Semiconductor device manufacturing: process – Making device or circuit responsive to nonelectrical signal – Physical stress responsive
Reexamination Certificate
2000-01-14
2001-03-06
Smith, Matthew (Department: 2825)
Semiconductor device manufacturing: process
Making device or circuit responsive to nonelectrical signal
Physical stress responsive
C438S048000, C438S049000, C257S254000, C257S414000, C257S415000, C257S416000, C257S417000
Reexamination Certificate
active
06197610
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates generally to semiconductor processing, and in one embodiment, to a method for making small gaps for micro electromechanical systems (MEMS) devices, or small electrical/mechanical devices.
Many different integrated circuit devices sometimes require one or more small gaps placed within the circuit. For example, MEMS devices and other small electrical/mechanical devices may incorporate a gap in the device to allow the device to respond to mechanical stimuli. One common MEMS device is a sensor, such as an accelerometer, for detecting external force, acceleration or the like by electrostatically or magnetically floating a portion of the device. The floating portion can then move responsive to the acceleration and the device can detect the movement accordingly. In some cases, the device has a micro spherical body referred to as a core, and a surrounding portion referred to as a shell. Electrodes in the shell serve not only to levitate the core by generating an electric or magnetic field, but to detect movement of the core within the shell by measuring changes in capacitance and/or direct contact of the core to the shell.
Conventionally, the core and the shell are separately made and assembled. Therefore, no appropriate method for making a MEMS device where the core and shell are precisely arranged in close vicinity with each other has been known.
In the field of semiconductor device production, many methods and techniques are known for making micro chips and forming microscopic circuit patterns in multiple-layers. These methods include, for example, lithography, etching, chemical vapor deposition (CVD), electron beam exposure printing or the like. However, these methods can make plane boards or chips, but cannot make a micro spherical body and micro electrodes which are disposed in close vicinity to the micro spherical body.
In U.S. Pat. No. 5,955,776, assigned to the same assignee as the present application and hereby incorporated by reference as if reproduced in its entirety, a method and system for manufacturing spherical-shaped semiconductor integrated circuits is disclosed. A manufacturing process disclosed in the aforementioned patent is used to create and process semiconductor spheres, such as may be used for spherical-shaped semiconductor integrated circuits.
SUMMARY OF THE INVENTION
The present invention provides a method for making small gaps in MEMS devices. In one embodiment, the MEMS device is first made with a sacrificial layer where the gap is to reside. The device can then be assembled, including forming a protective coat surrounding the device. Once the protective coat is formed, small holes in the protective coat can be made to expose the sacrificial layer to an external environment. After the small holes have been made, an etchant can then be applied through the holes to remove the sacrificial layer.
In some embodiments, the holes are formed using laser ablation.
In some embodiments, one or more solder bumps are assembled to the device and a substrate before the sacrificial layer is removed.
In some embodiments, the protective coat is also formed around the solder bumps and around the substrate.
In some embodiments, the etchant is a dry etchant that can flow easily through the holes.
In some embodiments, the device is built around a spherical shaped substrate. The device can also be built around a flat substrate.
REFERENCES:
patent: Re. 31473 (1983-12-01), Kilby et al.
patent: 5278097 (1994-01-01), Hotchkiss et al.
patent: 5365671 (1994-11-01), Yaniger
patent: 5431127 (1995-07-01), Stevens et al.
patent: 5457333 (1995-10-01), Fukui
patent: 5462639 (1995-10-01), Matthews et al.
patent: 5466301 (1995-11-01), Hammerbacher et al.
patent: 5726480 (1998-03-01), Pister
patent: 5786621 (1998-07-01), Saif et al.
patent: 5845730 (1998-12-01), Thuen et al.
patent: 5955776 (1999-09-01), Ishikawa
patent: 6032531 (2000-03-01), Roszhart
patent: 6077388 (2000-06-01), Freeman
patent: 2-119241 (1988-10-01), None
Ball Semiconductor Inc.
Haynes and Boone LLP
Lee Granvill
Smith Matthew
LandOfFree
Method of making small gaps for small electrical/mechanical... 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 making small gaps for small electrical/mechanical..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of making small gaps for small electrical/mechanical... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2524475