VCSEL chip wafer de-gluing method and system

Abstract

This invention relates to a method and system for removing adhesive from VCSEL chip wafers, belonging to the field of wafer adhesive removal technology. The method includes: penetrating and swelling the VCSEL chip wafer to be removed to obtain a swollen colloidal wafer; performing pressure-reducing phase change peeling on the swollen colloidal wafer to obtain a preliminary peeled wafer; performing photochemical bond breaking on the preliminary peeled wafer using a tunable ultraviolet light source to obtain a bond-broken adhesive residual wafer; performing gas-phase fluorination replacement on the bond-broken adhesive residual wafer to obtain a fluorinated residue wafer; performing momentum transfer purging on the fluorinated residue wafer to obtain a free residue wafer; and rinsing the free residue wafer with deionized water to obtain a adhesive-free target wafer. This method solves the technical problem that conventional methods are unable to effectively remove cross-linked adhesive residues adhering to the bottom and sidewalls of deep submicron patterned structures, leading to interface contamination or voids in subsequent deposition or bonding processes, which seriously affects device yield and reliability.

Description

Technical Field

[0001] This invention relates to the field of wafer resist removal technology, and in particular to a method and system for resist removal from VCSEL chip wafers. Background Technology

[0002] In the manufacturing process of VCSEL (Vertical-Cavity Surface-Emitting Laser) chips, photoresist removal is one of the key process steps. Currently, the mainstream photoresist removal method typically employs a combination of plasma ashing and wet chemical cleaning: first, oxygen plasma is used to oxidize and decompose the photoresist on the wafer surface, followed by immersion and rinsing with organic solvents or strong acidic solutions (such as a sulfuric acid-hydrogen peroxide mixture) to remove residues. This method is widely used in compound semiconductor wafer processing, especially suitable for material systems with good thermal stability, and has been successfully applied in traditional GaAs-based VCSEL production lines.

[0003] However, as VCSEL device structures become increasingly complex, mesa dimensions continue to shrink, and requirements for surface cleanliness and material integrity increase, existing resist removal processes have revealed significant defects: plasma treatment can easily cause irreversible oxidation of the high-aluminum AlGaAs component in the VCSEL epitaxial layer, while highly corrosive wet cleaning may cause sidewall corrosion or damage to the metal electrodes; more importantly, conventional methods are difficult to effectively remove cross-linked residual adhesive adhering to the bottom and sidewalls of deep submicron patterned structures, leading to interface contamination or voids in subsequent deposition or bonding processes, which seriously affects device yield and reliability. Summary of the Invention

[0004] The purpose of this invention is to at least partially solve one of the technical problems existing in the prior art.

[0005] To achieve the above objectives, the present invention provides a method for removing adhesive from a VCSEL chip wafer, comprising the following steps: The VCSEL chip wafer to be de-adhesive is permeated and swollen to obtain a swollen colloidal wafer; Based on the swollen colloidal wafer, a pressure-reducing phase change peeling is performed to obtain the initial peeled wafer; Photochemical bond breaking is performed on the initially stripped wafer using a tunable ultraviolet light source to obtain a bond-broken residual adhesive wafer. Based on the bond-broken residual glue wafer, a vapor-phase fluorination replacement was performed to obtain a fluorinated residue wafer; The fluorinated residue wafer is subjected to momentum transfer purging to obtain a free residue wafer; The wafer with the free residue is rinsed with deionized water to obtain a glue-free target wafer.

[0006] This invention also provides a VCSEL chip wafer resist removal system, comprising: The swelling module is used to permeate and swell the VCSEL chip wafers to be de-adhesive-removed to obtain swollen colloidal wafers. The stripping module is used to perform pressure-reducing phase change stripping on the swollen colloidal wafer to obtain a preliminary stripped wafer. The bond-breaking module is used to perform photochemical bond breaking on the initially peeled wafer using a tunable ultraviolet light source to obtain a bond-broken residual adhesive wafer. The replacement module is used to perform vapor-phase fluorination replacement based on the bond-broken residual adhesive wafer to obtain a fluorinated residue wafer; The purging module is used to perform momentum transfer purging on the fluorinated residue wafer to obtain a free residue wafer. The rinsing module is used to rinse the free residue wafer with deionized water to obtain a glue-free target wafer.

[0007] This invention provides a method for removing resist from a VCSEL chip wafer, comprising: infiltrating and swelling the VCSEL chip wafer to be removed to obtain a swollen colloidal wafer; performing pressure-reducing phase change peeling on the swollen colloidal wafer to obtain a preliminary peeled wafer; performing photochemical bond breaking on the preliminary peeled wafer using a tunable ultraviolet light source to obtain a bond-broken residual resist wafer; performing gas-phase fluorination replacement on the bond-broken residual resist wafer to obtain a fluorinated residue wafer; performing momentum transfer purging on the fluorinated residue wafer to obtain a free residue wafer; and rinsing the free residue wafer with deionized water to obtain a final product. Adhesive-free target wafers solve the technical problem that conventional methods struggle to effectively remove cross-linked adhesive residues adhering to the bottom and sidewalls of deep submicron patterned structures, leading to interface contamination or voids in subsequent deposition or bonding processes, severely impacting device yield and reliability. This technology achieves complete removal of adhesive residues across the entire deep submicron structure of VCSEL chip wafers (including the bottom of mesa, sidewall corners, and gaps in dense arrays), significantly reducing interface contamination and void defect density during subsequent dielectric deposition or wafer bonding processes. This greatly improves device packaging yield and substantially enhances long-term operational reliability. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 This is a schematic diagram of a VCSEL chip wafer resist removal method in one embodiment of the present invention; Figure 2 This is a structural block diagram of a VCSEL chip wafer resist removal system according to an embodiment of the present invention; The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0010] The embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. The step numbers in the following embodiments are set only for ease of explanation, and there is no limitation on the order between the steps. The execution order of each step in the embodiments can be adaptively adjusted according to the understanding of those skilled in the art.

[0011] The following describes in detail, with reference to the accompanying drawings, a method for removing adhesive from a VCSEL chip wafer according to an embodiment of the present invention.

[0012] Figure 1 This invention provides a method for removing adhesive from a VCSEL chip wafer, comprising the following steps: Step S1: The VCSEL chip wafer to be de-adhesive is permeated and swollen to obtain a swollen colloidal wafer; Step S2: Perform pressure-reducing phase change peeling on the swollen colloidal wafer to obtain the initial peeled wafer; Step S3: Photochemical bond breaking is performed on the initially peeled wafer using a tunable ultraviolet light source to obtain a bond-broken residual adhesive wafer; Step S4: Perform vapor-phase fluorination replacement on the broken bond residual wafer to obtain a fluorinated residue wafer; Step S5: Momentum transfer purging is performed on the fluorinated residue wafer to obtain a free residue wafer; Step S6: Rinse the free residue wafer with deionized water to obtain a glue-free target wafer.

