Bonding wafer de-bonding method

Abstract

The invention relates to a method for de-bonding a bonding wafer. The bonding sheet comprises a wafer, and the wafer comprises a silver-plated surface and a device surface which are oppositely arranged. The carrier is bonded with the device surface through a bonding dielectric layer; the method for de-bonding the bonding sheet comprises the following steps of: arranging a high-temperature-resistant film on the silver-plated surface; carrying out thermal slip de-bonding, and separating the wafer from the carrier; and removing the high-temperature-resistant film. According to the invention, the high-temperature-resistant protective layer is arranged on the silver-plated surface before thermal slippage de-bonding, so that the silver layer of the silver-plated surface is physically isolated from air, the silver layer is prevented from being oxidized in the thermal slippage de-bonding process, the cleanliness of the silver layer is ensured, and the performance stability and reliability of the device are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor technology, and particularly relates to a method for debonding a bonded wafer. BACKGROUND

[0002] In the field of semiconductor manufacturing, wafer temporary bonding and debonding are extremely critical process flows, which play an indispensable role in realizing high performance and miniaturization of chips. When a thermal slip debonding process is used, the temperature usually reaches 150 DEG C to 300 DEG C, or even higher, during the debonding process. Under such high temperature conditions, the chemical properties of silver become more active, and the silver layer on the back surface of the wafer will chemically react with oxygen in the air and gradually be oxidized. The oxidation of the back silver will cause obvious color difference problems in appearance, and will also affect subsequent chip packaging and soldering.

[0003] The method for improving silver oxidation by soaking an organic antioxidant in the prior art is prone to cause residue of impurities, which will adversely affect the subsequent process. SUMMARY

[0004] In view of the deficiencies in the prior art, the present application aims to provide a method for debonding a bonded wafer. A high-temperature-resistant protective layer is provided on the silver-plated surface before thermal slip debonding, so as to physically isolate the silver-plated surface from the air, avoid oxidation of the silver layer on the silver-plated surface during thermal slip debonding, and ensure the cleanliness of the silver layer, thereby improving the performance stability and reliability of the device.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] In a first aspect, the present application provides a method for debonding a bonded wafer, wherein the bonded wafer comprises a wafer, and the wafer comprises a silver-plated surface and a device surface arranged oppositely.

[0007] A carrier is bonded to the device surface through a bonding medium layer.

[0008] The method for debonding the bonded wafer comprises the following steps:

[0009] A high-temperature-resistant film is provided on the silver-plated surface.

[0010] Thermal slip debonding is performed to separate the wafer from the carrier.

[0011] The high-temperature-resistant film is removed.

[0012] In the present application, the device surface of the wafer refers to the side surface on which an integrated circuit is arranged.

[0013] The high-temperature-resistant film provided on the silver-plated surface should be able to withstand high temperature in the process of thermal slip debonding, effectively isolate the contact of oxygen with the silver-plated surface, and have a certain thickness. The method of providing the high-temperature-resistant film on the silver-plated surface can be mechanical film or manual film, and the uniform adhesion of the wafer and the high-temperature-resistant film is realized by pressure (roller or vacuum).

[0014] Optionally, the heat-resistant temperature of the high-temperature-resistant film is above 220°C, for example, it can be 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, 320°C, 330°C, 340°C or 350°C, including but not limited to the listed values, and the remaining values within the range are also applicable.

[0015] Optionally, the elongation at break of the high-temperature-resistant film is less than 5%, for example, it can be 1%, 2%, 3%, 4% or 5%, including but not limited to the listed values, and the remaining values within the range are also applicable.

[0016] Optionally, the thickness of the high-temperature-resistant film is 20μm~100μm, for example, it can be 20μm, 22μm, 33μm, 44μm, 55μm, 66μm, 77μm, 88μm, 99μm or 100μm, including but not limited to the listed values, and the remaining values within the range are also applicable.

[0017] Optionally, the tensile strength of the high-temperature-resistant film is 100MPa~150MPa, for example, it can be 100MPa, 105MPa, 110MPa, 115MPa, 120MPa, 125MPa, 130MPa, 135MPa, 140MPa, 145MPa or 140MPa, including but not limited to the listed values, and the remaining values within the range are also applicable.

