JP4893123B2 - Semiconductor pressure sensor and manufacturing method thereof - Google Patents

Description

  The present invention relates to a semiconductor pressure sensor having a sensing part in which a pedestal is joined to the surface of a semiconductor chip on which an element for pressure detection is formed, and a method for manufacturing the same.

  Conventionally, Patent Document 1 proposes a pressure sensor in which a base is joined to the surface of a semiconductor chip on which an element for pressure detection is formed. In this pressure sensor, a strain gauge is formed on the front surface side of the semiconductor chip, and a recess is formed on the back surface side to form a diaphragm in which the semiconductor chip is partially thinned. By joining, a structure including a sensing unit is formed.

With such a structure, (1) the strain gauge can ensure high reliability without touching the measurement medium, and (2) a high pressure resistance can be realized because the stress applied to the surface of the semiconductor chip is compressed, 3) Since the sensing unit can be inserted into the measurement medium, the temperature measurement can be enjoyed.
Japanese Patent No. 2792116

  However, in the semiconductor pressure sensor disclosed in Patent Document 1, the structure in which the semiconductor chip and the pedestal are joined is formed in an elongated shape, and a sensing unit is formed on one end side thereof, and the outside is connected to the other end side. A pad or the like for electrical connection is arranged. For this reason, the inner wall surface of the assembly prevents the parts other than the sensing part from touching the pressure measurement medium when the structure is housed in the assembly in which the case of the semiconductor pressure sensor, the wiring board, etc. are integrated. There is a problem that a structure for taking out an electric signal to the outside is complicated, for example, a sealing material must be disposed between the two structures so as to avoid both ends of the structure. In addition, it is necessary to increase the distance between the sensing unit and the location where the electrical signal is taken out so that parts other than the sensing unit do not touch the pressure measurement medium, which increases the chip area.

  Here, the case where the structure in which the semiconductor chip and the pedestal are joined is accommodated in the assembly, but another structure using the structure in which the semiconductor chip is joined to the pedestal, such as a resin mold, is used. However, since the above-described problems of the complexity of the structure for taking out the electric signal to the outside and the increase in the chip area occur in the same manner, it is desired to be able to solve these problems.

  The present invention has been made in view of the above points, and it is an object of the present invention to provide a semiconductor pressure sensor having a structure capable of simplifying a structure for taking out an electric signal to the outside and preventing an increase in chip area and a method for manufacturing the same.

  In order to achieve the above object, in the semiconductor pressure sensor of the present invention, the strain gauge (12) of the first surface is formed with the front surface as the first surface and the back surface as the second surface, and the second surface is a partial surface. Are removed, the semiconductor chip (1) in which the pressure detection diaphragm (13) is formed on the first surface side, and the base (3) bonded to the first surface side in the semiconductor chip (1). ), And a pedestal (3) is formed with a through hole (31) penetrating the front and back of the pedestal (3), and the through hole A penetration electrode (33) disposed in (31) and electrically connected to the strain gauge (12) is provided, and electricity to the outside of the strain gauge (12) is provided through the penetration electrode (33). It is characterized by the fact that it is configured so that a general connection is made.

  According to such a semiconductor pressure sensor, the through electrode (33) penetrating the pedestal (3) disposed on the second surface (back surface) side of the semiconductor chip (1) is provided, and the through electrode (33) is provided. Electrical connection to the outside of the strain gauge (12) is performed. For this reason, since it is not necessary to make the semiconductor chip (1) and the base (3) have an elongated shape, it is possible to prevent an increase in the chip area of the semiconductor chip (1) for constituting the structure (A). Since the structure is simple, the structure for taking out an electric signal to the outside is not complicated.

  In such a semiconductor pressure sensor, the pedestal (3) can be formed of an insulating substrate such as glass.

  The pedestal (3) may be made of silicon. In this case, since both the material constituting the pedestal (3) and the semiconductor chip (1) can be made of silicon, the thermal stress from the pedestal (3) can be minimized and a sensor having good temperature characteristics can be obtained. . Further, when the pedestal (3) is made of silicon in this way, a signal processing circuit connected to the strain gauge (12) can be formed on the pedestal (3). In this way, the circuit chip for forming the signal processing circuit can be eliminated or reduced in size.

  Since the pedestal (3) is made of silicon, the surface of the pedestal (3) and the inner wall of the through hole (31) are covered with an insulating film (34, 35), and the through electrode is covered with the insulating film (34, 35). (33) and the pedestal (3) will be insulated.

Further, the base (3) is joined to the semiconductor chip (1) via the spacer layer (2) . Then, the reference pressure chamber constituting window (21) or recess (24) is formed at a position corresponding to the diaphragm (13) formed on the semiconductor chip (1) in the spacer layer (2), and the through-hole is formed. forming a contact hole (22) in corresponding locations (31), the through electrode (33) is to be electrically connected to each configured as strain gauges (12) through the contact hole (22).

  At this time, if the contact isolation part (23) from which the spacer layer (2) is removed is formed so as to surround the contact hole (22), the spacer layer (2) is heated to a high temperature, for example, when the spacer layer (2) is made of polysilicon. Then, even in the case where there is a possibility that the resistance value decreases and insulation is not sufficient, each contact hole (22) can be prevented from being electrically connected through the spacer layer (2).

