JP2004132811A - Force detecting element, and manufacturing method of force detecting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a force detecting element with superior reliability by preventing intrusion of dust into a gap between a semiconductor substrate and a force transmitting block. <P>SOLUTION: Since a gage part 16 and a silicon single crystal substrate 10 surface of its periphery are sealed in a closed space formed by joining the force transmitting block 12 and a dust intrusion preventing part 18, no dust will intrude between the silicon single crystal substrate 10 and the force transmitting block 12, and there will be no adverse effect to force detecting performance. As a result, reliability of the force detecting element is improved. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a force detection element and a method for manufacturing the force detection element, and more particularly to a force detection element using a piezoresistive element and a method for manufacturing the same.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a small force detecting element using a piezoresistive element is known as a force detecting element used for detecting an in-cylinder combustion pressure of an engine. A piezoresistive element is an element in which the resistivity of the portion where the distortion occurs is changed according to the distortion (stress deformation). This piezoresistive element is generally constituted by a gauge resistor formed on the main surface of a single crystal silicon (Si) substrate by a semiconductor manufacturing technique.
[0003]
For example, on a Si substrate having a (110) plane as a main surface, four gauge resistors having a piezoresistance effect are formed in a mesa shape in the <100> direction and the <110> direction to constitute a Wheat Easton bridge, A force detection element in which a force transmission block is disposed on the Wheat Easton bridge has been proposed (see Patent Document 1).
[0004]
In this force detection element, when a force is applied to the force transmission block, stress is transmitted from the force transmission block in the thickness direction of the Si substrate. Therefore, a voltage is applied so that current flows in a direction perpendicular to the direction of the stress. To do. And since the piezoresistance effect of the gauge resistance generated according to the stress is different between the <100> direction and the <110> direction, a difference occurs in the resistance value, and this difference in resistance value is detected as a voltage difference. The force acting on the force transmission block is detected.
[0005]
In order to manufacture this force detection element, the Si wafer on which the gauge resistance is formed and the glass wafer are anodically bonded and then diced.
[0006]
[Patent Document 1]
JP-A-8-271363
[Problems to be solved by the invention]
However, in the conventional force detection element in which the gauge resistance is formed in a mesa shape, for example, dust such as chips generated during dicing enters into the gap between the Si substrate and the force transmission block caused by the mesa step. was there. When chips enter the gap between the Si substrate and the force transmission block, the stress is not accurately transmitted from the force transmission block to the Si substrate, and the reliability of the force detection element decreases.
[0008]
The present invention has been made to solve the above problems, and an object of the present invention is to prevent dust from entering the gap between the semiconductor substrate and the force transmission block, and to have a highly reliable force detection element. Is to provide.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a force sensing element of the present invention is formed in a mesa shape on one main surface of a semiconductor substrate, and a gauge portion whose electrical resistance changes when pressed, An electrode electrically connected to the gauge portion so as to form a current path together with the gauge portion; and a force transmission block for transmitting an applied force in a thickness direction of the semiconductor substrate by pressing the gauge portion; And a sealing member which is formed on the main surface of the semiconductor substrate and seals the gauge portion together with the force transmission block.
[0010]
In the force detection element of the present invention, since the sealing member that seals the gauge portion together with the force transmission block is formed in a mesa shape on the main surface of the semiconductor substrate, dust enters the gap between the semiconductor substrate and the force transmission block. Is prevented. As a result, the reliability of the force detection element is improved.
[0011]
In the above-described force detection element, the sealing member may be formed on the main surface of the semiconductor substrate so as to have a step only on the gauge portion side, or may be formed in a mesa shape.
[0012]
Further, the force detection element is for sealing each of the gauge portions on the main surface of the semiconductor wafer in which a plurality of gauge portions are formed in a mesa shape on one main surface. A plurality of sealing members are formed in a mesa shape, and the semiconductor wafer and a block substrate on which a plurality of force transmission block forming portions are formed are bonded so as to seal the gauge portion together with the sealing member, The semiconductor wafer to which the block substrate is bonded can be manufactured by dicing between the blocks together with the block substrate.
[0013]
According to this method, not only after manufacturing but also in the manufacturing process, chips generated during dicing are prevented from entering the gap between the semiconductor substrate and the force transmission block, and the force detection is more reliable. An element can be obtained.
