CN113851414A

CN113851414A - Laser de-bonding method

Info

Publication number: CN113851414A
Application number: CN202111036061.XA
Authority: CN
Inventors: 李纪东; 张紫辰; 侯煜; 张昆鹏; 张喆; 张彪; 易飞跃; 杨顺凯
Original assignee: Beijing Zhongke Leite Electronics Co ltd
Current assignee: Beijing Zhongke Leite Electronics Co ltd
Priority date: 2021-09-03
Filing date: 2021-09-03
Publication date: 2021-12-28

Abstract

The invention provides a laser de-bonding method which is used for de-bonding a piece to be de-bonded, wherein the piece to be de-bonded comprises a first layer structure and a second layer structure bonded through a bonding layer. The laser de-bonding method firstly calculates the intrinsic absorption long wave limit of a laser beam according to the forbidden bandwidth of a bonding layer material; and then, the wavelength of the final laser beam can be determined according to the intrinsic absorption long wave limit of the laser beam, so that the proper laser wavelength can be determined quickly, the difficulty of determining the laser wavelength is simplified, the workload is reduced, and the cost is reduced. When the laser beam with the finally determined wavelength is adopted to scan the bonding layer, the light absorption efficiency of the bonding layer can be ensured in a larger interval, and then the bonding layer can be heated to a phase change state in a shorter time, so that the bonding of the bonding layer with the first layer structure and the second layer structure is rapidly released, the rapid bonding is facilitated, and the bonding efficiency is improved.

Description

Laser de-bonding method

Technical Field

The invention relates to the technical field of semiconductor manufacturing, in particular to a laser bonding removing method.

Background

During the fabrication of chips, a large number of microelectronic devices are typically fabricated on a wafer by etching, deposition, polishing, etc. Wafers are thin slices cut from a single crystal silicon ingot, typically between 0.3mm and 0.9mm thick, and are seen to be very thin. Since the thickness of a wafer is thin and a plurality of etching, polishing, cleaning, etc. are required when various circuits are processed on the wafer, the wafer is temporarily bonded to a substrate before the processing. And then carrying out deposition, etching and other processes on the surface of the wafer so as to manufacture various microelectronic devices on the surface of the wafer. After the wafer processing is completed, the wafer and the substrate need to be debonded to separate the wafer and the substrate, so that the subsequent wafer scribing process can be performed.

In the prior art, a laser debonding mode is generally adopted in the debonding process of the wafer and the substrate. Specifically, a laser beam is focused on a bonding layer between a wafer and a substrate, and the bonding layer is scanned to heat the bonding layer, so that the bonding layer is in a molten state. After scanning the entire bonding layer, laser heating was stopped, and the wafer and the substrate were peeled off using a transfer device having a suction cup. In determining the wavelength of the laser, the prior art generally adopts a mode of experiment by laser wavelength to find the proper laser wavelength. However, the method needs a lot of experiments to determine the wavelength of the laser, which is tedious, and increases workload and cost.

Disclosure of Invention

The invention provides a laser de-bonding method, which is convenient for quickly determining proper laser wavelength, simplifies the difficulty of determining the laser wavelength, reduces the workload and reduces the cost.

The invention provides a laser de-bonding method which is used for de-bonding a piece to be de-bonded, wherein the piece to be de-bonded comprises a first layer structure and a second layer structure bonded through a bonding layer. The laser bonding method comprises the following steps:

holding the part to be unbonded on an object stage, wherein the first layer structure is in contact with the object stage;

a laser system arranged to generate a laser beam;

according to the forbidden band width E of the bonding layer material_g0Calculating the intrinsic absorption long wavelength limit of the laser beam according to the following formula:

determining the wavelength of the laser beam to be lambda 0 according to the intrinsic absorption long wave limit of the laser beam, wherein lambda 0 is not less than lambda c;

controlling the laser beam to penetrate through the second layer structure and focus on the bonding layer;

and controlling light spots of the laser beams to scan on the bonding layer, so that the bonding layer is heated to generate phase change, and the bonding of the bonding layer with the first layer structure and the second layer structure is removed.

In the scheme, the intrinsic absorption long-wave limit of the laser beam is calculated firstly according to the forbidden bandwidth of the bonding layer material; and then, the wavelength of the final laser beam can be determined according to the intrinsic absorption long wave limit of the laser beam, so that the proper laser wavelength can be determined quickly, the difficulty of determining the laser wavelength is simplified, the workload is reduced, and the cost is reduced. When the laser beam with the finally determined wavelength is adopted to scan the bonding layer, the light absorption efficiency of the bonding layer can be ensured in a larger interval, and then the bonding layer can be heated to a phase change state in a shorter time, so that the bonding of the bonding layer with the first layer structure and the second layer structure is rapidly released, the rapid bonding is facilitated, and the bonding efficiency is improved.

In a specific embodiment, the second layer structure has a forbidden band width of E_g1Wherein E is_g1＞E_g0. The laser beam can easily penetrate through the second layer structure to heat the bonding layer.

In one embodiment, the wavelength of the laser beam

The laser beam penetrating through the second layer structure can have less energy loss, so that the second layer structure can be prevented from being overheated, and the bonding layer heating efficiency can be improved.

In a specific embodiment, before controlling the laser beam to be focused on the bonding layer after transmitting through the second layer structure, the laser de-bonding method further includes: arranging a sucker assembly, wherein the sucker assembly comprises a sucker adsorbed on the surface of the second layer structure; and the forbidden band width of the sucker material is E_g2Wherein E is_g2＞E_g0. Controlling the laser beam to pass through the second layer structure and then focus on the bonding layer comprises: and controlling the laser beam to sequentially pass through the sucking disc and the second layer structure from top to bottom and then focus on the bonding layer. Through adsorbing the sucking disc on the second floor structure surface earlier, later see through sucking disc and second floor structure back from the top down in proper order by the laser beam, focus on separating on the bonding layer, thereby whole or partial region back of bonding layer is separated in the facula scanning of laser, need not to remove and fixed suction disc, can pull the sucking disc at the very first time and make first floor structure and second floor structure separation, thereby shorten the laser facula scanning and end to the interval time of upwards pulling between the second floor structure, prevent interval time overlength, and lead to the bonding layer after the heating to solidify and take place to bond once more, thereby reduce and peel off the degree of difficulty.

