JP6129980B2 - Mechanical quantity measuring apparatus and manufacturing method thereof - Google Patents

Description

  The present invention relates to a mounting structure of a mechanical quantity measuring device and a manufacturing method thereof.

  As a method for measuring the deformation (strain) of a measurement object, a technique using a metal foil strain gauge utilizing the fact that the resistance value of the metal foil changes due to strain is known. By attaching this strain gauge to the object to be measured, the length of the metal foil is changed following the strain of the object to be measured, and the resistance value of the metal foil that changes as a result can be detected to enable strain measurement of the object to be measured. Technology. Up to now, there are strain gauges using Cu-Ni alloy foils and Ni-Cr alloy foils, etc. In addition to ensuring and stabilizing the strain gauge attachment (sticking), it is also moisture and impact resistant. High protector strain gauges have also been proposed.

  However, since these have high power consumption, there is a problem that the battery is consumed quickly. In order to reduce power consumption, a semiconductor strain gauge in which a strain sensitive resistor is formed on silicon has been proposed.

  As a structure for attaching this semiconductor strain gauge to an object to be measured instead of a strain gauge using a conventional metal thin film, a flexible thin film provided with a plurality of electrodes and a semiconductor substrate on which a plurality of electric elements are formed The flexible thin film is attached to the semiconductor substrate, and the plurality of electrodes and the plurality of electrical elements are electrically connected to each other. A structure is proposed in Patent Document 1.

  Further, Patent Document 2 has a strain detection element formed of a silicon chip and a pedestal that transmits strain to be detected to the strain detection element. The pedestal has a thermal expansion coefficient of ± 50% of the thermal expansion coefficient of silicon. A strain detection sensor is disclosed in which a silicon chip formed of a material that falls within the range, a glass-based fixing material heated and melted, and a strain detection element formed on the pedestal is fixed.

JP 2001-264188 A JP 2001-272287 A

  As a semiconductor strain gauge, accuracy and sensitivity for correctly transmitting strain generated in a measurement object to a strain detection unit of a semiconductor chip (hereinafter referred to as a sensor chip) are important. In addition, when the same amount of distortion occurs in the object to be measured for a long time, the stability of the sensor output value indicating the same detection value is important in the sensor chip. These requirements become a difficult problem when the object to be measured is used at a high temperature. In addition to general household items, applications for measuring mechanical quantities such as strain and pressure can be used for controlling the operation of automobile devices and monitoring important infrastructures, for example. In this case, it is necessary to assume the usage environment up to a temperature range of about 150 ° C. at high temperatures.

  Usually, the main material of the sensor chip is silicon, and it is bonded to the object to be measured using a bonding material such as solder. This bonding needs to be performed at a temperature lower than the heat resistance temperature of the sensor chip. As a general solder, Sn-3 wt% Ag-0.5 wt% Cu solder having a melting point near 217 ° C., Pb-5 wt% Sn solder having a melting point of about 310 ° C., and the like are known. With Sn-3wt% Ag-0.5wt% Cu solder, the temperature is close to the melting point in the operating environment near 100 ° C to 150 ° C, and the yield stress of the solder becomes small and softens. Under conditions where the strain continues to be applied, deformation such as creep of the bonding layer occurs, and fluctuation in sensor output becomes a problem. Pb-5wt% Sn solder containing a large amount of lead has a higher melting point than Sn-based solder, but it is a soft material, so there are still concerns about sensitivity drop and fluctuations in sensor output value.

  Therefore, in order to ensure the normal operation of the sensor at a high temperature, it is conceivable to bond the sensor chip and the object to be measured using a hard bonding material having a very high melting point. The temperature cannot be exceeded. Further, when bonding at a high temperature, the silicon chip may be cracked at the time of bonding due to the difference in thermal expansion coefficient between the sensor chip and the object to be measured, and there is a concern that the manufacturing yield may be reduced.

  Since the organic thin film is used in Patent Document 1 filed so far, use at high temperatures is predicted to be difficult. Further, Patent Document 2 shows a structure in which a glass-based fixing material is used by being heated and melted, and can be expected to be a hard material. It is considered necessary.

  As described above, in the semiconductor strain gauge mounting structure, the performance of the sensor, such as sensitivity and sensor output stability, is greatly affected by the structure of the joint between the sensor chip and the object to be measured. For this reason, in this invention, the junction part of the sensor chip which has a distortion | strain detection part in a semiconductor substrate, and a to-be-measured object is optimized, and the distortion which generate | occur | produced in the to-be-measured object is detected with high sensitivity and correctly also at high temperature. It is an object of the present invention to provide a sensor chip bonding structure (including a sensor chip and its bonding portion structure, hereinafter referred to as a mechanical quantity measuring device in the present invention), and a manufacturing method thereof.

  It is another object of the present invention to provide a sensor chip bonding structure that can be manufactured at a high yield, and a method for manufacturing the same, which prevents a chip crack failure when bonding the sensor chip and the measurement object.

The present application includes a plurality of means for solving the above problems.
In the manufacturing method of the mechanical quantity measuring device, an initial metallized layer including a material that forms a solid solution with Au and forms a solid solution strengthening is formed on a base substrate, and at least 50 wt% or more of Au is included on the initial metallized layer. A sensor chip in which a solder is stacked, a sensor chip in which a strain detection portion is formed on a semiconductor substrate is mounted on the solder with the back surface thereof facing, and the stacked body is placed in a heating furnace, so that the heat resistance of the sensor chip is increased. A bonding layer is formed by heating at a temperature below the solder melting temperature or higher and melting part or all of the material for solid solution strengthening of Au in the solder from the initial metallized layer in contact with the solder into the solder. I did it. Furthermore, a wiring board for drawing out wiring from the electrode of the sensor chip to the outside is attached and configured.

  Further, in order to solve the above problems, in the present invention, instead of the base substrate, a material that forms a solid solution with Au on the surface of a member constituting a mechanically measured object and includes a material that solidifies and strengthens Au is included. An initial metallization layer is formed, a solder containing at least 50 wt% or more of Au is laminated on the initial metallization layer of the member, and a sensor chip having a strain detection portion formed on a semiconductor substrate is formed on the solder, and a back surface thereof is formed. The laminated body is placed in the heating furnace, heated to a temperature lower than the heat resistance temperature of the sensor chip and higher than a solder melting temperature, and Au in the solder is fixed from the initial metallized layer in contact with the solder. A part or all of the material to be melt strengthened is dissolved in solder to form a bonding layer on the surface of the member constituting the object to be measured, and the sensor chip and the member constituting the object to be measured are directly bonded. How to Subjected to. Further, the present invention provides a method for manufacturing a mechanical quantity measuring device, characterized in that a wiring board for drawing wiring from the electrode of the sensor chip to the outside is attached.

