Wafer de-bonding method

Abstract

The invention discloses a wafer de-bonding method. The wafer de-bonding method comprises the steps that S1, a wafer and a carrier which are fixed together are installed on a machining table; and S2, moving a laser light source into a first plane in the height direction of the bonding layer, and adjusting the laser light source to enable a laser beam emitted by the laser light source to irradiate the bonding layer in the direction perpendicular to the thickness direction of the bonding layer. And S3, controlling the laser light source to rotate in a first plane by taking the bonding layer as a center and / or controlling the processing table to rotate so as to utilize the laser light source to emit the laser beam to at least partially decompose or at least partially ablate the bonding layer. According to the wafer de-bonding method, the problem of single carrier selection in the prior art is solved.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and more particularly, to a method for wafer debonding. Background Art

[0002] (Laser) debonding of a wafer refers to focusing a laser on a bonding layer between the wafer and a carrier. After the bonding layer interacts with the laser, the bonding layer loses its adhesiveness, thereby separating the wafer from the carrier.

[0003] However, existing wafer debonding methods typically require the laser to pass through the carrier and then interact with the bonding layer, which means that the carrier must be made of a transparent material, resulting in a limited choice of carriers. Summary of the Invention

[0004] The main objective of this application is to provide a method for wafer debonding to at least solve the problem of limited carrier selection in the prior art.

[0005] According to one aspect of this application, a method for wafer debonding is provided. The method for wafer debonding is used to debond a wafer fixed on a carrier. The wafer is fixed to the carrier through a bonding layer. The method for wafer debonding includes:

[0006] Step S1: Mount the wafer and the carrier fixed together on a processing table;

[0007] Step S2: Move the laser light source to a first plane in the height direction where the bonding layer is located, and adjust the laser light source so that the laser beam emitted by the laser light source irradiates the bonding layer in a direction perpendicular to the thickness direction of the bonding layer;

[0008] Step S3: Control the laser light source to rotate in the first plane with the bonding layer as the center and / or control the processing table to rotate self - clockwise, so as to use the laser beam emitted by the laser light source to at least partially decompose or at least partially ablate the bonding layer.

[0009] Further, the step of controlling the laser light source to rotate in the first plane with the bonding layer as the center and / or controlling the processing table to rotate self - clockwise includes:

[0010] Control the laser light source to rotate in the first plane with the bonding layer as the center at a first rotational angular velocity ω1, where the value of the first rotational angular velocity ω1 satisfies the relationship: 10 -7 / (R1*t) ≤ ω1 ≤ 10 -4 / (R1*t), where R1 represents the radius of the wafer or half of the maximum length of the wafer, and t represents the time that the laser stays at each point on the bonding layer; or,

[0011] Control the processing table to rotate self - clockwise at a second rotational angular velocity ω2, where the value of the second rotational angular velocity ω2 satisfies the relation: 10 -7 / (R1*t) ≤ ω2 ≤ 10 -4 / (R1*t), where R1 represents the radius of the wafer or half of the maximum length of the wafer, and t represents the time that the laser stays at each position on the bonding layer.

[0012] Further, the steps of controlling the laser light source to rotate in the first plane centered on the bonding layer and / or controlling the processing table to rotate self - clockwise include:

[0013] Control the laser light source to rotate in the first plane centered on the bonding layer along a first rotation direction, and control the processing table to rotate self - clockwise along a second rotation direction opposite to the first rotation direction or rotate self - clockwise along the first rotation direction, where the angular velocity ω1 of the laser light source is different from the angular velocity ω2 of the wafer and the carrier;

[0014] Wherein, when both the laser light source and the processing table rotate along the first rotation direction, the value of the angular velocity ω1 of the laser light source and the value of the angular velocity ω2 of the processing table satisfy the relation: 10 -7 / (R1*t) ≤ ω1 - ω2 ≤ 10 -4 / (R1*t); when the laser light source and the processing table rotate in opposite directions, the value of the angular velocity ω1 of the laser light source and the value of the angular velocity ω2 of the processing table satisfy the relation: 10 -7 / (R1*t) ≤ ω1 + ω2 ≤ 10 -4 / (R1*t), where R1 represents the radius of the wafer or half of the maximum length of the wafer, and t represents the time that the laser stays at each position on the bonding layer.

[0015] Further, the wafer debonding method further includes:

[0016] Use a laser spot regulator to adjust the laser beam so that the diameter of the spot of the laser beam is less than or equal to the thickness of the bonding layer; and / or,

[0017] Control the laser light source to move along the height direction of the bonding layer so that in the thickness direction of the bonding layer, the spot of the laser beam irradiated on the bonding layer is located between the surface where the bonding layer contacts the wafer and the surface of the carrier on the side away from the wafer.

[0018] Further, the steps after moving the laser light source to the first plane in the height direction where the bonding layer between the wafer and the carrier is located include:

[0019] Control the movement of the laser light source in a direction close to or away from the bonding layer so that the distance between the laser light source and the geometric center of the bonding layer is less than or equal to a first predetermined distance.

[0020] Furthermore, the focal length of the laser beam is located within the bonding layer. If the diameter or maximum length of the wafer is greater than twice the depth of focus A of the laser beam, the steps after step S3 include:

[0021] Separate the remaining bonding layer between the wafer and the carrier by at least one of direct cutting, gas cutting, solvent jet separation, ultrasonic vibration separation, thermal separation, and tensile separation.