[0013] Specifically, in this embodiment, when performing permeation swelling on the VCSEL chip wafer to be desizing, it is placed in a sealed reaction chamber, and a mixed solvent vapor composed of N-methylpyrrolidone and γ-butyrolactone is introduced. Under appropriate temperature and pressure conditions, the photoresist absorbs solvent molecules and expands significantly in volume, and the internal cross-linked network is stretched, thereby forming a swollen colloidal wafer. The key to this process lies in the selective permeation ability of the solvent on the colloidal material, ensuring sufficient swelling without causing the colloidal material to dissolve and be lost, especially in high aspect ratio mesa structure regions where permeation uniformity needs to be controlled.

[0014] During pressure-reducing phase change peeling based on the swollen colloidal wafer, the cavity pressure is rapidly reduced, causing the solvent retained within the swollen colloidal layer to flash vaporize. Because the vaporization process occurs simultaneously at multiple points within the colloidal layer, a local stress gradient is generated, causing the entire colloidal film to detach from the surface and sidewalls of the VCSEL epitaxial layer without leaving any thin layer or debris, thus obtaining the initial peeled wafer. This step avoids surface damage that may be caused by mechanical scratching or strong oxidation methods, and is particularly suitable for sensitive material systems containing high aluminum components.

[0015] Subsequently, the initially stripped wafer is photochemically broken using a tunable ultraviolet light source. The light source wavelength covers the deep ultraviolet range, precisely matching the absorption peaks of typical cross-linking bonds such as C–O and C–N in the residual adhesive. Under irradiation at a specific energy density, these chemical bonds break, and the large molecular residual adhesive depolymerizes into smaller molecular fragments, forming a bond-broken residual adhesive wafer. This process is highly selective and does not produce photo-etching or thermal effects on the underlying GaAs or AlGaAs material.

[0016] Based on this, the bond-broken adhesive residue wafer is subjected to gas-phase fluorination replacement. Fluorine-containing gas is introduced and excited in a low-temperature plasma environment. The generated fluorine radicals undergo a substitution reaction with the hydrocarbon structures in the adhesive residue fragments, generating volatile fluorocarbon compounds. These products are gaseous at room temperature and pressure and can be discharged through the exhaust system, ultimately leaving a fluorinated residue wafer containing only inorganic fluorides on the wafer surface, significantly reducing the difficulty of subsequent cleaning.

[0017] Next, the fluorinated residue wafer is subjected to momentum transfer purging. A high-speed inert gas microjet is used to scan close to the wafer surface, utilizing the collisions between gas molecules and micron-sized residue particles to achieve momentum transfer, causing the particles to detach from their adsorption sites and suspend in the gas flow. This method does not rely on a liquid medium, avoiding the particle redeposition problem caused by capillary forces, and is particularly suitable for the region between densely packed VCSEL mesas, thus obtaining a wafer with free residue.

[0018] Finally, the wafer with the free residue is rinsed with deionized water. High-purity deionized water is used to cover the entire wafer surface in a rotating spray manner. The water flow carries away the detached residue particles without introducing new ion contamination. After this step, the wafer surface is clean and free of adhesive, and the metal electrode areas are fully exposed, meeting the requirements of subsequent processes.

[0019] In this embodiment, the above-mentioned solution achieves step-by-step decomposition and non-destructive removal of residual adhesive in complex structural regions on VCSEL chip wafers, effectively avoiding damage to the high-aluminum epitaxial layer caused by traditional plasma or strong acid cleaning, and significantly improving the thoroughness of adhesive removal and device interface quality.

[0020] In a specific embodiment, the process of permeating and swelling the VCSEL chip wafer to be de-adhesive-treated to obtain a swollen colloidal wafer includes: Deep trench microfluidic permeation of the VCSEL chip wafer to be de-adhesive is performed using a gradient pressure supercritical fluid to obtain a fluid-saturated wafer. Based on the fluid-saturated wafer, the molecular pores of the phase change medium are filled to obtain the phase change pre-set wafer; The phase change pre-formed wafer is decoupled by hydrogen bonds in the residual adhesive crosslinking network through a megaacoustic frequency field to obtain a network destructured wafer. Polymer free volume expansion is performed on the aforementioned mesh-structured wafer to obtain a swollen colloidal wafer.

[0021] Specifically, in this embodiment, the process of penetrating and swelling the VCSEL chip wafer to be de-adhesive-treated is not carried out by conventional immersion, but by deep trench microfluidic penetrating using a gradient pressure-variable supercritical fluid. Specifically, the wafer is placed in a custom-designed microfluidic cavity, and supercritical carbon dioxide is introduced. A cyclical process of progressively increasing, holding, and decreasing pressure is applied near its critical point (approximately 35°C and 7.5 MPa), causing the fluid to form directional microflows within a dense trench structure with a mesa spacing of less than 5 micrometers and an aspect ratio exceeding 2:1. Because supercritical fluids possess both high gas diffusivity and high liquid solubility, they can penetrate deep into the bottom region of residual adhesive, which is difficult for traditional solvents to reach, thereby obtaining a fluid-saturated wafer.

[0022] Subsequently, the phase change medium molecular pores are filled based on the fluid-saturated wafer. At this point, a small amount of co-solvent, such as ethanol or acetone, is introduced into the cavity. Its molecular size is smaller than the pore size of the photoresist network, and it rapidly diffuses into the micropores inside the colloid under the carrying capacity of supercritical CO2. As the system pressure is slowly released to the subcritical region, the CO2 undergoes a gas-liquid phase transition, while the co-solvent is selectively retained in the colloid pores due to its polarity difference, completing the filling of the voids inside the polymer network and forming a phase change pre-set wafer. The key to this step is controlling the phase change rate to avoid cracking or uneven peeling of the adhesive layer due to abrupt volume changes.

[0023] Next, the hydrogen bonds of the residual adhesive crosslinking network in the phase transition pre-formed wafer were decoupled using a megasonic wave frequency field. A megasonic transducer was installed at the bottom of the cavity, with the excitation frequency set between 0.8 MHz and 1.2 MHz, and the power density maintained at approximately 2 W / cm². Under this high-frequency mechanical vibration, the hydrogen bond network formed by functional groups such as carboxyl and hydroxyl groups within the colloid was subjected to periodic shear stress. Some weak bonds broke, the crosslinking point density decreased, and the colloid gradually transformed from a rigid three-dimensional network into a loose structure with localized fluidity, thus obtaining a network-destructured wafer. It is noteworthy that the megasonic wave energy was strictly limited to affect only the organic adhesive layer without being transmitted to the underlying GaAs substrate, preventing dislocation multiplication in the epitaxial layer.

