Bonding layer of carrier wafer, preparation method of bonding layer, wafer bonding structure and photon de-bonding method

Abstract

The invention provides a bonding layer of a carrier wafer, a preparation method of the bonding layer, a wafer bonding structure and a photon de-bonding method. The bonding layer comprises an inorganic medium layer and an inorganic heat conduction layer which are arranged on the surface of the transparent carrier in a stacked mode in the direction away from the surface of the transparent carrier. According to the invention, the laminated structure of the inorganic dielectric layer and the inorganic heat conduction layer is arranged on the surface of the transparent carrier, so that the wide spectrum absorption capability of the bonding layer is enhanced under the condition that the surface has relatively low roughness; the solar cell has the advantages of being high in photo-thermal conversion efficiency, extremely low in transmittance, high in high temperature resistance and chemical resistance and repeatable.

Description

Technical Field

[0001] The present invention belongs to the technical field of advanced electronic packaging, and relates to a bonding layer of a carrier wafer and a preparation method thereof, a wafer bonding structure, and a photon debonding method. Background Art

[0002] As the requirements for the integration and functionality of various semiconductor devices become increasingly higher, the direction of research has gradually shifted to achieving high-density, thin packaging. 2.5D integration, 3D integration, and fan-out wafer-level packaging based on TSV technology expand the package area to accommodate more input / output pins (I / O), while achieving a thinner and flatter package morphology, and can produce electronic components with good electrical characteristics at a lower cost. Among them, the carrying and holding of ultra-thin wafers requires first bonding the device wafer to the carrier wafer, and the carrier wafer provides mechanical support for the functional wafer; then the device wafer is rewired or reconstructed, and after completion, the device wafer is separated from the bonded carrier by debonding. This process is called temporary bonding and debonding technology.

[0003] There are several methods for separating a thinned wafer from its temporary carrier wafer, also known as debonding. With emerging technologies requiring ultra-thin device wafers, traditional debonding processes can present key challenges, such as minimizing damage to the ultra-thin wafer. Because each method has a different debonding mechanism, the application, the material properties of the thinned wafer, and downstream processing must be considered.

[0004] Common debonding methods include thermal slip, mechanical debonding, chemical debonding, laser debonding, and photon debonding. Thermal slip and mechanical methods inevitably generate significant mechanical stress during the ultra-thin wafer peeling process, resulting in a high breakage rate. The principles of thermal slip and chemical dissolution conflict with the requirements for high-temperature and chemical resistance. Furthermore, laser debonding processes present issues such as expensive equipment, unsuitability for warped wafers, and high carbon debris at the separation interface. Photon debonding utilizes a pulsed broadband light source to irradiate the inorganic release layer, generating transient high temperatures and thereby debonding the wafer bond pair. Photon debonding relies on a flash lamp generating high-intensity pulsed light in a short period of time. The transient high temperatures generated by the photothermal conversion effect promote interfacial debonding of the bonding material. However, current inorganic release materials have a reflectivity of over 40% across a wide spectrum (200-1200nm). This results in low photothermal conversion efficiency and significant safety risks from the reflected high-energy pulsed light.

[0005] Therefore, how to solve the above-mentioned problem of photon debonding law is urgently needed to be explored. Summary of the Invention

[0006] In response to the shortcomings of the prior art, the present invention aims to provide a carrier wafer bonding layer, a method for preparing the same, a wafer bonding structure, and a photon debonding method. The present invention provides a laminated structure of an inorganic dielectric layer and an inorganic thermal conductive layer on the surface of a transparent carrier wafer. This enhances the broad spectrum absorption capability of the bonding layer while maintaining a low surface roughness. When used in the photon debonding process of a wafer, the method exhibits high photothermal conversion efficiency, extremely low transmittance, strong high-temperature and chemical resistance, and repeatability.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a bonding layer of a carrier wafer for photon debonding, wherein the bonding layer includes an inorganic dielectric layer and an inorganic thermal conductive layer stacked on the surface of the transparent carrier in a direction away from the surface of the transparent carrier.

[0009] It should be noted that the bonding layer in the present invention is merely a stacking structure on the surface of the carrier wafer, which can be bonded to the surface of the second wafer to form a wafer bonding structure.

[0010] The present invention sets a bonding layer of a laminated structure including an inorganic dielectric layer and an inorganic thermal conductive layer on the surface of a transparent carrier. The stacking order and the coating type in the laminated structure cooperate with each other. The inorganic dielectric layer has a strong resonant interference effect, which improves the absorption performance of wide-band light. The inorganic thermal conductive layer plays a protective role and also has excellent thermal performance. The bonding layer has excellent high-temperature resistance, light-to-heat conversion efficiency, low transmittance and reusability under low surface roughness. When used in the photon debonding process under a wide spectral range (especially in the temporary debonding process with the device wafer), it has high wide-spectrum absorption performance and low debonding threshold. After debonding, the bonding layer and the transparent carrier are still intactly bonded, and the debonding effect is excellent, which facilitates the reuse of the transparent carrier wafer with the bonding layer and reduces the cost of the photon debonding process.

[0011] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0012] Preferably, the inorganic dielectric layer includes a first inorganic material, and the band gap of the first inorganic material is 3 to 6 eV, for example, 3eV, 3.5eV, 4eV, 4.5eV, 5eV, 5.5eV or 6eV, etc., but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0013] In the present invention, the first inorganic material with a band gap of 3 to 6 eV is selected as the material of the inorganic dielectric layer, which is more conducive to improving the reflectivity of photons and increasing the interaction time between light and matter, thereby enhancing the interference effect.

