Method for manufacturing semiconductor device and method for manufacturing microphone

A method for manufacturing a semiconductor device is provided, the method comprising: fabricating a semiconductor element on a semiconductor substrate; joining a surface of the semiconductor substrate to a support member, the surface being on a side where the semiconductor element is fabricated; and polishing a surface on an opposite side of the surface of the semiconductor substrate where the semiconductor element is fabricated and reducing a thickness of the semiconductor substrate, in a state where the semiconductor substrate and the support member are joined.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of priority from Japanese Patent Application No. 2011-035915, filed on 22 Feb. 2011, and International Application No. PCT/JP2011/056586, filed on 18 Mar. 2011 and designating the United States, the entire contents of which is incorporated herein by reference for all purposes.

BACKGROUND

The present invention relates to a method for manufacturing a semiconductor device. The present invention also relates to a method for manufacturing a microphone having an acoustic sensor mounted in a package.

FIG. 1is a cross-sectional view of a conventional microphone having a general structure. A microphone11has an acoustic sensor15and a signal processing circuit17mounted in a package formed from a cover12and a circuit board13. The acoustic sensor15and the signal processing circuit17are mounted being arranged side by side on the upper surface of the circuit board13. The signal processing circuit17is covered by sealing resin21. The acoustic sensor15and the signal processing circuit17are electrically connected by a bonding wire18, and the signal processing circuit17is further connected to a board wiring14of the circuit board13by a bonding wire19.

Normally, the lower surface of the circuit board13is mounted on a printed wiring board, and is adhered to the printed wiring board. Accordingly, a sound introduction hole20for introducing acoustic vibration into the package is opened in the upper surface of the cover12. The lower surface of the acoustic sensor15is bonded to the circuit board13, and the lower surface of a back chamber16is blocked by the circuit board13.

In a capacitance microphone, there is a correlation between the sensitivity of the microphone and the capacity of the back chamber, and the sensitivity of the microphone decreases as the capacity of the back chamber decreases. In the microphone11, since the sound introduction hole20is provided to the cover12, and the space between the acoustic sensor15and the circuit board13forms the back chamber16, the capacity of the back chamber16cannot be increased, and it is difficult to improve the sensitivity of the microphone11.

(Microphone of Patent Document 1)

A microphone disclosed in Patent Document 1 (JP 2007-178221 A) is shown inFIG. 2. In a microphone31of Patent Document 1, the signal processing circuit17is mounted on the upper surface of the circuit board13. A spacer32is fixed to the upper surface of the circuit board13, at a position adjacent to the signal processing circuit17, and the acoustic sensor15is further mounted on the upper surface of the spacer32. A vertically penetrating through-hole33is opened in the spacer32. An electrode pad is provided to the lower surface of the acoustic sensor15, and the acoustic sensor15is electrically connected to the circuit board13via the spacer32. The sound introduction hole20is opened in the cover12.

In the microphone31, the through-hole33of the spacer32is continuous with the back chamber16of the acoustic sensor15, and thus, the space below a diaphragm is widened. As a result, the capacity of the back chamber16of the acoustic sensor15can be substantially increased, and the sensitivity of the microphone31is improved.

However, according to such a structure, since the spacer32is mounted on the upper surface of the circuit board13, and the acoustic sensor15is further mounted on the spacer32, there is an inconvenience that the height of the microphone31is great.

As a method for reducing the height of such a microphone, there is conceivable a method for reducing the height of the acoustic sensor by polishing and thinning the substrate portion of the acoustic sensor in the manufacturing process of the acoustic sensor. However, in the manufacturing process of the acoustic sensor, a plurality of acoustic sensors is fabricated at one time on a wafer. Accordingly, if the substrate portion of the acoustic sensor is to be made thin, the wafer is to be polished and thinned during the manufacturing process of the acoustic sensor.

As the wafer, a thin wafer with a large diameter is usually used. Accordingly, if the wafer is polished and made even thinner, rigidity of the wafer is greatly reduced. As a result, the wafer may be cracked or chipped in the polishing process or a subsequent process, and a yield of the acoustic sensor may be reduced.

