JP2010034445A - Automatic wafer bonding device, and automatic wafer bonding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic wafer bonding device and an automatic wafer bonding method that reduce bonding void defects. <P>SOLUTION: The automatic wafer bonding device includes: a stage for holding a first wafer; a pressing means of pressing an outer peripheral portion of a second wafer mounted in a state wherein bonding does not start against the first wafer; and an air inclusion preventing means disposed at a position opposite a pressing position by the pressing means with the first wafer and second wafer interposed, and preventing air from being included between both the wafers when the first wafer and second wafer begin to be bonded by being pressed by the pressing means and the bonding is carried on from the pressing position to the opposite position and completed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an automatic wafer bonding apparatus and an automatic wafer bonding method for manufacturing a semiconductor wafer such as an SOI wafer.

Conventionally, SOI (Silicon On Insulator) wafers have attracted attention as semiconductor device substrates due to their high IC integration, high performance, and excellent radiation resistance. Typical methods for manufacturing this SOI wafer include a SIMOX (Separation by IMplanted OXygen) method and a bonding method. The SIMOX method is a method of manufacturing an SOI wafer by ion-implanting oxygen with high energy into a silicon single crystal wafer and bonding it to silicon by a subsequent heat treatment to form an oxide film (SiO ₂ ) within a few μm from the wafer surface. It is. On the other hand, the bonding method involves bonding a silicon wafer with an oxide film (SiO ₂ ) on the surface and another silicon wafer with heat or pressure, and then grinding and removing the other silicon wafer to a predetermined thickness. This is a method of manufacturing an SOI wafer.

Among these manufacturing methods, the bonding method has better crystallinity in the device fabrication region than other methods, and the Si-SiO ₂ interface is stable by using the interface on the thermally oxidized side on the device side. It is a method that is widely used because it has advantages such as low cost of equipment for mass production.

  In Patent Document 1, a semiconductor wafer laminating method in which at least one of the first wafer and the second wafer is curved and deformed, and the bonding surfaces thereof are overlapped with each other, a second point of the peripheral portion of the first wafer and a second point. Joining from one point at the periphery of the wafer is used as the bonding start point, and the opposite electrode point on the opposite side of this bonding start point across the center point of the bonding surface of these wafers is used as the bonding end point. A semiconductor wafer laminating method is disclosed in which joining is sequentially advanced toward an end point.

JP-A-5-275300

  However, as shown in FIG. 1, in the conventional bonding of SOI wafers as disclosed in Patent Document 1, the bonding is started from the bonding pressing position by external force, and the bonding propagates to the entire surface of the wafer and expands. (In FIG. 1, it propagates from the left to the right of the wafer), however, the surface condition and shape of the wafer have an effect, and air is enclosed in the terminal portion, which is the main cause of void defects. . Since this bonding void defect affects the hydrophilicity of the two wafer surfaces and the minute surface flatness, it is difficult to improve and control the wafer processing accuracy. In addition, when this bonding void defect occurs, it peels again and is bonded again, which is a problem that greatly contributes to SOI wafer productivity.

  An object of the present invention is to provide an automatic wafer bonding apparatus and an automatic wafer bonding method that can reduce bonding void defects.

The gist of the present invention is as follows.
(1) A stage for holding the first wafer, pressing means for pressing the outer peripheral portion of the second wafer placed on the first wafer in a state where bonding is not started, the first wafer, and the second wafer The wafer is sandwiched between the pressing position by the pressing means and the opposing position, and the bonding of the first wafer and the second wafer is started by pressing by the pressing means, from the pressing position toward the opposing position. An automatic wafer bonding apparatus comprising: air sealing prevention means for preventing air sealing between the wafers when the bonding is completed and completed.

  (2) The wafer automatic bonding apparatus according to the above (1), further comprising a shift correcting unit that is provided around the stage and corrects a shift between the first wafer and the second wafer.

  (3) The wafer automatic bonding apparatus according to (2), wherein the deviation correcting means includes an orientation flat / notch guide and a pair of pin guides.

