JP6675181B2 - Transducer device and manufacturing method thereof - Google Patents

Description

  The present invention relates to a transducer device and a method of manufacturing the same, and more particularly to a configuration of a MEMS (Micro Electro Mechanical System) device for performing conversion between physical quantity and electricity, and a structure of a transducer device packaged on a chip scale and a method of manufacturing the same.

  FIG. 8 shows a configuration of a microphone device as an example of a conventional transducer device. In FIG. 8, reference numeral 1 denotes a fixed electrode, 2 denotes a movable electrode (membrane), and 3 denotes a fixed electrode 1 and a movable electrode 2. A conversion unit (transducer) 4 is a signal processing circuit for performing signal processing such as amplification of a signal from the conversion unit 3, 6 is a printed circuit board (PCB) on which external capacitors 7 and external terminals 8 are formed, and 9 is bonding A wire 10 is a protective resin, 11 is a metal lid (shield member) on which an acoustic port 12 is formed, and 13 is a back chamber.

  In such a microphone device, when the movable electrode 2 vibrates due to the sound pressure from the acoustic port 12, the change in capacitance at this time is captured by the converter 3, and the signal from the converter 3 is amplified by the signal processing circuit 4. Thus, sound can be output as an electric signal.

JP 2014-523815 A

  By the way, in the microphone device shown in FIG. 8, a chip of the conversion unit 3 or the signal processing circuit 4 as the MEMS is mounted on the existing printed circuit board 6 with the bonding wire 9 and the acoustic port 12 is formed. A structure in which the lid 11 is covered is adopted, and such a structure has a physical limit to cope with recent miniaturization.

Further, in the manufacture of the converter 3, a predetermined space is formed between the fixed electrode 1 and the movable electrode 2 by forming a sacrificial layer between the fixed electrode 1 and the movable electrode 2. , The production becomes complicated.
Further, the use of the printed circuit board 6 has a disadvantage that the temperature use range of the device is narrowed.

  The printed circuit board 6 incorporates various elements such as a capacitor 7 as external components as viewed from the conversion unit 3 and the signal processing circuit 4. There is a problem that is rising.

  The present invention has been made in view of the above problems, and its object is to make it possible to reduce the size by miniaturization, facilitation of manufacturing, monolithic processing, etc., and to widen the temperature use range. An object of the present invention is to provide a transducer device and a method of manufacturing the same.

In order to achieve the above object, a transducer device according to the first aspect of the present invention forms a movable electrode of a converter, an insulating film ring, a wiring layer, and a signal processing circuit connected to the converter via the wiring layer. The first substrate, the fixed electrode of the conversion unit, the protrusion abutting on the insulating film ring, and the cavity disposed inside the fixed electrode in communication with the fixed electrode are formed, and an acoustic port is provided around the cavity. A second substrate provided with an air passage communicating with the conversion section , a predetermined space is secured between the fixed electrode and the movable electrode, and the two electrodes are arranged in parallel with the insulating film ring; The first substrate and the second substrate are joined so that the projections come into contact with each other and the air passage communicates with the movable electrode on the first substrate side .

According to a second aspect of the present invention, there is provided a method of manufacturing a transducer device, comprising: a plurality of first substrates each including a movable electrode of a converter, an insulating film ring, a wiring layer, and a signal processing circuit connected to the converter via the wiring layer. Is formed on a first wafer, and the fixed electrode of the conversion section, the protrusion contacting the insulating film ring, a cavity communicated with the fixed electrode and arranged inside, and an acoustic port arranged around the cavity are provided. A plurality of second substrates having an air passage communicating with the conversion unit from the second wafer, the movable electrode of each of the plurality of first substrates and the fixed electrode of each of the plurality of second substrates, The insulating film ring of each of the plurality of first substrates and the protruding portions of each of the plurality of second substrates are in contact with each other while securing a predetermined space between the electrodes and arranging the two electrodes in parallel. The first wafer and the second wafer are overlapped and joined so that each of the air passages of the plurality of second substrates communicates with the movable substrate of each of the plurality of first substrates on the side of the first substrate. The method is characterized in that the first and second wafers are made into individual pieces and manufactured .
According to a third aspect of the present invention, the signal processing circuit is provided at a position in the longitudinal direction of the first substrate of the first wafer that is aligned with the conversion section, and the signal processing circuit and the conversion section are connected by a wiring layer. It is characterized by the following.

