JP3324418B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device having a microstructure, and more particularly to a technique for protecting a pad electrode during dicing.

[0002]

2. Description of the Related Art As a conventional semiconductor device, there is, for example, a semiconductor acceleration sensor described in Japanese Patent Application No. 7-337353. FIG. 5 is a sectional view of the conventional example.

In FIG. 5, reference numeral 1 denotes a silicon substrate.
A weight 2 for acceleration detection and a beam 3 for supporting the weight 2 are formed on the silicon substrate 1 by anisotropic etching, and are supported by a surrounding frame 6. Further, a pad electrode 7 for taking out a detection output such as acceleration to the outside is formed on the silicon substrate 1.

Further, the cap glass substrate 4 has a weight 2
The base glass substrate 5 also has a dent at a portion facing the weight 2 in the same manner. The cap glass substrate 4 and the pedestal glass substrate 5 are anodically bonded to the frame 6 of the silicon substrate 1 and have a sandwich structure. Further, the end of the cap glass substrate 4 corresponding to the position of the pad electrode 7 has been removed, so that the pad electrode 7 is exposed and is formed in a state in which wire bonding is possible.

In such a conventional semiconductor device, dicing is generally used to remove the opening of the cap glass substrate 4 just above the pad electrode 7, and it is necessary to cut out the entire thickness of the glass just above the pad electrode portion. It is. Therefore, a space is created in a part of the cap glass substrate 4 facing the pad electrode 7 so that the tip of the dicing blade does not contact the pad electrode 7, and the structure is such that the tip of the blade operates in the space. I have.

[0006]

However, in the opening step just above the pad electrode portion, even if the tip of the dicing blade does not contact the pad electrode, the dicing blade passes just above the pad electrode. There is a problem that the glass fragments are accelerated by the rotation of the blade and stick to or damage the pad electrode.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a method of manufacturing a semiconductor device which prevents a failure due to scattering of glass fragments to a pad electrode during dicing. .

[0008]

Means for Solving the Problems In order to achieve the above object, the present invention is configured as described in the claims. That is, in the present invention, a groove that penetrates from one end to the other end of the wafer of the cap substrate is provided in advance in a portion corresponding to the position of the pad electrode on the wafer of the cap substrate, and after the wafer bonding step, the groove is formed. A protective material is injected, and then the dicing cut is performed.

With the above-mentioned structure, even if glass cutting fragments are scattered during dicing, the protective material covering the pad electrode traps and damages the cutting fragments before reaching the pad electrode. Can be prevented. Further, in the dicing for dividing the semiconductor device into the final stage, the contamination of the pad electrode mainly by silicon dust can be prevented for the same reason.

The protective material may be a water-repellent substance such as a resist, or a water-soluble solvent for cleaning semiconductors. Note that the above protective material is removed after the dicing step is completed.

[0011]

According to the present invention, since the protective material provided on the pad electrode blocks the glass fragments during dicing, the pad electrode can be protected and the dicing yield can be improved. Further, in the dicing for dividing the semiconductor device into the final stage, the contamination of the pad electrode by silicon dust can be prevented for the same reason. Further, according to the manufacturing method of the present invention, simultaneously with the injection of the protective material, it becomes possible to determine the sealing state of the internal region to be sealed by the injected state of the protective material. There is also an effect that a sealing test is not required.

[0012]

1 and 2 show a first embodiment of the present invention.
FIG. 3 is a diagram showing an embodiment of the present invention, showing a case where the present invention is applied to a method for manufacturing a semiconductor acceleration sensor. First, FIG. 1 is a plan view and a cross-sectional view of each wafer before bonding.
1A shows a silicon substrate wafer, FIG. 1B shows a cap glass substrate wafer, and FIG. 1C shows a pedestal glass substrate wafer. Each component corresponding to a plurality of semiconductor elements (in this case, an acceleration sensor) is formed on each wafer. The above glass substrate is made of, for example, Pyrex glass.