  (4) The wafer automatic bonding apparatus according to (1), (2) or (3), wherein the air sealing prevention means further includes a control means for extracting air so as not to affect the bonding propagation state.

  (5) The air sealing prevention means includes an insertion jig inserted between the first wafer and the second wafer and at one or more outer peripheral portions of the first wafer and the second wafer. The wafer automatic bonding apparatus according to any one of (1) to (4) above.

(6) The stage has a suction holding mechanism for holding the first wafer,
The air sealing prevention means vacuum-sucks at least one of a surface opposite to the bonding surface of the first wafer and a surface opposite to the bonding surface of the second wafer to forcibly The wafer automatic bonding apparatus according to any one of (1) to (4), wherein one wafer and / or the second wafer is deformed.

(7) The stage has a suction holding mechanism for holding the first wafer,
The air sealing prevention means has a bonding inhibition mechanism by compressed air injection between the first wafer and the second wafer and at one or more outer peripheral portions of the first wafer and the second wafer. The wafer automatic bonding apparatus according to any one of (1) to (4).

  (8) The bonding of the first wafer and the second wafer is started by pressing the outer peripheral portion of the second wafer placed on the first wafer held on the stage without starting the bonding. Then, with the first wafer and the second wafer sandwiched from the pressing position, the pasting is advanced toward the position opposite to the pressing position, and air sealing prevention means provided in advance at the facing position And a wafer automatic bonding method characterized by preventing air sealing between the two wafers when the bonding is completed.

  The wafer automatic bonding apparatus and wafer automatic bonding method of the present invention set the pressing position by the pressing means to the outer peripheral portion of the wafer, and the bonding end position propagating therefrom is the position opposite to the wafer bonding start position. By confining to air, the voids of bonded wafers are reduced by automatically releasing the collected air to the outside of the wafer by air sealing prevention means so that voids and distortion do not occur. , Production yield can be improved. In addition, by reducing void defects, surface defects caused by peeling when void defects occur, and deterioration in bonding quality such as deterioration of the roughness of the bonding surface due to re-cleaning are improved and stabilized, and correction work is eliminated. Productivity can be improved.

  Next, an embodiment of the automatic wafer bonding apparatus of the present invention will be described with reference to the drawings. FIG. 2 is a schematic diagram showing the wafer automatic bonding apparatus according to the first embodiment of the present invention. 3 and 4 are schematic views showing cross sections of the wafer automatic bonding apparatus according to the second and third embodiments of the present invention, respectively.

  As shown in FIG. 2, the wafer automatic bonding apparatus 100 according to the first embodiment of the present invention is mounted on the stage 2 that holds the first wafer 1 and the first wafer 1 in a state where bonding does not start. A pressing means 4 for pressing the outer peripheral portion of the second wafer 3 placed thereon, and the pressing means 4 provided at a position opposite to the pressing position by the pressing means 4 with the first wafer 1 and the second wafer 3 interposed therebetween. Bonding of the first wafer 1 and the second wafer 3 is started by pressing by, and the bonding proceeds from the pressing position toward the facing position, and between the wafers 1 and 3 when completed. By adopting such a configuration, the void defect of the bonded wafer can be reduced.

  The first wafer 1 and the second wafer 3 have a roll-off shape in which the outer peripheral portion of the wafer is warped toward the opposite side of the mirror surface as compared with the central portion, or is warped toward the mirror surface side as compared with the central portion. Any shape such as a rolled-up shape can be used. Examples of the pressing means 4 include a weight, a pressurizing device having a pressure control mechanism, and a pressing device using a cylinder.

  The wafer automatic bonding apparatus 100 according to the present invention preferably further includes a displacement correcting means 6 provided around the stage 2 and for correcting the displacement between the first wafer 1 and the second wafer 3. The second wafer 3 can be naturally dropped on the first wafer 1, but when there is a deviation between the first wafer 1 and the second wafer 3, the void defect is sufficiently reduced. It is because it cannot be done.

