Browse Prior Art Database

Chrome Mask Defect Detection

IP.com Disclosure Number: IPCOM000083222D
Original Publication Date: 1975-Apr-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Denk, HH: AUTHOR [+2]

Abstract

A method is described to permit frequent, rapid, and error-proof inspection of high volume chrome photolithographic masks.

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Chrome Mask Defect Detection

A method is described to permit frequent, rapid, and error-proof inspection of high volume chrome photolithographic masks.

Fig. 1 shows the positive photolithographic mask 1 which is to be inspected. A negative or mirror image mask 2 is produced by conventional photolithographic processing. The negative mask is stored at a mask inspection station for future use.

After the positive chrome mask has been employed in the photolithographic processing of semiconductor devices, the probability that defects produced by wear on the chrome film surface increases. Thereform, the in-process inspection of the positive mask becomes necessary to avoid the incidence of holes in the opaque chrome film, which would produce defects in the resulting semiconductor device.

Inspection of the positive chrome mask is simplified, by superimposing the negative chrome mask with the positive chrome mask and projecting light through the composite. The side of the composite opposite the projecting light is examined for the transmission of light. If light is found to be transmitted through any portion of the composite, a defect in the opaque chrome film of the positive mask is indicated.

Fig. 2 shows an unfolded view of the negative and positive relationship of the positive chrome mask 1 and the negative chrome mask 2.

The number of chip patterns with defects, N(D), determined by this tech-technique, can then be used to calculate a mask degradation factor, lambda, w...