Method for determining the position of a laser generator for debonding

Abstract

The present invention provides a method for determining the position of a laser generator for debonding, which is applied to the debonding process of a stacked structure. The stacked structure is formed by bonding a wafer and a substrate. The method includes: irradiating the first region of the stacked structure with a laser and applying a force to separate the wafer and the substrate in the first region; after the separation of the first region, obtaining the position of the second region after deformation; determining the original optical path based on the original target burst point position corresponding to the second region, the original position of the second region, and the original target position of the laser generator; determining the optical path to be compensated and the position of the burst point to be compensated based on the part of the optical path before entering the substrate before compensation and the position of the second region after deformation; determining the target position of the laser generator based on the part of the optical path after entering the substrate of the optical path to be compensated and the target burst point position of the second region after deformation. The present invention can pre-compensate for the displacement of the burst point caused by the deformation position of the substrate to ensure the accuracy of the burst point position.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor processing technologies, and in particular, to a method for determining the position of a laser generator for debonding. Background Art

[0002] In the field of semiconductor manufacturing processes, it is often necessary to thin the thickness of a single semiconductor wafer. Therefore, it is necessary to perform backside thinning processing (grinding and cutting) on the semiconductor wafer with thickness after loading an integrated circuit. During the processing, a substrate is usually used to temporarily bond (Temporary Bonding) the semiconductor wafer, and the substrate serves as the base of the semiconductor wafer during the processing to protect the semiconductor wafer from being damaged due to thickness thinning during the processing. After the semiconductor wafer is thinned, the semiconductor wafer and the substrate must be debonded (DeBonding). One debonding method is to divide the bonding mechanism formed by bonding the wafer and the substrate into multiple regions, and perform laser irradiation and separation on each region.

[0003] In the process of implementing the present invention, the inventors found that there are at least the following technical problems in the prior art: the separated regions will cause the entire bonding structure to deform, resulting in inaccurate laser burst point positions. Summary of the Invention

[0004] The method for determining the position of a laser generator for debonding provided by the present invention can perform pre-compensation for the burst point displacement caused by the deformation position of the substrate to ensure the accuracy of the burst point position.

[0005] The present invention provides a method for determining the position of a laser generator for debonding, which is applied to the debonding process of a stacked structure. The stacked structure is formed by bonding a wafer and a substrate. The method includes:

[0006] Performing laser irradiation on a first region of the stacked structure and applying a force to separate the wafer and the substrate in the first region;

[0007] After the first region is separated, obtaining the position of a second region after deformation;

[0008] Determining an original optical path based on the original target burst point position corresponding to the second region, the original position of the second region, and the original target position of the laser generator;

[0009] Determining a path to be compensated and a burst point position to be compensated based on the part of the optical path before entering the substrate before compensation and the position of the second region after deformation;

[0010] Determining the target position of the laser generator based on the part of the optical path after entering the substrate of the path to be compensated and the target burst point position of the second region after deformation.

[0011] Optionally, laser irradiating a first region of the stacked structure and applying a force to the wafer and the substrate in the first region for separation includes:

[0012] Adsorbing a transparent suction cup on the substrate;

[0013] Passing laser through the transparent suction cup to irradiate the first region;

[0014] Applying a force to the substrate in the first region through the transparent suction cup to separate the wafer from the substrate.

[0015] Optionally, passing laser through the transparent suction cup to irradiate the first region includes:

[0016] Determining an available wavelength range according to the transmission wavelength of the transparent suction cup and the transmission wavelength of the substrate;

[0017] Passing laser with a wavelength within the available wavelength range through the transparent suction cup to irradiate the first region.

[0018] Optionally, the transparent suction cup has a plurality of force-applying pull rods;

[0019] Applying a force to the substrate in the first region through the transparent suction cup includes:

[0020] Applying a force to the substrate using at least one force-applying pull rod closest to the first region to separate the wafer from the substrate.

[0021] Optionally, applying a force to the substrate in the first region through the transparent suction cup to separate the wafer from the substrate includes:

[0022] Increasing the adsorption force of the transparent suction cup on the first region from a first predetermined value to a second predetermined value;

[0023] Applying a force to the transparent suction cup with a force less than the second predetermined value to separate the wafer from the substrate.