[0022] Furthermore, the carrier includes a light-transmitting carrier and a non-light-transmitting carrier;

[0023] Among them, the light-transmitting carrier includes at least one of a glass carrier, a diamond carrier, a quartz carrier, a silicon carbide carrier, and a sapphire carrier;

[0024] The non-light-transmitting carrier includes at least one of a titanium carbide carrier, a silicon carrier, a ceramic carrier, a gallium arsenide carrier, an indium phosphide carrier, a gallium nitride carrier, a copper carrier, and a steel carrier.

[0025] Furthermore, the steps after controlling the laser light source to emit the laser beam further include:

[0026] Control gas to purge the contact point between the laser beam and the bonding layer to remove the gas or impurities generated when the bonding layer decomposes or ablates.

[0027] Furthermore, the steps of fixing the wafer and the carrier include:

[0028] Fix at least one of the wafer and the carrier, and apply a tensile force to at least one of the wafer and the carrier in the thickness direction of the bonding layer, and the tensile forces applied to the wafer and the carrier are in opposite directions.

[0029] Furthermore, the laser light source includes at least one of an ultraviolet laser light source and an infrared laser light source;

[0030] Among them, the wavelength λ1 of the laser beam of the ultraviolet laser light source satisfies the relationship: 10 nm ≤ λ1 ≤ 400 nm; and / or,

[0031] The wavelength λ2 of the laser beam of the infrared laser light source satisfies the relationship: 1 μm ≤ λ2 ≤ 11 μm.

[0032] Compared with the prior art, in the present application, after the wafer and the carrier are mounted on the processing table, the laser light source is moved to the first plane, and then the laser light source is adjusted so that the laser beam of the laser light source can directly act on the bonding layer in a direction parallel to the first plane. Subsequently, when the laser light source rotates around the bonding layer in the first plane or the processing table rotates, the laser light source is started to emit a laser beam at this time, so that the laser beam uniformly acts on the bonding layer, thereby achieving the purpose of debonding. Compared with the prior art, the laser beam in the present application directly acts on the bonding layer without passing through the carrier before acting on the bonding layer. That is to say, the carrier in the present application does not need to be light-transmissive, so the selectivity of the carrier is also wider than that of the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings described herein are used to provide a further understanding of the present application and form a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation to the present application. In the drawings:

[0034] Figure 1 is a logical schematic diagram of the wafer debonding method disclosed in the present application;

[0035] Figure 2 is a schematic flow chart of the principle of a wafer debonding method disclosed in the present application;

[0036] Figure 3 is a schematic flow chart of the principle of another wafer debonding method disclosed in the present application;

[0037] Figure 4 is a schematic structural diagram of the wafer debonding adopted in the present application;

[0038] Figure 5 is a top view of the structure of the wafer debonding adopted in the present application;

[0039] Figure 6 is an enlarged schematic diagram of the laser beam disclosed in the present application.

[0040] Among them, the above-mentioned drawings include the following reference numerals:

[0041] 10. Wafer; 20. Carrier; 30. Bonding layer; 40. Laser light source; 41. Laser beam; 50. Laser spot adjuster; 60. Processing table; 61. First suction cup; 62. Second suction cup; 70. Position controller. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0043] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0044] Unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that for the convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technologies, methods, and devices should be regarded as part of the authorized specification. In all the examples shown and discussed here, any specific value should be interpreted as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0045] See Figures 1 to 6 As shown, according to an embodiment of the present application, a wafer debonding method is provided. The wafer debonding method is used to debond a wafer 10 fixed to a carrier 20. The wafer 10 is fixed to the carrier 20 through a bonding layer 30. The wafer debonding method includes: Step S1: Mount the wafer 10 and the carrier 20 fixed together on a processing table 60.

[0046] Actually, during the process of mounting the wafer 10 and the carrier 20 on the processing table 60, it is necessary to keep the wafer 10 and the carrier 20 stacked in the height direction of the processing table 60 to facilitate subsequent debonding of the bonding layer 30. At the same time, when fixing the wafer 10 and the carrier 20, the wafer 10 can be fixed on the processing table 60, or the carrier 20 can be fixed on the processing table 60. The processing table 60 can be a pneumatic floating platform or a piezoelectric flexible platform, and the above platforms can provide high movement accuracy to facilitate precise processing of the wafer 10.

[0047] Step S2: Move the laser light source 40 to a first plane in the height direction (such as the Z direction in the attached Figure 4 figure) where the bonding layer 30 is located, and adjust the laser light source 40 so that the laser beam 41 emitted by the laser light source 40 irradiates the bonding layer 30 in a direction perpendicular to the thickness direction of the bonding layer 30.

[0048] In step S2, moving the laser light source 40 to the first plane is to ensure that after the laser is started, the laser can directly act on the bonding layer 30 without passing through the carrier 20 or the wafer 10 before acting on the bonding layer 30. Additionally, adjust the laser beam 41 emitted by the laser light source 40 to irradiate the bonding layer 30 along the direction perpendicular to the thickness direction of the bonding layer 30, that is, adjust the emission angle of the laser light source 40 to avoid a large deviation angle of the laser beam 41 emitted by the laser light source 40, resulting in the laser beam 41 being unable to act on the bonding layer 30. The device for controlling the movement of the laser light source 40 can use a position controller 70. That is, the position controller 70 can drive the laser light source 40 to move in the entire three-dimensional space and move the laser light source 40 to a specific location according to the X, Y, and Z coordinates. The process of adjusting the laser light source 40 can be coordinated by a manipulator and an optical scanner. The position controller 70 can be selected as a six-axis six-degree-of-freedom positioner to improve the movement accuracy of the laser light source 40.

