Chemical-mechanical polishing apparatus and method
First Claim
1. A CMP method comprising steps of:
- fixing a semiconductor wafer on a wafer carrier having a retainer ring for guiding circumferential edges of the semiconductor wafer;
polishing the semiconductor wafer on a CMP apparatus having a polishing head and a polishing pad covered with slurry; and
after the polishing process is completed, moving the polishing head upward so that the semiconductor wafer is separated from the polishing pad, while reducing the adsorptive force between the semiconductor wafer and the polishing pad by injecting air between the semiconductor wafer and the polishing pad through an opening in the retainer ring.
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Abstract
A chemical-mechanical polishing (CMP) apparatus has a polishing head onto which a semiconductor wafer is fixed for holding the surface of the semiconductor wafer in contact with the surface of a polishing pad. The polishing head includes a wafer carrier and a retainer ring which guides the edges of the semiconductor wafer. The retainer ring has an opening through which air is supplied to the lower portion thereof, such that air is injected between the semiconductor wafer and the polishing pad through the opening before separating the semiconductor wafer from the polishing pad after the polishing process. The injected air reduces the adsorptive force between the semiconductor wafer and the polishing pad. Therefore, the semiconductor wafer can be easily separated from the polishing pad when the polishing head is raised.
30 Citations
7 Claims
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1. A CMP method comprising steps of:
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fixing a semiconductor wafer on a wafer carrier having a retainer ring for guiding circumferential edges of the semiconductor wafer;
polishing the semiconductor wafer on a CMP apparatus having a polishing head and a polishing pad covered with slurry; and
after the polishing process is completed, moving the polishing head upward so that the semiconductor wafer is separated from the polishing pad, while reducing the adsorptive force between the semiconductor wafer and the polishing pad by injecting air between the semiconductor wafer and the polishing pad through an opening in the retainer ring. - View Dependent Claims (2)
sensing whether or not the semiconductor wafer is adhered to the polishing head after the polishing head is separated from the polishing pad; and
displaying a sensing result to a user.
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3. A chemical mechanical polishing (CMP) apparatus comprising:
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a polishing pad having an upper surface onto which a slurry is to be supplied;
a polishing head disposed above said polishing pad, said polishing head including a wafer carrier for holding a wafer and pressing the wafer against the polishing pad, and an annular retainer ring mounted to the bottom of the wafer carrier for guiding the circumferential edge of a wafer as the wafer is being polished, said annular retainer ring having an air injection opening extending therethrough that is open to a lower surface of the ring adjacent the bottom of said wafer carrier; and
an external air injection unit in direct open communication with said air injection opening of the annular retainer ring such that said external air injection unit supplies air into the air injection opening of said retainer ring wherein the air issuing from said air injection opening at said lower surface thereof can be injected between a wafer pressed against the polishing pad by the wafer carrier to thereby separate the wafer from the pad after the wafer has been polished. - View Dependent Claims (4, 5, 6, 7)
said annular retainer ring extends around said elastic membrane, and said external air injection unit is also connected to said air chamber such that said external air injection unit exhausts air from said air chamber to cause a wafer to adhere to said elastic membrane whereby the wafer carrier can transfer a semiconductor wafer onto the polishing pad. -
6. The CMP apparatus according to claim 5, and further comprising a rotary shaft to which said wafer carrier is fixed so as to rotate therewith, said rotary shaft having air lines extending therethrough, and said external air injection unit being connected to both said air chamber and to said air injection opening of the annular retainer ring via said air lines.
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7. The CMP apparatus according to claim 6, and further comprising a manifold connecting said wafer carrier to said rotary shaft, said manifold having connection air lines extending therethrough, said connection lines connecting the air chamber and the air injection opening of said annular retainer ring to said air lines in the rotary shaft.
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Specification