[0014] Preferably, the first inorganic material has a temperature tolerance of ≥700°C, for example, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C, 1100°C, 1150°C, 1200°C, 1300°C, 1400°C or 1500°C, etc., but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0015] Preferably, the thermal expansion coefficient of the first inorganic material is 3×10 -6 ~1×10 -5 / ℃, for example 3×10 -6 / ℃、4×10 -6 / ℃、5×10 -6 / ℃、6×10 -6 / ℃、7×10 -6 / ℃、8×10 -6 / ℃、9×10 -6 / ℃ or 1×10 -5 / ℃, etc., but are not limited to the listed values. Other values not listed within the numerical range are also applicable;

[0016] Preferably, the first inorganic material includes SiC, BN, Si3N4, AlN, ZnO, TiO x , any one of ZrO2, Ta2O5, Cr2O3, In2Se3, Si or Ge, or a combination of at least two of them.

[0017] In the present invention, the first inorganic material is selected from the above substances, which further improves the light absorption rate in the wide wavelength range of 200 to 1200 nm and improves the light-to-heat conversion efficiency.

[0018] Preferably, the inorganic heat-conducting layer comprises a second inorganic material, and the thermal expansion coefficient of the second inorganic material is 3×10 -6 ~1×10 -5 / ℃, for example 3×10 -6 / ℃、4×10 -6 / ℃、5×10 -6 / ℃、6×10 -6 / ℃、7×10 -6 / ℃、8×10 -6 / ℃、9×10 -6 / ℃ or 1×10 -5 / ℃, etc., but are not limited to the listed values. Other values not listed within the numerical range are also applicable.

[0019] In the present invention, the thermal expansion coefficient of the first inorganic material and / or the second inorganic material is preferably independently 3×10 -6 ~1×10 -5 / ℃, which can make the thermal expansion coefficient between the transparent carrier wafer and the bonding layer have a good match, which is beneficial to reduce the damage caused by thermal mismatch during the photon debonding process.

[0020] Preferably, the temperature resistance of the second inorganic material is ≥700°C, for example 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C, 1100°C, 1150°C, 1200°C, 1300°C, 1400°C or 1500°C, etc., but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0021] The first inorganic material and / or the second inorganic material of the present invention preferably have a temperature tolerance of ≥700° C. independently, which can achieve excellent photon debonding effect without affecting the subsequent high-temperature process of the wafer after debonding.

[0022] Preferably, the second inorganic material is selected from opaque materials.

[0023] In the present invention, the second inorganic material is ensured to be in an opaque state, thereby preventing the pulse light from directly irradiating the device wafer during the photon debonding process, thereby preventing the wafer from being damaged.

[0024] Preferably, the second inorganic material includes any one of a non-metallic material, a metallic material, or an alloy material, or a combination of at least two of them.

[0025] Preferably, the non-metallic material includes a carbon material.

[0026] Preferably, the metal material includes any one of W, Ta, Mo, Cr, Zr or Ti, or a combination of at least two of them.

[0027] Preferably, the alloy material includes any one of Ti alloy, W alloy, Mo alloy or Ni alloy, or a combination of at least two of them.

[0028] It should be noted that when the alloy material provided by the present invention includes the first element and the second element, the mass ratio of the two elements can be combined in any proportion under the premise of meeting the requirements of the present invention.

[0029] For example, the titanium alloy includes any one of TiC, TiN or TiW or a combination of at least two of them. It is further preferred that the mass ratio of titanium element to alloy combination elements is between 1:10 and 10:1, such as 1:9, 2:8, 3:7, 5:1 or 10:1.

[0030] For example, the W alloy includes WC, etc. Preferably, the mass ratio of W element to carbon element is between 1:10 and 10:1, such as 1:10, 1:5, 1:1, 5:1 or 10:1.

[0031] In the present invention, the specific material selection of the first inorganic material and the specific material selection of the second inorganic material cooperate with each other to jointly improve the adhesion of the materials on the surface of the transparent carrier.

[0032] Preferably, the total thickness of the bonding layer is 0.15 to 5 μm, for example, 0.15 μm, 0.2 μm, 0.5 μm, 0.8 μm, 1 μm, 1.3 μm, 1.5 μm, 1.8 μm, 2 μm, 2.3 μm, 2.5 μm, 2.8 μm, 3 μm, 3.3 μm, 3.5 μm, 3.8 μm, 4 μm, 4.3 μm, 4.5 μm, 4.8 μm or 5 μm, etc., but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0033] In the present invention, the thickness of the bonding layer is regulated to be 0.15 to 5 μm, which is more conducive to forming an ultra-thin bonding film layer, reducing the heat conduction path, and reducing the preparation time and cost.

[0034] Preferably, the thickness of the inorganic dielectric layer is 20 to 100 nm, for example, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm, but is not limited to the listed values. Other values not listed within the numerical range are also applicable.

[0035] In the present invention, the thickness of the inorganic dielectric layer is preferably smaller than that of the inorganic heat conductive layer, which is more conducive to heat conduction. Furthermore, the thickness of the inorganic dielectric layer is preferably 20-100 nm, which enhances the interference effect.

[0036] Preferably, the thickness of the inorganic thermal conductive layer is 0.1 to 5 μm, for example, 0.1 μm, 0.15 μm, 0.2 μm, 0.5 μm, 0.8 μm, 1 μm, 1.3 μm, 1.5 μm, 1.8 μm, 2 μm, 2.3 μm, 2.5 μm, 2.8 μm, 3 μm, 3.3 μm, 3.5 μm, 3.8 μm, 4 μm, 4.3 μm, 4.5 μm, 4.8 μm or 5 μm, etc., but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0037] In the present invention, the thickness of the inorganic heat-conducting layer is adjusted to be 0.1 to 5 μm, which further reduces the transmittance and prevents the device layer from being damaged by light.

