JP2005136285A - Method and device for sticking wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stick two wafers to one another effectively with high accuracy. <P>SOLUTION: Spin cleaning units (9), (10) for cleaning and drying two wafers (2L), (2R) respectively are provided, and a pair of sticking chucks (16), (17) are provided between the cleaning units (9) and (10). The sticking chucks (16), (17) can be moved to a receiving position and a sticking position. The cleaned and dried wafers are respectively chucked and retained to the sticking chucks (16), (17) in a standing state at the receiving position to be aligned. After the alignment, the sticking chucks (16), (17) are moved to the sticking position opposed to the wafers (2L), (2R). At the sticking position, the sticking chucks (16), (17) are closed to one another to stick the wafers (2L), (2R) to one another. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a wafer bonding method and apparatus in which two wafers are superposed and bonded in a close contact state.

When two wafers are stuck together like a SOI (Silicon On Insulator) wafer, if bubbles or particles enter between the wafers and voids occur, inconvenience occurs in the subsequent process. Various methods and apparatuses for bonding wafers to be removed have been proposed. In general, such a bonding apparatus is configured to be bonded with another wafer placed on the upper surface of the wafer held horizontally (for example, see Patent Document 1). The footprint is also increased, and the wafers are moved one by one by a robot or the like, so the workability is not good. In addition, it is also known that the wafer is tilted so that the orientation flat of the wafer is on the lower side and the wafer surface is slanted and pressed from one position in the orientation flat forming region (see, for example, Patent Document 2). There was also a risk of sticking out of alignment because of uncertain support.
JP 2002-190435 A (Claims, FIGS. 1 and 2) JP 2001-937787 A (Claims, FIG. 1)

  SUMMARY OF THE INVENTION An object of the present invention is to provide a wafer laminating method and apparatus capable of reliably adhering to a peripheral portion of a wafer without causing any deviation or void, and capable of fully and efficiently laminating a wafer. Is to provide.

  According to the present invention, the step of cleaning and drying two wafers to be bonded, the step of aligning the wafer after cleaning and drying with a pair of bonding chucks, and the aligned wafers face each other. And a step of moving the bonding chuck to a bonding position and a step of bringing the bonding chuck close together so as to overlap the wafer held by the bonding chuck. Preferably, the laminating chuck holds the wafer so that the laminating surface of the wafer is in an upright state, and presses the wafer from the central part to the outer peripheral part when the wafers are stacked. It includes a process.

  Further, according to the present invention, two cleaning / drying means for individually cleaning and drying two wafers, a pair of bonding chucks each holding the wafer after cleaning and drying, and the wafer are carried into the cleaning / drying means. The wafer after cleaning and drying is taken out from the cleaning and drying means and carried to the bonding chuck, the alignment means for aligning the wafer held by the bonding chuck, and the aligned wafer are aligned. Thus, there is provided a wafer laminating apparatus comprising means for moving the laminating chuck to the laminating position and means for bringing the laminating chuck close to overlap the wafer held by the laminating chuck. .

In the wafer bonding apparatus, the bonding chuck has a movable part that contacts the center of the wafer and holds the wafer, and a pressure contact part that exists on the outer periphery of the movable part and contacts the peripheral part of the wafer. Is provided so that the wafer can be moved forward and backward in the direction of the opposing bonding chuck, and the bonding chuck is provided with an elastic means for pressing the wafer from the center portion toward the outer periphery, and one of the bonding means is used as the elastic means. A wafer bonding apparatus is provided in which the pressure contact portion of the chuck is hard and an elastic pressing member is provided on the pressure contact portion of the other bonding chuck.

  The present invention is configured as described above, and after cleaning and drying two wafers to be bonded individually, the wafers are respectively held by a pair of bonding chucks, and the wafers are aligned while being held by the bonding chucks. After that, the bonding chuck is moved to the bonding position so that the two wafers face each other, and the wafer is overlapped with the bonding chuck close at the bonding position. The two wafers can be brought into close contact with the surrounding area without any deviation, and the washed and dried wafers are held in an upright state so that they are less affected by particles and have a small footprint. can do. In addition, when the two wafers are held and bonded by the bonding chuck, the next two wafers are transferred to the cleaning and drying process, so that cleaning and bonding can be performed in parallel. Wafers can be bonded efficiently.