In one embodiment, the forbidden band width E of the sucking disc material_g2The forbidden band width E of the second layer structure material is larger than or equal to_g1. So as to reduce the energy loss of the laser when the laser penetrates the chuck and the second layer structure.

In a specific embodiment, the suction cup assembly further comprises a tension mechanism coupled to the suction cup. Controlling the light spot of the laser beam to scan on the bonding layer, heating the bonding layer to generate phase change, and removing the bonding of the bonding layer with the first layer structure and the second layer structure comprises: controlling a light spot of the laser beam to scan a first area of the bonding layer, heating the bonding layer in the first area to generate phase change, and removing the bonding of the bonding layer in the first area with the first layer structure and the second layer structure; wherein the first region is a partial region of the bonding layer. Thereafter, the stretching mechanism is controlled to pull the suction cup upward to separate the first layer structure and the second layer structure at a position coinciding with the first region. And sequentially controlling a light spot of the laser beam to scan the second area to the Nth area of the bonding layer, and after scanning one area, controlling a stretching mechanism to pull the sucker upwards so as to separate the first layer structure and the second layer structure at a position which is overlapped with the just scanned area. Wherein the first region to the Nth region constitute the entire region of the bonding layer. After the light spot through laser scans the partial area of the bonding layer, the second layer structure is stretched immediately afterwards, two layer structures are separated at the position where the partial area coincides, the time interval between the light spot scanning and the stretching of the second layer structure is shortened more, thereby the bonding layer of the partial area which is just heated can be prevented more safely from solidifying, the laser de-bonding is adopted, the sucking disc is pulled to separate the stripping mode, the phenomenon that the two layer structures are bonded again due to the fact that the bonding material in a molten state is cooled and solidified again can be prevented more safely from occurring between the two layer structures, and the stripping difficulty is further reduced.

In one embodiment, the first layer structure is a wafer and the second layer structure is a substrate. So as to reduce the difficulty of peeling the wafer and the substrate in the laser bonding process. Meanwhile, the laser beam is prevented from penetrating through the wafer, and the influence of the laser beam on the electrical performance of the microelectronic device on the wafer can be prevented.

In a specific embodiment, each of the first to N-1 th regions is a circular ring-shaped region, and the nth region is a circular region. And the first region to the Nth region are sequentially arranged from the outer ring to the inner ring of the bonding layer. So as to facilitate the diffusion of the gaseous or plasma species generated during the laser debinding process out of the two layer structure.

In one embodiment, the chuck and substrate are both made of quartz. To prevent the chuck and substrate from affecting the laser transmissivity.

In a particular embodiment, the laser system further comprises a galvanometer system. The control of scanning the light spot of the laser beam on the bonding layer specifically comprises: and controlling the galvanometer system to scan the light spot of the laser beam on the bonding layer. And the galvanometer system is adopted to control the light spots to scan on the bonding layer, so that the scanning difficulty is simplified.

Drawings

Fig. 1 is a flowchart of a laser bonding method according to an embodiment of the present invention;

FIG. 2 is a graph of the transmission of laser light versus wavelength provided by an embodiment of the present invention;

fig. 3 is a schematic structural diagram of laser bonding according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of another laser-based photolytic bond configuration provided by an embodiment of the present invention;

fig. 5 is a schematic structural diagram of a suction cup and a stretching mechanism according to an embodiment of the present invention;

FIG. 6 is a schematic diagram of a longitudinal section of a chuck according to an embodiment of the present invention;

FIG. 7 is a schematic structural diagram of an adsorption channel on an adsorption end face according to an embodiment of the present invention;

fig. 8 is a schematic diagram illustrating division of different regions on a bonding layer according to an embodiment of the present invention;

FIG. 9 is a schematic structural diagram of another embodiment of a suction cup and stretching mechanism;

FIG. 10 is a schematic structural view of a pull rod and a suction cup according to an embodiment of the present invention;

FIG. 11 is a schematic structural view of a suction surface of another chuck according to an embodiment of the present invention;

FIG. 12 is a schematic structural diagram of another adsorption channel on an adsorption end face according to an embodiment of the present invention;

FIG. 13 is a schematic side view of another embodiment of a chuck in accordance with the present invention;

fig. 14 is a schematic structural diagram of another stretching mechanism according to an embodiment of the present invention.

Reference numerals:

10-stage 11-first layer structure 12-second layer structure 13-bonding layer

21-laser 22-focusing lens 23-galvanometer system

30-suction cup 31-adsorption end face 32-adsorption channel 33-connection end face

34-adsorption zone 35-vacuum

40-stretching mechanism 41-pull rod 42-support 43-support arm 44-lifting mechanism

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

For convenience of understanding of the laser de-bonding method provided by the embodiment of the present invention, an application scenario of the laser de-bonding method provided by the embodiment of the present invention is first described below, where the laser de-bonding method is applied to a process of laser de-bonding a to-be-de-bonded piece, where the to-be-de-bonded piece includes a first layer structure and a second layer structure bonded by a bonding layer. The laser de-bonding method is described in detail below with reference to the accompanying drawings.

Referring to fig. 1 and fig. 3, a laser bonding method according to an embodiment of the present invention includes:

step 10: holding the part to be unbonded on the object table 10, wherein the first layer structure 11 is in contact with the object table 10;

step 20: a laser system arranged to generate a laser beam;

step 30: according to the forbidden band width E of the bonding layer 13 material_g0Calculating the intrinsic absorption long wavelength limit of the laser beam according to the following formula:

step 40: determining the wavelength of the laser beam to be lambda 0 according to the intrinsic absorption long wave limit of the laser beam, wherein lambda 0 is not less than lambda c;

step 50: controlling the laser beam to penetrate through the second layer structure 12 and then focus on the bonding layer 13;

step 60: and controlling the light spot of the laser beam to scan on the bonding layer 13, so that the bonding layer 13 is heated to generate phase change, and the bonding between the bonding layer 13 and the first layer structure 11 and the second layer structure 12 is released.

