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Process and Quality Control of Polymer Pellicles

IP.com Disclosure Number: IPCOM000022118D
Publication Date: 2004-Feb-25
Document File: 3 page(s) / 376K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for the non-destructive process control of polymer pellicles during production. The disclosed method uses non-destructive contact angle measurements to characterize changes in pellicle properties caused by exposure to irradiation at any wavelength. Benefits include using the established correlation between the value of the contact angle and irradiation exposure dose at a particular wavelength.

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Process and Quality Control of Polymer Pellicles

Disclosed is a method for the non-destructive process control of polymer pellicles during production. The disclosed method uses non-destructive contact angle measurements to

characterize changes in pellicle properties caused by exposure to irradiation at any wavelength.

Benefits include using the established correlation between the value of the contact angle and irradiation exposure dose at a particular wavelength.

Background

Pellicles are used to protect the mask from particle contamination. Pellicles are placed a certain distance from either, the front side of the mask or on both the front and back sides and, ideally, should be transparent to the incoming laser/light source. If a pellicle is not absolutely transparent to the incoming light, but transmission is close to 100% (e.g. 98%), the correction of the irradiation dose takes into account non-transparency by increasing the dose. The radiation dose depends on linear transmission. The dose should be uniform over the surface of the pellicle and wafer and, ideally, should not change. Non-uniformity of the dose causes changes in the critical dimensions (CD) of the resist (see Figure 1). Direct measurements of pellicle transmission are done using a radiation source (such as a laser) or UV lamp, a detector, and a specially designed chamber. It is not practical to conduct the routine monitoring of transmission changes in the fabrication environment.

Currently, there is no non-destructive estimation of pellicle service life to verify pellicle properties; Pellicle service life is estimated based on durability data collected during the material development stage.

General Description

In the disclosed method, an accurate correlation between pellicle transm...