JP6045644B2 - Flow sensor and manufacturing method thereof - Google Patents

Description

  The present invention relates to a flow sensor and a manufacturing technique thereof, and more particularly to a technique effective when applied to the structure of a flow sensor.

  Japanese Patent Application Laid-Open No. 2004-74713 (Patent Document 1) discloses a semiconductor package manufacturing method in which a component is clamped by a mold having a release film sheet and a resin is poured.

  Japanese Patent Application Laid-Open No. 2011-122984 (Patent Document 2) uses an insert piece and an elastic film supported by a mold with a spring for a flow rate sensor in which a flow rate detection part of a gas (air) flow is partially exposed. A method for manufacturing a flow sensor is described.

JP 2004-74713 A JP 2011-122984 A

  For example, currently, an internal combustion engine such as an automobile is provided with an electronically controlled fuel injection device. This electronically controlled fuel injection device has the role of operating the internal combustion engine efficiently by appropriately adjusting the amount of gas (air) and fuel flowing into the internal combustion engine. For this reason, in the electronically controlled fuel injection device, it is necessary to accurately grasp the gas (air) flowing into the internal combustion engine. For this reason, the electronic control fuel injection device is provided with a flow rate sensor (air flow sensor) for measuring the flow rate of gas (air).

  Among flow sensors, a flow sensor manufactured by a semiconductor micromachining technique is particularly attracting attention because it can reduce cost and can be driven with low power. Such a flow sensor has, for example, a diaphragm (thin plate portion) formed by anisotropic etching on the back surface of a semiconductor substrate made of silicon, and a heating resistor and a temperature measuring device on the surface of the semiconductor substrate opposite to the diaphragm. The flow rate detection part which consists of a resistor is formed.

  The actual flow sensor includes, for example, a second semiconductor chip formed with a control circuit unit for controlling the flow rate detection unit in addition to the first semiconductor chip formed with a diaphragm and a flow rate detection unit. The first semiconductor chip and the second semiconductor chip described above are mounted on a substrate, for example, and are electrically connected to wiring (terminals) formed on the substrate. Specifically, for example, the first semiconductor chip is connected to a wiring formed on the substrate by a wire made of a gold wire, and the second semiconductor chip uses a bump electrode formed on the second semiconductor chip. , Connected to the wiring formed on the substrate. In this way, the first semiconductor chip and the second semiconductor chip mounted on the substrate are electrically connected via the wiring formed on the substrate. As a result, the flow rate detection unit formed in the first semiconductor chip can be controlled by the control circuit unit formed in the second semiconductor chip, and a flow rate sensor is configured.

  At this time, the gold wire (wire) connecting the first semiconductor chip and the substrate is usually fixed by potting resin in order to prevent contact due to deformation. That is, the gold wire (wire) is covered and fixed by the potting resin, and the gold wire (wire) is protected by the potting resin. On the other hand, the first semiconductor chip and the second semiconductor chip constituting the flow sensor are usually not sealed with potting resin. In other words, a normal flow sensor has a structure in which only a gold wire (wire) is covered with a potting resin.

  Here, the fixing of the gold wire (wire) with the potting resin is not performed in a state in which the first semiconductor chip is fixed with a mold or the like. Therefore, the contraction of the potting resin causes the first semiconductor chip to deviate from the mounting position. There's a problem. Furthermore, since the potting resin is formed by dropping, there is a problem that the dimensional accuracy of the potting resin is low. As a result, the mounting position of the first semiconductor chip on which the flow rate detection unit is formed varies for each individual flow sensor, and the formation position of the potting resin is slightly different. Variations will occur. For this reason, in order to suppress the performance variation of each flow sensor, it is necessary to correct detection performance for every flow sensor, and the necessity of adding the performance correction process in the manufacturing process of a flow sensor arises. In particular, when the performance correction process is lengthened, there is a problem that the throughput in the manufacturing process of the flow sensor is reduced and the cost of the flow sensor is increased. Furthermore, since the potting resin does not promote curing by heating, the time until the potting resin is cured becomes long, and the throughput in the manufacturing process of the flow sensor is reduced.

  An object of the present invention is to provide a technique capable of improving performance by suppressing performance variation for each flow sensor (including a case where reliability is improved and performance improvement is achieved).

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

  A flow rate sensor according to a representative embodiment includes: (a) a first chip mounting portion; and (b) a first semiconductor chip disposed on the first chip mounting portion, wherein the first semiconductor chip is (B1) A flow rate detection unit formed on the main surface of the first semiconductor substrate, and (b2) a region facing the flow rate detection unit among the back surface of the first semiconductor substrate opposite to the main surface. And a diaphragm formed on the substrate. Here, the frame is mounted on the first semiconductor chip and has an opening that exposes at least the flow rate detection unit, and is made of a material having an elastic coefficient smaller than that of the first semiconductor chip. including. Then, a part of the first semiconductor chip is sealed with a sealing body containing a resin in a state where the flow rate detection part formed in the first semiconductor chip is exposed from the opening of the frame body. It is what.

  Moreover, the manufacturing method of the flow sensor in typical embodiment is a manufacturing method of the flow sensor which has the structure mentioned above. And (a) preparing a base material having the first chip mounting portion; (b) preparing a first semiconductor chip; and (c) the first semiconductor on the first chip mounting portion. And a step of mounting a chip. Thereafter, (d) after the step (c), the step of disposing the frame body on the first semiconductor chip so that the flow rate detection unit is included in the opening formed in the frame body; (E) After the step (d), the step of sealing a part of the first semiconductor chip with the sealing body while exposing the flow rate detection part formed in the first semiconductor chip; Is provided. Here, the step (e) includes (e1) a step of preparing an upper die and a lower die, and (e2) after the step (e1), the bottom surface of the upper die is brought into close contact with the frame body. Accordingly, the step of sandwiching the base material on which the first semiconductor chip is mounted via the second space between the upper mold and the lower mold while forming the first space surrounding the flow rate detection unit. And (e3) a step of pouring the resin into the second space after the step (e2).

  Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

  It is possible to improve performance by suppressing performance variation for each flow sensor.

FIG. 3 is a circuit block diagram showing a circuit configuration of the flow sensor in the first embodiment. FIG. 3 is a plan view showing a layout configuration of a semiconductor chip that constitutes a part of the flow sensor in the first embodiment. It is a figure which shows the mounting structure of the flow sensor in Embodiment 1, and is a figure which shows the structure before sealing with resin. In particular, (a) is a plan view showing the mounting configuration of the flow sensor in the first embodiment, (b) is a cross-sectional view taken along line AA in (a), and (c) is It is a top view which shows the back surface of a semiconductor chip. (A) is a top view which shows the structure of a frame, (b) is sectional drawing cut | disconnected by the AA line of (a), (c) is the BB line of (a). It is sectional drawing cut | disconnected by. It is a figure which shows the mounting structure of the flow sensor in Embodiment 1, and is a figure which shows the structure after sealing with resin. In particular, (a) is a plan view showing the mounting configuration of the flow sensor in the first embodiment, (b) is a cross-sectional view taken along line AA in (a), and (c) is ( It is sectional drawing cut | disconnected by the BB line of a). It is a top view which shows the mounting structure of the flow sensor after removing a dam bar. FIG. 6 is a cross-sectional view showing a manufacturing process of the flow sensor in the first embodiment. FIG. 8 is a cross-sectional view showing the flow sensor manufacturing process following FIG. 7. It is sectional drawing which shows the manufacturing process of the flow sensor following FIG. FIG. 10 is a cross-sectional view showing a flow sensor manufacturing process following FIG. 9. FIG. 11 is a cross-sectional view showing a manufacturing process of the flow sensor following FIG. 10. FIG. 12 is a cross-sectional view showing a manufacturing process of the flow sensor following FIG. 11. It is sectional drawing which shows the example which presses an upper metal mold | die with respect to the lead frame which mounts a semiconductor chip, interposing only a frame, without using an elastic film. It is a figure which shows an example of the related technique of resin sealing, without using a frame. (A) is a top view which shows the flow sensor in the modification 1, (b) is sectional drawing cut | disconnected by the AA line of (a), (c) is B- of (a). It is sectional drawing cut | disconnected by the B line. It is a figure which shows one cross section of the flow sensor in the modification 1. In the modification 2, it is a top view which shows the structure of the flow sensor before resin sealing. It is sectional drawing cut | disconnected by the AA line of FIG. It is sectional drawing cut | disconnected by the BB line of FIG. It is a figure which shows the mounting structure of the flow sensor in Embodiment 2, and is a figure which shows the structure before sealing with resin. In particular, (a) is a plan view showing the mounting configuration of the flow sensor in the second embodiment, (b) is a cross-sectional view taken along line AA in (a), and (c) is It is sectional drawing cut | disconnected by the BB line of (a), (d) is a top view which shows the back surface of a semiconductor chip. It is a figure which shows the mounting structure of the flow sensor in Embodiment 2, and is a figure which shows the structure after sealing with resin. In particular, (a) is a plan view showing the mounting configuration of the flow sensor in the second embodiment, (b) is a cross-sectional view taken along line AA in (a), and (c) is ( It is sectional drawing cut | disconnected by the BB line of a). It is a top view which shows the mounting structure of the flow sensor after removing a dam bar. FIG. 10 is a cross-sectional view showing a manufacturing process of the flow sensor in the second embodiment. FIG. 24 is a cross-sectional view showing the flow rate sensor manufacturing process following FIG. 23. FIG. 25 is a cross-sectional view showing the flow rate sensor manufacturing process following FIG. 24. FIG. 26 is a cross-sectional view showing the flow rate sensor manufacturing process following FIG. 25.

  In the following embodiments, when it is necessary for the sake of convenience, the description will be divided into a plurality of sections or embodiments. However, unless otherwise specified, they are not irrelevant to each other. There are some or all of the modifications, details, supplementary explanations, and the like.

  Further, in the following embodiments, when referring to the number of elements (including the number, numerical value, quantity, range, etc.), especially when clearly indicated and when clearly limited to a specific number in principle, etc. Except, it is not limited to the specific number, and may be more or less than the specific number.

  Further, in the following embodiments, the constituent elements (including element steps and the like) are not necessarily indispensable unless otherwise specified and apparently essential in principle. Needless to say.

  Similarly, in the following embodiments, when referring to the shape, positional relationship, etc., of components, etc., unless otherwise specified, and in principle, it is considered that this is not clearly the case, it is substantially the same. Including those that are approximate or similar to the shape. The same applies to the above numerical values and ranges.

  In all the drawings for explaining the embodiments, the same members are denoted by the same reference symbols in principle, and the repeated explanation thereof is omitted. In order to make the drawings easy to understand, even a plan view may be hatched.

(Embodiment 1)
<Circuit configuration of flow sensor>
First, the circuit configuration of the flow sensor will be described. FIG. 1 is a circuit block diagram showing a circuit configuration of the flow sensor according to the first embodiment. In FIG. 1, the flow sensor in the first embodiment has a CPU (Central Processing Unit) 1 for controlling the flow sensor, and an input circuit 2 for inputting an input signal to the CPU 1. And it has the output circuit 3 for outputting the output signal from CPU1. The flow rate sensor is provided with a memory 4 for storing data, and the CPU 1 can access the memory 4 and refer to the data stored in the memory 4.

  Next, the CPU 1 is connected to the base electrode of the transistor Tr via the output circuit 3. The collector electrode of the transistor Tr is connected to the power source PS, and the emitter electrode of the transistor Tr is connected to the ground (GND) via the heating resistor HR. Therefore, the transistor Tr is controlled by the CPU 1. That is, since the base electrode of the transistor Tr is connected to the CPU 1 via the output circuit 3, an output signal from the CPU 1 is input to the base electrode of the transistor Tr.

  As a result, the current flowing through the transistor Tr is controlled by an output signal (control signal) from the CPU 1. When the current flowing through the transistor Tr is increased by the output signal from the CPU 1, the current supplied from the power source PS to the heating resistor HR is increased, and the heating amount of the heating resistor HR is increased.

  On the other hand, when the current flowing through the transistor Tr decreases due to the output signal from the CPU 1, the current supplied to the heating resistor HR decreases, and the heating amount of the heating resistor HR decreases.

  As described above, the flow rate sensor according to the first embodiment is configured such that the amount of current flowing through the heating resistor HR is controlled by the CPU 1 and the amount of heat generated from the heating resistor HR is thereby controlled by the CPU 1. I understand that.

