Method for laser debonding and applications thereof

Abstract

The application discloses a laser debonding method and application thereof, and the method comprises the following steps: (1) a laser emitter is used to irradiate a target area of a bonded wafer pair with a light beam, so that a bonding layer is decomposed and / or modified; a carrier wafer and a device wafer are separated; (2) a defocusing mode of the laser emitter is used to irradiate a photosensitive bonding material remaining on the surface of the separated device wafer with a light beam; in step (1), a single pulse energy density of the light beam irradiation is greater than an ablation threshold of the photosensitive bonding material; in step (2), a single pulse energy density of the light beam irradiation is less than the ablation threshold of the photosensitive bonding material. The application has the advantages of simple operation, cost saving, space saving, high processing efficiency, good universality, programmable integrated processing and the like, and the prepared ultra-thin device wafer surface can be completely degummed, which is beneficial to realize large-scale application.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor processing, and particularly relates to a laser debonding method and application thereof. BACKGROUND

[0002] With the development of miniaturization, portability and multifunction of integrated electronic devices, the semiconductor packaging technology is rapidly developed from 2D structure to 2.5D and even 3D structure, which will inevitably put forward higher requirements for high-density integration and heterogeneous structure packaging of system-in-package. As a key technology in the wafer-level chip thinning process, temporary bonding / debonding is crucial for maintaining the integrity of ultra-thin wafers in advanced semiconductor processes. Due to the instantaneous high temperature and high pressure during laser debonding, the carbon ash generated by the response material photolysis is densely covered on the surface of the residual glue, making it difficult for cleaning agents to enter the interior of the residual glue. In addition, the instantaneous high temperature makes the surface-modified residual glue invalid to the cleaning agent. Therefore, it is difficult to clean the residual glue on the ultra-thin device after laser debonding. Although the high-pressure cleaning method can clean it away, this method is easy to cause damage to the ultra-thin device. Therefore, it is urgent to develop a simple, efficient, low-cost and safe and reliable method for cleaning residual glue on a large scale in the laser debonding process. SUMMARY

[0003] In view of the above technical problems, the present application provides a laser debonding method and application thereof, which has the advantages of simple operation, cost saving, space saving, high processing efficiency, good universality and programmable integrated processing, and the wafer surface of the ultra-thin device prepared can be completely degummed, which is beneficial to realize large-scale application.

[0004] To achieve the above object, the technical scheme adopted by the present application is as follows:

[0005] On the one hand, the present application provides a laser debonding method, which is applied to the debonding of a bonding layer formed by a carrier wafer, a device wafer and a photosensitive bonding material, and the method comprises the following steps:

[0006] (1) using the focusing mode of a laser emitter to irradiate a target area of the bonded wafer pair with a light beam to cause the bonding layer to decompose and / or modify; separating the carrier wafer and the device wafer;

[0007] (2) using the defocusing mode of the laser emitter to irradiate the photosensitive bonding material remaining on the surface of the separated device wafer with a light beam;

[0008] In step (1), the single-pulse energy density of the light beam irradiation is greater than the ablation threshold of the photosensitive bonding material; in step (2), the single-pulse energy density of the light beam irradiation is less than the ablation threshold of the photosensitive bonding material.

[0009] In the technical scheme of the present application, a laser emitter is used to irradiate the bonding layer with a light beam, so that the photosensitive bonding material is decomposed and / or modified, and a gas or plasma impact effect is generated.

[0010] As a preferred embodiment, in step (2), the power of the laser emitter is 3-100 W.

[0011] Preferably, the repetition frequency of the laser emitter is 20-1000 kHz.

[0012] Preferably, the scanning speed of the laser emitter is 1000-5000 mm / s.

[0013] Preferably, the laser is an ultraviolet laser.

[0014] As a preferred embodiment, in step (2), the defocus is selected from positive defocus or negative defocus; during the light beam irradiation, the relative displacement between the galvanometer and the processing platform can be adjusted by program control to control the appropriate defocus amount.

[0015] Preferably, the defocus amount is 10-50 mm.

[0016] Preferably, the single-pulse energy density of the light beam irradiation is 10-200 mJ / cm 2 ;

[0017] Preferably, the scanning pitch of the light beam irradiation is 0.2-5 mm.

[0018] Preferably, the defocused spot area of the light beam irradiation is 0.1-10 mm 2 ;

[0019] Preferably, the light beam irradiation is performed at least once; in the technical scheme of the present application, in step (2), the parameters of the light beam irradiation are adjusted according to the distribution position of the wafer surface residue; due to the influence of subsequent process procedures (acid-base wet cleaning, wet etching, dry etching, and electroplating, etc.) on the photosensitive bonding material on the device wafer surface, more residue is inevitably left during the debonding process, and multiple scanning can be performed.

[0020] As a preferred embodiment, the bonded wafer is obtained by thermocompression bonding of a carrier wafer coated with a photosensitive response adhesive and a device wafer coated with a bonding adhesive; after the thermocompression bonding, the device wafer is further thinned and subjected to semiconductor processing.

