Browse Prior Art Database

Process for Making Electron-Beam Inspectable Masks

IP.com Disclosure Number: IPCOM000046215D
Original Publication Date: 1983-Jun-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Schmeckenbecher, AF: AUTHOR [+2]

Abstract

A scheme is employed for fabricating optical photomasks that generate the backscattered electron contrast required for high throughput defect detection using electron-beam inspection tools.

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Process for Making Electron-Beam Inspectable Masks

A scheme is employed for fabricating optical photomasks that generate the backscattered electron contrast required for high throughput defect detection using electron-beam inspection tools.

In order to inspect photomasks using E-beam tools, the photomasks must have patterns formed of a high atomic number, optically opaque material residing on an electrically conductive, optically transparent material, with the latter residing on the mask substrate. Typically, gold is used for the high atomic number, optically opaque material, while indium tin oxide is employed as the electrically conductive, optically transparent material residing on a quartz substrate.

A number of lengthy and cumbersome processes have been proposed for producing such optical photomasks that may be inspected by E-beam tools. However, all of the proposed schemes involve initial processing of a chrome- coated substrate with the subsequent addition of gold. A method is described here for directly producing the desired masks.

Indium tin oxide of appropriate thickness is deposited upon a quartz substrate of required thickness. Gold is then sputter deposited onto the indium tin oxide. This blank mask is then coated with any of the usual resists (photo or E-beam), the desired pattern is then exposed and developed, and the resist image is directly etched into the gold layer using a conventional alkaline cyanide solution. Appropriate time and temperature...