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Method for the identification of reticle photo-induced contaminants and pellicle degradation

IP.com Disclosure Number: IPCOM000030173D
Publication Date: 2004-Jul-30
Document File: 5 page(s) / 216K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for the identification of reticle photo-induced contaminants and pellicle degradation. Benefits include improved functionality and improved performance.

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Method for the identification of reticle photo-induced contaminants and pellicle degradation

Disclosed is a method for the identification of reticle photo-induced contaminants and pellicle degradation. Benefits include improved functionality and improved performance.

Background

              With the introduction of 193-nm photolithography, an increase in photo-induced contaminants has occurred. A nondestructive technique is required to ensure the optical quality of the reticle and pellicle to increase their production life and improve the quality of the lithographic process.

              Residual SO4 ions from the cleaning process are the main cause of reticle crystal formation. Environmental sources contribute to haze formation.

              Pellicle wrinkling occurs due to the out gassing of inorganic impurities from the pellicle and/or pellicle frame under exposure. The degradation process leads to the formation of carboxyl and COF bonds (see Figure 1).

              Conventionally, pellicle failure is detected by a Fourier transform infrared (FTIR) technique when image resolution drops, line width increases, or pellicle appearance, including pellicle wrinkling, is changed prematurely and irreversibly before it reaches the end of its cycle. No early accurate detection of pellicle degradation exists.

 

General description

      The disclosed method is the early prediction of degradation of reticle and pellicle optical properties due to photo-induced contaminants. They are the result of exposure to 193-nm, 157-nm, or any other light wave length.

      The key elements of the disclosed method include:

•             Use of a nondestructive Fourier transform infrared (FTIR) technique to determine early signs of reticle optical quality degradation and polymer pellicle degradation due to the exposure to irradiation at any wavelength used for lithography

•             Rapid identification of potential fabrication environmental contaminants

Advantages

              The disclosed method provides advantages, including:
•             Improved functionality due to the improved identification of the contaminants

•             Improved performance due to the improvement of the image quality of the photomask
•             Improved performance due to the increase of  the reticle’s life

•             Improved performance due to the increase of  the pellicle’s life

Detailed description

      The disclosed method includes the use of FTIR. It is a nondestructive in-line technique that  identifies surface contaminants and confirms the composition of photo-induced haze/crystallization, which impact the optical quality of 193-nm reticles and pellicles.

      A producti...