device comprising at least one n-channel field effect transistor (n-FET), said at least one n-FET comprising first and second patterned stressor layers that both comprise a carbon-substituted and tensilely stressed single crystal semiconductor, wherein the first patterned stressor layer has a first substitutional carbon concentration and is located in source and drain (S/D) extension regions of the n-FET, wherein the second patterned stressor layer has a second, higher substitutional carbon concentration and is located in S/D regions of the n-FET.
2. The semiconductor device of claim 1 , wherein the first substitutional carbon concentration ranges from about 0.2 atomic % to about 2.5 atomic %, and wherein the second, higher substitutional carbon concentration ranges from about 0.5 atomic % to about 4 atomic %.
3. The semiconductor device of claim 1 , wherein the first substitutional carbon concentration ranges from about 0.5 atomic % to about 2 atomic %, and wherein the second, higher substitutional carbon concentration ranges from about 0.8 atomic % to about 3 atomic %.
4. The semiconductor device of claim 1 , wherein the first patterned stressor layer is located in the S/D extension regions of the n-FET at a first depth ranging from about 5 nm to about 80 nm, and wherein the second patterned stressor layer is located in the S/D regions of the n-FET at a second depth ranging from about 10 nm to about 150 nm.
5. The semiconductor device of claim 4 , wherein the first depth ranges from about 10 nm to about 50 nm, and wherein the second depth ranges from about 20 nm to about 80 nm.
6. The semiconductor device of claim 1 , wherein the first and second patterned stressor layers comprise carbon-substituted and tensilely stressed single crystal silicon.
7. The semiconductor device of claim 1 , wherein the source and drain regions of the at least one n-FET comprise source and drain silicide layers that are located over the second patterned stressor layer and optionally at least a portion of the first patterned stressor layer.