Browse Prior Art Database

Method to Increase Sensitivity of Negative Resists

IP.com Disclosure Number: IPCOM000062569D
Original Publication Date: 1986-Dec-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Maldonado, JR: AUTHOR [+2]

Abstract

A method for increasing the throughput of X-ray lithography systems or electron beam systems using negative resists is provided wherein entire resist-covered wafers are pre-exposed to a relatively low flux. It has been found that a low dose of radiation does not cause a substantially thicker resist layer to remain after development in areas which are not further exposed to radiation. Thus, by pre-exposing the entire resist-covered wafer to a low dose of radiation, the dose in pattern regions intended to be exposed can be correspondingly reduced during exposure with a mask. As a result, throughput is improved, thereby effectively increasing resist sensitivity.

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Method to Increase Sensitivity of Negative Resists

A method for increasing the throughput of X-ray lithography systems or electron beam systems using negative resists is provided wherein entire resist-covered wafers are pre-exposed to a relatively low flux. It has been found that a low dose of radiation does not cause a substantially thicker resist layer to remain after development in areas which are not further exposed to radiation. Thus, by pre- exposing the entire resist-covered wafer to a low dose of radiation, the dose in pattern regions intended to be exposed can be correspondingly reduced during exposure with a mask. As a result, throughput is improved, thereby effectively increasing resist sensitivity. The exposure characteristics of a typical X-ray negative resist are seen in the figure with the fractional thickness remaining after exposure and development, and the incident energy (millijoules per square centimeter) as the axes. While the relationship between the incident energy and remaining thickness is linear where the incident energy is greater than approximately six millijoules per square centimeter, a nonlinear effect is seen therebelow. From the figure it is evident that with an incident energy of approximately three millijoules per square centimeter or less, the resist thickness remaining after exposure and development decreases only nominally with less exposure, with a thin resist layer on the order of a few hundred Angstroms remaining. Thus, by pre-exposing the entire resist covered wafer to a low...