JP2009154264A - Mems module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a MEMS module which is easy to align with a package when mounting a MEMS device, has high alignment accuracy and can downsize the package. <P>SOLUTION: A plurality of lead pins 20 are provided on a pedestal 19 of the package 3. A lead pin insertion hole 17 is provided at a position of the MEMS device 2 corresponding to the lead pin 20. The lead pin 20 is inserted through the lead pin insertion hole 17 and the MEMS device 2 is mounted on the pedestal 19. Thereafter, the lead pin 20 and an electrode pad of the MEMS device 2 are electrically connected. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a MEMS module, and more particularly to a MEMS module in which a MEMS device is mounted in a package.

  A MEMS (Micro Electro Mechanical System) device is a device that realizes an electromechanical system with a fine structure and has a wide range of application fields. Among them, in the optical field, for example, it is widely used for optical switches, optical attenuators, optical scanners, etc. ing.

  In this case, a micromirror is formed in a part of the MEMS device, and the light irradiated from the light source toward the micromirror is reflected by the micromirror by electrically controlling the mechanical movement of the micromirror. The reflected light reflected from the surface switches the optical axis, tilts the optical axis, or scans the optical axis at high speed, and thus plays a role in the main components in each of the optical switch, optical attenuator, and optical scanner. It is what you bear.

  In order to apply a MEMS device in the optical field, it is necessary to have a high alignment accuracy of the optical axis of light reflected by a micromirror with respect to an optical system that employs the MEMS device. Increasing mounting accuracy is a very important requirement.

  Incidentally, as a conventional mounting form of the MEMS device, a MEMS module 50 as shown in FIG. 7 has been proposed. A lead pin 54 extending from the inside of the package main body 53 to the outside of the package main body 53 is provided at the joint portion of the package main body 53 in which the concave lower package portion 51 and the upper package portion 52 having an opening are connected and integrated. It has been.

  Then, the MEMS device 55 is mounted (die bonding) on the inner bottom surface 56 of the lower package portion 51, and an electrode pad (not shown) formed on the MEMS device 55 and the lead pin 54 are connected by a bonding wire 57 ( The electrical connection between the MEMS device 55 and the lead pin 54 is achieved by wire bonding (see, for example, Patent Document 1).

Further, as another mounting form, a MEMS module 60 as shown in FIG. 8 is conceivable. That is, a MEMS device 63 is die-bonded (hereinafter abbreviated as D / B) on an insulating pedestal portion 62 through which a plurality of lead pins 61 are inserted, and electrode pads 64 and lead pins formed on the MEMS device 63. The MEMS device 63 and the lead pin 61 are electrically connected by wire bonding 61 (hereinafter abbreviated as W / B) with a bonding wire 65.
JP 2007-281021 A

  By the way, in any of the above-described mounting forms, the alignment (alignment) of the MEMS device at the time of D / B is performed on the surface on which the MEMS device is D / B imaged by the imaging camera attached to the die bonder. This is performed based on the alignment mark and the image of the MEMS device.

  Therefore, in the MEMS module 50 having the configuration shown in FIG. 7, the mounting accuracy of the MEMS device 55 with respect to the package 53 is mainly determined by the mechanical accuracy of the die bonder which is a manufacturing apparatus. Accompanying the cost increase of the equipment.

  In addition, when a plurality of die bonders are operated, the difference in performance of individual manufacturing apparatuses causes a difference in mounting accuracy of MEMS devices, resulting in variations in mounting accuracy of MEMS devices among manufacturing apparatuses. That is, a product whose performance quality is not stable is manufactured.

  On the other hand, in the MEMS module 60 having the configuration of FIG. 8, the mounting accuracy of the MEMS device 63 depends on the mechanical accuracy of the die bonder as described above, and the outer shape of the mounting MEMS device 63 of the pedestal portion 62 on which the MEMS device 63 is mounted. It is necessary to provide the alignment mark 66 outside the corresponding position. For this reason, the dimension of the pedestal portion 62 becomes larger than one dimension of the outer dimension of the MEMS device 63. As a result, the dimension of the MEMS module 60 is increased, and the advantage of downsizing the MEMS device 63 is not utilized.

  In many cases, the MEMS device 63 has a structure including a movable portion in the MEMS device 63, and in the pickup of the MEMS device 63 at the time of D / B, a portion that becomes the movable portion of the MEMS device 63 is an upper portion. There is a concern that the suction chucking method may adversely affect various characteristics of the device.

