Lpcvd Polycrystalline Silicon Thin Films: The Evolution of Structure, Texture and Stress

ABSTRACTAn investigation of undoped LPCVD polycrystalline silicon films deposited at temperatures ranging from 605 to 700 C and silane pressures from 300 to 550 mTorr revealed large variations in stress with processing conditions and a correlation between stress and texture. TEM and HRTEM analysis show that morphology differences also exist. At lower temperatures (≈605 C) and higher pressures (≈400 mTorr), the films appear to deposit in an amorphous state and crystallize during the deposition to form microstructures characterized by equi-axed grains, tensile residual stress, and a texture with {110} and {11/} (/=2 or 3) components. Higher temperatures (between 620 and 650 C) produce films that nucleate at the Si02 interface, creating a {110} oriented columnar microstructure. At 700 C, the grains are still columnar, but the dominant texture is {100}. Films deposited at temperatures greater than 620 C exhibit compressive stress, and some contain regions of hexagonal silicon. This paper proposes possible causes of the varying stresses, textures, and microstructures in the films.

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Hydrogen Dilution Effect on the Crystallinity of Silicon Films Grow by Hot Wire Cell Method

MRS Proceedings ◽

10.1557/proc-557-531 ◽

1999 ◽

Vol 557 ◽

Cited By ~ 6

Author(s):

M. Ichikawa ◽

J. Takeshita ◽

A. Yamada ◽

M. Konagai

Keyword(s):

Thin Films ◽

Growth Rate ◽

Polycrystalline Silicon ◽

High Growth ◽

Silicon Films ◽

Hot Wire ◽

Cell Method ◽

Silicon Thin Films ◽

Hydrogen Dilution ◽

Polycrystalline Silicon Films

AbstractA new process, the Hot Wire Cell method, was developed and successfully used to grow polycrystalline silicon thin films at a low temperature and high growth rate. In the Hot Wire Cell method, reactant gases are decomposed as a result of reacting with a heated tungsten filament placed near to a substrate and polycrystalline silicon films can be deposited at a growth rate of 1.2nm/s without hydrogen dilution and 0.9nm/s with the use hydrogen dilution. The film crystallinity changed from amorphous to polycrystalline due to the addition of hydrogen, thus hydrogen dilution was effective for improving film crystallinity. Furthermore, we obtained (220) oriented polycrystalline silicon thin films with a 90% crystal fraction by the use of hydrogen dilution. These results showed that the Hot Wire Cell method is promising for the deposition of device-grade polycrystalline silicon films for photovoltaic applications.

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Redistribution of Ion Implanted Hydrogen in Polycrystalline Silicon Thin Films

MRS Proceedings ◽

10.1557/proc-59-493 ◽

1985 ◽

Vol 59 ◽

Cited By ~ 1

Author(s):

Ronald N. Legge ◽

James F. Brown

Keyword(s):

Thin Films ◽

Hall Mobility ◽

Low Temperatures ◽

Polycrystalline Silicon ◽

Silicon Films ◽

Spreading Resistance ◽

Silicon Thin Films ◽

Polycrystalline Silicon Films ◽

Diffusion Of Hydrogen ◽

Ion Implanted

ABSTRACTThe effect of implanted hydrogen on the resistivity of polycrystalline silicon films has been investigated. The observed reduction in resistivity due to hydrogen is most pronounced for lightly doped films, and is accentuated by a 450°C anneal. An increase in Hall mobility is also observed. The pre-implant resistivity is completely recovered by annealling at 600°C. Diffusion of hydrogen at low temperatures is monitored by local resistivity changes detected with spreading resistance measurements.

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Polycrystalline silicon thin films by aluminum induced crystallization of amorphous silicon

Applied Surface Science ◽

10.1016/j.apsusc.2012.09.019 ◽

2013 ◽

Vol 264 ◽

pp. 11-16 ◽

Cited By ~ 19

Author(s):

T. Wang ◽

H. Yan ◽

M. Zhang ◽

X. Song ◽

Q. Pan ◽

...

Keyword(s):

Thin Films ◽

Amorphous Silicon ◽

Polycrystalline Silicon ◽

Silicon Thin Films ◽

Induced Crystallization ◽

Aluminum Induced Crystallization

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The Materials Science of “Permeable Polysilicon” Thin Films

MRS Proceedings ◽

10.1557/proc-687-b7.3 ◽

2001 ◽

Vol 687 ◽

Author(s):

George M Dougherty ◽

Timothy Sands ◽

Albert P. Pisano

Keyword(s):

Thin Films ◽

Residual Stress ◽

Materials Science ◽

Single Step ◽

Process Window ◽

Silicon Thin Films ◽

Growth Regime ◽

Deposition Parameters ◽

Simple Kinetic Model ◽

The Relationship

AbstractPolycrystalline silicon thin films that are permeable to fluids, known as permeable polysilicon, have been reported by several researchers. Such films have great potential for the fabrication of difficult to make MEMS structures, but their use has been hampered by poor process repeatability and a lack of physical understanding of the origin of film permeability and how to control it. We have completed a methodical study of the relationship between process, microstructure, and properties for permeable polysilicon thin films. As a result, we have determined that the film permeability is caused by the presence of nanoscale pores, ranging from 10-50 nm in size, that form spontaneously during LPCVD deposition within a narrow process window. The unusual microstructure within this process window corresponds to the transition between a semicrystalline growth regime, exhibiting tensile residual stress, and a columnar growth regime exhibiting compressive residual stress. A simple kinetic model is proposed to explain the unusual morphology within this transition regime. It is determined that measurements of the film residual stress can be used to tune the deposition parameters to repeatably produce permeable films for applications. The result is a convenient, single-step process that enables the elegant fabrication of many previously challenging structures.

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