Effects of Silicon Implantation and Processing Temperature on Performance of Polycrystalline Silicon Thin-Film Transistors Fabricated from Low Pressure Chemical Vapor Deposited Amorphous Silicon

1987 ◽  
Vol 106 ◽  
Author(s):  
Anne Chiang ◽  
Tiao Y. Huang ◽  
I-Wei Wu ◽  
Mark H. Zarzycki ◽  
Mario Fuse

ABSTRACTSilicon implantation has been found to dramatically enhance the grain size of polysilicon crystallized from LPCVD a-Si by retarding the nucleation process at the substrate interface. Corresponding improvement in TFT device performance was also observed, resulting in field effect mobilities as high as 109 cm2/Vs in devices with 1000 Å thick Si active layer. This effect is more significant in device fabrication processes with higher temperature, possibly due to increasingly efficient removal of implant related defects.

1991 ◽  
Vol 238 ◽  
Author(s):  
Paul G. Snyder ◽  
Yi-Ming Xiong ◽  
John A. Woollam ◽  
Eric R. Krosche

ABSTRACTVariable angle spectroscopie ellipsometry (VASE), a nondestructive optical technique, was used to characterize two different multilayer samples, each having a low-pressure chemical vapor deposited polycrystalline silicon (poly-Si) layer. Analysis of these samples by cross-sectional transmission electron microscopy (XTEM) revealed large changes in grain size, between the undoped, as-deposited, and doped, annealed poly-Si layers. Roughness at the top of the poly-Si layers was also observed by XTEM. These features, together with the other structure parameters (thickness and composition), were analyzed ellipsometrically by fitting the measured VASE spectra with appropriate multilayer models. Each composite layer (surface overlayer, interfacial layer, and poly-Si layer) was modeled as a physical mixture, using the Bruggeman effective medium approximation. The ellipsometrically determined thicknesses were in very good agreement with the corresponding results measured by XTEM. Furthermore, VASE analysis provided additional information about the relative fractions of the constituent materials in the different composite layers. Thus, it quantitatively characterized the surface and interracial properties, and also the doping and annealing effects on the microstructure of poly-Si layers.


1983 ◽  
Vol 42 (2) ◽  
pp. 171-172 ◽  
Author(s):  
N. Lewis ◽  
G. Gildenblat ◽  
M. Ghezzo ◽  
W. Katz ◽  
G. A. Smith

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