  In order to solve the above problems, in the present invention, a mechanical quantity measuring device is interposed between a sensor chip in which a strain detection unit is formed on a semiconductor substrate, and an object to be measured and the sensor chip. And a base substrate that transmits the strain of the measurement object to be detected to the sensor chip, and a wiring portion that draws wiring from the electrode of the sensor chip to the outside, the base substrate, the sensor chip, In between, at least 50 wt% or more of Au is contained before heating, and by heating in the heating furnace, a solid solution containing Au and the material is formed by melting a material that solidifies and strengthens Au from the metallized layer to be connected. The base substrate and the sensor chip each having a bonding layer made of solder and a metallized layer having the remaining material dissolved into the solder layer to which the material is connected. It comprised so that it might join.

  In order to solve the above problems, in the present invention, in the mechanical quantity measuring device, instead of the base substrate, a member constituting an object to be measured of the mechanical quantity is provided, and between the member and the sensor chip. Has a laminated metallized layer and a bonding layer, and the sensor chip is directly bonded to the member.

  According to the present invention, it is possible to detect a strain generated in an object to be measured with high sensitivity even at a high temperature, and to achieve a stable and accurate sensor output even when strain is applied for a long period of time. A high-performance mechanical quantity measuring device and a manufacturing process thereof can be provided.

  Further, it is possible to provide a mechanical quantity measuring device capable of reducing chip cracking failure at the time of joining the sensor chip and the object to be measured, and capable of being manufactured at a high yield, and a manufacturing process thereof.

It is an example of the cross-sectional block diagram of the mechanical quantity measuring apparatus of Example 1 of this invention. It is an example of the plane block diagram of the mechanical quantity measuring apparatus of Example 1 of this invention. It is a figure explaining the process which joins a sensor chip and a base substrate in a heating furnace in the manufacturing method of the mechanical quantity measuring device of Example 1 of this invention. In the manufacturing method of the mechanical quantity measuring apparatus of Example 1 of this invention, it is a figure explaining the mode of a joining layer when all the initial metallization layers 7 melt | dissolved in the solder containing Au. In the manufacturing method of the mechanical quantity measuring apparatus of Example 1 of this invention, it is a figure explaining the mode of a joining layer when a part of initial stage metallization layer 7 melt | dissolves in the solder material 8 containing Au. In the manufacturing method of the mechanical quantity measuring apparatus of Example 1 of this invention, it is a figure explaining a mode that the melt | dissolution of the initial metallization layer 7 to the solder material 8 containing Au is not uniform. It is sectional drawing of the example which joined the mechanical quantity measuring apparatus of Example 1 of this invention, and the to-be-measured object. In the mechanical quantity measuring apparatus of Example 1 of the present invention, the results of verifying the effect of preventing chip cracking at the time of joining and improving the creep resistance at high temperature by using a combination of various metallized layers and solder. It is a summarized table. It is a figure explaining the process which joins a sensor chip and a base substrate within a heating furnace in the manufacturing method of the mechanical quantity measuring device of Example 2 of this invention. It is an example of the cross-sectional block diagram of the mechanical quantity measuring apparatus of Example 2 of this invention. It is a figure explaining the process which joins a sensor chip and a base substrate in a heating furnace in the manufacturing method of the mechanical quantity measuring device of Example 3 of this invention. It is an example of the cross-sectional block diagram of the mechanical quantity measuring apparatus of Example 3 of this invention. In the manufacturing method of the mechanical quantity measuring device of Example 4 of this invention, it is a figure explaining the process which joins a sensor chip and a base substrate within a heating furnace. It is an example of the cross-sectional block diagram of the mechanical quantity measuring apparatus of Example 4 of this invention. It is sectional drawing of the pressure sensor module 500 of Example 5 of this invention. It is sectional drawing of the pressure sensor module 600 which concerns on the modification of Example 5 of this invention. In the mechanical quantity measuring apparatus of Example 1 of this invention, it is an example of the cross-sectional block diagram in which the eutectic of Si and Au forms the fillet 23 in a part of side surface of the sensor chip 1, or the whole side surface.

  Embodiments of the present invention will be described below with reference to the drawings. However, in the following description, the same components may be denoted by the same reference numerals and repeated description may be omitted. In order to clarify the description, the drawings may be schematically represented with respect to the width, thickness, shape, etc. of each part as compared to the actual embodiment, but are merely examples, and the interpretation of the present invention is not limited to them. It is not limited. Needless to say, the present invention is not limited to the following examples and can be variously modified.

  In this embodiment, an example of the structure of a sensor chip, a base substrate, and a joint portion thereof, which are components of the mechanical quantity measuring device, will be described. When a mechanical quantity measuring device is provided as a product, the base substrate is mounted when the user attaches (attaches / connects) the mechanical quantity measuring device to the object to be measured and measures the distortion generated in the object to be measured. This is a connection element for facilitating connection to the object to be measured. A configuration method of a mechanical quantity measuring apparatus that directly joins a sensor chip to a member constituting a measurement target without using a base substrate will be described in the following embodiments.

  1 and 2 are diagrams showing examples of a cross-sectional structure and a planar structure of the mechanical quantity measuring device 100 of the present embodiment. The sensor chip 1 has a strain detection portion 2 on the main surface 1a, and the sensor chip back surface 1b, which is the surface opposite to the main surface 1a of the sensor chip 1, has a bonding layer 3, a metallized layer 5, and an intermediate metallized layer 6 interposed therebetween. And connected to the base substrate 4. The strain detector 2 is provided near the center of the sensor chip, and a Wheatstone bridge circuit composed of four impurity diffusion resistors is formed. As a result, the strain is detected by the resistance value of the impurity diffusion resistor changing due to the expansion and contraction generated in the plane direction of the sensor chip 1. The sensor chip 1 is provided with a part for measuring temperature as required. If the temperature can be measured at the same time, the temperature of the measured value can be corrected, and a more accurate strain amount can be measured. In this example, the sensor chip 1 is disposed at substantially the center of the base substrate 4, but there is no problem even if it is not particularly the center.