[0018] Optionally, the oxygen permeability of the high-temperature-resistant film is 0.01 cc / (m 2 ·day·bar)~0.5cc / (m 2 ·day·bar), for example, it can be 0.01 cc / (m 2 ·day·bar), 0.05 cc / (m 2 ·day·bar), 0.1 cc / (m 2 ·day·bar), 0.15 cc / (m 2 ·day·bar), 0.2 cc / (m 2 ·day·bar), 0.25 cc / (m 2 ·day·bar), 0.3 cc / (m2 ·day·bar), 0.35 cc / (m 2 ·day·bar), 0.4 cc / (m 2 ·day·bar), 0.45 cc / (m 2 ·day·bar) or 0.5 cc / (m 2 (day / bar), including but not limited to the listed values, and the other values ​​in the range also apply.

[0019] In this invention, the adhesive used to apply the high-temperature resistant film to the silver-plated surface should have low viscosity and be easily soluble. The adhesive needs to have a certain viscosity to ensure the high-temperature resistant film adheres firmly to the silver-plated surface, thereby effectively protecting the silver-plated surface. It should also ensure that the high-temperature resistant film can be easily removed from the silver-plated surface after debonding.

[0020] Optionally, the high-temperature resistant film includes either a homopolymer polyimide film or a cyclopolymer polyimide film.

[0021] Optionally, the high-temperature resistant film can be applied to the silver-plated surface by using an adhesive.

[0022] Optionally, the high-temperature resistant film removal method includes: setting a protective film on the device side of the wafer; fixing the high-temperature resistant film on the silver-plated surface, moving the wafer to separate from the high-temperature resistant film, removing the high-temperature resistant film, cleaning the adhesive; and removing the protective film.

[0023] Optionally, the viscosity of the adhesive is 500 mPa·s to 10000 mPa·s, for example, it can be 500 mPa·s, 600 mPa·s, 700 mPa·s, 1000 mPa·s, 1500 mPa·s, 2000 mPa·s, 3000 mPa·s, 5000 mPa·s, 8000 mPa·s or 10000 mPa·s, including but not limited to the listed values, and other values ​​within the range are also applicable.

[0024] Optionally, the adhesive includes a one-component acrylate adhesive, an epoxy resin adhesive, or a silicone-based adhesive, wherein the main component of the silicone-based adhesive is a siloxane.

[0025] In this invention, before removing the high-temperature resistant film from the silver-plated surface, a protective film is used to protect the device surface of the wafer to prevent solvent contamination of the wafer during the cleaning of the adhesive.

[0026] Optionally, the solvent used to clean the adhesive includes any one or a combination of at least two of isopropanol, acetone, or ethanol.

[0027] Optionally, the method of cleaning the adhesive includes ultrasonic cleaning.

[0028] Optionally, the protective film includes any one of a UV film, a polyethylene terephthalate film, a polyethylene film, or a polyimide film.

[0029] Optionally, the material of the high-temperature resistant film includes a high-temperature UV resistant film.

[0030] Optionally, the high-temperature resistant UV film can be applied to the silver-plated surface by spin coating.

[0031] In this invention, compared to homopolymer polyimide films or cyclopolymer polyimide films, the high-temperature resistant UV film is directly spin-coated onto the silver-plated surface without the need for an adhesive. After debonding, the high-temperature resistant UV film can be cured under ultraviolet light (UV light) exposure to form a cross-linked 3D network structure, resulting in the loss or weakening of adhesion to the silver-plated surface. This allows for the separation of the high-temperature resistant UV film from the silver-plated surface, which can be removed manually or by equipment by peeling off the film, thus eliminating the need for cleaning the adhesive.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] This invention pre-defines a high-temperature resistant protective layer on the silver-plated surface of the wafer before thermal slip debonding, thereby isolating the silver-plated surface from the air, preventing the silver layer on the silver-plated surface from being oxidized during the thermal slip debonding process, ensuring the cleanliness of the silver layer, and thus improving the performance stability and reliability of the device. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the bonding sheet structure in a specific embodiment of the present invention.

[0035] Figure 2 This is a schematic diagram of the structure of a bonded sheet after a homopolymer polyimide film is applied to the surface of a silver-plated layer in a specific embodiment of the present invention.

