Wafer transfer device, wafer transfer method and wafer bonding method

Abstract

The invention relates to the technical field of semiconductor material processing, in particular to a wafer transfer device, a wafer transfer method and a wafer bonding method. The wafer transfer device comprises a transfer disc which is provided with a first surface and a second surface, the first surface is provided with a wafer bearing area and a transition area, the wafer bearing area is internally provided with a plurality of uniformly distributed negative pressure holes, and the first surface is communicated with the second surface through the negative pressure holes; the guide hole intersects with the edge of the wafer bearing area and enables the first surface and the second surface of the transfer disc to be communicated; the negative pressure disc is used for supporting the transfer disc from the second surface of the transfer disc and can form negative pressure; and the lifting platform can support the wafer to reciprocate along the first direction. The wafer transfer device and the wafer transfer method provided by the invention are used for stably transferring wafers in different technological processes, especially in a damaged technological process, and can reduce the formation of pollutants and reduce the pollutant cleaning cost.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor material processing, and in particular to a wafer transfer device, a wafer transfer method and a wafer bonding method. Background Art

[0002] Wafer bonding technology is a semiconductor manufacturing technology used to connect two or more wafers together. This technology is crucial in the manufacture of complex semiconductor devices such as microprocessors and memory chips. Before wafer bonding, the bonding surface of the wafer to be bonded needs to be surface treated so that the bonding surface of the wafer meets the atomic-level flatness and cleanliness. The above surface treatment needs to be completed in multiple process chambers, so the wafer needs to be transported multiple times. The existing wafer operation method mostly uses a high-precision manipulator to contact the wafer from the back of the wafer and transport the wafer in multiple chambers. This wafer transportation method is very efficient and reliable for the transportation of finished wafers, but for wafers that still need surface treatment, there are still some problems in directly using a high-precision manipulator to transport the wafer. For example, before wafer bonding, ions need to be used to bombard the bonding surface of the wafer to activate the bonding surface. When ions bombard the metal wafer placement table, metal contaminants will be generated. These metal contaminants will accumulate on the wafer placement table and the manipulator. If they are not cleaned in time, the process yield will be reduced. For high-precision robots, the cost of disassembly and cleaning is very high and will also affect the overall operation progress. Summary of the invention

[0003] The object of the present invention is to provide a wafer transfer device and a wafer transfer method, which are used to transfer wafers in different process flows, especially damaging processes, such as surface activation process flows, which can reduce the formation of contaminants and reduce the cost of cleaning contaminants.

[0004] To achieve this object, the present invention adopts the following technical solutions:

[0005] A wafer transfer device comprises: a transfer plate having a first surface and a second surface, wherein the first surface is provided with a wafer carrying area and a transition area, and the wafer carrying area is used to carry wafers;

[0006] A plurality of evenly distributed negative pressure holes are provided in the wafer carrying area, and the negative pressure holes connect the first surface and the second surface;

[0007] A guide hole, the guide hole intersecting with an edge of the wafer carrying area, connecting the first surface and the second surface of the transfer plate;

[0008] A negative pressure tray, used to support the transfer tray from the second surface of the transfer tray, the negative pressure tray having a negative pressure space opposite to the second surface of the transfer tray, the negative pressure space being able to form negative pressure;

[0009] A lifting platform can reciprocate along a first direction, the lifting platform is provided with guide posts, the guide posts are at least three, and the end faces of the guide posts are used to support the wafer; the first direction is a direction parallel to the guide posts;

[0010] When the lifting platform reciprocates along the first direction, the end surface of the guide column can be extended and retracted relative to the first surface of the transfer plate.

[0011] Furthermore, the parallelism between the first surface and the second surface of the transfer plate is less than 0.02 mm.

[0012] Furthermore, it also includes a supporting platform, and the negative pressure plate is supported on the supporting platform through the optical axis.

[0013] Furthermore, a linear bearing is provided on the lifting platform, and the linear bearing cooperates with the optical axis.

[0014] Furthermore, it also includes a driver, which is connected to the lifting platform and is used to provide a driving force for the lifting platform to reciprocate along the first direction.

[0015] Furthermore, a contact ring is provided between the negative pressure plate and the transfer plate;

[0016] The contact ring is made of polytetrafluoroethylene.