  The displacement correcting means 6 preferably has an orientation flat / notch guide 6a and a pair of pin guides 6b. This is to ensure uniformity between wafers by aligning the plane orientation.

  Furthermore, although not shown in FIG. 2, it is preferable that the air encapsulating prevention means 5 further includes a control means for extracting air so as not to affect the bonding propagation state. It has been found that when bonding propagation is stopped halfway, distortion may occur at the boundary portion. Therefore, in order to prevent the operation of the air sealing prevention means 5 from stopping the bonding propagation, a control means for removing air so as not to affect the bonding propagation state is provided. In addition, as this control means, a timer is mentioned, for example, It is preferable to start the process which extracts air 1-2 seconds after a weight gets down.

  The air sealing prevention means 5 is inserted between the first wafer 1 and the second wafer 3 and at one or more outer peripheral portions of the first wafer 1 and the second wafer 3. It is preferable to have an insertion jig 5A. The insertion jig 5A may have any shape as long as it is adjusted so as to be in contact with the chamfered portion of the wafer that does not contact the mirror surface of both wafers 1 and 3, for example, as shown in FIG. It can be set as the nail-like member 5A. FIG. 2 shows an example in which the claw-like member 5A is provided on the orientation flat / notch guide 6a. However, it is only necessary that the claw-like member 5A is provided at a position opposite to the pressing position by the pressing means 4.

  FIGS. 3A and 3B show wafer automatic bonding apparatuses 200a and 200b according to the second embodiment of the present invention, respectively, and the stage 2 holds the first wafer 1. An air holding prevention means 5B is provided on the side opposite to the bonding surface of the first wafer 1 and the bonding surface of the second wafer 3. It is preferable to vacuum-suck at least one of the surfaces and forcibly deform the first wafer 1 and / or the second wafer 3. 3A shows an example in which only the first wafer 1 is deformed, and FIG. 3B shows an example in which both the first wafer 1 and the second wafer 3 are deformed. It is. Since each wafer has a different shape, it is more preferable that both the first wafer 1 and the second wafer 3 are attracted to deform the wafer.

  Examples of the suction holding mechanism 7 include a method of providing a pattern groove on the stage and sucking the groove portion. The first wafer 1 is dropped from the stage 2 by vacuum suction by the air sealing prevention means 5B. Can be prevented. Examples of the air sealing prevention means 5B include substances having large elastic deformation, such as rubber-based materials (silicon rubber, etc.), resin-based materials, etc., as shown in FIGS. 3 (a) and 3 (b). As shown, it is preferably adsorbed via a suction cup. This is because the wafer can be easily deformed greatly by suction through the suction cup.

  FIG. 4 shows an automatic wafer bonding apparatus 300 according to the third embodiment of the present invention, wherein the stage 2 has a suction holding mechanism 7 for holding the first wafer 1 and the air Inner sealing prevention means 5C has a bonding inhibition mechanism by compressed air injection between the first wafer 1 and the second wafer 3 and at one or more outer peripheral portions of the first wafer 1 and the second wafer 3. It is preferable to have.

The air enclosing prevention means 5C performs compressed air injection between the first wafer 1 and the second wafer 3 and at one or more outer peripheral portions of the first wafer 1 and the second wafer 3. The bonding of both wafers 1 and 3 can be hindered. Further, as the gas to be injected with pressure air, it is preferable to use N ₂ gas that is inexpensive, easy to handle, and highly purified.

  FIGS. 5 (a) and 5 (b) show a bonding propagation model when an air sealing prevention means according to the present invention is provided and a bonding propagation when no air sealing prevention means according to the conventional method is provided, respectively. It is a figure which shows a model. In the figure, the line on the surface of the wafer indicates the propagation state of the bonding, and the white arrow on the outer periphery of the wafer indicates the intersection between the propagation surface and the outer peripheral edge of the wafer, that is, the propagation progress direction vector on the outer periphery of the wafer. The black arrow indicates the normal vector of the propagation surface at the outer periphery of the wafer. As can be seen from FIG. 5 (a) and FIG. 5 (b), by providing air sealing prevention means at the position opposite to the pressing position, the bonding propagation state is changed, and the air pushed out by the bonding is kept in the air. In the first embodiment, by pulling out the insertion jig, in the second embodiment by releasing the vacuum suction, and in the third embodiment By gradually weakening the compressed air jet, all the air can be released to the outer peripheral portion of the wafer, and void defects can be reduced.

