Method and apparatus for characterizing microelectromechanical devices on wafers
First Claim
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1. A method of evaluating a quality of a plurality of microelectromechanical devices on a wafer, each microelectromechanical device having a reflective and deflectable plate attached to a deformable hinge that is held on the wafer;
- the method comprising;
measuring a distribution of a resonant frequency of the microelectromechanical device comprising;
illuminating a number of the reflective and deflectable plates with a light beam;
applying an AC voltage to the number of plates such that the plates oscillate in vicinity of their equilibrium states; and
sweeping the frequency of the AC voltage, and measuring the frequency response of the reflected light beam from the illuminated plates; and
evaluating and displaying said quality of a uniformity of the microelectromechanical device on the wafer based on the measured distribution of the resonant frequency.
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Abstract
The invention provides a method and apparatus for evaluating the quality of microelectromechanical devices having deformable and deflectable members using resonation techniques. Specifically, product quality characterized in terms of uniformity of the deformable and deflectable elements is inspected with an optical resonance mapping mechanism on a wafer-level.
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Citations
32 Claims
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1. A method of evaluating a quality of a plurality of microelectromechanical devices on a wafer, each microelectromechanical device having a reflective and deflectable plate attached to a deformable hinge that is held on the wafer;
- the method comprising;
measuring a distribution of a resonant frequency of the microelectromechanical device comprising; illuminating a number of the reflective and deflectable plates with a light beam; applying an AC voltage to the number of plates such that the plates oscillate in vicinity of their equilibrium states; and sweeping the frequency of the AC voltage, and measuring the frequency response of the reflected light beam from the illuminated plates; and evaluating and displaying said quality of a uniformity of the microelectromechanical device on the wafer based on the measured distribution of the resonant frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
- the method comprising;
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26. A method of evaluating a quality of a plurality of microelectromechanical devices on a wafer, each microelectromechanical device having a reflective and deflectable plate attached, the method comprising:
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applying an AC voltage in the absence of a DC voltage to a plurality of the plates to cause each of the plurality of plates to resonate in the vicinity of an equilibrium state; detecting a resonate frequency of the plate; and determining and displaying the quality of themicroelectromechanical device based upon the detected resonance frequency. - View Dependent Claims (27)
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28. A method of evaluating a quality of a plurality of microelectromechanical devices on a wafer, each microelectromechanical device having a reflective and deflectable plate attached, the method comprising:
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moving a plurality of plates of the microelectromechanical devices to a particular state with a DC voltage; applying an AC voltage to the plurality of plates to cause each of the plurality of plates to resonate in the vicinity of an equilibrium position of the particular state; detecting a resonate frequency of the plate; and determining and displaying the quality of the microelectromechanical device based upon the detected resonance frequency; wherein in the particular position, the plate has an angle to a substrate on which the plates are formed; and
wherein the angle is 14°
degrees or more. - View Dependent Claims (29, 30, 31, 32)
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Specification