  Subsequently, in the flow rate sensor according to the first embodiment, a heater control bridge HCB is provided in order for the CPU 1 to control the current flowing through the heating resistor HR. The heater control bridge HCB is configured to detect the amount of heat released from the heating resistor HR and output the detection result to the input circuit 2. As a result, the CPU 1 can input the detection result from the heater control bridge HCB, and controls the current flowing through the transistor Tr based on this.

  Specifically, as shown in FIG. 1, the heater control bridge HCB includes resistors R1 to R4 that form a bridge between the reference voltage Vref1 and the ground (GND). In the heater control bridge HCB configured as described above, when the gas heated by the heating resistor HR is higher than the intake air temperature by a certain temperature (ΔT, for example, 100 ° C.), the potential of the node A and the node B The resistance values of the resistors R1 to R4 are set so that the potential difference between the potentials of the resistors R1 to R4 is 0V. That is, the resistors R1 to R4 constituting the heater control bridge HCB are referred to as a component in which the resistor R1 and the resistor R3 are connected in series and a component in which the resistor R2 and the resistor R4 are connected in series. The bridge is configured so as to be connected in parallel between the voltage Vref1 and the ground (GND). A connection point between the resistor R1 and the resistor R3 is a node A, and a connection point between the resistor R2 and the resistor R4 is a node B.

  At this time, the gas heated by the heating resistor HR comes into contact with the resistor R1 constituting the heater control bridge HCB. Therefore, the resistance value of the resistor R1 constituting the heater control bridge HCB mainly changes depending on the amount of heat generated from the heating resistor HR. When the resistance value of the resistor R1 changes in this way, the potential difference between the node A and the node B changes. Since the potential difference between the node A and the node B is input to the CPU 1 via the input circuit 2, the CPU 1 controls the current flowing through the transistor Tr based on the potential difference between the node A and the node B.

  Specifically, the CPU 1 controls the amount of heat generated from the heating resistor HR by controlling the current flowing through the transistor Tr so that the potential difference between the node A and the node B becomes 0V. That is, in the flow rate sensor according to the first embodiment, the CPU 1 causes the gas heated by the heating resistor HR to be only a certain temperature (ΔT, for example, 100 ° C.) higher than the intake air temperature based on the output of the heater control bridge HCB. It can be seen that the feedback control is performed so as to maintain a high constant value.

  Subsequently, the flow sensor in the first embodiment has a temperature sensor bridge TSB for detecting the gas flow rate. The temperature sensor bridge TSB is composed of four temperature measuring resistors that form a bridge between the reference voltage Vref2 and the ground (GND). The four resistance temperature detectors are composed of two upstream resistance temperature detectors UR1 and UR2, and two downstream resistance temperature detectors BR1 and BR2.

  That is, the direction of the arrow in FIG. 1 indicates the direction in which the gas flows. The upstream resistance thermometers UR1 and UR2 are provided on the upstream side of the gas flow direction, and the downstream resistance thermometers BR1 and BR2 is provided. The upstream resistance thermometers UR1 and UR2 and the downstream resistance thermometers BR1 and BR2 are arranged so that the distance to the heating resistor HR is the same.

  In the temperature sensor bridge TSB, an upstream resistance temperature detector UR1 and a downstream resistance temperature detector BR1 are connected in series between the reference voltage Vref2 and the ground (GND), and the upstream resistance temperature detector UR1 and the downstream resistance temperature detector. The connection point of BR1 is node C.

  On the other hand, an upstream resistance temperature detector UR2 and a downstream resistance temperature detector BR2 are connected in series between the ground (GND) and the reference voltage Vref2, and a connection point between the upstream resistance temperature detector UR2 and the downstream resistance temperature detector BR2. Is node D. Then, the potential of the node C and the potential of the node D are configured to be input to the CPU 1 via the input circuit 2. The upstream resistance thermometers UR1 and UR2 and the downstream temperature sensor are set so that the potential difference between the potential of the node C and the potential of the node D becomes 0V when the flow rate of the gas flowing in the arrow direction is zero. Each resistance value of the resistors BR1 and BR2 is set.

  Specifically, the upstream resistance thermometers UR1 and UR2 and the downstream resistance thermometers BR1 and BR2 are configured to have the same distance from the heating resistor HR and the same resistance value. For this reason, it can be seen that the temperature sensor bridge TSB is configured such that the potential difference between the node C and the node D is 0 V in the absence of wind regardless of the amount of heat generated by the heating resistor HR.

<Flow sensor operation>
The flow sensor according to the first embodiment is configured as described above, and the operation thereof will be described below with reference to FIG. First, the CPU 1 outputs an output signal (control signal) to the base electrode of the transistor Tr via the output circuit 3, thereby causing a current to flow through the transistor Tr. Then, a current flows from the power supply PS connected to the collector electrode of the transistor Tr to the heating resistor HR connected to the emitter electrode of the transistor Tr. For this reason, the heating resistor HR generates heat. The gas heated by the heat generated from the heat generating resistor HR heats the resistor R1 constituting the heater control bridge HCB.

  At this time, when the gas heated by the heating resistor HR is increased by a certain temperature (for example, 100 ° C.), the resistor is set so that the potential difference between the node A and the node B of the heater control bridge HCB becomes 0V. Each resistance value of R1 to R4 is set. For this reason, for example, when the gas heated by the heating resistor HR is increased by a certain temperature (for example, 100 ° C.), the potential difference between the node A and the node B of the heater control bridge HCB becomes 0V, This difference potential (0 V) is input to the CPU 1 via the input circuit 2. Then, the CPU 1 recognizing that the difference potential from the heater control bridge HCB is 0 V outputs an output signal (control signal) for maintaining the current amount of current to the base electrode of the transistor Tr via the output circuit 3. Output.

  On the other hand, when the gas heated by the heating resistor HR deviates from a certain temperature (for example, 100 ° C.), a non-zero potential difference is generated between the node A and the node B of the heater control bridge HCB. The difference potential is input to the CPU 1 via the input circuit 2. Then, the CPU 1 recognizing that the difference potential from the heater control bridge HCB is generated, outputs an output signal (control signal) to the base electrode of the transistor Tr via the output circuit 3 so that the difference potential becomes 0V. Output.

  For example, when a potential difference in a direction in which the gas heated by the heating resistor HR becomes higher than a certain temperature (for example, 100 ° C.) is generated, the CPU 1 controls the control signal so that the current flowing through the transistor Tr decreases. (Output signal) is output to the base electrode of the transistor Tr. On the other hand, when a potential difference in a direction in which the gas heated by the heating resistor HR becomes lower than a certain temperature (for example, 100 ° C.) is generated, the CPU 1 increases the current flowing through the transistor Tr. A control signal (output signal) is output to the base electrode of the transistor Tr.

  As described above, the CPU 1 performs feedback control based on the output signal from the heater control bridge HCB so that the potential difference between the node A and the node B of the heater control bridge HCB is 0 V (equilibrium state). To do. From this, it can be seen that in the flow rate sensor according to the first embodiment, the gas heated by the heating resistor HR is controlled to have a constant temperature.

  Next, an operation for measuring the gas flow rate in the flow sensor according to the first embodiment will be described. First, the case of a windless state will be described. When the flow rate of the gas flowing in the direction of the arrow is zero, the upstream resistance temperature detectors UR1 and UR2 are set so that the potential difference between the node C potential and the node D potential of the temperature sensor bridge TSB becomes 0V. Each resistance value of the downstream resistance thermometers BR1 and BR2 is set.

  Specifically, the upstream resistance thermometers UR1 and UR2 and the downstream resistance thermometers BR1 and BR2 are configured to have the same distance from the heating resistor HR and the same resistance value. Therefore, in the temperature sensor bridge TSB, regardless of the amount of heat generated by the heating resistor HR, if there is no wind, the difference potential between the node C and the node D becomes 0V, and this difference potential (0V) is passed through the input circuit 2. Are input to the CPU 1. Then, the CPU 1 recognizing that the potential difference from the temperature sensor bridge TSB is 0 V recognizes that the flow rate of the gas flowing in the direction of the arrow is zero, and the gas flow rate Q is zero via the output circuit 3. Is output from the flow sensor in the first embodiment.

  Next, consider the case where gas is flowing in the direction of the arrow in FIG. In this case, as shown in FIG. 1, the upstream resistance temperature detectors UR1 and UR2 arranged on the upstream side in the gas flow direction are cooled by the gas flowing in the arrow direction. For this reason, the temperature of the upstream resistance thermometers UR1 and UR2 decreases. On the other hand, the downstream resistance thermometers BR1 and BR2 arranged on the downstream side in the gas flow direction have a temperature because the gas heated by the heating resistor HR flows to the downstream resistance thermometers BR1 and BR2. Rises. As a result, the balance of the temperature sensor bridge TSB is lost, and a non-zero differential potential is generated between the node C and the node D of the temperature sensor bridge TSB.

  This difference potential is input to the CPU 1 via the input circuit 2. Then, the CPU 1 recognizing that the potential difference from the temperature sensor bridge TSB is not zero recognizes that the flow rate of the gas flowing in the arrow direction is not zero. Thereafter, the CPU 1 accesses the memory 4. Since the memory 4 stores a comparison table (table) in which the difference potential and the gas flow rate are associated with each other, the CPU 1 accessing the memory 4 calculates the gas flow rate Q from the comparison table stored in the memory 4. . In this way, the gas flow rate Q calculated by the CPU 1 is output from the flow rate sensor in the first embodiment via the output circuit 3. As described above, according to the flow rate sensor of the first embodiment, it can be seen that the flow rate of gas can be obtained.

<Flow sensor layout configuration>
Next, the layout configuration of the flow sensor according to the first embodiment will be described. For example, the flow sensor in the first embodiment shown in FIG. 1 is formed on two semiconductor chips. Specifically, the heating resistor HR, the heater control bridge HCB, and the temperature sensor bridge TSB are formed on one semiconductor chip, and the CPU 1, the input circuit 2, the output circuit 3, the memory 4, and the like are formed on another semiconductor chip. . Hereinafter, a layout configuration of a semiconductor chip on which the heating resistor HR, the heater control bridge HCB, and the temperature sensor bridge TSB are formed will be described.

  FIG. 2 is a plan view showing a layout configuration of the semiconductor chip CHP1 constituting a part of the flow sensor according to the first embodiment. First, as shown in FIG. 2, the semiconductor chip CHP1 has a rectangular shape, and gas flows from the left side to the right side (arrow direction) of the semiconductor chip CHP1. As shown in FIG. 2, a rectangular diaphragm DF is formed on the back surface side of the rectangular semiconductor chip CHP1. The diaphragm DF indicates a thin plate region where the thickness of the semiconductor chip CHP1 is reduced. That is, the thickness of the region where the diaphragm DF is formed is thinner than the thickness of the other semiconductor chip CHP1.

  As shown in FIG. 2, a flow rate detection unit FDU is formed in the surface region of the semiconductor chip CHP1 opposite to the back surface region where the diaphragm DF is formed. Specifically, a heating resistor HR is formed at the center of the flow rate detection unit FDU, and a resistor R1 that forms a heater control bridge is formed around the heating resistor HR. And the resistor R2-R4 which comprises a heater control bridge is formed in the outer side of the flow volume detection part FDU. A heater control bridge is configured by the resistors R1 to R4 formed in this way.

  In particular, since the resistor R1 constituting the heater control bridge is formed in the vicinity of the heating resistor HR, the temperature of the gas heated by the heat generated from the heating resistor HR is accurately reflected in the resistor R1. Can do.

  On the other hand, since the resistors R2 to R4 constituting the heater control bridge are arranged apart from the heating resistor HR, they can be made less susceptible to the heat generated by the heating resistor HR.

  Therefore, the resistor R1 can be configured to react sensitively to the temperature of the gas heated by the heating resistor HR, and the resistors R2 to R4 are not easily affected by the heating resistor HR and have a constant resistance value. The value can be easily maintained. For this reason, the detection accuracy of the heater control bridge can be increased.

  Further, upstream temperature measuring resistors UR1 and UR2 and downstream temperature measuring resistors BR1 and BR2 are arranged so as to sandwich the heating resistor HR formed in the flow rate detection unit FDU. Specifically, upstream resistance thermometers UR1 and UR2 are formed on the upstream side in the arrow direction in which gas flows, and downstream resistance thermometers BR1 and BR2 are formed in the downstream in the arrow direction in which gas flows.

  With this configuration, when the gas flows in the direction of the arrow, the temperature of the upstream resistance thermometers UR1 and UR2 can be lowered and the temperature of the downstream resistance thermometers BR1 and BR2 can be increased. . Thus, the temperature sensor bridge is formed by the upstream resistance thermometers UR1 and UR2 and the downstream resistance thermometers BR1 and BR2 arranged in the flow rate detection unit FDU.

