JP3577547B2 - Anodic bonding equipment - Google Patents

Description

[0001]
[Industrial applications]
According to the present invention, an anodic for bonding both wafers by stacking a silicon wafer and a glass wafer and applying a high voltage (0.5 to 1.5 KV) between the two wafers in a high temperature (300 to 400 ° C.) atmosphere. The present invention relates to a bonding device used for bonding.
[0002]
[Prior art]
In recent years, pressure sensors and acceleration sensors that use silicon wafers for miniaturization and high performance have been manufactured, and these sensors generally protect key parts such as sensor movable parts formed by etching silicon wafers. In order to form a structure cooperating with the movable part, a glass wafer having a required shape is bonded to a silicon wafer.
[0003]
The bonding between a silicon wafer and a glass wafer is generally performed by anodic bonding (anodic bonding), and a conventionally used anodic bonding apparatus has a configuration as shown in FIG. That is, the electrodes 13 and 14 are brought into contact with the silicon wafer 11 and the glass wafer 12, respectively, at substantially the center of the outer surfaces of the silicon wafer 11 and the glass wafer 12, and a voltage is applied between the pair of electrodes 13 and 14 so that the two wafers are connected. Anodic bonding was performed.
[0004]
[Problems to be solved by the invention]
When the silicon wafer 11 and the glass wafer 12 are joined by the anodic bonding apparatus shown in FIG. 2, interference fringes may be observed at the joint when the two wafers are overlapped. This is because the joint surface is not completely flat, for example, the joint surface has undulations, and the contact interval between the joint portions (the opposing interval of the joint portion, basically this is because of contact) is not uniform. When the anodic bonding is started in such a state, the bonding proceeds from a portion where the contact interval is narrow.
[0005]
At a part where the contact interval is wider than a certain value, bonding is difficult to proceed due to a decrease in electrostatic force.For example, an air layer remains at a part where the contact interval is wide surrounded by a part where the contact distance is narrow, and that part is further increased by the electrostatic force. In some cases, the parts were not attracted and the parts were not joined. FIG. 3 shows an example of this state in the case of bonding between a silicon wafer 11 and a glass wafer 12 which have not been processed at all. In FIG. 3, reference numeral 15 (hatched portion) indicates a portion where bonding has been completed, Numeral 16 indicates a defective bonding portion left in an island shape. Heretofore, such defective bonding due to the remaining air layer has been conventionally dealt with by performing bonding in a vacuum.
[0006]
On the other hand, when the wafer itself has a warp as shown in FIG. 4A, for example, if the silicon wafer 11 and the glass wafer 12 have a good flatness and no processing is performed, the electrostatic force is generated. It has been confirmed that a phenomenon in which the bonding gradually proceeds to the periphery because the portion acts more strongly on the narrow space and is attracted first, thereby narrowing the space around the space. As shown in (2), when steps or holes are formed on the bonding surface by etching or the like, the progress of bonding due to electrostatic force ends at the steps or holes, and there is a problem that further bonding cannot be performed. Was.
[0007]
SUMMARY OF THE INVENTION An object of the present invention is to provide an anodic bonding apparatus which eliminates the conventional drawbacks and can perform good bonding even on a wafer having steps or holes formed on the bonding surface without making the bonding atmosphere vacuum. It is in.
[0008]
[Means for Solving the Problems]
This invention anodic bonding apparatus for bonding the two wafers like silicon and glass, Ri Monodea that each part of the joint Ru provided pressurizing means for pressurizing the equalizing of all, the pressurizing means of their 2 a common electrode sheets of wafer-shaped silicon and glass superimposed are arranged, and a plurality of pressurizer being Taise' distributed evenly foremost superposed wafer-shaped silicon and the glass, and each of these pressurizer The pressurizing element is constituted by a plurality of coil springs which are interposed between the fixing portion and the biasing element and bias the pressing element toward the electrode.
[0009]
[Action]
The configured the invention as described above, the pressurization by the pressurizing means, the undulation or warping of the bonding surfaces can be corrected, the contact spacing of the joint each part can be evenly scratch.
[0010]
【Example】
An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a state in which a silicon wafer 11 and a glass wafer 12 to be bonded are attached to an anodic bonding apparatus according to the present invention. In this example, a plurality of concave portions 21 and 22 are formed on the respective bonding surfaces of the silicon wafer 11 and the glass wafer 12 so as to face each other, and portions other than the concave portions 21 and 22 are bonded.
[0011]
The bonding portions 23 and 24 corresponding to the silicon wafer 11 and the glass wafer 12 are positioned and overlapped, and the outer surface of the silicon wafer 11 is arranged on the common electrode 25 in contact with the common electrode 25. The common electrode 25 is a (+) electrode, and is connected to a (+) terminal of a power supply (not shown) by a wiring 26. The common electrode 25 is a plate-like body larger than the size of both wafers.