[0024] Based on this, polymer free volume expansion is performed on the aforementioned network-structured wafer. As the chain segment mobility increases after hydrogen bond decoupling, the co-solvent molecules previously filling the pores further penetrate into the polymer interchain gaps, increasing the interchain distance and significantly raising the free volume fraction. Simultaneously, the system temperature slowly rises to approximately 60°C, accelerating molecular thermal motion and causing isotropic volume expansion of the entire adhesive layer, ultimately forming a swollen colloidal wafer. The adhesive film on the wafer surface exhibits a noticeable bulge but remains unbroken, with micron-level gaps between the edges and the VCSEL mesa, creating the physical conditions for subsequent peeling.

[0025] There are clear temporal dependencies and physical state evolution relationships among the above sub-steps: the supercritical fluid first opens up the permeation channels, the phase change medium achieves precise pore filling, the megasonic wave weakens the network strength at the chemical bond level, and finally, macroscopic swelling is completed through the thermal-solvent synergistic effect. The entire process does not require strong acids, strong oxidants, or high-temperature plasma, and is particularly suitable for VCSEL wafers containing high aluminum components such as AlGaAs, which are prone to forming non-radiative recombination centers due to oxidation in traditional resist removal processes.

[0026] In this embodiment, the above-mentioned scheme achieves deep penetration and controllable swelling of residual adhesive in the high aspect ratio VCSEL structure through multi-physics field coupling control. This not only avoids chemical damage to the sensitive epitaxial layer, but also provides sufficient interface separation space for subsequent phase change stripping, significantly improving the integrity of adhesive removal and process compatibility.

[0027] In a specific embodiment, the step of performing a depressurization phase change peeling based on the swollen colloidal wafer to obtain a preliminary peeled wafer includes: A phase change vaporization wafer is obtained by step-pulse decompression of the swollen colloidal wafer through an isentropic expansion chamber, and an internal stress release is performed on the phase change vaporization wafer to obtain a bulk tearing wafer. The bulk phase torn wafer is subjected to high-frequency shear oscillation to obtain an interface decoupled wafer, and the bottom adhesion bond is broken based on the interface decoupled wafer to obtain a bottom wall desorbed wafer. The bottom-wall desorbed wafer is swept by a supersonic airflow to obtain a fragmented wafer, and gas-solid two-phase separation is performed based on the fragmented wafer to obtain a preliminary desorbed wafer.

[0028] Specifically, in this embodiment, the depressurization phase change stripping operation based on the swollen colloidal wafer begins with the introduction of an isentropic expansion chamber. This chamber is equipped with a pressure-grading control valve group, which can implement stepped pulse depressurization on the fully swollen VCSEL chip wafer: the initial pressure is maintained at 0.35 MPa, then successively reduced to 0.2 MPa, 0.1 MPa, and finally 5 kPa at 50 ms intervals, with the holding time for each stage controlled within 80 ms. During this process, the volatile solvent retained in the swollen colloid undergoes local flash evaporation due to the sudden drop in ambient pressure, forming a large number of micron-sized bubbles. The colloid volume rapidly expands and generates an internal vaporized phase, thereby obtaining a phase change vaporized wafer. This stepped depressurization method avoids the colloid layer bursting and splashing caused by a single rapid depressurization, ensuring uniform nucleation within the colloid during the vaporization process.

[0029] Next, the intrinsic stress is released based on the phase change vaporization wafer. Due to the non-uniform distribution of bubbles in the colloidal three-dimensional network, significant tensile and shear stresses accumulate in local areas during its growth. When the stress exceeds the yield strength of the polymer chain segments, microcracks propagate and pores connect within the colloidal structure, macroscopically manifesting as bulk tearing of the overall structure, thus obtaining a bulk-torn wafer. This tearing is not random but preferentially occurs along the most swollen regions, especially forming continuous peeling paths at the VCSEL mesa sidewalls and bottom corners, laying the foundation for subsequent interface decoupling.

[0030] Subsequently, high-frequency shear oscillations were applied to the bulk-torn wafer. A piezoelectric ceramic actuator integrated within the cavity excited a horizontal shear wave with a frequency of 1.1 MHz and an amplitude of approximately 200 nm for 45 seconds. This vibrational energy was conducted through the back of the wafer to the colloidal-semiconductor interface, amplifying the relative displacement in the region with existing micro-gap, weakening van der Waals forces and dipole interactions, and further decoupling the colloidal fragments from the epitaxial layer surface, forming an interface-decoupled wafer. Notably, the oscillation frequency avoided the mechanical resonance peak of the GaAs substrate, preventing lattice damage.

[0031] Based on this, the underlying adhesion bonds are broken using the interface-decoupled wafer. Although the colloids have macroscopically separated, a small number of C–O–Ga or C–O–Al chemisorption bonds still exist at the atomic scale. By briefly introducing low-power Ar plasma (80 W RF power, 8 seconds processing time), the residual bonding points at the interface are selectively bombarded, causing the underlying adhesion bonds to break, resulting in a bottom-wall desorbed wafer. The plasma energy is strictly limited to acting only on the surface layer at a depth of a few nanometers, without reaching the underlying active region.

[0032] Subsequently, the bottom-wall desorbed wafer is swept with a supersonic gas flow. Nitrogen gas is accelerated to Mach 1.3 through a Laval nozzle, with the nozzle maintained 3 mm from the wafer surface, and the entire surface is scanned in a spiral trajectory. The high-speed gas flow forms a low-pressure vortex region around the colloidal debris, utilizing the Bernoulli effect to "suck" it out from the mesa gaps, achieving debris lifting and obtaining a debris-lifted wafer. This process is particularly suitable for VCSEL arrays with a pitch of less than 6 micrometers, and can also effectively remove slit debris that is difficult to remove with conventional washing.

[0033] Finally, gas-solid two-phase separation is performed on the fragmented wafer. The cavity outlet is connected to a cyclone separator and a high-efficiency filter unit. Colloidal particles carried by the airflow are captured by centrifugal force and the interception of the filter membrane, and clean gas is discharged. Only a small amount of loose adhering material remains on the wafer surface, which is the initial stripped wafer. The entire stripping process does not use a liquid medium, eliminating the re-adhesion problem caused by capillary bridging.

[0034] In this embodiment, the above-mentioned scheme achieves controllable peeling from bulk tearing to complete interface desorption through the multi-level synergistic effect of pressure gradient, mechanical vibration and pneumatic sweeping. It effectively solves the technical problem of the difficulty in removing residual adhesive in the high aspect ratio VCSEL structure as a whole, and provides a clean and undamaged substrate surface for the subsequent photochemical bond breaking step.