  The heating resistor HR, the upstream resistance thermometers UR1 and UR2, and the downstream resistance thermometers BR1 and BR2 are formed by sputtering a metal film such as platinum or a semiconductor thin film such as polysilicon (polycrystalline silicon), for example. It can be formed by patterning by a method such as ion etching after forming by a method such as the CVD method or the CVD (Chemical Vapor Deposition) method.

  The heating resistor HR configured as described above, the resistors R1 to R4 constituting the heater control bridge, and the upstream temperature sensing resistors UR1 and UR2 and the downstream temperature sensing resistors BR1 and BR2 constituting the temperature sensor bridge are: These are connected to the wiring WL1 and drawn out to the pads PD1 arranged along the lower side of the semiconductor chip CHP1.

  As described above, the semiconductor chip CHP1 constituting a part of the flow sensor according to the first embodiment is laid out. The actual flow rate sensor includes one semiconductor chip on which the heating resistor HR, the heater control bridge HCB and the temperature sensor bridge TSB are formed, and another one on which the CPU 1, the input circuit 2, the output circuit 3, the memory 4, and the like are formed. The semiconductor chip has a structure in which these semiconductor chips are mounted on a substrate.

  Below, the flow sensor in this Embodiment 1 comprised in this way is demonstrated.

<Mounting configuration of flow sensor in embodiment 1>
FIG. 3 is a diagram showing a mounting configuration of the flow sensor FS1 in the first embodiment, and is a diagram showing a configuration before sealing with resin. In particular, FIG. 3A is a plan view showing a mounting configuration of the flow sensor FS1 in the first embodiment. 3B is a cross-sectional view taken along line AA in FIG. 3A, and FIG. 3C is a plan view showing the back surface of the semiconductor chip CHP1.

  First, as shown in FIG. 3A, the flow sensor FS1 in the first embodiment has a lead frame LF made of, for example, a copper material. The lead frame LF includes a chip mounting portion TAB1 and a chip mounting portion TAB2 inside the dam bar DM constituting the outer frame body. The semiconductor chip CHP1 is mounted on the chip mounting portion TAB1, and the semiconductor chip CHP2 is mounted on the chip mounting portion TAB2.

  The semiconductor chip CHP1 has a rectangular shape, and a flow rate detection unit FDU is formed substantially at the center. A wiring WL1 connected to the flow rate detection unit FDU is formed on the semiconductor chip CHP1, and the wiring WL1 is connected to a plurality of pads PD1 formed along one side of the semiconductor chip CHP1. That is, the flow rate detection unit FDU and the plurality of pads PD1 are connected by the wiring WL1. These pads PD1 are connected to a lead LD1 formed on the lead frame LF via a wire W1 made of, for example, a gold wire. The lead LD1 formed on the lead frame LF is further connected to a pad PD2 formed on the semiconductor chip CHP2 via a wire W2 made of, for example, a gold wire.

  On the semiconductor chip CHP2, an integrated circuit made of semiconductor elements such as MISFET (Metal Insulator Semiconductor Field Effect Transistor) and wirings is formed. Specifically, an integrated circuit constituting the CPU 1, the input circuit 2, the output circuit 3 or the memory 4 shown in FIG. 1 is formed. These integrated circuits are connected to the pads PD2 and PD3 that function as external connection terminals. The pad PD3 formed on the semiconductor chip CHP2 is connected to the lead LD2 formed on the lead frame LF via a wire W3 made of, for example, a gold wire. In this manner, the semiconductor chip CHP1 in which the flow rate detection unit FDU is formed and the semiconductor chip CHP2 in which the control circuit is formed are connected via the leads LD1 formed in the lead frame LF. Recognize. Although not shown in FIG. 3, a polyimide film is formed on the outermost surface of the semiconductor chip CHP1 for the purpose of stress buffering with the resin to be bonded, surface protection, insulation, etc., as will be described later. May be.

  Subsequently, as shown in FIG. 3B, a chip mounting portion TAB1 is formed on the lead frame LF, and the semiconductor chip CHP1 is mounted on the chip mounting portion TAB1. The semiconductor chip CHP1 is bonded to the chip mounting portion TAB1 with an adhesive ADH1. A diaphragm DF (thin plate portion) is formed on the back surface of the semiconductor chip CHP1, and a flow rate detection unit FDU is formed on the surface of the semiconductor chip CHP1 facing the diaphragm DF. On the other hand, an opening OP1 is formed at the bottom of the chip mounting portion TAB1 existing below the diaphragm DF. Here, an example is shown in which the opening OP1 is formed at the bottom of the chip mounting portion TAB1 existing below the diaphragm DF, but the technical idea in the first embodiment is not limited to this. A lead frame LF in which the opening OP1 is not formed can also be used.

  Further, as shown in FIG. 3B, on the surface (upper surface) of the semiconductor chip CHP1, in addition to the flow rate detection unit FDU, a pad PD1 connected to the flow rate detection unit FDU is formed, and this pad PD1 Is connected to a lead LD1 formed on the lead frame LF via a wire W1. In addition to the semiconductor chip CHP1, the semiconductor chip CHP2 is also mounted on the lead frame LF, and the semiconductor chip CHP2 is bonded to the chip mounting portion TAB2 with an adhesive ADH2. Further, the pad PD2 formed on the semiconductor chip CHP2 and the lead LD1 formed on the lead frame LF are connected via a wire W2. Further, the pad PD3 formed on the semiconductor chip CHP2 and the lead LD2 formed on the lead frame LF are electrically connected through a wire W3.

  The adhesive ADH1 that bonds the semiconductor chip CHP1 and the chip mounting portion TAB1 and the adhesive ADH2 that bonds the semiconductor chip CHP2 and the chip mounting portion TAB2 are, for example, thermosetting such as epoxy resin or polyurethane resin. An adhesive having a resin as a component and an adhesive having a thermoplastic resin such as a polyimide resin, an acrylic resin, or a fluororesin as a component can be used.

  For example, the semiconductor chip CHP1 and the chip mounting portion TAB1 can be bonded by applying an adhesive ADH1 or a silver paste as shown in FIG. 3C, or by using a sheet-like adhesive. FIG. 3C is a plan view showing the back surface of the semiconductor chip CHP1. As shown in FIG. 3C, a diaphragm DF is formed on the back surface of the semiconductor chip CHP1, and an adhesive ADH1 is applied so as to surround the diaphragm DF. FIG. 3C shows an example in which the adhesive ADH1 is applied so as to surround the diaphragm DF in a square shape. However, the present invention is not limited to this. For example, the diaphragm DF is surrounded by an arbitrary shape such as an elliptical shape. As described above, the adhesive ADH1 may be applied.

  Furthermore, in the first embodiment, as shown in FIGS. 3A and 3B, the frame body FB is formed on a part of the semiconductor chip CHP1. The frame body FB has, for example, a rectangular shape, and has an opening OP (FB) formed therein. The frame body FB is arranged so that the flow rate detection unit FDU formed on the main surface of the semiconductor chip CHP1 is exposed from the opening OP (FB), and the semiconductor chip CHP1 is disposed outside the frame body FB. The plurality of formed pads PD1 are arranged so as to be exposed.

  Below, the structure of this frame FB is demonstrated. FIG. 4 is a diagram illustrating a configuration of the frame FB. 4A is a plan view showing the configuration of the frame FB, and FIG. 4B is a cross-sectional view taken along the line AA in FIG. 4A. Moreover, FIG.4 (c) is sectional drawing cut | disconnected by the BB line of Fig.4 (a).

  As shown in FIG. 4A, the frame FB has a rectangular shape, and it can be seen that the opening OP (FB) is formed inside the frame FP. As shown in FIGS. 4B and 4C, the frame FB is formed with a wall portion WP parallel to the side surface of the semiconductor chip CHP1. As shown in FIG. 3B, the frame FB can be disposed on the semiconductor chip CHP1 in a state of being aligned with the semiconductor chip CHP1 by bringing the wall portion WP into close contact with the semiconductor chip CHP1. . At this time, the frame FB may be bonded to the semiconductor chip CHP1, or may not be bonded to the semiconductor chip CHP1. In particular, when the frame FB is bonded to the semiconductor chip CHP1, it is possible to obtain an effect that can prevent the frame FB from being displaced. Note that the wall portion WP formed in the frame body FB may be provided corresponding to at least one side surface of the semiconductor chip CHP1.

  Here, the feature of the frame FB in the first embodiment is that the elastic coefficient of the material constituting the frame FB is smaller than the elastic coefficient of the material constituting the semiconductor chip CHP1. At this time, the elastic modulus means the elastic modulus of the frame FB and the semiconductor chip CHP1. The elastic modulus is a proportional constant when the Hooke's law that stress and strain in an elastic body are proportional to each other is expressed in the form of “stress is proportional to strain”.

  For example, the elastic coefficient of the frame FB and the elastic coefficient of the semiconductor chip CHP1 are desirably compared at a temperature of 25 ° C. (room temperature). Further, the comparison of the elastic coefficients can be performed between the elastic coefficient of the frame FB and the elastic coefficient of the base material constituting the semiconductor chip CHP1. For example, when the base material constituting the semiconductor chip CHP1 is made of a silicon single crystal, the frame FB can be made of a material having a smaller elastic coefficient at room temperature than the silicon single crystal.

  Although the comparison of the elastic modulus between the frame FB and the semiconductor chip CHP1 has been described above, the basic idea is that the frame FB is softer than the semiconductor chip CHP1. The hardness referred to here can be compared by, for example, any of Vickers hardness at room temperature, micro Vickers hardness, Brinell hardness, or Rockwell hardness.

  Specifically, the frame FB, which is softer than the semiconductor chip CHP1, is made of a thermoplastic resin, an epoxy resin, a phenol resin, or the like containing PBT resin, ABS resin, PC resin, nylon resin, PS resin, fluorine resin, or the like as a component. It is possible to use a thermosetting resin containing as a component, a rubber material containing Teflon (registered trademark), urethane, fluorine or the like as a component, or a polymer material such as an elastomer.

  The frame body FB can be formed by filling a mold with a resin by injection molding or transfer molding and molding, or a film product or a sheet-shaped product formed from the above-described materials can be used. .

  Further, the frame FB formed from a polymer material such as a thermosetting resin, a thermoplastic resin, a rubber material, or an elastomer can also be used as an adhesive having the adhesiveness of the frame FB itself. An inorganic filler such as glass, silica, mica and talc, and an organic filler such as carbon can also be filled.

  Note that the frame body FB can also be configured by forming a metal material having a smaller elastic coefficient than silicon, such as brass, aluminum alloy, or copper alloy, by pressing, rolling, or casting.

  In the flow sensor FS1 according to the first embodiment, the mounting configuration of the flow sensor FS1 before sealing with resin is configured as described above, and the mounting configuration of the flow sensor FS1 after sealing with resin is described below. Will be described.

  FIG. 5 is a diagram showing a mounting configuration of the flow sensor FS1 in the first embodiment, and is a diagram showing a configuration after sealing with resin. In particular, FIG. 5A is a plan view showing the mounting configuration of the flow sensor FS1 in the first embodiment. 5B is a cross-sectional view taken along the line AA in FIG. 5A, and FIG. 5C is a cross-sectional view taken along the line BB in FIG. 5A.

  In the flow rate sensor FS1 in the first embodiment, as shown in FIG. 5A, the flow rate detection unit FDU formed in the semiconductor chip CHP1 is exposed from the opening OP (FB) formed in the frame body FB. In this state, a part of the semiconductor chip CHP1 and the entire semiconductor chip CHP2 are covered with the resin MR (first feature point). That is, in the first embodiment, the region of the semiconductor chip CHP1 and the entire region of the semiconductor chip CHP2 except the region where the flow rate detection unit FDU is formed and the region where the frame body FB is mounted are collectively made of resin MR. It is sealed.

  As the above-described resin MR, for example, a thermosetting resin such as an epoxy resin or a phenol resin, or a thermoplastic resin such as polycarbonate or polyethylene terephthalate can be used, and a filler such as glass or mica is mixed in the resin. You can also.

