Methods for processing semiconductor wafers having a polycrystalline finish
A method of processing a semiconductor wafer includes depositing a silicon layer on the semiconductor wafer. A first slurry is applied to the semiconductor wafer and the silicon layer is polished to smooth the silicon layer. A second slurry is applied to the semiconductor wafer. The second slurry includes a greater amount of a caustic agent than the first slurry.
1. A method of processing a semiconductor wafer comprising:
depositing a silicon layer on the semiconductor wafer;
applying a first slurry to the semiconductor wafer, the first slurry having a pH less than 10 and being free of caustic agent;
polishing the silicon layer to smooth the silicon layer; and
applying a second slurry to the semiconductor wafer, the second slurry comprising caustic agent, the second slurry having a pH between 10 and 12.
2. The method of claim 1 wherein the silicon layer is a polycrystalline silicon layer, the layer having a reduced roughness after polishing and the polycrystalline grain boundary being reduced by polishing.
3. The method of claim 1 wherein the silicon layer is polished using the first slurry for a predetermined time, the predetermined time being in the range between about 1 minute and about 5 minutes.
4. The method of claim 1 wherein predetermined time is approximately 2 minutes.
5. The method of claim 1 wherein the silicon layer is polished using the second slurry for a predetermined time, the predetermined time being in the range between about 5 minutes and about 15 minutes.
6. The method of claim 1 wherein the caustic agent is potassium hydroxide.
7. The method of claim 1 further comprising cleaning the semiconductor wafer to facilitate growth on the silicon layer prior to polishing the silicon layer.
8. The method of claim 7 further comprising forming a silicon oxide layer on the silicon layer prior to polishing the silicon layer.
9. The method of claim 8 wherein cleaning the semiconductor wafer comprises cleaning the semiconductor wafer using a standard clean 1 (SC1).
10. The method as set forth in claim 1 wherein the semiconductor wafer is positioned on a polishing pad while applying the first slurry to the semiconductor wafer, the semiconductor wafer and polishing pad both rotating while applying the first slurry to the semiconductor wafer.
11. The method as set forth in claim 10 wherein the semiconductor wafer is positioned on a polishing pad while applying the second slurry to the semiconductor wafer, the semiconductor wafer and polishing pad both rotating while applying the second slurry to the semiconductor wafer.
12. The method as set forth in claim 11 wherein the polishing pad that rotates while applying the first slurry is different that the polishing pad that rotates while applying the second slurry.