Polycrystalline Si Films Fabricated by Low Temperature Selective Nucleation and Solid Phase Epitaxy Process

1997 ◽  
Vol 485 ◽  
Author(s):  
Claudine M. Chen ◽  
Harry A. Atwater
Keyword(s):  
Thin Film ◽  
Grain Size ◽  
Crystal Growth ◽  
Incubation Time ◽  
Solid Phase ◽  
Solid Phase Epitaxy ◽  
Grain Sizes ◽  
Random Nucleation ◽  
Nucleation Sites ◽  
Si Films

AbstractWith a selective nucleation and solid phase epitaxy (SNSPE) process, grain sizes of 10 μm have been achieved to date at 620°C in 100 nrm thick silicon films on amorphous SiO2, with potential for greater grain sizes. Selective nucleation occurs via a thin film reaction between a patterned array of 20 rnm thick indium islands which act as heterogeneous nucleation sites on the amorphous silicon starting material. Crystal growth proceeds by lateral solid phase epitaxy from the nucleation sites, during the incubation time for random nucleation. The largest achievable grain size by SNSPE is thus approximately the product of the incubation time and the solid phase epitaxy rate. Electronic dopants, such as B, P, and Al, are found to enhance the solid phase epitaxy rate and affect the nucleation rate.

Improvement of Grain Size by Crystallization of Double-Layer Amorphous Silicon Films

1994 ◽  
Vol 345 ◽  
Author(s):  
Dae Gyu Moon ◽  
Jeong No Lee ◽  
Ho Bin Im ◽  
Byung Tae Ahn ◽  
Kee Soo Nam ◽  
...  
Keyword(s):  
Grain Size ◽  
Double Layer ◽  
Nucleation Rate ◽  
Incubation Time ◽  
Deposition Temperature ◽  
Solid Phase ◽  
Chemical Vapor ◽  
Double Layers ◽  
Nucleation Sites ◽  
Si Films

AbstractWe investigated the solid phase crystallization (SPC) behavior of 1000 Å amorphous Si (a- Si) films deposited by plasma enhanced chemical vapor deposition (PECVD) at various temperatures and were able to enhance the grain size of the crystallized polysilicon films using double layers of a-Si filns. The deposition temperature of monolayer a-Si films varied from 200 to 400 °C and the films were recrystallized at 600 °C in nitrogen. As the deposition temperature increased, the incubation time was decreased and both the nucleation rate and growth rate were increased. Especially, the nucleation rate strongly depended on the deposition temperature.Since the Si-SiO2 interface provides a large number of nucleation sites, it is desirable to suppress nucleation at the interface. As an idea we employed a structure with double layer a-Si films. The bottom a-Si layer deposited at lower temperature could suppress the nucleation at the Si-SiO2 interface while the top a-Si layer deposited at higher temperature could nucleate with a smaller number of nucleation sites. The incubation time and transformation behavior were determined by the deposition temperature of the top layer. As an example, the grain size of the double layer film deposited sequentially at 150 °C and 200 °C enhanced to 1.8 μm while that of the monolayer film deposited at 200 °C was 1.4 μm.

Grain size, Grain Uniformity, and (111) Texture Enhancement by Solid-phase Crystallization of F- and C-implanted SiGe Films

2000 ◽  
Vol 15 (7) ◽  
pp. 1630-1634 ◽  
Author(s):  
A. Rodríguez ◽  
J. Olivares ◽  
C. González ◽  
J. Sangrador ◽  
T. Rodríguez ◽  
...  
Keyword(s):  
Grain Size ◽  
Vapor Deposition ◽  
Solid Phase ◽  
Chemical Vapor ◽  
Solid Phase Crystallization ◽  
Grain Sizes ◽  
Pressure Chemical ◽  
Film Microstructure ◽  
Si Films ◽  
Size Dispersion

The crystallization kinetics and film microstructure of poly-SiGe layers obtained by solid-phase crystallization of unimplanted and C- and F-implanted 100-nm-thick amorphous SiGe films deposited by low-pressure chemical vapor deposition on thermally oxidized Si wafers were studied. After crystallization, the F- and C-implanted SiGe films showed larger grain sizes, both in-plane and perpendicular to the surface of the sample, than the unimplanted SiGe films. Also, the (111) texture was strongly enhanced when compared to the unimplanted SiGe or Si films. The crystallized F-implanted SiGe samples showed the dendrite-shaped grains characteristic of solid-phase crystallized pure Si. The structure of the unimplanted SiGe and C-implanted SiGe samples consisted of a mixture of grains with well-defined contour and a small number of quasi-dendritic grains. These samples also showed a very low grain-size dispersion.