[0049] Step S3: Control the laser light source 40 to rotate in the first plane with the bonding layer 30 as the center and / or control the processing table 60 to rotate itself, so as to use the laser beam 41 emitted by the laser light source 40 to at least partially decompose or at least partially ablate the bonding layer 30.

[0050] In step S3, the purpose of controlling the rotation of the laser light source 40 or the processing table 60 is to make the laser beam 41 act on the bonding layer 30 evenly, thereby avoiding the situation where when the processing table 60 and the laser light source 40 are both fixed, since the laser cannot act on the bonding layer 30 evenly, resulting in a large part of the bonding layer 30 not being ablated or decomposed by the laser, and the wafer 10 and the carrier 20 remaining fixed together, leading to the failure of the laser debonding process.

[0051] It can be understood that in this embodiment, after the wafer 10 and the carrier 20 are installed on the processing table 60, the laser light source 40 is moved to the first plane, and then the laser light source 40 is adjusted so that the laser beam 41 of the laser light source 40 can directly act on the bonding layer 30 in a direction parallel to the first plane. Subsequently, when the laser light source 40 rotates in the first plane with the bonding layer 30 as the center or the processing table 60 rotates itself, at this time, the laser light source 40 is started to emit the laser beam 41, so that the laser beam 41 acts on the bonding layer 30 evenly, thereby achieving the purpose of debonding. Compared with the prior art, the laser beam 41 of the present application directly acts on the bonding layer 30 without the laser beam 41 acting on the bonding layer 30 after passing through the carrier 20. That is to say, the carrier 20 of the present application does not need to be light-transmissive, so the selectivity of the carrier 20 is also wider than that of the prior art.

[0052] In some embodiments, the steps of controlling the laser light source 40 to rotate in a first plane centered on the bonding layer 30 and / or controlling the processing table 60 to rotate itself include: controlling the laser light source 40 to rotate in the first plane centered on the bonding layer 30 at a first rotational angular velocity ω1, where the value of the first rotational angular velocity ω1 satisfies the relationship: 10 -7 / (R1*t) ≤ ω1 ≤ 10 -4 / (R1*t), where R1 represents the radius of the wafer 10 or half of the maximum length of the wafer 10, and t represents the time for the laser to stay at each location on the bonding layer 30.

[0053] It can be understood that when the laser light source 40 rotates in the first plane centered on the bonding layer 30 while the processing table 60 remains stationary, the first rotational angular velocity ω1 of the laser light source 40 is the relative angular velocity between the laser light source 40 and the processing table 60. By controlling the magnitude of the first rotational angular velocity ω1, the laser beam 41 can be evenly irradiated on the bonding layer 30. At the same time, according to the formula t = D / v, where D represents the spot diameter of the laser beam 41 and t represents the residence time of the laser at each point on the bonding layer 30, that is, the dwell time of the laser. From the linear velocity formula v = ω1*R1, where v is the linear velocity of the laser beam 41 irradiated on the outer periphery of the bonding layer 30, and combining with the formula t = D / v, we can obtain ω1 = D / (R1*t). In this embodiment, the thickness of the bonding layer 30 is between 0.1 μm and 100 μm. Therefore, when the value range of D in this embodiment can be from 0.1 μm to 100 μm, thus according to the above formula, we can get: 10 -7 / (R1*t) ≤ ω1 ≤ 10 -4 / (R1*t). Depending on the frequency of the laser light source 40 and the material of the bonding layer 30, after the bonding layer 30 interacts with the laser beam 41, the decomposition or ablation time is also different. That is to say, after the bonding layer 30 needs to be in contact with the laser for a certain time, the bonding layer 30 reaches the energy threshold for decomposition or ablation before decomposition or ablation will occur. In fact, the value of the residence time t only affects the relative angular velocity between the laser light source 40 and the bonding layer 30. When the residence time t is consistent with the time when the bonding layer 30 ablates or decomposes after contacting the laser, the corresponding ω1 value is the best at this time, that is, the laser can quickly decompose or ablate the bonding layer 30 at this angular velocity value, and the debonding time can be greatly shortened. When the residence time t is less than the time when the bonding layer 30 ablates or decomposes after contacting the laser, even if the laser acts on each part of the bonding layer 30 for a relatively short time after rotating one circle, but when the laser rotates multiple times and continuously irradiates the bonding layer 30, the energy of each part of the bonding layer 30 will always reach the energy threshold for dissolution or decomposition, and finally decompose or dissolve. In addition, it is worth mentioning that the laser cannot penetrate most of the bonding layer 30, that is to say, only the bonding layer 30 in contact with the laser is easy to decompose. Therefore, after the laser rotates multiple circles, the bonding layer 30 can be completely decomposed or ablated. It is worth mentioning that the unit of ω1 is rad / s and the unit of R1 is m. Optionally, the shape of the wafer 10 can be circular, rectangular, or other irregular shapes. When the wafer 10 is circular, R1 represents the radius of the wafer 10. When the wafer 10 is other shapes, R1 represents half of the maximum length of the wafer 10. The radius or maximum length of the bonding layer 30 is the same as the radius or maximum length of the wafer 10.