  Moreover, the shape of the through-hole (31) formed in the base (3) is arbitrary, and can be formed in a taper shape or perpendicular to the surface of the base (3). Further, the through electrode (33) may be formed so as to fill the through hole (31) or may be formed on the surface of the through hole (31) with a constant film thickness.

  Although the semiconductor chip (1) may be formed from a single silicon substrate (10), the SOI is obtained by forming an SOI layer (18) on an insulating film (17) on a support substrate (16). You may be comprised by the board | substrate (19). In this case, the strain gauge (12) is insulated by, for example, a trench formed so as to reach the insulating film (17) through the SOI layer (18) and an insulator (19a) formed in the trench. Composed by separating.

  The structure (A) as described above includes, for example, a hollow portion in which the structure (A) is accommodated and an electrical connection between the strain gauge (12) provided in the structure (A) and the outside through the hollow portion. It is accommodated in an assembly (B) constituting a case (4, 6) provided with external connection wiring (41, 5, 61) for connection.

  In such a configuration, the pedestal (3) side of the structure (A) is directed to the inside of the hollow portion, so that the external connection wiring (41, 5, 61) is connected to the strain gauge (12 through the through electrode (33). ), And the pressure measurement medium is guided to the second surface side of the semiconductor chip (1).

  Therefore, the semiconductor chip (1) and the pedestal (3) do not need to be elongated along the hollow portion provided in the assembly (B), and the structure (A) is configured as described above. The increase of the chip area of the semiconductor chip (1) can be prevented.

  Further, in such a structure, as long as the through electrode (33) is electrically joined to the external connection wiring (41, 5, 61), it is between the inner wall surface of the hollow portion and the structure (A). It is only necessary to inject a protective material (43), and a sealing material must be arranged between the inner wall surface of the assembly (B) and the structure (A) so as to avoid both ends of the structure (A). The structure for extracting the signal to the outside is not complicated.

  Specifically, the external connection wiring (41, 5, 61) includes a lead pin (41) disposed in a hollow portion, and the through electrode (33) is joined to the lead pin (41). It can be configured.

  Further, the mounting substrate (8) including the wiring portion (8a) is provided, and the structure (A) is mounted on the mounting substrate (8) by extending the through electrode (33) to the surface and side surfaces of the base (3). On the other hand, a vertically mounted structure may be employed such that a portion of the through electrode (33) located on the side surface of the base (3) is connected to the wiring portion (8a).

  Furthermore, the lead frame (70) electrically connected to the through electrode (33) formed in the structure (A), the second surface side of the semiconductor chip (1), and the tip position of the lead frame (70) It can also be set as the structure provided with the mold resin (71) which seals a structure (A) and a lead frame (70) so that it may expose.

  In the above description, the case where the present invention is grasped as an apparatus invention called a semiconductor pressure sensor has been described. However, the present invention described below can be grasped as a manufacturing method invention.

  That is, in the present invention, a step of forming the strain gauge (12) on the surface layer portion of the semiconductor chip (1), a step of forming the spacer layer (2) on the first surface side of the semiconductor chip (1), and the spacer layer For (2), a pressure reference chamber forming window (21) or recess (24) is formed, and a contact hole (22) for electrical connection with the strain gauge (12) is formed. A step of bonding the pedestal (3) to the opposite side of the semiconductor chip (1) with the spacer layer (2) in between, and a partial etching of the pedestal (3) so that the front and back sides of the pedestal (3) Forming a through-hole (31) so as to penetrate through, forming a through-electrode (33) in the through-hole (31), and disposing a mask (14) on the second surface of the semiconductor chip (1) After that, the semiconductor chip (1) is etched from the second surface side. Thinning by, is characterized also include the steps of forming a diaphragm (13), the.

  By such a manufacturing process, the strain gauge (12) of the first surface is formed with the front surface as the first surface and the back surface as the second surface, and the second surface is partially removed, A semiconductor chip (1) having a pressure detection diaphragm (13) formed on one surface side, and a pedestal (3) bonded to the opposite side of the semiconductor chip (1) with the spacer layer (2) interposed therebetween; The pedestal (3) is formed with a through hole (31) penetrating the front and back of the pedestal (3) and disposed in the through hole (31), and the strain gauge (12 ), A semiconductor pressure sensor including a structure (A) provided with a through electrode (33) electrically connected to the substrate can be manufactured.

  In this case, in the step of forming the window portion (21) or the concave portion (24) and the contact hole (22) in the spacer layer (2), the spacer layer (2) is removed so as to surround the contact hole (22) and the contact is made. A step of forming the separation portion (23) can be performed.

  In the step of forming the spacer layer (2), the spacer layer (2) can be formed of polysilicon, but can also be formed of an oxide film. Thus, when forming the spacer layer (2) with an oxide film, in the step of bonding the pedestal (3), the pedestal (3) can be bonded to the spacer layer (2) by silicon direct bonding. Moreover, after performing the process of forming a recessed part (24) and a contact hole (22) in a spacer layer (2), the process of thermally oxidizing a semiconductor chip (1) and forming an oxide film is performed, and this thermal oxidation process After this, the base (3) can be directly silicon bonded to the spacer layer (2). In the case of performing the thermal oxidation in this way, after the step of forming the through hole (31) in the pedestal (3) is further performed, the oxide film formed by thermal oxidation through the through hole (31) is etched. By backing, the surface of the semiconductor chip (1) can be exposed again from the contact hole (2).

