Tech Semiconductor Singapore Pte Ltd

Tech Semiconductor Pte. Ltd.

Yew Hoong Phang

Jianguang Chang

Jian Sun

Hing Ho Au

An improved design for a retaining ring for a chemical mechanical poling machine is described which provides superior flexibility and instantaneous in-situ control of the polishing rate in the edge region of a wafer. The design has a plurality of straight slurry delivery groves, angled in the direction of rotation of said ring wherein each alternate channel is recessed away from the inner circumference of the bottom, pad contacting, surface, of said retaining ring by a recess which extends upward from the bottom surface only sufficiently to prevent contact of the retaining ring with the polishing pad in the area of the recess. Each recess curves outwardly towards the inner circumference of the retaining ring in a manner to form a symmetrical segmented tab with a rounded edge, tangent to the inner circumference of the retaining ring, and meeting the inner circumference at the exit end of an adjacent non-recessed slurry channel. For a 200 mm. diameter wafer, having a total of 12 slurry channels, the total effective contact length of the resulting six segmented tabs is about 11.5% of the wafer perimeter. This is sufficient to properly contain the wafer during polishing and provides a large area of non distorted polishing pad at the wafer edge. By adjusting the operating pressures of the polishing head fitted with the improved retaining ring, it is possible to obtain polishing rates at the edge which are larger or smaller than the overall wafer polishing rate. The improved retaining ring provides a simpler and cheaper option for better wafer edge polishing rate as well as an increase is useable wafer area.

Retaining ring structure for edge control during chemical-mechanical polishing

The retaining ring has a plurality of slurry channels wherein each alternate channel is recessed away from the inner circumference of the pad contacting surface forming a recess which extends upward from the bottom surface sufficient to prevent contact of the retaining ring with the polishing pad. Each recess curves towards the inner circumference of the retaining ring in a manner to form a rounded tab, tangent to the inner circumference of the retaining ring, and meeting the inner circumference at the exit end of an adjacent non-recessed slurry channel. The total effective contact length of the ring with the wafer edge is about one-tenth of the wafer perimeter. This is sufficient to properly contain the wafer during polishing and provides a large area of undistorted polishing pad at the wafer edge. By adjusting the operating pressure of the polishing head, it is possible to obtain polishing rates at the wafer edge which are larger or smaller than the overall wafer polishing rate.

A thermal activated SACVD method for depositing a phosphorus oxide layer onto a silicon oxide wafer comprising the steps of: loading an SACVD device with a silicon oxide wafer; depositing a phosphorus doped oxide (PSG) layer on the USG layer using pure oxygen and a phosphorus and silicon source; purging the SACVD device; and depositing a boron and phosphorus doped oxide (BPSG) layer on the PSG layer.

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Singapore, Singapore

Yew Hoong Phang