[0054] In some embodiments, the steps of controlling the laser light source 40 to rotate in the first plane with the bonding layer 30 as the center and / or controlling the processing table 60 to rotate self include: controlling the processing table 60 to rotate self with a second rotational angular velocity ω2, where the value of the second rotational angular velocity ω2 satisfies the relationship: 10 -7 / (R1*t) ≤ ω2 ≤ 10 -4 / (R1*t).

[0055] Similarly, in this embodiment, the second rotational angular velocity ω2 is actually also the relative angular velocity between the outer periphery of the bonding layer 30 and the laser light source 40. Therefore, when the spot diameter of the laser beam 41 ranges from 0.1 μm to 100 μm, the value of the angular velocity ω2 of the outer periphery of the bonding layer 30 in contact with the laser beam 41 can be: 10 -7 / (R1*t) ≤ ω2 ≤ 10 -4 / (R1*t). When the value of ω2 is greater than 10 -4When it is ω2 > 10 / (R1*t), it will cause the rotation speed of the processing table 60 to be too fast, and the contact time between the laser and various parts of the bonding layer 30 is too short. It takes a relatively long time for the bonding layer 30 to decompose or ablate, increasing the debonding time. Similarly, in this embodiment, the unit of ω2 is rad / s and the unit of R1 is m. When ω2 is less than 10 -7 / (R1*t), the contact time between the laser and each contact point on the bonding layer 30 is too long, reducing the debonding efficiency.

[0056] In some embodiments, the steps of controlling the laser light source 40 to rotate in the first plane with the bonding layer 30 as the center and / or controlling the processing table 60 to rotate on its own axis include: controlling the laser light source 40 to rotate in the first plane with the bonding layer 30 as the center along the first rotation direction (such as the Figure 5 X1 direction in the figure), and controlling the processing table 60 to rotate on its own axis along the second rotation direction opposite to the first rotation direction (such as the Figure 5 X2 direction in the figure) or rotate along the first rotation direction. The angular velocity ω1 of the laser light source 40 is different from the angular velocity ω2 of the wafer 10 and the carrier 20. Among them, when both the laser light source 40 and the processing table 60 rotate along the first rotation direction, the numerical value of the angular velocity ω1 of the laser light source 40 and the numerical value of the angular velocity ω2 of the processing table 60 satisfy the relationship: 10 -7 / (R1*t) ≤ ω1 - ω2 ≤ 10 -4 / (R1*t); when the laser light source 40 and the processing table 60 rotate in opposite directions, the numerical value of the angular velocity ω1 of the laser light source 40 and the numerical value of the angular velocity ω2 of the processing table 60 satisfy the relationship: 10 -7 / (R1*t) ≤ ω1 + ω2 ≤ 10 -4 / (R1*t).

[0057] Actually, whether the laser light source 40 rotates or not, and whether the processing table 60 rotates or not, or both the laser light source 40 and the processing table 60 rotate, and the rotation directions are the same or different, actually to make the residence time of each part of the bonding layer 30 in contact with the laser the same, it is necessary to ensure that there is a certain relative angular velocity between the outer periphery of the bonding layer 30 and between the outer peripheries of the bonding layer 30 for the laser beam 41. When both the laser light source 40 and the processing table 60 rotate along the first rotation direction, the relative angular velocity between the bonding layer 30 and the laser is ω1 - ω2; when the laser light source 40 and the processing table 60 rotate in opposite directions, the relative angular velocity between the bonding layer 30 and the laser is ω1 + ω2. Similarly, in order to improve the uniformity of debonding, both ω1 - ω2 and ω1 + ω2 need to satisfy the above relationship.

[0058] In some preferred embodiments, the thickness range of the bonding layer 30 is between 1 μm and 50 μm. Further, the thickness range of the bonding layer 30 is between 5 μm and 30 μm.

[0059] In this embodiment, the bonding layer 30 should be selected as a bonding layer 30 that can be ablated or decomposed under the action of laser. For example, it can be a polyimide bonding layer, a rubber bonding layer, a cycloolefin copolymer bonding layer, a polyacrylate bonding layer, a polymethyl methacrylate bonding layer, a polyurethane bonding layer, a polycarbonate bonding layer, a polyethylene terephthalate bonding layer, a cellulose bonding layer, a polystyrene bonding layer, an epoxy resin bonding layer, a silicone bonding layer, a polyamide bonding layer, a UV-curable bonding layer, a polysulfone bonding layer, etc. The bonding layer 30 can also be a ceramic bonding layer or a metal bonding layer that is ablated or decomposed under the action of laser, or a combination of the above bonding layers 30.

