Laser Debonding Method

Abstract

The present invention provides a laser debonding method, which is applied to the debonding process of a stacked structure having a wafer and a substrate, and the method comprises: using a laser generator to irradiate the current target area of ​​the stacked structure so that the bonding material in the stacked structure undergoes a phase change; applying a pulling force to the current target area so that the target area of ​​the stacked structure is separated; determining the position of the next target area and moving the laser generator so that the laser generator can irradiate the position of the next target area. The present invention can separate the stacked structure after irradiating a part of the stacked structure, reduce heat loss, and improve the debonding effect.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor processing, and in particular to a laser debonding method. Background Art

[0002] In the field of semiconductor manufacturing, it is often necessary to thin the thickness of a semiconductor wafer. Therefore, the back of the thick semiconductor wafer must be thinned (grinded and cut) after loading the integrated circuit. During the processing, a substrate is usually used to temporarily bond the semiconductor wafer. The substrate serves as the base of the semiconductor wafer during the processing to protect the semiconductor wafer from being damaged due to the thinning of the thickness. After the semiconductor wafer is thinned, the semiconductor wafer and the substrate must be debonded.

[0003] In the prior art, in the process of debonding the semiconductor wafer and the substrate, the debonding of the semiconductor wafer and the substrate is achieved by dissolving the bonding adhesive with a chemical solvent, by thermal sliding peeling, or by laser debonding. For laser debonding, it is usually necessary to irradiate all the bonding adhesive with a laser to cause a phase change, and then apply force to separate the semiconductor wafer and the substrate.

[0004] In the process of realizing the present invention, the inventors found that there are at least the following technical problems in the prior art: since the laser irradiation process of the bonding glue needs to be performed point by point, and there is a long time difference between the last irradiated bonding glue and the first irradiated bonding glue, therefore, during the force separation process, the bonding glue in different areas is in different states, which is not conducive to the separation of the semiconductor wafer and the substrate. Summary of the invention

[0005] The laser debonding method provided by the present invention can separate the laminated structure after irradiating a part of the laminated structure, thereby reducing heat loss and improving the debonding effect.

[0006] The present invention provides a laser debonding method, which is applied to a debonding process of a stacked structure having a wafer and a substrate, and the method comprises:

[0007] Using a laser generator to irradiate a current target area of ​​the stacked structure so as to cause a phase change of a bonding material in the stacked structure;

[0008] Applying a pulling force to the current target area to separate the target area of ​​the stacked structure;

[0009] The position of the next target area is determined and the laser generator is moved so that the laser generator can irradiate the next target area.

[0010] Optionally, determining the position of the next target area includes:

[0011] Stepping along the circumference of the stacked structure by a first predetermined distance to determine a next position area;

[0012] The position of the next target area is determined according to the separation state of the next position area.

[0013] Optionally, determining the position of the next target area according to the separation state of the next position area includes:

[0014] When the separation state of the next location area is an unseparated state, determining the next location area as the next target area;

[0015] When the separation state of the next position area is the separated state, the step is made along the radial direction of the stacked structure by a second predetermined distance to determine the next target area.

[0016] Optionally, determining the position of the next target area includes: stepping along the radial direction of the wafer by a third predetermined distance to determine the position of the next target area.

[0017] Optionally, irradiating the current target area of ​​the laminate structure with a laser generator includes:

[0018] irradiating a current target point in the target area;

[0019] Stepping along the circumference of the wafer by a fourth predetermined distance to determine the position of a next point in the current target area;

[0020] When the next point position is the irradiated position, stop irradiating the current target area;

[0021] When the next point position is a non-irradiated position, the next point position is used as the next target point.

[0022] Optionally, before irradiating the current target area of ​​the stacked structure with a laser generator, the method further includes:

[0023] The transparent suction cup and the substrate of the laminated structure are adsorbed at a first adsorption pressure, so that the laser can irradiate the target area through the transparent suction cup, and the transparent suction cup can apply a pulling force to the target area.