Calculating the intrinsic absorption long wave limit of the laser beam according to the forbidden bandwidth of the material of the bonding layer 13; and then, the wavelength of the final laser beam can be determined according to the intrinsic absorption long wave limit of the laser beam, so that the proper laser wavelength can be determined quickly, the difficulty of determining the laser wavelength is simplified, the workload is reduced, and the cost is reduced. When the bonding layer 13 is scanned by the laser beam with the finally determined wavelength, the light absorption efficiency of the bonding layer 13 can be ensured in a larger interval, and then the bonding layer 13 can be heated to a phase change state in a shorter time, so that the bonding between the bonding layer 13 and the first layer structure 11 and the second layer structure 12 is rapidly released, the rapid bonding is facilitated, and the bonding efficiency is improved. The above steps will be described in detail with reference to the accompanying drawings.

First, referring to fig. 1 and 3, the member to be unbonded is held on the stage 10, and the first layered structure 11 is in contact with the stage 10. As shown in fig. 3, the stage 10 serves as a support structure for holding a member to be debonded thereon. When provided, a stage body having a support end surface for contacting the first layer structure 11 may be provided as the stage 10. And a plurality of air suction holes can be arranged on the supporting end surface of the object stage 10, and the plurality of air suction holes are adsorbed on the surface of the first layer structure 11 in the bonding piece to be debonded so as to fix the first layer structure 11 on the object stage 10. Of course, other fastening means capable of holding the first layer structure 11 thereon may also be used.

Next, referring to fig. 1, a laser system for generating a laser beam is provided. And the laser system can also focus the generated laser beam on the bonding layer 13 of the piece to be bonded so as to heat the bonding layer 13, so that the material of the bonding layer 13 is converted from a bonding solid state into a non-bonding state or a melting state, a gas state or a plasma state with smaller bonding force and the like, the bonding between the bonding layer 13 and the first layer structure 11 and the second layer structure 12 is released, and the bonding between the first layer structure 11 and the second layer structure 12 is realized. In setting up the laser system, referring to fig. 3, the laser system may comprise a laser 21, the laser 21 being arranged to generate a laser beam. A focusing lens 22 may be further disposed downstream of the laser 21, and the focusing lens 22 is configured to receive the laser beam and focus the laser beam on the bonding layer 13. Specifically, when the focusing lens 22 is provided, a plano-convex lens or a cylindrical lens may be used as the focusing lens 22. In addition, referring to fig. 3, a set of galvanometer system 23 may be further provided, and the galvanometer system 23 is used for controlling the focus of the laser beam to scan on the bonding layer 13 so as to perform pyrolytic bonding on the whole bonding layer 13. A galvanometer system 23 is provided to control the focus of the laser beam to scan across the bonding layer 13. Specifically, the galvanometer system 23 may be a biaxial galvanometer system 23 or a triaxial galvanometer system 23. It should be noted that the galvanometer system 23 is not necessarily a device, and other implementations may be adopted to control the focal point of the laser beam to scan the bonding layer 13. For example, a stage 10 that is movable in a two-dimensional plane may be employed as an implementation that enables the focal point of the laser beam to scan across the bonding layer 13.

Next, with continued reference to fig. 1, the forbidden band width E of the bonding layer 13 material is determined according to_g0Calculating the intrinsic absorption long wavelength limit of the laser beam according to the following formula:

determined by the above formulaThe wavelength of the laser beam can ensure that the light absorption efficiency of the bonding layer 13 is in a large interval, and then the bonding layer 13 can be heated to a phase change state in a short time, so that the bonding of the bonding layer 13 and the first layer structure 11 and the second layer structure 12 is rapidly released, the rapid bonding is facilitated, and the bonding efficiency is improved. For example, when the material of the bonding layer 13 is silicon (Si), the forbidden bandwidth E of silicon_g0The intrinsic absorption wavelength λ c of the laser beam at this time is about 1.1 μm as found from the above formula 1.12 eV. When the material of the bonding layer 13 is GaAs, the forbidden bandwidth E of GaAs_g0The intrinsic absorption wavelength λ c of the laser beam at this time is about 0.867 μm as found by the above formula 1.43 eV. Both intrinsic absorption wavelengths are now in the infrared region. When the material of the bonding layer 13 is CdS, the forbidden band width E of CdS_g0The intrinsic absorption wavelength λ c of the laser beam at this time is about 0.513 μm as found from the above formula 2.42 eV. In this case, the intrinsic absorption wavelength is limited to the visible light region.

The most prominent light absorption process in semiconductor fabrication is the light absorption of electrons caused by the transition of the valence band to the conduction band, known as intrinsic or fundamental absorption. This absorption is accompanied by the generation of electron-hole pairs, which increase the conductivity of the semiconductor, i.e., produce photoconduction. Obviously, the photon energy causing intrinsic absorption must be equal to or greater than the forbidden band width, i.e. it needs to satisfy:

hν≥hν₀＝E_g

the corresponding wavelength is called the intrinsic absorption wavelength limit. From the above formula, a formula of the intrinsic absorption long wavelength limit of the bonding layer 13 described above in the present application can be obtained.

When the wavelength of the incident light is long enough not to cause interband transitions or the formation of excitons, there is still light absorption in the semiconductor and the absorption coefficient increases with increasing wavelength. This absorption is caused by free carrier transitions within the same energy band and is called free carrier absorption. The absorption of electromagnetic energy by carriers is significantly frequency (or wavelength) dependent. The absorption coefficient of the free carriers satisfies the following relationship:

α∝λ²

where α represents the absorption coefficient of free carriers and λ represents the wavelength of the laser light.

The absorption of light due to the interaction of photons and lattice vibrations, which occurs mainly in the far infrared band, is called lattice vibration absorption.

Next, referring to FIG. 1, the wavelength of the laser beam is determined to be λ 0 according to the intrinsic absorption long wavelength limit of the laser beam, where λ 0 ≦ λ c. Specifically, λ 0 ═ λ c may be selected, so that the light absorption efficiency of the bonding layer 13 is in a relatively large interval, and then the bonding layer 13 can be heated to a state where phase change occurs in a relatively short time, and thus the bonding between the bonding layer 13 and the first layer structure 11 and the second layer structure 12 is rapidly released, which is convenient for rapidly releasing the bonding, and the bonding efficiency is improved. Of course, λ 0 may be any value not greater than 95% λ c, 90% λ c, 85% λ c, 80% λ c, or the like.

