Browse Prior Art Database

Front Wafer Registration Device for Batch Process Etch End Point Detection System

IP.com Disclosure Number: IPCOM000089252D
Original Publication Date: 1977-Oct-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 4 page(s) / 99K

Publishing Venue

IBM

Related People

Khoury, HA: AUTHOR [+2]

Abstract

This device permits precise registration of the front (lead) wafer in a wafer carrier so that the optical axis of the end-point detection probe is coincident with the center of the product wafer test site to within tolerances permitting adequate worst-case pattern factor coverage.

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Front Wafer Registration Device for Batch Process Etch End Point Detection System

This device permits precise registration of the front (lead) wafer in a wafer carrier so that the optical axis of the end-point detection probe is coincident with the center of the product wafer test site to within tolerances permitting adequate worst-case pattern factor coverage.

The device (Figs. 1 and 2) consists of two pieces. Fig. 1 depicts the wafer holder 1 which embodies a wafer notch pin 6, a holder locating pin 5, and two holder indexing pins 3. Fig. 2 shows the preloading retaining clip 7, which embodies two centering pins 8.

These two pieces are used to accurately position and captivate the front (lead) wafer 10 in a 25-slot wafer carrier 19, so that the optical axis 37 of the end- point detection probe 25 is coincident with the center of the product test site 14 to within allowable translational and rotational tolerances which permit adequate worst-case pattern factor coverage.

In use, the front (lead) wafer 10 is lowered into the 25th slot 24 of the wafer carrier 19, and no attempt is made to register the wafer. The wafer position relative to the carrier is determined by the wafer interface points 32 on the carrier slot 24 and the axial play in the wafer slot. This seating arrangement is inadequate for proper end-point detection because tolerance build-up is excessive, inasmuch as the wafer is not registered relative to the "V"-notch 16.

This lack of registration causes the probe 25 optical axis 37 to be out of alignment relative to the process etch end-point detection test site 14.

As shown in Figs. 1 and 2, the wafer holder 1 and retaining clip 7 are used in the wafer carrier 19 to provide the necessary registration. This is in contrast to the technique of merely placing the wafer 10 into the lead slot 24. Accuracy here is possible because the notch pin 6 orients the wafer and restricts the Y-axis movement, and the retaining clip 7 centering pins 8 restrict X-axis movement and Theta(z) motion, and the preloading function restricts Delta Theta(x), Delta Theta(y) and Z-axis motion. The views slow the wafer 10 located by the notch pin 6 and two centering pins 8, and preloaded by the pads 9 on the retaining clip 7 against the 25th slot sidewalls. The pilot bushing 15 meshes precisely with the thru-hole in the wafer holder 2. Both the thru-hole 2 and carrier thru-hole 21 are referenced from the same reference surfaces 36 and 38. As shown in Figs. 1 and 2, the relationship of all the major components is illustrated above in their assembled and aligned position and mounted in the etching tank.

The wafer holder 1 is positioned above the wafer carrier 19 so that the carrier indexing pin 22 lin...