Abstract
In order to prevent the deposition of evaporating materials onto the inner wall of deposition chambers, covering of the wall with plastic films has been proposed. In this case, the following conditions must be met for the plastic films : (i) Dissolved gases in the films can be easily removed, (ii) outgassing due to thermal decomposition is considerably low at below 300°C, and (iii) the sticking coefficients of vapors (evaporating materials) on the films must be unity.
Evaluation of two groups of heat-resisting films indicates that polyimide films almost fulfill the above requirements, except that they take more time to be evacuated than Teflon films. The outgassing rates due to thermal decomposition of polyimide films are lower than 10-9 Torr·1/cm2·sec at below 260°C, which lie between a tenth and a twentieth of those of Teflon films. The sticking coefficients of nickel and gold on polyimide films are close to unity from the onset of deposition, while those on Teflon films are extremely low, differing from those on other films.
