WO2017202519A1

WO2017202519A1 - Moems device and corresponding manufacturing method

Info

Publication number: WO2017202519A1
Application number: PCT/EP2017/056787
Authority: WO
Inventors: Robert Kakonyi; Balazs Jatekos
Original assignee: Robert Bosch Gmbh
Priority date: 2016-05-24
Filing date: 2017-03-22
Publication date: 2017-11-30
Also published as: DE102016208926A1

Abstract

The invention provides a MOEMS device and a corresponding manufacturing method. The MOEMS device comprises a substrate (5), in which a well (C) is formed; a carrier portion (3), which is elastically suspended in the well (C) and is deflectable elastically at least along a first axis (x); a drive mechanism (D) provided in the well (C) for deflecting the carrier portion (3); a laser device (V), which is provided on or in the carrier portion (3) and is designed to emit a first laser beam (B) along a second axis (y), which extends substantially perpendicularly to the first axis (x); a lens device (15), which is mounted on the substrate (5) above the laser device (1') in such a way that it caps the well (C) and is configured in such a way that it transforms the first laser beam (B) into a second laser beam (B0) which forms an angle (a) with the second axis (y), which angle is a function of a deflection of the carrier portion (3) along the first axis (x); and a connecting device (A) for connecting an external control device (CU).

Description

Description title

MOEMS device and corresponding manufacturing method

The present invention relates to a MOEMS device and a corresponding manufacturing method.

State of the art

Although any optical devices and systems are applicable, the present invention and its underlying problem will be explained with reference to optical devices for distance measurement.

MOEMS devices are micro-opto-electro-mechanical devices which incorporate optical components, e.g. Laser sources, and micromechanical components, e.g. Have microgame gel.

More recently, optical systems for range finding have been developed using the line scan technique. The measurement principle is based on the determination of the length of the light path from a laser source to an object with an optical reflection surface. Known optical distance measuring systems comprise a micromirror which can be tilted about an axis, which deflects the laser beam and makes it possible to scan the distance of an object to be detected along a line. Recently, also with optical systems for distance measurement

worked two-dimensional scanning. The most difficult is the development of a suitable micromirror with the appropriate suspension and drive mechanism and its packaging. Due to such requirements, the sizes of conventional micromirror ranging optical systems range from several to several tens of mm. This limits their applicability in portable devices. US 2013/0063718 A1 describes a device for the optical measurement of a physical parameter with a laser light source for generating a measurement beam in the direction of an object and for receiving the object reflected by the object

Measuring beam, the measuring beam along an optical path, the variation of which depends on the physical parameter to be detected. The

Laser light source has an optical cavity. Furthermore provided are a

Motion sensor for the laser light source and elements for calculating the physical parameter from a signal measured at the laser light source and a signal measured by the motion sensor.

G. Giuliani et al., "Laser diode self-mixing technique for sensing applications", J. Opt. A: Pure Appl. Opt. 4 (2002), pages 283 to 294 describe the basics of

Laser diode self-mixing technique and its possible applications. Disclosure of the invention

The invention provides a MOEMS device according to claim 1 and a

corresponding manufacturing method according to claim 10. Preferred developments are the subject of the respective subclaims.

Advantages of the invention

The idea underlying the present invention is based on the fact that a single quasi-ideal lens in axis-parallel arrangement converts the axis movement of the laser source with a certain divergence into an angular deflection of a collimated laser beam.

The present invention provides a MOEMS device with a laser source, wherein the laser source is elastically deflectable at least along one axis, wherein above the laser source, a lens device is arranged, which converts the laser beam emitted from the laser source into a substantially parallel laser beam, wherein a Deflection angle of the converted laser beam depends on a deflection of the laser source along the axis. Since the angular deflection of the laser beam through the

Movement of the laser source along the axis is achieved by the lens device can be dispensed with a micromirror with elaborate suspension and packaging become. In particular, the space requirement is reduced because the tilting movement of the known micromirror is eliminated, so that the entire device can be made much smaller. According to a preferred embodiment, the carrier region is suspended by a spring device on opposite side walls of the substrate. This allows an elastic and stable suspension to be realized.

According to a further preferred development, the drive device comprises a capacitive drive. Such drives are easy to produce and energy-saving by means of micromechanical standard processes.

According to a further preferred development, the laser device has a

Receiver device, such as a photodiode, for receiving a second laser beam reflected from an external object. Thus, a simple arrangement for the self-mixing process can be produced integrated, in which the receiver is close to the transmitter.

According to a further preferred development, a beam splitter device for splitting the second laser beam into two components is attached to the lens device. Thus, a simple arrangement for the self-mixing process can be produced integrally, in which the receiver is provided externally.

According to a further preferred development, the lens device is designed such that it transforms the first laser beam into a substantially collimated second laser beam. This increases the resolution during scanning. In certain applications, it is also possible that the laser beam is not collimated, but collimation is performed only at a certain distance from the MOEMS device.