  The sealing with the resin MR can be performed in a state in which the semiconductor chip CHP1 in which the flow rate detection unit FDU is formed is fixed by a mold, and therefore, the semiconductor chip CHP1 can be prevented from being displaced and one of the semiconductor chips CHP1 is suppressed. The part and the semiconductor chip CHP2 can be sealed with the resin MR. This means that according to the flow sensor FS1 in the first embodiment, a part of the semiconductor chip CHP1 and the entire region of the semiconductor chip CHP2 can be sealed with the resin MR while suppressing the displacement of each flow sensor FS1. This means that variation in the position of the flow rate detection unit FDU formed in the semiconductor chip CHP1 can be suppressed.

  As a result, according to the first embodiment, the position of the flow rate detection unit FDU that detects the flow rate of gas can be matched by each flow rate sensor FS1, so that there is performance variation in detecting the gas flow rate in each flow rate sensor FS1. The remarkable effect which can be suppressed can be acquired.

  Subsequently, in the flow rate sensor FS1 in the first embodiment, as shown in FIG. 5B, the height of the frame FB on both sides surrounding the exposed flow rate detection unit FDU, or the resin MR (sealing) The height of the stop body is higher than the height of the surface of the semiconductor chip CHP1 including the flow rate detection unit FDU (second feature point). That is, the exposed flow rate detection unit FDU is surrounded by the frame FB, and the height of the frame FB surrounding the flow rate detection unit FDU is higher than the height of the flow rate detection unit FDU. According to the second feature point in the first embodiment, since the component can be prevented from colliding with the exposed flow rate detection unit FDU at the time of mounting and assembly of the component, the semiconductor in which the flow rate detection unit FDU is formed. Breakage of the chip CHP1 can be prevented. In other words, the height of the frame FB surrounding the flow rate detection unit FDU is higher than the height of the exposed flow rate detection unit FDU. For this reason, when the component contacts, first, since it contacts the frame body FB having a high height, the exposed surface (XY surface) of the semiconductor chip CHP1 including the low flow rate detection unit FDU contacts the component, It is possible to prevent the semiconductor chip CHP1 from being damaged.

  In particular, in the first embodiment, the frame FB is disposed on a part of the semiconductor chip CHP1, and the elastic coefficient of the frame FB is smaller than the elastic coefficient of the semiconductor chip CHP1. In other words, the frame FB is made of a softer material than the semiconductor chip CHP1. Therefore, when the component comes into contact with the frame FB, the shock can be absorbed by the deformation of the relatively soft frame FB. Therefore, the impact is applied to the semiconductor chip CHP1 disposed under the frame FB. It is possible to suppress the transmission, and thereby it is possible to effectively prevent the semiconductor chip CHP1 from being damaged.

  Note that the height of the frame body FB and the resin MR (sealing body) need only be higher than the height of the surface of the semiconductor chip CHP1 including the flow rate detection unit FDU, and the height of the frame body FB is the resin MR (sealing body). It may be higher or lower than the height of the body, or may be flush.

  In the first embodiment, in order to prevent the resin MR from entering the inner space of the diaphragm DF, for example, the adhesive ADH1 is applied so as to surround the diaphragm DF formed on the back surface of the semiconductor chip CHP1. It is premised on taking the composition to do. Then, as shown in FIGS. 5B and 5C, an opening OP1 is formed at the bottom of the chip mounting portion TAB1 below the diaphragm DF formed on the back surface of the semiconductor chip CHP1, and further, the chip An opening OP2 is provided in the resin MR that covers the back surface of the mounting portion TAB1.

  As a result, according to the flow sensor FS1 according to the first embodiment, the internal space of the diaphragm DF flows through the opening OP1 formed in the bottom of the chip mounting portion TAB1 and the opening OP2 formed in the resin MR. It communicates with the external space of the sensor FS1. As a result, the pressure in the inner space of the diaphragm DF and the pressure in the outer space of the flow rate sensor FS1 can be made equal, and it is possible to suppress the stress from being applied to the diaphragm DF.

  As described above, the flow sensor FS1 according to the first embodiment is mounted and configured. However, in the actual flow sensor FS1, after sealing with the resin MR, the dam bar DM constituting the outer frame of the lead frame LF. Is removed. FIG. 6 is a plan view showing a mounting configuration of the flow sensor FS1 after the dam bar DM is removed. As shown in FIG. 6, it can be seen that by cutting the dam bar DM, a plurality of electrical signals can be taken out independently from the plurality of leads LD2.

<Method for Manufacturing Flow Sensor in First Embodiment>
The flow sensor FS1 in the first embodiment is configured as described above, and the manufacturing method thereof will be described below with reference to FIGS. 7 to 14 show a manufacturing process in a cross section taken along line AA in FIG.

  First, as shown in FIG. 7, for example, a lead frame LF made of a copper material is prepared. In the lead frame LF, a chip mounting portion TAB1, a chip mounting portion TAB2, a lead LD1, and a lead LD2 are integrally formed, and an opening OP1 is formed at the bottom of the chip mounting portion TAB1.

  Subsequently, as shown in FIG. 8, the semiconductor chip CHP1 is mounted on the chip mounting portion TAB1, and the semiconductor chip CHP2 is mounted on the chip mounting portion TAB2. Specifically, the semiconductor chip CHP1 is connected to the chip mounting portion TAB1 formed on the lead frame LF with an adhesive ADH1. At this time, the semiconductor chip CHP1 is mounted on the chip mounting portion TAB1 so that the diaphragm DF formed on the semiconductor chip CHP1 communicates with the opening OP1 formed at the bottom of the chip mounting portion TAB1. The semiconductor chip CHP1 is formed with a flow rate detection unit FDU, wiring (not shown), and a pad PD1 by a normal semiconductor manufacturing process. And the diaphragm DF is formed in the position of the back surface facing the flow volume detection part FDU formed in the surface of the semiconductor chip CHP1 by anisotropic etching, for example. A semiconductor chip CHP2 is also mounted on the chip mounting portion TAB2 formed on the lead frame LF by an adhesive ADH2. In the semiconductor chip CHP2, semiconductor elements (not shown) such as MISFETs, wirings (not shown), pads PD2, and pads PD3 are formed in advance by a normal semiconductor manufacturing process.

  Next, as shown in FIG. 9, the pad PD1 formed on the semiconductor chip CHP1 and the lead LD1 formed on the lead frame LF are connected by a wire W1 (wire bonding). Similarly, the pad PD2 formed on the semiconductor chip CHP2 is connected to the lead LD1 and the wire W2, and the pad PD3 formed on the semiconductor chip CHP2 is connected to the lead LD2 and the wire W3. The wires W1 to W3 are made of, for example, a gold wire.

  Thereafter, as shown in FIG. 10, the frame body FB is mounted on the semiconductor chip CHP1. Specifically, the frame FB includes a flow rate detection unit FDU formed in the semiconductor chip CHP1 in an opening OP (FB) formed therein, and the semiconductor chip CHP1 outside the frame FB. A plurality of pads PD1 formed in the above are mounted so as to be arranged. Thus, the frame body FB can be mounted on the semiconductor chip CHP1 while exposing the flow rate detection unit FDU and the plurality of pads PD1.

  At this time, since the frame body FB in the first embodiment has the wall portion WP, the frame body FB is disposed on the semiconductor chip CHP1 while the wall portion WP is in close contact with one side surface of the semiconductor chip CHP1. can do. Thereby, the positioning accuracy of the frame FB mounted on the semiconductor chip CHP1 can be improved, and the flow rate detection unit FDU can be reliably exposed from the opening OP (FB) formed in the frame FB. In addition, the contact between the frame FB and the pad PD1 can be prevented.

  Here, the frame body FB and the semiconductor chip CHP1 may be bonded or may not be bonded. However, from the viewpoint of suppressing the displacement of the frame FB mounted on the semiconductor chip CHP1, it is desirable to bond the frame FB to the semiconductor chip CHP1.

  Thereafter, as shown in FIG. 11, the surface of the semiconductor chip CHP1, the wire W1, the lead LD1, the wire W2, the entire main surface of the semiconductor chip CHP2, the wire W3 and a part of the lead LD2 in the vicinity region where the pad PD1 is formed. Is sealed with resin MR (molding process). Specifically, as shown in FIG. 11, the lead frame LF on which the semiconductor chip CHP1 and the semiconductor chip CHP2 on which the frame body FB is mounted is sandwiched between the upper mold UM and the lower mold BM through the second space. Thereafter, the resin MR is poured into the second space under heating, whereby the surface of the semiconductor chip CHP1, the wires W1, the leads LD1, the wires W2, and the entire main surface of the semiconductor chip CHP2 in the vicinity region where the pad PD1 is formed. The wire W3 and a part of the lead LD2 are sealed with the resin MR. At this time, as shown in FIG. 11, the inner space of the diaphragm DF is separated from the second space described above by the adhesive ADH1, and therefore, when the second space is filled with the resin MR, the diaphragm DF It is possible to prevent the resin MR from entering the internal space.

  Further, in the first embodiment, since the semiconductor chip CHP1 in which the flow rate detection unit FDU is formed can be performed in a state of being fixed by a mold through the frame body FB, the positional deviation of the semiconductor chip CHP1 is suppressed. However, a part of the semiconductor chip CHP1 and the semiconductor chip CHP2 can be sealed with the resin MR. This is because, according to the manufacturing method of the flow sensor FS1 in the first embodiment, a part of the semiconductor chip CHP1 and the entire region of the semiconductor chip CHP2 are sealed with the resin MR while suppressing the displacement of each flow sensor. This means that it is possible to suppress variation in the position of the flow rate detection unit FDU formed in the semiconductor chip CHP1. As a result, according to the first embodiment, the position of the flow rate detection unit FDU that detects the flow rate of gas can be matched by each flow rate sensor, so that variation in performance of detecting the gas flow rate in each flow rate sensor can be suppressed. A remarkable effect can be obtained.

  Here, the manufacturing method of the flow rate sensor FS1 in the present first embodiment is characterized in that the upper mold is placed on the frame FB higher than the height of the flow rate detection unit FDU formed in the semiconductor chip CHP1 via the elastic film LAF. The lead frame LF on which the semiconductor chip CHP1 is mounted is sandwiched between the lower mold BM and the upper mold UM while pressing the UM.

  Thus, according to the first embodiment, the first space SP1 (sealed space) surrounding the flow rate detection unit FDU formed in the semiconductor chip CHP1 and the vicinity thereof is secured, for example, as a pad formation region. The surface region of the semiconductor chip CHP1 can be sealed. That is, according to the first embodiment, the surface region of the semiconductor chip CHP1 typified by the pad formation region is sealed while exposing the flow rate detection unit FDU formed in the semiconductor chip CHP1 and the vicinity thereof. Can do.

  As described above, the essential function of the frame FB is to secure the first space SP1 (sealed space) surrounding the flow rate detection unit FDU and its vicinity when the upper mold UM is pressed against the frame FB. In order to realize this essential function, when the frame body FB is arranged on the semiconductor chip CHP1, the structure in which the height of the frame body FB is higher than the height of the flow rate detection unit FDU is taken. is there. That is, the configuration in which the height of the frame body FB is higher than the height of the flow rate detection unit FDU is to secure the first space SP1 (sealed space) surrounding the flow rate detection unit FDU and its vicinity region from the viewpoint of the manufacturing method. With this configuration, it is possible to seal the surface region of the semiconductor chip CHP1 typified by the pad formation region while exposing the flow rate detection unit FDU and its neighboring region. Furthermore, in the first embodiment, the flow rate detection exposed from the opening OP (FB) of the frame FB is provided on the semiconductor chip CHP1 by providing the frame FB having a height higher than that of the flow rate detection unit FDU. It can also be said that the portion FDU can be protected from the clamping force of the upper mold UM.

  On the other hand, the configuration in which the height of the frame FB is higher than the height of the flow rate detection unit FDU is, from the viewpoint of the structure of the flow rate sensor FS1, the flow rate detection unit FDU in which the components are exposed at the time of mounting and assembly of the components. This can also be regarded as a structure that can prevent the semiconductor chip CHP1 from colliding with the semiconductor chip CHP1. That is, the configuration in which the height of the frame body FB is made higher than the height of the flow rate detection unit FDU can be said to have a remarkable effect from both the viewpoint of the manufacturing method and the viewpoint of the structure.

  Furthermore, the frame body FB in the first embodiment is made of a material whose hardness is softer than that of the semiconductor chip CHP1, and by this configuration, the frame body FB has another function. Hereinafter, another function of the frame FB will be described.

  The feature of the manufacturing method of the flow sensor FS1 in the first embodiment is that when the lead frame LF mounting the semiconductor chip CHP1 is sandwiched between the upper mold UM and the lower mold BM, the lead frame LF mounting the semiconductor chip CHP1 The frame FB and the elastic film LAF are interposed between the upper mold UM.

