1. Field of Invention
The present invention relates to liquid crystal panels and liquid crystal panels, and in particular, a technology suitable for active matrix liquid crystal panels in which pixel electrodes are switched with switching elements formed on a semiconductor substrate or an insulating substrate. The present invention also relates to an electronic device and a projection display device using the same.
2. Description of Related Art
Liquid crystal panels having a structure in which a thin film transistor (TFT) array using amorphous silicon is formed on a glass substrate have been conventionally used as reflective active matrix liquid crystal panels which are used in light valves of projection display devices.
The active matrix liquid crystal panel using the TFT is a transmissive liquid crystal panel, and a pixel electrode is formed with a transparent conductive film. In transmissive liquid crystal panels, since the switching element-forming region, such as a TFT, which is provided in each pixel is not a transparent region, it has a serious defect that the aperture ratio is low and decreases as the resolution of the panel is improved to XGA, or S-VGA.
As a liquid crystal panel having a smaller size than the transmissive active matrix liquid crystal panel, a reflective active matrix liquid crystal panel in which pixel electrodes, as reflecting electrodes, are switched with transistors formed on a semiconductor substrate or an insulating substrate has been proposed.
In such a reflective liquid crystal panel, the formation of a passivation film as a protective film on the substrate in which the reflecting electrodes are formed is often omitted since it is not always necessary. The present inventor has studied the formation of a passivation film on a reflective liquid crystal panel substrate.
In general, a silicon nitride film formed by a low pressure CVD process or a plasma CVD process is often used as a passivation film in semiconductor devices. The passivation film formed by a current CVD process inevitably has some variation of the thickness of approximately 10%. Accordingly, the reflective liquid crystal panel has disadvantages, e.g. the reflectance noticeably varies with variation of the thickness of the passivation film.