According to a further preferred refinement, the carrier region elastically suspended in the cavity is elastically deflectable along a third axis, which runs essentially perpendicular to the second axis, wherein the lens device is designed such that it transforms the first laser beam into a second laser beam, which comprises a first laser beam Wnkel forms with the second axis, which is dependent on a deflection of the support area along the first axis and the third axis, so that a Area is scanned by the second laser beam. This allows the scan area to be enlarged without significantly increasing the space requirement.

According to a further preferred development, the laser device has a laser diode. Such laser diodes can be produced with very small dimensions.

According to a further preferred development, the laser device is in the

Integrated carrier area. Thus, eliminating the need for mounting another component, and the space required is further reduced.

Brief description of the drawings

Further features and advantages of the present invention will be explained below with reference to embodiments with reference to the figures.

Show it:

Fig. 1 is a schematic representation for explaining the present

Invention underlying principle of operation;

Fig. 2a), b) are schematic cross-sectional views of a MOEMS device according to a first embodiment of the present invention;

Fig. 3 is a schematic cross-sectional view of a MOEMS device

according to a second embodiment of the present invention; and

Fig. 4 is a schematic cross-sectional view of a MOEMS device

according to a third embodiment of the present invention. Embodiments of the invention

In the figures, like reference numerals designate the same or functionally identical

Elements. Fig. 1 shows a schematic representation for explaining the present

Invention underlying principle of operation. In Fig. 1, reference numeral 1 denotes a laser source which is arranged in an x / y coordinate system. A quasi-ideal lens 10 is arranged axis-parallel to the y-axis and symmetrical to the x-axis. The laser source 1 is offset by the focal length f of the lens 10 in the negative x direction and by a distance

Äy = h offset in y direction. By means of the lens device 10, a laser beam B generated by the laser source 1 is converted into a parallel laser beam B ', which forms an angle α with the x-axis. The angle α is proportional to the deflection A y in the positive or negative y direction. If Äy = 0, then the angle α = 0 °. According to this operating principle, a variable angular deflection of the laser beam B 'can be achieved by generating a variable deflection A y of the laser source 1 in the y direction.

Fig. 2a), b) are schematic cross-sectional views of a MOEMS device according to a first embodiment of the present invention.

In Fig. 2a), b) reference numeral 5 denotes a substrate, for example a

Wafer substrate, which has a cavity C, which is enclosed by the side walls 5a, 5b and the bottom wall 5c of the substrate 5. At the top of the side walls 5a, 5b, a lens device 15 is attached, for example, by a bond K, whereby the cavity C is closed.

In the cavity C, a laser source T is mounted on a carrier region 3, which is elastically deflectable one-dimensionally along the x-axis by a drive D (shown only schematically). The support portion 3 is connected via spring means 2a, 2b with suspension portions 4a, 4b on the side walls 5a and 5b. The

Radiation direction of the laser source 1 'runs along the y-axis.

The (only schematically illustrated) drive D is, for example, by means of comb electrode means formed outside the plane of the drawing or

Realized plate electrode devices.

The laser beam B0 emitted by the laser source 1 'in the y-direction is transmitted through the

Lens device 15 is converted into a substantially parallel laser beam B0, which emerges from the lens device 15. According to FIG. 2a), the carrier region 3 with the laser source T is in the undeflected state x = 0, so that the deflection angle α from the y-axis is α = 0 °.

According to FIG. 2b), the deflection of the carrier region 3 is x = x1 in the negative x-direction, so that the deflection angle α of the laser beam BO is α = α1. By means of a periodic or aperiodic deflection in the positive and negative x-direction, a predetermined angular range can thus be scanned by the laser beam BO.

In order to control the drive D and the laser source 1 '(shown only schematically), the MOEMS device 100 is connected via a connection device A by means of an external line device L to an external control unit CU. Within the substrate 5, the connection device A extends over integrated strip conductors, which are not shown for reasons of simplicity. To carrier area 3 and the

Laser source T are these integrated interconnects, for example via the

Spring devices 2a, 2b out.

The production of the MOEMS device 100 takes place by means of customary micromechanical standard processes, the carrier region 3, the drive D and the spring devices 2a, 2b being etched, for example, by a sacrificial layer process from a micromechanical functional layer of polysilicon.

The laser source 1 'can either be integrated into the carrier region 3 by means of a corresponding layer structure or be attached to this as a separate component. Likewise, the lens device 15 can either be formed by a closing process with a subsequent structuring process or glued as a separate component onto the side walls 5a, 5b of the substrate 5 by means of the adhesive K shown.

The (only schematically illustrated) drive D can be either resonant with low power consumption or quasi-static depending on the application. If a two-axis drive is used, for example with additional suspension and additional electrodes in the z-direction, eg a Lissajous pattern can be drawn on an object to be scanned. The Lissajous pattern better obscures the accessible rectangular scan interval if the frequencies of the two oscillations are close together. Accordingly, the drive mechanisms in the two Directions are very similar or identical. For a quasi-static drive D, a regular pattern, eg zigzag pattern, is preferred.

3 is a schematic cross-sectional view of a MOEMS device according to a second embodiment of the present invention.

