JP3307129B2 - Anodic bonding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anodic bonding apparatus for bonding a glass substrate to a semiconductor substrate having an electronic circuit or the like formed on one principal surface at a high temperature and a high voltage. The present invention relates to a technique for preventing a displacement of a glass substrate with respect to a semiconductor substrate.

[0002]

2. Description of the Related Art An anodic bonding apparatus for bonding a semiconductor substrate and a glass substrate at high temperature and high voltage has been known. Such a conventional anodic bonding apparatus is shown in FIG. In FIG. 12, the stage 8 has a built-in heater. The silicon substrate 1 as a semiconductor substrate is mounted on the stage 8. An electronic circuit and the like are formed on one main surface of the silicon substrate 1, and this one main surface is brought into contact with the stage 8 when mounting. An opening 6 is provided in a part of the silicon substrate 1. The opening 6 is formed using a micromachining technique. Specifically, the formation of the opening 6 is realized by, for example, chemical etching using an alkaline solution or mechanical processing.

[0003] The vacuum chuck 6 is for fixing the silicon substrate 1 to the stage 8 and communicates with a pipe 7. For example, a glass substrate 2 made of Pyrex glass is placed on the silicon substrate 1. Holder 4 is glass substrate 2
The vacuum chuck 3 for sucking the glass substrate 2 is provided on the surface of the holder 4. An electrode 5 is attached to the glass substrate 2 to apply a high voltage when bonding the glass substrate 2.

Next, the anodic bonding process will be described. The glass substrate 2 is held by the holder 4, transferred onto the silicon substrate 1, the silicon substrate 1 and the glass substrate 2 are aligned, and the glass substrate 2 is placed on the silicon substrate 1. After that, the holder 4 is removed, and the electrode 5 is placed on the glass substrate 2. At this time, the electrode 5 is placed quietly so as not to cause a positional shift with respect to the silicon substrate 1. Next, the stage 8 is heated to a bonding temperature suitable for bonding by a heater built in. Usually, the joining temperature is about 300 to 400 ° C. When the bonding temperature is reached, a bonding voltage is applied between the semiconductor substrate 1 and the glass substrate 2 via the electrode 5. At this time, the potential of the silicon substrate 1 is set higher than the potential of the glass substrate 2. When a bonding voltage is applied, a bonding current flows between the silicon substrate 1 and the glass substrate 2, and the silicon substrate 1 and the glass substrate 2 are directly bonded.

[0005]

In such a conventional anodic bonding apparatus, a larger electrode 5 is provided on the glass substrate 2 in order to reduce the bonding time. Before installing the electrode 5, the glass substrate 2
It is necessary to remove the holder 4 for use, and when the holder 4 is removed, the glass substrate 2 is not fixed, and the position between the glass substrate 2 and the silicon substrate 1 between the placement of the electrode 5 and the end of the bonding is completed. Gap is easy to occur. In addition, the adhesion between the glass substrate 2 and the silicon substrate 1 changes each time the process is started, and there is a possibility that bonding variations may occur.

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional problem, and an anodic bonding apparatus capable of preventing positional displacement when bonding a semiconductor substrate and a glass substrate and reducing bonding variations. The purpose is to provide.

[0007]

Therefore, in the anodic bonding apparatus according to the first aspect of the present invention, there is provided a semiconductor substrate and a stage for mounting a glass substrate which is positioned on the semiconductor substrate and positioned. An adsorption mechanism provided on the stage for adsorbing the semiconductor substrate under reduced pressure; a heater built in the stage for heating the semiconductor substrate and the glass substrate to a bonding temperature; and applying a high voltage between the semiconductor substrate and the glass substrate. And an electrode placed on a glass substrate when performing the above, in the anodic bonding apparatus provided with an opening through the substrate in a part of the semiconductor substrate, while the suction mechanism through the opening through the opening The glass substrate was adsorbed under reduced pressure.

In the anodic bonding apparatus according to the second aspect of the present invention, the suction mechanism includes a semiconductor substrate suction mechanism for vacuum-suctioning the semiconductor substrate and a glass substrate suction mechanism for vacuum-sucking the glass substrate, respectively. Configuration. In the anodic bonding apparatus according to the third aspect of the present invention, the suction mechanism includes a protruding means that can move up and down so as to push up the bonded semiconductor substrate and glass substrate from the stage surface.

In the anodic bonding apparatus according to a fourth aspect of the present invention, the projecting means is configured to have conductivity.
An urging means for urging the projecting means so as to contact the glass substrate is provided. In the anodic bonding apparatus according to the fifth aspect of the present invention, the urging means is made of an elastic body.