[0060] Some prior arts have shown that when the laser light source 40 uses ultraviolet laser with a wavelength of 355 nm, after acting on acrylate (UV-curable bonding layer) for 10 - 100 ms, the acrylate decomposes. When using ultraviolet laser with a wavelength of 355 nm to act on polyurethane, the polyurethane decomposes in about 1 to 10 milliseconds. When using ultraviolet light to act on polyacrylate, generally the polyacrylate will decompose within 0.1 s to 10 s. And when using ultraviolet light to act on epoxy resin, the epoxy resin decomposes in about 100 ms to 10 s. Therefore, in some embodiments, according to the action of the common bonding layer 30 material and the laser, the dwell time value t is between 0.1 ms and 0.1 s. For example, when t is 0.1 ms, that is, at this time, the value of the relative angular velocity between the laser light source 40 and the bonding layer 30 can be between 1 / R1 and 1 / R1, and when R1 is 2 inches, the value of the relative angular velocity between the laser light source 40 and the bonding layer 30 is between 0.005 rad / s and 4.9 rad / s. It can be understood that the dissolution time of the bonding layer 30 is not only related to the material of the bonding layer 30, but also related to the energy of the laser and the distance between the laser and the bonding layer 30. Therefore, the dwell time t can be selected according to the actual situation. It is worth mentioning that although some bonding layers 30 will decompose within microseconds after contacting the laser, setting the dwell time at the millisecond level will not affect the decomposition and ablation of the bonding layer 30, but only increases the time for debonding. And if the dwell time is set at the nanosecond level, this will cause the rotation speed of the laser light source 40 or the processing table 60 to be too fast, resulting in an unstable debonding process. -3 / R1 to 1 / R1, and when R1 is 2 inches, the value of the relative angular velocity between the laser light source 40 and the bonding layer 30 is between 0.005 rad / s and 4.9 rad / s. It can be understood that the dissolution time of the bonding layer 30 is not only related to the material of the bonding layer 30, but also related to the energy of the laser and the distance between the laser and the bonding layer 30. Therefore, the dwell time t can be selected according to the actual situation. It is worth mentioning that although some bonding layers 30 will decompose within microseconds after contacting the laser, setting the dwell time at the millisecond level will not affect the decomposition and ablation of the bonding layer 30, but only increases the time for debonding. And if the dwell time is set at the nanosecond level, this will cause the rotation speed of the laser light source 40 or the processing table 60 to be too fast, resulting in an unstable debonding process.

[0061] In fact, experiments can be designed to measure the decomposition or ablation time of different bonding layers 30 under the action of a laser with different laser light sources 40. For example, when the energy of the laser and the distance between the laser and the bonding layer 30 are fixed, a high-speed camera (such as an SEM camera or an AFM camera) can be used to continuously capture the surface of the contact point between the laser and the bonding layer 30. After a certain period of action, the morphology of the bonding layer 30 between different frames captured by the high-speed camera can be used to analyze and obtain the decomposition or ablation time of the contact point between the bonding layer 30 and the laser. Of course, for some thermally soluble bonding layers 30, a thermal imager can be used for detection to calculate the decomposition or ablation time of the bonding layer 30. Finally, the dwell time is set to be less than or equal to the decomposition and ablation time of the bonding layer 30, thereby improving the debonding efficiency.

[0062] Furthermore, the wafer debonding method further includes: using a laser spot adjuster 50 to adjust the laser beam 41 so that the diameter of the spot of the laser beam 41 is less than or equal to the thickness of the bonding layer 30.

[0063] Specifically, the laser spot adjuster 50 can be devices such as a spot focuser, an aperture element, and a mirror. In fact, in this embodiment, adjusting the spot diameter of the laser beam 41 to be less than or equal to the thickness of the bonding layer 30 is to prevent the spot diameter of the laser beam 41 from being too large, which may cause damage to the wafer 10 when the laser beam 41 irradiates the wafer 10. In a specific embodiment, the diameter of the spot of the laser beam 41 is less than 99.9% of the thickness of the bonding layer 30. Preferably, the diameter of the spot of the laser beam 41 is less than 90% of the thickness of the bonding layer 30.

[0064] Furthermore, the wafer debonding method further includes: controlling the laser light source 40 to move along the height direction of the bonding layer 30 so that, in the thickness direction of the bonding layer 30, the spot of the laser beam 41 irradiating the bonding layer 30 is located between the surface where the bonding layer 30 contacts the wafer 10 and the surface of the carrier 20 facing away from the wafer 10.

[0065] In this embodiment, when controlling the laser light source 40 to move along the height direction of the bonding layer 30, it can be coordinated with a position controller 70 and an optical scanner. That is, the optical scanner is used to monitor the plane in space where the surface of the bonding layer 30 contacting the wafer 10 is located and the plane in space where the surface of the carrier 20 facing away from the wafer 10 is located, and control the movement of the position controller 70 according to the coordinate information between the two surfaces, thereby preventing the laser beam 41 from acting on the wafer 10.

[0066] Further, the steps after moving the moving laser light source 40 to the first plane in the height direction where the bonding layer 30 between the wafer 10 and the carrier 20 is located include: controlling the laser light source 40 to move in a direction close to or away from the bonding layer 30, so that the distance between the laser light source 40 and the geometric center of the bonding layer 30 is less than or equal to a first predetermined distance.

[0067] It should be noted that since the laser will attenuate after emission, when the distance between the laser light source 40 and the wafer 10 is too large, the energy of the laser irradiated on the bonding layer 30 is low, and the bonding layer 30 may not be decomposed or ablated. Therefore, it is necessary to make the distance between the laser light source 40 and the geometric center of the bonding layer 30 less than or equal to a first predetermined distance. In fact, the first predetermined distance needs to be determined according to the frequency, wavelength, pulse of the laser light source 40 and the focal position of the laser, so the first predetermined distance is not specifically limited in this embodiment.

