Source and drain structures and manufacturing methods
View Patent ↗A semiconductor structure includes a semiconductor substrate; a first gate dielectric on the semiconductor substrate; a first gate electrode over the first gate dielectric; a first lightly doped source or drain (LDD) region in the semiconductor substrate and adjacent the first gate dielectric, wherein the first LDD region comprises arsenic; and a first deep source/drain region in the semiconductor substrate and adjacent the first gate dielectric. The first deep source/drain region comprises phosphorous, and a first phosphorous junction depth in the first deep source/drain region is greater than about three times a first arsenic junction depth in the first deep source/drain region.
1. A semiconductor structure comprising:
a semiconductor substrate;
a first gate dielectric on the semiconductor substrate;
a first gate electrode over the first gate dielectric;
a first lightly doped source or drain (LDD) region in the semiconductor substrate and adjacent the first gate dielectric, wherein the first LDD region comprises arsenic; and
a first deep source/drain region in the semiconductor substrate and adjacent the first gate dielectric, wherein the first deep source/drain region comprises phosphorous, wherein a first phosphorous junction depth in the first deep source/drain region is greater than about three times a first arsenic junction depth in the first deep source/drain region, and wherein a peak concentration of phosphorous to a peak concentration of arsenic has a ratio of greater than about 5.
2. The semiconductor structure of claim 1 , wherein a ratio of the first phosphorous junction depth to the first arsenic junction depth is between about 3 and about 5.
3. The semiconductor structure of claim 1 , wherein the semiconductor structure is in a memory circuit.
4. The semiconductor structure of claim 1 , wherein the first gate electrode has a length of less than about 60 nm.
5. The semiconductor structure of claim 1 further comprising:
a second gate dielectric on the semiconductor substrate;
a second gate electrode over the second gate dielectric;
a second LDD region in the semiconductor substrate and adjacent the second gate dielectric, wherein the second LDD region comprises arsenic; and
a second deep source/drain region in the semiconductor substrate and adjacent the second gate dielectric, wherein the second deep source/drain region comprises arsenic and phosphorous, and wherein a second arsenic junction depth is substantially comparable to a second phosphorous junction depth.
6. The semiconductor structure of claim 5 , wherein a ratio of the second arsenic junction depth to the second phosphorous junction depth is greater than about 0.5.
7. The semiconductor structure of claim 6 , wherein a peak concentration of arsenic in the second deep source/drain region is less than about 3E20/cm 3 .
8. A semiconductor structure comprising:
a semiconductor substrate;
a gate dielectric on the semiconductor substrate;
a gate electrode over the gate dielectric;
a lightly doped source or drain (LDD) region in the semiconductor substrate and adjacent the gate dielectric, wherein the LDD region comprises arsenic; and
a deep source/drain region in the semiconductor substrate and adjacent the gate dielectric, wherein the deep source/drain region comprises phosphorous, and wherein a peak phosphorous concentration in the deep source/drain region is greater than about five times a peak arsenic concentration in the deep source/drain region.
9. The semiconductor structure of claim 8 , wherein a ratio of a phosphorous junction depth to an arsenic junction depth in the deep source/drain region is greater than about 3.
10. The semiconductor structure of claim 8 , wherein an arsenic junction depth in the deep source/drain region is less than about 30 nm.
11. The semiconductor structure of claim 8 , wherein the semiconductor structure is in a memory circuit.
12. The semiconductor structure of claim 8 , wherein the gate electrode has a length of less than about 60 nm.
13. The semiconductor structure of claim 8 further comprising a suicide region on the deep source/drain region, wherein the silicide region comprises nickel.
14. A semiconductor structure comprising:
a semiconductor substrate comprising a first region and a second region;
a memory metal-oxide-semiconductor (MOS) device in the first region, the memory MOS device comprising:
a first gate dielectric on the semiconductor substrate;
a first gate electrode over the first gate dielectric;
a first lightly doped source or drain (LDD) region in the semiconductor substrate and adjacent the first gate dielectric, wherein the first LDD region comprises arsenic; and
a first deep source/drain region in the semiconductor substrate and adjacent the first gate dielectric, wherein the first deep source/drain region comprises phosphorous, and wherein a phosphorous junction depth in the first deep source/drain region is greater than an arsenic junction depth in the first deep source/drain region; and
a logic MOS device in the second region, the logic MOS device comprising:
a second gate dielectric on the semiconductor substrate;
a second gate electrode over the second gate dielectric;
a second LDD region in the semiconductor substrate and adjacent the second gate dielectric, wherein the second LDD region comprises arsenic; and
a second deep source/drain region in the semiconductor substrate and adjacent the second gate dielectric, wherein the second deep source/drain region comprises arsenic and phosphorous, and wherein an arsenic junction depth in the second deep source/drain region is substantially comparable to a phosphorous junction depth in the second deep source/drain region, and wherein the arsenic junction depth in the second deep source/drain region is greater than about two times the arsenic junction depth in the first deep source/drain region.
15. The semiconductor structure of claim 14 , wherein a peak phosphorous concentration in the first deep source/drain region of the memory MOS device is greater than about three times a peak arsenic concentration in the first deep source/drain region of the memory MOS device.
16. The semiconductor structure of claim 14 , wherein a peak arsenic concentration in the second deep source/drain region of the logic MOS device is greater than about two times a peak arsenic concentration in the first deep source/drain region of the memory MOS device.
17. The semiconductor structure of claim 14 , wherein the phosphorous junction depth in the first deep source/drain region of the memory MOS device is greater than about three times the arsenic junction depth in the first deep source/drain region of the memory MOS device.
18. The semiconductor structure of claim 14 , wherein the arsenic junction depth in the second deep source/drain region of the logic MOS device is greater than about two times the arsenic junction depth in the first deep source/drain region of the memory MOS device.