Semiconductor device and method of manufacturing the same
A method of manufacturing a semiconductor device is provided. The method includes forming alternating layers, where a silicon germanium layer and a silicon layer are alternately stacked, on a substrate, etching the alternating layers to form a fin structure protruding onto the substrate and then forming a silicon nitride film on a surface and a sidewall of each of the alternating layers having the fin structure, sequentially forming a dummy gate and a silicon oxide film on the alternating layers with the silicon nitride film therebetween and then forming a gate spacer on a sidewall of the dummy gate, etching the silicon nitride film upward exposed, and then, etching the alternating layers by using the silicon oxide film, and selectively forming an inner spacer in a sidewall of each of silicon germanium layers among the silicon germanium layers and silicon layers of the etched alternating layers.
1 . A method of manufacturing a semiconductor device, the method comprising:
forming alternating layers, where a silicon germanium layer and a silicon layer are alternately stacked, on a substrate;
patterning and etching the alternating layers to form a fin structure protruding onto the substrate, and then, forming a silicon nitride film on a surface and a sidewall of each of the alternating layers having the fin structure;
sequentially forming a dummy gate and a silicon oxide film on the alternating layers with the silicon nitride film therebetween, and then, forming a gate spacer on a sidewall of the dummy gate;
etching the silicon nitride film upward exposed, and then, etching the alternating layers by using the silicon oxide film as a hard mask; and
selectively forming an inner spacer in a sidewall of each of silicon germanium layers among the silicon germanium layers and silicon layers of the etched alternating layers by etching a silicon oxide film formed on sidewalls of the silicon germanium layers and the silicon layers until the sidewalls of the silicon layers are exposed,
wherein, when etching the silicon oxide film, the silicon nitride film is hardly etched based on an etching selectivity between the silicon nitride film and the silicon oxide film, such that both end portions of the un-etched silicon nitride film protrude with respect to the sidewalls of each of the silicon layers.
2 . The method of claim 1 , wherein the forming of the alternating layers comprises:
sequentially growing the silicon germanium layer and the silicon layer at a first temperature by using an epitaxial growth process;
cooling the silicon germanium layer and the silicon layer at a second temperature which is lower than the first temperature;
sequentially growing another silicon germanium layer and another silicon layer on the silicon layer at the first temperature by using the epitaxial growth process; and
cooling the other silicon germanium layer and the other silicon layer at the second temperature by using the cooling process.
3 . The method of claim 2 , wherein the first temperature is about 500° C. to about 800° C., and the second temperature is about 300° C. to about 400° C.
4 . The method of claim 1 , wherein the silicon nitride film has a function of preventing short circuit between a gate electrode and a source/drain in a post process.
5 . The method of claim 1 , wherein the forming of the gate spacer comprises forming a gate spacer in the sidewall of the dummy gate by using a thermal oxidation process.
6 . The method of claim 1 , wherein the forming of the inner spacer comprises:
forming the silicon oxide film on the sidewall of each of the silicon germanium layers and the silicon layers of the etched alternating layers; and
forming, as the inner spacer, the silicon oxide film remaining on the sidewalls of the silicon germanium layers in a state where the sidewalls of the silicon layers are exposed.
7 . The method of claim 6 , wherein the forming of the silicon oxide film comprises growing the silicon oxide film on the sidewall of each of the silicon germanium layers and the silicon layers by using a thermal oxidation process.
8 . The method of claim 6 , wherein the forming of the silicon oxide film comprises growing the silicon oxide film on the sidewall of each of the silicon germanium layers and the silicon layers by using a wet oxidation process.
9 . The method of claim 8 , wherein the silicon oxide film formed on the sidewall of each of the silicon germanium layers is grown to have a first width in a center direction of the silicon germanium layers, and the silicon oxide film formed on the sidewall of each of the silicon layers is grown to have a second width in a center direction of the silicon layers.
10 . The method of claim 8 , wherein the wet oxidation process is performed at a temperature of about 700° C. to about 800° C.
11 . The method of claim 1 , wherein the etching of the silicon oxide film comprises etching the silicon oxide film by using a wet etching process.
12 . The method of claim 1 , wherein the protruding both end portions of the silicon nitride film are used as an insulator which prevents short circuit between a gate electrode and a source/drain formed in a post process.
13 . The method of claim 1 , wherein, in the forming of the inner spacer, the inner spacer functions as a structure which supports a space between the silicon layers formed by a post process of removing the silicon germanium layers used as a sacrificial layer.
14 . The method of claim 1 , wherein, in the forming of the inner spacer, the inner spacer functions as a structure which determines a channel length based on silicon layers which are the silicon layers included in the alternating layers and are used as a channel layer.
15 . The method of claim 1 , further comprising:
after the selectively forming of the inner spacer,
forming a source/drain by using the silicon layers and the substrate as a seed layer;
forming a silicon oxide film covering the source/drain and the dummy gate;
polishing the silicon oxide film to expose a surface of the dummy gate;
removing the exposed dummy gate;
removing the silicon nitride film exposed by the removal of the dummy gate;
selectively removing the silicon germanium layers formed between the silicon layers;
forming a gate dielectric layer on a surface of the silicon oxide film, on a sidewall of the silicon oxide film exposed by the removal of the dummy gate, and on all surfaces of each of the silicon layers exposed by the removal of the silicon germanium layers; and
forming the gate electrode on the gate dielectric layer.
16 . The method of claim 15 , wherein, in the etching and removing of the silicon nitride film, both end portions of the silicon nitride film protruding to an inner portion of the silicon oxide film are not removed by the silicon oxide film.
17 . The method of claim 16 , wherein the both end portions of the silicon nitride film maintain an interval between the gate electrode and the source/drain.
18 . The method of claim 16 , wherein the both end portions of the silicon nitride film function as an insulator which prevents short circuit between the gate electrode and the source/drain.