Thin film semiconductor device having arrayed configuration of semiconductor crystals

Abstract

A method for producing a thin film semiconductor device is described. In the method, a thin film layer of non-single-crystalline semiconductor, which is deposited on a base layer of glass, is processed to an island-shaped thin film layer at the time prior to the layer irradiation step. The laser irradiation to the thin film layer of non-single-crystalline semiconductor is carried out after forming an insulation film layer and a gate electrode over the island-shaped thin film layer, by using the gate electrode as the irradiation mask, whereby the center area of the island-shaped thin film layer masked by the gate electrode is crystallized, and simultaneously, the both side areas thereof which is not masked by the gate electrode are annealed. Next, a source electrode and a drain electrode is formed in the annealed areas. The implantation of impurity ion may be carried out either before or after the laser irradiation. By the above order of steps, it becomes possible to obtain a thin film semiconductor device which has small numbers of crystals and less variance of grain size of crystals for each unit of electric circuit, compared with a device produced by the conventional process. Further, the process makes it possible to be even the boundary surface between the crystallized layer and the insulation layer in a device.

1 - 9 . (canceled)  
   
   
       10 . A thin film semiconductor device, comprising: 
 a base layer of an insulation, material;    a thin film semiconductor layer formed on the base layer, and including a source electrode area, a drain electrode area and a channel area, the channel area having a grain size larger than a grain size of the source electrode area or the drain electrode area; and    a gate electrode formed above the channel area, said channel area being crystallized in a predetermined area by irradiation of a laser beam using the gate electrode as an irradiation mask.    
   
   
       11 . The thin film semiconductor device of  claim 10 , further comprising source and drain electrodes formed by filling contact holes formed in the gate insulation film layer at positions corresponding to the source area and the drain area with electrode material.  
   
   
       12 . The thin film semiconductor device of  claim 10 , wherein the channel area comprises a single crystal grain of large size.  
   
   
       13 . The thin film semiconductor device of  claim 10 , comprising a grain boundary in a center portion of the channel area.  
   
   
       14 . The thin film semiconductor device of  claim 10 , wherein the gate electrode comprises aluminum, polysilicon doped with phosphorus at high concentration, tungsten, TiW, WSi 2  or MoSi 2 .