[0014]
Further, instead of forming a mesa-shaped sealing member on the main surface of the semiconductor substrate, the gauge part may be sealed before dicing with a sealing material. That is, the semiconductor substrate, a mesa-like shape formed on one main surface of the semiconductor substrate, and an electric resistance that changes when pressed, and a current path together with the gauge portion, A force detection device for manufacturing a force detection element comprising: an electrode electrically connected to a gauge portion; and a force transmission block that transmits an applied force in a thickness direction of the semiconductor substrate by pressing the gauge portion. The element manufacturing method includes joining a semiconductor wafer having a plurality of gauge portions formed in a mesa shape on one main surface and a block substrate having a plurality of force transmission block forming portions, and using the sealing material to A force sensing element is manufactured by sealing a portion and dicing the semiconductor wafer with the gauge portion sealed between the blocks together with the block substrate. This method can also prevent chips generated during dicing from entering the gap between the semiconductor substrate and the force transmission block.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
As shown in FIGS. 1A and 1B and FIGS. 2A and 2B, the force detection element according to the first embodiment includes a rectangular n-type silicon single crystal substrate 10 and glass. The force transmission block 12 made of is joined and comprised. The main surface on the bonding surface side of the silicon single crystal substrate 10 is a pair of electrode arrangement portions 14 arranged on both sides of the substrate longitudinal direction, and a straight line formed along the longitudinal direction so as to bridge both electrode arrangement portions. A gauge portion 16, a lead portion 15 that connects the electrode placement portion 14 and the gauge portion 16, and a dust intrusion prevention portion 18 that surrounds the gauge portion 16 are provided. The dust intrusion prevention unit 18 is formed by continuing a pair of parallel parts parallel to the gauge part 16 and a pair of vertical parts perpendicular to the gauge part 16 along a square side.
[0016]
Each of the electrode placement portion 14, the lead portion 15, the gauge portion 16, and the dust intrusion prevention portion 18 forms a p-type semiconductor layer by diffusing boron on the surface of the n-type silicon single crystal substrate 10. By etching to a predetermined depth (usually about 2 to 3 μm) with a pattern, a mesa shape is formed. Thereby, the p-type semiconductor is disposed in the vicinity of the surface of the mesa.
[0017]
The surface of the silicon single crystal substrate 10 on which the gauge portion 16 and the like are formed is covered with an insulating film 20 such as a silicon oxide (SiO ₂ ) film. Further, a metal electrode 24 such as aluminum is formed on the surface of the electrode placement portion 14 via an insulating film 20, and the electrode placement portion 14 and the metal electrode 24 are brought into contact with the insulating film 20 on the electrode placement portion 14. A contact hole 22 is provided for this purpose.
[0018]
The force transmission block 12 is disposed on the gauge unit 16 so as to transmit the force applied to the top surface thereof to the gauge unit 16 vertically, and the outer periphery thereof is parallel to the dust intrusion prevention unit 18 and the upper surface of the vertical unit. Is disposed on the dust intrusion prevention unit 18 so as to be positioned at a substantially central portion. By arranging in this way, the gauge portion 16 and the periphery thereof are sealed in a sealed space formed by joining the force transmission block 12 and the dust intrusion prevention portion 18, and force transmission with the silicon single crystal substrate 10 is performed. Dust does not enter between the block 12.
[0019]
In this force detection element, when a force is applied to the top surface of the force transmission block 12, the force transmission block 12 transmits the force to the gauge portion 16 perpendicularly. Thereby, the piezoresistance coefficient of the gauge part 16 changes, and the voltage applied between electrodes changes. The force acting on the force transmission block 12 can be detected by this voltage change.
[0020]
Next, a method for manufacturing the force detection element will be described with reference to FIGS. As shown in FIG. 3A, a plurality of unit elements each including the electrode placement portion 14, the lead portion 15, the gauge portion 16, the dust intrusion prevention portion 18, and the metal electrode 24 are formed on one main surface. A glass that includes a silicon wafer 30 and a plurality of portions 32 to be processed into the force transmission block 12 and is thinned so as to easily remove the unnecessary portion 34 between adjacent force transmission blocks 12 by grooving the surface. A wafer 36 is prepared.
[0021]
Then, the surfaces of the glass wafer 36 and the silicon wafer 30 that have been grooved so that the outer periphery of the force transmission block 12 is positioned at the substantially central portion of the parallel portion of the dust intrusion prevention portion 18 and the upper surface of the vertical portion. The contact portion is firmly attached to the surface on which the gauge portion 16 or the like is formed, and the contact portion is firmly fixed by electrostatic bonding such as anodic bonding. Thereby, the gauge part 16 and its periphery are sealed in the sealed space formed by joining the part 32 and the dust intrusion prevention part 18.
