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CN-121990520-A - Method for manufacturing a mirror device of a microelectromechanical system, manufacturing apparatus, mirror device group and wafer

CN121990520ACN 121990520 ACN121990520 ACN 121990520ACN-121990520-A

Abstract

The present disclosure relates to a method, apparatus, mirror device set, and wafer for fabricating a micro-electromechanical system mirror device. According to an embodiment, a method for fabricating a microelectromechanical mirror device is provided. The mirror portion of the mirror device is rotatable about a first axis having an associated first resonant frequency and a second axis having an associated second resonant frequency and different from the first axis. The method comprises estimating a deviation of a first geometry parameter of the mirror device from a reference value, and adjusting a manufacturing step of the mirror device to modify a second geometry parameter of the mirror device, wherein the second geometry parameter is different from the first geometry parameter such that a change in a frequency ratio between the first resonant frequency and the second resonant frequency caused by the deviation of the first geometry parameter and the modification of the second geometry parameter is below a predefined threshold.

Inventors

  • DIRK MEINHOLD
  • S. G. Albert
  • A. Brockmaire
  • M. Baynshabi

Assignees

  • 英飞凌科技股份有限公司

Dates

Publication Date
20260508
Application Date
20251030
Priority Date
20241105

Claims (14)

  1. 1. A method for manufacturing a microelectromechanical system mirror device (10; 61a;61 b), wherein a mirror portion of the mirror device (10; 61a;61 b) is rotatable about a first axis (12; 40) and a second axis (14; 46), the first axis (12; 40) having an associated first resonant frequency, the second axis (14; 46) being different from the first axis (12; 40) and having an associated second resonant frequency, the method comprising: estimating a deviation of a first geometry parameter (d 1, d 2) of the mirror device (10; 61A; 61B) from a reference value (61A; 61B), -Adjusting the manufacturing steps of the mirror device (10; 61a;61 b) to modify a second geometry parameter (w 1, w 2) of the mirror device (10; 61a;61 b), the second geometry parameter (w 1, w 2) being different from the first geometry parameter (d 1, d 2) such that the variation of the frequency ratio between the first and the second resonance frequency caused by the deviation of the first geometry parameter (d 1, d 2) and the modification of the second geometry parameter (w 1, w 2) is below a predefined threshold.
  2. 2. The method according to claim 1, further comprising determining the adjustment of the manufacturing step based on a model of the mirror device (10; 61a;61 b), the model of the mirror device (10; 61a;61 b) providing the variation of the frequency ratio according to the first geometry parameter (d 1, d 2) and the second geometry parameter (w 1, w 2).
  3. 3. Method according to claim 1 or 2, wherein the mirror device (10; 61a;61 b) is manufactured at a first location on a substrate, and wherein the reference value is a value of the first geometrical parameter (d 1, d 2) of a further mirror device (10; 61a;61 b), the further mirror device (10; 61a;61 b) being manufactured at a second location on the substrate, the second location being different from the first location.
  4. 4. A method according to any one of claims 1 to 3, wherein estimating the deviation of the first geometry parameter (d 1, d 2) comprises measuring a deviation of the first geometry parameter (d 1, d 2) of a further mirror device (10; 61a;61 b), the further mirror device (10; 61a;61 b) being manufactured using the same processing means before manufacturing the mirror device (10; 61a;61 b) and using the measured deviation as the estimated deviation.
  5. 5. A method according to any one of claims 1 to 3, wherein estimating the deviation of the first geometry parameter (d 1, d 2) comprises measuring the deviation of the first geometry parameter (d 1, d 2) of the mirror device (10; 61a;61 b) in a manufacturing stage prior to the manufacturing step.
  6. 6. The method according to any one of claims 1 to 5, wherein the first geometry parameter (d 1, d 2) comprises a layer thickness of a layer defining an inertial mass coupled to the mirror portion.
  7. 7. The method of any one of claims 1 to 6, wherein adjusting the manufacturing step comprises adjusting an exposure dose for photolithography.
  8. 8. The method of any of claims 1 to 7, wherein adjusting the manufacturing step comprises changing the geometry of a mask (82) for lithography.