  Therefore, this type of die bonder cannot be used, and instead, a die bonder of a type that picks up across the opposite ends of the MEMS device is used.

  However, when such a type of die bonder is used, the package is not allowed to be positioned within the movement range of the pickup head, and there is a problem that the package must be enlarged.

  A method of automatically aligning a MEMS device with respect to a package by forming an insertion hole for alignment in a part of the MEMS device in a processing process of the MEMS device and inserting the insertion hole into an alignment pin attached to the package (Pin alignment method) is also available.

  In this alignment method, since the distance between the electrode pad provided in the MEMS device and the lead pin provided in the housing is large, the bonding wire is imaginary for connecting the electrode pad and the lead pin to achieve electrical conduction between the MEMS device and the housing. The wiring distance becomes longer. Therefore, the bonding wire must be wired in a loop shape bulging upward so that the bonding wire does not contact the device and cause an electrical failure.

  As a result, downsizing of the package is hindered, and an increase in the L (inductance) and C (capacitance) components due to the bonding wire causes a delay in the high-frequency signal, and an increase in the R (resistance) component causes a power loss. .

  The bonding wire is made of a gold wire or an aluminum wire, and there is a concern about an increase in material cost due to the long wiring of the bonding wire.

  Therefore, the present invention was devised in view of the above problems, and an object of the present invention is to provide a MEMS module that can be easily aligned when a MEMS device is mounted on a package, has high alignment accuracy, and can be downsized. It is to provide.

In order to solve the above problems, the invention described in claim 1 of the present invention is:
A package including a pedestal part and a plurality of lead pins penetrating the pedestal part;
A MEMS device having a lead pin insertion hole at a position corresponding to the electrode pad and the lead pin,
The lead pin is inserted into the lead pin insertion hole, the MEMS device is placed on the pedestal portion, and the lead pin and the electrode pad are electrically connected.

  Moreover, the invention described in claim 2 of the present invention is that in claim 1, the surface of the pedestal portion on which the MEMS device is mounted and the surface of the MEMS device on the side of the pedestal portion have substantially the same shape and dimensions. It is characterized by being.

  In addition, the invention described in claim 3 of the present invention is characterized in that, in any one of claims 1 and 2, both the lead pins and the lead pin insertion holes are plural. .

  Moreover, the invention described in claim 4 of the present invention is that, in any one of claims 1 to 3, the lead pin protrudes from a surface of the pedestal portion on which the MEMS device is mounted. It is a feature.

  In the present invention, a plurality of lead pins are provided on a pedestal portion of a package, a lead pin insertion hole is provided at a position corresponding to the lead pin of the MEMS device, and the lead pin is inserted into the lead pin insertion hole to place the MEMS device on the pedestal portion. Thereafter, the lead pins and the electrode pads of the MEMS device were electrically connected.

  As a result, it was possible to realize a MEMS module that can be easily aligned when the MEMS device is mounted on the package, has high alignment accuracy, and can be downsized.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIG. 1 to FIG. 6 (the same parts are given the same reference numerals). The embodiments described below are preferable specific examples of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention particularly limits the present invention in the following description. Unless stated to the effect, the present invention is not limited to these embodiments.

  Example 1 is an optical deflector module using a MEMS device. The optical deflector module 1 includes a MEMS device 2 having an optical deflection function and a package 3 as shown in FIG. 1, and has a structure in which the MEMS device 2 is mounted on a base 19 of the package 3 as shown in FIG. Yes.

  In FIG. 1, reference numeral 4 is an SOI substrate, 12a to 12d are piezoelectric actuator sections, 13 is a mirror section, 15a to 15d are vibration sections, 16a and 16b are elastic support sections, and 17 is a lead pin insertion hole. In FIG. 2, reference numeral 19 denotes a pedestal portion, and 20 denotes a lead pin.

  A method for manufacturing a MEMS device will be described with reference to the process diagram of FIG. 3 is a cross-sectional view taken along line XX in FIG.

In the step of FIG. 3A, the substrate is a three-layer SOI substrate 4, and a support layer made of single crystal silicon having a layer thickness of 525 μm is disposed on both sides of an intermediate oxide film layer (Box layer) 5 having a layer thickness of 2 μm. A (Handle layer) 6 and an active layer (SOI layer) 7 made of single crystal silicon having a layer thickness of 30 μm are located. Then, SiO ₂ films (thermally oxidized silicon films) 8 a and 8 b having a film thickness of 500 nm are formed on the active layer 7 and the support layer 6 of the SOI substrate 4 using a diffusion furnace.