  According to the above configuration, the movable electrode of the conversion unit, the signal processing circuit, the wiring layer connecting the signal processing circuit to the conversion unit, other elements, and the like are formed on the first wafer (or the first substrate) made of, for example, silicon. A fixed electrode of the conversion part, a cavity (or a back chamber) arranged at the center of the device on the front side of the fixed electrode, etc., on a second wafer (or second substrate) made of silicon on which external electrodes and the like are formed. Acoustic ports (holes) and the like are arranged outside the box. Then, the fixed electrode and the movable electrode constituting the conversion section are arranged so as to overlap while securing a predetermined space therebetween, and the first wafer (or the first substrate) and the second wafer (or the second substrate) are arranged. Are joined and finally singulated to produce a large number of transducer devices.

According to the present invention, for example, by stacking two wafers or substrates using silicon, bonding them on a chip scale, and packaging them, a transducer device can be manufactured. By using the first and second substrates as silicon substrates, the temperature use range is widened, and the use at high temperatures is possible.
In addition, by arranging the conversion unit and the signal processing circuit in the vertical direction, it is possible to further reduce the size of the device, including connecting the conversion unit and the signal processing circuit with a wiring layer via an insulating layer. By manufacturing the transducer device (MEMS device) by a monolithic manufacturing method (semiconductor microprocess), it is possible to further facilitate the manufacturing and reduce the cost, and there is an advantage that the degree of freedom in design is increased. That is, in a device using a conventional printed circuit board (PCB), each element is incorporated as an external component from the viewpoint of a conversion unit and a signal processing circuit. However, according to the present invention, monolithic processing using a silicon substrate (semiconductor substrate) can be performed, so that the degree of freedom of design increases and the cost can be further reduced.

Furthermore, since the space between the fixed electrode and the movable electrode can be secured by stacking two wafers or substrates, there is no need to form a sacrifice layer as in the conventional case, and the sacrifice layer is eliminated, and the connection line is used as a semiconductor substrate. By making it, there is no need to wire-bond the conversion unit and the signal processing circuit, and it is possible to make wire-less.
Further, by forming a cavity (for example, a back chamber) of the transducer device and an air passage communicating from the acoustic port to the conversion section on one second substrate , the mounting density can be improved and the cost can be reduced. There is.

FIG. 2 is a cross-sectional view (only a part of the cross-section is shown) illustrating the configuration of the transducer device according to the embodiment of the present invention. FIG. 7 is a cross-sectional view (only a part is shown in cross-section) showing a manufacturing process (ac process) of the first substrate of the transducer device of the example. FIG. 5 is a cross-sectional view (only a part is shown in cross-section) showing a manufacturing process (d-i process) of the first substrate of the transducer device of the example. FIG. 9 is a cross-sectional view (only a part is shown in cross-section) showing a manufacturing process (ad process) of the second substrate of the transducer device of the example. FIG. 9 is a cross-sectional view (only a part is shown in cross-section) showing a manufacturing process (eg, g-g process) of the second substrate of the transducer device of the example. FIG. 5 is a cross-sectional view (only a part is shown in cross-section) showing a state when the first substrate and the second substrate are joined in the transducer device of the example. FIG. 5 is a plan view showing a joint on the upper surface of the first substrate of the example. FIG. 9 is a cross-sectional view (only a part is shown in cross-section) showing a configuration of a conventional transducer device.

  FIG. 1 shows a configuration of a transducer device (microphone device or the like) according to an embodiment. In FIG. 1, reference numeral 16 denotes a first substrate made of silicon, 17 denotes a second substrate made of silicon, and 18 denotes a first substrate. A movable electrode (membrane) provided at 16 and a fixed electrode (back plate) provided at the second substrate 17 constitute a converter (transducer) by the fixed electrode 19 and the movable electrode 18. On the first substrate 16, a signal processing circuit 22, a resistor 23, a capacitor 24, and a through-hole via (through hole) connected to the movable electrode 18 by a wiring layer 21 (wiring (not shown) formed on the wiring layer 21). Electrodes 26, external terminals 27 and the like.