[0024] Optionally, determining the target position of the laser generator according to the part of the light path to be compensated after entering the substrate and the target detonation point position after the second region deforms includes:

[0025] Taking the direction of the part of the light path to be compensated after entering the substrate as the target direction;

[0026] Taking the propagation path along the target direction and passing through the target detonation point position after the second region deforms as the compensated post-incidence light path;

[0027] Determining the compensated pre-incidence light path according to the compensated post-incidence light path and the refractive index of the substrate;

[0028] Determine the target position of the laser generator based on the intersection point of the compensated pre-incident optical path and a plane at a predetermined height.

[0029] Optionally, the first region and the second region are concentric annular regions, and the diameter of the second region is smaller than the diameter of the first region.

[0030] Optionally, the laser beam emitted by the laser generator is a focused laser beam.

[0031] Optionally, determining the target position of the laser generator based on the part of the optical path after it is incident on the substrate to be compensated and the target detonation point position after the second region is deformed includes:

[0032] Determine two opposite generatrices based on the conical space passed through by the part of the optical path after it is incident on the substrate to be compensated;

[0033] Taking the directions corresponding to the two generatrices as directions and using the target detonation point position after the second region is deformed as the intersection point, confirm the two generatrices of the incident part of the compensated optical path;

[0034] Based on the two generatrices of the incident part of the compensated optical path, confirm the two generatrices of the pre-incident part of the compensated optical path;

[0035] Determine the target position of the laser generator based on the two generatrices of the pre-incident part.

[0036] Optionally, the two generatrices are the two generatrices with the largest included angle in the conical space.

[0037] In the technical solution provided by the present invention, since the deformation of the substrate does not affect the optical path before incidence, first, determine the original optical path, and incident the original optical path into the deformed substrate to determine the detonation point position corresponding to the original optical path. Since the target detonation point position will move along with the deformation of the substrate, there will be a certain offset between the detonation point position corresponding to the original optical path and the target detonation point position. Therefore, use the optical path to be compensated to pass through the target detonation point position, and thus reversely determine the propagation path of the optical path. Obviously, the laser generator should be on the propagation path of the optical path. Therefore, the position of the laser generator can be determined based on the propagation path of the optical path. Description of the Drawings

[0038] Figure 1 It is a flowchart of the method for determining the position of the laser generator for debonding in an embodiment of the present invention;

[0039] Figure 2 It is an optical path diagram for determining the original optical path in the method for determining the position of the laser generator for debonding in another embodiment of the present invention;

[0040] Figure 3Optical path diagram for determining the optical path to be compensated in the method for determining the position of the laser generator for debonding according to another embodiment of the present invention;

[0041] Figure 4 Flow chart of wafer and substrate separation in the method for determining the position of the laser generator for debonding according to another embodiment of the present invention;

[0042] Figure 5 Flow chart of laser irradiation in the method for determining the position of the laser generator for debonding according to another embodiment of the present invention;

[0043] Figure 6 Flow chart of wafer and substrate separation in the method for determining the position of the laser generator for debonding according to another embodiment of the present invention;

[0044] Figure 7 Flow chart of determining the target position of the laser generator in the method for determining the position of the laser generator for debonding according to another embodiment of the present invention;

[0045] Figure 8 Flow chart of determining the target position of the laser generator in the method for determining the position of the laser generator for debonding according to another embodiment of the present invention. Detailed implementation manners

[0046] To make the objectives, 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 accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are only a part rather than all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0047] An embodiment of the present invention provides a method for determining the position of a laser generator for debonding. As Figure 1 shown, it is applied to the debonding process of a stacked structure, where the stacked structure is formed by bonding a wafer and a substrate. The method includes:

[0048] Step 100, irradiate a first region of the stacked structure with a laser and apply a force to separate the wafer and the substrate in the first region;

[0049] In some embodiments, to avoid heat dissipation during the processes of laser irradiation and separation by applying a force with a suction cup in the stacked structure, the stacked structure is divided into multiple regions, and local irradiation and separation by applying a force are performed on each region. Thus, since the time required for irradiating a local region is short, heat dissipation during the irradiation process can be avoided, and the separation effect can be improved. However, when separating the previous region, deformation will occur in other regions of the electrode plate, resulting in an offset of the explosion point during the subsequent irradiation process.

