WO2003063258A1

WO2003063258A1 - Semiconductor device

Info

Publication number: WO2003063258A1
Application number: PCT/JP2002/000510
Authority: WO
Inventors: Naoki Yutani; Tsukasa Matsuura; Kazuhiko Tsutsumi
Original assignee: Mitsubishi Denki Kabushiki Kaisha
Priority date: 2002-01-24
Filing date: 2002-01-24
Publication date: 2003-07-31
Also published as: JPWO2003063258A1

Abstract

A semiconductor device keeps the base material of a semiconductor substrate (2) partially removed from the rear in a partial region of a wiring to a semiconductor element (2) arranged on the surface of a semiconductor substrate (1) to from a diaphragm section (4) comprising the upper and lower insulating films of a front wiring (3). A part of the insulating film on the rear of the diaphragm has a contact hole (10) to the front wiring, and a rear wiring (6) formed on the rear of the substrate via the insulating film is electrically connected to the front wiring through the contact hole. The rear wiring is electrically connected to a rear input/output pad (12), and an insulating resin (19) is embedded in the rear opening of the diaphragm section.

Description

Technical field

The present invention relates to a structure of a semiconductor device in which inputs and outputs of elements formed on a front surface of a substrate can be extracted from a back surface of the substrate.

Light

Fine

Landscape technology

FIG. 9 is an external view of an element schematically showing a part of a flow rate detecting element which is one of the thermal sensors disclosed in, for example, Japanese Patent Application Laid-Open No. Hei 11-12845. FIG. 1 is a cross-sectional view including the mounting form of the thermal sensor of FIG.

In the figure, reference numeral 101 denotes a flat substrate constituting a thermal sensor element 100 cut out of, for example, a silicon wafer, and 107 and 108 are formed on one surface of the flat substrate 1. An insulating support film, for example, a silicon nitride film. The silicon nitride film 108 also serves as a protective film. A thermal resistor film 102 is formed between the silicon nitride films 107 and 108. The heat-sensitive resistor film 102 corresponds to a heat-generating portion used for a heat-generating resistor and a temperature-measuring resistor, and is made of, for example, platinum. Also, the silicon substrate 101 around the heat-sensitive resistor film 102 is removed so that the heat generated in the heat-sensitive resistor film 102 does not escape to the silicon substrate 101 and the temperature of the heat-generating portion rises. (101a) A diaphragm 105 composed of silicon nitride films 107 and 108 is formed. Reference numeral 103 denotes a wiring connecting the thermal resistance film 102 and the input / output pad 150, and is formed of the same film as the thermal resistance film 102, for example. Reference numeral 151 denotes a thermal sensor package, for example, epoxy resin. The substrate 101 of the thermal sensor element 100 0 0 is fixed to the package 15 1 with an adhesive 15 5 c 15 3 is the external input / output lead, 15 4 is the input / output pad 15 0 External input / output A wire-bonding material for electrically connecting the leads 153 is, for example, a gold (Au) wire having a diameter of 25 μm. Reference numeral 152 denotes a cover of the package 151, which covers the wire bond 154.

Next, a method of manufacturing the main part of the thermal sensor element shown in FIGS. 9 and 10 will be described. For example, a silicon nitride film 107 having a thickness of about 410 is formed on a plate-shaped base material silicon wafer having a thickness of about 400 / m by a method such as a sputter method, and further thereon. For example, a heat-sensitive resistor film 102 made of platinum or the like having a thickness of 0.2 m is formed by an evaporation method, a sputtering method, or the like. After that, anneal for several hours at about 600 ° C for stabilization. The platinum film 102 is subjected to patterning using a photoengraving method, an etching method, a dry etching method, or the like, whereby the heat generating portion 102 of the pattern as shown in FIG. And the wiring 103 are formed. On the patterned platinum films 102 and 103, a silicon nitride film 108 having a thickness of about 0.8 μm is formed as a protective film by a sputtering method or the like. Next, a part of the back surface protective film 108 on the wiring 103 is etched using a photolithography method or the like to form an input / output unit 150. The diaphragm 105 composed of the silicon nitride films 107 and 108 is formed on the surface opposite to the surface on which the support films 107 and 108 are disposed by using a photolithography method or the like. It is formed by performing a desired patterning, for example, by applying an Al force retching. The thermal sensor element created in this way is fixed to the package 15 1 with adhesive 15 5, and the thermal sensor element input / output pad 150 and external input / output lead 15 3 are connected with the wire bond 15 4 ^ Continue. Finally, the lid 15 2 of the package is bonded and fixed to protect the wire bond portion. In this way, a thermal sensor on which the elements are mounted is completed.