[0038] Preferably, the roughness of the surface of the inorganic thermal conductive layer away from the side of the transparent carrier wafer is ≤50nm, for example, 0nm, 5nm, 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm or 50nm, etc., but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0039] In the present invention, the surface roughness of the inorganic thermal conductive layer is regulated to be ≤50nm, that is, the surface roughness of the bonding layer is ≤50nm, which ensures the smooth surface of the bonding layer. It is further proved that even when the surface roughness of the bonding layer is low, the present invention can still have excellent high temperature resistance, light-to-heat conversion efficiency, low transmittance and reusability under the synergistic effect of the laminated structure.

[0040] Preferably, the absorbance of the bonding layer within a preset spectral range is ≥50%, for example, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 100%, etc., but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0041] Preferably, the transmittance of the bonding layer in a preset spectral range is ≤0.1%.

[0042] In the present invention, the bonding layer has a high absorbance in a wide spectral range and an extremely low transmittance, which can better play its role in the photon debonding process; and considering that the spectral range of the pulsed light used in the photon debonding process of this application is preferably 200~1200nm, it is further preferred that the preset spectral range is selected from 200~1200nm.

[0043] In a second aspect, the present invention provides a method for preparing a bonding layer of a carrier wafer for photon debonding as described in the first aspect, the preparation method comprising:

[0044] An inorganic dielectric layer is arranged on at least one side surface of the transparent carrier, and then an inorganic heat conductive layer is arranged on the surface of the inorganic dielectric layer to obtain a bonding layer of the carrier wafer for photon debonding.

[0045] The preparation method provided by the present invention is simple to operate and can obtain the corresponding bonding layer without complicated processing procedures.

[0046] It should be noted that the present invention does not limit the specific preparation method of the inorganic dielectric layer and the inorganic thermal conductive layer. The present invention is applicable to any method that can achieve the corresponding purpose and is reasonably known to those skilled in the art.

[0047] For example, the inorganic dielectric layer and the inorganic thermal conductive layer can be deposited by a deposition method, or can be obtained by a magnetron sputtering method, a pulsed laser deposition method, a spraying method, or the like.

[0048] In a third aspect, the present invention provides a wafer bonding structure, comprising a first wafer, a second wafer, and a bonding structure between the first wafer and the second wafer;

[0049] The first wafer comprises a transparent carrier having a bonding layer as described in the first aspect, and the second wafer comprises a device wafer having an organic bonding layer on a surface to be bonded;

[0050] The bonding layer and the organic adhesive layer are bonded to each other to form the bonding structure.

[0051] The wafer bonding structure provided by the present invention is bonded to each other by the bonding layer of the transparent carrier provided by the first aspect and the organic bonding layer on the surface of the device wafer, which can not only ensure the bonding effect between the transparent carrier wafer and the device wafer, but also will not cause any damage to the device wafer during the photon debonding process.

[0052] Preferably, the bonding strength after bonding between the bonding surface and the organic bonding layer is 0.1 to 5 N / 30 mm, for example, 0.1 N / 30 mm, 0.5 N / 30 mm, 1 N / 30 mm, 1.5 N / 30 mm, 2.5 N / 30 mm, 3 N / 30 mm, 3.5 N / 30 mm, 4 N / 30 mm, 4.5 N / 30 mm or 5 N / 30 mm, etc., but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0053] Preferably, the thickness of the organic bonding layer is 2 to 200 μm, for example, 2 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm or 200 μm, etc., but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0054] In the present invention, the thickness of the organic bonding layer is relatively thick, preferably 2 to 200 μm, which is more conducive to preventing the device wafer from being thermally damaged and covering the micro-bumps of the device layer.

[0055] Preferably, the 5% thermal decomposition temperature of the organic bonding material in the organic bonding layer is ≥300°C, for example, 300°C, 325°C, 350°C, 375°C, 400°C, 425°C, 450°C, 475°C or 500°C, etc., but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0056] It is understood that the thermal decomposition of 5% (T d , 5%) refers to the temperature at which the material loses 5% of its weight during thermal decomposition, usually determined by thermogravimetric analysis (TGA); this temperature is preferably ≥300°C, which can better meet the subsequent high-temperature process technology.

[0057] Furthermore, the present invention does not impose any special limitations on the organic bonding material in the organic bonding layer. For example, the organic bonding agent can be selected from at least one of WLP PB901, PB902, PB903, PB904, PB906 or PB916 of Shenzhen Huaxun Semiconductor Materials Co., Ltd.; in addition, the composite method between the organic bonding layer and the device wafer is also a conventional technical solution. Those skilled in the art can make adaptive selections and adjustments based on actual needs, such as spin-coating the organic bonding material on the surface of the device wafer and then pre-curing it to obtain an organic bonding layer.

[0058] It should also be noted that the bonding method of the wafer bonding structure in the present invention is also a conventional technical solution, and the present invention is applicable to all methods that can be known within a reasonable range by those skilled in the art.

[0059] Exemplarily, the present invention provides a bonding method:

[0060] The bonding surface of the first wafer and the organic bonding layer of the second wafer are bonded to each other, and then vacuum hot-pressed to obtain a wafer bonding structure.

[0061] The bonding surface of the first wafer and the organic bonding layer of the second wafer are bonded to each other, and then light-cured to obtain a wafer bonding structure.

[0062] Optionally, the power of the photocuring is 300-600 mW, such as 300 mW, 350 mW, 400 mW, 450 mW, 500 mW, 550 mW or 600 mW, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

[0063] Optionally, the photocuring time is 60 to 180 s, for example, 60 s, 70 s, 80 s, 90 s, 100 s, 110 s, 120 s, 130 s, 140 s, 150 s, 160 s, 170 s or 180 s, etc., but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0064] In a fourth aspect, the present invention further provides a photon debonding method, which is used for debonding the wafer bonding structure according to the third aspect, and the photon debonding method comprises:

[0065] Pulsed light is used to irradiate the first wafer in the wafer bonding structure to complete debonding of the first wafer and the second wafer.

[0066] Preferably, the second wafer in the wafer bonding structure is first thinned, and then the first wafer in the wafer bonding structure is irradiated with pulsed light.