In addition, the second layer structure 12 of the bonding material to be debonded has a forbidden band width E_g1In this case, the forbidden band width E of the second layer structure 12 can be set_g1Satisfies the following conditions: e_g1＞E_g0. A laser beam is allowed to pass through the second layer structure 12 relatively easily to heat the bonding layer 13.

Of course, the wavelength of the laser beam may also be made

That is, the wavelength λ 0 of the laser beam at this time satisfies the following relationship:

the laser beam transmitted through the second layer structure 12 can have less energy loss, so that the second layer structure 12 can be prevented from being overheated, and the efficiency of heating the bonding layer 13 can be improved.

Next, referring to fig. 1 and 3, the laser beam is controlled to pass through the second layer structure 12 and then focused on the bonding layer 13.

Next, as shown in fig. 1, the spot of the laser beam is controlled to scan the bonding layer 13, the bonding layer 13 is heated to change the phase, and the bonding between the bonding layer 13 and the first layer structure 11 and the second layer structure 12 is released. In order to facilitate subsequent separation between the two layer structures by stretching the first layer structure 11 and the second layer structure 12 in a direction away from each other.

In addition, referring to fig. 4, before controlling the laser beam to be focused on the bonding layer 13 after transmitting through the second layer structure 12, the laser de-bonding method may further include: set up the sucking disc subassembly, this sucking disc subassembly is including adsorbing the sucking disc 30 on second floor structure 12 surface, promptly before seeing through second floor structure 12 with the laser beam, adsorbs sucking disc 30 on second floor structure 12 surface in advance to in the follow-up back of removing bonding between first floor structure 11 and second floor structure 12 need not fixed sucking disc 30, and the very first time is with second floor structure 12 pull-up, makes and separates between first floor structure 11 and the second floor structure 12. The material of the suction cup 30 can also be set to have a forbidden band width E_g2Wherein E is_g2＞E_g0To facilitate the laser beam's penetration through the chuck 30 and also to reduce the energy loss of the laser beam as it penetrates through the chuck 30 material. At this time, the controlling of the laser beam to pass through the second layer structure 12 and then focus on the bonding layer 13 specifically includes: the laser beam is controlled to pass through the suction cup 30 and the second layer structure 12 from top to bottom in sequence and then is focused on the bonding layer 13. Through adsorbing sucking disc 30 on second layer structure 12 surface earlier, later see through sucking disc 30 and second layer structure 12 by the laser beam from the top down in proper order after, focus on separating bonding layer 13, thereby after the light spot scanning of laser separates bonding layer 13 whole or partial region, need not to remove and fixed suction disc 30, can pull suction disc 30 at the very first time and make first layer structure 11 and second layer structure 12 separate, thereby shorten the laser light spot scanning and end to the interval time of upwards pulling between the second layer structure 12, prevent the interval time overlength, and lead to the bonding layer 13 after being heated to solidify and take place to bond once more, thereby reduce the degree of difficulty of peeling off.

Of course, the forbidden band width E of the material of the suction cup 30 can be used_g2Greater than or equal to the forbidden band width E of the material of the second layer structure 12_g1. Specifically, the forbidden band width E of the material of the suction cup 30 can be set_g2Equal to the forbidden bandwidth E of the material of the second layer structure 12_g1(ii) a Or the forbidden band width E of the material of the suction cup 30_g2Is larger than the forbidden band width E of the material of the second layer structure 12_g1To reduce the energy loss of the laser beam when the laser beam passes through the chuck 30 and the second layer structure 12.

Referring to fig. 4 and 5, the suction cup assembly may further include a stretching mechanism 40 connected to the suction cup 30 for pulling the second layer structure 12 upward with a gap between the second layer structure 12 and the first layer structure 11, thereby completely separating them. At this time, the spot of the laser beam is controlled to scan the bonding layer 13, so that the bonding layer 13 is heated to generate a phase change, and the bonding between the bonding layer 13 and the first layer structure 11 and the second layer structure 12 can be released as follows:

firstly: controlling a light spot of the laser beam to scan a first area of the bonding layer 13, heating the bonding layer 13 in the first area to generate phase change, and removing the bonding of the bonding layer 13 in the first area with the first layer structure 11 and the second layer structure 12; wherein the first region is a partial region of the bonding layer 13;

thereafter, the stretching mechanism 40 is controlled to pull the suction cups 30 upward to separate the first layer structure 11 and the second layer structure 12 at a position coinciding with the first region.

Still later, the spot of the laser beam is sequentially controlled to scan the second to nth areas of the bonding layer 13, and after scanning one area, the stretching mechanism 40 is controlled to pull up the chuck 30 so that the first layer structure 11 and the second layer structure 12 are separated at a position overlapping the one area just scanned. Wherein the first to nth regions constitute the entire region of the bonding layer 13.

After the light spot of the laser scans the partial area of the bonding layer 13, the second layer structure 12 is stretched, so that the two layer structures are separated at the position where the partial areas coincide, the time interval between the light spot scanning and the stretching of the second layer structure 12 is shortened, the bonding layer 13 in the partial area which is just heated can be prevented from being solidified more safely, the laser bonding is removed while the sucking disc 30 is pulled to separate, the phenomenon that the two layer structures are bonded again due to the fact that the bonding material in a molten state is cooled and solidified again can be prevented from occurring more safely, and the peeling difficulty is further reduced.

In determining the first layer structure 11 and the second layer structure 12, the first layer structure 11 may be a wafer, and the second layer structure 12 may be a circular substrate, i.e., a wafer is fixed on the stage 10, and a laser beam is transmitted through the substrate. So as to reduce the difficulty of peeling the wafer and the substrate in the laser bonding process. Meanwhile, the laser beam is prevented from penetrating through the wafer, and the influence of the laser beam on the electrical performance of the microelectronic device on the wafer can be prevented.