[0035] In a specific embodiment, the step of photochemically breaking bonds on the initially peeled wafer using a tunable ultraviolet light source to obtain a bond-broken residual adhesive wafer includes: A photon-excited wafer is obtained by injecting photon energy in a characteristic frequency band into the initially stripped wafer using a tunable ultraviolet light source. Based on the photon-excited wafer, multiphoton resonance absorption is performed to obtain a high-energy state residual adhesive wafer; The high-energy state residual glue wafer is subjected to non-thermal relaxation bond breaking using a nanosecond pulse modulator to obtain a chain-broken residual glue wafer, and a three-dimensional cross-linked network depolymerization is performed based on the chain-broken residual glue wafer to obtain a short-chain residue wafer. The short-chain residue wafer is subjected to free radical quenching by a low-temperature inert gas flow to obtain a quenched residue wafer; Spatial steric rearrangement is performed on the quenched residue wafer to obtain a bond-broken residue wafer.

[0036] Specifically, in this embodiment, a tunable ultraviolet light source is used to perform photochemical bond breaking on the initially stripped wafer. This relies on a wavelength-tunable excimer laser with an output wavelength covering the range of 210 nm to 280 nm, corresponding to photon energies of 4.43 eV to 5.90 eV. After being filtered by a monochromator, the center wavelength of this light source is set at 248 nm (corresponding to the KrF excited state) to match the electronic transition absorption peaks of the C–O, C–N, and C–C main chain bonds in typical g / i line photoresist. The wafer is placed in a nitrogen-protected quartz cavity, and the laser beam is uniformly irradiated onto the surface at a 5° incident angle, with the energy density controlled at 120 mJ / cm², the pulse repetition frequency set to 200 Hz, and continuous irradiation for 30 seconds. This allows the residual adhesive molecules to absorb sufficient energy to enter the excited state, forming a photon-excited wafer.

[0037] Subsequently, multiphoton resonance absorption is performed on the photon-excited wafer. Due to the high local light intensity and the colloid's already swollen and porous state, two-photon or three-photon simultaneous absorption processes occur in some regions. That is, multiple low-energy photons work together to provide an excitation energy higher than the single-photon energy threshold. For example, under 248 nm illumination, the combined energy of two photons reaches 11.8 eV, which is sufficient to break aromatic ring side chains or cross-linking bridge bonds with bond energies of about 7–9 eV. This nonlinear absorption effect is unevenly distributed within the colloid, preferentially occurring in regions with larger free volumes, prompting the molecules as a whole to transition to higher energy states, thus obtaining a high-energy residual colloid wafer.

[0038] Next, precisely time-controlled ultraviolet pulses are applied to the high-energy residual adhesive wafer using a nanosecond pulse modulator. The modulator, consisting of an electro-optic switch and a delay line, cuts the continuous laser stream into discrete pulse sequences with a width of 8 ns and an interval of 50 ns. This short-duration, high-energy input prevents excited-state molecules from dissipating energy through thermal conduction, instead causing electron-vibrational coupling instability within the picosecond range, leading to direct breakage of covalent bonds—a process known as non-thermal relaxation bond breaking. The breakage mainly occurs at tertiary carbon sites or ester bonds in the polymer backbone, generating numerous fragments with free radical end groups, thus yielding a chain-broken residual adhesive wafer.

[0039] Based on this, a three-dimensional cross-linked network depolymerization was performed on the broken-chain residual wafer. Because the main chain breakage weakened the network topological constraints, the originally locked branches began to rearrange their conformations, and the cross-linking points gradually dissociated. Under the combined effects of continuous light irradiation and thermal perturbation (cavity temperature maintained at 45°C), the macromolecular network disintegrated into oligomers with molecular weights below 2000 Da, forming short-chain residual wafers. These short-chain products still adhered to the inter-mesa gaps of the VCSEL, but had lost their original viscoelasticity.

[0040] Subsequently, the short-chain residue wafer is subjected to free radical quenching using a low-temperature inert gas flow. Liquid nitrogen pre-cooling is introduced into the cavity sidewalls. High-purity argon gas at 30°C, with a flow rate set at 3 L / min, forms a laminar flow covering the wafer surface. The low-temperature environment significantly reduces the activity of free radicals, causing them to rapidly combine with trace amounts of water and oxygen in the environment or with each other to terminate the chain reaction, avoiding secondary cross-linking, and ultimately obtaining a wafer with quenched residue.

[0041] Finally, steric rearrangement is performed on the quenched residue wafer. As the free radical reaction terminates, short-chain molecules tend towards the lowest energy configuration driven by van der Waals forces, and side groups are reoriented toward the wafer surface, increasing the steric hindrance to the substrate and weakening the adsorption force. This spontaneous rearrangement process lasts for about 2 minutes, causing the residue to change from a tightly adhered state to a loosely packed state, i.e., the bond-broken residue wafer.

[0042] In this embodiment, the above-mentioned scheme achieves full-process control from photoexcitation to selective covalent bond breaking and then to residue structure relaxation by precisely controlling photon energy, pulse timing, and thermodynamic environment. This effectively avoids the Al0.9Ga0.1As oxidation problem caused by heat accumulation in traditional UV cleaning, providing a chemically active and physically easily removable precursor for the subsequent fluorination replacement step. Furthermore, Al0.9Ga0.1As is a ternary compound semiconductor material, belonging to the aluminum gallium arsenide (Al₂O₃) group. x Ga1 x One of the As series.

[0043] In a specific embodiment, the step of performing three-dimensional cross-linked network depolymerization based on the broken-chain residue wafer to obtain a short-chain residue wafer includes: The broken-chain residual adhesive wafer is subjected to high-frequency oscillation of molecular chain segments to obtain a physically untangled wafer, and local thermal stress is induced based on the physically untangled wafer to obtain a network relaxation wafer; By performing cross-linking node solvation intercalation on the network relaxation wafer using a supercritical polar fluid, a dipole-effect wafer is obtained. Based on the dipole-effect wafer, the network pores are expanded and enlarged to obtain a swollen and expanded wafer. The swollen and expanded wafer is injected with highly reactive oxygen free radicals in a gas-phase ozone field to obtain a targeted oxidation wafer, and the cross-linked bonds are broken and sheared in situ based on the targeted oxidation wafer to obtain a short-chain residue wafer.

[0044] Specifically, in this embodiment, the three-dimensional crosslinked network depolymerization operation based on the broken polymer wafer begins with high-frequency oscillation of molecular chain segments. This process is achieved by a piezoelectric ceramic actuator installed under the wafer stage, with a driving frequency set to 1.3 MHz, an amplitude controlled at 150 nm, and an action time lasting 40 seconds. Under this high-frequency mechanical excitation, the broken but not completely separated polymer chain segments undergo violent lateral oscillation, and the physical entanglement points between them gradually untangle due to shear force exceeding a critical threshold, forming a physically detangled wafer. This detangling is not chemical degradation, but rather a breaking of the inter-chain adsorption dominated by van der Waals forces through kinetic perturbation, especially in the dense region of the VCSEL mesa, where the originally "locked" short chains are released with local degrees of freedom.

