Chemistry: electrical and wave energy – Processes and products – Coating – forming or etching by sputtering
Reexamination Certificate
2000-03-03
2001-04-03
Huff, Mark F. (Department: 1753)
Chemistry: electrical and wave energy
Processes and products
Coating, forming or etching by sputtering
C204S192120, C204S192110, C204S298290, C204S298110, C204S298040, C204S192150, C204S298230
Reexamination Certificate
active
06210540
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
REFERENCE TO MICROFICHE APPENDIX
Not applicable.
FIELD OF THE INVENTION
The present invention is generally related to thin film deposition techniques, and more particularly to a method and apparatus for depositing a thin film on a surface that is essentially vertical to a major plane of a substrate.
BACKGROUND OF THE INVENTION
Thin film processing is used in many industrial applications, such as semiconductor fabrication, optical component fabrication, and micro-electro-mechanical systems (“MEMS”). In many, if not most, applications, a thin film layer is formed on a major surface of a substrate, such as the polished surface of a silicon wafer or the surface of a glass blank. However, some devices and fabrication process need to deposit a thin film on a surface that is vertical to the major surface of the substrate. For example, a structure of a MEMS device might be formed by deep reactive ion etching (“DRIE”), and it might be desirable to deposit a layer on a vertical surface or surfaces. Unfortunately, most deposition processes are not suited for forming such a layer. In particular, conventional processes tend to build up material proximate to the major surface while not depositing as much material distal from the major surface. This can cause a rough or uneven surface, affecting the performance of the deposited layer.
Thus it is desirable to provide a method and apparatus for forming an even layer of thin film material on a vertical surface of a structure formed on a substrate.
SUMMARY OF THE INVENTION
The present invention provides a method and apparatus for depositing thin film layers on vertical surfaces of structures fabricated or attached to a substrate by masking a central portion of a material source and rotating the workpiece with respect to the material source. In a particular embodiment, the material source is a sputtering target. A mask is placed over a central portion of the sputtering target to limit the material flux from the target to a side lobe or lobes. The aperture between the mask and the edge of the target is chosen according to the distance of the workpiece from the target and depth of the vertical surface, which in a specific embodiment is about 70-75 microns with a set-back of about 200-250 microns from a facing wall of the MEMS structure. The sputtering is done at a low angle of incidence compared with conventional sputtering onto the major surface. The low angle of incidence results in a longer mean free path between the target and the device, thus the sputtering pressure is reduced. In a particular embodiment, the mean free path is increased from about 5-7 cm for sputtering onto a major surface to about 20-30 cm for sputtering onto a vertical surface, and the chamber pressure is reduced from nominally 1-3 mT to about 10
−4
T.
REFERENCES:
patent: 3856654 (1974-12-01), George
patent: 3904503 (1975-09-01), Hanfmann
patent: 4591418 (1986-05-01), Snyder
patent: 4851095 (1989-07-01), Scobey et al.
patent: 5415753 (1995-05-01), Hurwitt et al.
patent: 5618388 (1997-04-01), Seeser et al.
Chacko Davis Daborah
Hewett Scott W.
Huff Mark F.
Optical Coating Laboratory, Inc.
LandOfFree
Method and apparatus for depositing thin films on vertical... 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 and apparatus for depositing thin films on vertical..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for depositing thin films on vertical... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2544800