JP3657817B2 - Grinding and cutting method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a grinding and cutting method for grinding and cutting a substrate on which two or more substrates are bonded.
[0002]
[Prior art]
There is a capacitive pressure sensor chip that detects pressure by detecting capacitance. This pressure sensor chip has a housing composed of a substrate having a predetermined space and a diaphragm disposed on the space of the substrate, a fixed electrode disposed on the substrate, and a movable electrode fixed to the diaphragm And. The diaphragm is deformed when subjected to pressure, but due to this deformation, the distance between the movable electrode and the fixed electrode is changed, and the electrostatic capacitance therebetween is changed. Based on the change in capacitance, the pressure received by the diaphragm can be measured.
[0003]
In such a pressure sensor chip, one using sapphire (artificial corundum) has been proposed for a substrate and a diaphragm constituting a housing. By using sapphire for the casing, even if the object to be measured is a corrosive physical fluid, the physical fluid can be directly received by the diaphragm and the pressure can be measured. In the formation of such a pressure sensor chip, a substrate on which a plurality of pressure sensor chips are formed is ground and cut to a predetermined dimension (die size) to form a plurality of chips once. In this case, first, two sapphire substrates, which are a sapphire substrate in which a pressure chamber or the like is formed, and a thin substrate in which a movable electrode or the like is formed to become a diaphragm are brought into close contact with each other. Then, using a rotated diamond blade (thin grindstone) made of a thin grindstone, the bonded substrates are ground and cut into individual chips (dicing).
[0004]
The two sapphire substrates are bonded to each other by polishing the bonded surfaces to a mirror surface and applying pressure while heating to obtain a strong adhesive force without using an adhesive. In this direct bonding, when gas enters between the two substrates and does not escape, a strong bonding cannot be obtained at that location. For this reason, when performing direct joining, the groove | channel for venting is previously formed so that gas may not remain on the joining surface at the time of bonding. This groove is formed with a predetermined area secured along the cutting line at the time of dicing described above.
[0005]
As described above, in the case where a plurality of chip regions are formed on one substrate and a plurality of chips are formed at once by dicing, it is natural that there is a chip formation region on the substrate. It is necessary to arrange a cutting area between them. In the cutting area (cutting line), since the shape of the chip is generally rectangular, areas having a width necessary for cutting are arranged in a grid pattern. That is, a plurality of vertical cutting lines and a plurality of horizontal cutting lines are formed orthogonally to each other.
[0006]
The cutting area is an area that disappears when dicing. For this reason, a pattern such as an overlay mark which is necessary for forming a chip but is not necessary for a completed chip is arranged. Therefore, the above-described gas venting groove and the like are unnecessary for the completed chip, but are necessary at the time of bonding, and are therefore arranged in the cutting region. Accordingly, the gas vent grooves are also formed in a lattice shape.
[0007]
[Problems to be solved by the invention]
Conventionally, since it has been configured as described above, there has been a problem that the pressure sensor chip is peeled off when the pressure sensor chip is ground and cut.
When dicing is performed, first, the substrate is separated by grinding and cutting along the above-described vertical cutting lines, and then the individual chips are separated by grinding and cutting along the horizontal cutting lines. In this case, it can be said that the columns are first separated, and then the individual chips are separated from the separated columns.
[0008]
When grinding and cutting along this horizontal cutting line, the vertical cutting surfaces that have already been cut are exposed in all rows, so that each time the blade collides with the cutting surface, it occurs on the chip. Will do. Then, the blade collides with the cut surface at the corner of each chip.
Conventionally, a gas venting groove is formed in the cutting area, and the pressure sensor chip is easily peeled off from the groove. Had occurred. If this gas vent groove is eliminated, the peeling of the joint at the time of grinding and cutting is eliminated, but this causes a defect when the two substrates are bonded together.
[0009]
The present invention has been made to solve the above-described problems, and is a bonding surface in the case where two substrates having gas venting grooves are bonded together and cut into individual chips. The purpose is to make it possible to suppress peeling.
[0010]
[Means for Solving the Problems]
According to the grinding and cutting method of the present invention, the first and second grooves for venting the end reaching the end surface of the first substrate are formed in a matrix with a predetermined width and a predetermined depth. The substrate is bonded to the first and second groove forming surfaces of the first substrate to form a bonded substrate, and the bonded substrate is ground and cut along the first groove by a rotating blade. In a grinding and cutting method in which a bonded substrate is ground and cut along a second groove by a rotating blade, the width of the second groove adjacent to the intersection of the first groove and the second groove is a predetermined length. It was narrower than other areas.
Since grinding and cutting are performed in this way, the width of the second groove on the cut end surface formed as a result of grinding and cutting along the first groove is narrower than other regions.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
Here, a pressure sensor chip formed by bonding two sapphire substrates will be described as an example.