  For example, since there is a dimensional variation in the thickness of each semiconductor chip CHP1, when the thickness of the semiconductor chip CHP1 is thinner than the average thickness, the lead frame LF on which the semiconductor chip CHP1 is mounted is connected to the upper mold UM. When sandwiched by the lower mold BM, a gap is generated, and the resin MR leaks out of the gap on the flow rate detection unit FDU.

  On the other hand, when the thickness of the semiconductor chip CHP1 is larger than the average thickness, the force applied to the semiconductor chip CHP1 increases when the lead frame LF on which the semiconductor chip CHP1 is mounted is sandwiched between the upper mold UM and the lower mold BM. The semiconductor chip CHP1 may be broken.

  Therefore, in the first embodiment, in order to prevent the resin leakage onto the flow rate detection unit FDU due to the above-described thickness variation of the semiconductor chip CHP1 or the breakage of the semiconductor chip CHP1, the lead on which the semiconductor chip CHP1 is mounted. A device is provided in which an elastic film LAF and a frame body FB are interposed between the frame LF and the upper mold UM. Thereby, for example, when the thickness of the semiconductor chip CHP1 is thinner than the average thickness, a gap is generated when the lead frame LF mounting the semiconductor chip CHP1 is sandwiched between the upper mold UM and the lower mold BM. Since the gap can be filled with the elastic film LAF, resin leakage onto the semiconductor chip CHP1 can be prevented.

  On the other hand, when the thickness of the semiconductor chip CHP1 is larger than the average thickness, the elastic film LAF and the frame body FB are used when the lead frame LF on which the semiconductor chip CHP1 is mounted is sandwiched between the upper mold UM and the lower mold BM. Since it is softer than the semiconductor chip CHP1, the dimensions of the elastic film LAF and the frame body FB in the thickness direction change so as to absorb the thickness of the semiconductor chip CHP1. As a result, even if the thickness of the semiconductor chip CHP1 is larger than the average thickness, it is possible to prevent the semiconductor chip CHP1 from being subjected to an excessive force, and as a result, to prevent the semiconductor chip CHP1 from being broken. Can do.

  That is, according to the manufacturing method of the flow sensor in the first embodiment, the semiconductor chip CHP1 is pressed by the upper mold UM through the elastic film LAF and the frame FB. For this reason, component mounting variations due to thickness variations of the semiconductor chip CHP1, the adhesive ADH1, and the lead frame LF can be absorbed by changes in the thickness of the elastic film LAF and the frame FB.

  In particular, in the first embodiment, the mounting variation in the thickness direction (Z direction) of the component is large, and the mounting variation of the component due to the thickness variation of the semiconductor chip CHP1, the adhesive ADH1, and the lead frame LF is an elastic film. Even when it cannot be absorbed due to a change in the thickness of LAF, the clamping force applied to the semiconductor chip CHP1 is reduced by deformation in the thickness direction (Z direction) of the frame FB having a smaller elastic coefficient than that of the semiconductor chip CHP1. can do. As a result, according to the first embodiment, it is possible to prevent damage represented by cracks, chips, cracks, and the like of the semiconductor chip CHP1.

  Here, it is important that the elastic film LAF and the frame FB have an elastic coefficient smaller than that of the semiconductor chip CHP1 in order to absorb component mounting variations. Thereby, even when there is a variation in the mounting of components, the clamping force from the upper mold UM applied to the semiconductor chip CHP1 is effectively reduced by the change in the thickness of the elastic film LAF and the deformation of the frame FB. Can do. That is, in the first embodiment, the elastic coefficient of the elastic film LAF and the frame FB only needs to be smaller than the elastic coefficient of the semiconductor chip CHP1, and the combination of the elastic coefficients of the elastic film LAF and the frame FB is free. is there. For example, the elastic coefficient of the frame FB may be larger or smaller than the elastic coefficient of the elastic film LAF, or may be the same. As the elastic film LAF, for example, a polymer material such as Teflon (registered trademark) or a fluororesin can be used.

  As described above, another function of the frame body FB in the first embodiment is a function of suppressing an increase in clamping force from the upper mold UM to the semiconductor chip CHP1 due to component mounting variation. And in order to implement | achieve this function, in this Embodiment 1, it is comprised so that the elastic coefficient of frame FB may become smaller than the elastic coefficient of semiconductor chip CHP1. Thereby, even when there is a variation in the mounting of components, the clamping force applied to the semiconductor chip CHP1 is relaxed by deformation in the thickness direction (Z direction) of the frame FB having a smaller elastic coefficient than the semiconductor chip CHP1. be able to. As a result, according to the first embodiment, it is possible to prevent damage represented by cracks, chips or cracks of the semiconductor chip CHP1.

  Subsequently, further features of the first embodiment will be described. As shown in FIG. 11, in the first embodiment, the resin MR also flows into the back side of the lead frame LF. Therefore, since the opening OP1 is formed at the bottom of the chip mounting portion TAB1, there is a concern that the resin MR flows into the inner space of the diaphragm DF from the opening OP1.

  Therefore, in the first embodiment, the shape of the lower mold BM that sandwiches the lead frame LF is devised. Specifically, as shown in FIG. 11, a protruding insertion piece IP1 is formed in the lower mold BM, and is formed in the lower mold BM when the lead frame LF is sandwiched between the upper mold UM and the lower mold BM. The protruding insertion piece IP1 is inserted into an opening OP1 formed at the bottom of the chip mounting portion TAB1. As a result, the insert piece IP1 is inserted into the opening OP1 without a gap, and therefore, the resin MR can be prevented from entering the inner space of the diaphragm DF from the opening OP1. That is, in the first embodiment, a protruding insertion piece IP1 is formed in the lower mold BM, and this insertion piece IP1 is inserted into the opening OP1 formed at the bottom of the chip mounting portion TAB1 during resin sealing. doing.

  Furthermore, in the first embodiment, the shape of the insert piece IP1 is devised. Specifically, in the first embodiment, the insert piece IP1 includes an insertion portion that is inserted into the opening OP1 and a pedestal portion that supports the insertion portion. The cross-sectional area is large. Thus, the insert piece IP1 has a structure in which a step portion is provided between the insertion portion and the pedestal portion, and the step portion is in close contact with the bottom surface of the chip mounting portion TAB1.

  By configuring the insert piece IP1 in this way, the following effects can be obtained. For example, in the case where the shape of the insert piece IP1 is configured only from the insertion portion described above, the insertion portion is inserted into the opening portion OP1, so the diameter of the insertion portion of the insertion piece IP1 is slightly smaller than the diameter of the opening portion OP1. It has become. Therefore, when the insertion piece IP1 is configured only from the insertion portion, even if the insertion portion of the insertion piece IP1 is inserted into the opening OP1, there is a slight gap between the inserted insertion portion and the opening OP1. Conceivable. In this case, the resin MR may enter the inner space of the diaphragm DF from the gap.

  Therefore, in the first embodiment, the insertion piece IP1 is configured to be formed on the pedestal portion having a larger cross-sectional area than the insertion portion. In this case, as shown in FIG. 11, the insertion portion of the insertion piece IP1 is inserted into the opening OP1, and the pedestal portion of the insertion piece IP1 comes into close contact with the bottom surface of the chip mounting portion TAB1. As a result, even if a slight gap is generated between the insertion part of the insertion piece IP1 and the opening OP1, the pedestal part is firmly pressed against the back surface of the chip mounting part TAB1, so that the resin MR enters the opening OP1. It can be prevented. That is, in the first embodiment, the insertion piece IP1 is configured to provide the insertion portion on the pedestal portion having a larger cross-sectional area than the insertion portion, and therefore the resin MR reaches the opening OP1 by the pedestal portion. The combination of the fact that the step portion formed between the pedestal portion and the insertion portion is pressed against the chip mounting portion TAB1 makes the resin MR the internal space of the diaphragm DF through the opening OP1. It is possible to effectively prevent intrusion.

  As described above, in the first embodiment, the lead frame LF on which the semiconductor chip CHP1 and the semiconductor chip CHP2 on which the frame body FB is mounted is connected to the upper mold UM and the lower mold BM via the second space. Sandwich. Thereafter, the resin MR is poured into the second space under heating, whereby the surface of the semiconductor chip CHP1, the wires W1, the leads LD1, the wires W2, and the entire main surface of the semiconductor chip CHP2 in the vicinity region where the pad PD1 is formed. The wire W3 and a part of the lead LD2 are sealed with the resin MR.

  Thereafter, as shown in FIG. 12, when the resin MR is cured, the lead frame LF on which the semiconductor chip CHP1 and the semiconductor chip CHP2 are mounted is removed from the upper mold UM and the lower mold BM. Thereby, the flow sensor FS1 in the first embodiment can be manufactured.

  In the resin sealing process (molding process) in the first embodiment, since the upper mold UM and the lower mold BM having a high temperature of 80 ° C. or higher are used, the heated upper mold UM and the lower mold BM Heat is transferred from the mold BM to the resin MR injected into the second space in a short time. As a result, according to the manufacturing method of the flow sensor FS1 in the first embodiment, the heating / curing time of the resin MR can be shortened.

  For example, as described in the section of the problem to be solved by the invention, when only fixing a gold wire (wire) with a potting resin, the potting resin does not promote curing by heating, so the potting resin The time until curing becomes long, and the problem that the throughput in the manufacturing process of the flow sensor is lowered becomes obvious.

  On the other hand, in the resin sealing step in the first embodiment, as described above, since the heated upper mold UM and the lower mold BM are used, the heated upper mold UM and the lower mold BM are used. Heat conduction from the mold BM to the resin MR can be performed in a short time, and the heating / curing time of the resin MR can be shortened. As a result, according to the first embodiment, the throughput in the manufacturing process of the flow sensor FS1 can be improved.

  In the first embodiment, for example, as shown in FIG. 11, when the lead frame LF mounting the semiconductor chip CHP1 is sandwiched between the upper mold UM and the lower mold BM, the lead frame LF mounting the semiconductor chip CHP1 The example in which the frame FB and the elastic film LAF are interposed between the upper mold UM has been described. However, the technical idea in the first embodiment is not limited to this. For example, as illustrated in FIG. 13, the semiconductor chip CHP <b> 1 is formed by interposing only the frame FB without using the elastic film LAF. The upper mold UM may be pressed against the mounted lead frame LF.

  Even in this case, by configuring the frame body FB so that the elastic coefficient is smaller than the elastic coefficient of the semiconductor chip CHP1, even if there is a variation in the mounting of components, it is more elastic than the semiconductor chip CHP1. The clamping force applied to the semiconductor chip CHP1 can be reduced by the deformation in the thickness direction (Z direction) of the frame body FB having a small coefficient. As a result, according to the first embodiment, it is possible to prevent damage represented by cracks, chips, cracks, and the like of the semiconductor chip CHP1.

<Usefulness of frame>
Next, the usefulness of the frame body FB employed in the flow sensor FS1 in the first embodiment will be described in further detail.

  (1) FIG. 14 is a diagram illustrating an example of a related technique for resin sealing without using the frame body FB. As shown in FIG. 14, in the related art, in order to configure the flow rate detection unit FDU so as not to be resin-sealed, the upper mold UM is provided with a projecting seal portion SL. Then, by surrounding the flow rate detection unit FDU with the seal portion SL, the first space SP1 (sealed space) can be formed so as to surround the flow rate detection unit FDU. That is, in the related art, the flow rate detection unit FDU is not sealed with resin by surrounding the flow rate detection unit FDU with the seal portion SL provided in the upper mold UM.

  In the related art configured as described above, it is necessary to devise a special idea of providing the upper mold UM with a projecting seal portion SL. That is, in order to manufacture the flow sensor that exposes the flow rate detection unit FDU, it is necessary to prepare a special upper mold UM specialized for manufacturing the flow sensor. Therefore, it is necessary to prepare a special upper mold UM having the seal portion SL.

  On the other hand, in the first embodiment, for example, as shown in FIG. 13, the frame body FB is arranged on the semiconductor chip CHP1, and the upper mold UM is pressed so as to be in close contact with the frame body FB. At this time, in the first embodiment, when the frame body FB is arranged on the semiconductor chip CHP1, the structure in which the height of the frame body FB is higher than the height of the flow rate detection unit FDU is employed. That is, by making the height of the frame FB higher than the height of the flow rate detection unit FDU, the first space SP1 (sealed space) surrounding the flow rate detection unit FDU and its vicinity is necessarily secured. Therefore, according to the first embodiment, it is possible to seal the surface region of the semiconductor chip CHP1 typified by the pad formation region while exposing the flow rate detection unit FDU and its vicinity region.

