Process for producing a semiconductor wafer
View Patent ↗The invention relates to a process for producing a semiconductor wafer by simultaneous polishing of a front surface and a back surface of the semiconductor wafer with a polishing fluid between rotating polishing plates during a polishing run which lasts for a polishing time, the semiconductor wafer being located in a cutout in a carrier having a defined carrier thickness and being held on a defined geometric path, the semiconductor wafer having a starting thickness prior to polishing and a final thickness after polishing. The polishing time for the polishing run is calculated from data which include the starting thickness of the semiconductor wafer and the carrier thickness as well as the starting thickness and final thickness and the flatness of a semiconductor wafer which was polished during a polishing run preceding the present polishing run.
1. A process for producing a semiconductor wafer by simultaneous polishing of a front surface and a back surface of the semiconductor wafer with a polishing fluid between rotating polishing plates during a polishing run which lasts for a polishing time, the semiconductor wafer being located in a cutout in a carrier having a defined carrier thickness and being maintained on a defined geometric path, the semiconductor wafer having a starting thickness prior to polishing and a final thickness after polishing, wherein the polishing time for the polishing run is calculated from data which include the starting thickness of the semiconductor wafer and the carrier thickness as well as the starting thickness and final thickness and the flatness of a semiconductor wafer which was polished during a polishing run preceding the present polishing run.
2. The process of claim 1 , wherein said preceding polishing run is the run just prior to the present polishing run.
3. The process as claimed in claim 1 , wherein the flatness is incorporated in the calculation in the form of the dnl35 value.
4. The process of claim 3 , wherein polishing time is reduced proportional to the absolute magnitude of a positive dnl35 value.
5. The process of claim 4 , wherein the reduction in polishing time takes place in increments.
6. The process of claim 3 , wherein polishing time is increased proportional to the absolute magnitude of a negative dnl35 value.
7. The process of claim 6 , wherein the increase in polishing time takes place in increments.