The MOEMS device 200 shown in Fig. 3 differs from the embodiment shown in Fig. 2a), b) in that it constitutes a distance measuring system. Accordingly, the MOEMS system 200 receives the laser beam B0 'reflected from an object G with a receiving device, such as a

Photodiode. 3, this photodiode is integrated into the laser source 1 ". A corresponding evaluation of the received light signals B0 'from an object G in relation to the emitted light signals B takes place in the control unit CU', for example by means of the self-mixing method.

4 is a schematic cross-sectional view of a MOEMS device according to a second embodiment of the present invention.

The MOEMS device 300 according to the third embodiment is based on the first embodiment shown in FIG. 2 a), b), but additionally has a beam splitting device 50 mounted on the lens device 15. The beam splitting device 50 operates according to the Michelson principle and allows the laser beam B0 emerging from the lens device 15 to pass partially onto the object G to be detected and partly onto a receiver device PD in the form of a photodiode which is connected to the

The laser beam B0 'reflected by the object G is likewise directed to the receiver device PD by the beam deflection device 50, so that an evaluation by means of the self-mixing technique can likewise be carried out It is likewise conceivable to produce the beam deflection device 50 directly on the lens device 15 by means of a micromechanical process. Although the present invention has been described in terms of preferred embodiments, it is not limited thereto. In particular, the materials and topologies mentioned are only examples and not limited to the illustrated examples.

Although in the above-described embodiments reference has been made in particular to an optical device for distance determination, the invention is not limited thereto but can be used for any applications in which a scanned laser beam is generated and, if necessary, a reflected laser beam has to be detected.

The substrate may be both a laser substrate, as described above, and a chip substrate, wherein, for example, a plurality of chips are produced on a laser with a corresponding MOEMS device.

Claims

Claims 1. A MOEMS apparatus comprising: a substrate (5) in which a cavity (C) is formed; a carrier region (3) which is elastically suspended in the cavity (C) and which is elastically deflectable at least along a first axis (x); a drive device (D) provided in the cavity (C) for deflecting the carrier region (3); a laser device (1 '; 1 ") provided on or in the carrier region (3) and configured to emit a first laser beam (B) along a second axis (y) which is substantially perpendicular to the first axis (x) a lens device (15) mounted above the laser device (V; 1 ") on the substrate (5) so as to cap the cavity (C) and configured to receive the first laser beam (B) in transformed a second laser beam (B0) which forms an angle (a) with the second axis (y), which depends on a

Deflection of the carrier region (3) along the first axis (x); and connection means (A) for connecting an external control device (CU; CIT; CU ").

2. MOEMS device according to claim 1, wherein the carrier region (3) via a

Spring means (2a, 2b) on opposite side walls (5a, 5b) of the substrate (5) is suspended.

3. MOEMS device according to claim 1 or 2, wherein the drive device (D) comprises a capacitive drive.

4. MOEMS device according to one of the preceding claims, wherein the

Laser device (1 ") a receiver device, such as a photodiode, for Receiving a second laser beam (ΒΟ ') reflected by an external object (G).

5. MOEMS device according to one of claims 1 to 3, wherein at the

Lens means (15) a beam splitter device (50) for dividing the second

Laser beam (ΒΟ ') is mounted in two components.

6. MOEMS device according to one of the preceding claims, wherein the

Lens device (15) is designed such that it transforms the first laser beam (B) into a substantially collimated second laser beam (B0).

7. MOEMS device according to one of the preceding claims, wherein in the cavity (C) elastically suspended support portion (3) along a third axis (z) is elastically deflectable, which is substantially perpendicular to the second axis (y), and wherein the lens device (15) is designed such that it transforms the first laser beam (B) into a second laser beam (B0) which forms an angle (a) with the second axis (y) which depends on a deflection of the carrier region (3 ) along the first axis (x) and the third axis (z), so that a surface area can be scanned by the second laser beam (ΒΟ ').

8. MOEMS device according to one of the preceding claims, wherein the

Laser device (1 ', 1 ") has a laser diode.

9. MOEMS device according to one of the preceding claims, wherein the

Laser device (1 ', 1 ") is integrated in the carrier region (3).

10. A method of manufacturing a MOEMS apparatus comprising the steps of: providing a substrate (5) in which a cavity (C) is formed;

Provision of a in the cavity (C) elastically suspended support portion (3) which is at least along a first axis (x) elastically deflectable;

Providing a drive device (D) provided in the cavity (C) for deflecting the carrier area (3); Providing a laser device (1 '; 1 ") on or in the carrier region (3) which is designed to emit a first laser beam (B) along a second axis (y) which is substantially perpendicular to the first axis (x) Mounting a lens device (15) above the laser device (1 '; 1 ") on the substrate (5) so as to cap the cavity (C) and configured to transform the first laser beam (B) into a second one Laser beam (BO) which forms an angle (a) with the second axis (y) which is dependent on a deflection of the carrier region (3) along the first axis (x); and

Forming a connection device (A) for connecting an external

Control device (CU; CIT; CU ").