[0024] Optionally, after adsorbing the transparent suction cup and the substrate of the laminated structure at a first adsorption pressure, the method further comprises:

[0025] Acquire a first transmission wavelength capable of transmitting the transparent suction cup;

[0026] Acquire a second transmission wavelength capable of transmitting the substrate;

[0027] The wavelength of the laser is determined according to the first transmission wavelength and the second transmission wavelength.

[0028] Optionally, before applying the pulling force to the current target area, the method further includes:

[0029] The adsorption pressure between the transparent suction cup and the current target area is increased to a second adsorption pressure.

[0030] Optionally, the transparent suction cup has a plurality of force application areas;

[0031] Applying a pulling force to the current target area includes:

[0032] Determining a first force application area to be applied with tension according to the positions of the target area and the force application area;

[0033] Apply a tensile force to the first force application area.

[0034] Optionally, the transparent suction cup has a plurality of force application area sets, each of which has a plurality of force application areas; wherein,

[0035] The multiple force application areas in each force application area set are arranged in a ring shape to form a force application area set array;

[0036] Each force application area set array is arranged concentrically with the transparent suction cup.

[0037] In the technical solution provided by the present invention, a part of the laminated structure is irradiated, and then the irradiated area is separated by force. After the separation of the area is completed, the next area is processed. Therefore, the irradiated area can be separated in time, so that the irradiation step and the force separation step of the local laminated structure are carried out continuously. Therefore, in the technical solution provided by the present invention, for the local laminated structure, after irradiation, there will be no heat loss and the bonding glue will not re-solidify, which can ensure the separation effect of the substrate and the semiconductor wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a flow chart of a laser debonding method according to an embodiment of the present invention;

[0039] Figure 2 A flow chart of determining a next target area in a laser debonding method according to another embodiment of the present invention;

[0040] Figure 3 A flow chart of determining a next target area in a laser debonding method according to another embodiment of the present invention;

[0041] Figure 4This is a flow chart of irradiating the current target area by a laser debonding method according to another embodiment of the present invention;

[0042] Figure 5 A flow chart of determining the laser wavelength in a laser debonding method according to another embodiment of the present invention;

[0043] Figure 6 This is a flow chart of applying force to a current target area by a laser debonding method according to another embodiment of the present invention. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] The embodiment of the present invention provides a laser debonding method, such as Figure 1 As shown, the method is applied to a debonding process of a stacked structure having a wafer and a substrate, and includes:

[0046] Step 100, using a laser generator to irradiate a current target area of ​​the stacked structure, so as to cause a phase change of a bonding material in the stacked structure;

[0047] In some embodiments, the current target region refers to a continuous region on the stacked structure, and the continuous region is subjected to at least one laser irradiation. After the current target region is irradiated, the bonding material in the current region undergoes a phase change.

[0048] Step 200, applying a pulling force to the current target area to separate the target area of ​​the stacked structure;

[0049] In some embodiments, since the bonding material in the current region undergoes a phase change, the substrate and the wafer can be separated in the current region. To separate the substrate and the wafer, force is applied to the substrate and the wafer so that the substrate and the wafer undergo a slight deformation and are separated.

[0050] Step 300, determine the position of the next target area and move the laser generator so that the laser generator can irradiate the next target area.

[0051] In some embodiments, for the current target area, the force separation is performed in time after the laser irradiation, which can ensure that the current target area can be well separated. After the current target area is separated, the position of the next target area can be determined. When the position of the next target area is determined and the laser generator is moved to the corresponding position, the process returns to step 100. The next target area is usually an area adjacent to the current target area.

[0052] In the technical solution provided in this embodiment, a part of the laminated structure is irradiated, and then the irradiated area is separated by force. After the separation of the area is completed, the next area is processed. Therefore, the irradiated area can be separated in time, so that the irradiation step and the force separation step of the local laminated structure are carried out continuously. Therefore, in the technical solution provided in this embodiment, for the local laminated structure, after irradiation, there will be no heat loss and the bonding glue will not re-solidify, which can ensure the separation effect of the substrate and the semiconductor wafer.

