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Simplified Self Aligning Mask Device Configuration

IP.com Disclosure Number: IPCOM000085156D
Original Publication Date: 1976-Feb-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Feder, R: AUTHOR [+2]

Abstract

A method is employed for obtaining a perfect alignment for multiple mask registrations, wherein the mask that is used is an X-ray mask composed of different materials having different X-ray absorption characteristics for different, or the same wavelength, X-ray radiation.

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Simplified Self Aligning Mask Device Configuration

A method is employed for obtaining a perfect alignment for multiple mask registrations, wherein the mask that is used is an X-ray mask composed of different materials having different X-ray absorption characteristics for different, or the same wavelength, X-ray radiation.

The basic idea of this method is to transmit radiation through the mask and substrate to expose a layer of resist on the front surface of the substrate. The X- rays that expose the resist are those not absorbed by the masking material. By choosing the materials used for the mask as well as the X-ray wavelengths, each part of the mask acts as a bandpass filter. The filtering action is calculated from the X-ray absorption characteristics of the metals composing the mask.

Figs. 1a to 1f show how a conducting stripe of metal is deposited over a metal base with a stripe of insulation interposed between the two metals. Mask 2 is composed of a gold block 4 whose central portion is partially cut out. Across the cutout portion of the gold is imbedded a stripe of rhodium 6. In contact with the mask is a silicon substrate 8 and onto which is coated a layer 10 of resist. The resist is exposed through the mask with AlK Alpha X-rays (wavelength of 8.3 Angstroms).

Fig. 3 is a plot of the absorption coefficient of metal for a given wavelength of X-rays. It is seen from that plot that at 8.3 Angstroms rhodium and gold have substantially the same absorption coeff...