[0022]
Next, as shown in FIG. 3B, the unnecessary portion 34 of the glass wafer 36 is moved up and down a plurality of times by a cutting device 38 such as a dicing saw to be removed by cutting. As a result, the unnecessary portion 34 is removed from the glass wafer 36, and the portion remaining on the silicon wafer 30 functions as the force transmission block 12. In this cutting process, a large amount of chips are generated on the glass wafer 36, but the chips do not enter the sealed space.
[0023]
Next, as shown in FIG. 3C, in order to protect the electrodes, the entire surface of the silicon wafer 30 including the force transmission block 12 is covered with a protective film 40 such as a resin, and then a cutting device such as a dicing saw or the like. The silicon wafer 30 is diced by 38 to cut out individual force detection elements. Finally, as shown in FIG. 3D, the protective film 40 is removed to obtain the force detection element shown in FIG.
[0024]
As described above, the force detection element according to the present embodiment has the sealed space formed by joining the force transmission block 12 and the dust intrusion prevention unit 18 to the surface of the gauge unit 16 and the surrounding silicon single crystal substrate 10. Since it is sealed inside, dust does not enter between the silicon single crystal substrate 10 and the force transmission block 12, and the force detection performance is not adversely affected. As a result, the reliability of the force detection element is improved.
[0025]
Further, in the manufacturing process, dicing is performed after the glass wafer 36 including the portion 32 processed into the force transmission block 12 and the silicon wafer 30 are joined and the gauge portion 16 and its periphery are sealed in a sealed space. It is possible to prevent chips generated during dicing from entering between the silicon single crystal substrate 10 and the force transmission block 12. Thereby, the force detection element excellent in reliability can be manufactured.
[0026]
In addition, although the example which forms a gauge part, a dust intrusion prevention part, etc. in mesa shape was demonstrated above, as shown to FIG.4 (A)-(D), n with which the p-type semiconductor layer was formed in the surface With respect to the silicon single crystal substrate 10, the gauge portion 42 may be pressed by the force transmission block 12 by removing the periphery of the gauge portion 42 at a predetermined depth by etching or the like while leaving the dust intrusion prevention portion 44. Also in this case, since the gauge portion 42 and the surrounding silicon single crystal substrate 10 surface are sealed in a sealed space formed by joining the force transmission block 12 and the dust intrusion prevention portion 44, Dust does not enter between the crystal substrate 10 and the force transmission block 12, and an effect similar to that of the force detection element according to the first embodiment can be obtained. In addition, about the same component as the force detection element which concerns on 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.
(Second Embodiment)
In the second embodiment, an example of a force detection element in which a through hole is provided in the center of the force transmission block and an electrode is extracted from the through hole will be described.
[0027]
As shown in FIGS. 5A to 5C, the force detection element according to the second embodiment is configured by joining an n-type silicon single crystal substrate 50 and a glass force transmission block 52. Has been. The force transmission block 52 is formed in a rectangular parallelepiped shape whose outer shape is substantially the same as that of the silicon single crystal substrate 50.
[0028]
The main surface on the bonding surface side of the silicon single crystal substrate 50 has a substantially circular electrode arrangement portion 54 arranged at the center of the substrate, a square-shaped gauge portion 56 surrounding the electrode arrangement portion 54, and four corners of the gauge portion 56. Four lead portions 58 that bridge the corner portion and the electrode placement portion 54 and a dust intrusion prevention portion 60 that surrounds the gauge portion 56 are provided. The dust intrusion prevention unit 60 has a pair of parallel parts parallel to the gauge part 56 and a pair of vertical parts perpendicular to the gauge part 56, which are made continuous with each other along the square side. It is formed around. The dust intrusion prevention unit 60 is formed such that the outer periphery thereof coincides with the outer periphery of the silicon single crystal substrate 50.
[0029]
Each of the electrode placement portion 54, the gauge portion 56, the lead portion 58, and the dust intrusion prevention portion 60 is an n-type silicon single crystal having a p-type semiconductor layer formed on the surface in the same manner as in the first embodiment. The substrate 50 is etched from the surface to form a mesa shape.
