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US 2003/0196489 A1Published application
Method of trimming micro-machined electromechanical sensors (MEMS) devices
AssigneeHoneywell International Inc.
InventorPaul W. Dwyer
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AssigneeHoneywell International Inc.
InventorPaul W. Dwyer
Estimating the term…
A method for delicately adjusting an orientation of features in completed micro-machined electromechanical sensor (MEMS) devices after initial formation and installation within the device packaging to trim one or more performance parameters of interest, including modulation, bias and other dynamic behaviors of the MEMS devices.
A method of compensating MEMS devices, the method comprising:
A compensation method for MEMS devices, the method comprising:
A method of manufacturing an acceleration sensor, the method comprising:
A method of manufacturing MEMS devices, the method comprising:
A micro-machined electromechanical sensor (MEMS) device, comprising:
A micro-machined electromechanical sensor (MEMS) device, comprising:
A micro-machined electromechanical acceleration sensor, comprising:
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
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Subject matter not provided for in other groups of this subclass: testing
Mechanical properties: treatments for controlling internal stress or strain in MEMS structures
Manufacturing logistics: process control; Yield prediction
Controlling internal stress of deposited layers: by adding further layers of materials having complementary strains, i.e. compressive or tensile…
Term end not estimated
The present invention relates generally to methods for manufacturing micromachined electromechanical sensor (MEMS) devices, and in particular to methods for compensating cumulative variations during processing.
The manufacture of MEMS devices, such as accelerometers or rate sensors, is generally well-known and includes many individual processes. Each of the individual processes is a source of variation. The variations of the individual processes accumulate in significant performance differences between different devices manufactured using the same processes in the same way.
One means of coping with this cumulative variation is to control each of the processes in a serial manner to the degree necessary to maintain the cumulative variation within predetermined design parameters. Such process control can, however, be extremely time consuming and costly.
The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:
FIG. 1 illustrates one embodiment of the method of the invention;
FIG. 2 illustrates a second embodiment of the method of the invention;
In the Figures, like numerals indicate like elements.
The present invention is a compensation method that provides for delicately adjusting an orientation of features in completed and operational MEMS devices, which may or may not already have silicon cover plates applied to protect mechanism integrity. The method of the invention permits the trimming of modulation, bias and other dynamic behaviors of MEMS devices after initial formation and installation within the device packaging.
The compensation method of the present invention exploits the ability of film stresses to change the shape of the MEMS device. Film stresses are created in the MEMS device by growing a film of material on the MEMS silicon substrate having a different thermal expansion coefficient from the MEMS silicon substrate. Such a film, grown on the MEMS substrate at elevated temperature, is highly stressed by the difference in expansion coefficient. After the film is grown on the substrate, laser radiation is used to selectively remove a portion of the stressed film, such that the remaining stressed film material upsets the balance of stresses on a member of the MEMS device and causes it to take on a different shape. The extent to which the balance of stresses is upset depends on the amount of material grown, the amount of material removed, the location from which the material is removed, and the sensitivity of the particular MEMS design to the material removal.