In the anodic bonding apparatus according to a sixth aspect of the present invention, the projecting means is a glass substrate suction chuck provided in a glass substrate suction mechanism.

[0011]

According to the structure of the anodic bonding apparatus according to the first aspect of the present invention, the semiconductor substrate is fixed on the stage by the suction mechanism, and the glass substrate is also provided on a part of the semiconductor substrate by the suction mechanism. Since it is adsorbed and fixed through the opening provided, it is possible to prevent displacement between when the electrode is placed and when bonding is completed, and when the glass substrate adheres to the semiconductor substrate. Therefore, the bonding variation is also reduced.

According to the configuration of the anodic bonding apparatus according to the second aspect of the present invention, since the glass substrate suction mechanism and the semiconductor substrate suction mechanism are provided independently, only the glass substrate is sucked without sucking the semiconductor substrate. Can be adsorbed, and damage to the surface of the semiconductor substrate caused by a difference in thermal expansion coefficient between the stage and the semiconductor substrate can be prevented. According to the configuration of the anodic bonding apparatus according to the third aspect of the present invention, the bonded semiconductor substrate and the glass substrate can be separated from the stage, and the surface of the semiconductor substrate generated when the bonded substrates are taken out of the stage is removed. Damage can be prevented.

According to the structure of the anodic bonding apparatus according to the fourth aspect of the present invention, the projecting means is urged by the urging means to come into contact with the glass substrate at a constant pressure, and the projecting means is electrically conductive. When a high voltage is applied, the stage and the glass substrate are kept at the same potential. Therefore, it is possible to prevent the semiconductor substrate from being damaged by electrostatic force generated when a high voltage is applied.

According to the structure of the anodic bonding apparatus according to the fifth aspect of the present invention, since the urging means is made of an elastic body, the projection means can be urged toward the glass substrate with a simple structure. . According to the configuration of the anodic bonding apparatus according to the sixth aspect of the present invention, since the projecting means is a glass suction chuck, the processes of sucking the glass substrate and separating the bonded substrates from the stage are performed by one suction chuck. It is possible to do with.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The same elements as those in FIG. 12 are denoted by the same reference numerals, and description thereof will be omitted. First, a first embodiment will be described. In FIG. 1 showing the anodic bonding apparatus of the first embodiment, the stage 8 is provided with a vacuum chuck 12 for sucking the glass substrate 2 toward the silicon substrate 1 which is a semiconductor substrate. Is in communication with Then, the silicon substrate 1 is placed on the stage 8 so that the opening 9 of the silicon substrate 1 and the vacuum chuck 12 are aligned, and the glass substrate 2 is further placed thereon.

The vacuum chucks 6, 12 and the pipe 7 correspond to a suction mechanism. FIG. 2 shows an automatic anodic bonding apparatus. In FIG. 2, a silicon substrate 1 is housed in a wafer case 21 as a wafer 22 on which an orientation flat is formed. The wafer 22 is transported on the rollers 23 to the wafer holder 24.

The wafer holder 24 is for placing the wafer 22 thereon for positioning the wafer 22, and rotates about the silicon holder rotating shaft 24a after the positioning.
As shown in FIG. 3A, which is a plan view of the wafer holder 24, and FIG. 3B, which is a cross-sectional view thereof, an alignment hole 31 for performing alignment with the wafer 22 is provided in the wafer holder 24.
A vacuum chuck 32 for vacuum-sucking 22 is provided, and on the surface of the wafer holder 24, an alignment mark area 33 on which an alignment mark is displayed is formed.

On the other hand, the glass substrate 2 is housed in a glass case 27 and is transported on a roller 25 to a glass holder 26. The glass holder 26 mounts the glass substrate 2 on the glass substrate 2 in order to align the glass substrate 2, and rotates about the glass holder rotating shaft 26a after the alignment.
Next, the anodic bonding process in this automatic apparatus will be described with reference to the flowchart of FIG.

Steps (denoted by "S" in the figure,
In the following, the same applies to 1).
The wafer 22 is taken out, transported to the wafer holder 24, and placed on the wafer holder 24 with the orientation flat of the wafer 22 aligned. In Step 2, the wafer 22 is vacuum-adsorbed and fixed on the wafer holder 24. In step 3, the position of the stage 8 and the position of the wafer holder 24 are aligned with the wafer holder 24 turned upside down.