[0036] Figure 3 This is a schematic diagram of the structure after a UV protective film is applied to the wafer device surface in a specific embodiment of the present invention.

[0037] Wherein: 1-Wafer; 11-Silver plating layer; 12-Device surface; 2-Carrier; 3-Bonding dielectric layer; 4-Quartz film; 5-UV protective film. Detailed Implementation

[0038] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0039] The "range" disclosed in this invention can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. This type of range definition can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be arbitrarily combined, meaning any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0040] In this invention, "a combination of at least two" refers to a quantity greater than or equal to two, unless otherwise specified. For example, "any combination of one or at least two" means one or more or more items. It can be understood that when referring to "a combination of at least two," it refers to any suitable combination of multiple items, that is, a combination of "at least two" items carried out in a manner that does not conflict with and enables the implementation of this invention.

[0041] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0042] The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0043] Those skilled in the art will understand that the order in which the steps are written in the methods of the various embodiments does not imply a strict execution order. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, but are preferably performed sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), meaning that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0044] In this invention, open-ended technical features or solutions described using terms such as "comprising" do not exclude additional members beyond those listed unless otherwise specified. They can be considered as providing both closed-ended features or solutions comprised of the listed members and open-ended features or solutions that include additional members beyond the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or exclude additional members. This can be considered as providing both technical features or solutions where "A is composed of a1, a2, and a3" or "A is selected from a1, a2, and a3," and technical features or solutions where "A includes not only a1, a2, and a3, but also other members."

[0045] In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" represents a group consisting of A, B, and "a combination of A and B". "Containing A and / or B" can mean "containing A, containing B, and containing A and B", or "containing A, containing B, or containing A and B", and can be appropriately understood according to the context.

[0046] In this invention, "optional" means that something is optional, that is, it refers to either "with" or "without". If there are multiple "optional" options in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, then each "optional" option is independent.

[0047] In this invention, the method of thermal slip debonding is not particularly limited. Any improvement of the thermal slip debonding process according to actual technical requirements is applicable to the debonding method of this invention. To further illustrate the technical solution of the specific embodiments of this invention, the thermal slip debonding method used in the specific embodiments of this invention includes, but is not limited to, the following steps:

[0048] A download tray is placed above the heating platform to adsorb the bonded wafer, while an upper suction cup is placed below the heating platform to adsorb the carrier wafer. In a vacuum environment, the bonded wafer is heated by the simultaneous action of the upper and lower heating platforms, which weakens the chemical bonds and reduces the bonding strength, softening the bonding medium layer between the wafer and the carrier. A horizontal sliding rail drives the download stage to slide the wafer horizontally until it is pulled out of the outer edge of the carrier wafer, thereby achieving the separation of the wafer and the carrier wafer. The download tray adsorbs the wafer to the cleaning module in the equipment, and the bonding medium remaining on the wafer surface is cleaned.

[0049] In one specific embodiment of the present invention, a method for debonding bonded sheets is provided, such as... Figure 1 As shown, the bonding sheet includes a wafer 1, the wafer including a silver-plated surface 11 and a device surface 12 opposite to the silver-plated surface 11; a carrier 2, the carrier being bonded to the device surface 12 through a bonding dielectric layer 3; the method for debonding the bonding sheet includes the following steps:

[0050] like Figure 2 As shown, a single-component acrylate adhesive with a viscosity of 550 mPa·s was used to bond a 33 μm thick homopolymer polyimide film 4 with an oxygen permeability of 0.01 cc / (m²·day·bar) to the silver-plated surface 11. The tensile strength between the homopolymer polyimide film 4 and the silver-plated surface was 110 MPa. Thermal slip debonding was used to separate the wafer 1 from the carrier 2. For example... Figure 3 As shown, a UV protective film 5 is applied to the device side of the wafer to protect it. Then, the homopolymer polyimide film 4 is removed, and the residual single-component acrylate adhesive is cleaned with isopropanol. The isopropanol is then dried with nitrogen. Finally, the UV film is cured under ultraviolet light, and the UV protective film 5 is removed.