[0030]
The surface of the silicon single crystal substrate 50 on which the gauge portion 56 and the like are formed is covered with an insulating film (not shown). A metal electrode 62 such as aluminum is formed on the surface of the electrode placement portion 54 via this insulating film, and the insulating film on the electrode placement portion 54 is used to contact the electrode placement portion 54 and the metal electrode 62. A contact hole 64 is provided. In this example, two pairs of opposing metal electrodes 62 are arranged, but as shown in FIG. 6, the metal electrodes can be arranged in different layouts.
[0031]
The force transmission block 52 is disposed on the gauge portion 56 so as to transmit the force applied to the top surface thereof to the gauge portion 56 vertically, and the outer periphery thereof coincides with the outer periphery of the dust intrusion prevention portion 60. It is disposed on the dust intrusion prevention unit 60. With this arrangement, the surface of the silicon single crystal substrate 50 in the vicinity of the outside of the gauge portion 56 is sealed in a sealed space formed by joining the force transmission block 52 and the dust intrusion prevention portion 60. This prevents dust from entering this space.
[0032]
On the other hand, as shown in FIG. 5, when the diameter of the through hole 66 provided in the center of the force transmission block 52 is larger than the diameter of the circular electrode arrangement portion 54, the force transmission block 52 and the electrode arrangement portion are arranged. Since there is a gap between the silicon single crystal substrate 50 and the force transmission block 52, there is room for dust to enter.
[0033]
Next, a method for manufacturing the force detection element according to the second embodiment will be described with reference to FIG. This force detection element can be basically manufactured by the same method as in the first embodiment, but there are differences depending on the structure of the force detection element as described below.
[0034]
First, as shown in FIG. 7, silicon having a plurality of unit elements each including an electrode arrangement portion 54, a gauge portion 56, a lead portion 58, a dust intrusion prevention portion 60, and a metal electrode 62 formed on one main surface. A wafer 70 and a glass wafer 74 including a plurality of portions 72 in which through holes 66 are provided in advance and processed into the force transmission block 52 are prepared. Unlike the first embodiment, the glass wafer 74 is not grooved. For this reason, the periphery of the unnecessary portion 76 removed along the dicing line is joined with a width wider than the cut width.
[0035]
Then, the glass wafer 74 and the silicon wafer 70 are overlapped so that the through hole 66 is positioned above the electrode placement portion 54, and the contact portion is firmly fixed by electrostatic bonding such as anodic bonding. Thereby, the surface of the silicon single crystal substrate 50 in the vicinity of the outside of the gauge portion 56 (on the side opposite to the center point of the element) is in a sealed space formed by joining the portion 72 and the dust intrusion prevention portion 60. Sealed. On the other hand, a slight gap is formed between the portion 72 and the electrode arrangement portion 54.
[0036]
Next, the through hole 66 is filled with a sealing material 68 that can be removed by post-processing, and the through hole 66 is temporarily filled. As such a sealing material, wax, gel, resin, or the like can be used. Thereafter, the silicon wafer 70 and the glass wafer 74 are diced together by the cutting device 38 to cut out individual force detection elements. In this dicing process, a large amount of chips are generated, but since the periphery of the unnecessary portion 76 is joined with a width wider than the cut width, the chips do not enter the sealed space. Further, since the through-hole 66 is also filled with the sealing material 68, the chips do not enter from the gap between the portion 72 and the electrode arrangement portion 54. Finally, post-processing is performed to remove the sealing material 68, and the force detection element shown in FIG. 5 is obtained.
[0037]
As described above, the force detection element of the present embodiment is formed by bonding the surface of the silicon single crystal substrate 50 in the vicinity of the outside of the gauge portion 56 to the force transmission block 52 and the dust intrusion prevention portion 60. Since it is sealed in the closed space, dust does not enter the space and the force detection performance is not adversely affected. As a result, the reliability of the force detection element is improved.
[0038]
Also in the manufacturing process, the periphery of the unnecessary portion 76 removed by dicing is joined with a width wider than the cut width, and the through hole 66 is temporarily filled with the sealing material 68 before dicing. It is possible to prevent chips generated during dicing from entering between the single crystal substrate 50 and the force transmission block 52. Thereby, the force detection element excellent in reliability can be manufactured.
[0039]
In the above, the diameter of the through hole 66 provided in the center of the force transmission block 52 is larger than the diameter of the circular electrode arrangement portion 54, and a gap is formed between the force transmission block 52 and the electrode arrangement portion 54. Although the configuration example has been described, as shown in FIG. 8, the diameter of the through hole 66 is made smaller than the diameter of the circular electrode arrangement portion 54 on the joint surface, so that the gauge portion 56 and its periphery can be connected to the force transmission block. 52, the electrode arrangement portion 54, and the dust intrusion prevention portion 60 can be sealed in a sealed space formed by joining.