  In the second substrate 17, a back chamber 30, an acoustic port (entrance) 31, and an air passage (hole) 32 communicating from the acoustic port 31 to the movable electrode 18 are formed. An air passage (hole) (not shown) is formed from the air passage 32 to the movable electrode 18.

  Then, the first substrate 16 and the second substrate 17 are joined at an inner joint portion 34a and an outer joint portion 34b, whereby a transducer device packaged with a silicon substrate is manufactured. The movable electrodes 18 are arranged in parallel, and a predetermined space 100 is formed and secured between them.

  FIGS. 2 and 3 show a manufacturing process of the first substrate of the embodiment, and FIGS. 4 and 5 show a manufacturing process of the second substrate. A plurality of first substrates 16 are formed, a plurality of the second substrates 17 are formed on a second silicon wafer, and the first and second wafers are overlapped and joined to form a plurality of pieces. (Package) is manufactured, and each drawing shows the configuration of each device.

As shown in FIG. 2A, a signal processing circuit 22, a resistor 23 and a capacitor 24 are formed on a first substrate 16 made of silicon by a normal semiconductor device manufacturing process, and wiring patterns 21a and 21b are formed. Is formed. Further, the first substrate-side portion 25 of the bonding portion 34b described with reference to FIG. In the wiring layer section 21, the wiring patterns 21a and 21b are connected to the signal processing circuit 22 and the like by another wiring (not shown), and are connected to the conversion section as described later with reference to FIGS.
Next, as shown in FIG. 2B, a resist 36 is formed on the upper surface of the first substrate 16, and an opening groove 26c for a through-hole via is formed by RIE (reactive ion etching). Here, the depth of the opening groove 26c is set to be slightly deeper than the final substrate finished thickness.
FIG. 2C shows a step of embedding the opening groove 26c (a step of forming a through-hole via), and this embedding is performed by a plating embedding method or a Doped Poly-Silicon embedding method. At this stage, it is a blind via.

FIG. 3D shows a preparation process for forming the movable electrode 18. Here, a temporary base 38 and an oxide film 39 made of aluminum (Al) are formed. Next, the PAD 40 is opened to expose a part of the wiring patterns 21a and 21b.
FIG. 3E shows a step of forming the movable electrode 18. Since the high-temperature process cannot be performed since the formation of the signal processing circuit 22 has already been completed, the movable electrode 18 is basically made of a metal film such as aluminum or titanium. Or an amorphous silicon film to which a plasma impurity is added. The movable electrode 18 is connected to the wiring pattern 21a of the wiring layer 21 via the PAD 40, and is connected to the signal processing circuit 22 and the like from the wiring layer 21.
FIG. 3F shows a process of forming an insulating isolation oxide film ring necessary for insulation isolation from the second substrate 17 side, and insulates the fixed electrode 19 and the movable electrode 18 when joining with the second substrate 17. An insulating film ring 42 (see FIG. 7) is formed for separation.

3 (g) and 3 (h) show a preparation process for forming the external terminal 27. First, in FIG. 3 (g), after applying a photoresist 43, the passivation film around the chip is etched to form a bonding portion. After exposing the first substrate side portion 25 of 34b, the back grinding of the first substrate 16 is performed to form the through-hole via 26. In FIG. 3H, after removing the photoresist 43 and the temporary pedestal 38, an oxide film (or a permanent resist film) 45 is formed on the back surface of the first substrate 16, and the external terminals 27 are formed by the oxide film 45. And the substrate are separated.
FIG. 3 (i) shows an external terminal forming step, in which a metal external terminal 27 is formed below the through-hole via 26 using a plating material (solder material).

Next, the manufacture of the second substrate 17 will be described with reference to FIGS.
FIG. 4A shows a preparation process for forming an etched shape having a step by one dry etching, and shows a cross-sectional shape before etching. In this step, the second substrate 17 made of silicon is oxidized to leave an oxide film 46 at a desired position by resist patterning, and a resist pattern 47 is formed along the edge of the chip edge (peripheral end). . In the etching by the RIE method, the start of silicon etching can be delayed by the presence of the oxide film 46, and the oxide film 46 disappears as the etching proceeds. Therefore, the height of the oxide film 46 is adjusted so that the silicon protrusion 49 shown in FIG. 4B has a desired height.