[0017] Furthermore, the pressure formed in the negative pressure space is -60 kPa to -90 kPa.

[0018] Furthermore, the diameter of the negative pressure hole is not greater than 1 mm.

[0019] The wafer transfer method is performed using the above-mentioned wafer transfer device, comprising:

[0020] placing the transfer plate on the negative pressure plate;

[0021] Maintaining the lifting platform in a first state, wherein the end surface of the guide column is located above the first surface of the transfer plate in the first state;

[0022] Placing the wafer on the end surface of the guide post so that the end surface of the guide post stably supports the wafer;

[0023] Maintaining the lifting platform in a second state, wherein the end surface of the guide column is located below the first surface of the transfer plate, so that the wafer falls on the wafer carrying area of ​​the transfer plate;

[0024] When the lifting platform changes from the first state to the second state, the negative pressure space maintains an adsorption pressure of -60 kPa to -90 kPa;

[0025] A transfer mechanism intervenes to hold the transfer tray for transfer from a second surface, a side, or a transition area from the first surface of the transfer tray.

[0026] Further, after the lifting platform changes to the second state and before the transfer mechanism intervenes, the negative pressure in the negative pressure space is maintained for more than 3 seconds, so that temporary pressure is formed between the wafer and the transfer plate;

[0027] When the transfer mechanism intervenes, the negative pressure in the negative pressure space is closed.

[0028] A wafer bonding method, wherein the transfer plate is transferred to a wafer bonding chamber by using the above-mentioned wafer transfer method, the transfer plate is placed on a lower bonding plate, the wafer on the transfer plate serves as a lower wafer, and an upper bonding plate opposite to the lower bonding plate is included, the upper bonding plate holds an upper wafer;

[0029] The bonding chamber is evacuated to eliminate the temporary pressure between the lower wafer and the transfer plate;

[0030] The upper bonding plate and / or the lower bonding plate are driven to move toward each other, so that the upper wafer is bonded to the lower wafer. After the bonding is completed, the bonded body remains on the transfer plate, and the transfer mechanism intervenes to remove the transfer plate from the bonding chamber. At this time, there is no temporary pressure between the transfer plate and the bonded body, and the bonded body can be removed from the transfer plate by electrostatic adsorption or other methods.

[0031] Beneficial effects of the present invention: The transfer plate in the present invention includes a wafer carrying area and a transition area, the area of ​​the transition area is larger than the area of ​​the wafer carrying area, and when a damaging process such as ion bombardment is performed, the transition area can shield the corresponding machine from damage, thereby increasing the service life of the corresponding machine, extending the cleaning and maintenance cycle of the corresponding machine, and reducing production costs. A transfer mechanism such as a manipulator can transfer the wafer from the second surface of the transfer plate without direct contact with the wafer, thereby avoiding the introduction of contaminants into the wafer.

[0032] Before wafer transfer, the negative pressure plate extracts the air between the wafer and the first surface of the transfer plate through the negative pressure holes on the transfer plate. In addition to removing dust and impurities, it can also form temporary pressure between the wafer and the transfer plate. This temporary pressure presses the wafer on the transfer plate. During the wafer transfer process, the wafer can maintain its relative position with the transfer plate and will not move or float. When the transfer plate carries the wafer for process processing in different chambers, it can maintain the same positioning accuracy. This temporary pressure does not require additional cables and air paths to be arranged on the transfer plate, so it is very easy to transfer the transfer plate between chambers.

[0033] Since the temporary pressure between the wafer and the transfer plate is formed by atmospheric pressure, when the wafer is finally bonded, the temporary pressure between the wafer and the transfer plate will disappear after the bonding chamber is evacuated. When the transfer plate carrying the bonded wafer body leaves the bonding chamber, since there is no temporary pressure between the two, the wafer bond body can be removed from the transfer plate by conventional methods such as electrostatic adsorption and vacuum adsorption. The transfer plate can be reused after cleaning. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a schematic diagram of the wafer transfer device of the present invention when the lifting platform is maintained in the first state;

[0035] Figure 2 It is a schematic diagram of the structure of the transfer plate of the present invention;

[0036] Figure 3 It is a schematic diagram of the structure of the transfer plate of the present invention when carrying wafers;