[0067] In the present invention, when a wafer bonding structure containing the bonding layer of the first aspect is used to perform debonding (especially temporary debonding) of a device wafer and a transparent carrier, a broad spectrum light beam emitted by a pulsed light passes through the transparent carrier and irradiates the laminated structure of the bonding layer by a photon debonding method. Under the synergistic effect of the inorganic dielectric layer and the inorganic thermal conductive layer, the bonding layer has a very high photothermal conversion efficiency, and the debonding threshold between the bonding layer and the organic bonding layer is low. The photothermal conversion effect generates an instantaneous high temperature, which promotes thermal decomposition or thermal mismatch at the interface between the inorganic thermal conductive layer and the organic bonding layer in the bonding layer, so that the bonded wafer is at the interface between the inorganic thermal conductive layer and the organic bonding layer. Stress-free separation occurs at the interface, realizing debonding of the wafer bonded pair. After photon debonding, almost no carbonized debris appears on the surface of both the transparent carrier wafer and the device wafer. In addition, the bonding layer remains intact on the transparent carrier wafer and can be reused after cleaning. At the same time, no obvious residue of the bonding layer material is observed on the organic bonding layer. The organic bonding layer on its surface can be easily removed, and the surface of the device wafer is not damaged. The laminated structure of the bonding layer can be reused, reducing the cost of the photon debonding process. The photon debonding method provided by the present invention also has the advantages of simple operation, good universality and good compatibility with semiconductor processes.

[0068] In addition, the bonding layer provided by the first aspect of the present invention is difficult to be applied to other debonding methods. If laser debonding is used, the problem of the photon release layer falling off may occur.

[0069] Preferably, the thickness of the second wafer in the wafer bonding structure after thinning is ≤100μm, for example, 100μm, 95μm, 90μm, 85μm, 80μm, 75μm, 70μm, 65μm, 60μm, 55μm, 50μm, 40μm, 30μm, 20μm or 10μm, etc., but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0070] The bonding layer of the first aspect provided by the present invention is also suitable for the thinning process of the device wafer. The bonding layer in the transparent carrier and the organic bonding layer in the device wafer have high bonding strength and excellent bonding effect, which can realize the thinning of the device wafer first and then debonding without causing damage to the device wafer or destruction of the bonding structure.

[0071] In the present invention, an ultra-thin device wafer structure can be obtained, thereby broadening the application range of the wafer.

[0072] Preferably, the spectrum range of the pulsed light is 200 to 1200 nm.

[0073] Preferably, the pulse duration of the pulse light is 50 to 5000 μs, for example, 50 μs, 100 μs, 500 μs, 1000 μs, 1500 μs, 2000 μs, 2500 μs, 3000 μs, 3500 μs, 4000 μs, 4500 μs or 5000 μs, etc., preferably 100 to 300 μs, but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0074] In the debonding process of the present invention, the pulse duration is short, and instantaneous high temperature can be achieved, thereby achieving the purpose of rapid debonding.

[0075] Preferably, the energy density of the pulsed light irradiated in the inorganic release material layer is ≤20 J / cm 2 , for example 1J / cm 2 , 2J / cm 2 , 3J / cm 2 , 4J / cm 2 , 5J / cm 2 , 6J / cm 2 , 7J / cm 2 , 8J / cm 2 , 9J / cm 2 , 10J / cm 2 , 11J / cm 2 , 12J / cm 2 , 13J / cm 2 , 14J / cm 2 , 15J / cm 2 , 16J / cm 2 , 17J / cm 2 , 18J / cm 2 , 19J / cm 2 or 20J / cm 2 etc., preferably 2 to 20 J / cm 2 , but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0076] Preferably, the spot overlap rate of the pulsed light is ≤5%, for example 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%, etc., but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0077] It should also be noted that after irradiation, a transparent carrier having the bonding layer described in the first aspect and a device wafer having the organic bonding layer described in the third aspect are obtained respectively; the two can be stress-free separated by a suction cup; after further cleaning the transparent carrier and the device wafer, a reusable transparent carrier having the bonding layer described in the first aspect and a device wafer with the organic bonding layer removed are obtained respectively.

[0078] Compared with the prior art, the present invention has the following beneficial effects:

[0079] (1) The present invention sets a bonding layer of a laminated structure including an inorganic dielectric layer and an inorganic thermal conductive layer on the surface of a transparent carrier. The stacking order and the coating type in the laminated structure cooperate with each other. The interference effect of the inorganic dielectric layer is high, which enhances the light absorption performance. The inorganic thermal conductive layer plays a protective role and also has excellent thermal performance. As a result, the bonding layer still has excellent high temperature resistance, light-to-heat conversion efficiency, low transmittance and reusability under low surface roughness. When used in the photon debonding process under a wide spectral range (especially in the temporary debonding process with the device wafer), it has high wide-spectrum absorption performance and a high debonding threshold. After debonding, the bonding layer and the transparent carrier wafer are still intactly bonded, and the debonding effect is excellent, which facilitates the reuse of the transparent carrier with the bonding layer and reduces the cost of the photon debonding process.

[0080] (2) The wafer bonding structure provided by the present invention is characterized by bonding the bonding layer of the transparent carrier wafer provided by the first aspect to the organic bonding layer on the surface of the device wafer, which can ensure the bonding effect between the transparent carrier wafer and the device wafer and will not cause any damage to the device wafer during the photon debonding process.