  In the step of forming the through hole (31) with respect to the pedestal (3), the through hole (31) is also formed at the position of the side surface of the pedestal (3) to form the through electrode (33). If the through electrode (33) is also extended to the side surface of the pedestal (3) in the step of performing, the portion of the through electrode (33) located on the side surface of the pedestal (3) is the wiring portion. The structure (A) can also be mounted vertically on the mounting substrate (8) so as to be connected to (8a).

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
A first embodiment of the present invention will be described. FIG. 1 is a cross-sectional view of the semiconductor pressure sensor according to the present embodiment, and FIG. 2 is a diagram schematically showing an enlarged cross section of the structure A constituting the sensing unit in FIG. FIG. 3 is a diagram showing a top layout of the structure shown in FIG. FIG. 2 substantially corresponds to a cross section taken along the line AA in FIG. FIG. 4 is a diagram showing a circuit configuration of the semiconductor pressure sensor. Hereinafter, the structure of the semiconductor pressure sensor will be described with reference to these drawings.

  As shown in FIG. 1, the semiconductor pressure sensor includes a structure A that constitutes a sensing unit and an assembly B in which a case, wiring, and the like of the semiconductor pressure sensor are integrated. The structure A is fixed in the assembly B, so that electrical continuity with the outside can be achieved, and the structure A can be attached to a pipe or the like through which a pressure measurement medium flows.

  As shown in FIG. 2, the structure A has a front surface and a back surface of the semiconductor chip 1 as a first surface and a second surface, respectively, and a base 3 is bonded to the first surface via a spacer layer 2. It is configured. An oxide film 11 is formed on the first surface of the semiconductor chip 1, and a strain gauge 12 doped with n-type or p-type impurities is formed under the oxide film 11 (surface layer portion of the first surface of the semiconductor chip 1). Is formed. Further, the semiconductor chip 1 is formed with a diaphragm 13 configured to be partially thinned by etching from the second surface side at a position corresponding to the strain gauge 12 and to be bent with the application of pressure.

  As shown in FIG. 3, the strain gauge 12 is an edge portion of the diaphragm 13, that is, a thinned portion that is a boundary portion between a surface parallel to the first surface and a tapered surface (a square portion in FIG. 3). ). The strain gauges 12 are arranged one by one on each side of the quadrangle formed by the edge portion of the diaphragm 13, and they are electrically connected through the diffusion layer 14 formed on the surface layer portion of the semiconductor chip 1 in the same manner as the strain gauge 12. By being connected, it is connected in a Wheatstone bridge shape as shown in FIG. 4, and a sensing unit is configured.

  Specifically, a spacer layer 2 made of polysilicon or the like is formed on the surface of the oxide film 11 in the semiconductor chip 1, and an insulating substrate such as glass is formed on the opposite side of the semiconductor chip 1 across the spacer layer 2. The pedestal 3 is joined.

  Although FIG. 3 does not show a cross-sectional structure, hatching is shown in the spacer layer 2 for easy understanding of the drawing. As shown in this figure, a window portion 21 serving as a pressure reference chamber is formed at a location corresponding to the diaphragm 13 in the spacer layer 2, and corresponds to the connection position of each of the plurality of strain gauges 12, that is, the diffusion layer 14. Contact holes 22 are formed at each location. Furthermore, the spacer layer 2 is removed so as to surround each contact hole 22, thereby forming a contact isolation portion 23.

  On the other hand, a through hole 31 is formed at a position corresponding to the contact hole 22 in the pedestal 3, and a through electrode 33 is formed so as to fill the through hole 31 and the contact hole 22. With such a structure, the through electrode 33 is electrically connected to each diffusion layer 14 to form a circuit structure as shown in FIG.

  The spacer layer 2 is basically made of polysilicon, which is a high-resistance material, so that insulation between the diffusion layers 14 can be achieved. However, when the material such as polysilicon becomes high temperature, Since the resistance value decreases, insulation may not be sufficient. For this reason, the contact isolation portion 23 is formed so as to surround the contact hole 22 so that each contact hole 22 is not electrically connected through the spacer layer 2. Depending on the case, the contact separation portion 23 may be omitted.

  The structure A configured as described above has a so-called face-down structure in which the first surface side of the semiconductor chip 1 is joined to the pedestal 3 via the spacer layer 2, and the assembly A is formed in the assembly B through the through electrode 33 formed on the pedestal 3. The electric signal of the strain gauge 12 can be extracted to the outside through the external connection wiring including various provided circuits.

  On the other hand, the assembly B is configured to include a sensor housing 4, a flexible lead 5, and a connector 6, as shown in FIG.

  The sensor housing 4 has a hollow shape, and accommodates a plurality of lead pins 41 made of a conductive metal and a structure A in the hollow portion. The hollow portion of the sensor housing 4 is hermetically sealed with an insulator 42 such as glass hermetic, so that the plurality of lead pins 41 do not come into contact with each other or with the inner wall of the hollow portion of the sensor housing 4. .

  The pedestal 3 side of the structure A is directed to one end side of the lead pin 41, and the through electrode 33 exposed from the pedestal 3 is electrically connected to the lead pin 41 via solder or the like. The intermediate portion (position in the middle of the thickness) between the electrical connection portion and the semiconductor chip 1 is covered with a protective material 43 and sealed so that the electrical joint portion does not come into contact with the measurement medium.