[0050] Step 200, after separating in the first region, obtain the position of the deformed second region;

[0051] In some embodiments, as Figures 2-3 shown, the original position of the electrode plate is L0, the deformed position is L5, and the included angle between the two is α.

[0052] Step 300, determine the original optical path according to the original target detonation point position corresponding to the second region, the original position of the second region, and the original target position of the laser generator;

[0053] In some embodiments, as Figures 2-3 shown, the original target detonation point position is Q, the original position of the second region is the position of L0, and together with the original target position of the laser generator, the original optical path can be determined, that is, the positions of L1 and L3, and the refracted paths of L1 and L3.

[0054] Step 400, determine the optical path to be compensated and the position of the detonation point to be compensated according to the part of the optical path before entering the substrate before compensation and the position of the deformed second region;

[0055] In some embodiments, as Figures 2-3 shown, L5 is the deformed position, L2 and L4 are the optical paths to be compensated, and E is the position of the detonation point to be compensated. The position of the detonation point to be compensated can be determined by refracting the original optical path through the deformed second region.

[0056] Step 500, determine the target position of the laser generator according to the part of the optical path after the optical path to be compensated enters the substrate and the target detonation point position of the deformed second region.

[0057] In some embodiments, move the Q point along the deformation direction of the second region to obtain the target detonation point position Q' (not shown in the figure) of the deformed second region; move L2 and L4 so that the E point moves to the Q' (not shown in the figure) point, thereby determining the actual laser optical path and determining the target position of the laser generator according to the actual laser optical path.

[0058] In the above calculation process, the mathematical relationships between the positions of each point and each line are as follows:

[0059] Taking the original horizontal plane, i.e., L0, as the X-axis, and the middle position between the original two incident points A and B as the zero point to establish a coordinate system, where the distance between AB is d, and the incident points after deformation are C and D respectively. The distance between the origin and the inclined plane L5 in the Y direction is m. It is incident from the air with a refractive index of n1 into the substrate with a refractive index of n2.

[0060] Where the original incident angle is θ, then:

[0061] Coordinates of point A Coordinates of point B

[0062] According to the law of refraction, the slopes of the straight lines L1, L2, L3, L4, and L5 can be calculated respectively as follows:

[0063] k1 = -cotθ;

[0064]

[0065] k3 = cotθ;

[0066]

[0067] k5 = tanα;

[0068] Equation of the straight line L1:

[0069] Equation of the straight line L5: y = k5x + m;

[0070] Obtain the coordinates of point C based on L1 and L5

[0071] Obtain the equation of the straight line L2 based on point C and k2:

[0072] Equation of the straight line L3:

[0073] Equation of the straight line L5: y = k5x + m;

[0074] Obtain the coordinates of point D based on L3 and L5

[0075] Obtain the equation of the straight line L4 based on point D and k4:

[0076] Obtain the coordinates of point E by the straight lines L2 and L4, then the coordinates of the focal point E after the incident surface is tilted

[0077] Coordinates of the original focal point Q

[0078] In the technical solution provided in this embodiment, since the deformation of the substrate does not affect the optical path before incidence, therefore, first determine the original optical path, and incident the original optical path into the deformed substrate to determine the position of the explosion point corresponding to the original optical path. Since the position of the target explosion point will move along with the deformation of the substrate, there will be a certain offset between the position of the explosion point corresponding to the original optical path and the target explosion point. Therefore, the compensation optical path to be used passes through the target explosion point to reversely determine the propagation path of the optical path. Obviously, the laser generator should be on the propagation path of the optical path. Therefore, the position of the laser generator can be determined based on the propagation path of the optical path.