[0021] As a preferred embodiment, step (2) further comprises post-processing; the post-processing is cleaning; specifically, the photosensitive bonding material remaining on the surface of the separated device wafer is cleaned using a cleaning agent in a cleaning chamber.

[0022] As a preferred embodiment, in step (1), the repetition frequency of the laser emitter is 20-1000 kHz.

[0023] Preferably, the scanning speed of the laser emitter is 1000-5000 mm / s.

[0024] Preferably, the laser is an ultraviolet laser.

[0025] As a preferred embodiment, in step (1), the single-pulse energy density of the beam irradiation is greater than 200 mJ / cm 2 .

[0026] In some specific embodiments, the laser emitters in steps (1) and (2) are the same laser emitter, and the use of a laser emitter with different parameters can further reduce costs, reduce the size of the instrument, and achieve integrated processing of cleaning residual glue and debonding.

[0027] In the technical solution of the present application, in step (2), the cavitation and erosion effect of the ultraviolet laser is used to destroy the chemical bonds in the modified residual glue to cavitate the residual glue inside the device wafer surface and produce micro-holes, so that the cleaning agent can easily enter the inside of the residual glue and quickly dissolve; the single-pulse energy density of the beam irradiation needs to be less than the ablation threshold of the photosensitive bonding material and the device wafer at the same time; compared with the laser parameters in the debonding process in step (1), there is no obvious gas or plasma impact effect under the laser parameters in step (2). In addition, the low energy density under the defocusing irradiation in step (2) makes the instantaneous maximum temperature of the irradiation area also lower than the temperature of the photosensitive material at the focal point under the debonding laser parameters, so the device wafer is not damaged.

[0028] In another aspect, the present application provides the use of the above method in electronic packaging, preferably in wafer temporary bonding / debonding.

[0029] Preferably, the use is in ultra-thin wafer temporary bonding / debonding; the thickness of the ultra-thin wafer is ≤200 μm.

[0030] The above technical solution has the following advantages or beneficial effects:

[0031] The present application provides a laser debonding method for the debonding of photosensitive material temporary bonding, which is based on the interaction between laser and material, different laser processing parameters are preset in the same laser processing equipment, and an integrated processing program is executed. After aging laser parameter processing, it is easy to realize the integrated cleaning of the ultra-thin device wafer surface, which has the advantages of simple operation, cost saving, space saving, high processing efficiency, good universality, programmable integrated processing, etc. The prepared device wafer has no bonding glue residue and the wafer surface is not damaged. Attached Figure Description

[0032] Figure 1 This is a flowchart of laser debonding in Embodiment 1 of the present invention.

[0033] Figure 2 This is a morphology diagram of the bonding adhesive on the surface of the ultrathin device wafer obtained in step S3 of embodiment 1 of the present invention.

[0034] Figure 3 This is a schematic diagram of the laser beam processing method in step S4 of embodiment 1 of the present invention.

[0035] Figure 4 This is a morphology diagram of the cavitation residue on the surface of the ultrathin device wafer obtained in step S4 of embodiment 1 of the present invention.

[0036] Figure 5 This is a topographic image of the surface of the ultrathin device wafer obtained after cleaning in step S5 of Embodiment 1 of the present invention, showing that there is no residual adhesive and no damage.

[0037] Figure 6 This is a morphological diagram of the surface of the ultra-thin device wafer with a small amount of residual adhesive, as shown in Embodiment 1 of the present invention. Detailed Implementation

[0038] The following embodiments are merely some, not all, of the embodiments of the present invention. Therefore, the detailed descriptions of the embodiments provided below are not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0039] In this invention, unless otherwise specified, all equipment and raw materials are commercially available or commonly used in the industry. The methods described in the following embodiments are conventional methods in the art, unless otherwise specified.

[0040] Example 1:

[0041] like Figure 1 As shown, the laser debonding method in this embodiment includes the following steps:

[0042] S1. The carrier wafer 1 coated with photosensitive responsive adhesive (Shenzhen Huaxun WLP LB210) 2 and the device wafer 4 coated with bonding adhesive (Shenzhen Huaxun WLP TB4130) 3 are hot-pressed to fix the device wafer 4 on the carrier wafer 1, and the photosensitive responsive adhesive 2 and the bonding adhesive 3 form a photosensitive responsive material layer.

[0043] S2. Under the premise that the supporting wafer 1 provides support, the back side of the device wafer 4 is thinned and subsequent semiconductor manufacturing processes are carried out to obtain an ultra-thin device wafer 5.