  Note that a male screw groove 44 is formed in the outer periphery of the sensor housing 4. The male screw groove 44 is screwed into a female screw hole of a pipe (not shown) through which a measurement medium flows, so that a semiconductor pressure sensor is formed. Fixing to piping is performed.

  In this embodiment, the flexible lead 5 has a U shape as shown in FIG. 1, and a part thereof is electrically connected to the other end of the lead pin 41. The flexible lead 5 is mounted with a circuit chip 51, a capacitor 52, and the like constituting a signal processing circuit for processing an electrical signal of the sensing unit. The flexible lead 5 is formed with a part of external connection wiring such as a power line, a GND line, and an electric signal output line output from the sensing unit (not shown). Electrical connection between the circuit chip 51 and the capacitor 52 and the pads provided on the back surface of the capacitor 52 via solder or the like enables electrical connection between the desired line and the circuit chip 51 or the capacitor 52. ing.

  The connector 6 includes a connector pin 61, an O-ring 62, and the like, and is used for electrical connection with the outside via the connector pin 61.

  In the semiconductor pressure sensor configured as described above, the respective sections are electrically connected so as to have a circuit configuration as shown in FIG. 4, and the strain gauges 12 arranged so as to configure a Wheatstone bridge are opposed to each other. The pressure can be detected by increasing or decreasing the two resistance values according to the applied pressure. Further, by arranging the strain gauges 12 so that the absolute values of applied stresses are equal to the diaphragm 13, the combined resistance of the entire bridge is designed not to depend on pressure but only on temperature. can do. As a result, as in the circuit configuration shown in FIG. 4, a semiconductor type capable of temperature measurement with the potential difference between the two intermediate potentials of the Wheatstone bridge as the pressure output and the voltage applied to the Wheatstone bridge as the temperature output. It can be a pressure sensor. In such a configuration, since the temperature can be measured with only four terminals necessary for pressure detection, the number of lead pins 41 can be minimized, which contributes to reduction in size and cost. Since such a circuit structure is known in the above-mentioned Patent Document 1, details thereof are omitted.

  For temperature measurement, the semiconductor chip 1 may be separately provided with a diffusion resistor other than the temperature detection element, a metal thin film resistor having a large TCR, a diode, and the like.

  Then, the manufacturing method of the semiconductor type pressure sensor comprised as mentioned above is demonstrated. 5 and 6 are cross-sectional views showing the manufacturing process of the semiconductor pressure sensor according to the present embodiment, which will be described with reference to these drawings.

  First, in the step shown in FIG. 5A, for example, an n-type silicon substrate 10 constituting the semiconductor chip 1 is prepared, and the surface of the silicon substrate 10 is thermally oxidized to form an oxide film 11 having a desired film thickness. To do.

  In the step shown in FIG. 5B, after a mask for ion implantation is arranged on the first surface of the silicon substrate 10, for example, boron, which is a p-type impurity, is ion-implanted into a predetermined position on the first surface. After that, the p-type strain gauge 12 is formed by activating the implanted impurities by heat treatment. Although the strain gauge 12 is formed here by ion implantation, it may be formed by thermal diffusion.

  In the steps shown in FIGS. 5C and 5D, after the spacer layer 2 made of polysilicon (polycrystalline silicon) or the like is formed, the pressure reference chamber is formed by etching away the desired position of the spacer layer 2. A window portion 21, a contact hole 22, and a contact separation portion 23 for forming are formed.

  In the step shown in FIG. 5E, the base 3 made of glass or the like is anodically bonded to the surface of the spacer layer 2. Thereby, the window part 21 remains as a space, and a pressure reference chamber is formed. As for the bonding at this time, other methods such as Au eutectic, low melting point glass, solder, etc. can be used as long as the pressure reference chamber can be kept airtight.

  In the step shown in FIG. 6A, the portion corresponding to the contact hole 22 in the pedestal 3 is etched to form the tapered through hole 31.

  In the step shown in FIG. 6B, in order to make electrical connection with the strain gauge 12, a metal such as Al or a metal such as Cu as a base of plating is sequentially formed, and subsequently plating is performed. The through hole 31 is filled with metal 32.

  In the step shown in FIG. 6C, a desired position of the metal 32 is removed by etching, and the through electrode 33 is formed.

  In the step shown in FIG. 6D, after the nitride film 15 is formed on the surface of the second surface of the silicon substrate 10, the nitride film 15 is removed by etching at a position corresponding to the planned diaphragm formation region.

  In the step shown in FIG. 6E, the diaphragm 13 is formed by digging the silicon substrate 10 by performing etching using the nitride film 15 as a mask. Thereafter, the silicon substrate 10 is diced together with the pedestal 3 to divide it into chips, and a structure A including a sensing unit in which the semiconductor chip 1 is joined to the pedestal 3 via the spacer layer 2 is configured.

  The structure A thus configured is placed in the hollow portion of the sensor housing 4 in the assembly B provided with the sensor housing 4, the flexible lead 5, and the connector 6, and the lead pin 41 and the through electrode 33 are interposed via solder or the like. Are electrically joined, and then the protective material 43 is injected to complete the semiconductor pressure sensor of this embodiment.

  According to the semiconductor pressure sensor of the present embodiment described above, the through electrode 33 that penetrates the pedestal 3 disposed on the second surface (back surface) side of the semiconductor chip 1 is provided, and the strain gauge 12 of the strain gauge 12 is provided through the through electrode 33. An external electrical connection is made. For this reason, since it is not necessary to make the semiconductor chip 1 and the pedestal 3 have an elongated shape, an increase in the chip area of the semiconductor chip 1 for constituting the structure A can be prevented, and the structure is simple. The structure for taking out the electric signal to the outside is not complicated.