[0079] As an alternative embodiment, as Figure 4 shown, the laser irradiation of the first region of the stacked structure and applying a force to separate the wafer and the substrate in step 100 includes:

[0080] Step 110, adsorb the transparent suction cup on the substrate;

[0081] In some embodiments, the transparent suction cup is adsorbed on the substrate. In the subsequent process, the laser passes through the transparent suction cup to irradiate the bonding glue, causing the bonding glue to undergo a phase change. Subsequently, the transparent suction cup can be used to apply a force, making the irradiation process and the force application process seamlessly connected and reducing heat loss.

[0082] Step 120, pass the laser through the transparent suction cup to irradiate the first region with the laser;

[0083] In some embodiments, as described in step 110, the laser needs to pass through the transparent suction cup to irradiate the first region. Therefore, the laser wavelength needs to be within the transmission wavelength range of the material of the transparent suction cup.

[0084] Step 130, apply a force to the substrate in the first region through the transparent suction cup to separate the wafer and the substrate.

[0085] In some embodiments, after the laser irradiation is completed, the bonding glue has lost its function of bonding the wafer and the substrate, or its bonding effect has been reduced to a low enough level. At this time, applying a force to the wafer and the substrate can achieve the separation of the first region.

[0086] As an alternative embodiment, as Figure 5 shown, the laser irradiation of the first region with the laser through the transparent suction cup in step 120 includes:

[0087] Step 121, determine the available wavelength range according to the transmission wavelength of the transparent suction cup and the transmission wavelength of the substrate;

[0088] In some embodiments, after the transparent suction cup is adsorbed on the substrate, during the process of irradiating with a laser, it is necessary to irradiate the bonding glue with the laser through the transparent suction cup and the substrate. Therefore, it is necessary to make the laser wavelength within the range of the projection wavelength of the transparent suction cup and the projection wavelength of the substrate.

[0089] Step 122, irradiate the first area with a laser whose wavelength is within the available wavelength range through the transparent suction cup.

[0090] In some embodiments, the laser within the available wavelength range can smoothly pass through the transparent suction cup and the substrate without being absorbed. Thus, the energy of the laser can be absorbed by the bonding glue to the greatest extent.

[0091] As an alternative embodiment, the transparent suction cup has a plurality of force - applying pull rods;

[0092] The step of applying a force to the substrate in the first area by the transparent suction cup in step 130 includes:

[0093] Apply a force to the substrate using at least one force - applying pull rod closest to the first area to separate the wafer and the substrate.

[0094] As an alternative embodiment, as Figure 6 shown, the step of applying a force to the substrate in the first area by the transparent suction cup in step 130 to separate the wafer and the substrate includes:

[0095] Step 131, increase the adsorption force of the transparent suction cup on the first area from a first predetermined value to a second predetermined value;

[0096] In some embodiments, since during the laser irradiation process, the transparent suction cup only needs to adsorb and fix the substrate and does not need to apply a pulling force, a relatively low adsorption force can be used. During the force - applying process, a larger adsorption force is required to ensure that the pulling force can be transmitted to the substrate. The first predetermined value can be less than the adsorption force provided when the exhaust pipe of the transparent suction cup is not fully opened. For example, the adsorption force provided when the exhaust pipe is opened by 30% or 50%. The second predetermined value can be an adsorption force greater than the first predetermined value. For example, it can be the adsorption force provided when the exhaust pipe is opened by 80% or 100%.

[0097] Step 132, apply a force to the transparent suction cup with a force less than the second predetermined value to separate the wafer and the substrate.

[0098] In some embodiments, in order to enable the suction cup to conduct the pulling force of the force - applying pull rod to the substrate, it is necessary to ensure that the applied pulling force is less than the second predetermined value to avoid separating the suction cup from the substrate when applying the pulling force, thus resulting in failure to apply a pulling force to the substrate.

[0099] As an alternative embodiment, as Figure 7 shown, determining the target position of the laser generator according to the part of the optical path to be compensated after entering the substrate and the target detonation point position after the second region deforms in step 500 includes:

[0100] Step 510, taking the direction of the part of the optical path to be compensated after entering the substrate as the target direction;

[0101] In some embodiments, for the same incident angle and the same propagation medium, after incidence, its propagation direction is fixed. Therefore, in this step, taking the direction of the optical path to be compensated as the target direction can determine the direction of the optical path incident at any position.

