Transistor protection layers and methods of forming the same
Various embodiments include protection layers for a transistor and methods of forming the same. In an embodiment, a method includes: exposing a semiconductor nanostructure, a dummy nanostructure, and an isolation region by removing a dummy gate; increasing a deposition selectivity between a top surface of the semiconductor nanostructure and a top surface of the isolation region relative a selective deposition process; depositing a protection layer on the top surface of the isolation region by performing the selective deposition process; removing the dummy nanostructure by selectively etching a dummy material of the dummy nanostructure at a faster rate than a protection material of the protection layer; and forming a gate structure around the semiconductor nanostructure.
1 . A method comprising:
exposing a semiconductor nanostructure, a dummy nanostructure, and an isolation region by removing a dummy gate;
increasing a deposition selectivity between a top surface of the semiconductor nanostructure and a top surface of the isolation region relative a selective deposition process;
depositing a protection layer on the top surface of the isolation region by performing the selective deposition process;
removing the dummy nanostructure by selectively etching a dummy material of the dummy nanostructure at a faster rate than a protection material of the protection layer; and
forming a gate structure around the semiconductor nanostructure.
2 . The method of claim 1 , wherein hydroxyl groups dangle from the top surface of the semiconductor nanostructure and from the top surface of the isolation region, and increasing the deposition selectivity between the top surface of the semiconductor nanostructure and the top surface of the isolation region comprises:
replacing the hydroxyl groups dangling from the top surface of the semiconductor nanostructure with amino groups.
3 . The method of claim 2 , wherein replacing the hydroxyl groups comprises:
soaking the semiconductor nanostructure in a nitrogen-containing gas without generating a plasma.
4 . The method of claim 2 , wherein replacing the hydroxyl groups comprises:
bombarding the semiconductor nanostructure with nitrogen-containing ions.
5 . The method of claim 1 , wherein increasing the deposition selectivity between the top surface of the semiconductor nanostructure and the top surface of the isolation region comprises:
depositing an inhibition layer on the top surface of the semiconductor nanostructure.
6 . The method of claim 1 , wherein hydroxyl groups dangle from the top surface of the isolation region, and depositing the protection layer comprises:
soaking the isolation region in a silicon-carbon precursor that adsorbs on oxygen atoms of the hydroxyl groups.
7 . The method of claim 1 , wherein the dummy nanostructure is formed of silicon-germanium, the semiconductor nanostructure is formed of silicon, the protection layer is formed of silicon oxycarbonitride, and removing the dummy nanostructure comprises etching the dummy nanostructure with tetramethylammonium hydroxide or ammonium hydroxide.
8 . The method of claim 1 , wherein the dummy nanostructure is formed of silicon oxide, the semiconductor nanostructure is formed of silicon, the protection layer is formed of silicon oxycarbonitride, and removing the dummy nanostructure comprises etching the dummy nanostructure with dilute hydrofluoric acid.
9 . A method comprising:
exposing a semiconductor nanostructure and an isolation region by removing a dummy gate, wherein hydroxyl groups dangle from a top surface of the semiconductor nanostructure and from a top surface of the isolation region;
performing a treatment process to selectively replace some of the hydroxyl groups with amino groups that dangle from the top surface of the semiconductor nanostructure;
depositing a protection layer on the top surface of the isolation region using a silicon-carbon precursor that reacts with the hydroxyl groups and does not react with the amino groups, the top surface of the semiconductor nanostructure being substantially free from carbon after the protection layer is deposited; and
removing the amino groups that dangle from the top surface of the semiconductor nanostructure.
10 . The method of claim 9 , wherein the treatment process comprises:
soaking the semiconductor nanostructure in ammonia or nitrogen gas without generating a plasma.
11 . The method of claim 9 , wherein the treatment process comprises:
bombarding the semiconductor nanostructure with nitrenium ions or nitrogen ions.
12 . The method of claim 9 , wherein the top surface of the isolation region is substantially free from amino groups after the treatment process.
13 . The method of claim 9 , wherein amino groups dangle from the top surface of the isolation region after the treatment process.
14 . The method of claim 9 , wherein the silicon-carbon precursor is bis(tertiary-butyl-amino)silane or bis(diethylamino) silane.
15 . A method comprising:
exposing a semiconductor nanostructure, a dummy nanostructure, and an isolation region by removing a dummy gate, wherein hydroxyl groups dangle from a top surface of the semiconductor nanostructure and from a top surface of the isolation region;
increasing a deposition selectivity between the top surface of the semiconductor nanostructure and the top surface of the isolation region relative a selective deposition process, wherein increasing the deposition selectivity comprises performing a treatment process to selectively replace some of the hydroxyl groups with amino groups that dangle from the top surface of the semiconductor nanostructure;
depositing a protection layer on the top surface of the isolation region by performing the selective deposition process, wherein the selective deposition process comprises using a silicon-carbon precursor that reacts with the hydroxyl groups and does not react with the amino groups, the top surface of the semiconductor nanostructure being substantially free from carbon after the protection layer is deposited;
removing the dummy nanostructure by selectively etching a dummy material of the dummy nanostructure at a faster rate than a protection material of the protection layer;
removing the amino groups that dangle from the top surface of the semiconductor nanostructure; and
forming a gate structure around the semiconductor nanostructure.
16 . The method of claim 15 , wherein the treatment process comprises soaking the semiconductor nanostructure in ammonia or nitrogen gas without generating a plasma, and wherein the soaking is performed at a temperature in a range of 400° C. to 800° C. and for a duration in a range of 4 hours to 8 hours.
17 . The method of claim 15 , wherein the treatment process comprises bombarding the semiconductor nanostructure with nitrenium ions or nitrogen ions, and wherein the bombarding is performed using a plasma generation power having a high power in a range of 200 watts to 800 watts.
18 . The method of claim 15 , wherein the amino groups are removed by a same etching process as that used to remove the dummy nanostructure.
19 . The method of claim 15 , wherein the amino groups are removed by a separate etching process that is performed after removing the dummy nanostructure.
20 . The method of claim 15 , wherein the hydroxyl groups are formed on the top surface of the semiconductor nanostructure and on the top surface of the isolation region by a surface hydroxylation process performed after removing the dummy gate, and wherein the surface hydroxylation process is a plasma treatment performed with oxygen and hydrogen.