  9. 9. The method according to any one of claims 1 to 8, wherein the second geometry parameter (w 1, w 2) defines one of a suspension of the mirror portion associated with at least one of the first axis (12; 40) or the second axis (14; 46), a gimbal structure of the mirror device (10; 61a;61 b), a width of an inertial mass portion of the mirror device (10; 61a;61 b), or a reinforcing structure of the mirror device (10; 61a;61 b).
  10. 10. The method according to any one of claims 1 to 9, wherein the predefined threshold is less than 1%.
  11. 11. A manufacturing apparatus (30), comprising: A processing chain (31), the processing chain (31) being configured to perform a plurality of processing steps for manufacturing a microelectromechanical system mirror device (10; 61A; 61B), wherein a mirror portion of the mirror device (10; 61A; 61B) is rotatable about a first axis (12; 40) and a second axis (14; 46), the first axis (12; 40) having an associated first resonant frequency, the second axis (14; 46) being different from the first axis (12; 40) and having an associated second resonant frequency, and A process control device (32), the process control device (32) being configured to estimate a deviation of a first geometry parameter (d 1, d 2) of the mirror device (10; 61A; 61B) from a reference value and to adjust a manufacturing step of the mirror device (10; 61A; 61B) to modify a second geometry parameter (w 1, w 2) of the mirror device (10; 61A; 61B), the second geometry parameter (w 1, w 2) being different from the first geometry parameter (d 1, d 2) such that the deviation of the first geometry parameter (d 1, d 2) and a change in a frequency ratio between the first resonant frequency and the second resonant frequency caused by the modification of the second geometry parameter (w 1, w 2) are below a predefined threshold.
  12. 12. The manufacturing apparatus (30) according to claim 11, the manufacturing apparatus (30) being configured to perform the method according to any one of claims 1 to 11.
  13. 13. A set of microelectromechanical system mirror devices (10; 61A; 61B) of the same type, wherein the mirror portion of each mirror device (10; 61A; 61B) in the set is rotatable about a respective first axis (12; 40) and a respective second axis (14; 46), the first axis (12; 40) having an associated first resonant frequency, the second axis (14; 46) being different from the first axis (12; 40) and having an associated second resonant frequency, the set comprising the first mirror device (10; 61A; 61B) and the second mirror device (10; 61A; 61B), Wherein a first geometry parameter (d 1, d 2) of the first mirror device (10; 61A; 61B) differs from the first geometry parameter (d 1, d 2) of the second mirror device (10; 61A; 61B) by a first difference, Wherein a second geometry parameter (w 1, w 2) of the first mirror device (10; 61A; 61B) differs from the second geometry parameter (w 1, w 2) of the second mirror device (10; 61A; 61B) by a second difference, Wherein a difference between a first ratio between the first resonant frequency and the second resonant frequency of the first mirror device (10; 61A; 61B) and a second ratio between the first resonant frequency and the second resonant frequency of the second mirror device (10; 61A; 61B) caused only by the first difference is higher than 1% and is compensated by the second difference to be lower than 1%.
  14. 14. A wafer (60) comprising a first microelectromechanical system mirror device (10; 61A; 61B) at a first position and a second microelectromechanical system mirror device (10; 61A; 61B) at a second position, wherein a mirror portion of each of the first and second mirror devices (10; 61A; 61B) is rotatable about a respective first axis (12; 40) and a respective second axis (14; 46), the first axis (12; 40) having an associated first resonant frequency, the second axis (14; 46) being different from the first axis (12; 40) and having an associated second resonant frequency, Wherein a first geometry parameter (d 1, d 2) of the first mirror device (10; 61A; 61B) differs from the first geometry parameter (d 1, d 2) of the second mirror device (10; 61A; 61B) by a first difference, Wherein a second geometry parameter (w 1, w 2) of the first mirror device (10; 61A; 61B) differs from the second geometry parameter (w 1, w 2) of the second mirror device (10; 61A; 61B) by a second difference, Wherein a difference between a first ratio between the first resonant frequency and the second resonant frequency of the first mirror device (10; 61A; 61B) and a second ratio between the first resonant frequency and the second resonant frequency of the second mirror device (10; 61A; 61B) caused only by the first difference is higher than 1% and is compensated by the second difference to be lower than 1%.