In FIG. 1A, 8 is a silicon substrate wafer as a semiconductor substrate, 9 is a pad electrode, 10 is a weight for detecting acceleration, and 11 is a beam for supporting the weight.
The weights 10 and the beams 11 are formed by anisotropically etching the silicon substrate 8 from the back surface (the surface opposite to the surface on which the pad electrodes 9 are provided).

In FIG. 1B, reference numeral 12 denotes a cap glass substrate wafer. The cap glass substrate wafer 12 has a groove 14 for forming a space for allowing the weight portion 10 to be displaceable, and a cap glass substrate wafer 1.
The groove 15 penetrating from one end to the other end of 2 is selectively formed in advance by etching using hydrofluoric acid or the like. The groove 15 is formed in a region where the tip of the dicing blade passes. At this time, it is necessary that the groove 14 is formed at a position corresponding to the displacement area of the weight portion 10 formed on the silicon substrate wafer 8 and the groove 15 is formed at a position corresponding to the pad electrode 9.

In FIG. 1C, reference numeral 13 denotes a pedestal glass substrate wafer. This pedestal glass substrate wafer 13
First, a groove 16 forming a space for allowing the weight portion 10 to be displaceable is selectively formed in advance by etching using hydrofluoric acid or the like.

Next, FIG. 2 is a sectional view showing a manufacturing process. First, FIG. 2A shows a state where the silicon substrate wafer 8 and the cap glass substrate wafer 12 are anodically bonded. At this time, the cap glass substrate wafer 12 is turned upside down from the state shown in FIG. That is, one main surface of the silicon substrate wafer 8 on which the pad electrode 9 is formed and one main surface of the cap glass substrate wafer 12 on which the groove 14 and the groove 15 are provided are aligned and joined. At this time, the groove 14 is overlapped so as to match the position of the weight portion 10 and the beam 11, and the groove 15 is overlapped so as to match the position of the pad electrode 9.

Next, FIG. 2 (b) shows that the pedestal glass substrate wafer 13 is anodically bonded to the wafer in which the silicon substrate wafer 8 and the cap glass substrate wafer 12 are bonded in the above (a), 17 has been filled. Silicon substrate wafer 8 and pedestal glass substrate wafer 13
At the time of joining, the groove 16 is overlapped and joined so that the groove 16 matches the position of the weight portion 10 and the beam 11. The bonding of the silicon substrate wafer 8, the cap glass substrate wafer 12, and the pedestal glass substrate wafer 13 may be performed simultaneously by stacking three wafers.

The protection material 17 is injected through a groove 15 penetrating from one end of the cap glass substrate wafer 12 to the other end. As a method for injecting the protective material 17, it is effective, for example, to immerse the wafer in a liquid protective material under a suitable low pressure under a so-called vacuum for a certain period of time. A groove 15 is previously formed in the cap glass substrate wafer 12 at a position corresponding to the pad electrode 9 of the silicon substrate wafer 8, and the groove 15 penetrates from one end of the cap glass substrate wafer 12 to the other end. From the drop in vacuum pressure,
As time passes, the injection of the protective material proceeds from the end face to the center. As the protective material 17, for example, a water-repellent substance such as a resist may be used, or a water-soluble solvent for cleaning a semiconductor may be used.

Next, FIG. 2C shows a state in which a dicing step for forming an opening of the pad electrode has been performed. After injecting the protective material 17, the process proceeds to an opening process for exposing the pad electrode 9 through a drying process. As the opening method, cutting by a dicing device is generally used. Since the cap glass substrate wafer 12 immediately above the pad electrode 9 has already been grooved from one end to be diced to the other end, the dicing blade is operated along the groove. At this time, it is required that the blade height be set without contact with the pad electrode 9 and without leaving the cap glass substrate wafer 12 uncut.
Set so that the blade tip runs in the space of.

Next, FIG. 2D shows a state in which the three wafers are bonded and the pad electrodes 9 are exposed as described above, and each wafer of the semiconductor device is cut. This chip cutting step is also performed by dicing. Next, FIG. 2E is a diagram showing a semiconductor acceleration sensor chip completed after the above cutting.