Next, the operation when the thermal sensor element is used as a flow sensor will be described. An electric current is applied to the heat-sensitive resistive film 102 to generate heat. As shown by the arrow Y in Fig. 9, the element is positioned so that the gas for which With this arrangement, the greater the gas flow rate, the greater the amount of heat taken from the surface of the heating part. Therefore, when a constant current is applied to the heat-sensitive resistive film, the temperature of the heat-generating part decreases as the flow rate increases. For example, when a platinum resistance film is used for the heating section, the resistance value decreases as the temperature of the resistance film decreases, so that the flow rate can be obtained as a change in the resistance value. Heat generation and temperature measurement may be composed of separate resistors. There is also a reading method in which the current value is increased by an amount corresponding to an increase in the amount of heat taken away due to an increase in the flow rate so that the temperature of the heating portion is constantly kept constant, and a change in the control current is used as a signal output. . Further, since the output varies depending on the outside air temperature, an outside air temperature sensor for temperature correction may be formed on the substrate 101 in some cases. The package 151 is designed in a wing shape so that there is no turbulence in the air flow near the detector 102 of the thermal sensor, and is designed to have no irregularities around the detector. Therefore, the distance X (shown in Fig. 10) from the detector to the package lid 152 needs to be large enough not to disturb the air flow, and it is preferable that it is about 2mm or more.

As described above, in the conventional thermal sensor, since the signal output unit 150 is formed on the same surface as the detection unit 102 of the substrate 101 constituting the sensor element, The output section had to be sufficiently separated from the detection section so as not to affect it, and it was necessary to make the wiring area from the detection section to the output section long. As a result, there have been problems in that the element size is increased, the manufacturing cost of the element is increased, and the packaging structure is complicated and large in mounting, which increases the number of assembly steps and component costs.

The present invention has been made to solve the above problems, and has as its object to obtain a semiconductor device having a small and simple mounting structure. That is, in a semiconductor device having a semiconductor element section (in the above example, a thermal sensor having a thermosensitive resistor film in the semiconductor element section), the mounting structure for input / output wiring to the semiconductor element section is simplified and reduced in size. is there. Disclosure of the invention

A semiconductor device according to the present invention includes a semiconductor element on a first surface of a semiconductor substrate, a first input / output wiring to the semiconductor element, and a portion including at least a partial region of the first input / output wiring. The semiconductor substrate is removed to form a diaphragm structure, and the first input / output wiring and the input / output portion formed on the second surface of the semiconductor substrate are connected to the second input / output via the diaphragm structure. The structure was such that an insulating resin was provided in a removed portion of the semiconductor substrate on which the diaphragm structure was formed, by connecting with wiring. In other words, the input / output wiring of the element formed on the surface of the substrate is connected to the wiring on the back surface of the substrate at the contact portion of the diaphragm structure that can be easily created. The input / output section, which had to be performed, can now be formed on the back surface of the substrate, and the size of the element can be reduced, and the manufacturing cost can be reduced. In addition, because the output can be taken out from the surface opposite to the detection surface, the choice of mounting structure is expanded, and it is possible to select the optimal mounting form according to the usage condition of the element, simplifying the mounting structure and assembling This has the effect of reducing man-hours and the number of mounted components, thus reducing costs. In addition, since the diaphragm is filled with resin, the backside wiring is protected from the outside air, and the strength of the diaphragm and the connection is improved. In addition, the filler can reduce the thermal resistance of the diaphragm, suppress the heat generation of the contact when current is applied, and improve the electrical reliability of the contact.