First, the pressure sensor chip will be briefly described. As shown in the perspective view of FIG. 1A, a capacity chamber 101a is formed at the center of the main surface of the base 101. A diaphragm 102 is bonded to the main surface of the rim portion 101b surrounding the capacity chamber 101a. Due to the diaphragm 102, the capacity chamber 101a is sealed. The base 101 and the diaphragm 102 are made of sapphire.
[0012]
A fixed electrode 103 is fixedly disposed in the capacity chamber 101 a of the base 101. A movable electrode 104 is fixed to the diaphragm 102 on the side of the capacity chamber 101 a so as to face the fixed electrode 103. The movable electrode 104 is disposed at a substantially central portion of the diaphragm 102. Further, a reference electrode 105 is fixed on the side of the capacity chamber 101 a of the diaphragm 102 so as to face the fixed electrode 103. The reference electrode 105 is disposed so as to surround the fixed electrode 103.
Further, for example, the movable electrode 104 is connected to a pin (not shown) disposed through the base 101 in the periphery of the capacity chamber 101a.
[0013]
In the pressure sensor chip 100 configured as described above, a capacitor is formed by the fixed electrode 103 and the movable electrode 104. And if the diaphragm 102 receives pressure from the outside and the center part curves in the direction of the base 101, since the space | interval of the fixed electrode 103 and the movable electrode 104 will change, the capacity | capacitance between them will change. If the change in capacity is detected, the pressure received by the diaphragm 102 can be detected.
[0014]
Incidentally, a capacitance is also formed between the reference electrode 105 provided on the diaphragm 102 and the fixed electrode 103. However, since the reference electrode 105 is provided near the rim portion 101b, the amount of displacement due to the warping of the diaphragm 102 is smaller than that of the movable electrode 104 disposed in the center portion.
For example, the dielectric constant of air in the capacity chamber 101a varies depending on humidity. Due to the change, the capacitance generated between these electrodes also changes. However, if the change in capacitance between the fixed electrode 103 and the movable electrode 104 is captured based on the change in capacitance between the fixed electrode 103 and the reference electrode 105, the diaphragm can be used even if the dielectric constant of air in the capacitance chamber 101a changes. The displacement amount 102 can be detected without variation.
[0015]
In addition, as shown in FIG. 1B, the pressure sensor chip 100 is formed in a plurality on a single substrate 110, and the substrate 110 and a substrate (not shown) to be the diaphragm 102 are bonded together. After that, the above-described one sensor chip 100 is obtained by cutting the substrate 110 individually. Therefore, the base 101 is a part of the substrate 110. In addition, the board | substrate used as the diaphragm 102 is abbreviate | omitted in FIG.1 (b).
In the bonding, two sapphire substrates are bonded together, but the surfaces to be bonded are polished to a mirror surface, and pressure is applied while heating, so that a strong adhesive force can be obtained without using an adhesive. Yes.
[0016]
In this direct bonding, when gas enters between the two substrates and does not escape, a strong bonding cannot be obtained at that location. For this reason, when performing direct joining, the groove | channel 120 for degassing is previously formed so that gas may not remain on the joining surface at the time of bonding. The groove 120 is formed with a predetermined area secured along a cutting line at the time of grinding and cutting in dicing. Further, the groove 120 is formed to reach the end of the substrate.
[0017]
In this embodiment, the gas venting groove 120 arranged in the cutting region of the substrate 110 is composed of a wide groove 120a having a width of about 180 to 280 μm and a narrow groove 120b having a narrower width than the wide groove 120a. I was like that.
Further, the narrow groove 120b is arranged at the end of the side that constitutes a region to be one pressure sensor chip. Accordingly, the narrow groove 120b portion of the groove 120 extending in the vertical direction intersects at the intersection of the cutting regions of the substrate 110. Note that the depth of the groove may be about several μm.
[0018]
Here, as shown in FIG. 1B, a square region indicated by a one-dot chain line is a chip configuration region 100a that serves as a pressure sensor chip, and an outer region thereof serves as a cutting region. A width slightly narrower than the cutting area is almost the width of the blade for grinding and cutting. The width of the cutting area is the distance between the chips on the substrate, but the larger the number, the smaller the number of chips that can be formed in one substrate. You should do it. However, if the width is made too narrow and narrower than the width of the blade, the blade enters (cuts) into the chip formation region, and the cut chip becomes defective. For this reason, in general, the width of the cutting region is made slightly narrower than the width of the blade and then made as narrow as possible.
[0019]
By the way, a diamond blade for grinding and cutting a substrate made of sapphire has a width of about 200 to 300 μm. In such a case, as shown in FIG. 1D, the width of the narrow groove 120b is 50 to 100 μm. It should be about. Further, the narrow groove 120b is located within one side of the chip configuration region 100a? ? 5%? ? What is necessary is just a length of about. On the other hand, the wide groove 120a occupying most of the gas vent groove 120 formed on the substrate 110 has a width of about 180 to 280 μm as shown in FIG. The effect of venting is sufficiently obtained.
