Semiconductor device fabrication method and semiconductor device fabrication system for minimizing film-thickness variations
View Patent ↗A polishing-rate distribution of a target film is compared with a desired post-polishing film-thickness distribution of the target film, thereby obtaining a pre-polishing film-thickness distribution of the target film by a reverse calculation, so that film growing conditions can be controlled in advance so as to allow the target film to have, after polishing, a film-thickness distribution that is the same as the desired film-thickness distribution. Therefore, even if there is a possibility that variation in the step height of the wafer surface might be produced by polishing, the finally obtained target film's film-thickness distribution can be the desired film-thickness distribution. Accordingly, semiconductors in which device-to-device variation in characteristic is reduced can be provided.
1. A method for fabricating a semiconductor device comprising the steps of:
(a) setting a polishing-rate distribution of a target film formed on a wafer and a desired post-polishing film-thickness distribution of the target film;
(b) calculating a pre-polishing film-thickness distribution of the target film based on the polishing-rate distribution and the desired film-thickness distribution;
(c) forming the target film having the pre-polishing film-thickness distribution of the target film; and
(d) polishing the target film.
2. The method of claim 1 , further comprising the steps of:
(e) measuring a film-thickness distribution of the target film formed on the wafer, before the step (d) is performed;
(f) measuring the film-thickness distribution of the target film, after the step (d) is performed; and
(g) updating the polishing-rate distribution based on the film-thickness distribution of the target film obtained in the step (e) and based on the film-thickness distribution of the target film obtained in the step (f), after the step (f) is performed.
3. The method of claim 2 , wherein the steps (a) through (g) are repeated.
4. The method of claim 3 , wherein a test wafer is used in the initially performed step (a).
5. The method of claim 1 , wherein the target film is formed by a plasma CVD process in the step (c).
6. The method of claim 1 , further comprising a plurality of steps, before the step (c) is performed.