In the above semiconductor device, the second input / output wiring and the input / output portion are covered with an insulating resin, so that if an insulating material having a passivation effect is used, entry of moisture from the outside air can be prevented. This has the effect of improving the reliability of the contact portion with the backside wiring and the topside wiring. In addition, it becomes possible to omit the protective film on the back surface. At this time, the insulating resin placed in the diaphragm and the second filler The insulating resin covering the output wiring and the input / output portion may be the same material.

Further, in the above semiconductor device, since a heat-sensitive resistor film is provided in the semiconductor element portion and a region including the heat-sensitive resistor film has a second diaphragm structure, a thermal sensor can be easily configured, and the conventional method for detecting the surface of a substrate The input / output unit, which had to be formed sufficiently separated from the unit, can be formed on the back surface of the substrate, so that the size of the element can be reduced and the manufacturing cost can be reduced. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic diagram for explaining a thermal sensor as a semiconductor device according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view showing a mounting form. FIG. 3 is a cross-sectional view for explaining a thermal sensor according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view for explaining a thermal sensor according to a third embodiment of the present invention.

FIG. 5 is a cross-sectional view for explaining a thermal sensor according to a fourth embodiment of the present invention.

FIG. 6 is a sectional view for explaining a thermal sensor according to a fifth embodiment of the present invention.

FIG. 7 is a sectional view for explaining a thermal sensor according to a sixth embodiment of the present invention.

FIG. 8 is a cross-sectional view for explaining a semiconductor device according to another embodiment of the present invention.

FIG. 9 is an external view of a sensor element showing the appearance of a conventional thermal sensor, and FIG. 10 is a schematic sectional view of the thermal sensor shown in FIG. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Example 1

FIG. 1 is a diagram for explaining an example in which a semiconductor device according to an embodiment of the present invention is applied to a thermal flow sensor, and is an external view of an element of the flow sensor. FIG. 2 is a cross-sectional view showing a mounting form of the flow sensor shown in FIG. In the figure, 1 is a flat substrate of a thermal sensor element cut out of, for example, a silicon wafer, and 7 and 8 are insulating support films formed on one surface of the flat substrate 1, for example, a silicon nitride film. Consists of The silicon nitride film 8 also serves as a protective film. The thermal resistor film 2 is formed between the silicon nitride films 7 and 8. The heat-sensitive resistor film 2 corresponds to a heat-generating portion used for a heat-generating resistor and a temperature-measuring resistor, and is made of, for example, platinum (Pt). Also, the silicon substrate 1 around the thermal resistor film 2 has been removed (1a) so that the heat generated in the thermal resistor film 2 does not escape to the silicon substrate 1 and the temperature of the heat generating portion rises. A diaphragm 5 composed of the dangling silicon films 7 and 8 is formed. Reference numeral 3 denotes a wiring on the front side electrically connected to the thermal resistor film 2 and is formed of, for example, the same film as the thermal resistor film 2. The silicon substrate 1 is removed in a part of the front side wiring 3 (lb), and a diaphragm 4 composed of silicon nitride films 7 and 8 is formed. Reference numeral 6 denotes a backside wiring, and 9 denotes an insulating layer for electrically insulating the backside wiring 6 from the substrate 1, for example, a silicon nitride film. Reference numeral 10 denotes a contact hole formed in the insulating layers 7 and 9 for electrically connecting the rear wiring 6 and the front wiring 3. Reference numeral 11 denotes a backside protective film, for example, a silicon nitride film. Reference numeral 12 denotes an opening of the backside protective film 11, which is an input / output pad of a thermal sensor. 21 is a package of a thermal sensor, for example, epoxy resin. The thermal sensor element 1 is fixed to the package 21 with an adhesive 18. Reference numeral 23 denotes an external input / output lead, reference numeral 24 denotes a wire bonding material for electrically connecting the input / output pad 12 and the external input / output lead 23, for example, a gold (Au) wire having a diameter of 25 mm. . Also, 2 2 is a package covering wire bond 24 2 1 is the lid. The thermal sensor element 1 is fixed to the package 21 with an adhesive 18. Reference numeral 19 denotes an insulating resin filled in the opening of the diaphragm 4, for example, a silicon resin or a polyimide resin.