The present invention has been devised to solve the problems described above, and an object thereof is to provide a method for manufacturing a semiconductor device structured to have a semiconductor element mounted on a support member (for example, a microphone structured to have an acoustic sensor mounted on a support member), the method being capable of reducing the height of the semiconductor element, and thereby reducing the height of the semiconductor device.

SUMMARY

A method for manufacturing a semiconductor device according to at least one embodiment of the present invention comprising: fabricating a semiconductor element on a semiconductor substrate; joining a surface of the semiconductor substrate to a support member, the surface being on a side where the semiconductor element is fabricated; and polishing a surface on an opposite side of the surface of the semiconductor substrate where the semiconductor element is fabricated and reducing a thickness of the semiconductor substrate, in a state where the semiconductor substrate and the support member are joined.

DETAILED DESCRIPTION

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the following embodiments, a microphone is described as an example of a semiconductor device. In this microphone, an acoustic sensor is used as a semiconductor element. However, the present invention is not restricted to the following embodiments, and various modifications in design can be made without departing from the scope of the present invention.

First Embodiment

Hereinafter, a microphone (i.e., a semiconductor device) according to a first embodiment of the present invention will be described with reference toFIGS. 3 to 5(B).FIG. 3is a cross-sectional view showing a structure of a microphone41according to the first embodiment.FIG. 4(A)is a perspective view of an interposer52(i.e., a support member) used for the microphone41, andFIG. 4(B)is a perspective view of the interposer52where the interposer52is vertically inverted.FIGS. 5(A) and 5(B)are cross-sectional views of the interposer52, andFIG. 5(A)shows a cross-section along line X-X inFIG. 4(A), andFIG. 5(B)shows a cross-section along line Y-Y inFIG. 4(A).

In the microphone41, a package is formed by a cover42and a circuit board43. An acoustic sensor51(i.e., a semiconductor element), the interposer52, and a signal processing circuit53are accommodated inside the package.

A plurality of upper surface electrode pads44aand44bfor joining the interposer52and the signal processing circuit53are provided on the upper surface of the circuit board43forming a part of the package. A plurality of lower surface electrode pads45for connecting the microphone41to a printed wiring board or the like at the time of mounting the microphone41on the printed wiring board or the like are provided on the lower surface of the circuit board43. The cover42is box-shaped with its lower surface opened, and an electromagnetic shield film47, which is a metal-coated film, is formed on the inner surface of a cover main body46formed of an insulating material (for example, plastic). Also, at least one sound introduction hole48is opened in the cover42to introduce acoustic vibration into the package.

Note that the cover main body46may be made of metal, and in this case, the cover main body46serves as an electromagnetic shied. Thus, the electromagnetic shield film47is not required to be separately provided.

The acoustic sensor51is a capacitance element fabricated using a MEMS technique. As shown inFIG. 3, the whole of the acoustic sensor51is held by a silicon substrate54(a semiconductor substrate). A front chamber55is opened in the silicon substrate54in a vertically penetrating manner. A thin-film diaphragm56is provided on the lower surface of the silicon substrate54so as to cover the opening on the lower surface of the front chamber55. The diaphragm56is formed of conductive polysilicon. Accordingly, the diaphragm56itself is a movable electrode plate. The diaphragm56is stretched like a film on the lower surface of the silicon substrate54by being supported by anchors (not shown) at several positions of the outer peripheral edge. Among the anchors, a vent hole (a narrow gap) is formed between the outer peripheral edge of the diaphragm56and the lower surface of the silicon substrate54.

A back plate57is provided below the diaphragm56such that an air gap58(a void) is formed between the back plate57and the diaphragm56, and an outer peripheral portion of the back plate57is fixed to the lower surface of the silicon substrate54. A fixed electrode plate59is provided on the upper surface of the back plate57so as to face the diaphragm56. The back plate57is formed of insulating SiN, and the fixed electrode plate59is formed of conductive polysilicon. As a result, a capacitor for acoustic vibration detection is formed by the diaphragm56and the fixed electrode plate59that face each other across the air gap58.

