Semiconductor device manufacturing: process – Packaging or treatment of packaged semiconductor – With vibration step
Reexamination Certificate
1999-09-07
2001-05-01
Niebling, John F. (Department: 2812)
Semiconductor device manufacturing: process
Packaging or treatment of packaged semiconductor
With vibration step
C438S127000
Reexamination Certificate
active
06225145
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing a vacuum micro-structure to be used for elements of microelectromechanical system (MEMS) or the like that operate in vacuum, and more particularly, to a method of fabricating a MEMS structure by connecting the vacuum micro-structure with external elements.
2. Description of Related Art
An example of the related art is a method of encapsulating a microelectronic device in a vacuum chamber through a surface process, which is proposed by Boysel et al. (U.S. Pat. No. 5,354,714, Oct. 11, 1994, “Method of forming a vacuum micro-chamber for encapsulating a microelectronic device”). This method includes the steps of preparing a device on a substrate, applying an organic agent such as photoresist on the surface of the device to define a pattern, depositing a metal film, forming an open window in the metal film coated on the photoresist in order to remove the photoresist confined inside the metal film, and decomposing the photoresist to be removed with a solvent or the like. According to the method, the open window is hermetically sealed by a metal film redeposition step performed in a vacuum, thereby manufacturing a vacuum micro-element. This method, however, has a problem in that it is inapplicable to a large-sized vacuum structure because the thickness of the thin film used as a sealing material is limited to several micrometers and the vacuum pressure may transform the vacuum structure.
Another method involves use of a small-sized vacuum can but is disadvantageous in that mass productivity is poor because packaging is performed in the unit of element.
Generally, an angular velocity sensor with a vacuum microstructure that is manufactured by processing a silicon wafer in the semiconductor process includes a comb-like drive and detection electrode and a spring beam which are spatially floating over the substrate. When driving the angular velocity sensor at high frequency, however, the internal space of the structure must be kept in vacuum.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a method of fabricating a vacuum micro-structure that substantially obviates one or more of the limitations and disadvantages of the related art.
An object of the present invention is to provide a method of fabricating a vacuum micro-structure which is to prepare a high vacuum micro-space as well as vacuum structure floating in a micro-space such that the vacuum micro-structure is easy to use together with normal chips by improving the related art methods for encapsulating driver chips, such as performing deposition or using a small-sized vacuum can, and enabling manufacture of the vacuum micro-structure through a process performed in the unit of wafer.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure as illustrated in the written description and claims hereof, as well as the appended drawings.
To achieve these and other advantages, and in accordance with the purpose of the present invention as embodied and broadly described, a method of fabricating a vacuum micro-structure, which is used for an element operating in a vacuum, includes the steps of: (1) entirely etching an epitaxial layer of a silicon substrate having an SOI structure including an upper silicon epitaxial layer, an interlevel insulating layer and a lower silicon bulk layer to form two electrode structures and a floating vibratory structure, and encapsulating them with a vacuum sealing substrate in a vacuum; and (2) etching the silicon substrate having the SOI stricture from the back side to the interlevel insulating layer to open the electrode structures, and forming a metal electrode. According to the present invention, it is possible to mount the vacuum micro-structure formed on the surface of a wafer in a high vacuum by anodic bonding and perform a batch processing and packaging in the unit of wafer such as IC chip.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
REFERENCES:
patent: 5354714 (1994-10-01), Boysel
patent: 5592007 (1997-01-01), Leedy
patent: 5834334 (1998-11-01), Leedy
patent: 6020257 (2000-02-01), Leedy
Choi Chang Auck
Jang Won Ick
Kim Dae Yong
Lee Jong Hyun
Antonelli Terry Stout & Kraus LLP
Electronics and Telecommunications Research Institute
Gurley Lynne A.
Niebling John F.
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