[0037] Figure 4 is a schematic diagram of the wafer transfer device of the present invention when the lifting platform is maintained in the second state;

[0038] Figure 5 It is a schematic diagram of the wafer transfer device of the present invention from a first perspective without the transfer plate;

[0039] Figure 6 It is a schematic diagram of the wafer transfer device of the present invention from a second viewing angle except for the transfer plate;

[0040] Figure 7 It is a schematic diagram of the wafer transfer device of the present invention from a third viewing angle except for the transfer plate;

[0041] Figure 8 is a schematic diagram of the wafer transfer device of the present invention from a fourth viewing angle excluding the transfer plate;

[0042] In the figure: 1. transfer plate; 2. guide hole; 3. negative pressure hole; 4. wafer; 5. guide column; 6. lifting platform; 7. optical axis; 8. support platform; 9. support leg; 10. driver; 11. contact ring; 12. negative pressure plate; 13. negative pressure hole; 14. negative pressure connector; 15. negative pressure pipeline; 16. coupling; 17. wafer bearing area; 18. transition area. DETAILED DESCRIPTION

[0043] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0044] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0046] In the description of this embodiment, the terms "upper", "lower", "right", etc., directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0047] See also Figure 2 Figure 3 The present application provides a wafer transfer device, including a transfer plate 1, the transfer plate 1 having a first surface and a second surface opposite to each other, wherein the first surface is provided with a wafer carrying area 17 and a transition area 18. The shape of the wafer carrying area 17 is equivalent to the shape of the wafer 4, and is used to carry the wafer 4. The transition area 18 is an annular area surrounding the wafer carrying area 17, which does not contact the wafer 4 and serves as a handling contact area of ​​the transfer plate 1 and a shielding area of ​​the machine.

[0048] See also Figure 3, a number of negative pressure holes 3 are evenly distributed on the wafer carrying area 17 of the transfer tray 1, and the negative pressure holes 3 connect the first surface and the second surface of the transfer tray 1. The aperture of the negative pressure hole 3 is less than 1mm. When negative pressure is formed on the second surface side of the transfer tray 1, the air between the wafer 4 and the wafer carrying area 17 can be sucked away through the negative pressure hole 3. Keeping the aperture of the negative pressure hole 3 less than 1mm can ensure that the contact area between the wafer carrying area 17 and the wafer 4 is as large as possible. When negative pressure is formed on the second surface side of the transfer tray 1 and the air between the wafer 4 and the wafer carrying area 17 is sucked away through the negative pressure holes 3, a temporary pressure caused by atmospheric pressure is formed between the wafer 4 and the wafer carrying area 17, and the temporary pressure can keep the wafer 4 stably on the wafer carrying area 17.

[0049] The transfer plate 1 is also provided with a guide hole 2, which intersects with the circumferential contour line of the wafer bearing area 17, that is, a part of the guide hole 2 is formed on the wafer bearing area 17, and the other part is formed on the transition area 18. In this embodiment, the number of the guide holes 2 is 3, which are evenly distributed in the circumferential direction of the wafer bearing area 17.

[0050] See also Figure 1 Figure 4 The transfer plate 1 is movably supported by the device body.

[0051] See also Figures 5 to 8 In this embodiment, the device body includes a support platform 8 supported by four support legs 9, and three vertical optical axes 7 are arranged on the support platform 8. It also includes a lifting platform 6, and three sets of linear bearings are arranged on the lifting platform 6. The three sets of linear bearings are respectively installed on the three vertical optical axes 7. Under the cooperation of the linear bearings and the optical axes 7, the lifting platform 6 can move up and down along the optical axes.

[0052] A negative pressure plate 12 is also included above the lifting platform 6. In the present embodiment, the negative pressure plate 12 is fixedly mounted at one end of the optical axis 7. The negative pressure plate 12 has a bowl-shaped negative pressure space with an opening facing upward, and a negative pressure hole 13 is provided in the negative pressure space. The negative pressure hole 13 is connected to a negative pressure connector 14 through a negative pressure pipeline 15, and the negative pressure connector 14 is connected to an exhaust device. When the exhaust device is turned on, negative pressure can be formed in the negative pressure space. The upper edge of the negative pressure plate 12 is used to support the transfer plate 1. When the transfer plate 1 is placed on the upper edge of the negative pressure plate 12, the negative pressure space is relatively closed.

