Browse Prior Art Database

Joystick Entry of Overlay Data

IP.com Disclosure Number: IPCOM000040339D
Original Publication Date: 1987-Oct-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Carey, ER: AUTHOR [+3]

Abstract

Vernier scales are employed on wafers during photolithographic operations to get precise alignment of overlay patterns with respect to one another and to the wafer. Using this joystick-entry technique, vernier values are entered directly into a computer for later analysis, improving data accuracy and cutting overlay inspection time. Overlay data is necessary at every level of the photolithographic process. It is ordinarily obtained by reading verniers on a wafer through a microscope, recording the vernier values, and centering them with a keyboard computer for analysis. Each chip has an overlay vernier in both X and Y directions, as shown in Fig. 1. The vernier pitch determines the values associated with the verniers. For example, in Fig.

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Joystick Entry of Overlay Data

Vernier scales are employed on wafers during photolithographic operations to get precise alignment of overlay patterns with respect to one another and to the wafer. Using this joystick-entry technique, vernier values are entered directly into a computer for later analysis, improving data accuracy and cutting overlay inspection time. Overlay data is necessary at every level of the photolithographic process. It is ordinarily obtained by reading verniers on a wafer through a microscope, recording the vernier values, and centering them with a keyboard computer for analysis. Each chip has an overlay vernier in both X and Y directions, as shown in Fig. 1. The vernier pitch determines the values associated with the verniers. For example, in Fig. 1, assuming a pitch of 10 microinches, the X value is +20 microinches and the Y value is -10 microinches (see arrows opposite centered readings). Vernier values were formerly read from a sample of chips (usually from 5 to 20 per wafer) by means of individual microscopic inspection, and recorded on a data sheet prior to entry into a computer for analysis. Here, one attaches a joystick to the game port of a personal computer, as in Fig. 2. X and Y values obtained from microscope viewing of object 1 by eye 2 are entered by hand 3 directly into the computer when read, freeing the operator from the need for writing data on a sheet. The X value is entered by tapping the joystick in the X direction the nu...