[0081] (3) In the present invention, when the wafer bonding structure containing the bonding layer of the first aspect is used to perform debonding (especially temporary debonding) of the device wafer and the transparent carrier, a wide spectrum beam emitted by pulsed light passes through the transparent carrier wafer and irradiates the laminated structure of the bonding layer through the photon debonding method. Under the synergistic effect of the inorganic dielectric layer and the inorganic thermal conductive layer, the bonding layer has a very high photothermal conversion efficiency, and the debonding threshold between the bonding layer and the organic bonding layer is at a level where an instantaneous high temperature is generated through the photothermal conversion effect, which promotes thermal decomposition or thermal mismatch at the interface between the inorganic thermal conductive layer and the organic bonding layer in the bonding layer, so that the bonded wafer is at a high temperature at the interface between the inorganic thermal conductive layer and the organic bonding layer. Stress-free separation occurs at the interface of the bonding layer, achieving debonding of the wafer bonded pair. After photon debonding, almost no carbonized debris appears on the surfaces of the transparent carrier wafer and the device wafer. In addition, the bonding layer remains intact on the transparent carrier wafer and can be reused after cleaning. At the same time, no obvious residue of inorganic release material is observed on the organic bonding layer. The organic bonding layer on its surface can be easily removed, and the surface of the device wafer is not damaged. The photon release material can be reused, reducing the cost of the photon debonding process. The photon debonding method provided by the present invention also has the advantages of simple operation, good universality, and good compatibility with semiconductor processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] Figure 1 This is a flow chart of the method for all processes in Example 1, including preparation of the bonding layer, bonding of the wafer bonding structure, and completion of debonding of the transparent carrier wafer and the device wafer.

[0083] Figure 2 3 is a comparison chart of the reflectivity of the bonding layer in Example 1 and the bonding layer in Comparative Example 1 within the wavelength range of 200 to 1200 nm.

[0084] Figure 3 3 is a comparison chart of the transmittance of the bonding layer in Example 1 and the bonding layer in Comparative Example 1 within the wavelength range of 200 to 1200 nm.

[0085] Figure 4 A sample diagram of the wafer bonding structure provided in Example 1.

[0086] Figure 5 Surface images of the organic bonding layer of the device wafer and the bonding layer in the transparent carrier wafer after separation in step S6 in Example 1.

[0087] Figure 6 Surface images of the device wafer after cleaning in step S7 in Example 1 and the bonding layer in the transparent carrier wafer.

[0088] Among them, 1-transparent carrier wafer, 2-inorganic dielectric layer, 3-inorganic thermal conductive layer, 4-device wafer, 5-organic bonding layer, 6-wafer bonding structure, 7-ultra-thin wafer bonding structure, 8-pulse flash lamp, 9-light beam, 10-cleaning agent for cleaning ultra-thin device wafers, 11-single ultra-thin chip structure. DETAILED DESCRIPTION

[0089] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0090] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in this application are intended to cover non-exclusive inclusions.

[0091] In the description of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly indicate the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0092] Example 1

[0093] This embodiment provides a bonding layer of a carrier wafer for photon debonding, a wafer bonding structure including the bonding layer, and a method for photon debonding of the wafer bonding structure.

[0094] Bonding layer of the carrier wafer: Along the direction away from the surface of the transparent carrier wafer, the bonding layer includes an inorganic dielectric layer Si3N4 layer (the first inorganic material is Si3N4) and an inorganic thermal conductive layer TiW layer (the second inorganic material is TiW) stacked on the surface of the transparent carrier wafer.

[0095] Wafer bonding structure: the wafer bonding structure includes a first wafer, a second wafer, and a bonding structure between the first wafer and the second wafer;

[0096] The first wafer is a transparent carrier wafer having the bonding layer as described above, and the second wafer is a device wafer having an organic bonding layer on the surface to be bonded; the bonding layer and the organic bonding layer are bonded to each other to form the bonding structure.

[0097] like Figure 1As shown, this embodiment also provides a method for completing all processes from preparation of a bonding layer, bonding of a wafer bonding structure, and debonding of a transparent carrier wafer and a device wafer:

[0098] S1: On a transparent carrier wafer 1 (Schott glass, 8 inches, 700 μm), a 50 nm thick inorganic dielectric layer 2 (Si3N4 thin film) and a 200 nm thick inorganic thermal conductive layer 3 (TiW thin film) are sequentially deposited. The surface roughness of the inorganic thermal conductive layer 3 is 15 nm, thereby obtaining a bonding layer on the surface of the transparent carrier wafer 1.

[0099] S2: An organic bonding material (purchased from Shenzhen Huaxun Semiconductor Materials Co., Ltd., WLP PB902) was spin-coated onto a device wafer 4 (silicon wafer, 8 inches, 500 μm) using the following spin-coating parameters: 1100 rpm for 30 seconds, then 3000 rpm for another 2 seconds. The material was then pre-cured by heating at 110° C. for 5 minutes, then at 220° C. for 10 minutes, and then spun off. The resulting organic bonding layer 5 had a thickness of 35 μm and an absorbance of less than 5% at 355 nm.

[0100] S3: If Figure 4 As shown, a transparent carrier wafer 1 having a bonding layer and a device wafer 4 having an organic bonding layer 5 are bonded to form a wafer bonding structure 6 by vacuum hot-press bonding. The temperature during hot-press bonding is 200° C., the pressure is 5 kN, and the holding time is 10 min. In the wafer bonding structure obtained in this step, the bonding strength between the bonding layer and the organic bonding layer is 0.5 N / 30 mm as tested by a tensile testing machine.

[0101] S4: thinning the device wafer 4 to 100 μm by wafer backside thinning technology to obtain an ultra-thin wafer bonding structure 7;

[0102] S5: The energy density is 3.5 J / cm2 by pulse flash lamp 8 (spectral range is 200~1200 nm). 2 The light beam 9 passes through the transparent carrier wafer 1 to irradiate the bonding layer 3 with a spot overlap rate of 5%, and the pulse duration is 300 μs, thereby achieving debonding at the interface between the bonding layer in the transparent carrier wafer 1 and the organic adhesive layer 5;

[0103] S6: Lifting the transparent carrier wafer 1 by the suction cup, thereby achieving stress-free separation of the wafer bonding structure;

[0104] S7: Cleaning the transparent carrier wafer and the ultra-thin device wafer having the bonding layer of step (1) with a cleaning agent to obtain a cleaned ultra-thin device wafer (cleaning agent 10 for cleaning the ultra-thin device wafer) and a reusable transparent carrier wafer;

[0105] S8: Slicing the cleaned ultra-thin device wafer to obtain a single ultra-thin chip structure 11.

