Methods of forming structures including silicon germanium and silicon layers, devices formed using the methods, and systems for performing the methods
Methods and systems for forming structures including one or more layers comprising silicon germanium and one or more layers comprising silicon are disclosed. Exemplary methods can include using a surfactant, using particular precursors, and/or using a transition step to improve an interface between adjacent layers comprising silicon germanium and comprising silicon.
1. A method of forming a structure, the method comprising the steps of:
providing a substrate within a reaction chamber;
forming a first layer comprising silicon and germanium overlying a surface of the substrate; and
forming a second layer comprising silicon overlying the first layer,
wherein the step of forming the first layer comprises providing a surfactant precursor to the reaction chamber only during the last twenty-five percent of the step of forming the first layer, and
wherein the second layer consists essentially of silicon and is in direct contact with the first layer.
2. The method of claim 1 , wherein the surfactant precursor comprises one or more of gallium, tellurium, antimony, indium, tin, and aluminum.
3. The method of claim 1 , wherein the surfactant precursor comprises a halogen.
4. The method of claim 3 , wherein the surfactant precursor comprises a chloride, bromide, or iodine.
5. The method of claim 1 , wherein the surfactant precursor is selected from one or more of the group consisting of GaCl 3 , SnCl 4 , SbCl 3 , AlCl 3 , and InCl 3 .
6. The method of claim 1 , wherein an etchant is provided during the step of forming the first layer.
7. The method of claim 1 , wherein the step of forming the first layer comprises flowing two or more silicon precursors.