Boron diffusion in silicon devices
Disclosed are various embodiments that include a process, an arrangement, and an apparatus for boron diffusion in a wafer. In one representative embodiment, a process is provided in which a boric oxide solution is applied to a surface of the wafer. Thereafter, the wafer is subjected to a fast heat ramp-up associated with a first heating cycle that results in a release of an amount of boron for diffusion into the wafer.
1. A process for boron diffusion in a wafer, comprising the steps of:
applying a boric oxide solution to a surface of the wafer;
heating the wafer during a first heating cycle at a ramp-up rate greater than 10° C. per second to:
form a borosilicate glass on the surface of the wafer;
release an amount of boron underneath the borosilicate glass; and
heating the wafer during a second heating cycle to;
diffuse the released boron into the wafer;
wherein the first heating cycle and the second heating cycle occur consecutively during a single heating process.
2. The process of claim 1 , further comprising the step of cleaning the surface of the wafer so that the surface is hydrophilic.
3. The process of claim 1 , further comprising the step of cleaning the surface of the wafer so that the surface is hydrophobic.
4. The process of claim 1 , wherein the boric oxide solution further comprises boric acid.
5. The process of claim 1 , wherein the boric oxide solution further comprises the boric oxide in a solvent taken from a group consisting of ethanol and Isopropanol (IPA).
6. The process of claim 3 , wherein the boric oxide solution further comprises a solvent that promotes the uniform coating of the boric oxide solution on the hydrophobic surface.
7. The process of claim 1 , wherein heating the wafer during the first heating cycle further comprises the steps of:
evaporating a solvent component of the boric oxide solution;
minimizing evaporation of the boric oxide; and
facilitating a reaction between the boric oxide and the silicon to release the amount of boron underneath the borosilicate glass.
8. The process of claim 7 , wherein the reaction between the boric oxide and the silicon forms a boron-silicon alloy due to a partial diffusion of the boron into the wafer.
9. The process of claim 8 , wherein the borosilicate glass is removed from the surface of the wafer.
10. The process of claim 1 , further comprising controlling a thickness of the borosilicate glass by adjusting a concentration of an amount of boric oxide in the boric oxide solution applied to the surface of the wafer.
11. The process of claim 1 , wherein the wafer is heated during the first heating cycle at a rate of about 30° C. per second.
12. The process of claim 1 , wherein the first heating cycle comprises an operating temperature that falls within a range of 400° C. to 1000° C.
13. The process of claim 1 , wherein the boric oxide solution is applied to the surface of the wafer by spraying the boric oxide solution onto the surface of the wafer.
14. The process of claim 1 , wherein the boric oxide solution is applied to the surface of the wafer by dipping the wafer into the boric oxide solution.
15. The process of claim 1 , wherein the boric oxide solution is applied to the surface of the wafer by spinning the boric oxide solution onto the wafer.
16. A process for boron diffusion in a silicon wafer, comprising the steps of:
applying a boric oxide solution to a surface of the wafer;
heating the wafer during a first heating cycle at a ramp-up rate greater than 10° C. per second to:
form a borosilicate glass on an outer surface of the wafer;
release boron from the boric oxide into the silicon; and
form a boron-silicon alloy underneath the borosilicate glass;
heating the wafer during a second heating cycle to diffuse boron from the boron-silicon alloy into the wafer; and
wherein the first heating cycle and the second heating cycle occur consecutively during a single heating process.