Patent ID: 8625111
Filing Date: 2014-01-07
Classification: C23C,G01B

Abstract:
1. An optical film thickness meter which measures an optical film thickness by allowing measurement light to pass through an actual substrate, comprising: a light projector which emits outgoing light as the measurement light toward the actual substrate; a reflection mirror which reflects the outgoing light at a position on a side opposite to the light projector relative to the actual substrate; a light receiver which receives the measurement light which passes through the actual substrate, is reflected by the reflection mirror, and passes through the actual substrate; and a light detector which detects the measurement light received by the light receiver, wherein the actual substrate is disposed between the reflection minor and the light projector so that a perpendicular line to a film formation surface of the actual substrate has a predetermined angle with respect to an optical axis of the measurement light so that the light receiver receives the measurement light having passed through a first path of the actual substrate, reflected by the reflection mirror and then having passed through a second path of the actual substrate a second time, wherein at least one spot on the actual substrate in the first path is the same as at least one spot on the actual substrate of the second path.