  FIG. 4B shows a configuration after the silicon etching. On the lower surface of the second substrate 17, a groove having a predetermined depth leaving an edge portion 17 e is formed by the resist pattern 47 of FIG. This chip edge portion 17e becomes the original wafer surface. Normally, in a semiconductor process, a cross section is expressed with the processed surface up, but in the embodiment, the cross section is expressed with the processed surface down. Note that the lower surface side is a bonding surface with the first substrate 16. The silicon projection 49 is designed to come into contact with the insulating film ring 42 of FIG. 3 when the two substrates are joined. The oxide film 48 serves to insulate a fixed electrode 19 described later from the silicon second substrate 17.

  FIG. 4C shows a preparation process of forming the fixed electrode and the back chamber. As shown in the figure, the lower step surface of the second substrate 17 is subjected to wet etching after, for example, sputtering aluminum and performing resist patterning. The fixed electrode 19 having the acoustic hole 50 is formed by patterning the aluminum and the oxide film 48 by using the method described above. In this step of the embodiment, an aluminum film is also formed on the surface of the silicon projection 49 and the surface of the edge 17e. This is to make it function as a shield film. Further, an oxide film is formed on the upper surface of the second substrate 17, resist-patterned and etched to form an oxide film 52a, and then an oxide film is formed again, and the oxide film 52a is formed on the oxide film 52a. Further, an oxide film 52b is formed. This oxide film 52b is formed in order to control the amount of etching with a time difference. The edge of the upper surface of the second substrate 17 is located on the original surface of the silicon substrate, and is protected by the resist 53 so as not to be processed by the RIE method.

  FIG. 4D shows a processing step by the RIE method. Here, a back chamber (cavity) 30 of a cylindrical space and an air passage (hole) 32 serving as a passage of sound pressure are formed. 32 has a diameter of, for example, about 50 to 100 microns, and a plurality of the 32 are provided along the periphery of the back chamber 30. Further, by forming the oxide films 52a and 52b of FIG. 4C, a part of the second substrate 17 can be left so as to support the silicon protrusion 49 as shown in FIG. it can.

Next, in FIG. 5E, the handle wafer 55 is attached to the end surface of the lower surface side edge portion 17e of the second substrate 17 in FIG. 4D.
In FIG. 5F, a silicon lid 56 having a hole 31a serving as an acoustic port (sound pressure inlet) 31, which is an inlet of the air passage 32 formed in FIG. 4D, is attached. The hole 31 a of the silicon lid 56 is designed to coincide with the position of the air passage 32.
In FIG. 5 (g), the upper portion of the silicon lid 56 is cut by back grinding so as to cut out the hole 31a serving as the acoustic port 31 so as not to penetrate, and thereafter, is etched by dry etching until the hole just passes. Thus, the acoustic port 31 is formed.

  FIG. 6 shows a state in which the first substrate 16 and the second substrate 17 are bonded, and FIG. 7 shows a position of a bonding portion of the first substrate 16. In 16, the first substrate-side portion 25 of the bonding portion 34 b is formed along the periphery of the substrate, and the insulating film ring 42 is formed along the periphery of the movable electrode 18.

  On the other hand, as described above, the bonding material (for example, gold: Au) 58 is attached to the tip aluminum film of the silicon protrusion 49 of the second substrate 17, and the bonding material (for example, gold) is attached to the tip aluminum film of the peripheral edge portion 17e. 59, the insulating film ring 42 and the silicon protrusion 49 (the distal end aluminum film) are joined via a joining material 58 (joining portion 34a), and the first substrate side portion 25 is joined with the joining material 59. The first substrate 16 and the second substrate 17 are bonded to each other by bonding (the bonding portion 34b) the edge portion 17e (a distal end aluminum film thereof). This bonding can be performed using a resin film instead of a metal such as gold (Au).

  When the first substrate 16 and the second substrate 17 are joined in this way, as shown in FIG. 1, the movable electrode 18 and the fixed electrode 19 of the conversion unit are arranged in parallel, and between these electrodes. A predetermined space 100 is formed, and in the apparatus, the movable electrode 18 fluctuates due to sound pressure, and a change in capacitance via the space 100 is captured as an electric signal. The signal from the conversion unit is subjected to processing such as amplification in the signal processing circuit 22.