[0106] Example 2

[0107] This embodiment provides a bonding layer of a carrier wafer for photon debonding, a wafer bonding structure including the bonding layer, and a method for photon debonding of the wafer bonding structure.

[0108] The bonding layer of the carrier wafer: in the direction away from the surface of the transparent carrier wafer, the bonding layer includes an inorganic dielectric layer Si3N4 layer and an inorganic thermal conductive layer TiW layer stacked on the surface of the transparent carrier wafer.

[0109] Wafer bonding structure: the wafer bonding structure includes a first wafer, a second wafer, and a bonding structure between the first wafer and the second wafer;

[0110] The first wafer is a transparent carrier wafer having the bonding layer as described above, and the second wafer is a device wafer having an organic bonding layer on the surface to be bonded; the bonding layer and the organic bonding layer are bonded to each other to form the bonding structure.

[0111] This embodiment also provides a method for completing all processes from preparation of a bonding layer, bonding of a wafer bonding structure, and debonding of a transparent carrier wafer and a device wafer:

[0112] S1: On a transparent carrier wafer (8 inches, 700 μm), a 20 nm thick inorganic dielectric layer (Si3N4 thin film) and a 1500 nm thick inorganic thermal conductive layer (TiW thin film) are sequentially deposited. The surface roughness of the inorganic thermal conductive layer is 50 nm to obtain a bonding layer on the surface of the transparent carrier wafer.

[0113] S2: An organic bonding material (purchased from Shenzhen Huaxun Semiconductor Materials Co., Ltd., WLP PB903) was spin-coated onto a device wafer (8-inch, 500 μm) using the following spin-coating parameters: 1100 rpm for 30 seconds, then 3000 rpm for another 2 seconds. The material was then pre-cured by heating at 110°C for 5 minutes, then at 220°C for 10 minutes, and then spun off. The resulting organic bonding layer had a thickness of 5 μm and exhibited an absorbance of less than 5% at 355 nm.

[0114] S3: Forming a wafer bonding structure by vacuum hot-press bonding of the transparent carrier wafer 1 having a bonding layer and the device wafer having an organic bonding layer. The temperature during hot-press bonding is 200° C., the pressure is 5 kN, and the holding time is 10 minutes. In the wafer bonding structure obtained in this step, the bonding strength between the bonding layer and the organic bonding layer is 1 N / 30 mm as tested by a tensile testing machine.

[0115] S4: Thinning the device wafer to 80μm using wafer backside thinning technology to obtain an ultra-thin wafer bonding structure;

[0116] S5: A pulsed flash lamp (spectral range 200-1200 nm) was used to generate an energy density of 6 J / cm 2 The light beam 9 passes through the transparent carrier wafer to irradiate the bonding layer with a spot overlap rate of 3%, and the pulse duration is 200 μs, thereby achieving debonding at the interface between the bonding layer in the transparent carrier wafer and the organic adhesive layer 5;

[0117] S6: Lifting the transparent carrier wafer by the suction cup to achieve stress-free separation of the wafer bonding structure;

[0118] S7: Cleaning the transparent carrier wafer and the ultra-thin device wafer having the bonding layer of step (1) with a cleaning agent to obtain a cleaned ultra-thin device wafer and a reusable transparent carrier wafer;

[0119] S8: Slicing the cleaned ultra-thin device wafer to obtain a single ultra-thin chip structure.

[0120] Example 3

[0121] This embodiment provides a bonding layer of a carrier wafer for photon debonding, a wafer bonding structure including the bonding layer, and a method for photon debonding of the wafer bonding structure.

[0122] The bonding layer of the carrier wafer: in the direction away from the surface of the transparent carrier wafer, the bonding layer includes an inorganic dielectric layer Si3N4 layer and an inorganic thermal conductive layer TiW layer stacked on the surface of the transparent carrier wafer.

[0123] Wafer bonding structure: the wafer bonding structure includes a first wafer, a second wafer, and a bonding structure between the first wafer and the second wafer;

[0124] The first wafer is a transparent carrier wafer having the bonding layer as described above, and the second wafer is a device wafer having an organic bonding layer on the surface to be bonded; the bonding layer and the organic bonding layer are bonded to each other to form the bonding structure.

[0125] This embodiment also provides a method for completing all processes from preparation of a bonding layer, bonding of a wafer bonding structure, and debonding of a transparent carrier wafer and a device wafer:

[0126] S1: On a transparent carrier wafer (8 inches, 700 μm), a 100 nm thick inorganic dielectric layer (Si3N4 thin film) and a 4.5 μm thick inorganic thermal conductive layer (TiW thin film) are sequentially deposited. The surface roughness of the inorganic thermal conductive layer is 15 nm to obtain a bonding layer on the surface of the transparent carrier wafer.

[0127] S2: An organic bonding material (purchased from Shenzhen Huaxun Semiconductor Materials Co., Ltd., WLP PB902) was spin-coated onto a device wafer (8-inch, 500 μm) using the following spin-coating parameters: 1100 rpm for 30 seconds, then 3000 rpm for another 2 seconds. The material was then pre-cured by heating at 110°C for 5 minutes, then at 220°C for 10 minutes, and then spun off. The resulting organic bonding layer had a thickness of 200 μm and exhibited an absorbance of less than 5% at 355 nm.