[0012]
The outer surface of the glass wafer 12, are distributed evenly one on its outer surface a plurality of pressurizer 27 is Taise'. Each pressing bit 27 in this example are distributed respectively evenly one is positioned at a position corresponding to the bonding portions 23 and 24 of the two wafers. Supporting shafts 28 are integrally formed on the surface of each pressing element 27 opposite to the surface in contact with the glass wafer 12, and the free ends of these supporting shafts 28 are formed through the fixing portion 29. The guide holes 31 are inserted through the respective guide holes 31.
[0013]
The fixing portion 29 is a plate-like body that faces substantially in parallel with the common electrode 25, and a coil spring 32 is interposed between the fixing portion 29 and each of the pressurizers 27, with their respective shaft centers being inserted through the support shaft 28. You. Each coil spring 32 acts to bias the pressurizer 27 toward the common electrode 25 side. In this example the pressurizer 27 (-) is obtained by a structure which also serves as an electrode, i.e., a plurality of (-) electrode has a structure that is distributed evenly one on the outer surface of the glass wafer 12. The support shaft 28 of each pressurizer 27 is connected to a (-) terminal of a power supply via a wiring 33.
[0014]
The facing distance between the common electrode 25 and the fixing portion 29 is adjustable, and the peripheral portions are connected to each other. That is, as shown in FIG. 1, mounting holes 34 and 35 facing each other are formed in the fixing portion 29 and the common electrode 25, respectively, and the bolt 36 is inserted through the mounting hole 34 through the insulating spacer 37. Furthermore, the common electrode 25 and the fixing part 29 are connected via the bolt 36 by inserting the tip into the mounting hole 35 and screwing the nut 38. The connection by the bolts 36 may be, for example, four points at 90 ° intervals on the circumference when the common electrode 25 and the fixing part 29 are disc-shaped, or four corners when they are rectangular.
[0015]
The installation of the silicon wafer 11 and the glass wafer 12 to be bonded on the common electrode 25 can be performed by loosening the screw of the nut 38 to widen the gap between the common electrode 25 and the fixing portion 29. If the screwing of the nut 38 is advanced after both the wafers are set, the distance between the common electrode 25 and the fixing portion 29 becomes narrower, and a load is applied to each pressurizer 27 by the elastic force of the coil spring 32 so that the two wafers are loaded. Are brought into close contact with each other, so that the joints 23 and 24 can be pressurized.
[0016]
By increasing the pressure until the interference fringes are no longer observed at the joints 23 and 24, the contact interval between the joints 23 and 24 can be narrowed and uniform. If anodic bonding is performed in this state, All the joints 23 and 24 are joined well. The load applied to the pressurizing element 27 is, for example, 2 to 3N.
[0017]
【The invention's effect】
As described above, by each unit of the joint anodic bonding apparatus according to the present invention provided with a pressurizing means for pressurizing the equalizing one, junction each section to correct the waviness or warping of the joint each section narrowing the contact gap, it is possible to do one uniform one without a vacuum bonding atmosphere, can also be well bonded to the bonding portion in the wafer is stepped or holes are formed on the bonding surface .
[0018]
In the conventional anodic bonding apparatus shown in FIG. 2, since a pair of electrodes are brought into contact with the central portion of the wafer, there is a problem that the electric field at the outer peripheral portion of the wafer decreases due to a voltage drop. as in the embodiment according to the present invention shown in FIG. 1, assuming that the pressurizer also serves as an electrode, are distributed a plurality of electrodes evenly one on one of the outer side surface of another of the two wafers to be joined, the other if the other electrode on the outer surface so as to entirely Taise', since the electric field between the wafer at each joint can be evenly one, i.e. it is possible to eliminate the electric field shortage of the wafer outer peripheral portion, it Bonding failure due to the above can be significantly reduced.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an embodiment of an anodic bonding apparatus according to the present invention.
FIG. 2 is a diagram for explaining a configuration of a conventional anodic bonding apparatus.
FIG. 3 is a plan view showing a bonding failure by a conventional anodic bonding apparatus.
FIG. 4A is a diagram for explaining the progress of joining, and FIG. 4B is a diagram for explaining that the progress of joining is stopped.
[Explanation of symbols]
Reference Signs List 11 silicon wafer 12 glass wafer 23, 24 joint 25 common electrode 27 pressurizer 29 fixing part 32 coil spring

Claims (1)

In an anodic bonding apparatus for bonding two wafers of silicon and glass,
Pressurizing means for pressurizing the respective parts of the joint evenly one is provided,
The pressurizing means includes a common electrode on which the two superposed wafer-shaped silicon and glass are arranged, and a plurality of pressurizers uniformly distributed and contacted on the superposed wafer-shaped silicon and glass. And a plurality of coil springs interposed between each of the pressurizing elements and the fixed part, and biasing the pressing element toward the electrode .

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