A printed circuit board 20 is disposed on the base substrate 4, and the electrode pads 21 on the printed circuit board 20 and the electrode pads 29 of the sensor chip 1 are connected by bonding wires 22 using Au wire or the like. The printed board 20 may be a board using a glass epoxy material, a flexible board using a polyimide material, or a ceramic board. Further, wiring may be created in the base substrate 4 in accordance with a method for producing a metal base substrate, and the base substrate 4 and the printed circuit board 20 may be combined into one.
A metallized layer 5 is disposed on the base substrate 4 at the mounting position of the sensor chip 1, and the bonding layer 3 between the metallized layer 5 and the sensor chip 1 is a solder layer containing Au, and Si, Ge, Ni, Sn, It is configured to include one or more elements of In and Sb and one or more elements of Cu, Ag, Co, Pt, Cr, Fe, and Pd. The metallized layer 5 on the base substrate 4 contains one or more elements of Cu, Ag, Co, Pt, Cr, Fe, and Pd. An intermediate metallized layer 6 such as Ni may be provided between the base substrate 4 and the metallized layer 5 in order to improve the adhesion of the metallized layer 5.

  The metallized layer is generally used in such a manner that it is sandwiched between the solder layer and the material to be joined in order to improve the wettability between the solder layer and the material to be joined and improve the adhesion. In an embodiment of the present invention, the metallized layer contains an element that dissolves into the solder layer and forms a solid solution with Au contained in the solder layer or an intermetallic compound to modify the Au phase, and joins the element. It also has a role of supplying to the department.

FIG. 3 is a diagram illustrating a process for joining the sensor chip 1 and the base substrate 4 in the heating furnace 10 in the method for manufacturing the mechanical quantity measuring device 100. That is, an intermediate metallized layer 6 and an initial metallized layer 7 are disposed on the base substrate 4, a solder material 8 containing Au is mounted on the initial metallized layer 7, and then a main part having a strain detecting portion 2 of the sensor chip 1. The surface 1 b opposite to the surface 1 a is mounted so as to contact the solder material 8. On the back surface 1 b of the sensor chip 1, Ti, Ni, Au layer, Ti, Pt, Au layer, Ti, Pt, Ag layer, Ti, Ni as an initial metallization layer 9 in order to improve the bondability with the solder material 8. The Ag layer is applied by plating or vapor deposition. These are put in the heating furnace 10 and heated by, for example, a heater 11 or the like.
As the heating and temperature rise, the solder material 8 containing Au melts and is bonded to the initial metallization layer 9 on the back surface 1 b of the sensor chip 1 and the initial metallization layer 7 of the base substrate 4. At this time, the initial metallization layer 7 of the base substrate 4 includes one or more elements of Cu, Ag, Co, Pt, Cr, Fe, and Pd. Then, some or all of the components of the initial metallization layer are dissolved in the solder material 8 containing Au from the initial metallization layer 7 of the base substrate 4.

  On the other hand, at the interface of the sensor chip 1, the surface Au, Ag layer, etc. of the initial metallized layer 9 are generally thin and melt into the solder material 8 containing Au during connection, and the Ni layer (shown) Not).

  FIG. 4 shows the state of the bonding layer when the entire initial metallized layer 7 is dissolved in the solder containing Au. When all of the initial metallized layer 7 is dissolved in the solder material 8 containing Au, the intermediate metallized layer 6 and the solder come into contact with each other, and a part of the intermediate metallized layer 6 may be dissolved in the solder. An intermetallic compound layer 13 is formed at the interface. An intermetallic compound layer 14 is formed between the surface of the sensor chip 1 and the initial metallized layer 9. The intermediate bonding layer 15 has a composition in which the initial metallized layer 7 is dissolved in Au.

  FIG. 5 shows a state of the bonding layer when a part of the initial metallized layer 7 is dissolved in the solder material 8 containing Au. Since a part of the initial metallized layer 7 is melted, a part of the initial metallized layer 7 remains on the intermediate metallized layer 6, and the intermetallic compound layer 13 is formed adjacent thereto. Further, an intermetallic compound layer 14 is also formed between the surface of the sensor chip 1 and the initial metallized layer 9. The intermediate bonding layer 17 has a composition in which the components of the initial metallized layer 7 are dissolved in Au. The initial metallization layer 7 is not uniformly melted into the solder material 8 containing Au, and as shown in FIG. 6, the melt around the chip is faster than the central part of the chip, and the initial metallization layer 7 near the center remains thick. There are many cases. Thus, only the lower part of the center part of the chip becomes the thick metallized layer 7, and the ratio of solder in the bonding layer 17 is small and the reliability is improved.

  As described above, in the bonding layer 3 or the bonding layers 15 and 17 between the sensor chip 1 and the base substrate 4 after cooling, generally soft Au is solid-solution strengthened by the dissolution of the components of the initial metallized layer 7. The For this reason, values such as hardness, tensile strength, and Young's modulus are increased, and the hard bonding layers 3, 15, and 17 can be formed. As described above, since the bonding layers 3, 15, and 17 are hard layers, it is possible to transmit a change in mechanical quantity generated in the base substrate 4 to the strain detection unit 2 on the surface of the sensor chip 1 with high sensitivity. In addition, even in a long period, creep deformation in the bonding layer 3 is reduced, and the sensor output is stabilized.

  For example, when Ag is used for the initial metallized layer 7, Ag melts into the solder material 8 containing Au at the time of bonding, and is dissolved in Au. Au and Ag are in a solid solution relationship, and the dissolution rate is fast, so there is no problem in manufacturing. Accordingly, the Au of the bonding layers 3, 15, and 17 after cooling is different from the Au of the initial solder material 8 in that Ag is a solid solution, and the soft Au is modified by the solid solution strengthening and the strengthening layer Will be formed. In addition, the melting point of the bonding layers 3, 15, and 17 can be increased by the dissolution of Ag, so that the amount of creep deformation of the solder at a high temperature can be reduced. Therefore, the joint structure is capable of high-sensitivity and long-term stable sensor measurement.