[0128] S3: A transparent carrier wafer 1 having a bonding layer and a device wafer 4 having an organic bonding layer are bonded to form a wafer bonding structure by vacuum hot-press bonding. The temperature during hot-press bonding is 180° C., the pressure is 5 kN, and the holding time is 15 minutes. In the wafer bonding structure obtained in this step, the bonding strength between the bonding layer and the organic bonding layer is 5 N / 30 mm as tested by a tensile testing machine.

[0129] S4: thinning the device wafer 4 to 100 μm by wafer backside thinning technology to obtain an ultra-thin wafer bonding structure 7;

[0130] S5: The energy density is 10 J / cm2 by pulse flash lamp 8 (spectral range is 200-1200 nm). 2 The light beam 9 passes through the transparent carrier wafer 1 to irradiate the bonding layer 3 with a spot overlap rate of 5%, and the pulse duration is 100 μs, thereby achieving debonding at the interface between the bonding layer and the organic adhesive layer in the transparent carrier wafer;

[0131] S6: Lifting the transparent carrier wafer 1 by the suction cup, thereby achieving stress-free separation of the wafer bonding structure;

[0132] S7: Cleaning the transparent carrier wafer and the ultra-thin device wafer having the bonding layer of step (1) with a cleaning agent to obtain a cleaned ultra-thin device wafer and a reusable transparent carrier wafer;

[0133] S8: Slicing the cleaned ultra-thin device wafer to obtain a single ultra-thin chip structure.

[0134] Example 4

[0135] The difference between this embodiment and embodiment 1 is that the inorganic dielectric layer in this embodiment is a ZrO2 layer, and the inorganic thermal conductive layer is a W layer.

[0136] In step S1 of the corresponding method, the adaptive adjustment is to sequentially deposit a 50 nm thick inorganic dielectric layer (ZrO2 thin film) and a 200 nm thick inorganic thermal conductive layer (W thin film) on a transparent carrier wafer 1 (8 inches, 700 μm).

[0137] The other conditions are the same as those in Example 1.

[0138] Example 5

[0139] The difference between this embodiment and embodiment 1 is that the inorganic dielectric layer in this embodiment is a silicon oxide layer (ie, the first inorganic material is silicon oxide).

[0140] In step S1 of the corresponding method, the adaptive adjustment is to sequentially deposit a 50 nm thick silicon oxide film on a transparent carrier wafer 1 (8 inches, 700 μm).

[0141] The other conditions are the same as those in Example 1.

[0142] Example 6

[0143] The difference between this embodiment and embodiment 1 is that the inorganic heat-conducting layer in this embodiment is an Al layer (ie, the second inorganic material is Al metal).

[0144] In step S1 of the corresponding method, the adaptive adjustment is to deposit an Al layer on the surface of the inorganic dielectric layer.

[0145] The other conditions are the same as those in Example 1.

[0146] Example 7

[0147] The difference between this embodiment and embodiment 1 is that the thickness of the inorganic dielectric layer in this embodiment is 250 nm.

[0148] The other conditions are the same as those in Example 1.

[0149] Example 8

[0150] The difference between this embodiment and embodiment 1 is that the thickness of the inorganic dielectric layer in this embodiment is 15 nm.

[0151] The other conditions are the same as those in Example 1.

[0152] Example 9

[0153] The difference between this embodiment and embodiment 1 is that the thickness of the inorganic heat conductive layer in this embodiment is 80 nm.

[0154] The other conditions are the same as those in Example 1.

[0155] Comparative Example 1

[0156] The difference between this comparative example and Example 1 is that the surface of the transparent carrier wafer in this comparative example does not contain an inorganic dielectric layer.

[0157] In step S1 of the method, an inorganic heat-conducting layer is directly deposited on the surface of the transparent carrier wafer.

[0158] The other conditions are the same as those in Example 1.

[0159] Comparative Example 2

[0160] The difference between this comparative example and Example 1 is that in this comparative example, the stacking order of the inorganic dielectric layer and the inorganic thermal conductive layer is adjusted.

[0161] In step S1 of the method, an inorganic heat-conducting layer (TiW film) with a thickness of 200 nm and an inorganic dielectric layer (Si3N4 film) with a thickness of 50 nm are sequentially deposited on a transparent carrier wafer 1 (8 inches, 700 μm).

[0162] The other conditions are the same as those in Example 1.

[0163] Table 1 shows the band gap value, thermal expansion coefficient and temperature tolerance of the first inorganic material in the inorganic dielectric layer provided in Examples 1-9 and Comparative Examples 1-2, the thermal expansion coefficient and temperature tolerance of the second inorganic material in the inorganic thermal conductive layer, the photothermal conversion efficiency of the bonding layer, and the reflectivity, absorbance and transmittance of the bonding layer in the spectral range of 200 to 1200 nm.

[0164] The reflectivity, absorbance, and transmittance were measured using a spectrometer (UV-Vis-NIR Spectrophotometer). The photothermal conversion efficiency was approximately calculated based on the absorbance.

[0165] Figure 2 The comparative diagram of the reflectivity of the bonding layer in Example 1 and the bonding layer in Comparative Example 1 in the wavelength range of 200 to 1200 nm is shown. Figure 2 It can be seen that the bonding layer with the specific stacked structure in Example 1 of the present invention can effectively reduce the reflectivity in the wavelength range of 200-1200 nm compared with the bonding layer without the inorganic dielectric layer in Comparative Example 1.

[0166] Figure 3 A comparison chart of the transmittance of the bonding layer in Example 1 and the bonding layer in Comparative Example 1 in the wavelength range of 200 to 1200 nm is shown. The bonding layer with the specific laminated structure in Example 1 of the present invention can effectively improve the transmittance in the wavelength range of 200-1200 nm compared with the bonding layer in Comparative Example 1 that does not contain an inorganic dielectric layer.

[0167] Table 1

[0168]

[0169]

[0170] Table 2 shows the debonding results of Examples 1-11 and Comparative Examples 1-2 during the photon debonding process.