[0053] In this embodiment, in order to prevent the second surface of the transfer plate 1 from rubbing against the upper edge of the negative pressure plate 12 to form particulate contaminants, a contact ring 11 is provided on the upper edge of the negative pressure plate 12. The second surface of the transfer plate 1 is isolated from the upper edge of the negative pressure plate 12 by the contact ring 11. The contact ring 11 is made of polytetrafluoroethylene and has wear-resistant and dust-proof effects.

[0054] Three guide posts 5 are provided on the lifting platform 6, and the guide posts 5 move with the lifting platform 6. The upper end surface of the guide post 5 is used to support the wafer 4. In order to stably support the wafer 4, the upper end surface of the guide post 5 is set as a boss structure, and the boss can abut against the circumferential wall of the wafer 4.

[0055] When the lifting platform 6 rises, the guide pillars 5 support the wafer 4 to move upward, so that the wafer 4 is away from the transfer plate 1. When the lifting platform 6 descends, the guide pillars 5 support the wafer 4 to move downward, so that the wafer 4 falls on the wafer carrying area 17 of the transfer plate 1.

[0056] It also includes a driver 10, which is connected to the lifting platform 6 through a coupling 16 and is used to provide power for the lifting platform 6 to move up and down.

[0057] In this embodiment, the wafer transfer device can be used to transfer wafers in the following manner: first, place the transfer plate 1 on the negative pressure plate 12, and raise the lifting platform 6 so that the upper end surface of the guide column on the lifting platform 6 is located above the first surface of the transfer plate 1. Stably place the wafer 4 on the upper end surface of the guide column 5. Lower the lifting platform 6, and support the wafer 4 with the guide column 5 to lower synchronously until the upper end surface of the guide column 5 sinks into the first surface of the lifting platform 6, so that the wafer 4 falls on the wafer carrying area 17.

[0058] When the lifting platform 6 begins to descend, the vacuum device is turned on to maintain an adsorption pressure of -60kPa to -90kPa in the negative pressure space, and the adsorption pressure continues for more than 3 seconds after the wafer 4 falls on the wafer carrying area 17. Under this condition, the air between the wafer 4 and the wafer carrying area 17 will be extracted, and a temporary pressure will be formed between the wafer 4 and the transfer plate 1. The temporary pressure presses the wafer 4 on the transfer plate 1, and the wafer 4 can maintain its relative position with the transfer plate 1 during the transfer of the wafer 4, and will not move or float. When the transfer plate 1 carries the wafer 4 for process processing in different chambers, the same positioning accuracy can be maintained. This temporary pressure does not require additional cables and air paths to be arranged on the transfer plate, so it becomes very easy for the transfer plate to be transported between the chambers.

[0059] During the transfer, the transfer plate 1 is held by the transfer mechanism from the second surface, the side, and the transition zone of the first surface of the transfer plate 1 and sent to each chamber for process treatment. During this process, the transfer mechanism will not come into direct contact with the wafer to avoid introducing contaminants into the wafer. During the process, since the area of ​​the transition zone 18 is larger than the area of ​​the wafer supporting area 17, when performing damaging processes such as ion bombardment, the transition zone 18 can shield the corresponding machine from damage, thereby increasing the service life of the corresponding machine, extending the cleaning and maintenance cycle of the corresponding machine, and reducing production costs.

[0060] In this embodiment, the wafer 4 after process treatment can also be sent to the bonding chamber together with the transfer tray 1 for wafer bonding. At this time, the transfer tray 1 is placed on the lower bonding tray, and the wafer 4 on the transfer tray serves as the lower wafer. It also includes an upper bonding tray opposite to the lower bonding tray. The upper bonding tray holds the upper wafer, and the bonding chamber is evacuated to eliminate the temporary pressure between the lower wafer and the transfer tray, and the upper bonding tray and the lower bonding tray are driven to move toward each other, so that the upper wafer and the lower wafer are bonded. After the bonding is completed, the bonded body remains on the transfer tray, and the transfer mechanism intervenes to take out the transfer tray from the bonding chamber. At this time, there is no temporary pressure between the transfer tray and the bonded body, and the bonded body can be removed from the transfer tray by electrostatic adsorption or the like. The transfer tray can be reused after cleaning.