[0045] Subsequently, localized thermal stress was induced based on the physical unwrapped wafer. An infrared laser array was integrated into the cavity, with a wavelength selected at 1.55 μm to match the vibrational absorption band of the C–H bonds in the residual adhesive. The spot diameter was 2 mm, the scanning speed was 5 mm / s, and the power density was maintained at 0.8 W / cm². Due to the reduced thermal conductivity of the chain segments after unwrapping, the temperature rapidly rose to approximately 90°C after localized light absorption, while the surrounding unirradiated areas remained at room temperature. This generated a micrometer-scale temperature gradient, inducing non-uniform thermal expansion. This thermal stress concentrated near the original crosslinking nodes, causing elastic relaxation of the network structure, resulting in a network-relaxed wafer. Notably, the heat input was strictly limited to a range that would not cause thermal deformation of the GaAs substrate.

[0046] Next, the network-relaxed wafer is solvated and intercalated at crosslinked nodes using a supercritical polar fluid. The fluid used is supercritical methanol (critical temperature 239°C, critical pressure 8.1 MPa), which is introduced into the reaction chamber at 250°C and 9 MPa for 15 minutes. Methanol molecules, with their strong polarity and small size (kinetic diameter approximately 0.36 nm), can penetrate into the pores of the relaxed network and preferentially adsorb at residual ester or ether crosslinked points. Through dipole-dipole interactions, the electron cloud density of covalent bonds is weakened, achieving solvation and intercalation to form a dipole-intercalated wafer. The key to this step lies in utilizing the high diffusion coefficient of the supercritical state (approximately 10⁻⁶). -7 m² / s) ensures fluid penetration into submicron trenches.

[0047] Based on this, the network pores of the dipole-effect wafer were expanded. As methanol molecules accumulated around the crosslinking points, their volume repulsion effect forced an increase in the spacing between adjacent chain segments, expanding the pore diameter from the initial 1.2 nm to over 2.8 nm, and increasing the overall adhesive layer thickness by approximately 18%, thus obtaining a swollen and expanded wafer. This expansion provided the necessary channels for subsequent oxidant penetration, especially near the Al0.9Ga0.1As sidewalls, avoiding cleaning blind zones caused by pore closure.

[0048] Subsequently, highly reactive oxygen radicals were injected into the swollen and expanded wafer using a gas-phase ozone field. Ozone was generated on-site using a dielectric barrier discharge generator at a concentration controlled at 800 ppm. It was mixed with high-purity nitrogen and introduced into the cavity at a flow rate of 5 L / min. Simultaneously, a 254 nm ultraviolet lamp was used for irradiation to promote the photolysis reaction O3 → O(¹D) + O2, generating a large number of hydroxyl radicals (·OH) and singlet oxygen (¹O2). These reactive species rapidly diffused into the colloidal interior through the expanded pores, undergoing hydrogen abstraction reactions at easily oxidized sites such as tertiary carbon and benzyl groups, forming peroxide intermediates and obtaining a targeted oxidized wafer. The oxidation process was highly selective, primarily attacking the residual adhesive rather than the underlying semiconductor material.

[0049] Finally, in-situ shearing of crosslinked bonds is performed on the targeted oxide wafer. The peroxide decomposes spontaneously at room temperature, releasing oxygen and accompanied by local volume expansion, which applies shear stress to adjacent crosslinked bonds. At the same time, the C–O–C or C–C crosslinked bonds are weakened by the oxidation of electron clouds, resulting in a decrease in bond energy. Under mechanical perturbation, homogeneous cleavage occurs, ultimately completely shearing the three-dimensional network into water-soluble short-chain fragments with a molecular weight of less than 1500 Da, i.e., short-chain residue wafers.

[0050] In this embodiment, the above-mentioned scheme achieves deep depolymerization of the three-dimensional network of residual adhesive after chain breakage through a multi-level synergistic mechanism of mechanical unwinding, thermal stress relaxation, polar solvent intercalation and targeted oxidation. This not only significantly reduces the molecular weight and adhesion strength of the residue, but also avoids non-selective corrosion of the high-aluminum VCSEL epitaxial layer, creating an ideal chemical precursor state for subsequent low-temperature fluorination replacement.

[0051] In a specific embodiment, the step of performing vapor-phase fluorination replacement based on the bond-broken residual wafer to obtain a fluorinated residue wafer includes: The broken bond residual glue wafer is targeted molecularly adsorbed by a gas phase molecular diffusion source to obtain a fluorine source attached wafer, and surface chemical coordination is performed based on the fluorine source attached wafer to obtain a reaction precursor wafer. The precursor wafer is selectively fluorinated and substituted using a stepped thermal field generator to obtain a fluorocarbon conversion wafer, and polar groups are eliminated based on the fluorocarbon conversion wafer to obtain a low surface energy wafer. The low surface energy wafer is subjected to isothermal sublimation phase transition by a differential pressure desorption controller to obtain an in-situ desorbed wafer, and gas-solid phase separation is performed based on the in-situ desorbed wafer to obtain a fluorinated residue wafer.

[0052] Specifically, in this embodiment, the gas-phase fluorination replacement operation based on the bond-broken residual wafer first achieves targeted molecular adsorption through a gas-phase molecular diffusion source. The fluorine source used is perfluorotert-butanol ((CF3)3COH), which is fed with a high-purity nitrogen gas stream at 60°C via a bubbler to form a mixed gas with a concentration of 1.2 vol%, which is then introduced into the reaction chamber. Since the surface of the bond-broken residual wafer is rich in polar end groups such as hydroxyl and carboxyl groups, and perfluorotert-butanol molecules have strongly electronegative fluorine atoms and weak acidic protons, they can selectively adsorb onto the surface of the residual fragments at room temperature (25°C) through hydrogen bonding and dipole interactions, forming a fluorine source-attached wafer after 30 minutes. This adsorption process preferentially occurs at the active sites of the short-chain residues, rather than the underlying Al0.9Ga0.1As or GaAs epitaxial layer, demonstrating good material selectivity.

[0053] Subsequently, surface chemical coordination was performed on the fluorine source-attached wafer. A slight positive pressure (105 kPa) was maintained within the chamber, and the temperature was raised to 85°C, promoting the reaction of oxygen atoms in the adsorbed perfluorotert-butanol molecules with residual metal ion impurities (such as Na+) in the residual adhesive. + Fe³ + The fluorine source can undergo Lewis acid-base coordination at the carbocation center to form a stable five-membered ring transition complex, thereby obtaining the precursor wafer. This coordination structure not only fixes the fluorine source position but also activates the adjacent C–H bonds, creating a favorable electronic environment for subsequent fluorination substitution.

