The Experimental Study Of Low Pressure CCP By Optical Emission Spectroscopy Diagnostics

Plasma processing is very important in the semiconductor manufacturing industry.The increased uniformity and etching rate of plasma can not only reduce costs,but also improve the productivity and yield.Langmuir probe and Optic emission spectroscopy(OES)were widely used for the study of plasma properties.Using OES,the effects of discharge gas type,plate electrode configuration and discharge parameters on the intensity of the emission spectrum were studied in this paper.The relationship between emission intensity and electron temperature,electron density and photoresist etch rate has also been studied based on current and previous work.This article is divided into the following sections:(1)Study on the optic emission intensity of capacitive coupled Argon plasmaIn this section,the effects of power,pressure and electrode configuration on the excitation intensity of argon ion(488nm)and argon atom(750nm)were studied.The electrode configuration includes the electrode gap and the electrode type.The relationship between the optic emission intensity of the excited argon ions and argon atoms and the measured Langmuir probe data(electron temperature,electron density and electron energy density from previous work)were discussed Furthermore,the relation between emission intensity and etch rate was studied.The result indicates that there is a linear relationship between the emission intensity of argon ions and the emission intensity of argon atoms(R2=0.99)when the pressure is constant,and the intensity increased linearly with the increase of input power.The correlation between the emission intensity of the argon ions and argon atoms and electron density/electron energy was higher than 0.95.The correlation between the emission intensity of the argon and the etch rate of the photoresist was high to 0.99.An increase of the electrode distance leads to the decrease of the emission intensity of argon ions and argon atoms.As a result,decreases the etching rate.(2)Study on the optic emission intensity of capacitive coupled Oxygen plasmaThe same experiment was carried out by changing the discharge gas to oxygen.It was found that the results was same as those of the argon under constant pressure.However the reaction was complicated because oxygen was a two-atom electronegative gas.At constant power,the correlation between the emission intensity of the oxygen and the electron temperature/the electron density/the electron energy density was poor,and the dependence of the etching rate of the photoresist was also poor.The uniformity of the etching rate of photoresist had little effect in the different pressure.(3)Study on the optic emission spectroscopy of the capacitive coupled plasma with mixed gases of argon and oxygenThe result indicates that there is a maximum oxygen emission intensity when oxygen concentration reaches to about 8%,in which the highest etch rate also be found in the vicinity.In the mixed gas discharge,the emission spectrum for the qualitative diagnosis of photoresist etching is also feasible,some discussion is provided in this thesis.