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Improvements on Double-Side Polishing Technique

IP.com Disclosure Number: IPCOM000047061D
Original Publication Date: 1983-Sep-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Cazcarra, V: AUTHOR [+3]

Abstract

During the double-side polishing operation, on 24" equipment, each carrier is provided with a nest which carries a single 100 mm wafer within it. The carriers rotate between two plates, on each of which a polishing pad is attached. The polishing action is obtained due to the movement of the wafer between the two pads in the presence of a polishing solution or slurry, such as SYTON*. The wafer rotates within its carrier so that the material removed at the periphery of the wafer is greater than that removed at the center. Consequently, the wafer geometry is destroyed by the subsequent polishing cycle. The wafer becomes biconvex, and the flatness may be out of specification if the removal is too great (>20 mm).

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Improvements on Double-Side Polishing Technique

During the double-side polishing operation, on 24" equipment, each carrier is provided with a nest which carries a single 100 mm wafer within it. The carriers rotate between two plates, on each of which a polishing pad is attached. The polishing action is obtained due to the movement of the wafer between the two pads in the presence of a polishing solution or slurry, such as SYTON*. The wafer rotates within its carrier so that the material removed at the periphery of the wafer is greater than that removed at the center. Consequently, the wafer geometry is destroyed by the subsequent polishing cycle. The wafer becomes biconvex, and the flatness may be out of specification if the removal is too great (>20 mm). The proposed improvements aim: 1)to reduce the wafer deformation due to the polishing cycle in order to improve the flatness and be able to increase the removal without any risk, and 2)to improve the productivity of the polishing equipment significantly by allowing 2 wafers per carrier. The reduction in the deformation of the wafer is obtained by placing the nest closer to the border of the carrier and by trimming the periphery of the polishing pads on both sides in order to allow the periphery of the wafer to go outside of the pad area during polishing. The pads are cut off 10 mm from the periphery (see the figure). The increase in productivity is obtained because, inasmuch as the nest is closer to the peripher...