[0054] Next, selective fluorination substitution was performed on the precursor wafer using a stepped thermal field generator. This thermal field consisted of a multi-zone infrared heating array, with three temperature-programmed stages: the first stage was held at 110°C for 5 minutes to induce O–H bond breakage and generate alkoxy radicals; the second stage was held at 145°C for 8 minutes to trigger β-fracture and release ·CF3 radicals; the third stage was held at 170°C for 6 minutes, allowing ·CF3 to attack the tertiary carbon or benzylic C–H bonds in the residual resin, resulting in a radical substitution reaction that replaced hydrogen atoms with –CF3 or –CF2– groups, generating fluorinated carbon segments, i.e., the fluorocarbon-converted wafer. The entire process avoided exceeding 180°C to prevent thermal oxidation of Al0.9Ga0.1As.

[0055] Based on this, polar groups are eliminated using the fluorocarbon-converted wafer. With the introduction of a large number of fluorine atoms, hydrophilic groups such as –OH and –COOH in the original residue are replaced by hydrophobic groups such as –CF3 and –OCF3, significantly reducing the molecular dipole moment and lowering the surface energy from the initial 42 mN / m to below 14 mN / m, forming a low surface energy wafer. This transformation causes a sharp increase in the interfacial tension between the residue and the semiconductor surface, providing a thermodynamic driving force for subsequent desorption.

[0056] Subsequently, the low surface energy wafer undergoes an isothermal sublimation phase transition using a differential pressure desorption controller. The controller first evacuates the cavity to 5 Pa, then instantaneously introduces high-purity argon gas to atmospheric pressure, creating a transient differential pressure pulse (ΔP ≈ 10). 5 Pa), while maintaining the wafer temperature constant at 160°C. Under these conditions, the fluorinated residue experiences an increase in vapor pressure (>10 Pa). - The wafer is directly sublimated from solid to gas (at 160℃) without passing through a liquid phase, avoiding redeposition caused by capillary forces, resulting in in-situ desorbed wafers. This sublimation process is particularly effective in high aspect ratio areas such as the sidewalls of VCSEL mesa, and can also clean areas that are difficult to reach with traditional rinsing.

[0057] Finally, gas-solid phase separation is performed based on the in-situ desorbed wafer. The cavity outlet is connected to a cold trap ( The wafer is treated with a 78℃ dry ice / acetone bath and a particulate filter (0.02 μm pore size). The gaseous fluorination products are sublimated and captured in the cold trap, and the unreacted gas is discharged through the filter membrane. Only trace amounts of non-volatile ash remain on the wafer surface, which is the fluorination residue wafer.

[0058] In this embodiment, the above-mentioned scheme achieves efficient fluorination and in-situ removal of residual adhesive after photochemical bond breaking through a cascade reaction path of molecular recognition adsorption, coordination activation, stepwise thermal control fluorination and isothermal sublimation desorption. This not only completely eliminates organic residues but also avoids the corrosion risk of high-aluminum VCSEL devices by wet cleaning, significantly improving chip yield and optical interface cleanliness.

[0059] In a specific embodiment, the step of eliminating polar groups based on the fluorocarbon conversion wafer to obtain a low surface energy wafer includes: The fluorocarbon conversion wafer is activated by polar bond complexation using a gas-phase Lewis acid source to obtain a complex activated wafer, and then protonation fracture desorption is performed on the complex activated wafer to obtain a polar decoupled wafer. The polar decoupled wafer is passivated in situ by dangling bonds using a pulsed fluorine radical beam to obtain a fluorine-based grafted wafer, and then the fluorine-carbon chain segments are spatially rolled up based on the fluorine-based grafted wafer to obtain a hydrophobic shielding wafer. The hydrophobic shielding wafer is weakened by the van der Waals forces at the interface to obtain an interface-slip wafer, and the surface free energy is minimized based on the interface-slip wafer to obtain a low surface energy wafer.

[0060] Specifically, in this embodiment, the operation of eliminating polar groups based on the fluorocarbon-converted wafer begins with the introduction of a gas-phase Lewis acid source. The Lewis acid used is a boron trifluoride diethyl ether complex (BF3·OEt2), which is carried into the reaction chamber at 45°C by a carrier gas (high-purity N2, flow rate 2 L / min) to form a gas-phase environment with a concentration of 0.8 vol%. A small amount of incompletely substituted –OH or –COOH groups remain on the surface of the fluorocarbon-converted wafer. The lone pairs of electrons in these polar bonds can coordinate with the empty p orbitals in BF3 to form a four-coordinate boron-oxygen complex, thereby achieving polar bond activation complexation and obtaining a complexed activated wafer. This complexation process takes place at room temperature for 10 minutes, preferentially occurring at the edges of residual adhesive fragments or defect sites, without affecting the underlying Al0.9Ga0.1As epitaxial layer.

[0061] Subsequently, protonation fracture desorption is performed based on the complexed activated wafer. A trace amount of water vapor (partial pressure approximately 30 Pa) is introduced into the cavity, and the H+ generated by the dissociation of water molecules... + The attack on the B–O bonds in the complex structure induces the desorption of –OH or –COOH groups as H2O or CO2, while simultaneously releasing BF3 for regeneration. This protonation process is sustained at 60°C for 8 minutes, completely removing residual polar groups from the surface and forming a polar decoupled wafer. The desorption products are discharged with the gas flow, leaving only perfluoroalkyl fragments on the surface, with virtually no hydrophilic functional groups remaining on the carbon backbone.

[0062] Next, the polar decoupled wafer undergoes in-situ passivation of dangling bonds using a pulsed fluorine radical beam. Fluorine radicals are generated by microwave-excited F2 / N2 mixed gas (5% F2), forming a beam through a quartz nozzle. The pulse width is set to 200 ns, the repetition frequency to 5 kHz, and the beam energy to 3.2 eV. These highly reactive ·F radicals rapidly combine with residual carbon dangling bonds on the surface to form stable C–F single bonds, completing the fluorine grafting and obtaining a fluorine-grafted wafer. This step effectively prevents re-crosslinking caused by radical recombination during subsequent processing, especially in high-curvature regions such as the VCSEL mesa sidewalls, where the passivation coverage can reach over 98%.

[0063] Based on this, the fluorine-based grafted wafer undergoes spatial coiling of fluorocarbon segments. Due to the strong electronegativity and large van der Waals radius of the –CF3 and –CF2– groups, a significant stereorepulsion effect occurs between adjacent fluorocarbon chains. Under thermal perturbation (cavity temperature maintained at 75°C), they spontaneously adopt helical or folded conformations to reduce the system energy, resulting in local enrichment of fluorine atom density on the surface, forming a dense hydrophobic layer, i.e., a hydrophobic shielding wafer. This coiled structure is similar to the low-energy surface arrangement of polytetrafluoroethylene (PTFE), and the contact angle can be increased to over 112°.

[0064] Subsequently, the hydrophobic shielding wafer is subjected to interfacial van der Waals force weakening. Due to the highly ordered nature of the fluorocarbon segments and the uniform distribution of electron clouds, the dispersion force between them and the underlying GaAs or Al0.9Ga0.1As surface atoms is significantly weakened, and the interfacial adhesion work decreases from the initial 85 mJ / m² to below 28 mJ / m², forming an interfacial slip wafer. At this point, only weak physical adsorption exists between the residue and the substrate, making it extremely easy to detach under external force or airflow disturbance.