When the two layer structures are the wafer and the substrate, respectively, referring to fig. 8, each of the first to N-1 th regions may be a circular ring region, and the nth region may be a circular region. And the first region to the nth region are sequentially arranged from the outer ring to the inner ring of the bonding layer 13. So as to facilitate the diffusion of the gaseous or plasma species generated during the laser debinding process out of the two layer structure. Specifically, the laser system controls the focal point of the laser beam to scan from the outer circle of the bonding layer 13 to the inner circle in sequence in a concentric circle. So as to facilitate the diffusion of the gaseous or plasma species generated during the laser debinding process out of the two layer structure. That is, the focus of the laser beam is focused on the outermost circle of the bonding layer 13 first, and the focus of the laser beam is controlled to scan the outermost circle for one circle, so that the outermost circle of the bonding layer 13 is thermally debonded. And then, gradually scanning step by step from the outer ring to the inner ring in sequence, so that the focus of the laser beam is in a concentric circle shape and is sequentially scanned from the outer ring of the bonding layer 13 to the inner ring of the bonding layer 13, thereby completing the bonding resolution of the whole bonding layer 13. When the inner ring is subjected to debonding, the outer ring is already subjected to debonding to form a molten state, a gaseous state or a plasma state substance, so that the bonding materials in the molten state, the gaseous state or the plasma state and the like generated in the debonding process of the inner ring can overflow outwards. At this time, each circle region is one of the first region to the N-1 region, and the most central circular region is the Nth region.

After the laser beam has performed the debonding on one of the circles of the bonding layer 13, the stretching mechanism 40 is controlled to pull up the suction cup 30, so as to separate the positions of the first layer structure 11 and the second layer structure 12 coinciding with the one circle of the bonding layer, and when the scanning and separating manner is adopted, the partial region may be an annular region in the concentric circle scanning process of the focal point of the laser beam. So that the suction cup 30 is pulled to separate the two layer structures in a circular area. Of course, it is also possible to perform the separating operation at a position on the first layer structure 11 and the second layer structure 12 coinciding with a larger circular area, after the laser beam has continuously scanned the larger circular area consisting of at least two adjacent turns. At this time, at least two adjacent circles of areas swept by the laser beam are one of the first area to the N-1 th area, and the most central circular area is the Nth area.

When the suction cup 30 is disposed, the suction cup 30 may have an absorption end surface 31 absorbed on the surface of the second layer structure 12, and when in use, the absorption end surface 31 is closely attached to the second layer structure 12 to absorb the second layer structure 12. Referring to fig. 6 and 7, a plurality of circles of adsorption channels 32 may be concentrically arranged on the adsorption end surface 31. That is, each circle of the adsorption channel 32 is a circular ring, and a convex end surface is arranged between two adjacent circles of the adsorption channels 32 so as to be attached to the surface of the second layer structure 12. The suction disc 30 sucks the partial annular area of the second layer structure 12 through the negative pressure generated in each circle of suction channel 32, and then the drawing mechanism 40 drives the suction disc 30 to move upwards a little, so that the partial annular area which is just bonded in the two layer structures generates a gap and is separated, and the suction force with the same size is applied to the surface of the second layer structure 12 in the same annular area. In determining the number of the suction channels 32, the number of the suction channels 32 may be 5, 6, 7, 10, 15, 20, etc., depending on the size of the wafer.

In addition, each adsorption passage 32 may be provided with an air valve for controlling the negative pressure in the corresponding adsorption passage 32 so as to adjust the suction force on the surface of the second layer structure 12 to different circular areas. In particular, referring to fig. 4, when the laser beam scans from the outer circle to the inner circle in sequence, the negative pressure in the suction channel 32 may be increased from the outer circle to the inner circle in sequence, so that when the drawing mechanism 40 draws the suction cup 30, the second layer structure 12 may be subjected to a local warping operation from the outer circle to the inner circle in sequence, and the second layer structure 12 and the first layer structure 11 may be separated from the outer circle to the inner circle in sequence. Until the laser beam scans the innermost circle of the bonding layer 13, the stretching mechanism 40 can drive the second layer structure 12 to move upwards, so as to realize complete separation between the second layer structure 12 and the first layer structure 11.

When provided, the chuck 30 can be made of the same material as the substrate to facilitate selection of the laser wavelength and control of the laser transmission through the chuck and the substrate. Specifically, the material of the chuck 30 and the substrate may be quartz, that is, the chuck 30 is a quartz disk and the substrate is a quartz substrate, so as to prevent the chuck 30 and the substrate from affecting the laser transmittance. Of course, the materials of the chuck 30 and the substrate are not limited to the same material, and any arrangement that allows the laser beam to sequentially pass through the chuck 30 and the substrate is within the scope of the present application. And when the chuck 30 and the substrate are made of the same material, the arrangement is not limited to the above-described arrangement in which both are made of quartz material.

Of course, the suction cup 30 may be disposed in other ways, for example, referring to fig. 9 to 14, the suction cup 30 may be shaped like a disk so as to suck the disk-shaped key to be released. The suction pad 30 has a suction end surface 31 and a connection end surface 33 opposed to each other, and as shown in fig. 9, the upper surface of the suction pad 30 is the connection end surface 33, and the lower surface of the suction pad 30 is the suction end surface 31. Wherein the absorption end face 31 is used for absorbing on the surface of the second layer structure 12, and the connection end face 33 is used for connecting the stretching mechanism 40 so as to lift a partial area of the suction cup 30 upwards. As shown in fig. 9 to 12, the suction end surface 31 of the suction cup 30 is divided into at least three suction areas 34, and the three suction areas 34 include a circular suction area 34 located at the center of the suction cup 30 and at least two circular suction areas 34 arranged in sequence from the circular suction area 34 to the outside. That is, at least three absorption regions 34 are provided on the end surface of the suction cup 30, the at least three absorption regions 34 include a circular absorption region 34 located at the center of the suction cup 30, and at least two circular absorption regions 34 are further provided, and the at least two circular absorption regions 34 are sequentially arranged from inside to outside from the central circular absorption region 34, so that when the end surface of the suction cup 30 is absorbed on the surface of the second layer structure 12, the at least three absorption regions 34 on the absorption end surface 31 are absorbed on the surface of the second layer structure 12. When the number of the adsorption regions 34 is determined, the number of the adsorption regions 34 shown in fig. 9 is 4, and includes a circular adsorption region 34 located at the center and 3 circular adsorption regions 34 arranged in sequence from inside to outside. It should be understood that the number of the divided adsorption regions 34 on the adsorption end face 31 is not limited to the arrangement of 4 as shown in fig. 9, and besides, the number of the adsorption regions 34 on the adsorption end face 31 may be any value not less than 3, such as 3, 5, 6, 8, 12, 18, etc.

