JP4320892B2 - Bonding substrate cutting method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of cutting a bonded substrate in which a semiconductor substrate on which a circuit is formed and a second substrate that plays an auxiliary role are bonded and the bonded substrate is divided into individual chips along a scribe line. about the law.
[0002]
[Problems to be solved by the invention]
As shown in FIG. 7, a semiconductor dynamic quantity sensor, for example, a pressure sensor chip 1 is formed by using a silicon chip 2 on which a diaphragm 2a is formed and a detection circuit (not shown) made of a diffusion piezoresistor is formed. It is configured to be supported on a glass support base 3 having a through hole 3a communicating with 2a. In this case, in manufacturing the pressure sensor chip 1, a silicon substrate (silicon wafer) in which a large number of the diaphragms 2a and detection circuits are formed vertically and horizontally, and a glass substrate in which through holes 3a corresponding to the diaphragms 2a are formed in advance. Then, the bonded substrate is cut by using a dicing blade to divide the chip 1 into individual chips 1.
[0003]
By the way, when performing cutting (dicing) with a blade as described above, it is necessary to use a blade having a blade width (thickness) corresponding to the cutting thickness. On the other hand, the bonding substrate obtained by bonding the silicon substrate and the glass substrate described above is considerably thicker (generally about 2 to 3 mm) than the thickness of the silicon substrate (generally 300 to 600 μm). In order to cut, a blade having a large blade width (200 to 300 [mu] m) must be used. For this reason, there is a problem that the width of the scribe line of the silicon substrate, that is, the width of the invalid portion becomes large. As the chip 1 becomes smaller, there are cases where the ineffective area exceeds 10% of the entire silicon substrate.
[0004]
Therefore, in recent years, Japanese Patent Laid-Open No. 6-61346 (referred to as a first conventional example) and Japanese Patent Laid-Open No. 4-10554 (No. 1) are known as techniques for reducing the width of an ineffective portion in cutting a bonded substrate. 2), and those disclosed in Japanese Patent Application Laid-Open No. 8-32478 (referred to as a third conventional example). Among these, as shown in FIG. 8, in the first conventional example, after the silicon substrate 4 and the glass substrate 5 are joined, the silicon substrate 4 side is cut with a blade 6 having a small blade width, and then the glass substrate 5 side. Is cut with a blade 7 having a large blade width.
[0005]
Further, in the second conventional example, as shown in FIG. 9, a notch 8a is formed in advance at a position corresponding to the scribe line of the glass substrate 8, and then joined to the silicon substrate 4, and then the silicon substrate. 4 and the remaining part of the glass substrate 8 are cut at a time. In the third conventional example, as shown in FIG. 10, a notch 9a is formed in advance on the upper surface side of the glass substrate 9, and then joined to the silicon substrate 4, and then the silicon substrate 4 and the glass substrate 8 are joined. The remaining part of is cut. According to these, the blade 6 used for cutting the silicon substrate 4 can be made with a relatively small blade width, and the effective area can be expanded.
[0006]
However, in these first to third conventional examples, the shape of the pressure sensor chip 1 after cutting is such that the silicon chip 2 (silicon substrate 4) is the support base at the cut surface (side surface) portion as shown in FIG. Since it becomes a step shape (indicated by reference symbol a) protruding in an eave shape from 3, the following inconveniences were caused. That is, in recent years, as a surface protection structure of the pressure sensor chip 1, it has been considered that the entire chip 1 is covered with a gel, but the problem with this structure is how to suppress bubbles in the gel.
[0007]
However, if the step shape a as described above exists, the wraparound of the gel at the step portion becomes worse and a structure in which bubbles are easily generated is obtained. In the first and third conventional examples, although the cutting width (blade width) of the scribe line in the silicon substrate 4 can be reduced, the silicon chip 2 is removed from the support base 3 as shown in FIG. Since it protrudes, the circuit cannot be formed up to the end of the silicon chip 2, and eventually the protruding portion becomes a dead space and the problem of minimizing the ineffective portion is not solved. .
[0008]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a bonding that can prevent generation of a step shape in a cut surface portion while minimizing an ineffective portion of a scribe line of a semiconductor substrate. to provide a cutting how the substrate.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, a non-penetrating cut groove having a wedge-shaped cross section is formed at a position corresponding to the scribe line on the second substrate to be bonded to the semiconductor substrate by using a sandblast method. At the same time, each through hole is formed in advance, and after joining, the semiconductor substrate and the second substrate are simultaneously cut by dicing using a blade (invention of claim 1 ).
