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Method for resist characterization

IP.com Disclosure Number: IPCOM000130473D
Publication Date: 2005-Oct-24
Document File: 5 page(s) / 302K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for resist characterization. Benefits include improved functionality and improved reliability.

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Method for resist characterization

Disclosed is a method for resist characterization. Benefits include improved functionality and improved reliability.

Background

      Conventionally, lithographic processes are inconsistent in their capability to repeatedly produce consistent results. No standardized procedure exists of testing and correlating the properties of resist materials in solution.

      To ensure the reproducibility and repeatability of lithographic processes, the resist properties of resist materials from various suppliers or from different production batches of the same supplier must be characterized. Conventionally, semiconductor manufacturers must rely on data from the supplier about the resist material in solution. However, resist properties change after deposition and baking. Heat flow during heating is distributed differently for deposited resist than for free-standing resist. The preparation of the samples includes mechanical scrapping of resist from the wafer, which can change the resist properties. Additionally, deposition and thermal treatment conditions cannot be reproduced at the supplier’s sites.

General description

              The disclosed method accurately characterizes resist resin by characterizing a resist layer spun on a wafer. Processed resist material is analyzed using thermal gravimetric analysis (TGA) crucibles or differential scanning calorimetry (DSC) pans.

Advantages

              The disclosed method provides advantages, including:
•             Improved functionality due to ensuring the reproducibility and repeatability of lithographic processes

•             Improved functionality due to enabling the standardization of testing the properties of the resist material for consumables and the lithography/bake processes

•             Improved reliability due to enabling the ensuring of the reproducibility and repeatability of lithographic processes

Detailed description

      The disclosed method includes the analysis of resist material that has been deposited on the wafer and baked. Resist is scrapped from the wafer, placed in the TGA crucibles or DSC pans, and tested. Additional resist in solution is left in the vacuum oven at a temperature of 40º to 50ºC so the solvent evaporates. The residual resist, which is a powder, is tested using a TGA and a DSC.

              The disclosed method can be verified by experimentation. Resist deposited on bare silicon wafers at a layer thickness of 2200A is baked for 1.5 minutes at 130ºC. Resist formed from the solution is baked at 130ºC for a time ranging from zero to 20 minutes. DSC and TGA traces are compared for resist from the wafer and resist from the solution.

              The results of the experiment indicate the following:

•             A correlation exists between the DESC and TGA data from resist from the wafer and from solution.

•             For each resist type, certain correction factors should be utilized to establish the correlation between res...