  In addition, when Cu is used for the initial metallized layer 7, Cu is dissolved in the solder material 8 containing Au at the time of bonding, and is dissolved in Au. Therefore, the Au of the bonding layers 3, 15, and 17 after cooling becomes a solid solution of Cu, unlike the Au of the initial solder material 8, and soft Au is modified by solid solution strengthening to form a strengthened layer. The Rukoto. In addition, in the case of Au and Cu, a regular lattice of AuCu is formed depending on the Cu content, which has the effect of greatly strengthening soft Au. In this case, it is effective to add a process that promotes regular lattice formation by baking at a high temperature for a long time after joining. In addition, the melting point of the bonding layer is increased by the dissolution of Cu in Au, the amount of creep deformation of the solder at a high temperature is reduced, and a high-sensitivity and long-term stable sensor measurement can be achieved. .

In addition, when a Pt, Ni, Co, Cr, Fe, Pd layer is used for the initial metallization layer 7, each component of the initial metallization layer 7 is dissolved in the solder material 8 containing Au at the time of bonding. It becomes possible to form a reinforcing layer by modifying soft Au. As a result, the amount of creep deformation of the solder at a high temperature is reduced, and a high-sensitivity and stable sensor measurement can be performed for a long period of time.
It is important to optimize the heating conditions because the rate of penetration into the solder material 8 containing Au varies depending on the components of the initial metallization layer 7. However, after joining, baking is performed again at a high temperature to promote diffusion. This process is also effective.

Here, by controlling the atmosphere inside the heating furnace 10, surface oxidation of the solder material 8 containing Au can be suppressed and good bonding can be obtained. For example, N ₂ or the like is effective as the atmosphere, but in addition to this, reducing hydrogen, a mixture thereof, or an organic acid such as formic acid may be used. In addition, an organic substance such as a flux capable of reducing the surface oxide may be used. In order to achieve parallelism of the sensor chip 1, securing a desired bonding height, preventing displacement, and reducing voids in the bonding layer, a bonding correction jig 12 such as a weight 16 or a guide may be used. It is also effective to reduce the voids by vacuuming the periphery of these joining members. By performing such a device, it is possible to obtain good bonding layers 3, 15, and 17 with few defects such as voids. In order to further improve the bondability, it is effective to remove or reduce the amount of organic contamination, oxide film, etc. of the bonding member by performing sputtering treatment before bonding, plasma cleaning, or the like.

  Further, not only a heating furnace but also a so-called die bonder device can be used. The solder material 8 containing Au is supplied onto the initial metallized layer 7 of the base substrate 4, while the sensor chip 1 is vacuum-adsorbed with a collet or the like, and the sensor chip 1 is pressed onto the solder material 8. At this time, it is also possible to heat the collet in a pulsed manner (pulse heat) or constantly (constant heat) to melt the solder material 8 containing Au and join the sensor chip 1 and the base substrate 4 together. . If the base substrate is heated in advance, the bonding time can be further shortened. Even during this die bond bonding, if the vicinity of the bonding portion is kept in an inert atmosphere, better bonding becomes possible. After bonding by die bonding, it is possible to transfer to another apparatus such as a high-temperature bath and reheat to increase the amount of the metallized layer 7 component dissolved in the bonding layer 17.

  As the material of the base substrate 4, Al, Al alloy, Cu, Cu alloy, SUS, 42 alloy, Mo, CIC, or the like can be used.

  As a solder material containing Au, Au and Ge, Au and Si, Au and In, Au and Sn, Au and Sb binary solder, or Ge, Si, In, Sn, Ni, Sb, Ti, Cu, A solder composed of two or more types of Ag and the remainder composed of Au is suitable. The Au composition is desirably 50 wt% or more.

  For example, in the binary solder containing Au and Si, the melting point is lowered to the eutectic temperature of about 363 ° C. by adding about 3.15 wt% Si as compared with Au having a melting point of 1063 ° C. It is possible to join at a temperature of about 370 to 450 ° C., which is lower than the heat resistance of the steel. However, by bonding to the initial metallization layer 7 having the above structure, the metallization component is dissolved in Au, the melting point of the bonding layers 3, 15, and 17 is increased, and the bonding layer is strengthened by the solid solution strengthening and creep. Resistance is improved. From the beginning, it is conceivable that bonding is performed using a bonding material having a high melting point and containing a melting component containing Au, Si, and an initial metallization layer, but the heat resistance of the sensor chip 1 and the chip during bonding are considered. Considering the occurrence of cracks, there are many manufacturing problems. Therefore, by first using AuSi eutectic containing 3.15 wt% Si in Au, or using a solder material having a low melting point in the vicinity thereof, chip crack occurrence probability is reduced and bonding is performed reliably. A process for improving the strength by modifying the soft Au phase using the penetration of the Au reinforcing component from the metallized layer is effective.

  Similarly, in the binary solder containing Au and Ge, the melting point is lowered to about 356 ° C. of the eutectic temperature by adding about 12 wt% Ge as compared with Au having a melting point of 1063 ° C. Bonding is possible at a temperature of about 370 to 450 ° C., which is lower than heat resistance. However, by bonding to the initial metallization layer 7 having the above structure, the metallization component is dissolved in Au, the melting point of the bonding layers 3, 15, and 17 is increased, and the bonding layer is strengthened by the solid solution strengthening and creep. Resistance is improved. Although it is conceivable to use such a high melting point and high strength bonding material containing Au, Ge, and an insoluble component from the initial metallization layer from the beginning, it is conceivable that the sensor chip has heat resistance, Considering chip cracking, there are many manufacturing problems. Therefore, bonding is first performed by reducing the probability of chip cracking by bonding using AuGe eutectic containing 12wt% Ge in Au or a material having a low melting point in the vicinity thereof, and at the same time, metallizing. A process of improving the strength by modifying the soft Au phase using the penetration of the Au strengthening component from the layer is effective.

  In addition, in the AuSn, AuIn, AuNi, and AuSb systems, the composition having the lowest melting point and the composition in the vicinity thereof are used to reduce the probability of chip cracking by bonding below the heat resistant temperature of the chip. A process of improving the strength by modifying the soft Au phase using the penetration of the Au reinforcing component from the metallized layer 7 is effective.

