JP3711910B2 - Manufacturing method of semiconductor mechanical quantity sensor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a semiconductor mechanical quantity sensor in which a semiconductor sensor chip is mounted on a base via an adhesive, and particularly relates to improvement of quantitativeness of the adhesive.
[0002]
[Prior art]
Conventionally, as a semiconductor type mechanical quantity sensor, there is a semiconductor type pressure sensor as disclosed in JP-A-10-170367.
[0003]
Here, the structure of the semiconductor pressure sensor will be briefly described with reference to FIG.
[0004]
As shown in FIG. 4, the semiconductor pressure sensor includes a semiconductor sensor chip 11 on which a diaphragm 11 a that can be displaced by an applied pressure is formed, and a glass pedestal 12 that fixes the semiconductor sensor chip 11. .
[0005]
Then, a plurality of piezoresistors (strain gauges) 13 formed on the diaphragm 11a detect the strain of the diaphragm 11a caused by receiving pressure, and the pressure applied to the semiconductor pressure sensor is detected.
[0006]
Further, the semiconductor sensor chip 11 is bonded onto the package material 15 with an adhesive 14 via the glass pedestal 12.
[0007]
Here, a manufacturing process of such a semiconductor pressure sensor will be briefly described with reference to FIG.
[0008]
First, as shown in FIG. 5A, a semiconductor wafer 17 is prepared. Although not shown, a glass pedestal is bonded to the semiconductor wafer 17 in advance.
[0009]
Subsequently, the semiconductor wafer 17 is divided and cut into a plurality of semiconductor sensor chips 11. The diaphragm 11 a and the piezoresistor 13 (not shown) formed on the semiconductor sensor chip 11 are formed in the state of the semiconductor wafer 17.
[0010]
Subsequently, as shown in FIG. 5B, the adhesive 14 is applied to a predetermined region on the package material 15 by using, for example, a dispensing method.
[0011]
The dispensing method is a method in which the adhesive 14 is filled in a syringe and the adhesive 14 is discharged by air pressure using a device called a dispenser.
[0012]
Here, since the adhesive 14 is a material having high fluidity, if the force applied to the semiconductor sensor chip 11 and the glass pedestal 12 from the die mounting device during the die mounting process, which will be described later, is uneven, In addition, the thickness of the adhesive 14 may be non-uniform.
[0013]
Therefore, in the conventional publication, a large number of beads 16 of a predetermined size are mixed in the adhesive 14, and the thickness of the adhesive 14 is defined by the beads 16, so that the thickness of the adhesive 14 for each sensor is made uniform. Yes.
[0014]
Subsequently, as shown in FIG. 5C, the semiconductor sensor chip 11 and the glass pedestal 12 that are divided and cut are mounted on the adhesive 14 by using the die mount device 18.
[0015]
Finally, as shown in FIG. 5 (d), the adhesive 14 interposed between the glass pedestal 12 and the packaging material 15 is cured by applying heat, whereby the semiconductor sensor chip 11 and the glass pedestal 12 are cured. Is fixed onto the package material 15.
[0016]
[Problems to be solved by the invention]
However, in the above prior art, the dispersibility of the beads 16 mixed in the adhesive 14 during the step of applying the adhesive 14 to a predetermined region on the package material 15 as shown in FIG. In a bad case, as shown in FIG. 6, the semiconductor sensor chip 11 and the glass pedestal 12 may be fixed in an inclined state with respect to the package material 15.
[0017]
As a result, when thermal distortion occurs in the package material 15 due to a temperature change, the thermal distortion transmitted from the package material 15 to the diaphragm 11a of the semiconductor sensor chip 11 differs from sensor to sensor, resulting in non-uniform sensor characteristics. End up.
[0018]
Therefore, in view of the above problems, the object of the present invention is to improve the quantitativeness of the adhesive without using beads in the semiconductor mechanical quantity sensor in which the semiconductor sensor chip is mounted on the base via the adhesive. It is to provide a manufacturing method.
[0019]
[Means for Solving the Problems]
The method of manufacturing a semiconductor mechanical quantity sensor according to claim 1 includes: a first step of applying a liquid adhesive on one side of the semiconductor wafer; and applying heat to the adhesive applied to the one side of the semiconductor wafer. A second step of semi-curing, a third step of dividing and cutting a semiconductor wafer to form a plurality of semiconductor sensor chips having a displacement portion that is displaced by application of a mechanical quantity and detecting displacement of the displacement portion; and a semiconductor sensor chip And a fourth step of mounting the semiconductor sensor chip on the base through the adhesive, and a fifth step of heating the adhesive again to cure the adhesive and fixing the semiconductor sensor chip on the base. Yes.
[0020]
According to the first aspect of the present invention, after performing the first step of applying the liquid adhesive on one surface side of the semiconductor wafer, the third step of dividing and cutting the semiconductor wafer into a plurality of semiconductor sensor chips is performed. Therefore, the thickness of the adhesive can be made uniform for each chip without using beads.