Solid Phase Crystallization of LPCVD Amorphous Si Films by Nucleation Interface Control

1996 ◽  
Vol 448 ◽  
Author(s):  
Eui-Hoon Hwang ◽  
Jae-Sang Ro
Keyword(s):  
Grain Size ◽  
Incubation Time ◽  
Solid Phase ◽  
Composite Films ◽  
Deposition Condition ◽  
Solid Phase Crystallization ◽  
Interface Control ◽  
Amorphous Si ◽  
Si Films ◽  
Deposition Conditions

AbstractA novel method for the fabrication of poly-Si films with a large grain size is reported using solid phase crystallization (SPC) of LPCVD amorphous Si films by nucleation interface control. The reference films used in this study were 1000 Ǻ -thick a-Si films deposited at 500°C at a total pressure of 0.35 Torr using Si2H6/He. Since the deposition condition changes the incubation time, i.e. nucleation rate, and since nucleation occurs dominantly at a-Si/SiO2 interface, we devised the following deposition techniques for the first time in order to obtain the larger gain size. A very thin a-Si layer (~ 50 Ǻ) with the deposition conditions having long incubation time is grown first and then the reference films (~ 950 Ǻ) are grown successively. Various composite films with different combinations were tested. The crystallization kinetics of composite films was observed to be determined by the deposition conditions of a thin a-Si layer at the a-Si/SiO2 interface. Nucleation interface was also observed to be modified by interrupted gas supply resulting in the enhancement of the grain size.

Thin-Film Transistors Fabricated With Poly-Si Films Crystallized by Microwave Annealing

1998 ◽  
Vol 508 ◽  
Author(s):  
YongWoo Choi ◽  
JeongNo Lee ◽  
TaeWoong Jang ◽  
ByungTae Ahn
Keyword(s):  
Thin Film ◽  
Grain Size ◽  
Thin Film Transistors ◽  
Solid Phase ◽  
Low Cost ◽  
Solid Phase Crystallization ◽  
Furnace Annealing ◽  
Microwave Annealing ◽  
Si Films ◽  
Better Than

AbstractSolid phase crystallization has the advantages of low cost and excellent uniformity but the crystallization temperature is too high to use glass as a substrate. Using microwave annealing, we crystallized a-Si films at 550 °C within 3 h, which is much shorter than the annealing time at 600 °C of furnace annealing. We fabricated TFTs with poly-Si films crystallized by microwave annealing at low temperature and obtained the characteristics slightly better than or at least comparable to the TFTs by furnace annealing in spite of smaller grain size. This may be due to the improvement of surface roughness of poly-Si film. The poly-Si TFTs with PECVD a-Si film showed better characteristics than the TFTs with LPCVD a-Si film because of larger grain size and smoother Si/SiO2 interface.

Controlled Grain Size and Location in GE Thin Films on Silicon Dioxide by Low Temperature Selective Solid Phase Crystallization

1995 ◽  
Vol 403 ◽  
Author(s):  
C. M. Yang ◽  
Harry A. Atwater
Keyword(s):  
Grain Size ◽  
Silicon Dioxide ◽  
Solid Phase ◽  
Crystal Nucleation ◽  
Solid Phase Crystallization ◽  
Grain Sizes ◽  
Amorphous Silicon Dioxide ◽  
Nucleation Sites ◽  
Phase Crystal ◽  
Metal Islands

AbstractSelective solid phase crystallization for control of grain size and location in polycrystalline thin Ge films on amorphous silicon dioxide substrates is described. The approach consists of selective solid phase crystal nucleation via an alloy reaction at predefined nucleation sites, which consist of metal islands deposited on top of the amorphous Ge film, followed by lateral solid phase epitaxial growth. Grain sizes as large as 30 μm have been achieved in 50 nm thick Ge films at temperatures less than 475 °C.