  Alternatively, the melting point of the solder material can be adjusted by using a solder material that contains two or more of Ge, Si, In, Sn, Ni, Sb, Ti, Cu, and Ag, and the remainder is made of Au. Therefore, high yield bonding can be performed in accordance with the heat resistance and chip cracking strength of the sensor chip. For example, in the case of a solder material containing Ge and Si in Au, the melting point is lowered to 350 ° C. or less depending on the composition, so that it is possible to reduce the incidence of chip crack failure during bonding.

In addition, by using a solder material having a low melting point as much as possible, it is possible to reduce power during production and to reduce the environmental load.
FIG. 7 shows a configuration diagram when measuring the strain amount of the device under test 30 using the mechanical quantity measuring apparatus 100 of the present invention. In this configuration, the base substrate 4 and the DUT 30 are fixed at several locations by welding 31. Thereby, the amount of strain generated in the object to be measured 30 is first transmitted to the base substrate 4, and then transmitted to the strain detection unit 2 of the sensor chip 1 with high sensitivity via the bonding layer 3 with improved sensitivity and creep resistance. It becomes possible to accurately measure the amount of distortion. Here, the base substrate 4 and the object to be measured are fixed by welding 31, but may be fixed by screwing, an adhesive, caulking, a method using heat due to friction, or the like.

  Although not shown, the surface including the surface of the sensor chip 1 and the bonding wire 22 is covered with an insulating material or the like in order to protect the surface of the sensor chip 1 of the mechanical quantity measuring apparatus 100 or the bonding wire 22. May be. Alternatively, it may be possible to cover the whole with a cap or the like.

Next, the shape of the mechanical quantity measuring apparatus 100 of the present embodiment will be described. For example, the sensor chip 1 is approximately 1 mm to 5 mm square, the thickness is 50 to 400 μm, and the thickness of the bonding layer 3 is approximately 200 μm at the maximum. The base substrate 4 has a thickness of about 0.1 to 3 mm. However, when the base substrate 4 is directly bonded to the object to be measured without using the base substrate, even a thicker substrate is not a problem. Moreover, the solder material 8 containing Au is a size suitable for the size of each chip, and a solder pellet having a thickness of about 20 to 200 μm is used. However, other than this, a disk-shaped solder pellet, a ball-shaped solder, a linear solder, or a solder paste in which solder particles are mixed with an organic substance may be used.
Further, the thickness of the initial metallized layer having a component that can be strengthened by modifying soft Au is, for example, about 100 μm at maximum, depending on the modification effect of the component.

As an example, an example using a binary solder of Au and Si is shown. The base substrate 4 was made of SUS420, the thickness was 1 mm, Ni was applied as the intermediate metallized layer 6, and Cu was applied as the initial metallized layer 5. The thickness of each layer varies depending on manufacturing, but the intermediate metallized layer made of Ni was 3 μm, and the initial metallized layer made of Cu was 10 μm. These metallized layers were formed on the entire base substrate 4 by plating. As the solder material 8 containing Au, a binary material of Au-3.15 wt% Si was used, and a solder pellet having a shape substantially the same as the chip and a thickness of 30 μm was prepared. The sensor chip 1 is 3 mm square, and Ti / Ni / Au is applied to the surface 1 b opposite to the strain detection unit 2. Next, the base substrate 4, Au-3.15 wt% Si solder pellets, and sensor chip 1 were sequentially laminated, heated at a maximum temperature of 400 ° C. for about 3 minutes in a reflow furnace in an N ₂ atmosphere, and then cooled. . In this example, since Cu is used as a component that can be modified and strengthened by soft Au, Cu is dissolved in Au in the bonding layer 3, and the amount of penetration varies depending on the location. Almost 30 to 70 at% of Cu was dissolved. These are further subjected to additional high-temperature baking to increase the regular lattice of AuCu, thereby increasing hardness and improving creep resistance at high temperatures. When the shape of the chip changes, the stress generated at the end of the chip due to the difference in thermal expansion coefficient with the base substrate changes, so that the chip crack resistance changes and the creep resistance also changes. Therefore, when the chip shape is about 4 to 5 mm square, the optimum solubility of Cu is also changed, and the creep resistance is good even when Cu is dissolved at about 10 to 50 at% with respect to Au.

  An example of the result of the same examination as described above is shown in the table of FIG. 8. By using a combination of these metallized layers and solder, chip cracking at the time of joining is prevented and creep resistance at high temperature is improved. To do. In FIG. 8, “◯” is indicated when the bondability is good, “◯” is indicated when the creep property (creep resistance) is good, and “「 ”is indicated when the creep property is very good.

  Here, the region where the intermediate metallization layer 6 and the initial metallization layer 7 are formed on the base substrate 4 may be formed entirely, or the metallization layer may be formed only in the vicinity where the sensor chip 1 is mounted. . In this case, partial plating using a resist or the like is performed. Alternatively, the intermediate metallized layer 6 may be applied to the entire base substrate 4, and then the initial metallized layer 7 may be applied only to a portion where the sensor chip 1 is mounted by masking with a resist or the like. Also, if the material of the base substrate 4 is a material such as SUS that has a stable surface and poor adhesion to the plating and is likely to be peeled off, the metallized layer with a small area may be worried about characteristic deterioration due to peeling. However, it is possible to reduce plating peeling defects by setting the intermediate metallized layer 6 as large as possible.

Another effect of modifying such an Au-based solder is the concern with brittle materials because Au is very soft, but mainly modified by the effect of solid solution strengthening. This is effective when there is little problem of impact resistance, especially when reliability for vibration and impact is important, such as in automobile applications. In addition, it has high resistance at low temperatures and is excellent in reliability such as temperature cycle.
Further, since Si and Au, which are the main materials of the sensor chip 1, cause a eutectic reaction, by optimizing the temperature and atmosphere, a part of the side surface of the sensor chip 1 or the side surface as shown in FIG. It is also possible to form the fillet 23 as a whole, and the creep resistance is improved.

In the present embodiment, an example of another manufacturing method and structure of a mechanical quantity measuring device using a sensor chip and a base substrate that are components of the mechanical quantity measuring device will be described.
In the mechanical quantity measuring apparatus 200 of the present embodiment, the sensor chip 1 is the same as that of the first embodiment, but the initial metallized layer containing a component that can be strengthened by modifying the soft Au of the solder material 8 containing Au. 41 is formed on the back surface 1 b of the sensor chip 1.