[0053] As an optional implementation, Figure 2 As shown, determining the position of the next target area in step 300 includes:

[0054] Step 310, stepping along the circumference of the stacked structure by a first predetermined distance to determine a next position area;

[0055] In some embodiments, the stepping is performed along the circumference of the laminate structure, that is, during the entire debonding process, the debonding process is performed inwardly in circles. The first predetermined distance is a predetermined stepping distance, for example, the first predetermined distance is determined according to the size of the heat affected zone of a single laser irradiation, and specifically, for example, an integer multiple of the circumferential size of the heat affected zone of a single laser irradiation can be used as the first predetermined distance.

[0056] Step 320, determining the position of the next target area according to the separation state of the next location area.

[0057] In some embodiments, the separation state of the next position area refers to whether the current state of the next position area is a classified state or an unseparated state. This state indicates whether a circle of areas under the current radius has been separated. When a circle of areas under the current radius has been separated, a circle of areas with a smaller radius can be irradiated and separated.

[0058] In this embodiment, by determining the separation state of the next position area, the stepping direction of the next target area can be determined, and the position of the next target area can be determined more accurately.

[0059] As an optional implementation, Figure 3As shown, in step 320, determining the position of the next target area according to the separation state of the next location area includes:

[0060] Step 321, when the separation state of the next location area is the unseparated state, determining the next location area as the next target area;

[0061] In some embodiments, when the separation state of the next position area is an unseparated state, it indicates that a circle of areas under the current radius has not been completely separated. Therefore, the next position area is determined as the next target area to continue irradiating and separating a circle of areas under the current radius.

[0062] Step 322: when the separation state of the next position area is the separated state, stepping along the radial direction of the stacked structure by a second predetermined distance to determine the next target area.

[0063] In some embodiments, when the separation state of the next position area is the separated state, it indicates that the one circle area under the current radius has been completely separated. At this time, it is necessary to continue to separate the one circle area with a radius smaller than the current radius. Therefore, the second predetermined distance is stepped along the radial direction of the stacked structure to determine the radius of the next circle area. The second predetermined distance is usually determined based on the radial size of the heat-affected area of ​​a single irradiation. For example, the second predetermined distance is determined by an integer multiple of the radial size of the heat-affected area of ​​the stacked structure along the single irradiation.

[0064] As an optional implementation, determining the position of the next target area in step 300 includes: step 330, stepping along the radial direction of the wafer by a third predetermined distance to determine the position of the next target area.

[0065] In some embodiments, the laminate structure can be divided into a plurality of concentric annular regions in the radial direction, and the annular region currently being irradiated and separated is the current target region. At this time, after the current target region is irradiated and separated, when the next target region is determined, stepping is performed in the radial direction. The third predetermined distance is usually determined based on the radial size of the heat-affected region of a single irradiation. For example, the third predetermined distance is determined by an integer multiple of the radial size of the heat-affected region of a single irradiation in the laminate structure.

[0066] As an optional implementation, Figure 4 As shown, in step 100, irradiating the current target area of ​​the stacked structure with a laser generator includes:

[0067] Step 110, irradiating the current target point in the target area;

[0068] In some embodiments, when the annular region is the current target region, it is obviously necessary to irradiate the current region multiple times to complete the separation of the current target region.

[0069] Step 120, stepping along the circumference of the wafer at a fourth predetermined distance to determine the position of the next point in the current target area;

[0070] In some embodiments, in order to achieve separation in the current target area, the current target area is irradiated point by point, and after the irradiation is completed in the current target area, the current target area is separated. The fourth predetermined distance is a predetermined step distance, for example, the fourth predetermined distance is determined according to the size of the heat-affected area of ​​a single laser irradiation, and specifically, for example, an integer multiple of the circumferential size of the heat-affected area of ​​a single laser irradiation can be used as the fourth predetermined distance.

[0071] Step 121, when the next point position is the irradiated position, stop irradiating the current target area;

[0072] In some embodiments, when the next position has been irradiated, it indicates that the entire annular area of ​​the current target area has been irradiated, and therefore, the irradiation of the current target area is stopped and force separation of the current target area is started.