After the dicing for cutting into chips as shown in FIG. 2D, a step of removing the protective material 17 is performed. In this step, when the protective material 17 is a resist, it may be washed with an organic solvent for washing such as acetone. When the protective material 17 is a water-soluble detergent for semiconductors, it may be simply washed with water. Note that the protective material removing step may be performed after the dicing for exposing the pad electrode 9 in FIG.

Next, the operation will be described. When the cutout opening is performed by dicing in a state where the protective material 17 is not covered on the pad electrode 9, the cut cap glass fragments accelerate to the rotation of the blade because the pad electrode 9 is located right below the blade. As a result, there were many cases where the pad electrode 9 was directly hit and damaged. In particular,
The closer the height of the blade tip is to the pad electrode 9, the greater the tendency becomes, and it is also difficult to set the blade height. However, in the present invention, the protection material 17 covering the pad electrode 9 can be easily injected, and even if the broken glass fragments are scattered, the pad electrode 9 can be injected.
The overlying protective material 17 traps the cutting debris before reaching the electrode to prevent damage.

Further, in the final dicing for dicing into semiconductor chips, pad contamination mainly due to silicon dust can be prevented for the same reason. That is,
During the cutting of the semiconductor chip subsequent to the cutting of the opening, the protective material is trapped even when the silicon pieces are largely floating, and can be washed away in the subsequent protective material removing step.

Further, for example, the weight portion 1 is formed by anodic bonding or the like.
According to the manufacturing method of the present invention, in a semiconductor device that needs to seal the 0, the beam 11 and the like with a cap substrate, a sealing test after cutting the semiconductor chip is not required. In other words, if the area other than the sealing area is separated from the sealing area at the same position as the arrangement of the pad electrodes on the silicon substrate wafer and has a groove penetrating from the edge of the substrate wafer to the other end, the groove is cut When the protective material is injected into the portion under vacuum, if the sealing is insufficient, the protective material permeates into the region to be sealed, resulting in a defective product, so it can be determined that the sealing is not complete. On the other hand, if the sealing is completed, the above is not the case, and it is also possible to determine whether the sealing is good or not at the same time when the protective material is injected.

FIGS. 3 and 4 show a second embodiment of the present invention. The present invention relates to a method of manufacturing a semiconductor device using a surface micromachining technique which requires a cap material. Shows the case where is applied.

First, FIG. 3 is a plan view and a sectional view of each wafer before bonding, and FIG.
FIG. 3B shows a cap glass substrate wafer. FIG.
1A, reference numeral 18 denotes a silicon substrate wafer; 19, a micromachine movable portion formed on the surface of the silicon substrate wafer 18; and 20, a pad electrode.

The above-mentioned micromachine movable section 19
Are formed by processing such as etching from the surface of the silicon substrate wafer 18 (the surface on which the pad electrodes 20 are formed).

In FIG. 3B, reference numeral 22 denotes a cap glass substrate wafer, and reference numeral 21 denotes a silicon substrate wafer 18 without touching a surface processed portion (micromachine movable portion).
Further, a groove 23 for sealing a surface processed portion is a groove penetrating from one end of the cap glass substrate wafer 22 to the other end. The groove 23 is provided at a position corresponding to the position of the pad electrode 20. In FIG. 3, the basic configuration other than the above is the same as the description of FIGS. 1 and 2.

FIG. 4 is a sectional view showing a manufacturing process. First, FIG. 4A shows a groove 2 penetrating from one end to the other end of the cap glass substrate wafer 22 after the silicon substrate wafer 18 and the cap glass substrate wafer 22 are anodically bonded.
FIG. 3 is a cross-sectional view showing a state where a protective material 24 is filled in 3. The joining step and the step of filling the protective material are the same as those in FIG.

FIG. 4B shows a state in which a dicing step for forming an opening for exposing the pad electrode 20 has been performed. FIG. 4C shows a state in which a dicing step for cutting into semiconductor chips has been performed. FIG. 4 (d)
FIG. 3 is a schematic view showing a semiconductor chip completed after cutting.
Details of each of the above steps are the same as those in FIG.

