Systems for selective deposition using a sacrificial capping layer
Methods and systems for selectively depositing a p-type doped silicon germanium layer and structures and devices including a p-type doped silicon germanium layer are disclosed. An exemplary method includes providing a substrate, comprising a surface comprising a first area comprising a first material and a second area comprising a second material, within a reaction chamber; depositing a p-type doped silicon germanium layer overlying the surface, the p-type doped silicon germanium layer comprising gallium; and depositing a cap layer overlying the p-type doped silicon germanium layer. The method can further include an etch step to remove the cap layer and the p-type doped silicon germanium layer overlying the second material.
1 . A system comprising:
one or more reaction chambers;
a gas injection system fluidly coupled to at least one of the one or more reaction chambers;
a first gas source;
a second gas source;
a third gas source;
an exhaust source; and
a controller,
wherein the controller is configured to control gas flow into the gas injection system to selectively form a p-type doped silicon germanium layer overlying a first surface of a substrate relative to a second surface of the substrate by performing the steps of:
depositing a p-type doped silicon germanium layer overlying the first surface and the second surface, the p-type doped silicon germanium layer comprising gallium;
depositing a cap layer overlying the p-type doped silicon germanium layer;
selectively etching the cap layer and the p-type doped silicon germanium layer overlying the second surface; and
repeating the steps of depositing the p-type doped silicon germanium layer, depositing the cap layer, and selectively etching the cap layer and the p-type doped silicon germanium layer overlying the second surface to thereby selectively form the p-type doped silicon germanium layer overlying the first surface relative to the second surface.
2 . The system of claim 1 , wherein the controller is configured to perform the step of depositing the cap layer and the step of selectively etching the cap layer and the p-type doped silicon germanium layer overlying the second surface in a same reaction chamber of the one or more reaction chambers.
3 . The system of claim 1 , wherein the first gas source comprises a silicon precursor.
4 . The system of claim 1 , wherein the second gas source comprises a germanium precursor.
5 . The system of claim 1 , wherein the second gas source comprises a p-type dopant precursor and/or a gallium precursor.
6 . The system of claim 1 , further comprising an etchant gas source coupled to the one or more reaction chambers.
7 . The system of claim 6 , wherein the etchant gas source comprises a halide.
8 . The system of claim 7 , wherein the halide comprises one or more of hydrogen chloride and chlorine.
9 . The system of claim 1 ,
wherein the steps of depositing the p-type doped silicon germanium layer, depositing the cap layer and the selective etching are performed in the same reaction chamber; and,
wherein the steps of depositing the p-type doped silicon germanium layer, depositing the cap layer, and the selective etching are repeated 1 to about 500 times.
10 . The system of claim 1 , wherein the p-type doped silicon germanium layer comprises boron.
11 . The system of claim 1 , wherein the step of depositing a p-type doped silicon germanium layer does not include exposing the first surface to a gas comprising a halide.
12 . The system of claim 1 , wherein the steps of depositing the p-type doped silicon germanium layer and depositing the cap layer are performed in the same reaction chamber.
13 . The system of claim 1 , wherein the first gas source comprises a precursor, and wherein the controller monitors a flowrate of the precursor.
14 . The system of claim 1 , wherein the controller controls a temperature within a reaction chamber of the one or more reaction chambers to a temperature between 350° C. to 600° C.
15 . The system of claim 1 , wherein the one or more reaction chambers comprise two or more reaction chambers coupled to the controller.
16 . The system of claim 1 , wherein the gas injection system is configured to meter and control gas flow of a gas from one or more of the first gas source, the second gas source, and the third gas source.
17 . The system of claim 16 , wherein the gas injection system is configured to meter and control gas flow of each gas from the first gas source, the second gas source, and the third gas source.
18 . The system of claim 1 , wherein the cap layer comprises silicon.
19 . The system of claim 1 , wherein the cap layer comprises p-type doped silicon.
20 . The system of claim 1 , wherein the cap layer is removed during the step of selectively etching the cap layer and the p-type doped silicon germanium layer overlying the second surface.