[0010]
According to this, when the bonded substrate is cut and divided into chips, the semiconductor substrate and the second substrate may be simultaneously cut by the blade so as to be connected to the cut groove along the scribe line. In this case, since the cut thickness is small, the blade width can be reduced. At this time, the cut groove has a wedge shape (forward taper shape), and the side surface of the cut chip is straight at the cut portion by the blade and is slightly inclined at the continuous cut groove portion. , No steps will occur.
[0011]
Therefore, according to the present invention, the width of the scribe line can be reduced and the ineffective portion of the semiconductor substrate can be reduced as much as possible. In the case of covering with a gel, there is an excellent effect that the generation of bubbles can be suppressed.
[0012]
Further, the second substrate, since a configuration to form a transmural throughbore simultaneously to form a switching inclusive groove, when performing the formation of the formation and notches of the through hole with respect to the second substrate in a separate process Compared to the above, the work can be performed more efficiently. Since the cut groove formed by the sand blasting method has a wedge shape (forward taper shape), it is suitable to use the sand blast method for forming the non-penetrating cut groove having the cross sectional wedge shape. .
[0013]
Furthermore, a non-penetrating cut groove can be formed in advance along the scribe line on the semiconductor substrate side (invention of claim 2 ). According to this, the cutting thickness by the blade after joining can be made thinner, the blade width can be further reduced, and the time required for the cutting operation can be shortened.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, with the first embodiment according to the present invention in the manufacture of the pressure sensor chip will be described with reference to FIGS. First, FIG. 2 shows the configuration of the pressure sensor chip 11 manufactured by the method of this embodiment. The pressure sensor chip 11 has a thickness of 300 to 600 μm, for example, and a 2.5 mm square to a 4.0 mm square. The silicon chip 12 having a certain size is supported by a glass support base 13 having a height of 2 to 3 mm, for example.
[0016]
The silicon chip 12 is formed with a thin diaphragm 12a at the center thereof, and although not shown, a detection circuit is formed on the upper surface side by, for example, four piezoresistors being bridge-connected. Has been. In addition, a through hole 13a having a circular cross section that communicates with the diaphragm 12a is formed at the center of the support base 13 so as to extend vertically. The through hole 13a has a gentle taper shape with a diameter decreasing toward the top. Further, the lower surface of the silicon chip 12 and the upper surface of the support base 13 are bonded by, for example, an anodic bonding method.
[0017]
Now, the pressure sensor chip 11 configured as described above is manufactured by cutting (dicing) the bonding substrate 14 as shown in FIG. 1 along the scribe line S using a blade (not shown). . Here, the configuration of the bonding substrate 14 according to the present embodiment will be described.
[0018]
The bonding substrate 14 is formed by bonding a silicon substrate (silicon wafer) 15 as a semiconductor substrate and a glass substrate 16 as a second substrate that plays an auxiliary role by an anodic bonding method in this case. The silicon substrate 15 is formed with a large number of the above-described diaphragms 12a and detection circuits arranged at predetermined intervals vertically and horizontally by a known process. The scribe lines S are set in a lattice form vertically and horizontally so as to divide the silicon substrate 15 into the silicon chips 12.
[0019]
On the other hand, the glass substrate 16 has a through hole 13a at a position corresponding to the center portion of each diaphragm 12a of the silicon substrate 15, and has a wedge-shaped cross section at a position corresponding to the scribe line S. Non-penetrating cut grooves 17 having a (V-shaped) shape are formed in a lattice shape vertically and horizontally. As will be described later, this cut groove 17 is several tens of μm from the surface opposite to the bonding surface (lower surface side in FIG. 1) to the bonding surface side (upper surface side in FIG. 1) of the glass substrate 16 by sandblasting. It is formed so as to leave a certain thickness. Further, the through hole 13 a is also formed simultaneously with the cut groove 17.
[0020]
Here, a method for manufacturing the bonding substrate 14 will be described with reference to FIGS. FIG. 3 sequentially shows the steps until the bonding substrate 14 is bonded. That is, first, as shown in FIG. 3A, a glass substrate 16 polished in a flat plate shape is prepared. Next, as shown in FIG. 3B, the glass substrate 16 is penetrated by sandblasting. A step of forming the hole 13a and the cut groove 17 is performed.