The operation will be described below. In a semiconductor device in which a movable portion is formed by processing a surface portion of a silicon substrate by a micromachining technique, a processed portion is particularly fine. In mounting a semiconductor device, it is common to completely protect the semiconductor chip from moisture, for example, by using a can package or the like. If mounted in a state, cost reduction can be achieved. However, in this case, as described above, in the method of extracting the pad electrode, the method of cutting the opening for each wafer substrate has a problem such as damage to the electrode, which has been difficult to realize. However, according to the manufacturing method of the present invention, by cutting the opening for extracting the electrode, without damaging the electrode, and further completely sealing the surface processed portion other than the electrode portion with cap glass, during dicing, There is no mixing of cuttings. Therefore, the dicing yield, the reliability of the semiconductor device, the manufacturing process can be simplified, and the manufacturing cost can be reduced at the same time.

[Brief description of the drawings]

1A and 1B are a plan view and a cross-sectional view of each wafer before bonding in a first embodiment of the present invention, wherein FIG. 1A is a silicon substrate wafer, FIG. 1B is a cap glass substrate wafer,
(C) is a pedestal glass substrate wafer.

FIG. 2 is a sectional view showing a manufacturing process according to the first embodiment of the present invention.

3A and 3B are a plan view and a cross-sectional view of each wafer before bonding according to a second embodiment of the present invention, wherein FIG. 3A is a silicon substrate wafer, and FIG. 3B is a cap glass substrate wafer.

FIG. 4 is a sectional view showing a manufacturing process according to a second embodiment of the present invention.

FIG. 5 is a sectional view of a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Silicon substrate 2 ... Weight part 3 ... Beam 4 ... Cap glass substrate which has a dent facing a weight part 5 ... Pedestal glass substrate which has a dent facing a weight part 6 ... Frame which supports a silicon substrate 7 ... Pad electrode 8 ... Silicon substrate wafer 9 ... Pad electrode 10 ... Weight 11 ... Beam 12 ... Cap glass substrate wafer 13 ... Pedestal glass substrate wafer 14 ... Groove for securing weight part stroke on the cap substrate wafer side 15 ... End face of cap glass substrate wafer 16: Groove for securing weight part stroke on pedestal glass substrate wafer side 17: Protective material 18: Silicon substrate wafer 19: Micro machine processing part 20: Pad electrode 21: Silicon surface processing part sealing Groove 22: Cap glass substrate wafer 23: Penetration from end to end of cap glass substrate wafer Groove 24 ... Protective material

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hideo Muroru 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. (56) References JP-A-5-95046 (JP, A) JP-A-8- 254438 (JP, A) JP-A-5-41148 (JP, A) JP-A-5-203669 (JP, A) JP-A-9-326371 (JP, A) JP-A-9-232596 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/301 H01L 49/00 H01L 29/84 G01P 15/12 B81C 1/00 B81B 3/00

Claims (6)

(57) [Claims] A step of joining a wafer of a semiconductor substrate on which at least a movable portion and a pad electrode are formed and a wafer of a cap substrate, and dicing and cutting a portion of the wafer of the cap substrate corresponding to the position of the pad electrode. Exposing the pad electrode by a method of manufacturing a semiconductor device, comprising: a groove previously penetrating from one end of the wafer of the cap substrate to the other end in a portion corresponding to the position of the pad electrode on the wafer of the cap substrate. Wherein a protective material is injected into the groove after the joining step, and thereafter the dicing cut is performed. 2. The semiconductor substrate according to claim 1, wherein a movable portion is formed by anisotropic etching from the back surface of the substrate, and a pedestal substrate is bonded to the back surface of the semiconductor substrate. The manufacturing method of the semiconductor device described in the above. 3. The method according to claim 1, wherein a movable portion is formed on the semiconductor substrate by processing only from a front surface side of the substrate. 4. The method for manufacturing a semiconductor device according to claim 1, wherein the injection of the protective material is performed by evacuation. 5. The method of manufacturing a semiconductor device according to claim 1, wherein said cap substrate is made of Pyrex glass, and each wafer is bonded by anodic bonding. 6. The method according to claim 1, wherein the protective material is a resist.