Next, a method of manufacturing a main part of the thermal sensor element shown in FIGS. 1 and 2 will be described. On a silicon wafer 1 having a thickness of about 400 an, which is a plate-like base material, a silicon nitride film 7 having a thickness of, for example, about 1 μm is formed by a method such as a sputter method, and further, a thickness of, for example, A thermal resistor film 2 made of platinum or the like is formed by an evaporation method, a sputtering method, or the like. After that, anneal for several hours at about 600 ° C for stabilization. The platinum film 2 is patterned by photolithography, wet etching, dry etching, or the like, thereby forming a heating portion 2 and a surface wiring 3 having a pattern as shown in FIG. Is done. On the patterned platinum films 2 and 3, a silicon nitride film 8 having a thickness of about 0.8 μm is formed as a protective film by a sputtering method or the like. The diaphragm 5 composed of the silicon nitride films 7 and 8 performs a desired patterning by using a photoengraving method or the like on a surface opposite to the surface on which the support films 7 and 8 are disposed. It is formed by performing re-etching or the like. At this time, the diaphragm 4 may be formed at the same time. Next, a silicon nitride film 9 having a thickness of about 0.5 / m is formed on the back surface by a sputtering method or the like. A desired patterning is performed from the back side by using photolithography or the like, and the insulating films 9 and 10 are etched to form contact holes 10. In the contact hole 10, the surface wiring 3 is exposed. Thereafter, for example, an AlSi film is formed as a wiring film on the back surface by a sputtering method or the like. The back wiring film is subjected to desired patterning using photolithography or the like and etched to form the back wiring 6. Thus, the front surface wiring 3 and the rear surface wiring 6 are electrically connected by the contact hole 10. Next, a silicon nitride film having a thickness of about 0.8 / m is formed as a back surface protective film 11 by a sputtering method or the like. Next, a part of the backside protection crotch 11 on the backside wiring 6 is etched using photolithography and output. Form part 12 Finally, the opening of the diaphragm 4 is filled with an insulating material 19 of silicone resin. The thermal sensor element thus created is fixed to the package 21 with an adhesive 18, and the thermal sensor element input / output pad 12 and the external input / output lead 23 are connected with a wire-to-bond 24. The adhesive 18 may be of the same type as the insulating material 19. Finally, the package lid 22 is bonded and fixed to protect the wire bond. Example 2.

FIG. 3 is a view showing a cross section of a thermal sensor according to another embodiment of the present invention. The same numbers as in FIGS. 1 and 2 indicate the same or corresponding parts. In this embodiment, the backside protective film 11 in FIG. 2 is omitted, and the backside wiring 6 is directly filled with an insulating resin 19. The insulating resin 19 is, for example, a silicon resin or a polyimide resin. Reference numeral 31 denotes an insulating material applied so as to cover an exposed portion of the back wiring 6, which is, for example, a silicon resin or polyimide resin. These insulating materials 19 and 31 are made of a resin having a passivation effect for preventing intrusion of moisture or the like from the outside. The back wiring 6 is completely covered with the insulating material 31 and the buried insulating material 19. The insulating material 31 may be of the same type as the insulating material 19. Further, it may be the same type as the adhesive 18. Example 3.

FIG. 4 is a view showing a cross section of a thermal sensor according to another embodiment of the present invention, and shows an example in which the insulating material 31 in FIG. 3 is the same material as the embedded insulating material 19 and is formed at the same time. In this embodiment, the thermal sensor element is fixed to the package 21 with an adhesive 18 and the thermal sensor element input / output pad 12 and the external input / output lead 23 are connected by a wire-to-bond 24. Fill the opening with silicone resin 19. At this time, an insulating material 19 including a wire-to-bond portion is applied so that the back wiring 6 is completely covered. Finally in the package The cover 22 is bonded and fixed to protect the wire-to-bond portion.

Although the embodiments shown in FIGS. 3 and 4 show the structure in which the back surface protective film 11 shown in FIG. 2 is omitted, these may have a structure in which the back surface protective film 11 is provided. In this case, the insulating materials 19, 31 and the protective film 11 can prevent the intrusion of water or the like from the outside twice, and the reliability can be further improved. Example 4.