[0021]
In the processing by the sandblast method, as shown in FIG. 4, a resist mask 18 is provided on the surface of the glass substrate 16 (surface opposite to the bonding surface), and an opening 18 a is formed at a predetermined position in the resist mask 18. . In this case, as the opening 18a, a circular hole of about 1 mmφ, for example, is formed at the position where the through hole 13a is formed, and a lattice-like slit having a width of about several hundreds μm is formed at the position where the cut groove 17 is formed. . In FIG. 4, the glass substrate 16 is shown upside down with respect to FIGS.
[0022]
The glass substrate 16 is shaved by blowing air A mixed with abrasive grains from the tip of the nozzle 19 to the surface of the glass substrate 16 through the opening 18a. In this sandblasting method, the hole to be formed has a forward tapered shape with a predetermined angle. Therefore, by setting the optimal diameter dimension and width dimension of the opening 18a from the thickness and taper angle of the glass substrate 16 in advance, A through-hole 13a penetrating the substrate 16 and a wedge-shaped cut groove 17 having a predetermined thickness (about several tens of μm) can be formed on the bonding surface side of the glass substrate 16. At this time, since the cut groove 17 is in a non-penetrating state, it is a matter of course that the shape of the glass substrate 16 is maintained as an integral object.
[0023]
When the through hole 13a and the cut groove 17 are formed in the glass substrate 16 in this way, a step of polishing and flattening the surface (bonding surface) of the glass substrate 16 is performed as shown in FIG. Is done. Thereafter, although detailed explanation is omitted, a silicon substrate 15 in which the diaphragm 12a and the detection circuit are formed in a separate process is prepared, and the silicon substrate 15 and the glass substrate 16 are prepared as shown in FIG. And a step of joining the two by anodic bonding. Thus, the bonding substrate 14 as shown in FIG. 1 is formed.
[0024]
Then, the above-described bonding substrate 14 is cut (diced) using a blade (not shown), and the bonding substrate 14 is divided into individual pressure sensor chips 11 shown in FIG. In this cutting, the silicon substrate 15 and a part of the glass substrate 16 (the portion constituting the bottom of the cutting groove 17) are cut at the same time so as to be connected to the cutting groove 17 along the scribe line S. It is done by.
[0025]
At this time, the cutting thickness by the blade is obtained by adding the thickness of the silicon substrate 15 and the thickness of the thinnest portion (about several tens of μm) of the glass substrate 16 and is sufficiently small. Even if there is a situation where a blade having a blade width (thickness) corresponding to the thickness must be used, the blade width can be reduced (for example, about 30 μm used for cutting the silicon substrate 15). Thus, the width of the scribe line S of the substrate 15, that is, the width of the invalid portion can be reduced.
[0026]
Further, as shown in FIG. 2, the cut side surface of the pressure sensor chip 11 is straight at the cutting portion by the blade, and is continuously inclined at the cut groove 17 portion, and the silicon chip 12 is supported by the support base. Since it does not protrude in an eave shape from 13, a circuit can be formed up to the end of the silicon chip 12.
[0027]
Therefore, although not shown, as a surface protection structure of the pressure sensor chip 11, the entire chip 11 is recently covered with a gel. At this time, in the pressure sensor chip 11, there is no step as in the conventional example in the portion indicated by symbol b in FIG. 2 on the side surface, so that the gel wraps around when the entire chip 11 is covered with the gel Is performed well, and generation of bubbles can be suppressed.
[0028]
As described above, according to the present embodiment, the notch groove 17 having a wedge-shaped cross section is formed in advance by the sandblast method at a position corresponding to the scribe line S of the glass substrate 16, and after bonding to the silicon substrate 15, the silicon Since the substrate 15 and the thin portion of the glass substrate 16 are cut simultaneously, the ineffective portion of the scribe line S of the silicon substrate 15 can be made as small as possible, and the effective area can be expanded.
