Browse Prior Art Database

Sensing Pin Notch Alignment in a Wafer Positioning System

IP.com Disclosure Number: IPCOM000080009D
Original Publication Date: 1973-Oct-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Ananthakrishnan, RB: AUTHOR [+3]

Abstract

In an automatic wafer positioning system, the wafer 10 must be aligned with a pin 12 in the chuck 14. This is accomplished at the proper time in the logic cycle by rotational and directional air jets, which rotate the wafer 10 and push it against the pin 12 simultaneously. This operation continues until a notch 14 in the wafer is fitted around the pin 12. An alignment sensing arrangement is provided such that the logic gets word that the above-described alignment has taken place. It should be noted that no white light should come in contact with the wafer, since this would expose the photoresist on the wafer.

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Sensing Pin Notch Alignment in a Wafer Positioning System

In an automatic wafer positioning system, the wafer 10 must be aligned with a pin 12 in the chuck 14. This is accomplished at the proper time in the logic cycle by rotational and directional air jets, which rotate the wafer 10 and push it against the pin 12 simultaneously. This operation continues until a notch 14 in the wafer is fitted around the pin 12. An alignment sensing arrangement is provided such that the logic gets word that the above-described alignment has taken place. It should be noted that no white light should come in contact with the wafer, since this would expose the photoresist on the wafer.

Referring to Fig. 1, the wafer 10 and pin 12 are shown in the unaligned position, that is, with the notch 14 not aligned with the pin 12. Fig. 2 shows the same wafer 10 when it is aligned, that is, notch 14 is positioned around pin 12. The wafer not in position is superimposed on Fig. 2 to show the differences in position between the aligned and nonaligned wafer. It should be noted that the shaded area in Fig. 2 is covered by the wafer only when the wafer is aligned with the pin. Two sensing diodes 16 are mounted in the chuck 14 adjacent the pin 12 within the shaded area in Fig. 2.

An infrared light source 18 is arranged in Fig. 3 such that when the Bernoulli arm is in position over the chuck, light from the light source 18 is reflected by prism 20, which is located in the Bernoulli head 21, so that t...