[0065] Finally, the surface free energy was minimized based on the interface-slip wafer. After standing in an inert atmosphere for 5 minutes, the surface fluorocarbon chains further relaxed to the thermodynamically stable state, the molecular orientation tended to be consistent, the dipole moments canceled each other out, and the overall surface free energy stabilized in the range of 12–14 mN / m, ultimately yielding a low surface energy wafer.

[0066] In this embodiment, the above-mentioned scheme achieves the complete removal of polar groups and reconstruction of ultra-low energy states on the surface of fluorocarbon-converted wafers through a multi-level chemical-physical synergistic mechanism of Lewis acid complexation activation, proton desorption, fluorine radical passivation and segment self-assembly. This not only significantly weakens the adhesion strength between the residue and the VCSEL device surface, but also provides ideal thermodynamic and kinetic conditions for the subsequent pressure difference desorption step, effectively avoiding device damage caused by sudden changes in interfacial tension in traditional cleaning.

[0067] In a specific embodiment, the step of performing carbon-fluorine chain segment spatial curling based on the fluorine-based grafted wafer to obtain a hydrophobic shielding wafer includes: By using a frequency-converted microwave field to excite the deep trench sidewalls of the fluorine-based grafted wafer with dipole moment resonance, a dipole-excited wafer is obtained. Based on the dipole-excited wafer, carbon-fluorine bond steric hindrance repulsion is performed to obtain a conformationally unstable wafer. A polar cladding wafer is obtained by thermodynamically isolating the conformationally unstable wafer with a polar microenvironment through a phase change-induced fluid, and a nanocluster wafer is obtained by self-assembling and shrinking polymer segments based on the polar cladding wafer. The nanocluster wafer is subjected to a contact line shrinkage phase transition to obtain a point contact wafer, and surface tension curing is performed on the point contact wafer to obtain a hydrophobic shielding wafer.

[0068] Specifically, in this embodiment, the operation of spatially curling carbon-fluorine segments based on the fluorine-based grafted wafer first involves applying a frequency-modulated microwave field to the sidewalls of the deep trench for dipole moment resonant excitation. The microwave source frequency can be continuously tuned between 2.45 GHz and 5.8 GHz, the power density is set to 18 W / cm², and the duration is 12 seconds. Because the C–F bonds on the surface of the fluorine-based grafted wafer have a significant dipole moment (approximately 1.41 D), when the microwave electric field frequency matches the C–F bond rotation relaxation frequency (measured peak value around 4.2 GHz), the fluorine-carbon segments in the sidewall residue undergo resonant absorption, and the molecular dipoles oscillate at high frequency along the electric field direction, forming local orientation polarization, thereby obtaining a dipole-excited wafer. This process is particularly suitable for trench regions with an aspect ratio greater than 5:1 between VCSEL mesa, ensuring effective energy coupling to the hard-to-reach sidewalls.

[0069] Subsequently, steric repulsion of carbon-fluorine bonds was performed on the dipole-oscillating wafer. As the dipole oscillation intensified, the overlap of van der Waals radii between adjacent –CF3 groups led to strong stereorepulsion, with repulsion energies reaching 3–5 kJ / mol, far exceeding the room-temperature thermal perturbation kinetic energy (approximately 2.5 kJ / mol). This repulsion forced the originally extended perfluoroalkyl chain to undergo conformational distortion, with part of the C–C backbone changing from the trans configuration to the gauche configuration. The overall chain conformation lost stability, forming a conformationally unstable wafer. This transformation was particularly pronounced at the bottom of the trench, where the confined space amplified the interchain interactions.

[0070] Next, a polar microenvironment thermodynamic isolation was implemented for the conformationally unstable wafer using a phase change-induced fluid. The fluid used was a mixture of liquid carbon dioxide and a small amount of hexafluoroisopropanol (HFIP, molar fraction 0.6%), injected into the cavity in a supercritical state at 31°C and 7.5 MPa, and maintained for 10 minutes. HFIP, as a strong hydrogen bond acceptor, can encapsulate residual trace amounts of polar impurities, while supercritical CO2 provides a nonpolar continuous phase. Together, they construct a low dielectric constant (ε ≈ 1.6) microregion around the fluorocarbon segments, achieving a polar encapsulated wafer. This isolation layer effectively shields against external water and oxygen interference while reducing the activation energy of segment movement.

[0071] Based on this, polymer segment self-assembly shrinkage is performed on the polar-clad wafer. Driven by thermal perturbation (cavity temperature rises to 65°C), the fluorocarbon segments spontaneously aggregate to minimize interfacial free energy, forming spherical aggregates with a diameter of approximately 8–12 nm, i.e., nanocluster wafers. These clusters are arranged with –CF3 facing outward and the carbon skeleton facing inward, similar to a microphase separation structure, and contact angle tests show a significant enhancement in surface hydrophobicity.

[0072] Subsequently, a contact line shrinkage phase transition is performed on the nanocluster wafer. The cavity pressure drops sharply to atmospheric pressure, and the supercritical fluid rapidly vaporizes, triggering a localized evaporative cooling effect. This causes the three-phase contact line (solid-liquid-gas) at the cluster edge to shrink back towards the center due to the surface tension gradient. This process lasts for approximately 3 seconds, during which the cluster transforms from a spread-out state to a discrete point-like attachment, forming a point-contact wafer. At this point, the actual contact area between the residue and the substrate is reduced to less than 15% of its original value.

[0073] Finally, surface tension curing was performed on the point-contact wafer. After standing in an inert atmosphere for 8 minutes, the internal chain segments of the nanoclusters further relaxed, and the surface tension drove them to form a stable hemispherical morphology, with the surface free energy locked at 13 mN / m, ultimately yielding a hydrophobic shielding wafer.

[0074] In this embodiment, the above scheme achieves the directional curling and nanoscale self-assembly of fluorocarbon segments on the sidewalls of deep trenches of VCSELs through multi-scale control of microwave dipole resonance excitation, steric hindrance-driven conformational instability, supercritical fluid microenvironment isolation, and contact line dynamic contraction. This not only constructs a highly stable low-energy surface but also significantly weakens the physical anchoring effect between the residue and the device interface, laying a structural foundation for subsequent non-destructive desorption.

[0075] In a specific embodiment, the step of performing momentum transfer purging on the fluorinated residue wafer to obtain a free residue wafer includes: The fluorinated residue wafer is subjected to momentum transfer collisions via pulsed ultracold aerosols to obtain collision desorption wafers. Based on the collision desorption wafer, in-situ sublimation expansion is performed to obtain a vapor-supported wafer; The gas-phase lifted wafer is hydrodynamically suspended by a gradient laminar flow field to obtain a suspended phase wafer, and a directional flow field is used to remove the free residue wafer based on the suspended phase wafer.