A large number of acoustic holes60(acoustic perforations) are provided to substantially the entire back plate57and fixed electrode plate59so as to allow acoustic vibration that has vibrated the diaphragm56to pass through.

An extraction wiring61extends from an end portion of the diaphragm56. An electrode portion62embedded in the back plate57is electrically connected to an end portion of the extraction wiring61. An extraction wiring63extends from an end portion of the fixed electrode plate59. An electrode portion64embedded in the back plate57is electrically connected to an end portion of the extraction wiring63. The lower surface of the electrode portion62is exposed at one of four corners of the lower surface of the acoustic sensor51, and a bump67is provided on the lower surface of the electrode portion62. The lower surface of the electrode portion64is exposed at another corner of the four corners of the lower surface of the acoustic sensor51, and a bump67is provided on the lower surface of the electrode portion64. Of the four corners of the lower surface of the acoustic sensor51, dummy electrodes (not shown) are provided at corners where the electrode portions62and64are not provided. The dummy electrode is an electrode for mechanically fixing the lower surface of the acoustic sensor51by soldering or the like, and does not have an electrical function. The bump is also provided for the dummy electrode.

The interposer52has a structure as shown inFIGS. 4(A),4(B),5(A) and5(B). The interposer52is formed of an insulating material, particularly, a semiconductor substrate, into a rectangular tube shape, and a cavity70vertically penetrates the interposer52to accommodate the signal processing circuit53. A ventilation notch71(i.e., an acoustic transmission path) is formed in an upper portion of a wall surface of the interposer52.

The interposer52includes a structure for electrically connecting the acoustic sensor51and the circuit board43. That is, a penetrating electrode65(a conductor) is embedded in one of four corners of the interposer52, and a pad portion65aelectrically connected to the penetrating electrode65is provided on the upper surface of the interposer52, and a pad portion65belectrically connected to the penetrating electrode65is provided on the lower surface thereof.

A penetrating electrode66(a conductor) is embedded in another corner of the four corners of the interposer52, and a pad portion66aelectrically connected to the penetrating electrode66is provided on the upper surface of the interposer52, and a pad portion66belectrically connected to the penetrating electrode66is provided on the lower surface thereof. Moreover, of the four corners of the interposer52, at corners where the penetrating electrodes65and66are not provided, dummy electrodes72aare provided on the upper surface of the interposer52, and dummy electrodes72bare provided on the lower surface thereof. The dummy electrodes72aand72bare electrodes for mechanically connecting and fixing the interposer52, and the dummy electrode72aon the upper surface and the dummy electrode72bon the lower surface are not electrically connected to each other.

The ventilation notch71is formed to an upper portion of the wall surface of the interposer52inFIGS. 4(A),4(B),5(A), and5(B), but the ventilation notch71may be formed in a lower portion of the wall surface of the interposer52. Also, a ventilation opening, as an acoustic transmission path, may be opened in the shape of a window in the wall surface of the interposer52. However, the acoustic transmission path such as the ventilation notch or the ventilation opening is required to have a path sectional area large enough to transfer a dynamic pressure change caused by acoustic vibration.

The signal processing circuit53(ASIC) is a circuit for amplifying an acoustic detection signal output from the acoustic sensor51, further converting the signal into a digital signal, and outputting the signal. An electrode portion69for inputting a signal from the acoustic sensor51and an electrode portion69for outputting a signal which has been signal-processed are provided on the lower surface of the signal processing circuit53.

The microphone41is assembled in the following manner. The acoustic sensor51is placed on the interposer52, and the bump67provided on the lower surface of the electrode portion62is joined to the upper surface (the pad portion65a) of the penetrating electrode65, and the bump67provided on the lower surface of the electrode portion64is joined to the upper surface (the pad portion66a) of the penetrating electrode66. Also, the bump67of the dummy electrode provided on the lower surface of the acoustic sensor51is joined to the dummy electrode72aon the upper surface of the interposer52. As a result, the acoustic sensor51is mechanically fixed to the upper surface of the interposer52by the bumps67at four positions. Moreover, the electrode portions62and64of the acoustic sensor51are electrically connected to the lower surface (the pad portions65band66b) of the interposer52through the penetrating electrodes65and66.