[0068] Further, the focal length of the laser beam 41 is located within the bonding layer 30. If the diameter or maximum length of the wafer 10 is greater than twice the focal depth A of the laser beam 41, the steps after step S3 include: separating the remaining bonding layer 30 between the wafer 10 and the carrier 20 by at least one of direct cutting, gas cutting, solvent jet separation, ultrasonic vibration separation, thermal separation, and tensile separation.

[0069] See the appendix Figure 6As shown, the depth of focus refers to the axial distance near the focal length that maintains the spot size and laser energy. The laser spot size of the laser beam 41 remains almost the same within the depth of focus A, while the laser beam 41 diverges after the depth of focus A, resulting in a smaller laser spot and a decrease in the energy of the laser. If the diameter or maximum length of the wafer 10 is too large, this will cause the laser to be unable to completely dissolve or decompose the bonding layer 30 between the wafer 10 and the carrier 20. Therefore, in this embodiment, for the bonding layer 30 that cannot be dissolved or decomposed by the laser, it can be separated by mechanical cutting methods, such as direct cutting, gas cutting, and tensile separation. It can also be separated by chemical separation methods, such as solvent injection separation and heating separation processes to separate the bonding layer 30. Direct cutting means that the bonding layer 30 can be cut by a processing tool or wire; gas cutting means that the bonding layer 30 is cut by high-pressure gas; tensile separation means that by applying a tensile force to the wafer 10 and / or the carrier 20, the bonding layer 30 between the wafer 10 and the carrier 20 is separated; solvent injection separation means that by injecting a solvent that reacts with the bonding layer 30 to dissolve or separate the bonding layer 30; ultrasonic vibration separation means that by applying ultrasonic waves to the bonding layer 30 to separate the bonding layer 30; heating separation means that by applying high temperature to the bonding layer 30 to separate the bonding layer 30 from the wafer 10, and thermal slip debonding is included in the heating separation. In some embodiments, during the solvent injection separation process, a current can be applied at the contact point between the solvent and the bonding layer 30 to increase the reaction rate of the bonding layer 30. Of course, the focal length of the laser beam 41 can also be adjusted. As the debonding time progresses, the focal length of the laser beam 41 can be gradually adjusted in the direction closer to the geometric center of the wafer 10 until the laser completely ablates the bonding layer 30. The diameter or maximum length of the wafer 10 can be 2 inches, 3 inches, 4 inches, 5 inches, 6 inches, 7 inches, and 8 inches. In this embodiment, the depth of focus A of the laser can be 1 inch, 2 inches, and 3 inches. It can be understood that during the laser debonding process, the size of the depth of focus A of the laser is hardly affected by the wafer 10 or the carrier 20. The depth of focus A is determined by the wavelength of the laser, the beam waist radius of the laser, and the numerical aperture of the laser. Therefore, the adjustment of the depth of focus A can be achieved by adjusting the above parameters.

[0070] It should be noted that since the laser beam 41 near the depth of focus will diverge, that is, the spot size of the laser beam 41 may become larger, so that the laser beam 41 acts on the carrier 20 or the wafer 10. However, since the energy of the laser beam 41 near the depth of focus drops too much, it actually has little or no effect on the wafer 10 and the carrier 20.

[0071] It is worth mentioning that, in this embodiment, since the laser beam 41 directly acts on the bonding layer 30 and the spot size of the laser beam can be adjusted, the actual application scenario of the wafer debonding method of the present application is wider. For example, the method of the present application can be applied to the debonding of integrated circuit chips with a diameter or maximum length less than 50 mm or less than 30 mm, and will not affect the integrated circuit chips.

[0072] Since the laser in the present application does not need to act on the bonding layer 30 after passing through the carrier 20, the carrier 20 can include a light-transmitting carrier and a non-light-transmitting carrier, improving the selectivity of the carrier 20. Among them, the light-transmitting carrier includes at least one of a glass carrier, a quartz carrier, a diamond carrier, a silicon carbide carrier, and a sapphire carrier. The non-light-transmitting carrier includes at least one of a titanium carbide carrier, a silicon carrier, a ceramic carrier, a gallium arsenide carrier, an indium phosphide carrier, a gallium nitride carrier, a copper carrier, and a steel carrier. The ceramic carrier can be, for example, a titanium aluminum carbide carrier. It is worth mentioning that the use cost of the sapphire carrier and the silicon carbide carrier is relatively high, while although the glass carrier and the quartz carrier have low use costs and high hardness, the quartz carrier and the glass carrier are relatively brittle and are easily damaged by external forces. Preferably, the carrier 20 can adopt a copper carrier or a steel carrier with relatively strong structural strength and low cost. Of course, other high-performance composite material carriers can also be selected for the carrier, such as carbon fiber carriers and glass fiber carriers.

[0073] Since gases or impurities may be generated after the bonding layer 30 decomposes or ablates, these impurities may affect the wafer 10. Therefore, the steps after controlling the laser light source 40 to emit the laser beam 41 in this embodiment further include: controlling a gas to purge the contact point between the laser beam 41 and the bonding layer 30 to remove the gases or impurities generated by the decomposition or ablation of the bonding layer 30.

