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Reducing Bias and Tolerance of Developed Positive Photoresist Images

IP.com Disclosure Number: IPCOM000085643D
Original Publication Date: 1976-May-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Hood, FP: AUTHOR [+3]

Abstract

The bias, or the increase in the developed image size relative to the exposure mask pattern, and tolerance, or the variation of a given image dimension, are reduced for alkali soluble novolak resin and diazo ketone sensitizer based positive photoresists. The resist layers contain optimized sensitizer concentrations and the images are generated using an overexposure, overdevelop mode.

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Reducing Bias and Tolerance of Developed Positive Photoresist Images

The bias, or the increase in the developed image size relative to the exposure mask pattern, and tolerance, or the variation of a given image dimension, are reduced for alkali soluble novolak resin and diazo ketone sensitizer based positive photoresists. The resist layers contain optimized sensitizer concentrations and the images are generated using an overexposure, overdevelop mode.

Resists are used in which the sensitizer is present in optimized amounts of 30 to 35 percent by weight of resist solids. As an example, resist layers are spin coated on oxidized cleaned wafers (3 seconds, 4400 RPM), and then baked for 20 minutes at 80 degrees C.

The layers are exposed through a mask to partially coherent monochromatic light (4358 Angstrom) for 300 milliseconds at 175 MW/cm and developed in standard alkaline developer for 30 seconds. The results of line width and tolerance measurements printed from a nominal 100 Mu'' positive mask line, are as follows:.

Wafer No. Control 1 2 3 4 Oxide thickness Angstrom) 4145 4150 4140 4145 4060 Resist thickness Angstrom) 10752 10782 10859 10480 12813 Sensitizer level % 22 30 30 32.5 35 x(Mu'') (By wt. in solids) 103 79.2 77.9 68.9 57.9* (Mu'') 13.75 8.1 4.77 2.3 3.18 *Resist residue

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