Referring to fig. 8, 9 and 10, the number of suction areas 34 that can be defined on the suction end surface 31 of the suction pad 30 is also N, and N areas from the first area to the N-th area on the bonding layer 13 correspond to N suction areas 34 on the suction end surface 31, that is, each of the first area to the N-th area on the bonding layer 13 corresponds to one suction area 34 on the suction end surface 31. An absorbing region 34 on the absorbing end surface 31 and a region corresponding to the absorbing region 34 on the bonding layer 13 can be opposite to each other, so that after the absorbing region 34 is debonded by laser on the bonding layer 13, the suction cup at the absorbing region 34 is pulled upwards, and the wafer and the substrate are separated at the absorbing region 34, thereby simplifying the peeling difficulty.

In addition, in determining the suction force of each adsorption area 34 adsorbing the corresponding position of the second layer structure 12, referring to fig. 13, at least three vacuum pumps 35 may be provided, the at least three vacuum pumps 35 correspond to the at least three adsorption areas 34 one by one, and each vacuum pump 35 is used for adjusting the suction force of the corresponding adsorption area 34. As shown in fig. 13, 4 vacuum pumps 35 are provided, and each vacuum pump 35 corresponds to one adsorption region 34. That is, each suction area 34 is provided with a vacuum extractor 35 to individually adjust the suction force of the corresponding suction area 34, so that the suction forces generated by different suction areas 34 are different, and when one stretching mechanism 40 lifts the suction cup 30 at the position corresponding to the suction area 34, the suction force of the suction area 34 is increased or decreased according to the difficulty of lifting the suction cup 30 at the position corresponding to the suction area 34. For example, the suction force of at least three suction areas 34 may be increased from the outer circumference to the inner circumference of the suction end surface 31, so that the suction force generated by the suction area 34 near the center is larger and the suction force generated by the suction area 34 near the edge is smaller. When the suction cups 30 close to the suction areas 34 at the edge positions are lifted by the stretching mechanism 40, the areas of the suction areas 34 at the edge positions are larger, and the lever of the suction force is larger, so that the lifting difficulty is smaller. The area of the suction area 34 near the center is smaller, and the lever for suction is smaller, so that the lifting difficulty is higher. By adopting the arrangement mode that the suction force of the suction area 34 near the central position is larger, and the suction force of the suction area 34 near the edge position is smaller, the suction disc 30 can be prevented from being separated from the second layer structure 12 due to the fact that the suction force between the suction area 34 and the second layer structure 12 is too small when the suction area 34 positioned at the inner ring is lifted by the corresponding stretching mechanism 40.

In addition, referring to fig. 12, a plurality of circles of the adsorption channels 32 may be concentrically arranged on the adsorption end surface 31. That is, each circle of the adsorption channel 32 is a circular ring, and a convex end surface is arranged between two adjacent circles of the adsorption channels 32 so as to be attached to the surface of the second layer structure 12. The number of passes 32 in each adsorption zone 34 may be 1, 2, 3, 5, 10, etc. The suction disc 30 sucks the partial annular area of the second layer structure 12 through the negative pressure generated in each circle of suction channel 32, and then the drawing mechanism 40 drives the suction disc 30 to move upwards a little, so that the partial annular area which is just bonded in the two layer structures generates a gap and is separated, and the suction force with the same size is applied to the surface of the second layer structure 12 in the same annular area.

Referring to fig. 13, a stretching mechanism 40 is also provided to raise the suction cups 30 of the different suction areas 34 to separate the two layer structures at the different suction cup 30 areas. Specifically, the number of the groups of the stretching mechanisms 40 is at least three, the at least three groups of stretching mechanisms 40 correspond to the at least three adsorption areas 34 one by one, and each group of stretching mechanisms 40 is used for pulling up the corresponding adsorption area 34 after the bonding layer 13 at the position corresponding to the adsorption area 34 is heated by laser to undergo phase change, so that the first layer structure 11 and the second layer structure 12 are separated at the position corresponding to the adsorption area 34. As shown in fig. 13, the number of the sets of the stretching mechanisms 40 is 4, the 4 sets of stretching mechanisms 40 respectively correspond to 4 suction areas 34 on the suction end surface 31, each suction area 34 corresponds to one set of stretching mechanisms 40, and each set of stretching mechanisms 40 is used for lifting the suction cup 30 at the position corresponding to the suction area 34 so as to separate the two layer structures at the position corresponding to the suction area 34. Here, the two-layer structure at the position of each adsorption region 34 refers to a portion of the second-layer structure 12 adsorbed by each adsorption region 34 and a portion of the first-layer structure 11 which is vertically opposed to the portion of the second-layer structure 12. By dividing the suction end surface 31 of the suction cup 30 into at least three suction areas 34 and providing a set of stretching mechanisms 40 for each suction area 34, a tensile force can be applied to a certain suction area 34 of the suction cup 30 individually. In the laser de-bonding process, the corresponding adsorption area 34 of the sucker 30 can be lifted immediately after the bonding layer 13 area of the laser scanning part is scanned, so that the two layer structures at the position of the adsorption area 34 are separated, and therefore, the sucker 30 does not need to be applied with pulling force after the whole bonding layer 13 is scanned with laser, the time from the scanning of the bonding layer 13 of the part area to the separation of the two layer structures of the part area is shortened, the bonding layer 13 in a molten state is prevented from being heated by the laser to be condensed and bonded again, so that a larger pulling force is not required to be applied to the sucker 30, and the stripping difficulty is reduced; and the bonding layer 13 does not need to be scanned for multiple times, so that the stripping time is shortened, and the stripping efficiency is improved.

