Browse Prior Art Database

Manual Intervention of an Automatic Alignment System

IP.com Disclosure Number: IPCOM000080294D
Original Publication Date: 1973-Nov-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 3 page(s) / 47K

Publishing Venue

IBM

Related People

Appenzeller, HA: AUTHOR [+2]

Abstract

A means is provided for manual intervention and alignment correction of a computer controlled automatic wafer-to-mask alignment system.

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Manual Intervention of an Automatic Alignment System

A means is provided for manual intervention and alignment correction of a computer controlled automatic wafer-to-mask alignment system.

A closed-circuit television system is added to the automatic alignment system in such a manner that after each automatic alignment cycle, the operator will be able to verify the accuracy of the alignment by inspecting the overlay of alignment targets on the mask and wafer. The operator is provided with controls for manual operation of the alignment stage, in the event that the automatic alignment is not within specification. In either automatic or manual mode, stage 1, Fig. 1, is rough positioned in the X and Y axes by stepping motors 2 that provide 62 microinches per step, and fine positioned by piezoelectric transducers 3 that provide 0.7 microinches per step.

The operator controls consist of lever switches 4 to control the stepping motors and piezoelectric transducers (PZM's) with the aid of the clock 5 and computer 6. The switches are so constructed that increased side pressure causes several contacts to close sequentially, and is bidirectional in that a different set of contacts is closed when the switch lever is pushed to the right, than is made when the lever is pushed to the left.

Clock 5 constantly sends strobe pulses to each of the lever switches to interrogate the position of the switches. If the switches are in the center-off position, no action is taken by the computer 6 and the stage does not move. If one or more of the switches is actuated at the time the strobe pulse is sent out, the pulse will be received back by computer 6 through the switch contacts. Computer 6 will sense...