[0051] Based on the above embodiments, in another specific embodiment of the present invention, the high-temperature resistant film is a cyclic polyimide film with a thickness of 45 μm, an oxygen permeability of 0.02 cc / (m²·day·bar), and a heat resistance temperature of 260℃. The debonding method includes:

[0052] Using a silicon-based adhesive with a viscosity of 6000 mPa·s, the cyclophenyl polyimide film was bonded to the silver-plated surface using thermal slip bonding to separate the wafer from the carrier. A polyethylene film was then bonded to the device side of the wafer as a protective film. The polyimide film was then peeled off from the silver-plated surface. The residual silicon-based adhesive was washed with ethanol, and the solvent was dried with nitrogen. Finally, the polyethylene film was removed.

[0053] Based on the above embodiments, in another specific embodiment of the present invention, the high-temperature resistant film is made of a high-temperature resistant UV film, and the method for unbonding the bonding sheet includes the following steps:

[0054] A high-temperature resistant UV film with a thickness of 30 μm and an oxygen permeability of 0.02 cc / (m²·day·bar) was spin-coated onto the silver-plated surface of the wafer. Thermal slip debonding was used to separate the wafer from the carrier. The UV film was then exposed to ultraviolet light at a wavelength of 365 nm for curing, causing it to lose its adhesion to the silver-plated surface and be directly peeled off.

[0055] In the above embodiments, when the high-temperature resistant film is made of a high-temperature resistant UV film, the high-temperature resistant UV film is cured under exposure to 365nm wavelength ultraviolet light (UV light) to form a cross-linked 3D network structure. This results in the loss or weakening of adhesion between the film and the silver-plated surface, thus achieving separation of the high-temperature resistant UV film from the silver-plated surface. This separation can be achieved manually or by using equipment to peel the film off. Compared to the high-temperature resistant film types in the aforementioned embodiments, the high-temperature resistant UV film further simplifies the process and improves production efficiency.

[0056] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for debonding bonded sheets, characterized in that, The bonding sheet includes a wafer, the wafer including a silver-plated surface and a device surface disposed opposite to each other; The carrier is bonded to the device surface via a bonding dielectric layer; The method for unbonding the bonded sheet includes the following steps: A high-temperature resistant film is applied to the silver-plated surface; Thermal glide debonding separates the wafer from the carrier; Remove the high-temperature resistant film.

2. The method as described in claim 1, characterized in that, The heat resistance temperature of the high-temperature resistant film is above 220℃; And / or, the elongation at break of the high-temperature resistant film is less than 5%; And / or, the thickness of the high-temperature resistant film is 20μm~100μm; And / or, the tensile strength of the high-temperature resistant membrane is 100MPa~150MPa; And / or, the oxygen permeability of the high-temperature resistant membrane is 0.01 cc / (m 2 ·day·bar)~0.5cc / (m 2 ·day·bar).

3. The method as described in claim 2, characterized in that, The high-temperature resistant film includes either a homopolymer polyimide film or a cyclopolymer polyimide film. And / or, the method of applying a high-temperature resistant film to the silver-plated surface includes bonding with an adhesive.

4. The method as described in claim 3, characterized in that, The methods for removing the high-temperature resistant membrane include: A protective film is applied to the device side of the wafer; the high-temperature resistant film on the silver-plated surface is fixed, the wafer is moved to separate from the high-temperature resistant film, the high-temperature resistant film is removed, and the adhesive is cleaned; the protective film is then removed.

5. The method as described in claim 3, characterized in that, The viscosity of the adhesive is 500 mPa·s to 10000 mPa·s; And / or, the adhesive comprises any one of a one-component acrylate adhesive, an epoxy resin adhesive, or a silicone-based adhesive.

6. The method as described in claim 4, characterized in that, The solvent used to clean the adhesive includes any one or a combination of at least two of isopropanol, acetone, or ethanol.

7. The method as described in claim 4, characterized in that, The method of cleaning the adhesive includes ultrasonic cleaning.

8. The method as described in claim 6, characterized in that, The protective film includes any one of a UV film, a polyethylene terephthalate film, a polyethylene film, or a polyimide film.

9. The method as described in claim 2, characterized in that, The material of the high-temperature resistant film includes a high-temperature UV resistant film.

10. The method as described in claim 9, characterized in that, One method for applying a high-temperature resistant UV film to the silver-plated surface is spin coating.

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