Method and apparatus for aligning and setting the axis of rotation of spindles of a multi-body system
A method and apparatus is disclosed for polishing a semiconductor wafer. A polishing pad including a first surface and a semiconductor wafer including a second surface are aligned to each other. To allow alignment of an axis of rotation of the surfaces, at least one of the first and second surfaces includes an adjustable axis of rotation. After the axis of rotation of the first and second surfaces is aligned, the adjustable axis of rotation is set, preferably with a magneto-rheological fluid or similarly acting material, to maintain a fixed position. Thereafter, the polishing pad is utilized to polish the semiconductor wafer.
1. An apparatus for polishing a semiconductor wafer, comprising:
a polishing pad including a first surface;
a semiconductor wafer including a second surface opposing the first surface of the polishing pad, wherein at least one of an axis of rotation of the first surface and the second surface is adjustable;
a fluid around the axis of rotation of the adjustable surface operable to maintain a position of the axis of rotation after the axis of rotation of the first and second surfaces are aligned, wherein the semiconductor wafer is polished with the polishing pad after the axis of rotation are aligned, wherein the fluid comprises a magneto-rheological fluid; and
a seal to maintain the fluid around the axis of rotation.
2. The apparatus according to claim 1 wherein a magnetic field is applied proximate to the magneto-rheological fluid to set or solidify the magneto-rheological fluid.
3. The apparatus according to claim 2 further including an electrical coil located proximate to the magneto-rheological fluid, wherein application of the magnetic field comprises energizing the electric coil.
4. The apparatus according to claim 2 wherein the magneto-rheological fluid becomes solid after the magnetic field is applied.
5. The apparatus according to claim 2 wherein the magneto-rheological fluid becomes highly viscous after the magnetic field is applied.
6. The apparatus according to claim 2 wherein the magnetic field is alternately applied and disengaged to continually adjust and set the axis of rotation of the first surface to the second surface.
7. The apparatus according to claim 1 further including a first spindle shaft attached with the polishing pad and a second spindle shaft attached with the semiconductor wafer to spin the polishing pad and semiconductor wafer.
8. The apparatus according to claim 7 wherein at least one of the first spindle shaft and the second spindle shaft are enclosed within the fluid.
9. The apparatus according to claim 7 further including at least one fin attached with at least one of the first spindle shaft and the second spindle shaft wherein the at least one fin is surrounded by the fluid.