| dc.description.abstract | In the process of micro or nano electro mechanical system manufacturing, pattern collapse is widely observed during the cleaning process. By Surface Evolver simulation, the underlying mechanism of pattern collapse is explored. To avoid pattern collapse, the surface tension of the rinse liquid must be reduced. In experiment, different surfactants such as TTAB and Triton X-100 is added to the solution of hydrogen peroxide to reduce its surface tension. For TTAB and Triton X-100, the value of critical micelle concentration (CMC) for the solution of hydrogen peroxide is the same as that for water. Moreover, Triton X-100 is better than TTAB for the solution of hydrogen peroxide due to the achievement of the lower surface tension. Additionally, less Triton X-100 is needed to reach CMC and the side effect come from the interaction between surfactant and pattern can be reduced.
The decomposition of hydrogen peroxide (H2O2) can be affected by the acidity or basicity, temperature, impurity of an aqueous solution. In this study, the simple measuring system is employed to measure the temperature and pH value of an aqueous solution of H2O2. With the help of the heat balance equation, the decomposition rate associated with the stability of H2O2 under different temperature and time can be estimated. As the aqueous solution of copper (II) sulfate (CuSO4) is added, the decomposition of H2O2 is promoted due to the catalysis of copper (II) ion and large amount of heat is released, leading to the increase of the temperature of solution. Simultaneously, the decomposition of H2O2 can also be accelerated by increasing temperature. After a while, both temperature and pH value of the solution will increase significantly due to the rapid decomposition of acidic H2O2. By adding chelating agents such as EDTA and CDTA, the decomposition of H2O2 can be suppressed because of the binding of the metal ion by chelating agents. It is proved that stabilization ability of CDTA is better than that of EDTA, and stabilization ability can be promoted by much larger amount of chelating agent addition. For the aqueous solution of H2O2 and “basic” TMAH, the decomposition rate of H2O2 is accelerated due to the increase of pH value.
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