  FIG. 9 is a diagram showing a method for manufacturing the mechanical quantity measuring device 200. The sensor chip 1 and the base substrate 4 are joined in the heating furnace 10, and a normal metallized layer 42 is formed on the base substrate 4. The solder material 8 containing Au is mounted on the metallized layer 42, and then the initial metallized layer 41 formed on the surface 1 b opposite to the main surface 1 a on which the strain detecting portion 2 of the sensor chip 1 is provided is the solder material 8. Mounted to touch. Thereafter, by heating, the components of the initial metallization layer 41 formed on the back surface 1b of the sensor chip 1 are dissolved in the solder material 8 containing Au, and the joining structure of the mechanical quantity measuring device 200 shown in FIG. 10 is formed. . The bonding layer 43 in this example is made of solder that is modified and strengthened by soft Au. The material of the initial metallization layer 41 is the same as that of the initial metallization layer 7 of the first embodiment. The solder material 8 is the same as that in the first embodiment. Specifically, a part or all of the initial metallized layer 41 on the back surface 1b of the sensor chip 1 is melted into the solder 8 containing Au, and although not shown, an intermetallic compound layer or the like is formed at the interface. . In this way, by adopting such a material and structure for the initial metallized layer 41 on the back surface 1b of the sensor chip 1, it is possible to improve creep resistance at high temperature and to measure the mechanical quantity change of the measurement object with high sensitivity. It becomes possible. In addition, the probability of chip cracking during joining can be reduced.

In the present embodiment, an example of another manufacturing method and structure of a mechanical quantity measuring device using a sensor chip and a base substrate that are components of the mechanical quantity measuring device will be described.
In the mechanical quantity measuring apparatus 300 of the present embodiment, the sensor chip 1 is the same as that of the first embodiment, but the initial metallized layer containing a component that can be strengthened by modifying the soft Au of the solder material 8 containing Au. Is formed on both the back surface 1 b of the sensor chip 1 and the base substrate 4.

  FIG. 11 is a diagram illustrating a method for manufacturing the mechanical quantity measuring apparatus 300. The sensor chip 1 and the base substrate 4 are joined in the heating furnace 10, and an initial metallized layer 44 including a component capable of strengthening soft Au is formed on the base substrate 4. A solder material 8 containing Au is mounted on the metallized layer 44, and then the surface 1 b opposite to the main surface 1 a where the strain detection portion 2 of the sensor chip 1 is in contact with the solder material 8. At this time, an initial metallized layer 45 containing a component capable of reinforcing soft Au is formed on the back surface 1b of the sensor chip 1 in the same manner. Here, an intermediate metallized layer 6 may be formed between the base substrate 4 and the initial metallized layer 44 for the purpose of improving adhesion.

Thereafter, by heating them, a solder material in which the components of the initial metallization layer 45 formed on the back surface 1b of the sensor chip 1 and the components of the initial metallization layer 44 formed on the surface of the base substrate 4 contain Au. 8 is formed to form the joint structure of the mechanical quantity measuring apparatus 300 shown in FIG. The bonding layer 46 in this example is made of solder which is reinforced by modifying soft Au. Specifically, a part or all of the initial metallization layer 45 on the back surface 1b of the sensor chip 1 and the initial metallization layer 44 of the base substrate 4 is melted into the solder 8 containing Au. An intermetallic compound layer or the like is formed. In this way, the initial metallization layer 45 on the back surface 1b of the sensor chip 1 and the initial metallization layer 44 of the base substrate are made of such materials and structures, thereby improving the creep resistance at high temperatures and improving the sensitivity of the object to be measured. It becomes possible to measure the mechanical quantity change. In addition, the probability of chip cracking during joining can be reduced.
In the example of Example 3, the initial metallization layer 45 of the sensor chip 1 and the initial metallization layer 44 on the surface of the base substrate 4 may be the same component, or different components may be used. The materials of the initial metallization layer 44 and the initial metallization layer 45 are the same as those of the initial metallization layer 7 of the first embodiment. The solder material 8 is the same as that in the first embodiment.

In the present embodiment, an example of another manufacturing method and structure of a mechanical quantity measuring device using a sensor chip and a base substrate that are components of the mechanical quantity measuring device will be described.
In Example 3, the initial metallized layers 44 and 45 containing a component capable of strengthening soft Au are formed on both the base substrate 4 and the back surface 1b of the sensor chip 1 to further dissolve into the solder material 8. An example of improving efficiency quickly was shown. In order to realize further rapid melting into the solder material 8, it is considered effective to sandwich an initial metallized layer between the solder materials 8.
In the mechanical quantity measuring apparatus 400 of the present embodiment, the sensor chip 1 is the same as that of the first embodiment, but the initial metallized layer containing a component that can be strengthened by modifying the soft Au of the solder material 8 containing Au. Is formed in three places on the back surface 1b of the sensor chip 1 and the base substrate 4 between the solder material 8 containing Au.

  FIG. 13 is a diagram illustrating a method for manufacturing the mechanical quantity measuring device 400. The sensor chip 1 and the base substrate 4 are joined in the heating furnace 10, and an initial metallized layer 47 containing a component capable of strengthening soft Au is formed on the base substrate 4. A solder material 8 containing Au is mounted on the metallized layer 47, a sheet-like Au modified material 49 and a solder material 8 containing Au are mounted on the metallized layer 47, and then there is a strain detecting portion 2 of the sensor chip 1. The surface 1 b opposite to the main surface 1 a is mounted so as to contact the solder material 8. At this time, an initial metallized layer 48 including a component capable of reinforcing soft Au is formed on the back surface 1b of the sensor chip 1 in the same manner. Here, an intermediate metallized layer 6 may be formed between the base substrate 4 and the initial metallized layer 47 for the purpose of improving adhesion.