The pad portions65band66b, and the dummy electrode72bprovided on the lower surface of the interposer52are each joined to the upper surface electrode pad44aof the circuit board43by a conductive material68such as solder or a conductive adhesive. The electrode portion69of the signal processing circuit53is also joined to the upper surface electrode pad44bof the circuit board43by the conductive material68such as solder or a conductive adhesive.

The cover42is placed on the upper surface of the circuit board43so as to cover the acoustic sensor51, the interposer52, and the signal processing circuit53which are mounted on the upper surface of the circuit board43. At this time, the sound introduction hole48of the cover42is arranged so as to border the front chamber55of the acoustic sensor51. The entire circumference of the upper surface of the acoustic sensor51(the upper surface of the silicon substrate54) is bonded and sealed to the inner surface of the cover42by adhesive resin50. The lower surface of the cover42is bonded to the upper surface of the circuit board43by a conductive adhesive, and the electromagnetic shield film47is electrically connected to a ground electrode of the circuit board43.

When acoustic vibration enters the microphone41from the sound introduction hole48, the acoustic vibration is guided into the front chamber55of the acoustic sensor51. Since the acoustic vibration vibrates the diaphragm56, capacitance of the capacitor formed from the diaphragm56and the fixed electrode plate59is changed, and this change in the capacitance is output as acoustic detection signals from the electrode portions62and64.

The acoustic detection signals output from the acoustic sensor51are transmitted to the upper surface electrode pads44athrough the penetrating electrodes65and66. The upper surface electrode pads44ato which the pad portions65band66bof the penetrating electrodes65and66are joined are electrically connected to the upper surface electrode pad44bto which the electrode portion69for signal input of the signal processing circuit53is joined by a wiring pattern (not shown) provided on the upper surface or the inside of the circuit board43. Accordingly, the acoustic detection signals of the acoustic sensor51are input from the electrode portion69for signal input to the signal processing circuit53. The upper surface electrode pad44bto which the electrode portion69for signal output is joined is connected to the lower surface electrode pad45of the circuit board43by a wiring structure (not shown) provided inside the circuit board43. Accordingly, an output signal processed by the signal processing circuit53is output to the outside from the lower surface electrode pad45of the circuit board43.

Note that, since the mode of electrical connection between the acoustic sensor51and the signal processing circuit53, and the number of penetrating electrodes of the interposer52varies according to the structures of the acoustic sensor51and the signal processing circuit53, the description above is only an example.

The following effects can be achieved by the acoustic sensor51structured in the above manner. In the case of connecting the acoustic sensor and the signal processing circuit using a bonding wire (for example, seeFIG. 1), the bonding wire may break due to vibration or the like if the bonding wire is tightly stretched. Also, if the bonding wire is arranged being slackened downward, the wire may come in contact with the electrode pad of the acoustic sensor or the signal processing circuit. Accordingly, the bonding wire is arranged being slackened upward. As a result, the height of the package is required to be high enough to accommodate the bonding wire protruding upward, and the height of the microphone is increased to that extent.

In contrast, in the acoustic sensor51of the present embodiment, the acoustic sensor51and the signal processing circuit53are connected through the penetrating electrodes65and66provided to the interposer52. Accordingly, the slackening of the bonding wire does not have to be taken into account as in the case of using the bonding wire for connection, and the height of the acoustic sensor51is not unnecessarily increased.

Also, since the acoustic sensor51and the signal processing circuit53are vertically arranged, an area for mounting the signal processing circuit53may not be provided separately with the area for mounting the acoustic sensor51. Thus, as compared to a conventional case of arranging the acoustic sensor51and the signal processing circuit53side by side, the plane area of the microphone41can be made significantly smaller. Therefore, even if the sizes of the acoustic sensor51and the signal processing circuit53cannot be made small, the microphone41can be miniaturized.