In step 4, the wafer 22 is placed on the stage 8 and the vacuum suction of the wafer holder 24 is cut off. Then, the wafer holder 24 is returned to the original position. In step 5, take out the glass substrate 2 from the glass case 27,
It is conveyed to the glass holder 26 by the rotating shaft 25a. In step 6, the glass is vacuum-adsorbed and fixed to the glass holder 26.

In step 7, the glass holder 26 is turned over, and the vacuum chuck 12 for the glass substrate 2 and the silicon substrate 1
Is adjusted so that the opening 9 is aligned with the opening 9. In step 8, the wafer 22 is brought into contact with the glass substrate 2, the vacuum suction is cut off, and the glass substrate 2 is placed on the wafer 22. Then, the glass holder 26 is returned to the original position.

In step 9, the pressure is reduced through the pipe 7. Thus, the wafer 22 and the glass substrate 2 are vacuum-sucked by the vacuum chucks 6 and 12, respectively, and are firmly fixed, and the bonding surfaces of the glass substrate 2 and the wafer 22 are brought into close contact with each other in a reduced pressure state. In step 10, the electrode 5 is set on the glass substrate 2 in this state. Step 11
Then, cut off the vacuum suction.

In step 12, the heater incorporated in the stage 8 raises the bonding temperature to about 300 to 400 ° C.
In step 13, between the semiconductor substrate 1 and the glass substrate 2 via the electrode 5, the potential of the silicon substrate 1
A high voltage is applied in such a direction as to make the potential higher.
The junction voltage is usually on the order of 500-1500V. When a bonding voltage is applied, a bonding current flows between the silicon substrate 1 and the glass substrate 2, and the silicon substrate 1 and the glass substrate 2 are directly bonded.

In step 14, the system is cooled to room temperature. In step 15, the glass holder 26 is set and the glass substrate 2
Is vacuum-sucked to the bonded wafer 22. Then, the wafer 22 to which the glass substrate 2 has been bonded is taken out of the stage 8.
According to such a configuration, after alignment between the silicon substrate 1 and the glass substrate 2, the glass substrate 2 is vacuum-adsorbed through the opening 9 of the silicon substrate 1, so that bonding for bonding on the glass substrate 2 is performed. Even when the electrode 5 is placed, the glass substrate 2 can be placed on the silicon substrate 1 without causing displacement.

Further, the glass substrate 2 is made of the silicon substrate 1
Since the vacuum suction is performed through the upper opening 9, the bonding surfaces of the glass substrate 2 and the silicon substrate 1 are in a reduced pressure state, and the adhesion can be improved without using a complicated device such as a vacuum chamber. At the same time, the bonding pressure between the silicon substrate 1 and the glass substrate 2 can always be kept constant, so that bonding variation can be reduced, voids and the like after bonding can be prevented, and the anodic bonding yield can be improved.

Next, a second embodiment will be described. This is configured to prevent the occurrence of scratches and the like at the time of temperature rise on the surface of the silicon substrate in contact with the stage due to the difference in the coefficient of thermal expansion between the stage and the silicon substrate. FIG. 5 shows an anodic bonding apparatus according to a second embodiment.

In FIG. 5, a vacuum chuck 42 for fixing the silicon substrate 1 and a vacuum chuck 43 for the glass substrate 2 are independently formed on the stage 41.
Is installed in the center of the stage 41. The vacuum chucks 42 and 43 communicate with vacuum pipes 44 and 45, respectively. Next, the operation of the second embodiment will be described.

In the second embodiment, steps up to step 10 in FIG. 4 are the same as those in the first embodiment. In step 11, when the vacuum suction is cut off, the vacuum chuck 43 holds the glass substrate 2 while the vacuum chuck is held. The vacuum suction to the silicon substrate 1 by 42 is stopped. In this way, only the central portions of the silicon substrate 1 and the glass substrate 2 are fixed, and the peripheral portion of the silicon substrate 1 is free to expand. Then, a heater built in the stage 41 is energized to raise the temperature of the glass substrate 2 and the silicon substrate 1 to a bonding temperature of about 300 to 400 ° C.

According to such a configuration, the silicon substrate 1 and the glass substrate 2 are heated to the joining temperature while the glass substrate 2 is adsorbed at the center, so that even when the temperature is raised, the silicon substrate 1 and the glass substrate 2 are heated. While preventing misalignment with
The surface of the silicon substrate 1 in contact with the stage 41 due to the difference in the coefficient of thermal expansion between the stage 43 and the silicon substrate 1 is prevented from being scratched or the like. There is an advantage that anodic bonding can be performed without destroying peripheral circuits and the like.