[0073] Step 122, when the next point position is a non-irradiated position, the next point position is used as the next target point.

[0074] In some embodiments, when the next position is not irradiated, it indicates that the entire annular area of ​​the current target area has not yet been irradiated, and therefore, the next target point is continuously irradiated to complete the irradiation of the entire annular area.

[0075] In this embodiment, the stacked structure is divided into multiple concentric annular areas, and each area is irradiated multiple times before force separation. Compared with the situation where force separation is performed once after each irradiation, the number of force separations is reduced in this embodiment, the efficiency is improved, and at the same time, it can also ensure good separation of the current target area.

[0076] As an optional implementation, step 100, before irradiating the current target area of ​​the stacked structure with a laser generator, further includes:

[0077] Step 010, adsorbing the transparent suction cup and the substrate of the laminated structure at a first adsorption pressure, so that the laser can penetrate the transparent suction cup to irradiate the target area, and the transparent suction cup can apply a pulling force to the target area.

[0078] In some embodiments, in order to ensure that the separation can be performed after the irradiation of a single area is completed, a transparent suction cup is adsorbed together with the substrate of the laminated structure, so that the laser can pass through the suction cup to irradiate the target area. After the irradiation is completed, the transparent suction cup can be used to separate the layers by applying force. It can be seen that the transparent suction cup is transparent to the laser, so it does not affect the irradiation of the laser after being pre-adsorbed on the substrate. At the same time, it can also be separated by applying force as soon as possible after the irradiation is completed. The first adsorption pressure is a pre-set adsorption pressure, which can usually be determined based on the pressure required when the laminated structure is fixedly adsorbed.

[0079] As an optional implementation, Figure 5 As shown, in step 010, after the transparent suction cup and the substrate of the laminated structure are adsorbed at a first adsorption pressure, the method further includes:

[0080] Step 020, obtaining a first transmission wavelength capable of transmitting the transparent suction cup;

[0081] In some embodiments, for a transparent suction cup, its intrinsic absorption limit can be calculated according to the following formula:

[0082]

[0083] Among them, E g is the bandgap width of the transparent suction cup material, λ c is the intrinsic absorption limit of the transparent suction cup.

[0084] According to the intrinsic absorption edge of the transparent suction cup, the first transmission wavelength that the transparent suction cup can transmit can be determined.

[0085] Step 030, obtaining a second transmission wavelength capable of transmitting the substrate;

[0086] In some embodiments, the calculation method in step 020 can also be used to calculate the second transmission wavelength that the substrate can transmit.

[0087] Step 040: Determine the wavelength of the laser according to the first transmission wavelength and the second transmission wavelength.

[0088] In some embodiments, in order to ensure the irradiation effect of the laser on the bonding material, the intersection of the first projection wavelength and the second transmission wavelength is used as an optional wavelength range, so that the laser can pass through the transparent suction cup and the substrate to achieve the irradiation effect on the bonding material.

[0089] As an optional implementation, before applying the tension to the current target area in step 200, the following steps may also be included:

[0090] Step 210: increasing the adsorption pressure between the transparent suction cup and the current target area to a second adsorption pressure.

[0091] In some embodiments, when applying a pulling force to the current target area, it is necessary to ensure that the pulling force can be transmitted to the substrate through the transparent suction cup during the application process. Therefore, the adsorption pressure of the transparent suction cup on the substrate is increased. The second adsorption pressure can be, for example, the adsorption pressure when the gas valve of the suction cup is fully opened. Similarly, the aforementioned first adsorption pressure can be the adsorption pressure when the gas valve of the suction cup is opened by 30% or 40%.

[0092] As an optional implementation, Figure 6 As shown, the transparent suction cup has multiple force application areas;

[0093] Applying tension to the current target area in step 200 includes:

[0094] Step 220, determining a first force application area to be applied with tension according to the positions of the target area and the force application area;

[0095] In some embodiments, since it is necessary to apply force to separate the area that has been irradiated with laser during the force separation process, the positions of the current target area and multiple force application areas are compared in this step to determine which force application area should be used to apply force to the current target area, for example, the force application area that is closest to the current target area is used as the first force application area.