As described above, by narrowing the width of the gas vent groove 120 at the four corners of the chip configuration region 100a to be the narrow groove 120b, it is possible to suppress the peeling at the time of the above-described conventional disconnection during cutting. Become.
[0020]
The suppression of the peeling will be described below.
The degassing groove 120 needs to have a width of 180 to 280 μm over almost the entire area for degassing when the substrate 110 and a substrate (not shown) which is a diaphragm are bonded together.
On the other hand, the distance between adjacent chip constituent areas 100a serving as cutting areas is approximately equal to 200 to 300 μm in the width of the blade for grinding and cutting. There is not much difference between the widths.
[0021]
Under such circumstances, conventionally, the width of the gas vent groove is about 120 to 280 μm over the entire periphery of the chip configuration region. This is a state as shown in FIG. FIG. 2 shows an end surface that has already been cut in one direction. A gas vent groove 201 a is formed in the substrate 201, and the substrate 202 is bonded to the substrate 201. Then, by cutting the blade in a direction perpendicular to the end face and grinding and cutting, the chips are finally cut out.
At this time, as shown in FIG. 2A, if there is no difference in the width of the gas vent groove 201a with respect to the width of the blade, the substrate 201 is cut at the cut end face after cutting as shown in FIG. The edge of the substrate 202 is peeled off from the edge.
[0022]
In contrast, in this embodiment, the width of the gas vent groove is partially narrowed to about 50 to 100 μm at the end portion that has already been cut. This is a state as shown in FIG. FIG. 3 also shows an end face that has already been cut. A gas release groove 301 a is formed in the substrate 301, and the substrate 302 is bonded to the substrate 301.
In this case, as shown in FIG. 3A, since the width of the gas vent groove 301a is small and the difference is large with respect to the width of the blade, the substrate 302 and the substrate 302 are peeled off as shown in FIG. There is no.
[0023]
By the way, in the above embodiment, the width of the gas vent groove 120 is narrowed at the four corners of the chip configuration region 100a. That is, although the width of the gas vent groove 120 is narrowed at a total of eight corners of the chip 4 corners, the present invention is not limited to this. Since the blade cuts the substrate from one direction at the time of grinding and cutting, as shown in FIG. 4, most of the gas venting grooves 420 that form the chip constituent area 400a for processing are wide grooves 420a, and the chip constituent area 400a. Narrow grooves 420a may be arranged at two places in the four corners.
[0024]
In this case, after cutting in the vertical direction of FIG. 4, the blade may be moved from the right direction to the left direction in FIG.
Further, when the width of the gas vent groove is narrowed at the corner of the chip formation region, it may be gradually narrowed in a tapered shape as shown in FIG.
However, it is necessary to set an area for reducing the width of the grooves so that the grooves having a reduced width remain even after one of the grooves is ground and cut.
[0025]
【The invention's effect】
As described above, in the present invention, the first and second grooves for venting the end reaching the end surface of the first substrate are formed in a matrix with a predetermined width and a predetermined depth, The second substrate is bonded to the first and second groove forming surfaces of the first substrate to form a bonded substrate, and the bonded substrate is ground and cut along the first groove by a rotating blade. In a grinding and cutting method in which a bonded substrate is ground and cut along a second groove by a rotating blade, the width of the second groove adjacent to the intersection of the first groove and the second groove is set to a predetermined value. Narrower than other areas over the length.
Since grinding and cutting are performed in this way, the width of the second groove on the cut end surface formed as a result of grinding and cutting along the first groove is narrower than other regions. As a result, according to the present invention, when the rotating blade is cut into the portion of the second groove on the cut end face, an excellent effect is obtained that the peeling of the joint surface can be suppressed.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a configuration of a pressure sensor to which a grinding cutting method according to an embodiment of the present invention is applied.
FIG. 2 is a side view schematically showing a state of a cut end face by a conventional grinding and cutting method.
FIG. 3 is a side view schematically showing a state of a cut end face by the grinding cutting method of the present invention.
FIG. 4 is a plan view showing a state of a groove according to another embodiment of the present invention.
FIG. 5 is a plan view showing a state of a groove according to another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 100 ... Pressure sensor chip, 100a ... Chip structure area, 101 ... Base, 101a ... Capacity chamber, 101b ... Rim part, 102 ... Diaphragm, 103 ... Fixed electrode, 104 ... Movable electrode, 105 ... Reference electrode, 110 ... Substrate, 120: Gas vent groove, 120a: Wide groove, 120b: Narrow groove.

Claims (1)

Forming a first groove and a second groove for degassing at an end reaching the end face of the first substrate in a matrix with a predetermined width and a predetermined depth;
Bonding a second substrate to the first and second groove forming surfaces of the first substrate to form a bonded substrate;
Grinding and cutting the bonded substrate along the first groove by a rotating blade;
Grinding and cutting the bonded substrate along the second groove by the rotating blade,
A grinding and cutting method, wherein a width of the second groove adjacent to an intersection of the first groove and the second groove is narrower than other regions over a predetermined length.

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