In the step (b), by sputtering on the SiO ₂ film 8a forming a Pt film of Ti film and the thickness 150nm of sequentially thickness 50nm from the SiO ₂ film 8a side, the lower electrode 9 of a two-layer structure Form.

  Next, a film is formed on the Pt film of the lower electrode 9 by a reactive arc discharge ion plating method (see Japanese Patent Laid-Open Nos. 2001-234331, 2002-177765, and 2003-81694). A piezoelectric film 10 is formed by forming a lead zirconate titanate film (hereinafter referred to as PZT) that is a piezoelectric material having a thickness of 3 μm.

  Further, a Pt film having a film thickness of 150 nm is formed on the piezoelectric film 10 by sputtering to form the upper electrode 11.

  In the step (c), the Pt upper electrode 11 is patterned by the photolithographic technique and the dry etching technique to form four independent upper electrodes 11a, 11b, 11c, and 11d, respectively. Similarly, the PZT piezoelectric film 10 and the Pt / Ti lower electrode 9 is patterned to form piezoelectric films 10a, 10b, 10c, and 10d and lower electrodes 9a, 9b, 9c, and 9d, which are located below upper electrodes 11a, 11b, 11c, and 11d, respectively. Layered piezoelectric actuator portions 12a, 12b, 12c, and 12d are fabricated.

  At this time, the central portion of the Pt / Ti lower electrode 9 is protected from dry etching by the resist, and the remaining lower electrode 9e functions as a reflective film constituting the mirror portion 13 of the MEMS device.

  In order to increase the light reflection efficiency of the mirror part 13, after a metal reflective material such as Al or Au is formed by sputtering, Al or Au or the like is formed on the lower electrode 9e of the mirror part 13 by a photolithography technique and a dry etching technique. A metal reflective film is formed by

In the step (d), the surface on which the piezoelectric actuator portions 12a, 12b, 12c and 12d and the mirror portion 13 are formed is protected with a thick film resist over the entire surface, and the SiO ₂ film 8b on the support layer 6 side is protected. After removing with buffered hydrofluoric acid (BHF), an Al film 14 is formed on the support layer 6 by sputtering. Thereafter, the Al film 14 is patterned by a photolithography technique and a dry etching technique to form an ICP-RIE hard mask using the Al film 14.

In the step (e), the thick film resist provided on the surface on which the piezoelectric actuator portions 12a, 12b, 12c, 12d and the mirror portion 13 are formed is peeled off, and a resist pattern by the photolithography technique is again formed on the same surface side. An unnecessary part of the SiO ₂ film 8a on the SOI substrate 4 and the active layer 7 of the SOI substrate 4 is removed using an ICP-RIE apparatus as a mask.

  Then, on the intermediate oxide film layer 5 of the SOI substrate 4, separate mirror units 13, vibrating units 15 a, 15 b, 15 c, 15 d located below the piezoelectric actuator units 12 a, 12 b, 12 c, 12 d, and Elastic support portions 16a and 16b are formed.

  However, the removed portion also includes a lead pin insertion hole 17a that performs an alignment function by inserting a lead pin 20 to be described later when mounted on the package base.

  In the step (f), unnecessary portions of the support layer 6 are removed by dry etching using an ICP-RIE apparatus to form the oscillating space 18 of the mirror portion 13 and the lead pin insertion hole 17b.

  In the step (g), an unnecessary portion of the intermediate oxide film layer 5 is removed with a BHF solution to form a swinging space 18 of the mirror portion 13 and a lead pin insertion hole 17.

  Thereafter, the above-described SOI wafer is cut and divided in a subsequent dicing process, whereby a plurality of individual MEMS devices 2 having an optical deflection function are completed.

  As shown in FIG. 1, the package 3 for mounting the MEMS device 2 manufactured through the above manufacturing process includes a pedestal 19 having the same outer dimensions as the MEMS device 2 to be mounted, and the pedestal 19 of the MEMS device 2. The lead pin 20 is provided at a position corresponding to the lead pin insertion hole 17.

  The lead pins 20 are linear straight pins that pass through the pedestal portion 19, and are arranged in parallel with each other. The end surface 20 a of the pedestal portion 19 on the side where the MEMS device 2 is mounted of the lead pin 20 is the MEMS of the pedestal portion 19. At a position protruding 600 μm from the device mounting surface 19a.

