Delta-doping at wafer level for high throughput, high yield fabrication of silicon imaging arrays
Systems and methods for producing high quantum efficiency silicon devices. A silicon MBE has a preparation chamber that provides for cleaning silicon surfaces using an oxygen plasma to remove impurities and a gaseous (dry) NH 3 +NF 3 room temperature oxide removal process that leaves the silicon surface hydrogen terminated. Silicon wafers up to 8 inches in diameter have devices that can be fabricated using the cleaning procedures and MBE processing, including delta doping.
1. A silicon processing method, comprising the steps of:
providing an MBE apparatus, comprising:
an epitaxy chamber configured to perform molecular beam epitaxy on a silicon material;
two preparation chambers, at least one preparation chamber of said two preparation chambers configured to clean a surface of said silicon material of surface contaminants by a process having an impurity removal step, and having an oxide removal step, said at least one preparation chamber having at least one mutual communication port with said epitaxy chamber whereby said silicon material can be transferred between said epitaxy chamber and said at least one preparation chamber; said at least one preparation chamber having in communication therewith a plasma source configured to generate an oxidizing plasma, at least one throttle valve, at least one controller, and at least one reactive gas supply configured to provide reagent gases to said at least one preparation chamber; and pumping equipment configured to provide a reduced pressure within said at least one preparation chamber;
providing a silicon material to be processed;
removing an impurity from a surface of said silicon material;
reacting an oxide present on said surface of said silicon material with reagent gases to form a silicon compound volatile at a temperature below 450° C.; and
removing said silicon compound to provide a clean hydrogen-bonded silicon surface on said silicon material.
2. The silicon processing method of claim 1 , further comprising the step of:
performing molecular beam epitaxy on said silicon material.
3. The silicon processing method of claim 2 , wherein said step of performing molecular beam epitaxy on said silicon material comprises performing delta doping.
4. The silicon processing method of claim 1 , wherein said silicon material is maintained at a temperature less than or equal to 450° C.
5. The silicon processing method of claim 1 , wherein said silicon material comprises a device selected from the group of devices consisting of a CCD device, a CMOS device, an NMOS device, a photodiode, and a silicon solar cell.
6. The silicon processing method of claim 1 , wherein said silicon material comprises a device configured to operate under back-illumination.
7. The silicon processing method of claim 1 , wherein said impurity removal step is performed in a first of said two preparation chambers and an oxide removal step is performed in a second of said two preparation chambers.
8. The silicon processing method of claim 1 , wherein said impurity removal step and oxide removal step are repeated multiple times.
9. The silicon processing method of claim 1 , wherein one of said first and second preparation chambers is a glove box.
10. The silicon processing method of claim 1 , wherein said impurity removal step and said oxide removal step are repeated multiple times.
11. The silicon processing method of claim 1 wherein said impurity removal step is an oxidation step.
12. The silicon processing method of claim 11 , wherein said oxidation step is performed using a gas comprising oxygen.
13. The silicon processing method of claim 11 wherein said impurity comprises carbon.
14. The silicon processing method of claim 1 wherein said impurity removal step is a reduction step.
15. The silicon processing method of claim 14 , wherein said reduction step is performed using a gas selected from the group consisting of H 2 , NH 3 , and mixtures thereof.
16. The silicon processing method of claim 14 , wherein said impurity comprises carbon.
17. The silicon processing method of claim 1 , wherein said oxide removal step is performed using a gas selected from the group consisting of NF 3 , NH 3 , N 2 , H 2 and mixtures thereof.
18. The silicon processing method of claim 1 , wherein said oxide removal step is performed using a fluorine containing gas.
19. The silicon processing method of claim 18 , wherein said fluorine containing gas is selected from the group consisting of HF, NF 3 , and F 2 and mixtures thereof.