Use of Catalyzed Hydrogen Peroxide (CHP) Chemical System for Stripping of Implanted State-of-the-Art UV Resists

Case ID:

This invention addresses the use of Catalyzed Hydrogen Peroxide (CHP) chemical systems at low temperatures, less than 80°C, for disrupting crust formed on deep UV resist layers so that the underlying resist layer can be removed easily. Systematic investigation of variables such as hydrogen peroxide and catalyst concentration and time has led to the development of an optimal formulation for attacking the crust. It has been found that effective removal of high dose implanted PR is possible by first exposing the resist to CHP solution at room temperature followed by immersion in 2:1 sulfuric acid-peroxide mixture (SPM) at 80°C.


Photoresist is typically employed as block mask during ion implantation for front-end-off-line (FEOL) CMOS device processing. Removal of resists exposed to ions during this processing is currently carried out by an oxygen plasma ash method followed by a wet stripping process. Dry stripping methods using oxygen plasma cause particulate contamination and silicon loss and need a follow up wet cleaning step. All wet cleaning methods based on high temperature sulfuric acid-peroxide mixtures (SPM) appear to overcome some of the limitations of dry stripping but still are not very effective in removing carbonized crusts formed by implanted resists at dosages greater than 1016/cm2. Further, high temperature and extreme low pH conditions used in SPM based resist stripping pose a serious safety concern. Eliminating the ash and reducing the temperature of the wet chemical strips will reduce the energy footprint of the strip and simultaneously reduce the number of process steps.


  • Much less energy intensive and more environmentally friendly
  • Reduces the high temperature and extreme low pH conditions used in SPM based resist stripping pose which is a serious safety concern


  • Semiconductor and electronics industry
  • UV photoresist stripping
Patent Information:
Contact For More Information:
Tariq Ahmed
Sr Licensing Manager, College of Engineering
The University of Arizona
Lead Inventor(s):
Srini Raghavan
Rajkumar Govindarajan
Manish Keswani