FIG. 5 is a view showing a cross section of a thermal sensor according to another embodiment of the present invention. The same numbers as in FIGS. 1 and 2 indicate the same or corresponding parts. 15 is a bump made of gold or solder. Reference numeral 32 denotes an insulating sealing material filled around the bump 15. This sealing material 32 may be of the same type as the adhesive material 18. Further, it may be the same type as the insulating material 19.

The mounting method of this embodiment will be described below. First, a gold bump having a height of, for example, 10 μm is formed on at least one of the input / output pad 12 and the output lead 23 of the thermal sensor element. Gold bumps are formed by pressing and fixing gold on individual pads using a wire-bonder, or by plating. Align the pad 12 of the thermal sensor element so that it is directly above the pad of the output lead 23, and then pressurize to raise the temperature and electrically connect the pads with a gold bump. At this time, ultrasonic waves may be applied to make the joint stronger. When a molten metal such as solder is used as the bump 15, it is prepared as follows. For example, solder bumps of about several tens of m / m are formed on both or any of the input / output pads 12 and the output leads 23 of the thermal sensor element by plating. The thermal sensor element is aligned so that the pad 12 is directly above the pad 14 of the wiring board 13 and then heated to a temperature at which the solder melts, and the pads are electrically connected by solder bumps. Finally, a sealing material 32 such as an epoxy resin and an adhesive 18 are put between the element and the package 21 and cured. In addition, a sealing material 32 that has a passivation effect is used. By completely covering the back wiring 6 with the buried insulating material 19, the insulating protective film 11 on the back can be omitted as in the embodiment of FIG. 4, and the number of manufacturing steps can be reduced. Embodiment 5.

FIG. 6 is a view showing a cross section of a thermal sensor according to another embodiment of the present invention. The same numbers as those in FIG. 5 indicate the same or corresponding parts. In the figure, reference numeral 13 denotes a wiring board for connecting the thermal sensor element and the signal processing circuit element 17 and is formed of, for example, glass epoxy resin. Reference numeral 14 denotes a wiring layer of the wiring board 13 which is electrically connected to the input / output pads 12 of the thermal sensor via bumps 15 and also used as bumps 16 for input / output pads of the signal processing circuit element 17. It is connected. The bumps 15 and 16 are formed of a molten metal such as gold or solder. The mounting method of this embodiment is described below. For example, a gold bump having a height of several tens / zm is formed on at least one of the input / output pad 12 of the thermal sensor element and the pad 14 of the wiring board 13. Gold bumps are formed by pressing and fixing gold on individual pads using a wire bonder, or by plating. The thermal sensor element is aligned so that the pad 12 is directly above the pad 14 of the wiring board 13 and then pressurized to increase the temperature, and the pads are electrically connected with gold bumps. At this time, ultrasonic waves may be applied to make the bonding stronger. When a molten metal such as solder is used as the bump 15, it is prepared as follows. For example, a solder bump of about several tens of meters or slightly more is formed on both or one of the input / output pad 12 of the thermal sensor element and the pad 14 of the wiring board 13. The thermal sensor element is aligned so that the pad 12 is directly above the pad 14 of the wiring board 13 and then heated to a temperature at which the solder melts, and the pads are electrically connected by solder bumps. Elements (not shown) such as elements 17 and resistors of the signal processing circuit are connected to the wiring board in the same manner. Next, contact with sealing material 32 such as epoxy resin. The adhesive 18 is put between the element and the circuit board and cured. The sealing material 32 and the adhesive 18 may be the same material. If the back wiring 6 is completely covered with the sealing material 3 2 having a passivation effect and the buried insulating material 19, the insulating protection film 11 on the back surface can be omitted as in the embodiment of FIG. And the number of production steps can be reduced. Finally, the entire surface except the detection surface is sealed with mold resin 25. This structure enables downsizing including the signal processing circuit. Embodiment 6.

