Characterization and Modeling of Out‐Diffusion of Manganese and Zinc Impurities from Deep Ultraviolet Photoresist

Abstract

The radioactive tracer technique was applied to investigate the out-diffusion of manganese and zinc impurities from deep-ultraviolet (DUV) photoresist. Two important process parameters, viz., baking temperature and the type of substrate (i.e., bare silicon, polysilicon, oxide, or nitride), were evaluated. Our results indicated that diffusion ratios were all below 6%, irrespective of the substrate type and baking temperature. The substrate type did not appear to strongly affect the metallic impurity out-diffusion from DUV photoresist. However, solvent evaporation was found to have a significant effect on impurity diffusion. A new model, together with a new parameter, was proposed to describe the out-diffusion behavior of impurities from DUV photoresist. This model could explain the diffusion ratio of metallic impurities in photoresist layers under various baking conditions. The effectiveness of various wet cleaning recipes in removing metallic impurities such as manganese and zinc was also studied. It was found that (i) bath life due to temperature change can considerably affect the cleaning efficiency, and (ii) hot water immersion can effectively dissolve the impurities from the wafer surface.

Modifications of surface materials and their effects on cleanability as studied by radiochemical methods

“…Sensitive to humidity and temperature, lower energy resolution Ohlson and Wäänänen 1971, Jokelainen and Uusi-Rauva 1976a, 1976b, 1979, Jokelainen et al 1982, Pesonen-Leinonen et al 2006a HPGe-detector Surface High energy resolution Low detection efficiency Wang et al 1999, Lu et al 2000 Radiochemical model soils consist of bulk soil matter, labelled radioisotope and solvent. The model soils used should contain typical components of the environment of the evaluated materials.…”

Application of radiochemical determination methods in cleanability research of building materials

“…Height of pulse is proportional to the emitted energy of a particle Benvenuti et al (1999) Scintillation detector (NaI(Tl)-crystal) g Scintillation properties NaI(Tl)-crystal Gamma interactions. Crystal emits light when gamma rays interact with atoms in the crystals Jokelainen et al (1982), Jokelainen andUusi-Rauva (1976a,b, 1979), Kymäläinen et al (2008), Määttä et al (2007aMäättä et al ( ,b,c, 2008Määttä et al ( , 2009 (2000), Wang et al (1999Wang et al ( , 2001 Benvenuti et al (1999) Chromium oxide þ triolein Liquid scintillation counter Kymäläinen et al (2008), Määttä et al (2007aMäättä et al ( ,b,c, 2008Määttä et al ( , 2009 NaI(Tl)-crystal were generally used for the determinations in cleanability studies. In addition a GM-detector and a proportional counter and HPGe-detector (Table 2) have been used for measuring cleaning of surfaces.…”

“…Radiochemical methods have also been used to compare the cleaning efficiencies of detergents on PVC, chromium and steel surfaces (Benvenuti et al, 1999) and to compare cleaning methods for removing metallic impurities (Lu et al, 2000;Wang et al, 1999Wang et al, , 2001. In addition, radiochemical methods have been used in some laundering studies (Morris and Prato, 1985;Shebs, 1987).…”

“…High detection efficiency, sample geometry has no effect Sample is destroyed, sample colour and composition can have an effect Jokelainen et al (1982), Kymäläinen et al (2008), Määttä et al (2007aMäättä et al ( ,b,c, 2008 Proportional counter Surface Sample is not destroyed, sample's colour and composition have no effect Adhered activity cannot be observed (low energy of b) Benvenuti et al (1999) Gamma spectrometry NaI(Tl)-crystal Surface Sample is not destroyed, also detects adhered activity, sample's colour and composition have no effect Low energy resolution Jokelainen andUusi-Rauva (1976a,b, 1979), Jokelainen et al (1982), Kymäläinen et al (2008), Määttä et al (2007aMäättä et al ( ,b,c, 2008Määttä et al ( , 2009 High energy resolution, sample's colour and composition have no effect Low detection efficiency Lu et al (2000), Wang et al (1999Wang et al ( , 2001 above, the results from the radiochemical and the supporting methods partly correlated with each other. In the study by Kymäläinen et al (2008) there was a significant correlation between the cleanabilities of the surfaces from both radiochemical soiling materials (soil residue %) and manure soiling materials: Pearson's correlation coefficient was r ¼ 0.656 for radiochemical soiling material 1 (inorganic particle and oil soiling material with 51 Cr) and manure soiling material in the colorimetric measurement, and r ¼ 0.691 for radiochemical soiling material 2 (inorganic particle and oil soiling material with 14 C) and manure soiling material.…”

“…Energy level is much higher compared to 51 Cr, which means that the isotope is not as safe as 51 Cr. Half-life is too short Wang et al (2001) 65 Zn b þ /g 1.115 (g) 245 d Energy level is much higher and half-life longer compared to 51 Cr, which means that the isotope is not as safe as 51 Cr and the disposal process is complicated Wang et al (1999) 137 Cs b À /g 0.6616 (g) 30 y Energy level is higher and half-life longer compared to 51 Cr, which means that the isotope is not as safe as 51 Cr and the disposal process is complicated Lu et al (2000) EC ¼ electron capture. a Information from Lederer et al (1967). but chemical composition of the surface material was also considered to be important.…”