Methods for forming guard rings on fin structures
A method includes forming a gate stack over a semiconductor fin, wherein the semiconductor fin forms a ring, and etching a portion of the semiconductor fin not covered by the gate stack to form a recess. The method further includes performing an epitaxy to grow an epitaxy semiconductor region from the recess, forming a first contact plug overlying and electrically coupled to the epitaxy semiconductor region, and forming a second contact plug, wherein the second contact plug is overlying and electrically coupled to the gate stack.
1. A method comprising:
forming a gate stack over a semiconductor fin, wherein the semiconductor fin forms a ring;
etching a portion of the semiconductor fin not covered by the gate stack to form a recess;
performing an epitaxy to grow an epitaxy semiconductor region from the recess;
forming a first contact plug overlying and electrically coupled to the epitaxy semiconductor region; and
forming a second contact plug, wherein the second contact plug is overlying and electrically coupled to the gate stack.
2. The method of claim 1 further comprising forming an electrical connection to electrically interconnect the first contact plug and the second contact plug.
3. The method of claim 1 further comprising:
during the forming the gate stack, simultaneously forming a plurality of gate stacks over the semiconductor fin;
during the etching the portion of the semiconductor fin, etching a plurality of portions of the semiconductor fin to form a plurality of recesses between neighboring ones of the plurality of gate stacks;
during the epitaxy, simultaneous growing a plurality of epitaxy semiconductor regions from the plurality of recesses;
forming a plurality of third contact plugs over and electrically coupled to each of the plurality of the epitaxy semiconductor regions; and
forming a plurality of fourth contact plugs over and electrically coupled to the plurality of gate stacks.
4. The method of claim 3 further comprising forming electrical connections to interconnect the plurality of third contact plugs and the plurality of fourth contact plugs.
5. The method of claim 1 further comprising forming a Fin Field-Effect Transistor (FinFET) in a region encircled by the ring.
6. The method of claim 1 , wherein the epitaxy semiconductor region is a p-type region, wherein the method further comprises forming a p-well region, and wherein the epitaxy semiconductor region is located in, and is in contact with, the p-well region.
7. The method of claim 1 , wherein the epitaxy semiconductor region is an n-type region, wherein the method further comprising forming an n-well region, and wherein the epitaxy semiconductor region is located in, and is in contact with, the n-well region.
8. The method of claim 1 further comprising:
doping the epitaxy semiconductor region with a p-type impurity; and
forming an electrical connection to electrically connect the epitaxy semiconductor region to a voltage source, wherein the voltage source is configured to provide a VSS voltage or a negative voltage to the epitaxy semiconductor region.
9. The method of claim 8 further comprising interconnecting the first contact plug and the second contact plug.
10. The method of claim 1 further comprising:
doping the epitaxy semiconductor region with an n-type impurity; and
forming an electrical connection to electrically connect the epitaxy semiconductor region to a voltage source, wherein the voltage source is configured to provide a positive voltage to the epitaxy semiconductor region.