  In the manufacture of the above-described transducer device, bonding at a wafer level is performed, and a wafer on which a plurality of first substrates 16 are formed and a wafer on which a plurality of second substrates 17 are formed as shown in FIG. Then, by joining and joining, a large number of transducer devices (packages) can be obtained.

  In the above embodiment, the movable electrode 18 is provided on the first substrate 16 and the fixed electrode 19 is provided on the second substrate 17. On the contrary, the fixed electrode 19 is provided on the first substrate 16 and the movable electrode 18 is provided on the second substrate 17. May be provided, and the signal processing circuit 22, the back chamber 30, the acoustic port 31 and the like may be arranged on the substrate on the opposite side of the embodiment, and these components are designed in various arrangements. It is possible to

As described above, in the embodiment, two wafers or substrates (16, 17) using silicon are stacked and packaged by bonding at a chip scale, and further, the conversion unit (18, 19) and the signal processing circuit 22 Are arranged side by side in the vertical direction, so that the production can be facilitated and the size can be reduced, and the temperature use range can be widened.
In addition, by connecting the conversion units (18, 19) and the signal processing circuit 22 via the wiring layer unit 21, bonding wireless is realized, and the first substrate 16 and the second substrate 17 are bonded to each other to form a space 100 of the conversion unit. Since it is formed, the sacrifice layer is not required.
Furthermore, since the back chamber 30, the acoustic port 31, and the air passage 32 are collectively formed on the second substrate 17, there is an advantage that the mounting density can be improved and the cost can be reduced.

1, 19: fixed electrode, 2, 18: movable electrode,
3, a conversion unit, 4, 22, a signal processing circuit,
13 ... Back chamber,
16 ... first substrate, 17 ... second substrate,
17e: edge portion, 21: wiring layer portion,
25 ... the first substrate-side portion of the joint portion 34b;
26: through-hole via, 27: external terminal,
30 ... back chamber (cavity),
31 ... acoustic port, 32 ... air passage,
34a, 34b ... joint, 42 ... insulating film ring,
49: silicon projection, 100: space.

Claims (3)

A first substrate on which a movable electrode of a converter, an insulating film ring, a wiring layer, and a signal processing circuit connected to the converter via the wiring layer are formed;
A fixed electrode of the conversion unit, a projection abutting on the insulating film ring, and a cavity that is disposed inside and communicates with the fixed electrode are formed, and a peripheral portion of the cavity communicates from an acoustic port to the conversion unit. A second substrate having an air passage formed therein;
While securing a predetermined space between the fixed electrode and the movable electrode and arranging the two electrodes in parallel, the insulating film ring and the protruding portion are in contact with each other, and the air passage is formed in the movable electrode of the movable electrode. A transducer device formed by joining the first substrate and the second substrate so as to communicate with one substrate. Forming a plurality of first substrates having a signal processing circuit connected to the conversion unit via the movable electrode, the insulating film ring, the wiring layer, and the wiring layer of the conversion unit on the first wafer;
A fixed electrode of the conversion section, a projection abutting on the insulating film ring, a cavity communicated with the fixed electrode and disposed inside, and air disposed around the cavity and communicating from an acoustic port to the conversion section. Forming a plurality of second substrates having passages in a second wafer;
While securing a predetermined space between the movable electrode of each of the plurality of first substrates and the fixed electrode of each of the plurality of second substrates, and arranging both electrodes in parallel, the plurality of Each of the insulating film rings of one substrate abuts on each of the protrusions of each of the plurality of second substrates, and the air passage of each of the plurality of second substrates is connected to the movable portion of each of the plurality of first substrates. The first wafer and the second wafer are overlapped and joined so as to communicate with the electrode on the first substrate side,
A method for manufacturing a transducer device, wherein the bonded first and second wafers are singulated and manufactured. The signal processing circuit is provided at a position in the longitudinal direction of the first substrate of the first wafer that is aligned with the conversion unit, and the signal processing circuit and the conversion unit are connected by a wiring layer. 3. The method for manufacturing the transducer device according to 2 .

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