  In particular, according to the semiconductor pressure sensor of the present embodiment, the through electrode 33 is provided so as to penetrate the base 3 disposed on the second surface (back surface) side of the semiconductor chip 1, and the through electrode 33 is electrically connected to the lead pin 41. By connecting to, the electrical signal of the sensing unit can be output to the outside. For this reason, since it is not necessary to make the semiconductor chip 1 and the pedestal 3 have an elongated shape along the hollow portion of the sensor housing 4 in the assembly B, as described above, the chip area of the semiconductor chip 1 for constituting the structure A Can be avoided.

  Further, in such a structure, as long as the through electrode 33 is electrically joined to the lead pin 41, the protective material 43 is simply injected between the inner wall surface of the hollow portion of the sensor housing 4 and the structure A. The structure for taking out an electrical signal to the outside does not become complicated, for example, a sealing material must be disposed between the inner wall surface of the assembly B and the structure A so as to avoid both ends of the structure A.

  Furthermore, in the case of the structure disclosed in Patent Document 1, the electrical connection with the outside is also performed by arranging the pads and the like between the semiconductor chip and the pedestal, and the length of the semiconductor chip in the longitudinal direction is longer than that of the pedestal. By doing so, the pad or the like is exposed from the pedestal, and the pad and the wiring of the wiring board installed on the assembly side are connected by a bonding wire. At this time, since the surface of the semiconductor chip on which the pad is formed and the surface of the wiring board installed on the assembly side are perpendicular to each other, the mounting process such as wire bonding becomes complicated.

  On the other hand, according to the semiconductor pressure sensor of this embodiment, since the through electrode 33 may be electrically joined to the lead pin 41, the surface of the semiconductor chip on which the pad is formed and the assembly side as in the prior art. The problem that the mounting process such as wire bonding becomes complicated because the surface of the wiring board placed on the board becomes vertical can be solved.

(Second Embodiment)
A second embodiment of the present invention will be described. This embodiment is different from the first embodiment in the structure of the structure A that constitutes the sensing unit in the semiconductor pressure sensor, and is otherwise the same as the first embodiment. Only the structure A different from the embodiment will be described.

  FIG. 7 is a cross-sectional view of the structure A constituting the sensing unit in the semiconductor pressure sensor of the present embodiment. As shown in this figure, in the semiconductor pressure sensor of this embodiment, the spacer layer 2 is formed of an oxide film, and the spacer layer 2 is partially etched to the extent that the surface of the semiconductor chip 1 is not exposed. A recess 24 is formed. A pedestal 3 made of silicon is connected to the surface of the spacer layer 2 by silicon direct bonding. A pressure reference chamber is formed between the spacer layer 2 and the pedestal 3 in the recess 24 formed in the spacer layer 2.

  With this structure, not only the same effects as in the first embodiment can be obtained, but also the material constituting the base 3 and the semiconductor chip 1 can be made of silicon, so that the thermal stress from the base 3 can be minimized. It is possible to provide a sensor with good temperature characteristics.

  As shown in this figure, since the bonded pedestal 3 is made of silicon, in order to ensure insulation with the electrode 33, the surface of the pedestal 3 and the inner walls of the through holes 31 are formed on the insulating films 34 and 35. The structure is covered with

  Then, the manufacturing method of the semiconductor type pressure sensor of this embodiment is demonstrated. 8 to 10 are cross-sectional views showing the manufacturing process of the semiconductor pressure sensor of the present embodiment, which will be described with reference to these drawings.

  First, in the steps shown in FIGS. 8A and 8B, the oxide film 11 is formed on the surface of the semiconductor chip 1 by performing the same steps as those in FIGS. 5A and 5B described above. A strain gauge 12 is formed on the surface layer portion of the semiconductor chip 1.

  In the steps shown in FIGS. 8C and 8D, after the oxide film is formed by the CVD method or the like, the spacer layer 2 is formed by performing a heat treatment to improve the film quality of the oxide film. Then, by removing the desired position of the spacer layer 2 by etching, the recess 24 and the contact hole 22 for forming the pressure reference chamber are formed. 8E, thermal oxidation is performed again to form an oxide film 7 for protecting the PN junction portion of the strain gauge 12.

  Next, in the step shown in FIG. 9A, the base 3 made of high-resistance silicon is joined to the surface of the spacer layer 2 by direct silicon joining, and the thickness of the base 3 is reduced by grinding the silicon if necessary. adjust. Thereby, the recess 24 formed in the spacer layer 2 remains as a space, and a pressure reference chamber is formed between the pedestal 3 and the spacer layer 2. Subsequently, in the process shown in FIG. 9B, the insulating film 34 is formed by CVD or thermal oxidation, and a region where the through hole 31 is to be formed is opened in the insulating film 34. By performing etching using the insulating film 34 as a mask, a through hole 31 is formed in a portion of the base 3 corresponding to the contact hole 22.

Subsequently, in the step shown in FIG. 9C, after an insulating film 35 made of SiO ₂ is formed on the inner wall (side surface) of the through hole 31 by thermal oxidation, the spacer layer 2 is retracted by etching back, and strain is applied. The gauge 12 is exposed. Then, in the step shown in FIG. 9D, the through hole 31 is filled with a metal 32 for electrical connection with the strain gauge 12. Thereafter, in a step shown in FIG. 9E, a desired position of the metal 32 is removed by etching, and the through electrode 33 is formed.