In this embodiment, the vacuum chuck 43 is installed at the center of the stage 41. However, the installation position may be other than the center. However, it is more effective to install it in the center. Next, a third embodiment will be described. This is such that the silicon substrate and the glass substrate can be easily separated from the stage when the anodic bonding is completed.

FIG. 6 shows an anodic bonding apparatus according to a third embodiment.
In FIG. 6, the vacuum chuck 51 not only sucks the glass substrate 2 through the opening 9 formed in the silicon substrate 1 independently of the vacuum chuck 42 for fixing the silicon substrate 1, It is configured to move up and down in the figure until it protrudes. Also in the third embodiment, the vacuum chuck 51 is independent of the vacuum pipe 44 for adsorbing the silicon substrate 1 and the vacuum pipe 51 for adsorbing the glass substrate 2.
Communicates with 45.

Next, the operation will be described. In the third embodiment, after the glass substrate 2 is placed on the silicon substrate 1 and until the bonding is completed, up to step 14 in FIG.
Is brought into contact with the glass substrate 2 through the opening 9 of the silicon substrate 1, and the glass substrate 2 is vacuum-sucked. Step 15
When the glass substrate 2 and the silicon substrate 1 are taken out of the stage after the bonding is completed, the vacuum chuck 45
Push up. Thereby, one main surface of the silicon substrate 1 in contact with the stage 41 does not rub against the stage 41,
The stage 41 is a silicon substrate 1 to which the glass substrate 2 is bonded.
Pulled away from.

According to such a configuration, when the glass substrate 2 and the silicon substrate 1 after the bonding are taken out from the stage 41, the silicon substrate 1 is damaged on the surface of the silicon substrate due to the surface of the stage 41 rubbing. There is an advantage that the bonded glass substrate 2 and silicon substrate 1 can be taken out without any need. Next, a fourth embodiment will be described.

When a high voltage is applied between the silicon substrate and the glass substrate when there is a gap between the glass substrate and the silicon substrate as in the case of a semiconductor acceleration sensor, the device is attracted by electrostatic force. The structure is such that the silicon substrate is not broken. First, the structure of the semiconductor acceleration sensor will be described. 7 and 8 are a cross-sectional view and a plan view, respectively, showing an example of a semiconductor acceleration sensor.
The silicon substrate 61 and the glass substrate 62 are joined at the periphery of the sensor. The silicon substrate 61 has a beam 63 and a beam
A movable portion 64 supported by 63 and serving as a weight is formed.
Note that the beam 63 is usually about 10 μm. A groove 65 having a depth of about several μm is formed in the glass substrate 62 so as to correspond to the movable portion 64.
Are formed. In the groove 65, a conductor electrode 66 made of, for example, aluminum for electrostatically driving the movable portion 64 is formed, and an end portion thereof serves as a pad 67 for the conductor electrode 66. An opening 68 is provided on the silicon substrate 61 so as to face the pad 67. A GP for processing a sensor signal of the detected acceleration is provided on one main surface of the silicon substrate 61.
A circuit section 69 is formed. The pad 67 is connected to a wire 70 made of, for example, aluminum.
70 is wired to the GP circuit section 69 through the opening 68.

FIG. 9 is a plan view of a wafer. On a single wafer 71, a plurality of GP circuit sections 69 are arranged as indicated by oblique lines. In the semiconductor acceleration sensor having such a structure, acceleration is detected by electrostatically driving the movable portion 64 with the conductor electrode 66, and the sensor signal is subjected to signal processing in the GP circuit portion 69 and output.

Next, FIG. 10 is a view showing an anodic bonding apparatus used when anodic bonding such an acceleration sensor, and FIG. 11 is a partially enlarged view of FIG. In FIGS. 10 and 11, the vacuum chuck 72 that sucks the glass substrate 62 through the opening 68 formed in the silicon substrate 61 has conductivity. The stage 41 has an opening 65 of the silicon substrate 61.
The vacuum chuck 72 protrudes from the groove 73 so as to adsorb the glass substrate 62. In the groove 73, the vacuum chuck 72 is
An elastic body 71 for urging with a constant pressure is provided on the 62 side, and the urging force of the elastic body 71 brings the vacuum chuck 72 into contact with the pad 67,
The conductor electrode 66, the pad 67, and the stage 41 have the same potential.

The elastic body 71 is made of, for example, a spring, an air spring, rubber, or the like. Next, the operation will be described.
Until step 12 in FIG. 4, the same processing as in the first embodiment is performed. In step 13, a junction voltage is applied.
Note that the vacuum chuck 72 is urged by the urging force of the elastic body 71 and is in contact with the pad 67 on the glass substrate 62 at a constant pressure even if the vacuum chuck 72 does not perform vacuum suction.