[0102] Step 520, taking the propagation path along the target direction and passing through the target detonation point position after the second region deforms as the compensated optical path after incidence;

[0103] In some embodiments, the target detonation point position after the second region deforms is the actual detonation point position to be irradiated. Therefore, the propagation path of the optical path needs to pass through this detonation point position. Given a determined direction and a point on the path, a unique optical path propagation path can be determined.

[0104] Step 530, determining the compensated optical path before incidence according to the compensated optical path after incidence and the refractive index of the substrate;

[0105] In some embodiments, since the optical path is reversible, therefore, by emitting the compensated optical path after incidence out of the substrate, the optical path before incidence can be determined.

[0106] Step 540, determining the target position of the laser generator according to the intersection point of the compensated optical path before incidence and the plane at a predetermined height.

[0107] In some embodiments, since the laser generator usually moves in a horizontal plane, and the optical path before incidence is the optical path corresponding to the actual detonation point position, therefore, taking the intersection point of the optical path before incidence and the plane where the laser generator is located as the target position of the laser generator.

[0108] As an alternative embodiment, the first region and the second region are concentric annular regions, and the diameter of the second region is smaller than the diameter of the first region.

[0109] In some embodiments, debonding is performed circle by circle from the outside to the inside. Thus, the currently debonded region can be restricted by the bonding adhesive only on one side, and this form of debonding is more conducive to obtaining a better debonding effect.

[0110] As an alternative embodiment, the laser beam emitted by the laser generator is a focused laser beam.

[0111] In some embodiments, the laser generator uses a focused laser beam, that is, the envelope shape of the laser beam is a conical envelope shape, which can focus higher energy in a smaller area, facilitating the rapid debonding of a single burst point.

[0112] As an alternative embodiment, as Figure 8 shown, in step 500, determining the target position of the laser generator according to the part of the optical path to be compensated after entering the substrate and the target burst point position after the second region is deformed includes:

[0113] Step 550, determining two opposite generatrices according to the conical space passed by the part of the optical path to be compensated after entering the substrate;

[0114] In some embodiments, the generatrices on the conical surface intersect at the vertex of the cone. During the debonding process, the vertex position should be located at the burst point position to be debonded.

[0115] Step 560, taking the directions corresponding to the two generatrices as the directions, and using the target burst point position after the second region is deformed as the intersection point, to confirm the two generatrices of the incident part of the compensated optical path;

[0116] In some embodiments, the intersection point of the two generatrices is moved to the target burst point position after deformation, so as to obtain the conical space covered by the laser beam after incidence.

[0117] Step 570, determining the two generatrices of the part of the compensated optical path before incidence according to the two generatrices of the incident part of the compensated optical path;

[0118] In some embodiments, according to the characteristic of the reversibility of the optical path, the two generatrices of the incident part are emitted reversely outside the substrate to obtain the optical path before incidence. The position of the laser generator must be within the path range of the optical path before incidence. Therefore, determining the optical path before incidence can quickly determine the target position of the laser generator.

[0119] Step 580, determining the target position of the laser generator according to the two generatrices of the part before incidence.

[0120] In some embodiments, the target position of the laser generator can be determined according to the intersection points of the two generatrices and the moving plane of the laser generator.

[0121] As an alternative embodiment, the two generatrices are the two generatrices with the largest included angle in the conical space.

[0122] In some embodiments, since the two generatrices with the largest included angle are the outermost edge ranges of the conical laser beam, and the intersections with the conical bottom surface are located at both ends of the diameter of the conical bottom surface, it is more conducive to determining the target position of the laser generator.

[0123] Those of ordinary skill in the art can understand that all or part of the processes in the above method embodiments can be completed by instructing relevant hardware through a computer program. The program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the above method embodiments. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM), etc.