  Then, in the steps shown in FIGS. 10A and 10B, etching is performed using the nitride film 14 formed on the second surface of the silicon substrate 10 as a mask in the same steps as FIGS. 6D and 6E. As a result, the silicon substrate 10 is dug to form the diaphragm 13. Thereafter, the silicon substrate 10 is diced together with the pedestal 3 to divide it into chips, and a structure A including a sensing unit in which the semiconductor chip 1 is joined to the pedestal 3 via the spacer layer 2 is configured.

  The structure A thus configured is placed in the hollow portion of the sensor housing 4 in the assembly B provided with the sensor housing 4, the flexible lead 5, and the connector 6, and the lead pin 41 and the through electrode 33 are interposed via solder or the like. Are electrically joined, and then the protective material 43 is injected to complete the semiconductor pressure sensor of this embodiment.

(Third embodiment)
A third embodiment of the present invention will be described. The present embodiment is different from the first embodiment in the electrical connection structure of the structure A constituting the sensing unit in the semiconductor pressure sensor, and is otherwise the same as the first embodiment. Therefore, only the structure A different from the first embodiment will be described.

  FIG. 11 is a cross-sectional view of the structure A constituting the sensing unit in the semiconductor pressure sensor of the present embodiment. As shown in this figure, the structure A constituting the sensing unit shown in the first or second embodiment is vertically mounted. Specifically, the through electrode 33 extends from the surface of the pedestal 3 to the side surface, and the through electrode 33 is joined to the wiring portion 8 a provided on the mounting substrate 8 on the side surface of the pedestal 3. . In this way, the structure A can be mounted vertically, and even with such a structure, it is possible to simplify the structure for taking out an electric signal to the outside and prevent an increase in the chip area.

  In the case of such a structure, the electrical signal is taken out from the side surface of the structure A, and the surface side of the base 3 is restrained by another member or the like for taking out the electrical signal. Therefore, the influence of thermal stress from the sensor housing 4 or the like can be minimized, and a sensor with good temperature characteristics can be obtained.

  In the case of such vertical mounting, instead of the through electrode 33 being directly joined to the lead pin 41 as in the first and second embodiments, it is electrically connected to other wirings and the like via the mounting substrate 8. However, the mounting substrate 8 is inserted into the hollow portion of the sensor housing 4 together with the mounting substrate 8 so that the mounting substrate 8 protrudes from the hollow portion of the sensor housing 4 and the wiring portion 8 a and the wiring portion of the flexible lead 5. It may be in a form that can be electrically connected to.

(Other embodiments)
In the first and second embodiments, the structure, material, and the like of each part constituting the structure A and the assembly B are described by way of example. However, these are merely examples and various improvements are made. Is possible.

  For example, in the said 1st Embodiment, the taper-shaped through-hole 31 was formed with respect to the base 3, and what provided the through-electrode 33 so that this through-hole 31 might be filled up was shown. However, this is merely an example, and other structures may be used. 12 to 14 are cross-sectional views of the structure A when the shape of the through hole 31 or the shape of the through electrode 33 is changed.

  As shown in FIG. 12, the through hole 31 may be processed perpendicular to the pedestal 3. In addition, as shown in FIG. 13, the through hole 31 may be formed only on the surface of the through hole 31 without filling the through hole 31 with the through electrode 33. Further, as shown in FIG. 14, an SOI substrate 19 in which an SOI (Silicon on insulator) layer 18 is formed on the surface of the support substrate 16 via an insulating film 17 may be used instead of the silicon substrate 10. In this case, each strain gauge 12 is doped with impurities in the SOI layer 18, and then trench processing that reaches the insulating film 17 is performed on the SOI layer 18, and the inside of the trench is insulated and separated by the insulator 19 a. Composed. If the SOI substrate 19 is used in this way, a semiconductor pressure sensor can be used at a higher temperature. The same effect can be obtained even if the substrate is not the SOI substrate 19 but a substrate in which polycrystalline silicon is formed on the support substrate via an insulating film.

  Furthermore, although each said embodiment demonstrated the case where the structure A was accommodated in the assembly B, it is good also as a mounting form which resin-molds the structure A shown in each said embodiment. FIG. 15 shows a cross-sectional structure of a semiconductor pressure sensor in which the structure A is resin-molded. As shown in this figure, in the face-down structure in which the pedestal 3 is attached to the surface of the semiconductor chip 1 on the side where the sensing unit is configured, the through electrode 33 formed in the through hole 31 of the pedestal 3 is formed on the lead frame 70. The semiconductor chip 1 and the lead frame 70 are partially sealed with the mold resin 71 so that the second surface side (the recessed portion of the diaphragm 13) and the terminal portion of the lead frame 70 in the semiconductor chip 1 are exposed. A stopped structure may be used.

  Further, in the first and second embodiments, as shown in FIGS. 6 and 10, the case where the diaphragm 13 is formed after the through electrode 33 is formed has been described as an example. However, the diaphragm 13 is formed. After that, the through electrode 33 may be formed.

  Further, with respect to the vertical mounting structure shown in the third embodiment and the structures shown in FIGS. 12 to 15, the pedestal 3 as shown in the first embodiment is made of an insulating substrate such as glass. Of course, the present invention can be applied to the case where the pedestal 3 as shown in the second embodiment is made of silicon.