[0021]
Accordingly, when thermal distortion occurs in the base due to temperature change, the thermal distortion transmitted from the base to the semiconductor sensor chip can be made uniform, so that the sensor characteristics can be made uniform.
[0022]
In the present invention, since the fourth step of mounting the semiconductor sensor chip on the base is performed after performing the second step of semi-curing by applying heat to the adhesive, the self-weight of the semiconductor sensor chip is used. The deformation of the adhesive can be prevented.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to a semiconductor pressure sensor will be described with reference to the drawings. The semiconductor pressure sensor of this embodiment is used for detecting the pressure of intake air in an intake manifold in a vehicle engine, for example.
[0024]
FIG. 1 shows the structure of the semiconductor pressure sensor of this embodiment.
[0025]
First, as shown in FIG. 1, a diaphragm 1a is formed on the semiconductor sensor chip 1 by anisotropic etching, and a piezoresistor (strain gauge) for detecting the displacement of the diaphragm 1a is formed on the surface of the diaphragm 1a. ) 2 is formed in plural.
[0026]
Although three piezoresistors 2 are shown in FIG. 1, four piezoresistors 2 are actually formed on the surface of the diaphragm 1a, and the four piezoresistors 2 constitute a full bridge circuit. Yes.
[0027]
Although not shown, the piezoresistor 2 is electrically connected to an external signal processing circuit by a wiring pattern and a bonding wire made of an Al thin film formed on the semiconductor sensor chip 1.
[0028]
Further, the semiconductor sensor chip 1 is anodically bonded to the glass pedestal 3, whereby a vacuum chamber 4 is formed between the semiconductor sensor chip 1 and the glass pedestal 3.
[0029]
And the diaphragm 1a is displaced according to the differential pressure | voltage of the pressure applied to the surface, and the pressure of the vacuum chamber 4. FIG.
[0030]
In this case, each piezoresistor 2 has its resistance value increased or decreased according to the change in pressure applied to the diaphragm 1a, and the signal processing circuit amplifies the potential difference generated by the increase or decrease in resistance value. Thus, the sensor output is obtained.
[0031]
Further, the semiconductor sensor chip 1 and the glass pedestal 3 are bonded to a package material 5 made of an epoxy resin or the like by a thermosetting adhesive 6.
[0032]
Hereafter, the manufacturing process of the semiconductor type pressure sensor of this embodiment is demonstrated using FIG.2 and FIG.3.
[0033]
First, as shown in FIG. 2A, a semiconductor wafer 7 is prepared. Although not shown, a glass pedestal is bonded to the semiconductor wafer 7 in advance.
[0034]
Subsequently, a first step of coating the entire surface of the silicon-based thermosetting adhesive 6 on the back surface side of the semiconductor wafer 7 by a screen printing method using the screen printing apparatus 8 as shown in FIG. Execute.
[0035]
The screen printing apparatus 8 includes a screen 8a having an opening 8b and a roll 8c having an adhesive 6 applied around the screen 8a. FIG. 3A is a diagram showing a state before a process of disposing a semiconductor wafer 7 to be described later in the opening 8b of the screen 8a.
[0036]
Here, the process of applying the adhesive 6 to the back surface side of the semiconductor wafer 7 will be described. First, as shown in FIG. 3B, which is a cross-sectional view taken along the line AA ′ in FIG. The semiconductor wafer 7 is disposed in the opening 8b so that the back surface side 7a is exposed.
[0037]
Thereafter, the roll 8c, to which the adhesive 6 has been previously applied, is rotated counterclockwise while proceeding in the direction of the arrow in the drawing, so that the thickness of the semiconductor wafer 7 is as shown in FIG. The adhesive 6 can be applied to the entire back surface 7a of the semiconductor wafer 7 with a uniform thickness by the difference T between the depth of the opening 8b of the screen 8a.
[0038]
Thereafter, when the semiconductor wafer 7 coated with the adhesive 6 is removed from the screen 8a, the state shown in FIG. 2B is obtained.
[0039]
Subsequently, a second step is performed in which heat is applied to the adhesive 6 applied to the back surface 7a of the semiconductor wafer 7 in the first step so as to be semi-cured.
[0040]
The semi-curing in the second step means that the semiconductor sensor chip 1 and the glass pedestal 3 when the fourth step of mounting the semiconductor sensor chip 1 and the glass pedestal 3 and the adhesive 6 on the package material 5 described later are executed. The adhesive 6 is not deformed by its own weight, and the adhesive 6 is hardened to a state where the adhesive 6 is not completely hardened and the adhesive force of the adhesive 6 remains. For example, the adhesive 6 is cured until it has an elastic modulus in the range of about 1/100 to about 1/2 of the elastic modulus in a completely solidified state.
[0041]
The temperature and time required for curing the adhesive 6 vary depending on the type of the adhesive. For example, in the present embodiment, a silicon-based thermosetting adhesive is used as the adhesive 6. In order to semi-cure the adhesive 6, it is appropriate to apply heat at a temperature of about 150 ° C. for about 3 minutes.
