Method of forming abrupt source drain metal gate transistors
View Patent ↗A gate structure may be utilized as a mask to form source and drain regions. Then the gate structure may be removed to form a gap and spacers may be formed in the gap to define a trench. In the process of forming a trench into the substrate, a portion of the source drain region is removed. Then the substrate is filled back up with an epitaxial material and a new gate structure is formed thereover. As a result, more abrupt source drain junctions may be achieved.
1. A method comprising:
forming a dummy gate with first sidewall spacers;
using said dummy gate with first sidewall spacers as a mask to form a source and drain:
covering said dummy gate with a dielectric;
planarizing the dielectric;
removing the dummy gate, but not said first sidewall spacers, to form a gap in said dielectric;
forming second sidewall spacers in said gap;
etching a substrate through said gap with said second sidewall spacers;
filling the etched substrate with a semiconductor material;
removing said second sidewall spacers; and
forming a gate electrode in said gap.
2. The method of claim 1 including using said spacers to etch a trench into said substrate through said gap.
3. The method of claim 2 including depositing a semiconductor material into said trench to partially fill said trench.
4. The method of claim 3 including filling said trench to a level substantially equal to the level of said substrate.
5. The method of claim 4 including forming a gate dielectric and a gate electrode over said semiconductor material.
6. The method of claim 5 including filling said trench with an epitaxial material.