  In each of the above embodiments, when the pedestal 3 is made of silicon, a signal processing circuit or the like can be built in the pedestal 3. In this way, the circuit chip 51 for the signal processing circuit can be eliminated or downsized.

It is sectional drawing of the semiconductor type pressure sensor concerning 1st Embodiment of this invention. It is an expanded sectional view of the structure A which comprises the sensing part in FIG. It is the figure which showed the upper surface layout of the structure A shown in FIG. It is the figure which showed the circuit structure of the semiconductor type pressure sensor shown in FIG. It is sectional drawing which showed the manufacturing process of the structure A of the semiconductor type pressure sensor shown in FIG. It is sectional drawing which showed the manufacturing process of the structure A of the semiconductor type pressure sensor following FIG. It is sectional drawing of the structure A which comprises the sensing part concerning the semiconductor type pressure sensor of 2nd Embodiment of this invention. It is sectional drawing which showed the manufacturing process of the structure A of the semiconductor type pressure sensor shown in FIG. FIG. 9 is a cross-sectional view illustrating the manufacturing process of the structure A of the semiconductor pressure sensor subsequent to FIG. 8. FIG. 10 is a cross-sectional view showing a manufacturing process of the structure A of the semiconductor pressure sensor subsequent to FIG. 9. It is sectional drawing of the structure A which comprises the sensing part concerning the semiconductor type pressure sensor of 3rd Embodiment of this invention. It is sectional drawing of the structure A which comprises the sensing part concerning the semiconductor type pressure sensor of other embodiment of this invention. It is sectional drawing of the structure A which comprises the sensing part concerning the semiconductor type pressure sensor of other embodiment of this invention. It is sectional drawing of the structure A which comprises the sensing part concerning the semiconductor type pressure sensor of other embodiment of this invention. It is the figure which showed the cross-sectional structure of the semiconductor-type pressure sensor which resin-molded the structure A.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Semiconductor chip, 2 ... Spacer layer, 3 ... Base, 4 ... Sensor housing, 5 ... Flexible lead, 6 ... Connector, 7 ... Oxide film, 8 ... Mounting substrate, 8a ... Wiring part, 10 ... Silicon substrate, 11 ... Oxide film, 12 ... strain gauge, 13 ... diaphragm, 14 ... diffusion layer, 15 ... nitride film, 16 ... support substrate, 17 ... insulating film, 18 ... SOI layer, 19 ... SOI substrate, 19a ... insulator, 21 ... window , 22 ... contact hole, 23 ... contact separation part, 23 ... recess, 24 ... recess, 31 ... through hole, 32 ... metal, 33 ... through electrode, 34, 35 ... insulating film, 41 ... lead pin, 42 ... insulator 43 ... Protective material, 44 ... Male thread groove, 51 ... Circuit chip, 52 ... Capacitor, 61 ... Connector pin, 62 ... O-ring, 70 ... Lead frame, 71 ... Mold resin, A ... Structure, B ... Assemblies Yellowtail.

Claims (20)

