METHOD OF DETECTING END POINT OF PLASMA ETCHING PROCESS

摘要

A method of detecting an end point of a plasma etching process for etching a first layer on a second layer is described, the first layer producing a first etching product and the second layer a second etching product. Time-dependent intensity [I_{j=1 to m}(t)] of a number "m" (m>=1) of spectral line(s) of the first etching product in emission spectrum of the plasma and that [I_{i=1 to n}(t)] of a number "n" (n>=1) of spectral line(s) of the second etching product in the emission spectrum are collected, wherein "m+n>=3" is satisfied. One index of $\mathrm{Lm}\left(t\right)\left[=\prod _{i=1,j=1}^{n,m}\frac{I_i\left(t\right)}{I_j\left(t\right)}\right],\mathrm{Ls}\left(t\right)\left[=\prod _{i=1,j=1}^{n,m}\frac{I_i\left(t\right)}{I_j\left(t\right)}\right],{\mathrm{Lm}}^{\text{'}}\left(t\right)\left\{=\left[\mathrm{Lm}\left(t\right)\right]/t\right\}\mathrm{and}{\mathrm{Ls}}^{\text{'}}\left(t\right)\left\{=\left[\mathrm{Ls}\left(t\right)\right]/t\right\}$ is calculated in real time and plotted with the time. An etching end-point is identified from the plot of the one index with the time.