  Then, as shown in FIG. 2, the lead pin insertion hole 17 of the MEMS device 2 is fitted into the lead pin 20 of the package 3, thereby aligning the position of the MEMS device 2 with respect to the package 3, and an adhesive such as epoxy resin (not shown). The MEMS device 2 is bonded and fixed on the pedestal 19 of the package 3 via

  Finally, the end face 20a of each lead pin 20 and the electrode pad of the MEMS device 2 (the upper electrodes 11a, 11b, 11c, and 11d of the piezoelectric actuator portions 12a, 12b, 12c, and 12d) are connected by the bonding wire 21, and the optical deflector module 1 is completed. A sealing cap with an optical window is disposed integrally with the pedestal 19 above the MEMS device 2 as necessary.

  Next, an operation test performed on the optical deflector module and a test result thereof will be described. Two piezoelectric actuator units 12a, 12b out of four piezoelectric actuator units 12a, 12b, 12c, 12d provided separately and independently from an external power source via lead pins 20 and bonding wires 21 of the optical deflector module 1. A sine wave bias voltage was applied to the. The applied voltage had a frequency of 5 kHz and an amplitude (Vpp) of 20V.

  At the same time, a bias voltage of a sine wave having the same frequency and amplitude as the applied voltage but different in phase (reverse phase) is applied to the other two piezoelectric actuator units 12c and 12d, and the rotational vibration of the mirror unit 13 at that time is applied. I tried to verify.

  As a verification method, the reflecting surface of the mirror unit 13 is irradiated with laser light from a He—Ne laser, and the reflected light reflected by the reflecting surface of the mirror unit 13 is projected onto a screen arranged at a predetermined distance. Thus, the rotation angle of the mirror unit 13 was calculated. As a result, the rotation angle was found to be ± 10 °.

  That is, in the optical deflector module 1 of this embodiment, the drive frequency of the voltage actuator units 12a, 12b, 12c, and 12d of the MEMS device 2 is set to the mechanical resonance frequency (5 kHz) of the mirror unit 13 including the elastic support units 16a and 16b. It was proved that the rotational angle of the rotational vibration of the mirror portion 13 can be increased even when driven at a low voltage.

  At the same time, by inserting the lead pins of the package into the lead pin insertion holes of the MEMS device at the time of mounting the MEMS device on the package, alignment of the mounting position with respect to the package of the MEMS device is performed automatically and with high accuracy.

  Therefore, in the laser scanning optical system provided with the optical deflector module of the present invention, by matching the shape dimension of the optical deflector module holding portion of the holder that supports the optical deflector module with the external dimension of the optical deflector module. When the optical deflector module is supported by the holder, the optical alignment of the optical deflector module in the laser scanning optical system is automatically performed with high accuracy. That is, the optical alignment of the optical deflector module in the laser scanning optical system can be easily and accurately performed.

  FIG. 4 is a schematic diagram illustrating a package according to the second embodiment. In Example 2, the structure and manufacturing process of the MEMS device to be used are the same as those used in Example 1, and the mounting method of the MEMS device on the package is performed in the same manner as in Example 1. Only the shape is different. Therefore, only the description of the package will be given below, and the description of the MEMS device and the mounting method for the package of the MEMS device will be omitted.

  As shown in FIG. 4, the lead pin 20 provided on the package 3 protrudes from the surface of the pedestal portion 19 where the MEMS device is mounted, and is bent substantially parallel to the opposite surface of the pedestal portion 19 and at a substantially right angle toward the outside. ing. The optical deflector module of Example 2 using this package is suitable for surface mounting on a circuit board.

  FIG. 5 is a schematic diagram illustrating a package according to the third embodiment. In Example 3, the structure and manufacturing process of the MEMS device to be used are the same as those used in Examples 1 and 2, and the method for mounting the MEMS device on the package is the same as in Examples 1 and 2. Only the shape of the package is different. Therefore, only the description of the package will be given below, and the description of the MEMS device and the mounting method for the package of the MEMS device will be omitted.

  From FIG. 5, the lead pin 20 provided in the package 3 protrudes from the surface of the pedestal portion 19 where the MEMS device is mounted, and the flat lead pin 20 is formed on the opposite surface and side surface from the opposite surface side of the pedestal portion 19. It is bent along. The optical deflector module of Example 2 using this package is suitable for surface mounting on a circuit board by printing solder reflow.

  FIG. 6 is a schematic diagram illustrating a package according to the fourth embodiment. In Example 4, the structure and manufacturing process of the MEMS device to be used are the same as those used in Examples 1, 2, and 3, and the mounting method for the MEMS device package is also described in Examples 1, 2, and 3. And 3 and only the shape of the package is different. Therefore, only the package will be described below, and the description of the MEMS device and the mounting method of the MEMS device on the package will be omitted.