[0029]
Further, since no step is generated on the side surface of the pressure sensor chip 11, it is possible to effectively prevent the generation of bubbles when the entire chip 11 is covered with a gel, and troubles caused by the bubbles (cutting of bonding wires, etc.) are prevented. This can be prevented in advance. In particular, in the present embodiment, the through hole 13a is formed simultaneously with the formation of the cut groove 17 by the sandblasting method on the glass substrate 16, so that the through hole 13a is formed in a separate process (for example, an ultrasonic processing method). Compared with the case where it carries out in (4), the merit that efficient work can be performed can also be acquired.
[0030]
Figure 5 shows the structure of a bonded substrate 21 according to a second embodiment of the present invention. The bonding substrate 21 is also a second substrate in which a silicon substrate 22 as a semiconductor substrate on which the diaphragm 12a and the detection circuit are formed, and a non-penetrating cut groove 23 having a wedge-shaped cross section are formed in advance along the scribe line S. In this embodiment, a non-penetrating groove 25 is formed in advance along the scribe line S on the lower surface side of the silicon substrate 22. ing. According to this, the cutting thickness of the bonding substrate 21 by the blade can be further reduced, the blade width can be further reduced, and the time required for the cutting operation can be shortened.
[0031]
In the first embodiment, the through hole 13a is formed in the glass substrate 16 simultaneously with the formation of the cut groove 17 . FIG. 6 shows a bonded substrate 31 of a reference example, in which only a cut groove 33 is formed in a glass substrate 32 as a second substrate .
[0032]
In addition, the present invention is not limited to the above-described embodiments. For example, the present invention can be expanded and modified as follows, and can be appropriately modified and implemented within the scope not departing from the gist of the present invention. It is. That is, in the above embodiment, the pressure sensor chip is taken as a specific example. However, the present invention can be applied to other physical quantity sensor elements such as an acceleration sensor, and the present invention can be applied to all bonded substrates. it can.
[0033]
In this case, the second substrate is not limited to the glass substrate, but can be applied to various materials as long as it is a material capable of forming a cut groove having a wedge-shaped cross section, such as silicon, metal, or ceramic. The substrate bonding method is not limited to the anodic bonding method, and various bonding methods such as a low melting point glass method and a metal bonding method can be employed. The semiconductor substrate is not limited to a silicon substrate. Although the sandblasting method has been described here as a method for forming a wedge shape in the cross section, other methods such as an etching method may be used. Furthermore, it goes without saying that the thicknesses, width dimensions, and the like of the respective parts exemplified in the above embodiments are merely examples.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a bonding substrate according to a first embodiment of the present invention. FIG. 2 is a longitudinal sectional view showing a configuration of a pressure sensor chip. FIG. 4 is a view for explaining a method of forming a cut groove by sandblasting. FIG. 5 is a view corresponding to FIG. 1 showing a second embodiment of the present invention. FIG. 6 is a view showing a reference example . FIG. 7 is a longitudinal sectional view showing a configuration of a pressure sensor chip in a conventional example. FIG. 8 is a longitudinal sectional view showing a state of cutting a bonded substrate, showing a first conventional example. FIG. 10 is a longitudinal sectional view showing a bonding substrate (a) and a state (b) in which the bonding substrate (a) is cut. FIG. 10 is a diagram corresponding to FIG. 9 showing a third conventional example.
In the drawings, 11 is a pressure sensor chip (chip), 12 is a silicon chip, 13 is a support pedestal, 13a is a through hole, 14, 21 and 31 are bonded substrates, 15 and 22 are silicon substrates (semiconductor substrates), and 16 and 24. , 32 is a glass substrate (second substrate), 17, 23, 33 are cut grooves, 25 is a groove, and S is a scribe line.

Claims (2)

A bonding substrate formed by bonding a semiconductor substrate on which a large number of diaphragms and circuits are formed and a second substrate having a through-hole communicating with each diaphragm portion and having an auxiliary function is formed on the scribe line of the semiconductor substrate. A method for dividing into individual chips along
For the second substrate, using a sandblast method, a non-penetrating cut groove having a wedge-shaped cross section is formed in advance at a position corresponding to the scribe line on the surface opposite to the bonding surface , At the same time, each through hole is formed ,
A method for cutting a bonded substrate, wherein the semiconductor substrate and the second substrate are simultaneously cut by dicing using a blade. 2. The method for cutting a bonded substrate according to claim 1 , wherein a non-penetrating cut groove is formed in advance along a scribe line of the semiconductor substrate .

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