Other

The University of New Mexico

Kenneth P Bishop

John R McNeil

S Sohail Naqvi

Steven Roy Julien Brueck

Bruce L Draper

Brian R Stallard

Gary D Tipton

Susan M Gaspar

Kirt C Hickman

Lisa M Milner

Michael P Summers

The present invention includes a method and apparatus for the rapid, nondestructive evaluation of the contrast of a latent image in a photoresist. More particularly, the contrast of the latent image is directly monitored by measuring the intensity of the light diffracted from a pattern in the exposed, undeveloped photoresist known as the latent image. The proper exposure tool parameters, such as exposure tool time and focus, is suitably determined based on the intensity of different orders of diffracted light, namely the 2nd-order diffracted from the latent image. In a preferred embodiment, a test pattern consisting of a periodic pattern, or a pattern of the device associated with the particular lithographic step, is employed to provide well-defined diffraction orders.

Use of diffracted light from latent images in photoresist for optimizing

In microelectronics manufacturing, an arrangement for monitoring and control of exposure of an undeveloped photosensitive layer on a structure susceptible to variations in optical properties in order to attain the desired critical dimension for the pattern to be developed in the photosensitive layer. This is done by ascertaining the intensities for one or more respective orders of diffracted power for an incident beam of radiation corresponding to the desired critical dimension for the photosensitive layer as a function of exposure time and optical properties of the structure, illuminating the photosensitive layer with a beam of radiation of one or more frequencies to which the photosensitive layer is not exposure-sensitive, and monitoring the intensities of the orders of diffracted radiation due to said illumination including at least the first order of diffracted radiation thereof, such that when said predetermined intensities for the diffracted orders are reached during said illumination of photosensitive layer, it is known that a pattern having at least approximately the desired critical dimension can be developed on the photosensitive layer.

Diffracted light from latent images in photoresist for exposure control

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Rio Rancho, NM, United States of America

Kenneth P Bishop