  The bonding chuck comprises a movable part that contacts the center of the wafer and holds the wafer, and a pressure contact part that exists on the outer periphery of the movable part and contacts the peripheral part of the wafer, and the movable chuck is opposed to the movable chuck. If the movable part is provided so as to be able to advance and retreat in the direction, the wafer held by the movable part in a state in which the movable part protrudes from the pressure contact part is first pressed by the movable part when the bonding chuck is brought close to the wafer. Further, when the bonding chuck approaches, the movable part moves backward, and the pressure contact part comes in contact with the wafer and is gradually pressed toward the outer peripheral part, so that the air bubbles can be reliably adhered without confining bubbles between the wafers.

  FIG. 1 is a plan view showing an embodiment of an apparatus according to the wafer bonding method of the present invention. In the figure, L cassettes (3) and (4) containing two wafers to be bonded, that is, an L wafer (2L) positioned on the left side in the figure, are placed on the carry-in side of the apparatus body (1). And an R cassette stage (8) for mounting an R cassette (6) and (7) containing an R wafer (2R) located on the right side in the figure. Spin cleaning units (9) and (10) for respectively cleaning and drying the wafer are provided, and the wafers taken out from the cassette by the transfer means (11) and (12) such as a loader robot are respectively cleaned by the cleaning unit (9) and Carry in (10).

  The cleaning units (9) and (10) are subjected to brush cleaning so as to remove particles and the like adhering to both surfaces of the wafer, or spin processing is performed using megasonic showers (13) and (14), and pure water rinse is performed. Wash and spin dry. At this time, heating means such as a halogen lamp (15) or a heater is provided at the upper part of the cleaning unit or other appropriate position, for example, a receiving position to be described later so as to surely remove moisture from the treated wafer surface, and then dried. be able to.

  A pair of bonding chucks (16) and (17) for holding and bonding the wafer is provided between the cleaning units (9) and (10). The laminating chucks (16) and (17) are movably provided so as to move to the receiving position and the laminating position, and when in the receiving position, the cleaning means ( 9) The wafer taken out from (10) is received, and the bonded surface is held upright. Therefore, the transport means (11), (12) uses a robot that operates in four axes so that the wafer can be transferred between a horizontal state and a vertical state. Note that the wafer may be held so that the bonding surface is in a horizontal state.

  At the receiving position, the outer periphery of the wafer, the orientation flat, the notch and the like are detected, and the center position and directionality of the wafer are aligned. As the alignment means, an appropriate means can be used. In the embodiment shown in the figure, a CCD camera (18) is provided at the receiving position as shown in FIGS. The wafers held on the alignment chucks (16) and (17) are rotated by an appropriate driving mechanism, moved up and down, and moved back and forth for image processing for alignment. That is, with reference to FIGS. 3 to 5, the drive mechanism shown in the embodiment includes a pulse motor, and in order to align the notch and orientation flat of the wafer, the rotation pulse motor (19) is driven to support the wafer support shaft. To rotate (20) and adjust the height, the pulse motor for vertical movement (21) is driven to move the bonding chuck bodies (16), (17) up and down to move back and forth to the image processing position. The longitudinal movement pulse motor (23) is driven to move the bonding chucks (16), (17) back and forth.

  After the alignment as described above, the position moving pulse motor (24) is driven, and the bonding chucks (16) and (17) are placed at the bonding positions where the wafers (2L) and (2R) face each other. Moving. In addition, an air cylinder etc. can also be used as a means to move as mentioned above.

  When the front / rear pulse motor (23) is driven to move the bonding chucks (16), (17) to the position where the wafers come into contact with each other, the wafers held on the chucks are stacked and bonded. Can be combined. While the wafer holding structure by the bonding chuck can be variously configured, in the embodiment shown in FIG. 5, each chuck (16), (17) is in contact with the center of each wafer, and the wafer is held by a vacuum action. There are movable parts (25L) and (25R) to be sucked and held, and pressure contact parts (26L) and (26R) that are on the outer periphery of the movable parts (25L) and (25R) and contact the peripheral part of the wafer. The parts (25L) and (25R) are provided so as to be able to advance and retreat in the direction of the opposite bonding chuck. The movable portions (25L) and (25R) have a flat surface in contact with the wafer and are biased by a spring to advance when the bonding chucks (16) and (17) are separated from each other. For example, about 5 mm protrudes slightly from the outer end of the central hole (27) of (26L) and (26R), and the wafer is sucked and held in this state. When the wafers are overlapped with the laminating chucks (16) and (17) close to each other, the movable parts (25L) and (25R) are pressed, and the whole is placed in the center hole (27) against the spring. When the wafer moves backward and comes in contact with the wafer, the vacuum to each movable part is turned off to stop the wafer from being sucked. Note that the outer diameters of the pressure contact portions (26L) and (26R) are formed to be slightly larger than the maximum diameter of the wafers to be bonded, and are preferably formed to have an appropriate size that can also be used for wafers of different sizes. .