  That is, in the first embodiment, the frame FB is arranged on the semiconductor chip CHP1 so that the flow rate detection unit FDU is included in the opening OP (FB) provided in the frame FB, and The height of the frame FB is set to be higher than the height of the flow rate detection unit FDU. As a result, even in a state where the surface of the upper mold UM in the cavity is flattened, the first space SP1 (sealed space) surrounding the flow rate detection unit FDU can be secured. That is, according to the first embodiment, for example, the first space SP1 (sealed space) that surrounds the flow rate detection unit FDU without special measures of providing the seal portion SL in the upper mold UM as in the related art. ) Can be secured.

  According to the first embodiment, it is not necessary to use the upper mold UM having a special structure, and a general upper mold UM (general-purpose product) for sealing the entire inside of the cavity with resin. This means that the flow rate sensor FS1 exposing the flow rate detection unit FDU can be manufactured using a general upper mold UM that is a general-purpose product. Therefore, according to the first embodiment, there is no need to prepare a special upper die UM for the flow rate sensor, and a flow rate detection can be performed with a general-purpose upper die UM that is widely used. A flow rate sensor in which the part FDU is exposed can be manufactured.

  (2) Next, in the related technique shown in FIG. 14, the seal portion SL formed in the upper mold UM is in direct contact with the semiconductor chip CHP1. Therefore, a clamping force is transmitted from the seal portion SL formed in the upper mold UM to the semiconductor chip CHP1.

  Here, for example, since there is a dimensional variation in the thickness of the individual semiconductor chip CHP1, when the thickness of the semiconductor chip CHP1 is larger than the average thickness, the lead frame LF on which the semiconductor chip CHP1 is mounted is overcoated. When sandwiched between the mold UM and the lower mold BM, the clamping force applied to the semiconductor chip CHP1 from the seal portion SL increases, and the semiconductor chip CHP1 may be broken.

  On the other hand, in the first embodiment, the upper mold UM is not directly pressed against the semiconductor chip CHP1, but the frame FB is interposed between the upper mold UM and the semiconductor chip CHP1. In the first embodiment, a material whose elastic coefficient of the frame FB is smaller than that of the semiconductor chip CHP1 is used. Accordingly, since the frame FB is softer than the semiconductor chip CHP1, when the upper mold UM is pressed against the frame FB, the thickness dimension of the frame FB is absorbed so as to absorb the thickness variation of the semiconductor chip CHP1. Changes. Thereby, even if the thickness of the semiconductor chip CHP1 is larger than the average thickness, it is possible to prevent the clamping force from being applied to the semiconductor chip CHP1 more than necessary. As a result, according to the first embodiment, breakage of the semiconductor chip CHP1 can be prevented.

  (3) Furthermore, in the related technique shown in FIG. 14, the contact area between the seal portion SL formed in the upper mold UM and the semiconductor chip CHP1 is small. For this reason, the clamping force pressed from the upper mold UM concentrates on the contact area between the seal portion SL and the semiconductor chip CHP1. Therefore, the pressure applied to the contact portion between the seal portion SL and the semiconductor chip CHP1 is increased, and the semiconductor chip CHP1 is easily damaged. In particular, in the related technique shown in FIG. 14, the contact region between the seal portion SL and the semiconductor chip CHP1 is formed in a region that overlaps the diaphragm DF in a planar manner. This means that a contact region between the seal portion SL and the semiconductor chip CHP1 exists in a region where the thickness of the semiconductor chip CHP1 is thin. Since the region where the thickness of the semiconductor chip CHP1 is thin is easy to break, in the related technology shown in FIG. 14, the pressure concentration due to the small contact area between the seal portion SL and the semiconductor chip CHP1 and the contact region are the semiconductor chip CHP1. The semiconductor chip CHP1 is likely to be damaged due to being disposed so as to overlap with the thin region in plan view.

  On the other hand, in the first embodiment, for example, as shown in FIG. 13, the contact area between the frame FB and the semiconductor chip CHP1 is larger than that in the related technology shown in FIG. For this reason, the clamping force applied to the frame FB from the upper mold UM is dispersed because the contact area between the frame FB and the semiconductor chip CHP1 is large. Therefore, according to the first embodiment, the local concentration of the clamping force applied to the semiconductor chip CHP1 from the upper mold UM via the frame FB can be reduced, thereby suppressing the breakage of the semiconductor chip CHP1. can do. Furthermore, for example, as shown in FIG. 13, the contact area between the frame FB and the semiconductor chip CHP1 does not overlap with the diaphragm DF in plan view. That is, in the first embodiment, the contact region between the frame FB and the semiconductor chip CHP1 is not formed in the thin region of the semiconductor chip CHP1 in which the diaphragm DF is formed, but other semiconductor chips. It is formed in a thick region of CHP1. As described above, according to the first embodiment, the clamping force is dispersed due to the increase in the contact area between the frame body FB and the semiconductor chip CHP1, and the contact region has the thickness of the semiconductor chip CHP1. The damage of the semiconductor chip CHP1 can be effectively suppressed by the synergistic effect of being formed in the thick region.

  (4) Further, as described above, in the related technology shown in FIG. 14, since the contact area between the seal portion SL and the semiconductor chip CHP1 is small, the injected resin surrounds the flow rate detection portion FDU in the first space SP1 ( There is an increased risk of leaking into a sealed space.

  On the other hand, in the first embodiment, the contact area between the frame FB and the semiconductor chip CHP1 is large, so that the risk of leaking into the first space SP1 (sealed space) surrounding the flow rate detection unit FDU is reduced. be able to.

  As described above, according to the first embodiment, the frame body FB having a height higher than that of the flow rate detection unit FDU and having a smaller elastic coefficient than that of the semiconductor chip CHP1 is used as described above ( The usefulness shown in 1) to (4) can be obtained.

<Modification 1>
Subsequently, Modification 1 of the flow sensor FS1 in the first embodiment will be described. In the first embodiment, for example, as illustrated in FIG. 4, the example in which the frame FB has the wall WP has been described. However, in the first modification, the wall WP is provided in the frame FB. An example that is not described will be described.

  FIG. 15A is a plan view showing the flow sensor FS1 in the first modification. 15B is a cross-sectional view taken along the line AA in FIG. 15A, and FIG. 15C is a cross-sectional view taken along the line BB in FIG. 15A. is there.

  As shown in FIGS. 15B and 15C, the frame portion FB disposed on the semiconductor chip CHP1 has no wall portion. Even when the frame FB having no wall portion is used as described above, the height of the frame FB is higher than the height of the flow rate detection unit FDU, and the elastic coefficient of the frame FB is a semiconductor chip. If it is smaller than CHP1, the same effect as the first embodiment can be obtained.

  However, in the frame FB in the first modification, it is difficult to improve the positioning accuracy due to the wall portion, and therefore the frame in the first modification 1 from the viewpoint of securely fixing the frame FB on the semiconductor chip CHP1. The FB is desirably bonded to the semiconductor chip CHP1. At this time, for the adhesion between the frame body FB and the semiconductor chip CHP1, for example, an adhesive can be used, or the frame body FB may be made of a material having an adhesive action.

  For example, when the outer dimension of the frame FB is larger than the outer dimension of the semiconductor chip CHP1, the position of the frame FB may be shifted due to the resin pressure in the resin sealing process (molding process). Therefore, for example, the outer dimension of the frame FB is desirably smaller than the outer dimension of the semiconductor chip CHP1. In other words, it can be said that the frame FB is desirably formed so as to be included in the semiconductor chip CHP1 in plan view. In other words, it can be said that the frame FB has a smaller outer dimension than the projection surface of the upper surface of the semiconductor chip CHP1. By comprising in this way, the position shift of the frame FB resulting from the resin pressure in a resin sealing process can be suppressed.

  FIG. 16 is a diagram showing a cross section of the flow sensor in the first modification. As shown in FIG. 16, it can be seen that the frame FB is included in the semiconductor chip CHP1. Specifically, in FIG. 16, when the width of the semiconductor chip CHP1 is L1 and the width of the frame body is L2, the frame body FB is the semiconductor chip CHP1 when the relationship of L1> L2 is established in every cross section. It can be said that it is included.

<Modification 2>
Next, a second modification of the flow sensor FS1 in the first embodiment will be described. In the first embodiment, for example, as shown in FIGS. 5B and 5C, the frame body FB is disposed on the semiconductor chip CHP1 mounted on the chip mounting portion TAB1 via the adhesive ADH1. An example was described. In the second modification, an example in which the plate-like structure PLT is inserted between the semiconductor chip CHP1 and the lead frame LF will be described.

  FIG. 17 is a plan view showing the structure of the flow sensor before resin sealing in the second modification. 18 is a cross-sectional view taken along the line AA in FIG. 17, and FIG. 19 is a cross-sectional view taken along the line BB in FIG.

  As shown in FIG. 17, in the flow rate sensor FS1 in the second modification, it can be seen that the plate-like structure PLT is formed over the lower layer of the semiconductor chip CHP1 and the lower layer of the semiconductor chip CHP2. This plate-like structure PLT has, for example, a rectangular shape, and has an external dimension that encloses the semiconductor chip CHP1 and the semiconductor chip CHP2 in plan view.

  Specifically, as shown in FIGS. 18 and 19, the plate-like structure PLT is arranged on the lead frame LF including the chip mounting portion TAB1 and the chip mounting portion TAB2. The plate-like structure PLT is bonded to the lead frame LF using, for example, an adhesive ADH3, but can be bonded using a paste material. On the plate-like structure PLT, a semiconductor chip CHP1 is mounted via an adhesive ADH1, and a semiconductor chip CHP2 is mounted via an adhesive ADH2. At this time, when the plate-like structure PLT is formed of a metal material, it can be connected to the semiconductor chip CHP1 by the wire W1, and can also be connected to the semiconductor chip CHP2 by the wire W2. In addition to the above-described plate-like structure PLT, components such as a capacitor and a thermistor can be mounted on the lead frame LF.

  The plate-like structure PLT described above mainly functions as a cushioning material against an improvement in rigidity of the flow sensor FS1 and an external impact. Further, when the plate-like structure PLT is made of a conductive material, it is electrically connected to the semiconductor chip CHP1 (pad PD1) or the semiconductor chip CHP2 (pad PD2) and used for supplying a ground potential (reference potential). It is also possible to stabilize the ground potential.

  The plate-like structure PLT is, for example, a thermoplastic resin such as PBT resin, ABS resin, PC resin, nylon resin, PS resin, PP resin, or fluorine resin, or thermosetting resin such as epoxy resin, phenol resin, or urethane resin. It can consist of In this case, the plate-like structure PLT can mainly function as a buffer material that protects the semiconductor chip CHP1 and the semiconductor chip CHP2 from external impacts.

  On the other hand, the plate-like structure PLT can be formed by pressing a metal material such as an iron alloy, an aluminum alloy, or a copper alloy, or can be formed from a glass material. In particular, when the plate-like structure PLT is formed from a metal material, the rigidity of the flow sensor FS1 can be increased. Furthermore, the plate-like structure PLT can be electrically connected to the semiconductor chip CHP1 and the semiconductor chip CHP2, and the plate-like structure PLT can be used for supplying the ground potential and stabilizing the ground potential.

  Also in the flow rate sensor FS1 in Modification 2 configured as described above, for example, as illustrated in FIGS. 17 to 19, the frame body FB is disposed on the semiconductor chip CHP1. An opening OP (FB) is formed inside the frame FB, and the flow rate detection unit FDU formed in the semiconductor chip CHP1 is exposed from the opening OP (FB). Also in the second modification, the height of the frame FB is made higher than the height of the flow rate detection unit FDU, and the elastic coefficient of the frame FB is made smaller than that of the semiconductor chip CHP1, so that Similar effects can be obtained.

(Embodiment 2)
In the first embodiment, for example, as shown in FIG. 5B, the flow sensor FS1 having a two-chip structure including the semiconductor chip CHP1 and the semiconductor chip CHP2 has been described as an example. The present invention is not limited to this, and can be applied to a flow sensor having a one-chip structure including one semiconductor chip in which a flow rate detection unit and a control unit (control circuit) are integrally formed. In the second embodiment, a case where the technical idea of the present invention is applied to a flow sensor having a one-chip structure will be described as an example.