Thereafter, these are heated to form a component of the initial metallization layer 48 formed on the back surface 1 b of the sensor chip 1, a component of the Au modified material 49 sandwiched between the solder materials 8, and the surface of the base substrate 4. The components of the initial metallized layer 47 that have been melted relatively quickly into the solder material 8 containing Au, and the joining structure of the mechanical quantity measuring device 400 shown in FIG. 14 is formed. The joining layers 61 and 62 in this example are made of solder which is reinforced by modifying soft Au. Specifically, the initial metallization layer 48 on the back surface 1 b of the sensor chip 1, the Au modified material 49 sandwiched between the solder materials 8, and a solder in which part or all of the initial metallization layer 47 on the base substrate 4 contains Au. Although not shown in the drawing, the intermetallic compound layer and the like are formed at the interface. In this way, by adopting such material and structure, the initial metallization layer 48 on the back surface 1b of the sensor chip 1, the Au modified material 49 sandwiched between the solder materials 8, and the initial metallization layer 47 on the base substrate are adopted. It is possible to improve creep resistance at high temperature and measure the mechanical quantity change of the measurement object with high sensitivity. In addition, the probability of chip cracking during joining can be reduced.
In the example of Example 4, the initial metallized layer 48 of the sensor chip 1, the Au modified material 49 sandwiched between the solder materials 8, and the initial metallized layer 47 on the surface of the base substrate 4 may be the same component, Ingredients may be used. The materials of the initial metallization layer 48, the Au modifying material 49, and the initial metallization layer 47 are the same as those of the initial metallization layer 7 of the first embodiment. The solder material 8 is the same as that in the first embodiment.

  Further, in this embodiment, either or both of the initial metallized layers 47 and 48 formed on the base substrate 4 or the back surface 1b of the sensor chip 1 are omitted, and the Au modification is performed only between the solder materials 8. A configuration in which the bonding material is formed by sandwiching the material 49 is also conceivable.

An example in which the mechanical quantity measuring device of the present invention is applied to a pressure sensor module is shown in FIG.
A pressure sensor module 500 whose sectional view is shown in FIG. 15 has a container 54 including a cylindrical portion 52 provided with a hollow hole 51 inside and a lid portion 53 for closing the upper portion of the hollow hole 51 in the cylindrical portion 52. . In addition, a region of a diaphragm 56 is formed in the lid portion 53 at the upper portion of the hollow hole 51, and the sensor module 57 in which the sensor chip 1 is attached to the base substrate 4 via the bonding layer 3 is the hollow hole 51 in the diaphragm 56 portion. It is attached to the opposite side. Further, in order to output a strain detection amount from the sensor chip 1, a wiring board 20 is attached via a bonding wire 22. Further, a case 58 and a connector (not shown) are attached around the sensor module (mechanical quantity measuring device) 57 for protecting the sensor module 57 and outputting the measurement value.

  The base substrate 4 is made of, for example, a CIC substrate, Mo, 42 Alloy, SUS, Al, ceramic, or the like, and a SUS material or the like is applied to the cylindrical portion 52, the diaphragm 56 portion, or the like. The case 58 is made of resin or the like, but may be made of a metal material if it does not have heat resistance.

  The diaphragm 56 and the base substrate 4 are joined using welding, brazing material, screw fixing, caulking, heat due to friction, or the like. Further, when the volume of the pressure sensor module 500 is limited and cannot be stored, the printed board 20 uses a flexible board or a springy thing such as a connector or a probe pin to extract a signal. It is also possible.

  In the pressure sensor module 500, a joint portion 55 is connected to, for example, a hydraulic piping of an automobile. Therefore, the sensor chip 1 connected to the base substrate 4 bonded on the diaphragm 56 through the bonding layer described in the first to fourth embodiments of the present invention is distorted through the diaphragm 56 according to the change in hydraulic pressure. Convert pressure changes into electrical signals.

  In manufacturing the pressure sensor module 500, a sensor module (mechanical quantity measuring device) 57 in which the sensor chip 1 is attached to the base substrate 4 via the bonding layer 3 may be separately prepared and then attached to the lid portion 53. The process of attaching the sensor chip 1 after attaching the base substrate 4 to the lid portion 53 first may be used.

  A pressure sensor module 600 structure in which the sensor chip 1 is directly joined to the diaphragm 56 (measurement target) without using the base substrate 4 is also possible. This example (modification) is shown in FIG. 16, and the sensor chip 1 is directly bonded to the diaphragm 56 using the bonding layer described in the first to fourth embodiments of the present invention, and the diaphragm 56 is distorted according to the change of the hydraulic pressure. By detecting this amount of strain by the strain detector 2 of the sensor chip 1, the change in pressure is converted into an electrical signal. When the base substrate 4 is not used as in this example, a metallized layer containing a component that can be strengthened by reforming soft Au dissolved in Au on the surface opposite to the hollow hole 51 of the diaphragm 56. Must be applied in advance. Alternatively, when a metallized layer containing a component that can be strengthened by modifying solid Au dissolved in Au is formed on the back surface 1 b of the sensor chip 1, the surface on which the solder can be secured on the diaphragm 56. Only the treatment layer may be formed.

  It is also possible to change the pressure measurement range by forming a thin portion locally on the back side of the diaphragm 56 where the sensor chip 1 is mounted and changing the thickness of the portion.

  In the pressure sensor modules 500 and 600 created in this way, even when the joint part 3 of the sensor chip 1 is high temperature, the creep deformation is small and stable, and the reliability such as the temperature cycle is high. For example, the pressure change when used in a high-temperature environment can be measured with high sensitivity and stably for a long period of time. Also, in the joining process of the sensor chip 1, there are few chip cracking defects and the yield is good.

DESCRIPTION OF SYMBOLS 1 Sensor chip 1a Main surface 1b of sensor chip 2 Back surface of sensor chip 2 Strain detector 3 Bonding layer 4 Base substrate 5 Metallized layer 6 Intermediate metallized layer 7 Initial metallized layer 8 Solder material containing Au 9 Initial metallized layer 10 Heating furnace 11 Heater 12 Bonding correction jig 13 Intermetallic compound layer 14 Intermetallic compound layer 15 Bonding layer 16 in which the initial metallized layer is completely melted Weight 17 Bonding layer 20 in which a part of the initial metallized layer is melted 20 Printed circuit board 21 Printed circuit board electrode 22 Bonding wire 23 Fillet 29 Sensor chip wire bonding electrode 30 DUT 31 Welded portion 41 Initial metallization layer 42 on the back side of the sensor chip 42 Initial metallization layer 43 on the base substrate surface Bonding layer 44 Initial metallization layer 45 on the base substrate surface Metallization layer 46 on the back side of the sensor chip Bonding layer 47 Initial metallization layer 48 on the surface of the base substrate 48 Metallization layer 49 on the back surface of the sensor chip 49 Au modified material 51 Hollow hole 52 Cylindrical part 53 Lid part 54 Container 55 Joint part 56 Diaphragm 57 Sensor module 58 Case 61, 62 Bonding layer 100 Mechanical quantity measurement Apparatus 200 mechanical quantity measuring apparatus 300 mechanical quantity measuring apparatus 400 mechanical quantity measuring apparatus 500 pressure sensor module 600 pressure sensor module

