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Simple Indicator of Image Sizes Produced by Photolithographic Processes

IP.com Disclosure Number: IPCOM000060036D
Original Publication Date: 1986-Feb-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 23K

Publishing Venue

IBM

Related People

Kleppinger, DD: AUTHOR

Abstract

By an operator viewing specially designed image size indicators (ISI) through a microscope, image sizes achieved in developed photoresist or etched images are measured. Alignment of a pair of edges in the ISI design pattern provides indication of image line and space width. A series of ISI may be designed and incorporated in photo masks to obtain any degree of measurement or control required. One possible design shape for ISI resulting in ease of assessment is shown in the figure. The shape is sized appropriately to match critical dimensions, i.e., the top projection width WP and the notch width WN are designed to result in dimensions nearly equal to those of a critical dimension desired in the process.

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Simple Indicator of Image Sizes Produced by Photolithographic Processes

By an operator viewing specially designed image size indicators (ISI) through a microscope, image sizes achieved in developed photoresist or etched images are measured. Alignment of a pair of edges in the ISI design pattern provides indication of image line and space width. A series of ISI may be designed and incorporated in photo masks to obtain any degree of measurement or control required. One possible design shape for ISI resulting in ease of assessment is shown in the figure. The shape is sized appropriately to match critical dimensions, i.e., the top projection width WP and the notch width WN are designed to result in dimensions nearly equal to those of a critical dimension desired in the process. The height of the top projection HP and of the notch HN are designed for operator convenience in determining alignment of edges LP with LN and edges RP with RN. The separation S is just large enough that expected variations in the process never cause S to go to zero and not much larger, again for operator convenience in the aforesaid edge-alignment judgement. In a photo process resulting in zero bias, the size of an image created is equal to the size of the mask object (in a one-to-one exposure system). The design shape shown in Fig. 1, where WP = WN, will be the same in the mask object and in the image resulting from a zero bias process. The left edges (1) of the top projection LP and (2) of the notch LN will be aligned, as will the right edges (1) of the projection RP and (2) of the notch RN. For assessing whether the nominal dimension actually...