  The bonding chuck is provided with appropriate elastic means for pressing the overlapped wafer from the central portion toward the outer peripheral portion. The elastic means can be variously configured, and in the embodiment shown in the figure, the movable portion (25L) on the side of the bonding chuck (16) that holds the L wafer (2L) is held, and the R wafer (2R) is held. The spring is biased by a spring force stronger than that of the movable portion (25R) on the bonding chuck (17) side, and these spring forces can be adjusted by the dial (28) with a memory. Then, the movable portion (25R) on the R wafer (2R) side is made of a hard material such as an aluminum material up to the surface in contact with the wafer, and the movable portion (25L) on the L wafer (2L) side is as shown in FIG. An elastic pressing piece (29) made of a heat-resistant elastic material such as silicon rubber material is provided on the surface. The elastic pressing piece (29) is mounted on the front surface of the movable part main body (30) made of an aluminum material, but the contact surface (31) of the movable part main body (30) and the elastic pressing piece (29) is explained. As shown exaggerated for convenience, it is formed in a large spherical shape. With this configuration, when the bonding chucks (16) and (17) are brought close to each other, the central portion of the wafer is strongly pressed, and thereafter, the pressing force is gradually transmitted to the peripheral portion through the elastic pressing piece to press the outer periphery. be able to.

  Further, an elastic means is also provided in the pressure contact portion. That is, in the embodiment, the pressure contact portion (26R) on the side in contact with the R wafer (2R) is made of a hard material with little thermal strain or processing strain such as ceramics or glass, and a heater such as a rubber heater (32) on the inner surface. Or a heating means such as a heating lamp is provided in the vicinity so that heating can be performed in a range of about 0 to 150 ° C., and the surface is coated with Teflon (registered trademark) or the like. When heated in this way, when the wafers are bonded together, moisture and the like on the bonding surface of the wafers volatilize, and the wafers can be further adhered.

  On the other hand, an elastic pressing member (33) is provided at the pressure contact portion (26L) on the side in contact with the L wafer (2L) so as to gradually press the wafer from the central portion toward the outer peripheral portion. The pressing member (33) can be configured in various ways, and in the embodiment shown in the figure, as shown in FIGS. 7 and 8, a narrow blade-like piece made of a heat-resistant elastic material such as a silicone rubber material ( 34) ... and the blade-like piece (34) ... is attached radially so that the center side is high and the outer peripheral side is slightly lower than that, or the outer peripheral part is attached according to the outer diameter of the wafer. A peripheral piece (34a) or (34b) may be provided so that it can be pressed. It is also possible to wind and attach the blade-like pieces in a spiral shape, or to wrap the outside with a dust-proof cover (34c) having appropriate air permeability. When the pressing member (33) comes into contact with the wafer by such a configuration, the wafer is gradually pressed from the central portion toward the outer peripheral portion, and air between the wafers can be removed. The pressing mechanism as described above can also be applied when two wafers are bonded in a horizontal state.

Behind the bonding chucks (16), (17) is a conveying means (36) such as an unloader robot for taking out the bonded wafer (2) from the chuck and storing it in the cassette (35). Is provided. The transfer means (36) is composed of a robot that operates four axes in the same manner as the transfer means (11) and (12). In addition, an inspection stage (37) having an inspection device for inspecting the quality of the bonded wafer (2) is provided before being stored in the cassette (35), so that good and defective products are stored in separate cassettes. You may comprise.