[0096] Step 230: Apply tension to the first force application area.

[0097] In some embodiments, after the first force application area is determined, the force separation on the current target area can be achieved by applying a pulling force to the first force application area.

[0098] As an optional implementation, the transparent suction cup has a plurality of force application area sets, each of which has a plurality of force application areas; wherein,

[0099] The multiple force application areas in each force application area set are arranged in a ring shape to form a force application area set array;

[0100] Each force application area set array is arranged concentrically with the transparent suction cup.

[0101] In some embodiments, when the multiple regions of the stacked structure are concentric annular regions, after a single annular region is irradiated, a corresponding set of force application regions may be used to apply force simultaneously, thereby separating the force application to the current target region.

[0102] Those skilled in the art can understand that all or part of the processes in the above method embodiments can be implemented by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium, and when the program is executed, it can include the processes in the above method embodiments. The storage medium can be a disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM), etc.

[0103] The above is only a specific embodiment 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 a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A laser debonding method, characterized in that: Applied in a debonding process of a stacked structure having a wafer and a substrate, the method comprises: Adsorbing the transparent suction cup and the substrate of the laminated structure at a first adsorption pressure, so that the laser can penetrate the transparent suction cup to irradiate the target area, and the transparent suction cup can apply a pulling force to the target area; wherein the transparent suction cup has a plurality of force application area sets, each force application area set has a plurality of force application areas; wherein the plurality of force application areas in each force application area set are arranged in a ring shape to form a force application area set array; each force application area set array is concentrically arranged with the transparent suction cup; Using a laser generator to irradiate a current target area of ​​the stacked structure so as to cause a phase change of a bonding material in the stacked structure; Applying a pulling force to the current target area to separate the target area of ​​the stacked structure; The position of the next target area is determined and the laser generator is moved so that the laser generator can irradiate the next target area.

2. The laser debonding method according to claim 1, characterized in that: Determining the location of the next target area includes: Stepping along the circumference of the stacked structure by a first predetermined distance to determine a next position area; The position of the next target area is determined according to the separation state of the next position area.

3. The laser debonding method according to claim 2, characterized in that: Determining the position of the next target area according to the separation state of the next position area includes: When the separation state of the next location area is an unseparated state, determining the next location area as the next target area; When the separation state of the next position area is the separated state, the step is made along the radial direction of the stacked structure by a second predetermined distance to determine the next target area.

4. The laser debonding method according to claim 1, characterized in that: Determining the position of the next target area includes: stepping along the radial direction of the wafer by a third predetermined distance to determine the position of the next target area.

5. The laser debonding method according to claim 4, characterized in that: The laser generator is used to irradiate the current target area of ​​the stacked structure including: irradiating a current target point in the target area; Stepping along the circumference of the wafer by a fourth predetermined distance to determine the position of a next point in the current target area; When the next point position is the irradiated position, stop irradiating the current target area; When the next point position is a non-irradiated position, the next point position is used as the next target point.

6. The laser debonding method according to claim 1, characterized in that: After the transparent suction cup and the substrate of the laminated structure are adsorbed at a first adsorption pressure, the following step further comprises: Acquire a first transmission wavelength capable of transmitting the transparent suction cup; Acquire a second transmission wavelength capable of transmitting the substrate; The wavelength of the laser is determined according to the first transmission wavelength and the second transmission wavelength.

7. The laser debonding method according to claim 1, characterized in that: Before applying tension to the current target area, it also includes: The adsorption pressure between the transparent suction cup and the current target area is increased to a second adsorption pressure.

8. The laser debonding method according to claim 1, characterized in that: The transparent suction cup has a plurality of force application areas; Applying a pulling force to the current target area includes: Determining a first force application area to be applied with tension according to the positions of the target area and the force application area; Apply a tensile force to the first force application area.

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