[0171] Figure 4 A sample diagram of the wafer bonding structure provided in Example 1 is shown.

[0172] Figure 5 The surface image of the organic bonding layer of the device wafer after separation in step S6 in Example 1 and the surface image of the bonding layer in the transparent carrier wafer are shown.

[0173] Figure 6 The surface image of the device wafer after cleaning in step S7 in Example 1 and the surface image of the bonding layer in the transparent carrier wafer are shown.

[0174] from Figures 4 to 6 It can be seen that according to the photon debonding method provided in Example 1 of the present invention, under the action of the bonding layer of the specific stacked structure, no carbonized debris appears on the surface of the separated transparent carrier wafer and the device wafer; in addition, after photon debonding, no obvious residue of inorganic material in the bonding layer is observed on the organic bonding layer; after the separated wafers are cleaned, the transparent carrier wafer containing the bonding layer in the present invention remains intact after photon debonding and can be reused after cleaning; at the same time, the organic bonding material on the surface of the device wafer can be easily removed and the device surface is not damaged.

[0175] The debonding results are characterized as follows: the transparent carrier wafer is pulled vertically by a vacuum suction cup, and a value close to the gravity of the glass wafer is judged as stress-free separation, and a higher pulling force is judged as stress separation. After separation, the transparent carrier wafer and the device wafer are observed under a light microscope and no obvious cracks are found, which is judged to be undamaged.

[0176] Table 2

[0177]

[0178] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A bonding layer of a carrier wafer for photonic debonding, characterized in that Along the direction away from the surface of the transparent carrier, the bonding layer sequentially includes an inorganic medium layer and an inorganic heat-conducting layer stacked on the surface of the transparent carrier.

2. The bonding layer of a carrier wafer for photonic debonding according to claim 1, characterized in that: The inorganic dielectric layer includes a first inorganic material, and the band gap of the first inorganic material is 3 to 6 eV; Preferably, the first inorganic material has a temperature tolerance of ≥700°C; Preferably, the thermal expansion coefficient of the first inorganic material is 3×10 -6 ~1×10 -5 / ℃; Preferably, the first inorganic material includes SiC, BN, Si3N4, AlN, ZnO, TiO x , any one of ZrO2, Ta2O5, Cr2O3, In2Se3, Si or Ge, or a combination of at least two of them.

3. The bonding layer of a carrier wafer for photonic debonding according to claim 1 or 2, characterized in that: The inorganic heat-conducting layer includes a second inorganic material, and the thermal expansion coefficient of the second inorganic material is 3×10 -6 ~1×10 -5 / ℃; Preferably, the second inorganic material has a temperature tolerance of ≥700°C; Preferably, the second inorganic material is selected from opaque materials; Preferably, the second inorganic material includes any one of a non-metallic material, a metallic material, or an alloy material, or a combination of at least two thereof; Preferably, the non-metallic material comprises a carbon material; Preferably, the metal material includes any one or a combination of at least two of W, Ta, Mo, Cr, Zr or Ti; Preferably, the alloy material includes any one of Ti alloy, W alloy, Mo alloy or Ni alloy, or a combination of at least two of them.

4. The bonding layer of a carrier wafer for photonic debonding according to claim 1, characterized in that: The total thickness of the bonding layer is 0.15 to 5 μm; Preferably, the thickness of the inorganic dielectric layer is 20 to 100 nm; Preferably, the thickness of the inorganic heat conductive layer is 0.1 to 5 μm; Preferably, the roughness of the surface of the inorganic heat-conducting layer away from the transparent carrier wafer is ≤50nm; Preferably, the light absorbance of the bonding layer in a preset spectral range is ≥50%; Preferably, the transmittance of the bonding layer in a preset spectral range is ≤0.1%.

5. A method for preparing a bonding layer of a carrier wafer for photon debonding according to any one of claims 1 to 4, characterized in that: The preparation method comprises: An inorganic dielectric layer is arranged on at least one side surface of the transparent carrier, and then an inorganic heat conductive layer is arranged on the surface of the inorganic dielectric layer to obtain a bonding layer of the carrier wafer for photon debonding.

6. A wafer bonding structure, characterized in that: The wafer bonding structure includes a first wafer, a second wafer, and a bonding structure between the first wafer and the second wafer; The first wafer comprises a transparent carrier having a bonding layer according to any one of claims 1 to 4, and the second wafer comprises a device wafer having an organic bonding layer on a surface to be bonded; The bonding layer and the organic adhesive layer are bonded to each other to form the bonding structure.

7. The wafer bonding structure according to claim 6, wherein: The bonding strength between the bonding surface and the organic bonding layer is 0.1 to 5 N / 30 mm; Preferably, the thickness of the organic bonding layer is 2 to 200 μm; Preferably, the 5% thermal decomposition temperature of the organic bonding material in the organic bonding layer is ≥300°C.

8. A method for photon debonding, characterized in that: The photon debonding method is used for debonding the wafer bonding structure according to claim 6 or 7, and the photon debonding method comprises: Pulsed light is used to irradiate the first wafer in the wafer bonding structure to complete debonding of the first wafer and the second wafer.

9. The method of photon debonding according to claim 8, characterized in that: First, thinning the second wafer in the wafer bonding structure is performed, and then the first wafer in the wafer bonding structure is irradiated with pulsed light; Preferably, the thickness of the second wafer in the wafer bonding structure after thinning is ≤100 μm.

10. The photon debonding method according to claim 8, characterized in that: The spectral range of the pulsed light is 200 to 1200 nm; Preferably, the pulse duration of the pulse light is 50 to 5000 μs, preferably 100 to 300 μs; Preferably, the energy density of the pulsed light irradiated in the inorganic release material layer is ≤20 J / cm 2 , preferably 2 to 20 J / cm 2 ; Preferably, the spot overlap rate of the pulse light is ≤5%.

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