In addition, the cassette section, cleaning unit section, bonding chuck section, etc. in the apparatus main body (1) are each partitioned by a simple wall, and a humidity control unit, a ulpa filter unit, a chiller unit, etc. are provided at appropriate locations, and the temperature is set for each partition. It is preferable to manage the humidity and the like, and it is preferable that N ₂ gas is supplied to the bonding position and bonding is performed in an N ₂ atmosphere.

  With the above configuration, the two wafers (2L) and (2R) to be bonded stored in the cassettes (3), (4), (6), and (7) are individually brought into the washing and drying process. Then, it is cleaned and dried, and after cleaning and drying, alignment is performed while being held by the bonding chucks (16) and (17). After the alignment, the bonding chucks (16) and (17) are moved to the bonding position so that the wafers (2L) and (2R) face each other and are brought close to each other. Therefore, the wafers (2L) and (2R) ) Are perfectly superimposed without any deviation to the periphery.

  In addition, when the wafer is bonded at the bonding position, the next two wafers are processed in parallel in the washing and drying process so that the wafers can be bonded efficiently and bonded in an upright state. Therefore, there is little influence of particles and the like.

1 is a schematic plan view showing an embodiment of the present invention. Explanatory drawing of an image recognition process part. The top view of a bonding chuck | zipper part. The front view of a bonding chuck | zipper part. The partially cutaway enlarged front view of the bonding chuck. The expanded sectional view of one movable part. The enlarged front view of one press-contact part. The side view of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Apparatus main body 2L, 2R, 2 Wafer 9, 10 Spin washing unit 11, 12 Conveying means 16, 17 Bonding chuck 18 CCD camera 19 Pulse motor for rotation 21 Pulse motor for vertical movement 23 Pulse motor for forward / backward movement 24 Pulse for position movement Motor 25L, 25R Movable part 26L, 26R Pressure contact part 29 Elastic pressing piece 32 Rubber heater 33 Pressing member 36 Conveying means

Claims (10)

A process of individually washing and drying the two wafers to be bonded;
A process of holding and aligning the wafer after washing and drying on a pair of bonding chucks;
Moving the bonding chuck to a bonding position so that the aligned wafers face each other;
A wafer bonding method comprising the step of bringing the bonding chuck close to overlap the wafer held by the bonding chuck.   2. The wafer bonding method according to claim 1, wherein the bonding chuck holds the wafer so that the wafer bonding surface is in an upright state.   3. The wafer bonding method according to claim 1 or 2, further comprising a step of pressing the overlapped wafers from the central part toward the outer peripheral part by an elastic means when the wafers are overlapped.   4. The wafer bonding method according to claim 1, further comprising a step of heating the wafer when the wafers are overlapped.   Two cleaning / drying means for individually cleaning and drying the two wafers, a pair of bonding chucks each holding the wafer after the cleaning / drying, and the wafer is carried into the cleaning / drying means and the wafer after the cleaning / drying is transferred to the cleaning / drying means. The conveying means for taking out from the cleaning / drying means and carrying it into the bonding chuck, the alignment means for aligning the wafer held by the bonding chuck, and the bonding chuck are attached so that the aligned wafers face each other. A wafer bonding apparatus comprising: means for moving to a bonding position; and means for bringing the bonding chuck close to overlap the wafer held by the bonding chuck.   6. The wafer bonding apparatus according to claim 5, wherein the bonding chuck holds the wafer so that the wafer bonding surface is in an upright state.   7. The wafer bonding apparatus according to claim 5 or 6, wherein the bonding chuck includes elastic means for pressing the stacked wafers from a central portion toward an outer peripheral portion when the wafers are stacked.   The bonding chuck has a movable portion that contacts the center of the wafer and holds the wafer, and a pressure contact portion that exists on the outer periphery of the movable portion and contacts the peripheral portion of the wafer. 8. A wafer bonding apparatus according to claim 5, wherein the wafer bonding apparatus is provided so as to be capable of advancing and retreating.   A pressing member is provided at the pressure contact portion of one bonding chuck of the pair of bonding chucks so as to elastically press the wafer from the center portion toward the outer peripheral portion, and the pressure contact portion of the other bonding chuck is hard. 9. The wafer bonding apparatus according to claim 8, wherein the wafer bonding apparatus is made of a material.   10. The wafer bonding apparatus according to claim 5, wherein the bonding chuck is provided with heating means.

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