The strain gauge (12) of the first surface is formed with the front surface as the first surface and the back surface as the second surface, and the second surface is partially removed, so that the first surface side A structure having a semiconductor chip (1) formed with a pressure detection diaphragm (13) and a base (3) bonded to the first surface side of the semiconductor chip (1). (A)
The pedestal (3) is formed with a through hole (31) penetrating the front and back of the pedestal (3), and is disposed in the through hole (31), and is attached to the strain gauge (12). An electrically connected through electrode (33) is provided, and is configured to be electrically connected to the outside of the strain gauge (12) through the through electrode (33) .
The pedestal (3) is joined to the semiconductor chip (1) via a spacer layer (2), and the diaphragm (13) formed on the semiconductor chip (1) of the spacer layer (2). A window (21) or a recess (24) for forming a reference pressure chamber is formed at a position corresponding to the contact hole (22), and a contact hole (22) is formed at a position corresponding to the through hole (31). A semiconductor pressure sensor, wherein the through electrode (33) is electrically connected to the strain gauge (12) through a hole (22) .   The semiconductor pressure sensor according to claim 1, wherein the pedestal (3) is formed of an insulating substrate.   The semiconductor pressure sensor according to claim 1, wherein the base (3) is made of silicon.   The semiconductor pressure sensor according to claim 3, wherein a signal processing circuit connected to the strain gauge (12) is formed on the pedestal (3).   The surface of the pedestal (3) and the inner wall of the through hole (31) are covered with an insulating film (34, 35), and the through electrode (33) and the pedestal (3) are covered by the insulating film (34, 35). The semiconductor pressure sensor according to claim 3 or 4, wherein the pressure sensor is insulated. Semiconductor type according to any one of claims 1 to 5, characterized in that said spacer layer so as to surround the contact hole (22) (2) contact separation section to remove (23) is formed Pressure sensor. Wherein formed in the base (3) through holes (31), with claim 1, characterized in that it is tapered or vertically formed to the surface of the pedestal (3) 6 1 Semiconductor pressure sensor as described in 1. The semiconductor pressure sensor according to any one of claims 1 to 7 , wherein the through electrode (33) is formed to fill up the through hole (31). The semiconductor pressure sensor according to any one of claims 1 to 7 , wherein the through electrode (33) is formed on the surface of the through hole (31) with a constant film thickness. The semiconductor chip (1) is composed of an SOI substrate (19) in which an SOI layer (18) is formed on a support substrate (16) via an insulating film (17), and the strain gauge (12) It is constituted by insulating and separating by a trench formed so as to penetrate the SOI layer (18) and reach the insulating film (17) and an insulator (19a) formed in the trench. the semiconductor pressure sensor as claimed in any one of claims 1, wherein 9. In order to provide an electrical connection between the strain gauge (12) provided in the structure (A) and the outside through the hollow portion, the hollow portion in which the structure (A) is accommodated. Having an assembly (B) constituting a case (4, 5) provided with the external connection wiring (41, 5, 61) of
The external connection wiring (41, 5, 61) is connected to the strain gauge (12) via the through electrode (33) by the pedestal (3) side of the structure (A) being directed to the inside of the hollow portion. and are electrically connected, according to any one of claims 1 to 10, characterized in that is configured to measure medium pressure is led to the second surface side of said semiconductor chip (1) Semiconductor pressure sensor. The external connection wiring (41, 5, 61) includes a lead pin (41) disposed in the hollow portion, and the through electrode (33) is joined to the lead pin (41). The semiconductor type pressure sensor according to claim 11 . A mounting substrate (8) having a wiring portion (8a) formed thereon;
The through electrode (33) extends to the surface and side surface of the pedestal (3),
The structure (A) is vertically oriented with respect to the mounting substrate (8) so that a portion of the through electrode (33) located on the side surface of the base (3) is connected to the wiring portion (8a). the semiconductor pressure sensor as claimed in any one of claims 1 to 10, characterized in that it is placed implemented. A lead frame (70) electrically connected to the through electrode (33) formed in the structure (A);
Mold resin (71) for sealing the structure (A) and the lead frame (70) so as to expose the second surface side of the semiconductor chip (1) and the tip position of the lead frame (70). the semiconductor pressure sensor as claimed in any one of claims 1 to 10, characterized in that it comprises, when. The strain gauge (12) of the first surface is formed with the front surface as the first surface and the back surface as the second surface, and the second surface is partially removed, so that the first surface side A structure having a semiconductor chip (1) formed with a pressure detection diaphragm (13) and a base (3) bonded to the first surface side of the semiconductor chip (1). (A)
The pedestal (3) is formed with a through hole (31) penetrating the front and back of the pedestal (3), and is disposed in the through hole (31), and is attached to the strain gauge (12). A semiconductor-type pressure which is provided with an electrically connected through electrode (33) and is configured to be electrically connected to the outside of the strain gauge (12) through the through electrode (33). A method for manufacturing a sensor, comprising:
Forming the strain gauge (12) on the surface layer of the semiconductor chip (1);
Forming a spacer layer (2) on the first surface side of the semiconductor chip (1);
In the spacer layer (2), a pressure reference chamber forming window (21) or recess (24) is formed, and a contact hole (for making electrical connection with the strain gauge (12)) ( 22) forming,
Bonding the pedestal (3) to the opposite side of the semiconductor chip (1) across the spacer layer (2);
Forming the through hole (31) so as to penetrate the front and back of the pedestal (3) by partially etching the pedestal (3);
Forming the through electrode (33) in the through hole (31);
A step of disposing the mask (14) on the second surface of the semiconductor chip (1) and then forming the diaphragm (13) by thinning the semiconductor chip (1) by etching from the second surface side. And a method for manufacturing a semiconductor pressure sensor. In the step of forming the window (21) or the recess (24) and the contact hole (22) in the spacer layer (2), the spacer layer (2) is removed so as to surround the contact hole (22). The method of manufacturing a semiconductor pressure sensor according to claim 15 , further comprising a step of forming a contact separation portion (23). The method of manufacturing a semiconductor pressure sensor according to claim 15 or 16 , wherein in the step of forming the spacer layer (2), the spacer layer (2) is formed of polysilicon. In the step of forming the spacer layer (2), the spacer layer (2) is formed of an oxide film,
The step of bonding the pedestal (3) is characterized in that the pedestal (3) is made of silicon, and the pedestal (3) is bonded to the spacer layer (2) by direct silicon bonding. A method for manufacturing a semiconductor pressure sensor according to 15 or 16 . After performing the step of forming the recess (24) and the contact hole (22) in the spacer layer (2), the step of thermally oxidizing the semiconductor chip (1) to form an oxide film, After the oxidation step, the pedestal (3) is directly silicon bonded to the spacer layer (2),
Further, after performing the step of forming the through hole (31) in the pedestal (3), the oxide film formed by the thermal oxidation is etched back through the through hole (31), so that the contact hole ( The method of manufacturing a semiconductor pressure sensor according to claim 18 , wherein the step of reexposing the surface of the semiconductor chip (1) from 2) is performed. In the step of forming the through hole (31) with respect to the pedestal (3), the through hole (31) is also formed at the position of the side surface of the pedestal (3),
In the step of forming the through electrode (33), the through electrode (33) is also extended to the side surface of the base (3),
A mounting substrate (8) on which a wiring portion (8a) is formed is prepared, and a portion of the through electrode (33) located on the side surface of the base (3) is connected to the wiring portion (8a). , semiconductor pressure according the structure of (a) to any one of claims 15 to 19, characterized in that includes the steps of mounting a tower orientation with respect to said mounting substrate (8) Sensor manufacturing method.

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