Silicon dioxide removing method
View Patent ↗A method for removing silicon dioxide residuals is disclosed. The method includes reacting a portion of a silicon dioxide layer (i.e., oxide) to form a reaction product layer, removing the reaction product layer and annealing in an environment to remove oxide residuals. The method finds application in a variety of semiconductor fabrication processes including, for example, fabrication of a vertical HBT or silicon-to-silicon interface without an oxide interface.
1. A method of forming a vertical bipolar transistor having a single crystal base formed on a substrate, the method comprising the steps of:
a) forming a silicon dioxide layer and a dielectric layer on the single crystal base;
b) forming an emitter window in the dielectric layer over the single crystal base to expose a portion of the silicon dioxide layer;
c) reacting the portion of the silicon dioxide layer to form a reaction product layer;
d) removing the reaction product layer from the emitter window to expose a surface of a portion of the single crystal base;
e) annealing the substrate in an inert atmosphere; and
f) forming a single crystal emitter on the exposed surface of the single crystal base.
2. The method of claim 1 , wherein steps (d)–(f) are performed in an oxygen-free ambient to prevent formation of a native oxide layer.
3. The method of claim 1 , wherein steps (d)–(f) are performed in the same process chamber.
4. The method of claim 1 , wherein the annealing step (e) comprises a temperature from approximately 700° C. to approximately 800° C.
5. The method of claim 1 , wherein the single crystal base includes germanium.
6. The method of claim 1 , wherein the dielectric layer comprises silicon nitride.
7. The method of claim 1 , wherein the reacting step (c) comprises a vapor phase etch.
8. The method of claim 1 , wherein the removing step includes evaporating the reaction product from the surface.
9. The method of claim 1 , wherein the step (e) comprises annealing in a reducing atmosphere.
10. The method of claim 9 , wherein the reducing atmosphere comprises hydrogen.
11. A method of forming an interface between a first single crystal silicon layer and a second single crystal silicon layer, the method comprising the steps of:
a) forming a silicon dioxide layer on the second single crystal silicon layer;
b) reacting at least a portion of the silicon dioxide layer to form a reaction product layer;
c) removing the reaction product layer to expose a surface of the second single crystal silicon layer;
d) annealing in an inert atmosphere; and
e) forming the first single crystal silicon layer on the surface of the second single crystal silicon layer.
12. The method of claim 11 , wherein the inert atmosphere comprises hydrogen.