Claims (15)

An initial metallization layer containing a material that forms a solid solution with Au and solidifies and strengthens Au is formed on the base substrate or on the surface of the member constituting the object to be measured of a mechanical quantity ,
Laminating a solder containing at least 50 wt% Au on the initial metallization layer,
On the solder, a sensor chip in which a strain detection part is formed on a semiconductor substrate is mounted with its back surface facing,
A laminate including the metallized layer, the solder, and the sensor chip is placed in a heating furnace, and is heated to a temperature not higher than the heat resistance temperature of the sensor chip and not lower than a solder melting temperature.
A method for manufacturing a mechanical quantity measuring device, wherein a bonding layer is formed by dissolving a part or all of the material for solid solution strengthening of Au in solder from the initial metallized layer in contact with the solder into the solder. In claim 1,
On the back surface opposite to the main surface on which the strain detection portion of the sensor chip is formed, the same material as the material that solidifies and strengthens Au contained in the initial metallization layer, or a material that strengthens and dissolves different types of Au. Forming an initial metallization layer containing,
A method for manufacturing a mechanical quantity measuring device, wherein a back surface on which an initial metallized layer of the sensor chip is formed is laminated and mounted on the solder. In claim 1,
The base substrate or the member constituting the object to be measured of the mechanical quantity, and laminated in two layers of solder containing at least 50 wt% or more of Au sandwich was laminated between the sensor chip,
A method of manufacturing a mechanical quantity measuring apparatus, wherein a bonding layer is formed by sandwiching an Au modified material between solders divided into two layers. The base substrate or on the surface of the part material that make up the object to be measured of a physical quantity, form a metallized layer to ensure only wetting I,
Laminating two layers of solder containing at least 50 wt% or more Au sandwiched between the metallized layer and the sensor chip;
A method of manufacturing a mechanical quantity measuring apparatus, wherein a bonding layer is formed by sandwiching an Au modified material between solders divided into two layers . In any one of claims 1 to 4 ,
The manufacturing method of the mechanical quantity measuring apparatus using the initial metallization layer containing at least any one element of Cu, Ag, Co, Pt, Cr, Fe, or Pd as a material which can carry out the solid solution strengthening of Au in the said solder. In any one of claims 1 to 4 ,
The method of manufacturing a mechanical quantity measuring device, wherein the solder containing Au is a binary solder of Au and Ge, Au and Si, Au and In, Au and Sn, Au and Sb, and Au and Ni. Oite to claim 1 or 2,
The solder containing Au is a mechanical quantity measuring device in which the solder containing Ge, Si, In, Sn, Ni, Sb, Ti, Cu, and Ag contains at least two kinds of elements and the rest is made of Au. Manufacturing method. A sensor chip having a strain detection part formed on a semiconductor substrate;
A base substrate that is interposed between the measurement object and the sensor chip and supports the sensor chip and transmits the distortion of the measurement object to be detected to the sensor chip or a measurement object of a mechanical quantity A member to be
A wiring portion for drawing wiring from the electrode of the sensor chip to the outside;
With
Between the sensor chip and the member constituting the base substrate or the measurement object of the mechanical quantity ,
A metallized layer including a material that forms a solid solution with Au and that strengthens the solid solution of Au, and has the remaining material that has melted into the solder layer to which the material is connected by heating in a heating furnace;
Before heating, the solder contains at least 50 wt% or more, and by heating in the heating furnace, accepts the penetration of the material that solidifies and strengthens Au from the metallized layer to be connected, and forms a solid solution containing Au and the material. A bonding layer comprising:
Having
A mechanical quantity measuring apparatus in which a member constituting the base substrate or the mechanical quantity to be measured is joined to the sensor chip. In claim 8 ,
Between the base substrate and the sensor chip, the metallized layer and the bonding layer are laminated on the base substrate,
A mechanical quantity measuring device in which a second metallized layer is laminated or omitted between the bonding layer and the sensor chip, and the base substrate and the sensor chip are bonded. In claim 8 ,
The bonding layer is divided into a first bonding layer and a second bonding layer between the base substrate and the sensor chip, and a third Au modifying material is provided between the first bonding layer and the second bonding layer. Are stacked,
The first metallized layer between the base substrate and the first bonding layer, and the second metallized layer between the second bonding layer and the sensor chip are laminated or omitted, respectively. A mechanical quantity measuring device in which the base substrate and the sensor chip are joined. In claim 8 ,
Between the member constituting the mechanical measurement object and the sensor chip, the metallized layer and the bonding layer are laminated on the member,
A mechanical quantity measuring apparatus in which a second metallized layer is laminated or omitted between the bonding layer and the sensor chip, and the member and the sensor chip are bonded. In claim 8 ,
The bonding layer is divided into a first bonding layer and a second bonding layer between a member constituting the object to be measured of the mechanical quantity and the sensor chip, and between the first and second bonding layers. Au modified material is laminated to
The first metallized layer between the member and the first bonding layer, and the second metallized layer between the second bonding layer and the sensor chip are respectively laminated or omitted. The mechanical quantity measuring device in which the member and the sensor chip are joined. In any of claims 8 to 1 2,
A mechanical quantity measuring device using a metallized layer containing at least one element of Cu, Ag, Co, Pt, Cr, Fe, or Pd as a material capable of solid solution strengthening of Au in the solder. In any of claims 8 to 1 2,
The solder containing Au is a mechanical quantity measuring device which is a binary solder of Au and Ge, Au and Si, Au and In, Au and Sn, and Au and Sb. In any of claims 8 to 1 2,
The solder containing Au is a mechanical quantity measuring device in which the solder containing Ge, Si, In, Sn, Ni, Sb, Ti, Cu, and Ag contains at least two kinds of elements and the rest is made of Au. .

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