In the acoustic sensor51, the space surrounded by the silicon substrate54between the sound introduction hole48and the diaphragm56forms the front chamber55. On the other hand, the space on the side of the lower surface of the diaphragm56forms the back chamber of the acoustic sensor51. However, acoustic vibration which has passed the diaphragm56can pass through the acoustic hole60and spread in the cavity70inside the interposer52, and then, can further pass through the ventilation notch71and spread in an intra-package space49. Here, of the space inside the package surrounded by the cover42and the circuit board43, the intra-package space49is a space outside the acoustic sensor51and the interposer52. Thus, in the acoustic sensor51, the space inside the acoustic sensor51and below the diaphragm56, the cavity70inside the interposer52, and the intra-package space49substantially form the back chamber. That is, in the microphone41, substantially all the space inside the package, except for the front chamber55, forms the back chamber.

The sensitivity of the acoustic sensor51is improved as the capacity of the back chamber is increased. In the microphone41, since a large part of the space inside the package can be used as the back chamber, the sensitivity of the acoustic sensor51can be improved.

Also, in the microphone41of the present embodiment, since the electromagnetic shield film47is formed on the inner surface of the cover42(the electromagnetic shield may also be provided inside the circuit board43), the acoustic sensor51and the signal processing circuit53can be shut off from external noise, and the S/N ratio of the microphone41can be improved.

(Method for Manufacturing Microphone of First Embodiment)

Next, a process of manufacturing the microphone41of the first embodiment will be described based onFIGS. 6(A) to 11(B). A plurality of interposers52are fabricated at one time by the process as shown inFIGS. 6(A) to 6(F).FIG. 7(A)is a plan view showing the plurality of interposers52that are integrally fabricated as a result.FIG. 7(B)shows a cross section along line Z-Z inFIG. 7(A). The plurality of interposers52are fabricated in the following manner.

FIG. 6(A)shows an insulating Si wafer73used for fabricating a plurality of interposers52at one time. A thin metal film is formed on the lower surface of the Si wafer73, and the thin metal film is subjected to patterning by photolithography or the like. As a result, as shown inFIG. 6(B), the pad portions65b,66b, and72b(not shown) are formed at respective predetermined positions on the lower surface of the Si wafer73. Then, as shown inFIG. 6(C), through-holes76are opened above the pad portions65band66bby etching the Si wafer73. The through-holes76are filled with a metal material by coating or the like, and as shown inFIG. 6(D), the penetrating electrodes65and66are formed inside the through-holes76. The penetrating electrode65is formed on the pad portion65b, and is electrically connected to the pad portion65b. Similarly, the penetrating electrode66is formed on the pad portion66b, and is electrically connected to the pad portion66b. Moreover, a thin metal film is formed on the upper surface of the Si wafer73, and the thin metal film is subjected to patterning by photolithography or the like. As a result, as shown inFIG. 6(E), the pad portion65belectrically connected to the penetrating electrode65is formed on the penetrating electrode65, and the pad portion66belectrically connected to the penetrating electrode66is formed on the penetrating electrode66. Moreover, on the upper surface of the Si wafer73, the dummy electrode72ais formed at a position facing the dummy electrode72b. Then, a center portion of a region surrounded by a set of pad portions65aand66aand the dummy electrode72a(not shown) is etched, and as shown inFIG. 6(F), the vertically penetrating cavity70is opened. Lastly, the ventilation notch71is formed by etching the upper surface of the Si wafer73in the shape of a groove, and a plurality of interposers52that are integrated are fabricated. A plurality of interposers52are thus fabricated, as shown inFIGS. 7(A) and 7(B).

A plurality of acoustic sensors51are also fabricated at one time.FIG. 8(A)is a cross-sectional view showing a plurality of acoustic sensors51which have been fabricated at one time. The polysilicon diaphragm56is provided on the upper surface of an Si wafer74(a plate), at each region which is to be the acoustic sensor51. A sacrifice layer75is formed on the diaphragm56, and the fixed electrode plate59and the back plate57are provided on the upper surface of the sacrifice layer75. The electrode portions62and64and dummy electrodes are provided at corners of the region which is to be the acoustic sensor51.