[0074] In a specific embodiment, the gas supply pipeline can be fixed on the position controller 70, and the gas supply pipeline is aligned with the action point of the laser beam 41 and the bonding layer 30, so that the gas can purge the gases or impurities generated by the bonding layer 30. In some embodiments, the gas used for purging can be selected from at least one of air, nitrogen, and argon. Using the above gases can assist in removing the gases or impurities generated after the laser ablation of the bonding layer 30 decomposes or ablates.

[0075] Furthermore, the step of fixing the wafer 10 and the carrier 20 includes: fixing at least one of the wafer 10 and the carrier 20, and applying a tensile force in the thickness direction of the bonding layer 30 to at least one of the wafer 10 and the carrier 20, and the directions of the tensile forces applied to the wafer 10 and the carrier 20 are opposite.

[0076] In a specific embodiment, a first suction cup 61 and a second suction cup 62 are provided on the processing table 60. The first suction cup 61 is used to fix the wafer 10, and the first suction cup 61 applies a pulling force to the wafer 10 in the thickness direction of the bonding layer 30. The second suction cup 62 is used to fix the carrier 20 and applies a pulling force to the carrier 20 in the thickness direction of the bonding layer 30, and the pulling forces applied by the first suction cup 61 and the second suction cup 62 are in opposite directions. This means that when debonding the bonding layer 30, the bonding layer 30 will be subjected to the pulling forces of the carrier 20 and the wafer 10, thereby assisting in separating the wafer 10 and the carrier 20 to a certain extent. On the other hand, when the first suction cup 61 applies a pulling force to the wafer 10, the wafer 10 will warp at a certain angle, thereby preventing the laser beam 41 from contacting the wafer 10 to a certain extent.

[0077] Further, the laser light source 40 includes at least one of an ultraviolet laser light source and an infrared laser light source; wherein, the wavelength λ1 of the laser beam 41 of the ultraviolet laser light source satisfies the relationship: 10 nm ≤ λ1 ≤ 400 nm. The wavelength λ2 of the laser beam 41 of the infrared laser light source satisfies the relationship: 1 μm ≤ λ2 ≤ 11 μm.

[0078] Thanks to the design of the present application, that is, the laser can directly contact the bonding layer 30, which means that there is no need to consider the influence of the laser on the carrier 20. Therefore, the selection range of the laser is increased. When the laser light source 40 uses an ultraviolet laser light source, the wavelength λ1 of the laser beam 41 of the ultraviolet laser light source can be 10 nm, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, and 400 nm. Of course, an infrared laser light source can also be used to cooperate with the thermoplastic or thermosetting bonding layer 30, and the wavelength λ2 of the laser beam 41 of the infrared laser light source can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, and 11 μm. Of course, the laser light source 40 can also use an excimer laser light source, that is, it can be an ArF laser, a KrF laser, an XeCl laser, an XeF laser, and an F2 laser.

[0079] In summary, the wafer debonding method of the present application directly contacts the bonding layer 30 through the laser, and there is no need for the laser to pass through the carrier 20 and then act on the bonding layer 30, thereby improving the selectivity of the carrier 20, that is, the carrier 20 can use a light-transmitting carrier 20 or an opaque carrier 20. In addition, in the present application, by setting the laser light source 40 or the processing table 60 to rotate, and limiting the relative angular velocity between the laser light source 40 and the bonding layer 30, the laser light source 40 can be uniformly in contact with various locations on the periphery of the bonding layer 30, ensuring the uniform decomposition or ablation of the bonding layer 30, and improving the efficiency of debonding. On the other hand, in this embodiment, by limiting the spot size of the laser beam 41 to be less than or equal to the thickness of the bonding layer 30, it is avoided that the spot size of the laser beam 41 is too large, which causes the laser beam 41 to irradiate the wafer 10 and cause damage to the wafer 10. At the same time, the present application also performs gas purge at the contact point between the laser and the bonding layer 30 to prevent the gas and impurities generated after the decomposition or ablation of the bonding layer 30 from affecting the wafer 10. Finally, thanks to the design that the laser directly acts on the bonding layer 30, the laser light source 40 in this embodiment can use an ultraviolet laser light source or an infrared laser light source, and the selectivity of the bonding layer 30 is also greatly improved.

[0080] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0081] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of this application.

[0082] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A wafer debonding method for debonding a wafer (10) fixed on a carrier (20), wherein the wafer (10) is fixed to the carrier (20) through a bonding layer (30), and is characterized in that, The wafer debonding method includes: Step S1: Mount the wafers (10) and the carrier (20) fixed together on the processing table (60); Step S2: Move the laser light source (40) to the first plane in the height direction where the bonding layer (30) is located, and adjust the laser light source (40) so that the laser beam (41) emitted by the laser light source (40) irradiates on the bonding layer (30) in a direction perpendicular to the thickness direction of the bonding layer (30); Step S3: Control the laser light source (40) to rotate in the first plane with the bonding layer (30) as the center and / or control the processing table (60) to rotate self - clockwise, so as to at least partially decompose or at least partially ablate the bonding layer (30) by using the laser beam (41) emitted by the laser light source (40).