FIG. 7 is a view showing a cross section of a thermal sensor according to another embodiment of the present invention. The same numbers as those in FIG. 6 indicate the same or corresponding parts. In the figure, 26 is a circuit portion of the signal processing circuit element 17, and 27 is a surface wiring. Reference numeral 28 denotes a rear surface wiring of the signal processing circuit element 17, and reference numeral 29 denotes a diaphragm opening for connecting the front surface wiring 27 and the rear surface wiring 28, which is insulated in the same manner as the opening of the diaphragm 4 of the sensor element. Resin 19 is filled. These are created in the same way as the sensor elements. In this embodiment, the back wiring 6 of the sensor element and the front wiring 27 of the signal processing circuit element 17 are electrically connected by the bump 15. As a result, the input and output of the sensor element are connected to the circuit section 26 by the surface wiring 27 and driven and signal processed. The surface wiring of the output of the circuit part 25 is connected to the back wiring 28 at the diaphragm opening 29, connected to the circuit board 13 by the bump 16, and connected to the outside by the lead 23. The method of connecting the bumps is the same as that of the fifth embodiment.In this embodiment, the bumps 16 are used to connect the circuit board and the back wiring of the signal processing circuit 17, and then the back wiring of the sensor element and the front wiring of the signal processing circuit are connected. The bumps 15 may be used for connection, or the front wiring of the signal processing circuit 17 and the back wiring of the sensor element 1 may be connected by the bump 15 and then the back wiring of the signal processing circuit 17 and the circuit board 13 may be bumped. You may connect with 16. Finally, the entire surface except for the detection surface is sealed with mold resin 25. This structure enables downsizing including the signal processing circuit. Although a thermal type flow sensor having a semiconductor element portion provided with a thermosensitive resistor film as a backside output semiconductor device has been described as an example, this may be another sensor. Further, a general semiconductor element such as a memory or a logic may be used. FIG. 8 shows a partial cross-sectional view of a semiconductor device in the case where the memory element 50 and the logic element 60 are connected in the same structure as in FIG. In the figure, 51 is a circuit portion of the memory element 50, and 52 is a surface wiring. Reference numeral 53 denotes a rear surface wiring of the memory element 50, 54 denotes a diaphragm opening for connecting the front surface wiring 52 and the rear surface wiring 53, and the opening of the diaphragm 4 of the sensor element shown in the above embodiment. Similarly, the insulating resin 19 is filled. Reference numeral 61 denotes a circuit portion of the mouth diode 60, and 62 denotes a surface wiring. Reference numeral 63 denotes a back surface wiring of the logic element 60, reference numeral 64 denotes a diaphragm opening for connecting the front surface wiring 62 and the back surface wiring 63, and the opening of the diaphragm 4 of the sensor element shown in the above embodiment. Similarly, insulating resin 19 is filled. The bumps 65 connect the backside wiring 53 of the memory element 50 to the front side wiring 62 of the logic element 60, and the bumps 66 connect the backside wiring 63 of the logic element 60 to the circuit board 13. ing. The mounting and assembling method is the same as in the case of FIG. Finally, the whole is sealed with a mold resin 25. Although the case where two elements are combined has been described as an example, it is naturally possible to connect two or more elements in the same manner. With this structure, a semiconductor device including a plurality of elements can be reduced in size. Industrial applicability

The semiconductor device according to the present invention relates to the structure of a semiconductor device in which the input and output of elements formed on the front surface of a substrate can be taken out from the back surface of the substrate. As an application example, a thermal sensor or the like can be considered. For example, it is used for a flow sensor or a pressure sensor for measuring an intake air amount of an internal combustion engine for a vehicle or the like.

Claims

The scope of the claims

1. On a first surface of a semiconductor substrate, a semiconductor element and first input / output wiring to / from the semiconductor element are provided, and the semiconductor go board of a portion including at least a partial region of the first input / output wiring is provided. Removed to form a diaphragm structure, and the first input / output wiring and the input / output portion formed on the second surface of the semiconductor substrate are connected by a second input / output wiring via the diaphragm structure; A semiconductor device, wherein an insulating resin is provided in a removed portion of the semiconductor substrate on which the diaphragm structure is formed.

2. The semiconductor device according to claim 1, wherein the second input / output wiring and the input / output portion are covered with an insulating resin.

3. The semiconductor device according to claim 1, wherein the semiconductor element includes a thermosensitive resistor, and at least a semiconductor substrate at a portion where the thermosensitive resistor is formed is removed to form a second diaphragm structure. 13. The semiconductor device according to item 9.