Device having thin film transistor

Abstract

One or more elements selected from group III, IV or V are introduced into the amorphous silicon film, and then crystallized by heating at a temperature of 600° C. or lower. In a direction parallel to the substrate, crystals grow in the regions where the elements have been introduced. In a portion of the crystalline semiconductor layer, an active region of a semiconductor device is formed in such a manner that the relationship between the crystal growth direction and the device current direction is selected according to the desired mobility of the active region.

Description

technical field [0001] The present invention relates to a semiconductor device having a TFT (Thin Film Transistor) provided on an insulating substrate such as glass, and a method of manufacturing the semiconductor device. Background technique [0002] As semiconductor devices having TFTs formed on an insulating substrate made of glass or the like, there are known active liquid crystal display devices, image sensors, etc., which use TFTs to drive pixels. [0003] The TFTs used in these devices are typically silicon thin film semiconductors. Silicon thin film semiconductors can be roughly classified into amorphous silicon semiconductor (a-Si) type and crystalline silicon semiconductor type. Because the manufacturing temperature of amorphous silicon semiconductor is relatively low, it is usually used more often. It is easier to manufacture by vapor phase method, and the mass production rate is higher. However, since the physical properties of amorphous silicon semiconductors,...

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Problems solved by technology

[0008] However, in the method (1), it is technically difficult to uniformly form a film having excellent semiconductor physical properties on the entire surface of the substrate

Moreover, since the film formation temperature is high, that is, above 600°C, there is a cost problem, that is, an inexpensive glass substrate cannot be used

In the method (2), in the case of the excimer laser which is most commonly used at present, there is a problem that the productivity is low because the area irradiated by the laser beam is small

When such a large-scale glass substrate is used, a series of problems will arise, that is, in the heat treatment process of manufacturing this semiconductor, the shrinkage or deformation of the substrate will cause the accuracy of mask matching to decrease

In particular, in the case of the most commonly used 7059 glass at present, the temperature of the deformation point is 593°C, so the traditional thermal crystallization method will greatly deform the substrate

In addition, in addition to the temperature problem, since the current process requires tens of hours of heating time to meet the requirements of crystallization, it is also necessary to shorten the heating time

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