As shown inFIG. 8(B), the acoustic sensor51fabricated as shown inFIG. 8(A)is vertically inverted and stacked on the upper surface of the interposer52inFIG. 7, and the electrode portion62and the pad portion65a, the electrode portion64and the pad portion66a, and the dummy electrode and the dummy electrode72aare joined by the bumps67. As a result, the Si wafer74on which a plurality of acoustic sensors51are arranged, and the Si wafer73on which a plurality of interposers52are arranged are integrally bonded to each other.

Next, as shown inFIG. 9(A), the upper surface of the acoustic sensor51is polished, and the thickness of the Si wafer74is reduced. Since the wafer is thin and is substantially disc-shaped with a large diameter, its rigidity is not very high. Accordingly, if the Si wafer74where the acoustic sensor51is formed is singly polished to reduce the thickness of the Si wafer74, the Si wafer74may be cracked or chipped in the polishing process or in a subsequent process, and the yield of the acoustic sensor51is reduced. However, according to the manufacturing method described here, since two Si wafers, i.e., the Si wafer73and the Si wafer74, are bonded together, the rigidity of the wafer can be increased. Accordingly, by performing polishing after bonding the Si wafer74and the Si wafer73together, polishing can be performed while increasing the rigidity of the Si wafer74, and the Si wafer74can be polished easily while achieving a high yield.

Subsequently, as shown inFIG. 9(B), the sacrifice layer75of the acoustic sensor51is removed by etching, and the air gap58is formed between the diaphragm56and the fixed electrode plate59. As a result, the diaphragm56is formed into a film capable of vibrating. Then, the Si wafers74and73are diced along a cutting line shown by a dashed line inFIG. 9(B). As a result, as shown inFIG. 10(A), the acoustic sensors51and the interposers52are separated one by one while being vertically joined.

Next, the signal processing circuit53is flip-chip mounted on the upper surface of the circuit board43, and the electrode portion69of the signal processing circuit53is joined to the upper surface electrode pad44bof the circuit board43by the conductive material68. The signal processing circuit53mounted on the circuit board43in this manner is shown inFIG. 10(B).

Next, as shown inFIG. 11(A), the interposer52and the acoustic sensor51that are integrated are overlapped on the circuit board43to cover the signal processing circuit53, and the signal processing circuit53is accommodated in the cavity70of the interposer52. At this time, the pad portions65band66band the dummy electrode72bof the interposer52are each joined to the upper surface electrode pad44aof the circuit board43by the conductive material68.

Subsequently, as shown inFIG. 11(B), the cover42is overlapped on the circuit board43so as to cover the acoustic sensor51, the interposer52, and the signal processing circuit53. The sound introduction hole48is opened in the cover42in advance, and the sound introduction hole48overlaps the upper surface opening of the front chamber55when the cover42is overlapped on the circuit board43. Then, the lower surface of the cover42is joined to the circuit board43by a conductive adhesive. At this time, the upper surface of the acoustic sensor51is bonded to the inner surface of the cover42by the adhesive resin50, and the entire circumference of the upper surface of the acoustic sensor51and the entire circumference of the sound introduction hole48on the inside of the cover42are sealed, and the acoustic vibration entering from the sound introduction hole48is prevented from leaking from the gap between the acoustic sensor51and the cover42.

When the microphone41is manufactured in this manner, the Si wafer74is unlikely to be cracked or chipped at the time of polishing of the Si wafer74, and the yield in the manufacturing process of the microphone41is increased. Also, since the Si wafer74is not easily cracked or chipped, the thickness of the Si wafer74can be reduced by polishing, and the height of the acoustic sensor51can be reduced. If it is possible to reduce the height of the acoustic sensor51, the cover42with a small height can be used, and the microphone41can be reduced in height and size.

Second Embodiment

FIG. 12is a cross-sectional view showing a microphone81according to a second embodiment of the present invention. The microphone81is different from the microphone41of the first embodiment only in the form of the interposer52. Accordingly, with respect to the microphone81of the second embodiment, description of other than the interposer52is omitted.

As shown inFIGS. 13(A) and 13(B), in the interposer52used for the microphone81, the cavity70for accommodating the signal processing circuit53is formed into a box shape which is open on the bottom and which is closed on the top. On the other hand, one or more groove-shaped ventilation notches71are provided on the upper surface of the interposer52.