In addition, in providing each of the stretching mechanisms 40, referring to fig. 10, the stretching mechanism 40 corresponding to the circular suction region 34 located at the central position and the stretching mechanism 40 corresponding to the circular suction region 34 located at the non-central position may be provided in different structures. Specifically, each of the at least two sets of stretching mechanisms 40 corresponding to the at least two annular adsorbing areas 34 may include at least three pull rods 41 and one lifting mechanism 44. Namely, the stretching mechanism 40 corresponding to each circular ring-shaped adsorption area 34 comprises at least three pull rods 41, and each pull rod 41 in the three pull rods 41 is connected with the connecting end surface 33 of the suction cup 30. As shown in fig. 10, the stretching mechanism 40 corresponding to each circular ring-shaped adsorption area 34 includes 3 pull rods 41, and it should be noted that the arrangement of the 3 pull rods 41 shown in fig. 9 is not limited in the stretching mechanism 40 corresponding to each circular ring-shaped adsorption area 34, and in addition, 4 pull rods 41, 5 pull rods 41, 6 pull rods 41, and the like may be used. The number of the pull rods 41 in the stretching mechanisms 40 corresponding to different circular ring-shaped adsorption areas 34 may be set in the same manner as shown in fig. 10, or the number of the pull rods 41 in the stretching mechanisms 40 corresponding to different circular ring-shaped adsorption areas 34 may be different. Specifically, the number of the tension rods 41 in the tension mechanism 40 located at the edge may be larger, and the number of the tension rods 41 in the tension mechanism 40 located near the center may be smaller. Or, the number of the tension rods 41 in the tension mechanism 40 located at the edge may be small, and the number of the tension rods 41 in the tension mechanism 40 located near the center may be large. Referring to fig. 10, the connection points of all the pull rods 41 and the connection end surfaces 33 in the same group of stretching mechanisms 40 are circumferentially and uniformly distributed around the center of the suction cup 30, that is, the connection points of all the pull rods 41 and the suction end surfaces 31 in the stretching mechanisms 40 corresponding to each circular ring-shaped suction area 34 are circumferentially and uniformly distributed around the center of the suction cup 30, so as to uniformly pull the suction cup 30 at each circular ring-shaped suction area 34. The lifting mechanism 44 is used for lifting at least three pull rods 41 along the axial direction of the suction cup 30, that is, the pulling force exerted on each pull rod 41 is parallel to the axial direction of the suction cup 30, so that the pulling direction of the pull rod 41 is parallel to the separation direction of the two layer structures at the separation of the suction areas 34, and the difficulty of separating the two layer structures at the position of each suction area 34 is simplified. The uniform application of tensile force to each circular ring-shaped adsorption area 34 is facilitated, and the second layer structure 12 is prevented from being deformed in the circumferential direction of each circular ring-shaped adsorption area 34.

With continued reference to fig. 10, the connection points between the at least three pull rods 41 and the connection end surface 33 in each set of stretching mechanisms 40 may be located in the circular ring-shaped adsorption region 34 corresponding to the set of stretching mechanisms 40, that is, the connection points between all the pull rods 41 and the connection end surface 33 in the stretching mechanism 40 corresponding to each adsorption region 34 are located at the position corresponding to the adsorption region 34, so that the connection points between all the pull rods 41 and the connection end surface 33 in the set of stretching mechanisms 40 are closer to the circular ring-shaped adsorption region 34 corresponding to the set of stretching mechanisms 40, thereby improving the lifting efficiency and effect. Of course, it is within the scope of this patent to not limit the arrangement described above so long as it facilitates separation of the two layer structures in each adsorption zone 34.

As shown in fig. 10, when the stretching mechanism 40 corresponding to the central circular suction area 34 is provided, a group of stretching mechanisms 40 corresponding to the circular suction area 34 includes a central rod 41 and a lifting mechanism 44. The connection point between the center rod 41 and the suction cup 30 is located at the center of the connection end surface 33, and the lifting mechanism 44 is used for lifting the center rod 41 in the axial direction of the suction cup 30. Namely, a central pull rod 41 is arranged in the circular adsorption area 34 to serve as a tensile connecting piece, the central pull rod 41 is arranged in the center, and the sucker 30 is pulled from the center of the circular adsorption area 34, so that the defect that the second layer structure 12 is deformed inconsistently in the circumferential direction of the circular adsorption area 34 is overcome. It should be noted that the arrangement of the stretching mechanism 40 corresponding to the circular absorption area 34 is not limited to the arrangement of one central pull rod 41 shown above, and other arrangements may be adopted. For example, the stretching mechanism 40 corresponding to the circular suction area 34 at the center position may be arranged in the same manner as the stretching mechanism 40 corresponding to the circular suction area 34 described above. That is, the stretching mechanism 40 corresponding to the circular suction area 34 also has at least three pull rods 41, and the at least three pull rods 41 are uniformly distributed in the circumferential direction around the center of the suction cup 30.

In addition, referring to fig. 10, in at least three sets of stretching mechanisms 40, the connecting point between the pull rod 41 and the connecting end surface 33 in any two adjacent sets of stretching mechanisms 40 may be gradually decreased from the edge of the suction cup 30 to the center of the suction cup 30 in the radial direction of the suction cup 30. It should be noted that the step of the connection point between the pull rod 41 and the connecting end surface 33 in the radial direction of the suction cup 30 in the two adjacent sets of the stretching mechanisms 40 refers to the distance between the connection point between the pull rod 41 and the connecting end surface 33 in the radial direction of the suction cup 30 in the two adjacent sets of the stretching mechanisms 40. The larger the distance is, the larger the step is, the larger the distance in the radial direction of the suction cup 30 between the connecting point between the pull rod 41 and the connecting end surface 33 in the two adjacent groups of the stretching mechanisms 40 is represented; conversely, the smaller the distance, the smaller the step, which means the smaller the distance between the connecting point between the pull rod 41 and the connecting end face 33 in the two adjacent sets of stretching mechanisms 40 in the radial direction of the suction cup 30. The radial step of the connection point between the pull rod 41 and the connection end surface 33 in any two adjacent sets of the stretching mechanisms 40 in the suction cup 30 is gradually reduced from the edge of the suction cup 30 to the center of the suction cup 30, which means that the radial step of the connection point between the pull rod 41 and the connection end surface 33 in two adjacent sets of the stretching mechanisms 40 near the edge is larger, and the radial step of the connection point between the pull rod 41 and the connection end surface 33 in two adjacent sets of the stretching mechanisms 40 near the center is smaller in the suction cup 30, so as to counteract the influence of the difficulty in deformation of the inner ring relative to the outer ring of the second layer structure 12, and make the lifting height of each set of the stretching mechanisms 40 to the corresponding adsorption area 34 more consistent.