Normally, the junction voltage is 500 to
Very high voltage of 1500V. This high voltage generates a very strong electrostatic force, and in a normal structure in which the movable portion 64 and the conductor electrode 66 are not held at the same potential, the movable portion 64
There is a possibility that the beam 63 supporting the movable portion 64 may be broken by being attracted to the movable portion 64. However, in this embodiment, even when the vacuum chuck 72 having conductivity is in contact with the pad 67 at a constant pressure even when vacuum suction is not performed, the vacuum chuck 72
Since the stage 41 and the pad 67 are electrically connected through the pad 67, the conductive electrode 66 and the silicon substrate are connected through the pad 67.
61, that is, the potential of the stage 41 and the movable portion 64 facing the conductor electrode 66 are equal potentials.
There is an advantage that the beam portion 63 supporting the beam can be joined without being destroyed by electrostatic force.

[0039]

As described above, according to the anodic bonding apparatus according to the first aspect of the present invention, it is possible to prevent displacement during bonding and reduce bonding variations. According to the anodic bonding apparatus according to the second aspect of the present invention, damage to the surface of the semiconductor substrate caused by the difference in the thermal expansion coefficient between the stage and the semiconductor substrate can be prevented.

According to the anodic bonding apparatus according to the third aspect of the present invention, it is possible to prevent the semiconductor substrate surface from being damaged when taking out both bonded substrates from the stage. According to the anodic bonding apparatus according to the fourth aspect of the present invention, it is possible to prevent damage to the semiconductor substrate due to electrostatic force generated when a high voltage is applied. According to the anodic bonding apparatus of the fifth aspect, the projection means can be urged toward the glass substrate by the elastic body.

According to the anodic bonding apparatus according to the sixth aspect of the present invention, the processes of sucking the glass substrate and separating the bonded substrates from the stage can be performed by one suction chuck.

[Brief description of the drawings]

FIG. 1 is a sectional view of an anodic bonding apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an automatic anodic bonding apparatus.

FIG. 3 is a view showing the silicon holder of FIG. 2;

FIG. 4 is a flowchart for explaining the steps in FIG. 2;

FIG. 5 is a sectional view of an anodic bonding apparatus according to a second embodiment.

FIG. 6 is a sectional view of an anodic bonding apparatus according to a third embodiment.

FIG. 7 is a sectional view of a semiconductor acceleration sensor according to a fourth embodiment.

FIG. 8 is a plan view of the same.

FIG. 9 is a plan view showing the arrangement of the sensor chips of FIG. 7 on a wafer.

FIG. 10 is a sectional view of an anodic bonding apparatus according to a fourth embodiment.

11 is a partially enlarged sectional view of FIG.

FIG. 12 is a cross-sectional view of a conventional anodic bonding apparatus.

[Explanation of symbols]

 1,61 Silicon substrate 2,62 Glass substrate 12,43,51,72 Vacuum chuck

Claims (6)

(57) [Claims] 1. A stage on which a semiconductor substrate, a glass substrate positioned on the semiconductor substrate and placed on the semiconductor substrate are mounted, an adsorption mechanism provided on the stage for adsorbing the semiconductor substrate under reduced pressure, and the stage Anodic bonding comprising: a heater which is built in and heats a semiconductor substrate and a glass substrate to a bonding temperature; and an electrode mounted on the glass substrate when a high voltage is applied between the semiconductor substrate and the glass substrate. An anodic bonding apparatus, wherein an opening penetrating through the substrate is provided in a part of the semiconductor substrate, and the glass substrate is vacuum-adsorbed through the opening by the suction mechanism. 2. The suction mechanism according to claim 1, wherein a semiconductor substrate suction mechanism for vacuum-suctioning the semiconductor substrate and a glass substrate suction mechanism for vacuum-sucking the glass substrate are provided independently of each other. The anodic bonding apparatus according to claim 1. 3. The anodic bonding according to claim 1, wherein said suction mechanism includes a projecting means which can move up and down so as to push up the bonded semiconductor substrate and glass substrate from the stage surface. apparatus. 4. The anode according to claim 3, wherein said protruding means is configured to have conductivity, and further comprises an urging means for urging said protruding means to come into contact with the glass substrate. Joining equipment. 5. The anodic bonding apparatus according to claim 4, wherein said urging means is made of an elastic body. 6. The anodic bonding apparatus according to claim 3, wherein said projecting means is a glass substrate suction chuck.