Accordingly, the space (the back chamber) below the diaphragm56of the acoustic sensor51communicates with the intra-package space49through the ventilation notch71, and not through the cavity70for accommodating the signal processing circuit53. Accordingly, the capacity of the back chamber can be substantially increased, and the sensitivity of the microphone81can be improved.

In the microphone81, the cavity70of the interposer52is a space for accommodating the signal processing circuit53. Furthermore, the acoustic sensor51and the signal processing circuit53being vertically arranged are partitioned by the interposer52, and short-circuiting or the like between the acoustic sensor51and the signal processing circuit53can be prevented. Moreover, since the signal processing circuit53is covered by the interposer52, the signal processing circuit53can be protected from moisture and dust entering from the sound introduction hole48.

The microphone81of the second embodiment as described above can be manufactured in the same manner as the manufacturing method described in the first embodiment, and the height of the microphone81can be reduced.

Third Embodiment

FIG. 14is a cross-sectional view showing a microphone82according to a third embodiment of the present invention. In the microphone82, the signal processing circuit53is not placed inside the interposer52. The signal processing circuit53is mounted on the upper surface of the circuit board43, next to the interposer52. Accordingly, in the microphone82, the cavity70inside the interposer52communicates with the back chamber of the acoustic sensor51, and serves to increase the capacity of the back chamber.

The microphone82of the third embodiment as described above may be manufactured in the same manner as the manufacturing method described in the first embodiment, and the height of the microphone82can be reduced.

Furthermore, the interposer52does not necessarily include an acoustic transmission path such as the ventilation notch71. The interposer52as shown inFIG. 15that does not include the ventilation notch71may also be used. In this case, the back chamber is extended only to the cavity70inside the interposer52, and the intra-package space49cannot be used as the back chamber. However, an acoustic transmission path such as the ventilation notch71to the interposer52may not be provided to the manufacturing method of the present invention.

Other Embodiments

The interposer52may have various structures other than the structures described in the first and second embodiments.FIGS. 16(A) and 16(B)show yet another embodiment. In the interposer52, an extended electrode portion83ais extended from the pad portion65aalong the upper surface of the interposer52, an extended electrode portion83bis extended from the pad portion65balong the lower surface of the interposer52, and a tip end portion of the extended electrode portion83aand a tip end portion of the extended electrode portion83bare connected by the penetrating electrode65. Similarly, an extended electrode portion84ais extended from the pad portion66aalong the upper surface of the interposer52, and an extended electrode portion84bis extended from the pad portion66balong the lower surface of the interposer52, and a tip end portion of the extended electrode portion84aand a tip end portion of the extended electrode portion84bare connected by the penetrating electrode66. According to this embodiment, the positions where the penetrating electrodes65and66are to be provided are not restricted.

Disclosed is a method for manufacturing a semiconductor device, the method comprising: fabricating a semiconductor element on a semiconductor substrate; joining a surface of the semiconductor substrate to a support member, the surface being on a side where the semiconductor element is fabricated; and polishing a surface on an opposite side of the surface of the semiconductor substrate where the semiconductor element is fabricated and reducing a thickness of the semiconductor substrate, in a state where the semiconductor substrate and the support member are joined.

With the method for manufacturing a semiconductor device according to at least one embodiment of the present invention, the semiconductor substrate on which the semiconductor element is fabricated is bonded to the support member, and then, the semiconductor substrate is polished and the thickness of the semiconductor substrate is reduced in a state where the semiconductor substrate and the support member are joined together. Accordingly, the height of the semiconductor element fabricated on the semiconductor substrate can be reduced, and the height of the semiconductor device can be reduced. Moreover, the semiconductor substrate can be polished in a state where the rigidity of the semiconductor substrate has been increased by bonding the semiconductor substrate and the support member together. Thus, the semiconductor substrate is not easily cracked or chipped in the polishing process or a process subsequent to the polishing, and the yield of the semiconductor element can be increased, and also, the height of the semiconductor device can be substantially reduced.