Referring to fig. 14, each of the at least two sets of stretching mechanisms 40 corresponding to the at least two annular absorption areas 34 may further include a support 42, the support 42 includes at least three arms 43, and the at least three arms 43 correspond to the at least three pull rods 41 in the corresponding set of stretching mechanisms 40 one by one. Wherein each support arm 43 is connected with a corresponding pull rod 41, and the axial direction of each pull rod 41 is parallel to the axial direction of the suction cup 30. Namely, a bracket 42 is further arranged in the stretching mechanism 40 corresponding to each circular ring-shaped adsorption area 34, so that all the pull rods 41 in the stretching mechanism 40 are connected into a whole structure. Specifically, the lifting mechanism 44 lifts all the pull rods 41 in the stretching mechanism 40 by connecting all the pull rods 41 in the stretching mechanism 40 to the support arm 43 on the support 42, so as to apply a relatively uniform pulling force to all the pull rods 41 in the same set of stretching mechanisms 40.

Of course, when there is only one central pull rod 41 in the stretching mechanism 40 corresponding to the circular absorption area 34 located at the central position, the bracket 42 may not be provided, and the lifting mechanism 44 may directly lift the central pull rod 41. When the stretching mechanism 40 corresponding to the circular adsorption area 34 adopts the same setting mode as the stretching mechanism 40 of the circular adsorption area 34 and also includes at least three pull rods 41, the plurality of pull rods 41 can be connected into an integrated structure by adopting the above-mentioned support 42 mode, so that the lifting mechanism 44 can lift the plurality of pull rods 41 together, and all the pull rods 41 in the same group of stretching mechanisms 40 are exerted with uniform pulling force.

When the lifting mechanism 44 is provided, with continued reference to fig. 14, the lifting mechanism 44 may be a rack and pinion lifter, the rack of the rack and pinion lifter is fixedly connected to the arm 43 or the central pull rod 41, and the transmission direction of the rack coincides with the axial direction of the suction cup 30. To simplify the construction of the lifting mechanism 44. It should be understood that the lifting mechanism 44 is not limited to a rack and pinion lifter arrangement, and other arrangements may be used. For example, a lead screw lifter can be used as the lifting mechanism 44, and a lead screw of the lead screw lifter is connected with the bracket 42 or the central pull rod 41, so that the pull rod 41 and the suction cup 30 can be lifted.

Calculating the intrinsic absorption long wave limit of the laser beam according to the forbidden bandwidth of the material of the bonding layer 13; and then, the wavelength of the final laser beam can be determined according to the intrinsic absorption long wave limit of the laser beam, so that the proper laser wavelength can be determined quickly, the difficulty of determining the laser wavelength is simplified, the workload is reduced, and the cost is reduced. When the bonding layer 13 is scanned by the laser beam with the finally determined wavelength, the light absorption efficiency of the bonding layer 13 can be ensured in a larger interval, and then the bonding layer 13 can be heated to a phase change state in a shorter time, so that the bonding between the bonding layer 13 and the first layer structure 11 and the second layer structure 12 is rapidly released, the rapid bonding is facilitated, and the bonding efficiency is improved.

The above description is only for the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A laser bonding method is used for bonding a to-be-bonded part, wherein the to-be-bonded part comprises a first layer structure and a second layer structure bonded through a bonding layer, and the laser bonding method comprises the following steps:

holding the to-be-debonded bond on an object table, wherein the first layer structure is in contact with the object table;

a laser system arranged to generate a laser beam;

determining the wavelength of the laser beam to be lambda 0 according to the intrinsic absorption long wave limit of the laser beam, wherein lambda 0 is not more than lambda c;

controlling the laser beam to be focused on the bonding layer after penetrating through the second layer structure;

and controlling the light spot of the laser beam to scan on the bonding layer, so that the bonding layer is heated to generate phase change, and the bonding of the bonding layer with the first layer structure and the second layer structure is released.

2. The laser debonding method of claim 1, wherein the second layer of the structural material has a forbidden bandwidth of E_g1Wherein E is_g1＞E_g0。

3. The laser debonding method of claim 2,

wavelength of the laser beam

4. The laser de-bonding method of claim 1, wherein before the controlling the laser beam to be focused on the bonding layer after transmitting through the second layer structure, the laser de-bonding method further comprises:

arranging a sucker assembly, wherein the sucker assembly comprises a sucker adsorbed on the surface of the second layer structure; and the forbidden band width of the sucker material is E_g2Wherein E is_g2＞E_g0；

The controlling the laser beam to be focused on the bonding layer after transmitting the second layer structure comprises:

and controlling the laser beam to sequentially pass through the sucker and the second layer structure from top to bottom and then focus on the bonding layer.

5. The laser debonding method of claim 4, wherein the chuck material has a forbidden bandwidth E_g2The forbidden band width E of the second layer structure material is larger than or equal to_g1。

6. The laser debonding method of claim 4, wherein the chuck assembly further comprises a stretching mechanism coupled to the chuck;

the controlling the light spot of the laser beam to scan on the bonding layer to enable the bonding layer to be heated to generate phase change, and the removing the bonding of the bonding layer and the first layer structure and the second layer structure comprises the following steps:

controlling a light spot of the laser beam to scan a first area of the bonding layer, heating the bonding layer of the first area to generate phase change, and removing the bonding of the bonding layer of the first area with the first layer structure and the second layer structure; wherein the first region is a partial region of the bonding layer;

controlling the stretching mechanism to pull the suction cup upwards to separate the first layer structure and the second layer structure at a position coinciding with the first area;

sequentially controlling a light spot of the laser beam to scan second to Nth regions of the bonding layer, and after scanning one region, controlling the stretching mechanism to pull the chuck upward so that the first layer structure and the second layer structure are separated at a position coinciding with the just scanned one region; wherein the first to Nth regions constitute an entire region of the bonding layer.

7. The laser debonding method of claim 6, wherein the first layer structure is a wafer and the second layer structure is a substrate.

8. The laser debonding method of claim 7, wherein each of the first through N-1 regions is a circular ring-shaped region, and the nth region is a circular region;

and the first region to the Nth region are sequentially arranged from the outer ring to the inner ring of the bonding layer.

9. The laser debonding method of claim 7, wherein the chuck and the substrate are both quartz.

10. The laser debonding method of claim 1, wherein the laser system further comprises a galvanometer system;

the controlling of scanning of the light spot of the laser beam on the bonding layer specifically includes: and controlling the galvanometer system to scan the light spot of the laser beam on the bonding layer.