[0061] If the processed wafer 4 does not need to be bonded, the transfer plate 1 together with the wafer 4 can be sent back to the negative pressure plate 12, the lifting platform 6 can be raised, the wafer 4 can be lifted up by the guide column 5, the wafer 4 can be moved away from the transfer plate 1, and then the wafer 4 can be removed by the transfer mechanism. The transfer plate can be reused after cleaning.

[0062] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A wafer transfer device, characterized in that: include: The transfer plate has a first surface and a second surface, wherein the first surface is provided with a wafer carrying area and a transition area, and the wafer carrying area is used to carry wafers; A plurality of evenly distributed negative pressure holes are provided in the wafer carrying area, and the negative pressure holes connect the first surface and the second surface; A guide hole, the guide hole intersecting with an edge of the wafer carrying area, connecting the first surface and the second surface of the transfer plate; A negative pressure tray, used to support the transfer tray from the second surface of the transfer tray, the negative pressure tray having a negative pressure space opposite to the second surface of the transfer tray, the negative pressure space being able to form negative pressure; A lifting platform, which can reciprocate along a first direction, is provided with guide posts, the number of the guide posts is at least 3, and the end faces of the guide posts are used to support the wafer; When the lifting platform reciprocates along the first direction, the end surface of the guide column can be extended and retracted relative to the first surface of the transfer plate.

2. The wafer transfer device according to claim 1, characterized in that: It also includes a supporting platform, and the negative pressure plate is supported on the supporting platform through an optical axis.

3. The wafer transfer device according to claim 2, characterized in that: The lifting platform is provided with a linear bearing, and the linear bearing cooperates with the optical axis.

4. The wafer transfer device according to claim 3, characterized in that: It also includes a driver, which is connected to the lifting platform and is used to provide a driving force for the lifting platform to reciprocate along the first direction.

5. The wafer transfer device according to claim 1, characterized in that: A contact ring is also provided between the negative pressure plate and the transfer plate; The contact ring is made of polytetrafluoroethylene.

6. The wafer transfer device according to claim 1, characterized in that: The pressure formed in the negative pressure space is -60 kPa to -90 kPa.

7. The wafer transfer device according to claim 1, characterized in that: The diameter of the negative pressure hole is no more than 1 mm.

8. A wafer transfer method, characterized in that: The method is carried out using the wafer transfer device according to any one of claims 1 to 7, comprising: placing the transfer plate on the negative pressure plate; Maintaining the lifting platform in a first state, wherein the end surface of the guide column is located above the first surface of the transfer plate in the first state; Placing the wafer on the end surface of the guide post so that the end surface of the guide post stably supports the wafer; Maintaining the lifting platform in a second state, wherein the end surface of the guide column is located below the first surface of the transfer plate, so that the wafer falls on the wafer carrying area of ​​the transfer plate; When the lifting platform changes from the first state to the second state, the negative pressure space maintains an adsorption pressure of -60 kPa to -90 kPa; A transfer mechanism intervenes to hold the transfer tray for transfer from a second surface, a side, or a transition area from the first surface of the transfer tray.

9. The wafer transfer method according to claim 8, characterized in that: After the lifting platform changes to the second state and before the transfer mechanism intervenes, the negative pressure in the negative pressure space is maintained for more than 3 seconds, so that temporary pressure is formed between the wafer and the transfer plate; When the transfer mechanism intervenes, the negative pressure in the negative pressure space is closed.

10. A wafer bonding method, characterized in that: The transfer tray is transferred to a wafer bonding chamber by using the wafer transfer method of claim 8 or 9, the transfer tray is placed on a lower bonding tray, the wafer on the transfer tray serves as a lower wafer, and an upper bonding tray opposite to the lower bonding tray is included, the upper bonding tray holds an upper wafer; The bonding chamber is evacuated to eliminate the temporary pressure between the lower wafer and the transfer plate; The upper bonding plate and / or the lower bonding plate are driven to move toward each other so that the upper wafer is bonded to the lower wafer.

Images