Semiconductor device manufacturing: process – Formation of semiconductive active region on any substrate – Amorphous semiconductor
Reexamination Certificate
2001-02-28
2003-10-21
Kielin, Erik (Department: 2813)
Semiconductor device manufacturing: process
Formation of semiconductive active region on any substrate
Amorphous semiconductor
C438S500000, C117S043000, C117S046000, C117S050000
Reexamination Certificate
active
06635555
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to semiconductor technology and more particularly to the method of forming polycrystalline silicon regions within an amorphous silicon film.
Polycrystalline silicon is formed by crystallizing amorphous silicon films. One method of crystallizing amorphous silicon films is Excimer Laser Annealing (ELA). Conventional ELA processes form polycrystalline films having a random polycrystalline structure. Random, as used here, means that no single crystal orientation is dominant and that polycrystalline structures consist of a mixture of crystallographic orientations in silicon. These crystallographic orientations in silicon are commonly denoted as <
111
>, <
110
>, and <
100
>, along with their respective corollaries, as is well known in the art. Control of crystallographic orientation is generally desirable because the electrical characteristics of a polycrystalline silicon film depend upon the crystallographic orientation of the film. In addition, the uniformity of the electrical characteristics will improve if the majority of the film has a controllable texture.
ELA, as well as many other annealing methods, has not provided a means to control these microstructural characteristics and achieve a predictable and repeatable preferential crystal orientation and film texture within an annealed film. It would be desirable to have a method of producing a more uniform crystallographic orientation within a polycrystalline silicon film. It would also be desirable to be able to select a desired crystallographic orientation.
SUMMARY OF THE INVENTION
Accordingly, a method of forming a polycrystalline silicon film with a desired predominant crystal orientation is provided. The method of forming polycrystalline films on a substrate comprises the steps of: providing a substrate, depositing an amorphous silicon film on the substrate, annealing the substrate to produce a polycrytstalline film with the desired predominant crystal orientation, preferably a <
100
> crystal orientation, and polishing the polycrystalline film to prepare the film for further processing.
The substrate can be any material which is compatible with the deposition of amorphous silicon and excimer laser annealing. For display applications, the substrate is preferably a transparent substrate such as quartz, glass or plastic.
To achieve a good quality film that is predominantly <
100
> crystal orientation, the step of depositing the amorphous film should deposit to a thickness of at least approximately 100 nm.
The step of annealing preferably uses a laterally seeded excimer laser annealing process. The step of polishing can be accomplished by any means that would not significantly modify the crystal orientation of the film, including by chemical mechanical polishing. For some applications a final film thickness of less than 60 nm is desirable.
The method of the present invention, produces a prepared substrate comprising a polycrystalline film, which has a predominantly <
100
> crystal orientation, overlying a carrier substrate. The final film is preferably less than 60 nm thick. For display applications, as discussed above, the carrier substrate is preferably a transparent material such as quartz, glass or plastic.
REFERENCES:
patent: 5943560 (1999-08-01), Chang et al.
patent: 6190949 (2001-02-01), Noguchi et al.
patent: 6274888 (2001-08-01), Suzuki et al.
patent: 6426246 (2002-07-01), Chang et al.
patent: WO97/45827 (1997-12-01), None
Sposili et al. “Sequential lateral solidification of thin silicon films on SiO2” Applied Physics Letters 69(19) Nov. 4, 1996, pp. 2864-2866.*
Toet, et al. “Laser crystallization and structural characterization of hydrogenated amorphous silicon thin films” Journal of Applied Physics 85(11), Jun. 1, 1999, pp. 7914-7918.*
Fork, et al. “Capillary waves in pulsed excimer laser crystallized amorphous silicon” Applied Physics Letters 68(15), Apr. 8, 1996, pp. 2138-2140.*
Article entitled, “Controlled Super-Lateral Growth of Si Films for Microstructural Manipulation and Optimization”, by J.S. Im, M.A. Crowder, R. S. Sposili, J. P. Leonard, H. J. Kim, J. H. Yoon, V. V. Gupta, H. Jin Song and H. S. Cho, published in Phys. Stat. Sol. (a) 166, 1998, pp. 603-617.
Article entitled, “Phase Transformation Mechanisms Involved in Excimer Laser Crystallization of Amorphous Silicon Films”, by J. S. Im, H. J. Kim and M. O. Thompson, published in Apply. Phys. Letter 63 (14), Oct. 4, 1993, pp. 1969-1971.
Article entitled, “Sequential Lateral Solidification of Thin Silicon Films on SiO2”, by R. S. Sposili and J. S. Im, published in Appl. Phys. Lett. 69 (19) Nov. 4, 1996, pp. 2864-2866.
Article entitle, “Grain populations in laser-crystallized silicon thin films on glass substrates,” by M. Nerding et al. published in Thin Solid Films, vol. 383, Issues 1-2, Feb. 15, 2001, pp. 110-112.
Kielin Erik
Krieger Scott C.
Rabdau Matthew D.
Ripma David C.
Sharp Laboratories of America Inc.
LandOfFree
Method of controlling crystallographic orientation in... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of controlling crystallographic orientation in..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of controlling crystallographic orientation in... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3170281