Paired pivot arm
The present invention relates to an apparatus and method for polishing semiconductor substrates. In one embodiment, two polishing heads are mounted on two independent pivoting arms that share one pivot point. Each of the pivoting arms enable the corresponding polishing head direct access to two polishing stations. The polishing system of the present invention provides flexibility and improves throughput.
1. A method for polishing semiconductor substrates, comprising:
providing a first load cup;
providing a first polishing station configured to perform a first polishing step;
providing a second polishing station configured to perform a second polishing step;
providing first and second pivot arms independently pivotable about a first pivot point and configured to carry substrates among the first load cup and the first and second polishing stations;
providing a second load cup;
providing a third polishing station configured to perform the second polishing step;
providing a fourth polishing station configured to perform a third polishing step;
providing third and fourth pivot arms independently pivotable about a second pivot point and configured to carry substrates among the second load cup, the third and fourth polishing stations;
performing the first polishing step to a first substrate by pivoting the first pivot arm over the first polishing station;
performing the second polishing step to the first substrate by pivoting the first pivot arm over the second polishing station while performing the first polishing step to a second substrate by pivoting the second pivot arm over the first polishing station;
transferring the second substrate to the third pivot arm; and
performing the second polishing step to the second substrate by pivoting the third pivot arm over the third polishing station.
2. The method of claim 1 , further comprising:
transferring the first substrate to the fourth pivot arm; and
performing the third polishing step to the first substrate by pivoting the fourth pivot arm over the fourth polishing station; and
performing the third polishing step to the second substrate by pivoting the third pivot arm over the fourth polishing station.
3. The method of claim 1 , wherein transferring the second substrate to the third pivot arm comprises:
disposing the second substrate on the first load cup by pivoting the second pivot arm over the first load cup;
moving the second substrate from the first load cup to the second load cup using a robot; and
mounting the second substrate on the third pivot arm by pivoting the third pivot arm over the second load cup.
4. The method of claim 1 , wherein performing the first polishing step to the first substrate comprises:
retaining the first substrate on a first carrier head mounted on the first pivot arm;
rotating the first carrier head; and
oscillating the first carrier head, and performing the first polishing step to the second substrate comprises:
retaining the second substrate on a second carrier head mounted on the second pivot arm;
rotating the second carrier head; and oscillating the second carrier head.
5. The method of claim 4 , wherein oscillating the first carrier head comprises pivoting the first pivot arm back and forth over the first polishing station, and oscillating the second carrier head comprises pivoting the second pivot arm back and forth over the first polishing station.