Description

Method for manufacturing a mirror device of a microelectromechanical system, manufacturing apparatus, mirror device group and wafer Technical Field The present application relates to a method for manufacturing a microelectromechanical system (MEMS) mirror device, a corresponding manufacturing apparatus, a corresponding set of mirror devices and a wafer comprising a plurality of mirror devices. Background A Laser Beam Scanner (LBS) is a device that scans a laser beam across regions by deflecting the laser beam using one or more adjustable mirrors. For example, such a laser beam scanner may be used in display applications in which a laser beam is scanned across a screen. One type of laser beam scanner is a two-axis resonant Lissajous (Lissajous) laser beam scanner. Here, the mirror may rotate about two axes, each axis having an associated resonant frequency. The axis with the higher resonance frequency is also called the fast axis, while the axis with the lower resonance frequency is called the slow axis. Fig. 1 shows a schematic view of a corresponding mirror device with a gimbal structure. Here, the mirror 11 is suspended so as to be rotatable about a first axis 12 in a frame 13. The frame 13 is suspended so as to be rotatable within the frame 15 about a second axis 14. In operation, the frame 15 is stationary. In the mirror device 10, the first axis 12 is generally associated with a higher resonant frequency than the second axis 14, since not only the mirror 11, but also the frame 13 and the axis 12 rotate together about the axis 14, i.e. there is a higher mass. However, the resonant frequency may also be affected by the design of the axes, such as their torsion spring constants. The mirror device 10 may be implemented as a microelectromechanical system (MEMS), for example by processing a silicon wafer accordingly with standard techniques for fabricating such MEMS, including photolithography, etching, layer deposition, etc. In addition to the elements schematically shown in fig. 1, such a mirror device may also have a drive unit for exciting rotation of the mirror device 10 about a first axis 12 and a second axis 14 having corresponding resonant frequencies. By appropriate design, the laser light impinging on the mirror 11 scans the desired area. In order to provide a physically satisfactory image for display applications, for example, the ratio between the resonant frequencies of the fast and slow axes must be within a small range around the target value. However, deviations from such target values are possible, for example, due to process variations. Disclosure of Invention According to an embodiment, a method for fabricating a microelectromechanical system mirror device is provided. The mirror portion of the mirror device is rotatable about a first axis having an associated first resonant frequency and a second axis different from the first axis and having an associated second resonant frequency. The method comprises estimating a deviation of a first geometry parameter of the mirror device from a reference value, and adjusting a manufacturing step of the mirror device to modify a second geometry parameter of the mirror device, the second geometry parameter being different from the first geometry parameter, such that a variation in a frequency ratio between the first resonant frequency and the second resonant frequency caused by the deviation of the first geometry parameter and the modification of the second geometry parameter is below a predefined threshold. According to another embodiment, a corresponding manufacturing apparatus is provided, which is configured to perform a plurality of manufacturing steps to manufacture a mirror device. The apparatus is configured to estimate a deviation of a first geometry parameter of the mirror device from a reference value and to adjust a manufacturing step of the plurality of manufacturing steps to modify a second geometry parameter as above. In another embodiment, a set of mems mirror devices of the same type is provided, wherein the mirror portion of each mirror device in the set is rotatable about a respective first axis having an associated first resonant frequency and a respective second axis different from the first axis and having an associated second resonant frequency. The set includes a first mirror device and a second mirror device. The first geometry parameter of the first mirror device differs from the first geometry parameter of the second mirror device by a first difference. Furthermore, the second geometry parameter of the first mirror device differs from the second geometry parameter of the second mirror device by a second difference. The difference between the first ratio between the first resonant frequency and the second resonant frequency of the first mirror device and the second ratio between the first resonant frequency and the second resonant frequency of the second mirror device, caused by the first difference only, is higher than 1%, and