<Mounting configuration of flow sensor in embodiment 2>
FIG. 20 is a diagram illustrating a mounting configuration of the flow rate sensor FS2 according to the second embodiment, and is a diagram illustrating a configuration before sealing with resin. In particular, FIG. 20A is a plan view showing a mounting configuration of the flow rate sensor FS2 in the second embodiment. 20B is a cross-sectional view taken along the line AA in FIG. 20A, and FIG. 20C is a cross-sectional view taken along the line BB in FIG. 20A. FIG. 20D is a plan view showing the back surface of the semiconductor chip CHP1.

  First, as shown in FIG. 20A, the flow sensor FS2 according to the second embodiment has a lead frame LF made of, for example, a copper material. This lead frame LF has a chip mounting portion TAB1 inside surrounded by a dam bar DM constituting the outer frame body. The semiconductor chip CHP1 is mounted on the chip mounting portion TAB1.

  The semiconductor chip CHP1 has a rectangular shape, and a flow rate detection unit FDU is formed substantially at the center. A wiring WL1A connected to the flow rate detection unit FDU is formed on the semiconductor chip CHP1, and the wiring WL1A is connected to the control unit CU formed on the semiconductor chip CHP1. In the control unit CU, an integrated circuit made of a semiconductor element such as a MISFET (Metal Insulator Semiconductor Field Effect Transistor) or a wiring is formed. Specifically, an integrated circuit constituting the CPU 1, the input circuit 2, the output circuit 3 or the memory 4 shown in FIG. 1 is formed. The control unit CU is connected to a plurality of pads PD1 and pads PD2 formed along the long side of the semiconductor chip CHP1 by a wiring WL1B. That is, the flow rate detection unit FDU and the control unit CU are connected by the wiring WL1A, and the control unit CU is connected to the pad PD1 and the pad PD2 by the wiring WL1B. The pad PD1 is connected to a lead LD1 formed on the lead frame LF via, for example, a wire W1 made of a gold wire. On the other hand, the pad PD2 is connected to a lead LD2 formed on the lead frame LF via, for example, a wire W2 made of a gold wire. It should be noted that a polyimide film may be formed on the outermost surface (element formation surface) of the semiconductor chip CHP1 for the purpose of a stress buffer function with a resin to be bonded, a surface protection function, an insulation protection function, or the like. To do.

  The lead LD1 and the lead LD2 are arranged so as to extend in the X direction orthogonal to the Y direction in which the gas flows, and have a function of performing input / output with an external circuit. On the other hand, protruding leads PLD are formed along the Y direction of the lead frame LF. The protruding lead PLD is connected to the chip mounting portion TAB1, but is not connected to the pads PD1 and PD2 formed on the semiconductor chip CHP1. That is, the protruding lead PLD is different from the leads LD1 and LD2 that function as the input / output terminals described above.

  Here, in the second embodiment, the semiconductor chip CHP1 is mounted on the chip mounting portion TAB1 so that the long side of the rectangular semiconductor chip CHP1 is parallel to the gas flow direction (arrow direction, Y direction). ing. A plurality of pads PD1 and PD2 are arranged along the long side direction on the long side of the semiconductor chip CHP1. Each of the plurality of pads PD1 and each of the plurality of leads LD1 are connected by a plurality of wires W1 arranged so as to straddle the long side of the semiconductor chip CHP1. Similarly, each of the plurality of pads PD2 and each of the plurality of leads LD2 are connected by a plurality of wires W2 arranged so as to straddle the long side of the semiconductor chip CHP1. As described above, since the plurality of pads PD1 and PD2 are arranged along the long side of the rectangular semiconductor chip CHP1, compared to the case where the plurality of pads PD1 and PD2 are arranged in the short side direction of the semiconductor chip CHP1, Many pads PD1 and PD2 can be formed on the semiconductor chip CHP1. In particular, in the second embodiment, since not only the control unit CU but also the flow rate detection unit FDU is formed on the semiconductor chip CHP1, the semiconductor chip CHP1 is arranged by arranging a large number of pads PD1 and PD2 in the long side direction. The upper area can be used effectively.

  Further, in the second embodiment, the frame body FB is formed on a part of the semiconductor chip CHP1. The frame body FB has, for example, a rectangular shape, and has an opening OP (FB) formed therein. The frame body FB is arranged so that the flow rate detection unit FDU formed on the main surface of the semiconductor chip CHP1 is exposed from the opening OP (FB), and the semiconductor chip CHP1 is disposed outside the frame body FB. The plurality of formed pads PD1 are arranged so as to be exposed.

  Subsequently, as shown in FIG. 20B, a chip mounting portion TAB1 is formed on the lead frame LF, and the semiconductor chip CHP1 is mounted on the chip mounting portion TAB1. The semiconductor chip CHP1 is bonded to the chip mounting portion TAB1 with an adhesive ADH1. A diaphragm DF (thin plate portion) is formed on the back surface of the semiconductor chip CHP1, and a flow rate detection unit FDU is formed on the surface of the semiconductor chip CHP1 facing the diaphragm DF. On the other hand, an opening OP1 is formed at the bottom of the chip mounting portion TAB1 existing below the diaphragm DF.

  Further, as shown in FIG. 20B, in addition to the flow rate detection unit FDU, a pad PD1 and a pad PD2 are formed on the surface (upper surface) of the semiconductor chip CHP1, and the pad PD1 is formed in the lead frame LF. Is connected to the lead LD1 formed on the wire W1. Similarly, the pad PD2 is connected to a lead LD2 formed on the lead frame LF via a wire W2. A frame FB is arranged on the semiconductor chip CHP1. An opening OP (FB) is formed in the frame FB, and the flow rate detection unit FDU is exposed from the opening OP (FB).

  As shown in FIG. 20C, the chip mounting portion TAB1 and the protruding lead PLD are formed on the lead frame LF, and the chip mounting portion TAB1 and the protruding lead PLD are integrally formed. On the chip mounting part TAB1, the semiconductor chip CHP1 is bonded by an adhesive ADH1. A diaphragm DF (thin plate portion) is formed on the back surface of the semiconductor chip CHP1, and a flow rate detection unit FDU is formed on the surface of the semiconductor chip CHP1 facing the diaphragm DF. On the other hand, an opening OP1 is formed at the bottom of the chip mounting portion TAB1 existing below the diaphragm DF. In addition, a control unit CU is formed on the surface of the semiconductor chip CHP1 so as to be aligned with the flow rate detection unit FDU. Similarly, the frame body FB is disposed on the semiconductor chip CHP1. An opening OP (FB) is formed in the frame FB, and the flow rate detection unit FDU is exposed from the opening OP (FB).

  As the adhesive ADH1 for bonding the semiconductor chip CHP1 and the chip mounting portion TAB1, for example, a thermosetting resin such as an epoxy resin or a polyurethane resin, or a thermoplastic resin such as a polyimide resin or an acrylic resin can be used.

  For example, the semiconductor chip CHP1 and the chip mounting portion TAB1 can be bonded by applying an adhesive ADH1 as shown in FIG. FIG. 20D is a plan view showing the back surface of the semiconductor chip CHP1. As shown in FIG. 20D, a diaphragm DF is formed on the back surface of the semiconductor chip CHP1, and an adhesive ADH1 is applied so as to surround the diaphragm DF. FIG. 20C shows an example in which the adhesive ADH1 is applied so as to surround the diaphragm DF in a square shape. However, the present invention is not limited to this. For example, the diaphragm DF is surrounded by an arbitrary shape such as an elliptical shape. As described above, the adhesive ADH1 may be applied.

  In the flow rate sensor FS2 in the second embodiment, the mounting configuration of the flow rate sensor FS2 before sealing with resin is configured as described above, and the mounting configuration of the flow rate sensor FS2 after sealing with resin is described below. Will be described.

  FIG. 21 is a diagram illustrating a mounting configuration of the flow rate sensor FS2 according to the second embodiment, and is a diagram illustrating a configuration after sealing with a resin. In particular, FIG. 21A is a plan view showing a mounting configuration of the flow sensor FS2 in the second embodiment. 21B is a cross-sectional view taken along line AA in FIG. 21A, and FIG. 21C is a cross-sectional view taken along line BB in FIG.

  Also in the flow rate sensor FS2 in the second embodiment, as shown in FIG. 21A, the flow rate detection unit FDU formed in the semiconductor chip CHP1 is exposed from the opening OP (FB) formed in the frame body FB. In this state, a part of the semiconductor chip CHP1 is covered with the resin MR. That is, in the second embodiment, the region of the semiconductor chip CHP1 excluding the region where the flow rate detection unit FDU is formed and the region where the frame body FB is mounted is collectively sealed with the resin MR.

  The sealing with the resin MR can be performed in a state in which the semiconductor chip CHP1 in which the flow rate detection unit FDU is formed is fixed by a mold, and therefore, the semiconductor chip CHP1 can be prevented from being displaced and one of the semiconductor chips CHP1 is suppressed. The portion can be sealed with the resin MR. This means that according to the flow rate sensor FS2 in the second embodiment, a part of the semiconductor chip CHP1 can be sealed with the resin MR while suppressing the positional deviation of each flow rate sensor FS2, and the semiconductor chip CHP1 is attached to the semiconductor chip CHP1. It means that the variation in the position of the formed flow rate detection unit FDU can be suppressed.

  As a result, according to the second embodiment, the position of the flow rate detection unit FDU that detects the flow rate of gas can be matched by each flow rate sensor FS2, so that there is performance variation in detecting the gas flow rate in each flow rate sensor FS2. The remarkable effect which can be suppressed can be acquired.

  Subsequently, also in the flow rate sensor FS2 in the second embodiment, as shown in FIG. 21A, the height of the frame FB on both sides surrounding the exposed flow rate detection unit FDU, or the resin MR (sealing) The height of the (stopper) is higher than the height of the surface of the semiconductor chip CHP1 including the flow rate detection unit FDU. That is, the exposed flow rate detection unit FDU is surrounded by the frame FB, and the height of the frame FB surrounding the flow rate detection unit FDU is higher than the height of the flow rate detection unit FDU. According to the second embodiment configured as described above, it is possible to prevent the parts from being exposed to the flow rate detection unit FDU where the parts are exposed at the time of mounting and assembling the parts, so that the semiconductor chip in which the flow rate detection unit FDU is formed Damage to CHP1 can be prevented. In other words, the height of the frame FB surrounding the flow rate detection unit FDU is higher than the height of the exposed flow rate detection unit FDU. For this reason, when the component contacts, first, since it contacts the frame body FB having a high height, the exposed surface (XY surface) of the semiconductor chip CHP1 including the low flow rate detection unit FDU contacts the component, It is possible to prevent the semiconductor chip CHP1 from being damaged.

  In particular, in the second embodiment, the frame FB is disposed on a part of the semiconductor chip CHP1, and the elastic coefficient of the frame FB is smaller than the elastic coefficient of the semiconductor chip CHP1. In other words, the frame FB is made of a softer material than the semiconductor chip CHP1. Therefore, when the component comes into contact with the frame FB, the shock can be absorbed by the deformation of the relatively soft frame FB. Therefore, the impact is applied to the semiconductor chip CHP1 disposed under the frame FB. It is possible to suppress the transmission, and thereby it is possible to effectively prevent the semiconductor chip CHP1 from being damaged.

  Also in the second embodiment, in order to prevent the resin MR from entering the inner space of the diaphragm DF, for example, the adhesive ADH1 is applied so as to surround the diaphragm DF formed on the back surface of the semiconductor chip CHP1. It is premised on taking the composition to do. Then, as shown in FIGS. 21B and 21C, an opening OP1 is formed at the bottom of the chip mounting portion TAB1 below the diaphragm DF formed on the back surface of the semiconductor chip CHP1, and further, the chip An opening OP2 is provided in the resin MR that covers the back surface of the mounting portion TAB1.

  Thereby, according to the flow rate sensor FS2 according to the second embodiment, the internal space of the diaphragm DF flows through the opening OP1 formed in the bottom of the chip mounting portion TAB1 and the opening OP2 formed in the resin MR. It communicates with the external space of the sensor FS2. As a result, the pressure in the inner space of the diaphragm DF and the pressure in the outer space of the flow rate sensor FS2 can be equalized, and stress can be suppressed from being applied to the diaphragm DF.

  As described above, the flow sensor FS2 according to the second embodiment is mounted and configured. In the actual flow sensor FS2, the dam bar DM that configures the outer frame of the lead frame LF after sealing with the resin MR. Is removed. FIG. 22 is a plan view showing a mounting configuration of the flow rate sensor FS2 after the dam bar DM is removed. As shown in FIG. 22, it can be seen that by cutting the dam bar DM, a plurality of electric signals can be taken out independently from the plurality of leads LD1 and leads LD2.