[0044] S3, execute the debonding laser parameter program, the preset debonding laser parameter is a single pulse energy density of the light beam 600 mJ / cm 2 , the focused light beam size is 50 μm x 600 μm, the focal length is 511 mm, the photosensitive response material layer is at the focal point, and the scanning interval is 50 μm; the debonding is performed at the focal point position by irradiation of the above-mentioned ultraviolet laser beam, and then the ultrathin device wafer 6 with residual bonding glue is separated (the surface topography diagram is shown in Figure 2 ) ;

[0045] S4, as shown in Figure 3 , the vertical movement of the galvanometer head is adjusted (it should be noted that the laser emitter used in the embodiment can adjust the height position of the galvanometer through the lifting table, or adjust the height position of the three-dimensional worktable through the Z-axis), so that the ultrathin device wafer 6 with residual bonding glue is at different defocus positions of the laser emitter: the galvanometer head is moved upward by 15 mm so that the residual glue layer is at a position of positive defocus 15 mm, and the parameters of the laser emitter are set as follows: a single pulse energy density of the light beam is 100 mJ / cm 2 , the defocus light beam size is 200 μm x 2400 μm, the residual glue layer is at a position of positive defocus 15 mm, and the scanning interval is 200 μm; then the residual bonding glue on the surface of the ultrathin device wafer 6 is irradiated by the ultraviolet laser beam to accelerate cavitation to obtain the device wafer 7 with cavitated residual glue (the surface topography diagram of the residual glue is shown in Figure 4 ) ;

[0046] S5, the device wafer 7 with cavitated residual glue is moved to the cleaning chamber through the transfer disc, and is cleaned by the cleaning agent for 3 min to obtain the device wafer 8 without residual glue and damage (the surface topography is shown in Figure 5 ) ;

[0047] S6, finally, the device wafer 8 with completely removed glue is processed to prepare the ultrathin chip 9.

[0048] After the above steps are performed, the device wafer 9 with completely removed residual glue can be obtained after processing, which is expected to be scaled and applied in the temporary debonding process in the high-end chip thinning process.

[0049] Figure 6 The surface topography of the device wafer obtained by directly cleaning with the cleaning agent for 3 min without step S4 is shown in Figure 6 and Figure 5 It can be seen that, Figure 6In the middle, the wafer surface still remains some bonding glue difficult to remove, which is caused by carbon ash covering and material modification in the process of debonding. The device wafer surface obtained after the cavitation laser parameter processing and cleaning in S4 is very clean, without obvious residual glue and damage.

[0050] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make some improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered within the protection scope of the present application.

Claims

1. A laser debonding method, applied to the debonding of an adhesive layer formed by a carrier wafer, a device wafer, and a photosensitive material, characterized in that, The method includes the following steps: (1) Using the focusing mode of a laser emitter, the beam is irradiated onto the target area of ​​the bonded wafer pair, causing the adhesive layer to decompose and / or be modified; the carrier wafer and the device wafer are separated. (2) The defocusing mode of the laser emitter is used to irradiate the photosensitive bonding material remaining on the surface of the separated device wafer with a laser beam; In step (1), the single-pulse energy density of the beam irradiation is greater than the ablation threshold of the photosensitive bond and the material; in step (2), the single-pulse energy density of the beam irradiation is less than the ablation threshold of the photosensitive bond and the material.

2. According to the method of claim 1, in step (2), the power of the laser emitter is 3 to 100W.

3. According to the method of claim 1, in step (2), the repetition frequency of the laser emitter is 20 to 1000 kHz.

4. According to the method of claim 1, in step (2), the scanning speed of the laser emitter is 1000-5000 mm / s.

5. The method according to claim 1, wherein in step (2), the laser is an ultraviolet laser.

6. In the method according to claim 1, in step (2), the defocus is selected from positive defocus or negative defocus.

7. According to the method of claim 1, in step (2), the defocusing amount is 10-50mm.

8. The method of claim 1, wherein the single pulse energy density of the light beam irradiation in step (2) is 10-200 mJ / cm 2 .

9. According to the method of claim 1, in step (2), the scanning spacing of the beam irradiation is 0.2 to 5 mm.

10. The method of claim 1, wherein the defocused spot size of the light beam irradiation in step (2) is 0.1-10 mm 2 .

11. The method according to claim 1, wherein in step (2), the beam irradiation is performed at least once.

12. The method according to claim 1, wherein the bonding wafer is obtained by thermo-press bonding a carrier wafer coated with photosensitive responsive adhesive and a device wafer coated with bonding adhesive; the thermo-press bonding further includes the steps of thinning and semiconductor processing of the device wafer.

13. The method according to claim 1, wherein step (2) further includes post-processing; the post-processing is cleaning.

14. The method according to claim 1, wherein in step (1), the repetition frequency of the laser emitter is 20 to 1000 kHz.

15. The method according to claim 1, wherein in step (1), the scanning speed of the laser emitter is 1000-5000 mm / s.

16. The method according to claim 1, wherein in step (1), the laser is an ultraviolet laser.

17. The method of claim 1, wherein in step (1), the single pulse energy density of the beam irradiation is greater than 200 mJ / cm 2 .

18. The method according to claim 1, wherein the laser emitter in steps (1) and (2) is the same laser emitter.

19. The application of the method according to any one of claims 1-18 in electronic packaging, characterized in that, Applications in temporary bonding / debonding of wafers.

20. The application according to claim 19, characterized in that, Application in temporary bonding / debonding of ultrathin wafers; the thickness of the ultrathin wafers is ≤200μm.

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