A study of organic contamination control on photomask surface for 65nm tech node

In recent years, organic compounds have been clarified as one of major root causes of the haze, and carbon and amine components are major of them to organize. Therefore, both two should be controlled simultaneously for preventing haze defects on photomask. It is well known that UV/O3 treatment has a strong efficiency of removing organic matters1. For that reason, we have inserted it into our cleaning process, especially for EA.PSMS. And the surface variation of mask, after UV/O3 treatment, has been confirmed by the change of surface free energy on it. And organic matters remaining on mask surface have been identified by Gas Chromatography Mass Spectrometry (GC MS) with two different sample preparation methods: Thermal Desorption (TD) and direct extraction. As a result of UV/O3 treatment, we confirmed that it has an excellent removing efficiency of aromatic compounds and semi-volatile organics on mask surface. Finally, through the haze accelerating tests, we have known that conventional SPM/SC-1 cleaning with UV/ O3 treatment has been having a much higher threshold energy value in terms of causing haze defects on masks about 20 times higher than that of the cleaning with just SPM/SC-1.