<Method for Manufacturing Flow Rate Sensor in Second Embodiment>
The flow sensor FS2 in the second embodiment is configured as described above, and the manufacturing method thereof will be described below with reference to FIGS. 23 to 26 show the manufacturing process in the cross section cut along the line BB in FIG.

  First, as shown in FIG. 23, for example, a lead frame LF made of a copper material is prepared. The lead frame LF is integrally formed with a chip mounting portion TAB1 and a protruding lead PLD, and an opening OP1 is formed at the bottom of the chip mounting portion TAB1.

  Subsequently, as shown in FIG. 24, the semiconductor chip CHP1 is mounted on the chip mounting portion TAB1. Specifically, the semiconductor chip CHP1 is connected to the chip mounting portion TAB1 formed on the lead frame LF with an adhesive ADH1. At this time, the semiconductor chip CHP1 is mounted on the chip mounting portion TAB1 so that the diaphragm DF formed on the semiconductor chip CHP1 communicates with the opening OP1 formed at the bottom of the chip mounting portion TAB1. The semiconductor chip CHP1 is formed with a flow rate detection unit FDU, a control unit CU, wiring (not shown), and pads (not shown) by a normal semiconductor manufacturing process. And the diaphragm DF is formed in the position of the back surface facing the flow volume detection part FDU formed in the surface of the semiconductor chip CHP1 by anisotropic etching, for example.

  Next, pads (not shown) formed on the semiconductor chip CHP1 and leads (not shown) formed on the lead frame LF are connected by wires (not shown) (wire bonding). A wire (not shown) is formed from a gold wire, for example.

  Thereafter, the frame body FB is mounted on the semiconductor chip CHP1. Specifically, the frame FB includes a flow rate detection unit FDU formed in the semiconductor chip CHP1 in an opening OP (FB) formed therein, and the semiconductor chip CHP1 outside the frame FB. It is mounted so that the control unit CU formed in is arranged. Accordingly, the frame body FB can be mounted on the semiconductor chip CHP1 while exposing the flow rate detection unit FDU and the control unit CU.

  Next, as shown in FIG. 25, with respect to the lead frame LF on which the semiconductor chip CHP1 on which the frame body FB is mounted, the second space (in the upper mold UM and the lower mold BM with the elastic film LAF interposed) Cavity) is formed and sandwiched. Thereafter, the resin MR is poured into the second space under heating, whereby the surface of the semiconductor chip CHP1, the wire (not shown), and a part of the protruding lead PLD in the vicinity region where the control unit CU is formed are resinated. Seal with MR.

  Also in the manufacturing method of the flow rate sensor FS2 in the second embodiment as described above, for example, as shown in FIG. 25, the elastic film is applied to the frame body FB higher than the height of the flow rate detection unit FDU formed in the semiconductor chip CHP1. While pressing the upper mold UM through the LAF, the lead frame LF on which the semiconductor chip CHP1 is mounted is sandwiched between the lower mold BM and the upper mold UM.

  Thereby, according to the second embodiment, the first space SP1 (sealed space) surrounding the flow rate detection unit FDU formed in the semiconductor chip CHP1 and the vicinity thereof is secured, for example, as a control unit formation region. The surface region of the semiconductor chip CHP1 to be manufactured can be sealed. That is, according to the second embodiment, the surface region of the semiconductor chip CHP1 typified by the control unit formation region is sealed while exposing the flow rate detection unit FDU formed in the semiconductor chip CHP1 and its neighboring region. be able to.

  Further, also in the manufacturing method of the flow sensor FS2 in the second embodiment, when the lead frame LF mounted with the semiconductor chip CHP1 is sandwiched between the upper mold UM and the lower mold BM, the lead frame LF mounted with the semiconductor chip CHP1. A frame body FB and an elastic film LAF are interposed between the upper mold UM and the upper mold UM.

  Thereby, even when there is a variation in the mounting of components, the clamping force applied to the semiconductor chip CHP1 is relaxed by deformation in the thickness direction (Z direction) of the frame FB having a smaller elastic coefficient than the semiconductor chip CHP1. be able to. As a result, according to the second embodiment, it is possible to prevent damage represented by cracks, chips, cracks, and the like of the semiconductor chip CHP1.

  Thereafter, as shown in FIG. 26, at the stage where the resin MR is cured, the lead frame LF on which the semiconductor chip CHP1 is mounted is removed from the upper mold UM and the lower mold BM. Thereby, the flow sensor FS2 in the second embodiment can be manufactured. The flow sensor FS2 according to the second embodiment manufactured as described above can achieve the same effects as those of the first embodiment.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

In the flow sensor described in the above embodiment, a polyimide film, a silicon nitride film, a polysilicon film, TEOS (Si (OC ₂ H ₅ ) A film such as a silicon oxide film using ₄ ) as a raw material may be formed. Thereby, it is possible to improve the adhesive strength in a part of the surface of the semiconductor chip CHP1 that is in close contact with the resin.

  For example, the polyimide film can be formed by coating on the semiconductor chip CHP1 and patterned by applying a photolithography technique and an etching technique as necessary. The silicon nitride film, polysilicon film, and silicon oxide film are formed by chemical vapor deposition, chemical vapor deposition, chemical vapor deposition, physical vapor deposition represented by plasma CVD, low pressure CVD, and atmospheric pressure CVD. It can be formed by the method or physical vapor deposition.

  These films formed on the semiconductor chip CHP1 prevent an increase in the thickness of the silicon oxide film formed on the silicon (Si) constituting the semiconductor chip CHP1, thereby improving the adhesion between the resin MR and the semiconductor chip CHP1. Can be improved.

  These films may be formed on at least a part of the semiconductor chip CHP1 covered with the resin MR.

  In addition, the film thickness of a polyimide film, a silicon nitride film, a polysilicon film, a silicon oxide film using TEOS as a raw material is assumed to be about 1 μm to about 120 μm, but is not limited to this film thickness. It is only necessary that these films be formed in the region covered with the resin MR in the surface region of the semiconductor chip CHP1.

The flow sensor described in the above-described embodiment is a device that measures the flow rate of gas, but the specific type of gas is not limited, and air, LP gas, carbon dioxide gas (CO ₂ gas), The present invention can be widely applied to devices that measure the flow rate of any gas such as Freon gas.

  In the above-described embodiment, the flow sensor for measuring the flow rate of gas has been described. However, the technical idea of the present invention is not limited to this, and a part of a semiconductor element such as a humidity sensor is exposed. The present invention can be widely applied to semiconductor devices that are resin-sealed in such a state.

  The present invention can be widely used, for example, in the manufacturing industry for manufacturing semiconductor devices such as flow sensors.

1 CPU
2 Input circuit 3 Output circuit 4 Memory ADH1 Adhesive ADH2 Adhesive ADH3 Adhesive BM Lower mold BR1 Downstream RTD BR2 Downstream RTD CHP1 Semiconductor chip CHP2 Semiconductor chip CU Controller DF Diaphragm DM Dam bar FD Frame FD Flow detection part FP Frame part FS1 Flow sensor FS2 Flow sensor HCB Heater control bridge HR Heating resistor IP1 Insertion piece LAF Elastic film LD1 Lead LD2 Lead LF Lead frame MR Resin OP1 Opening OP2 Opening OP (FB) Opening PD1 Pad PD2 pad PD3 pad PLD protruding lead PLT plate structure PS power supply Q gas flow rate R1 resistor R2 resistor R3 resistor R4 resistor SL seal part SP1 first space TAB1 chip mounting part TAB2 Flop mounting portion Tr transistor TSB temperature sensor bridge UM upper mold UR1 upstream resistance temperature detector UR2 upstream resistance temperature detector Vref1 reference voltage Vref2 reference voltage W1 wire W2 wire W3 wire WL1 wiring WL1A wiring WL1B wiring WP wall

Claims (14)

The first semiconductor chip having the flow rate detection part formed in the thin part is a flow rate sensor arranged in the first chip mounting part,
A frame body mounted on the first semiconductor chip and having an opening exposing at least the flow rate detection unit;
In a state where the flow rate detection part formed in the first semiconductor chip is exposed from the opening of the frame body, a part of the first semiconductor chip is sealed with a sealing body containing resin,
The frame body having the opening has a wall portion that is parallel to at least one side surface of the first semiconductor chip and closely contacts the side surface,
The flow sensor which is arrange | positioned so that the frame part and the said thin part which comprise the said frame may not overlap in planar view. The flow sensor according to claim 1,
The first semiconductor chip further includes a control circuit unit that controls the flow rate detection unit. The flow sensor according to claim 1,
further,
A second chip mounting portion;
A second semiconductor chip disposed on the second chip mounting portion,
It said second semiconductor chip has the system that controls the flow rate detecting unit control circuit portion,
The flow rate sensor in which the second semiconductor chip is sealed with the sealing body. The flow sensor according to claim 1,
The frame body having the opening and the first semiconductor chip are bonded to each other. The flow sensor according to claim 1,
The frame body having the opening and the first semiconductor chip are not bonded to each other. The flow sensor according to claim 1,
A flow sensor in which a polyimide film, a silicon nitride film, a polysilicon film, or a silicon oxide film is formed on at least a part of the first semiconductor chip. The flow sensor according to claim 1,
The flow rate sensor in which the height of the frame or the sealing body is higher than the height of the first semiconductor chip including the flow rate detection unit in an arbitrary cross section including the exposed flow rate detection unit. The flow sensor according to claim 1,
A flow sensor in which a plate-like structure is inserted between the first chip mounting portion and the first semiconductor chip. The flow sensor according to claim 1,
The frame body is a flow sensor made of a material having an elastic coefficient smaller than that of the first semiconductor chip. The flow sensor according to claim 1,
When the frame is mounted on the first semiconductor chip, the flow sensor has a height that is higher than the height of the flow rate detector. A first semiconductor chip having a flow rate detection unit formed in the thin part and disposed in the first chip mounting unit;
A frame mounted on the first semiconductor chip and having an opening exposing at least the flow rate detection unit;
Including
In a state where the flow rate detection part formed in the first semiconductor chip is exposed from the opening of the frame body, a part of the first semiconductor chip is sealed with a sealing body containing resin,
The frame having the opening has a wall portion parallel to at least one side surface of the first semiconductor chip,
In a plan view, the frame portion constituting the frame body and the thin portion are a manufacturing method of a flow sensor arranged so as not to overlap,
(A) preparing a base material having the first chip mounting portion;
(B) preparing the first semiconductor chip;
(C) mounting the first semiconductor chip on the first chip mounting portion;
(D) After the step (c), the flow rate detection unit is included in the opening formed in the frame, and the wall is in close contact with at least one side surface of the first semiconductor chip, And the step of arranging the frame on the first semiconductor chip so that the frame portion constituting the frame and the thin portion do not overlap,
(E) After the step (d), the step of sealing a part of the first semiconductor chip with the sealing body while exposing the flow rate detection part formed in the first semiconductor chip. Prepared,
The step (e)
(E1) preparing an upper mold and a lower mold;
(E2) After the step (e1), the upper mold and the lower mold are formed while forming a first space surrounding the flow rate detection unit by bringing the bottom surface of the upper mold into close contact with the frame. And sandwiching the substrate on which the first semiconductor chip is mounted via a second space;
(E3) A method of manufacturing a flow sensor comprising: a step of pouring the resin into the second space after the step (e2). It is a manufacturing method of the flow sensor according to claim 11,
The flow rate sensor manufacturing method, wherein the first semiconductor chip further includes a control circuit unit that controls the flow rate detection unit. The method for manufacturing a flow sensor according to claim 11, further comprising:
(F) comprising a step of preparing a second semiconductor chip having a control circuit unit for controlling the flow rate detection unit before the step (c);
The base material prepared in the step (a) has a second chip mounting portion,
In the step (c), the second semiconductor chip is mounted on the second chip mounting portion,
In the step (e), the second semiconductor chip is sealed with the sealing body,
In the step (e2), the upper mold and the lower mold are used to form the first space surrounding the flow rate detection unit by bringing the bottom surface of the upper mold into close contact with the frame. A method for manufacturing a flow sensor, wherein the base material on which the first semiconductor chip and the second semiconductor chip are mounted is sandwiched through the second space. It is a manufacturing method of the flow sensor according to claim 11,
The step (e2) is a method for manufacturing a flow sensor in which the upper mold is brought into close contact with the frame body through an elastic film.

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