Fabrication of Polycrystalline Si Thin Film for Solar Cells

1996 ◽  
Vol 452 ◽  
Author(s):  
M. Tanaka ◽  
S. Tsuge ◽  
S. Kiyama ◽  
S. Tsuda ◽  
S. Nakano
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Crystal Growth ◽  
Conversion Efficiency ◽  
Solid Phase ◽  
Low Cost ◽  
Back Surface ◽  
Nucleation Layer ◽  
Surface Reflection ◽  
Si Thin Film

AbstractThe a-Si/poly-Si thin film tandem solar cell is a promising candidate for low-cost solar cells. We have conducted R&D on poly-Si thin film using the Solid Phase Crystallization (SPC) method from amorphous silicon (a-Si). To improve the film quality of SPC poly-Si, we have developed a new SPC method called the partial doping method. This method features two stacked starting a-Si layers, a P-doped layer and a non-doped layer. Nucleation occurs in the P-doped layer, and the non-doped layer is the crystal growth layer. For the nucleation layer, we developed a Si film with a unique structure, which features relatively large crystallites (-1000A) embedded in a matrix of amorphous tissue. By combining these technologies, a conversion efficiency of 9.2% was obtained for poly-Si thin-film solar cells. For further improvement in the conversion efficiency, based on the concept of “independent control of nucleation and crystal growth”, it is necessary to combine the best fabrication methods for each layer. A high conversion efficiency of more than 12% was found possible by using the CVD method and a new back surface reflection structure.

Lateral Solid Phase Epitaxy of Amorphous Si Films under Ultrahigh Pressure

1992 ◽  
Author(s):  
H. Ishiwara ◽  
H. Wakabayashi ◽  
K. Miyazaki ◽  
K. Fukao ◽  
A. Sawaoka
Keyword(s):  
Solid Phase ◽  
Ultrahigh Pressure ◽  
Solid Phase Epitaxy ◽  
Amorphous Si ◽  
Si Films

Boron Doping Effects in Lateral Solid Phase Epitaxy of Amorphous Si Films

1985 ◽  
Vol 24 (Part 2, No. 7) ◽  
pp. L513-L515 ◽  
Author(s):  
Hiroshi Ishiwara ◽  
Akihiro Tamba ◽  
Hiroshi Yamamoto ◽  
Seijiro Furukawa
Keyword(s):  
Solid Phase ◽  
Boron Doping ◽  
Solid Phase Epitaxy ◽  
Doping Effects ◽  
Amorphous Si ◽  
Si Films

Polycrystalline Silicon Films Formed by Solid-Phase Crystallization of Amorphous Silicon: the Substrate Effects on Crystallization Kinetics and Mechanism

1996 ◽  
Vol 424 ◽  
Author(s):  
Y.-H. Song ◽  
S.-Y. Kang ◽  
K. I. Cho ◽  
H. J. Yoo ◽  
J. H. Kim ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Solid Phase ◽  
Chemical Vapor ◽  
Solid Phase Crystallization ◽  
Substrate Effects ◽  
Random Nucleation ◽  
Pressure Chemical ◽  
Si Films ◽  
Polycrystalline Silicon Films ◽  
Induced Crystallization

AbstractThe substrate effects on the solid-phase crystallization of amorphous silicon (a-Si) have been extensively investigated. The a-Si films were prepared on two kinds of substrates, a thermally oxidized Si wafer (SiO2/Si) and a quartz, by low-pressure chemical vapor deposition (LPCVD) using Si2H6 gas at 470 °C and annealed at 600 °C in an N2 ambient for crystallization. The analysis using XRD and Raman scattering shows that crystalline nuclei are faster formed on the SiO2/Si than on the quartz, and the time needed for the complete crystallization of a-Si films on the SiO2/Si is greatly reduced to 8 h from ˜15 h on the quartz. In this study, it was first observed that crystallization in the a-Si deposited on the SiO2/Si starts from the interface between the a-Si film and the thermal oxide of the substrate, called interface-induced crystallization, while random nucleation process dominates on the quartz. The very smooth surface of the SiO2/Si substrate is responsible for the observed interface-induced crystallization of a-Si films.

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