2. The wafer debonding method according to claim 1, characterized in that The step of controlling the laser light source (40) to rotate in the first plane with the bonding layer (30) as the center and / or controlling the processing table (60) to rotate self - clockwise includes: Control the laser light source (40) to rotate in a first plane around the bonding layer (30) at a first rotational angular velocity ω1, where the value of the first rotational angular velocity ω1 satisfies the relation: 10 -7 / (R1*t) ≤ ω1 ≤ 10 -4 / (R1*t), R1 represents the radius of the wafer (10) or half of the maximum length of the wafer (10), and t represents the time when the laser stays at various positions on the bonding layer (30); or, Control the processing table (60) to rotate about its own axis at a second rotational angular velocity ω2, where the value of the second rotational angular velocity ω2 satisfies the relation: 10 -7 / (R1*t) ≤ ω2 ≤ 10 -4 / (R1*t), where R1 represents the radius of the wafer (10) or half of the maximum length of the wafer (10), and t represents the time for which the laser stays at each location on the bonding layer (30).

3. The wafer debonding method according to claim 1, wherein, The step of controlling the laser light source (40) to rotate in the first plane with the bonding layer (30) as the center and / or controlling the processing table (60) to rotate self - clockwise includes: Control the laser light source (40) to rotate in the first plane along the first rotation direction with the bonding layer (30) as the center, and control the processing table (60) to rotate self - clockwise along the second rotation direction opposite to the first rotation direction or rotate self - clockwise along the first rotation direction, and the angular velocity ω1 of the laser light source (40) is different from the angular velocity ω2 of the wafers (10) and the carrier (20); When the laser light source (40) and the processing table (60) both rotate in the first rotation direction, the numerical value of the angular velocity ω1 of the laser light source (40) and the numerical value of the angular velocity ω2 of the processing table (60) satisfy the relational expression: 10 -7 / (R1*t) ≤ ω1 - ω2 ≤ 10 -4 / (R1*t); when the laser light source (40) and the processing table (60) rotate in opposite directions, the numerical value of the angular velocity ω1 of the laser light source (40) and the numerical value of the angular velocity ω2 of the processing table (60) satisfy the relational expression: 10 -7 / (R1*t) ≤ ω1 + ω2 ≤ 10 -4 / (R1*t), where R1 represents the radius of the wafer (10) or half of the maximum length of the wafer (10), and t represents the time for the laser to stay at each position on the bonding layer (30).

4. The wafer debonding method according to claim 1, wherein The wafer debonding method further includes: Adjust the laser beam (41) by using a laser spot regulator (50) so that the diameter of the spot of the laser beam (41) is less than or equal to the thickness of the bonding layer (30); and / or, Control the laser light source (40) to move along the height direction of the bonding layer (30) so that, in the thickness direction of the bonding layer (30), the spot of the laser beam (41) irradiating on the bonding layer (30) is located between the surface where the bonding layer (30) contacts the wafers (10) and the surface of the carrier (20) facing away from the wafers (10).

5. The wafer debonding method according to any one of claims 1 to 4, characterized in that, The steps after moving the laser light source (40) to the first plane in the height direction where the bonding layer (30) between the wafers (10) and the carrier (20) is located include: Control the laser light source (40) to move in a direction close to or away from the bonding layer (30) so that the distance between the laser light source (40) and the geometric center of the bonding layer (30) is less than or equal to a first predetermined distance.

6. The wafer debonding method according to any one of claims 1 to 4, characterized in that, The focal length of the laser beam (41) is located within the bonding layer (30). If the diameter or the maximum length of the wafers (10) is greater than twice the depth of focus A of the laser beam (41), the steps after step S3 include: Separate the remaining bonding layer (30) between the wafers (10) and the carrier (20) by at least one of direct cutting, gas cutting, solvent jet separation, ultrasonic vibration separation, heat separation, and tensile separation.

7. The wafer debonding method according to any one of claims 1 to 4, characterized in that, The carrier (20) includes a light-transmitting carrier and a non-light-transmitting carrier; Among them, the light-transmitting carrier includes at least one of a glass carrier, a quartz carrier, a diamond carrier, a silicon carbide carrier, and a sapphire carrier; The non-light-transmitting carrier includes at least one of a titanium carbide carrier, a silicon carrier, a gallium arsenide carrier, an indium phosphide carrier, a gallium nitride carrier, a ceramic carrier, a copper carrier, and a steel carrier.

8. The wafer debonding method according to any one of claims 1 to 4, characterized in that, The steps after controlling the laser light source (40) to emit the laser beam (41) further include: Controlling a gas to purge the contact point of the laser beam (41) and the bonding layer (30) to remove gases or impurities generated when the bonding layer (30) decomposes or ablates.

9. The wafer debonding method according to any one of claims 1 to 4, characterized in that, The steps of fixing the wafer (10) and the carrier (20) include: Fixing at least one of the wafer (10) and the carrier (20), and applying a tensile force along the thickness direction of the bonding layer (30) to at least one of the wafer (10) and the carrier (20), and the directions of the tensile forces applied to the wafer (10) and the carrier (20) are opposite.

10. The wafer debonding method according to any one of claims 1 to 4, characterized in that, The laser light source (40) includes at least one of an ultraviolet laser light source and an infrared laser light source; Among them, the wavelength λ1 of the laser beam (41) of the ultraviolet laser light source satisfies the relationship: 10 nm ≤ λ1 ≤ 400 nm; and / or, The wavelength λ2 of the laser beam (41) of the infrared laser light source satisfies the relationship: 1 μm ≤ λ2 ≤ 11 μm.

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