  Next, an embodiment of the wafer automatic bonding method of the present invention will be described with reference to the drawings. As shown in FIG. 2 as an example, the wafer automatic bonding method of the present invention is based on the outer periphery of the second wafer 3 placed on the first wafer 1 held on the stage 2 in a state where the bonding is not started. The first wafer 1 and the second wafer 3 are bonded to each other, and the first wafer 1 and the second wafer 3 are sandwiched between the pressed position and the pressed position. The bonding is advanced toward the position, and air sealing between the wafers 1 and 3 when the bonding is completed using the air sealing prevention means 5 provided in advance at the facing position. By preventing and having such a configuration, the void defect of the bonded wafer can be reduced. In addition, it is preferable to perform this method using the wafer automatic bonding apparatus mentioned above.

  1 to 5 show examples of typical embodiments, and the present invention is not limited to these embodiments.

Example 1
A bonded wafer (diameter: 200 mm) was manufactured using the automatic wafer bonding apparatus according to Embodiment 1 of the present invention shown in FIG. The deviation between the first wafer and the second wafer was corrected by an orientation flat / notch guide and a pair of pin guides. Further, a weight was used as the pressing means, and a claw-like member provided on the orientation flat / notch guide at the position opposite to the pressing position was used as the air sealing prevention means. The second wafer was placed by being naturally dropped on the first wafer. Moreover, as a control means, the sequence control by a timer was used, and the process of extracting air was started 1-2 seconds after the weight was lowered.

(Example 2)
A bonded wafer (diameter 200 mm) was manufactured using an automatic wafer bonding apparatus according to Embodiment 2 of the present invention shown in FIG. A method of providing a pattern groove on the stage and sucking the groove portion was used as the suction holding mechanism, and a suction cup made of silicon rubber was used as the air sealing prevention means. Further, the displacement between the first wafer and the second wafer was corrected by an orientation flat / notch guide and a pair of pin guides. Further, a weight was used as the pressing means, and the second wafer was placed by being naturally dropped onto the first wafer. In addition, as a control means, using a sequence control by a timer, a method of starting suction by the suction holding mechanism 1-2 seconds after the weight descends and gradually stopping the suction so as not to stop the propagation of bonding I took.

(Example 3)
A bonded wafer (diameter 300 mm) was manufactured using the automatic wafer bonding apparatus according to Embodiment 1 of the present invention. The deviation between the first wafer and the second wafer was corrected by an orientation flat / notch guide and a pair of pin guides. Further, a weight was used as the pressing means, and a claw-like member provided on the orientation flat / notch guide at the position opposite to the pressing position was used as the air sealing prevention means. The second wafer was placed by being naturally dropped on the first wafer. Moreover, as a control means, the sequence control by a timer was used, and the process of extracting air was started 2 to 4 seconds after the weight was lowered.

(Comparative Example 1)
A bonded wafer (diameter 200 mm) was manufactured using an automatic wafer bonding apparatus that does not have an air sealing prevention means according to a conventional method.

(Comparative Example 2)
A bonded wafer (diameter: 200 mm) was manufactured using the same wafer automatic bonding apparatus as in Example 1 except that the air sealing prevention means was provided at a position of 90 degrees instead of the pressing position and the facing position. .

(Evaluation)
Ultrasonic inspection was performed on the bonded wafers of Examples 1 to 3 and Comparative Examples 1 and 2, and the number of voids having a diameter of 300 microns or more was measured. The values shown in Table 1 are obtained by manufacturing 25 bonded wafers for each example and calculating the average value of the number of voids measured.