[0124] As mentioned above, the above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for determining the position of a laser generator for debonding, characterized in that Applied to the debonding process of a stacked structure, where the stacked structure is formed by bonding a wafer and a substrate, the method includes: Laser irradiating a first region of the stacked structure and applying a force to separate the wafer and the substrate in the first region; After the separation of the first region, obtaining the position of the second region after deformation; Determining the original optical path based on the original target burst point position corresponding to the second region, the original position of the second region, and the original target position of the laser generator; Determining the optical path to be compensated and the burst point position to be compensated based on the part of the original optical path before entering the substrate and the position of the second region after deformation; wherein, the burst point position to be compensated is determined by refraction of the original optical path through the deformed second region; Moving the original target burst point position along the deformation direction of the second region to obtain the target burst point position of the second region after deformation; Determining the target position of the laser generator based on the part of the optical path to be compensated after entering the substrate and the target burst point position of the second region after deformation; Wherein, determining the target position of the laser generator based on the part of the optical path to be compensated after entering the substrate and the target burst point position of the second region after deformation includes: Moving the part of the optical path to be compensated after entering the substrate so that the burst point position to be compensated moves to the target burst point position, determining the actual laser optical path, and determining the target position of the laser generator based on the actual laser optical path.

2. The method for determining the position of the laser generator for debonding according to claim 1, wherein Laser irradiating a first region of the stacked structure and applying a force to separate the wafer and the substrate in the first region includes: Adsorbing a transparent suction cup on the substrate; Passing laser through the transparent suction cup to irradiate the first region; Applying a force to the substrate in the first region through the transparent suction cup to separate the wafer and the substrate.

3. The method for determining the position of the laser generator for debonding according to claim 2, wherein Passing laser through the transparent suction cup to irradiate the first region includes: Determining the available wavelength range based on the transmission wavelength of the transparent suction cup and the transmission wavelength of the substrate; Passing laser with a wavelength within the available wavelength range through the transparent suction cup to irradiate the first region.

4. The method for determining the position of the laser generator for debonding according to claim 2, characterized in that, The transparent suction cup has a plurality of force-applying pull rods; Applying a force to the substrate in the first region through the transparent suction cup includes: Applying a force to the substrate using at least one force-applying pull rod closest to the first region to separate the wafer and the substrate.

5. The method for determining the position of the laser generator for debonding according to claim 2, wherein Applying a force to the substrate in the first region through the transparent suction cup to separate the wafer and the substrate includes: Increasing the adsorption force of the transparent suction cup on the first region from a first predetermined value to a second predetermined value; Applying a force to the transparent suction cup with a force less than the second predetermined value to separate the wafer and the substrate.

6. The method for determining the position of the laser generator for debonding according to claim 1, wherein Determining the target position of the laser generator based on the part of the optical path to be compensated after entering the substrate and the target burst point position of the second region after deformation includes: Taking the direction of the part of the optical path to be compensated after entering the substrate as the target direction; Taking the propagation path along the target direction and passing through the target burst point position of the second region after deformation as the compensated post-incidence optical path; Determining the compensated pre-incidence optical path based on the compensated post-incidence optical path and the refractive index of the substrate; Determine the target position of the laser generator according to the intersection point of the compensated pre-incidence optical path and the plane at a predetermined height.

7. The method for determining the position of the laser generator for debonding according to claim 1, wherein The first region and the second region are concentric annular regions, and the diameter of the second region is smaller than the diameter of the first region.

8. The method for determining the position of the laser generator for debonding according to claim 1, wherein The laser beam emitted by the laser generator is a focused laser beam.

9. The method for determining the position of the laser generator for debonding according to claim 8, wherein Determining the target position of the laser generator according to the part of the optical path to be compensated after entering the substrate and the target detonation point position after the second region is deformed includes: Determine two opposite generatrices according to the conical space passed by the part of the optical path to be compensated after entering the substrate; Taking the directions corresponding to the two generatrices as the directions, and using the target detonation point position after the second region is deformed as the intersection point, confirm the two generatrices of the incident part of the compensated optical path; Confirm the two generatrices of the pre-incidence part of the compensated optical path according to the two generatrices of the incident part of the compensated optical path; Determine the target position of the laser generator according to the two generatrices of the pre-incidence part.

10. The method for determining the position of the laser generator for debonding according to claim 9, wherein The two generatrices are the two generatrices with the largest included angle in the conical space.

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