With the method for manufacturing a semiconductor device according to one embodiment of the present invention, the support member may be mounted on a circuit board, and a conductor for electrically connecting the semiconductor element and the circuit board may vertically penetrate the support member. According to such an embodiment, the height of the semiconductor device can be reduced compared to a case of using a bonding wire to connect the semiconductor element to the circuit board.

With the method for manufacturing a semiconductor device according to another embodiment of the present invention, the semiconductor substrate may be a wafer on which a plurality of the semiconductor elements are fabricated, and a plurality of the support members may be formed by another wafer. According to such an embodiment, a plurality of semiconductor elements and support members may be fabricated at one time, and the manufacturing efficiency of the semiconductor device is improved. Also, in this case, thin wafers with large diameters are used for the semiconductor substrate and the support member, but even in this case, according to the method of the present invention, the wafers are not easily cracked or chipped due to polishing. The usefulness of the present invention is thus further increased.

Disclosed is a method for manufacturing a microphone, the method comprising: fabricating an acoustic sensor on a semiconductor substrate; forming a cavity in a plate and fabricating a support member; joining a surface of the semiconductor substrate to the support member, the surface being on a side where the acoustic sensor is fabricated; polishing a surface on an opposite side of the surface of the semiconductor substrate where the acoustic sensor is fabricated and reducing a thickness of the semiconductor substrate, in a state where the semiconductor substrate and the support member are joined; and mounting the acoustic sensor formed on the semiconductor substrate after a polishing process, the support member, and a signal processing circuit inside a package.

With the method for manufacturing a microphone according to at least one embodiment of the present invention, the semiconductor substrate on which the acoustic sensor is fabricated is bonded to the plate which is the support member, and then, the semiconductor substrate is polished and the thickness of the semiconductor substrate is reduced in a state where the semiconductor substrate and the support member are joined together. Accordingly, the height of the acoustic sensor fabricated on the semiconductor substrate can be reduced, and the height of the microphone can be reduced. Moreover, the semiconductor substrate can be polished in a state where the rigidity of the semiconductor substrate has been increased by bonding together the semiconductor substrate and the support member. Thus, the semiconductor substrate is not easily cracked or chipped in the polishing process or a process subsequent to the polishing, and the yield of the acoustic sensor can be increased, and also, the height of the acoustic sensor can be substantially reduced.

With the method for manufacturing a microphone according to one embodiment of the present invention, the cavity may be a space for accommodating the signal processing circuit. According to such an embodiment, the plane area of the microphone can be made smaller by accommodating the signal processing circuit in the cavity of the support member, and the microphone can be miniaturized.

With the method for manufacturing a microphone according to another embodiment of the present invention, the cavity may be a space that communicates with a back chamber of the acoustic sensor. According to such an embodiment, the capacity of the back chamber of the acoustic sensor can be substantially increased, and the sensitivity of the acoustic sensor is improved.

With the method for manufacturing a microphone according to yet another embodiment of the present invention, a conductor for electrically connecting the acoustic sensor and an electrode pad provided to the package may vertically penetrate the support member. According to such an embodiment, the height of the microphone can be reduced compared to a case of using a bonding wire to connect the acoustic sensor to the package.

With the method for manufacturing a microphone according to still another embodiment of the present invention, the plate is another semiconductor substrate. If the semiconductor substrate is used as the plate of the support member, the support member can be processed using an MEMS technique or photolithography in the same manner as the acoustic sensor.

With the method for manufacturing a microphone according to yet another embodiment of the present invention, the semiconductor substrate is a wafer on which a plurality of the acoustic sensors are fabricated, and the plate is a wafer on which a plurality of the support members are fabricated. According to such an embodiment, a plurality of acoustic sensors and support members can be fabricated at one time, and the manufacturing efficiency of the microphone is improved. Also, in this case, thin wafers with large diameters are used for the semiconductor substrate and the plate, but even in this case, according to the method of the present invention, the wafers are not easily cracked or chipped due to polishing. The usefulness of the present invention is thus further increased.

Note that the means for solving the problems according to the present invention has features where the structural elements described above are combined as appropriate, and the present invention allows a large number of variations by combination of such structural elements.