  As can be seen from Table 1, it can be seen that Examples 1 to 3 according to the present invention can sufficiently reduce void defects as compared with Comparative Examples 1 and 2.

  The wafer automatic bonding apparatus and wafer automatic bonding method of the present invention set the pressing position by the pressing means to the outer peripheral portion of the wafer, and the bonding end position propagating therefrom is the position opposite to the wafer bonding start position. By confining to air, the voids of bonded wafers are reduced by automatically releasing the collected air to the outside of the wafer by air sealing prevention means so that voids and distortion do not occur. , Production yield can be improved. In addition, by reducing void defects, surface defects caused by peeling when void defects occur, and deterioration in bonding quality such as deterioration of the roughness of the bonding surface due to re-cleaning are improved and stabilized, and correction work is eliminated. Productivity can be improved.

FIG. 1 is a schematic view showing pasting of conventional SOI wafers. FIG. 2 is a schematic diagram showing the wafer automatic bonding apparatus according to the first embodiment of the present invention. FIG. 3A and FIG. 3B are schematic views showing a cross section of an automatic wafer bonding apparatus according to the second embodiment of the present invention. FIG. 4 is a schematic diagram showing a cross section of an automatic wafer bonding apparatus according to the third embodiment of the present invention. FIGS. 5 (a) and 5 (b) show a bonding propagation model when an air sealing prevention means according to the present invention is provided and a bonding propagation when no air sealing prevention means according to the conventional method is provided, respectively. It is a figure which shows a model.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Wafer automatic bonding apparatus 200a, b Wafer automatic bonding apparatus 300 Wafer automatic bonding apparatus 1 1st wafer 2 Stage 3 2nd wafer 4 Pressing means 5 Air sealing prevention means 6 Misalignment correction means 7 Adsorption holding mechanism

Claims (8)

A stage for holding the first wafer;
On the first wafer, pressing means for pressing the outer peripheral portion of the second wafer placed in a state where the bonding does not start,
The first wafer and the second wafer are sandwiched between the pressing position by the pressing means and a position opposite to the pressing position, and the bonding of the first wafer and the second wafer is started by the pressing by the pressing means. An automatic wafer bonding apparatus comprising: air sealing prevention means for preventing air sealing between the two wafers when the bonding proceeds and completes from a position toward the facing position. .   2. The wafer automatic bonding apparatus according to claim 1, further comprising a shift correcting unit provided around the stage and configured to correct a shift between the first wafer and the second wafer.   The wafer automatic bonding apparatus according to claim 2, wherein the misalignment correcting means includes an orientation flat / notch guide and a pair of pin guides.   4. The automatic wafer bonding apparatus according to claim 1, wherein the air sealing prevention means further includes a control means for extracting air so as not to affect the bonding propagation state.   The air sealing means includes an insertion jig that is inserted between the first wafer and the second wafer and at one or more locations on the outer periphery of the first wafer and the second wafer. The wafer automatic bonding apparatus as described in any one of 1-4. The stage has a suction holding mechanism for holding the first wafer;
The air sealing prevention means vacuum-sucks at least one of a surface opposite to the bonding surface of the first wafer and a surface opposite to the bonding surface of the second wafer to forcibly The wafer automatic bonding apparatus according to any one of claims 1 to 4, wherein one wafer and / or the second wafer is deformed. The stage has a suction holding mechanism for holding the first wafer;
The said air sealing prevention means has the bonding inhibition mechanism by a pressurized air injection between the said 1st wafer and the said 2nd wafer and in one or more outer peripheral parts of the said 1st wafer and the said 2nd wafer. Item 5. An automatic wafer bonding apparatus according to any one of Items 1 to 4.   On the first wafer held on the stage, press the outer peripheral part of the second wafer placed in a state where the bonding does not start, start the bonding of the first wafer and the second wafer, press From the position, with the first wafer and the second wafer in between, the pressing position advances the bonding toward the facing position, and using air sealing prevention means provided in advance at the facing position, An automatic wafer bonding method characterized by preventing air sealing between the two wafers when the bonding is completed.

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