[0040]
In this structure, since no gap is generated between the force transmission block 52 and the electrode arrangement portion 54, dust does not enter between the silicon single crystal substrate 50 and the force transmission block 52, and the reliability of the force detection element is reduced. Will improve. Further, it is not necessary to fill the through hole 66 with the sealing material 68 before dicing in order to prevent chips from entering, and the manufacturing process is simplified.
[0041]
In the first and second embodiments, an SOI (Silicon on Insulator) substrate may be used as the semiconductor substrate.
[0042]
【The invention's effect】
As described above, according to the force detection element of the present invention, it is possible to prevent dust from entering the gap between the semiconductor substrate and the force transmission block, thereby improving the reliability.
[0043]
Further, according to the method for manufacturing a force detection element of the present invention, chips generated during dicing are prevented from entering the gap between the semiconductor substrate and the force transmission block even in the manufacturing process, and further excellent in reliability. The effect that the force-detecting element can be obtained is obtained.
[Brief description of the drawings]
FIG. 1A is a perspective view showing a structure of a force detection element according to a first embodiment, and FIG. 1B is a plan view.
2A is an end view when the force detection element according to the first embodiment is cut along an AA line, and FIG. 2B is an end view when the line is cut along a BB line.
FIGS. 3A to 3D are diagrams for explaining a manufacturing process of the force detection element according to the first embodiment; FIGS.
4A is a perspective view showing a modified example of the force detection element according to the first embodiment, FIG. 4B is a plan view, and FIG. 4C is an AA line of the modified element. It is an end view at the time of cut | disconnecting, (D) is an end view at the time of cut | disconnecting the element of a modification with a BB line.
FIG. 5A is a plan view showing a structure of a force detection element according to a second embodiment, and FIG. 5B is an end view when the element of FIG. (C) is a perspective view of the element of (A).
FIG. 6 is a plan view showing a modification of the force detection element according to the second embodiment.
FIG. 7 is a diagram for explaining a manufacturing process of the force detection element according to the second embodiment.
FIG. 8 is an end view showing a modification of the force detection element according to the second embodiment.
[Explanation of symbols]
10, 50 Silicon single crystal substrate 12, 52 Force transmission block 16, 56 Gauge part 18, 60 Dust intrusion prevention part 30, 70 Silicon wafer 36, 74 Glass wafer 38 Cutting device 66 Through hole 68 Sealing material

Claims (4)

A semiconductor substrate;
A gauge part that is formed in a mesa shape on one main surface of the semiconductor substrate and whose electrical resistance changes when pressed,
An electrode electrically connected to the gauge portion so as to form a current path with the gauge portion;
A force transmission block that transmits the applied force in the thickness direction of the semiconductor substrate by pressing the gauge portion;
A sealing member that is formed on the main surface of the semiconductor substrate and seals the gauge portion together with the force transmission block;
Force sensing element with 2. The force detection element according to claim 1, wherein the sealing member is formed to have a step on the main surface only on the gauge portion side, or formed in a mesa shape on the main surface. A plurality of gauge members are formed in a mesa shape on one main surface, and a plurality of sealing members for sealing each of the gauge portions are formed in a mesa shape on the main surface of the semiconductor wafer on which the gauge portions are formed. Forming,
Bonding the semiconductor wafer and a block substrate on which a plurality of force transmission block forming portions are formed so as to seal the gauge portion together with the sealing member,
The semiconductor wafer to which the block substrate is bonded is diced between the blocks together with the block substrate to manufacture a force detection element.
A manufacturing method of a force detection element. A semiconductor substrate, a gauge portion formed in a mesa shape on one main surface of the semiconductor substrate, and an electric resistance changing when pressed, and the gauge portion so as to form a current path together with the gauge portion And a force transmission block that transmits an applied force in the thickness direction of the semiconductor substrate by pressing the gauge portion. A manufacturing method comprising:
Bonding a semiconductor wafer in which a plurality of gauge portions are formed in a mesa shape on one main surface and a block substrate in which a plurality of force transmission block forming portions are formed,
Sealing the gauge part with a sealing material;
The semiconductor wafer in which the gauge portion is sealed is diced between the blocks together with the block substrate to manufacture a force detection element.
A manufacturing method of a force detection element.

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