[0042]
Subsequently, a third step of dividing and cutting the semiconductor wafer 7 into a plurality of semiconductor sensor chips 1 is performed. The diaphragm 1 a and the piezoresistor 2 (not shown) formed on the semiconductor sensor chip 1 are formed in the state of the semiconductor wafer 7.
[0043]
Subsequently, as shown in FIG. 2 (c), a fourth step of mounting the semiconductor sensor chip 1, the glass pedestal 3, and the adhesive 6 on the package material 5 using the die mount device 9 is performed. Execute.
[0044]
Finally, as shown in FIG. 2 (d), a fifth process is performed in which the adhesive 6 is heated again to be fully cured, thereby fixing the semiconductor sensor chip 1 and the glass pedestal 3 on the package material 5. Do.
[0045]
The main curing in the fifth step is curing until the semiconductor sensor chip 1 and the glass pedestal 3 are fixed on the package material 5.
[0046]
In order to fully cure the adhesive 6, it is appropriate to apply heat at a temperature of about 150 ° C. for about 60 minutes.
[0047]
As described above, in the method of manufacturing the semiconductor pressure sensor according to this embodiment, after the first step of applying the adhesive 6 to the entire back surface 7a of the semiconductor wafer 7 is executed, the semiconductor wafer 7 is attached to the plurality of semiconductor sensor chips 1. Since the 4th process of dividing and cutting is performed, the thickness of the adhesive 6 can be made uniform for each sensor without using beads.
[0048]
Thereby, when thermal distortion occurs in the package material 5 due to temperature change, the thermal distortion transmitted from the package member 5 to the diaphragm 1a of the semiconductor sensor chip 1 can be made uniform, so that the characteristics of the sensor are made uniform. Can do.
[0049]
In the present embodiment, after performing the second step of semi-curing by applying heat to the adhesive 6, the fourth step of mounting the semiconductor sensor chip 1, the glass pedestal 3, and the adhesive 6 on the package material 5 is performed. Since it is executed, deformation of the adhesive 6 due to the weight of the semiconductor sensor chip 1 and the glass pedestal 3 can be prevented.
[0050]
Furthermore, by applying the manufacturing method as in the present embodiment, the beads that have been mixed in the adhesive 6 for the purpose of making the thickness of the adhesive 6 uniform for each sensor in the prior art are unnecessary. As a result, the cost can be reduced and the manufacturing process can be simplified.
[0051]
In the prior art, the adhesive is applied to each individual semiconductor sensor chip. However, in the manufacturing method according to the present embodiment, the adhesive 6 is applied to each semiconductor wafer 7. Can be simplified.
[0052]
In addition, this invention is not restricted to the said embodiment, It can apply to various aspects.
[0053]
For example, the present invention is not limited to the semiconductor pressure sensor as in the present embodiment, but can be applied to other mechanical quantity sensors such as an acceleration sensor.
[0054]
The semiconductor pressure sensor may be of a type that introduces the pressure of the measurement medium to the diaphragm 1a through the glass pedestal 3.
[Brief description of the drawings]
FIG. 1 is a diagram showing a structure of a semiconductor pressure sensor according to an embodiment of the present invention.
FIGS. 2A to 2D are views showing a manufacturing process of a semiconductor pressure sensor according to an embodiment of the present invention. FIGS.
FIGS. 3A to 3C are diagrams showing an adhesive application process of a semiconductor pressure sensor according to an embodiment of the present invention. FIGS.
FIG. 4 is a diagram showing a structure of a conventional semiconductor pressure sensor.
FIGS. 5A to 5D are diagrams showing a manufacturing process of a conventional semiconductor pressure sensor.
FIG. 6 is a diagram showing a problem of a conventional semiconductor pressure sensor.
[Explanation of symbols]
1 ... Semiconductor sensor chip,
1a ... diaphragm,
2 ... Piezoresistor (strain gauge),
3 ... Glass pedestal,
4 ... Vacuum chamber,
5 ... Packaging materials,
6 ... Silicon thermosetting adhesive,
7 ... Semiconductor wafer,
7a: The back side of the semiconductor wafer,
8: Screen printing device,
8a ... screen,
8b ... the opening of the screen,
8c ... roll,
9 ... Die mount device,
T: Difference between the thickness of the semiconductor wafer and the depth of the opening of the screen.

Claims (1)

A first step of applying a liquid adhesive on one side of the semiconductor wafer;
A second step in which heat is applied to the adhesive applied to one side of the semiconductor wafer and semi-cured;
A third step of dividing and cutting the semiconductor wafer to form a plurality of semiconductor sensor chips that have a displacement portion that is displaced by application of a mechanical quantity and that detects displacement of the displacement portion;
A fourth step of mounting the semiconductor sensor chip on a base via the adhesive;
A method of manufacturing a semiconductor mechanical quantity sensor, comprising: a fifth step in which heat is applied again to the adhesive to perform main curing, and the semiconductor sensor chip is fixed onto the base.

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