  As shown in FIG. 6, the lead pin 20 is a straight straight pin that penetrates the pedestal 19, but the lead pins 20 are arranged such that the apex angles of the quadrangles with the lead pins 20 as vertices are not equal to each other. It has an asymmetrical arrangement. Accordingly, the lead pin insertion hole of the MEMS device is also provided at a position corresponding to the lead pin 20.

  Therefore, the mounting direction of the MEMS device with respect to the package is uniquely determined, and an electrical failure caused by mounting in the wrong direction can be prevented. In particular, the package configuration is indispensable when the structure of the surface direction of the MEMS device is asymmetric.

  As described above in detail, the MEMS module of the present invention uses the lead pins provided in the package for positioning at the time of mounting the MEMS device. Therefore, the MEMS module can be positioned with high accuracy without enlarging the package. Can be combined.

  In addition, the lead pin insertion hole used for alignment at the time of mounting on the package of the MEMS device is formed in the frame portion that supports the movable portion of the MEMS device within the process of the manufacturing process of the MEMS device. Therefore, a separate process only for forming the lead pin insertion hole in the MEMS device is not required.

  In addition, since the lead pins provided in the package are used for positioning at the time of mounting the MEMS device, it is not necessary to mount image recognition means including an imaging camera as in the conventional case in the manufacturing facility.

  Further, since the package can be made the same size as the MEMS device, the MEMS module on which the MEMS device is mounted can be downsized, and the electrode pad and the housing provided on the MEMS device are provided. The distance between the lead pins is shortened, and the distance between the overhead wires of the bonding wires that connect the electrode pads and the lead pins to establish electrical continuity between the MEMS device and the housing is shortened, realizing excellent high frequency characteristics and reducing power loss. . Shortening the bonding wire also contributes to a reduction in material costs.

  In addition, by setting the protrusion length of the lead pin from the mounting surface of the MEMS device to the thickness of the MEMS device + α, the wiring swelled in a loop shape of the bonding wire can be eliminated, and excellent high frequency characteristics And a MEMS module with low power loss.

  Furthermore, by providing an electrode pad near the lead pin insertion hole of the MEMS device, it is possible to connect the electrode pad and the lead pin via solder or conductive paste, and wireless power feeding that does not require a bonding wire is also possible It is.

It is a three-dimensional exploded view showing Example 1 of the present invention. Similarly, the schematic which shows Example 1 of this invention. It is a manufacturing-process figure of the MEMS device which concerns on this invention. It is the schematic of the package which concerns on Example 2 of this invention. It is the schematic of the package which concerns on Example 3 of this invention. It is the schematic of the package which concerns on Example 4 of this invention. It is a schematic explanatory drawing of a prior art example. Similarly, it is a schematic explanatory drawing of a prior art example.

Explanation of symbols

1 optical deflector module 2 MEMS device 3 package 4 SOI substrate 5 intermediate oxide film layer 6 supporting layer 7 active layer 8a, 8b SiO ₂ film 9 lower electrode 9a, 9b, 9c, 9d, 9e lower electrode 10 piezoelectric film 10a, 10b 10c, 10d Piezoelectric film 11 Upper electrode 11a, 11b, 11c, 11d Upper electrode 12a, 12b, 12c, 12d Piezoelectric actuator part 13 Mirror part 14 Al film 15a, 15b, 15c, 15d Vibration part 16a, 16b Elastic support part 17 Lead pin insertion hole 17a, 17b Lead pin insertion hole 18 Oscillating space 19 Base 19a MEMS device mounting surface 20 Lead pin 20a End surface 21 Bonding wire

Claims (4)

A package including a pedestal part and a plurality of lead pins penetrating the pedestal part;
A MEMS device having a lead pin insertion hole at a position corresponding to the electrode pad and the lead pin,
The MEMS module, wherein the lead pin is inserted into the lead pin insertion hole, the MEMS device is placed on the pedestal portion, and the lead pin and the electrode pad are electrically connected.   The MEMS module according to claim 1, wherein a surface of the pedestal portion on which the MEMS device is mounted and a surface of the MEMS device on the pedestal portion side have substantially the same shape and dimensions.   The MEMS module according to claim 1, wherein the number of the lead pins and the lead pin insertion holes is plural.   The MEMS module according to any one of claims 1 to 3, wherein the lead pin protrudes from a surface of the pedestal portion on which the MEMS device is mounted.

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