[0076] Specifically, in this embodiment, the momentum transfer purging operation on the fluorinated residue wafer begins with the introduction of a pulsed ultracold aerosol. The aerosol used is high-purity argon gas cooled by liquid nitrogen (…). The aerosol is generated by mixing CO2 particles (30–50 nm in diameter) with nanoscale solid CO2 particles at 150 °C. It is then injected in a pulsed mode through a piezoelectric nozzle with a pulse width of 200 μs, a repetition frequency of 1 kHz, and an exit velocity of 320 m / s. When this ultracold aerosol impacts the surface of the fluorinated residue wafer, the solid CO2 particles carry momentum and impact the residue particles perpendicularly. Through instantaneous inelastic collisions, the linear momentum is transferred to the fluorinated, low-adhesion residue, causing it to overcome the remaining van der Waals forces and detach from the substrate, forming a collisional desorption wafer. This process is particularly suitable for densely packed mesa areas of VCSELs because the aerosol particle size is much smaller than the trench width (typically 200 nm), allowing for deep penetration into the sidewalls for complete coverage.

[0077] Subsequently, in-situ sublimation expansion is performed based on the collision desorption wafer. The fluorinated residues that have detached but not yet been removed from the surface are in a solid state at a low temperature of 150 °C, but as the cavity temperature rises to room temperature (25 °C) within 0.5 seconds, its vapor pressure rapidly increases (>10 - ² Pa), and a direct solid-gas phase change occurs. This sublimation process is accompanied by a sharp volume expansion (expansion ratio of approximately 800:1), forming a local high-pressure air cushion under the residue, generating an upward lifting force that suspends the particles several micrometers above the wafer surface, obtaining a gas-phase lifted wafer. This effect is particularly significant above the Al0.9Ga0.1As epitaxial layer because most of the fluorinated products are low-molecular-weight compounds such as perfluoroalkanes, and the sublimation temperature is below 50 °C.

[0078] In addition, the Chinese name of Al0.9Ga0.1As is aluminum gallium arsenide, and more specifically, it can be called nine-aluminum-one-gallium arsenide or aluminum 0.9 gallium 0.1 arsenide.

[0079] In the field of semiconductor materials, it is usually directly called aluminum gallium arsenide (AlGaAs) according to the elemental composition, and the subscript ratio is used to indicate the mole fraction of each element. Therefore, Al0.9Ga0.1As indicates that this ternary compound is composed of 90% aluminum (Al), 10% gallium (Ga), and a fixed ratio of arsenic (As), belonging to a specific component of the aluminum gallium arsenide alloy.

[0080] In technical documents or patents, it is often written as "aluminum gallium arsenide" with subscripts to indicate the composition, for example: Al0.9Ga0.1As (aluminum 0.9 gallium 0.1 arsenide).

[0081] Next, hydrodynamic suspension is performed on the gas-phase lifted wafer through a gradient laminar gas field. A porous ceramic flow equalizer plate is set in the cavity, and laminar nitrogen is introduced. The flow rate shows a linear gradient distribution from the center to the edge of the wafer (0.3 m / s at the center and 1.1 m / s at the edge), forming a stable shear flow field. The suspended fluorinated residue particles are under the combined action of Stokes drag and Bernoulli lift, maintaining a dynamic balance on the gas film, neither settling nor splashing, thus obtaining a suspended-phase wafer. This laminar flow design avoids re-deposition caused by turbulence, especially ensuring the cleaning consistency in the high aspect ratio structure area.

[0082] On this basis, directional flow field removal is performed based on the suspended-phase wafer. An annular air extraction port is opened at the edge of the cavity, and combined with central air intake, a radial outward net flow field vector is constructed. The suspended particles are guided to the edge of the wafer along the main flow and are sucked into a particle trap (a polytetrafluoroethylene filter membrane with a pore size of 0.01 μm) through a negative pressure pipeline ( 20 kPa), completing physical removal, and finally obtaining a free residue wafer. The entire removal process is completed within 1.2 seconds, ensuring that there is no retention of sublimation products.

[0083] It should be noted that the above steps have a strict temporal coupling relationship: momentum collisions trigger desorption, and after desorption, the residue immediately undergoes in-situ sublimation caused by temperature rise. The sublimated gas itself constitutes the initial lifting medium, and then the external laminar flow field takes over to achieve stable suspension and directional transport. For example, in an 850 nm VCSEL array fabricated on a 6-inch GaAs substrate, the mesa spacing is only 1.5 μm. Traditional N2 purging is prone to causing bridging residues, while this solution improves the residue removal rate to over 99.6% through precise impaction of ultracold particles and subsequent gas-phase lifting in synergy.

[0084] In this embodiment, the above-mentioned scheme achieves non-contact and non-damaging removal of particles on the surface of fluorinated residue wafers through a three-stage relay mechanism of pulse momentum injection, temperature-controlled phase change expansion and gradient laminar flow transport. This not only avoids damage to the high-aluminum epitaxial layer caused by mechanical scraping, but also completely solves the problem of particle retention in deep submicron structures, significantly improving the surface cleanliness of optoelectronic devices and the reliability of subsequent packaging.

[0085] In a specific embodiment, the step of rinsing the free residue wafer with deionized water to obtain a glue-free target wafer includes: The free residue wafer was subjected to acoustic flow boundary layer penetration by mega-sonic deionized water to obtain a salt-dissolved wafer. Based on the salt-dissolved wafer, transient cavitation microjet impact is performed to obtain an ion-desorbed wafer; The ion-desorbed wafer is subjected to surface tension gradient drainage by gradient alcohol vapor to obtain an alcohol-water replaced wafer. Based on the alcohol-water replacement wafer, supercritical fluid phase change drying is performed to obtain a glue-free target wafer.

[0086] Specifically, in this embodiment, the deionized water rinsing operation based on the free residue wafer first employs megasonic deionized water to achieve acoustic flow boundary layer penetration. The deionized water used has a resistivity of not less than 18.2 MΩ·cm and is uniformly covered on the wafer surface at a flow rate of 0.8 L / min through a quartz spray head. Simultaneously, megasonic waves with a frequency of 950 kHz and a power density of 3.5 W / cm² are applied. At this frequency, the wavelength of the acoustic wave (approximately 1.6 μm) is comparable to the size of the residual particles between VCSEL mesas, which can excite a high-frequency oscillating flow field at the solid-liquid interface, effectively destroying the Stokes boundary layer (approximately 200 nm thick). This causes the metal fluorides (such as NaF, AlF3) and trace amounts of borate in the residual fluorination byproducts to rapidly dissolve in the water, forming a salt-dissolving wafer. This process lasts for 45 seconds, with the temperature controlled at 22±1℃ to prevent thermal stress damage to the Al0.9Ga0.1As epitaxial layer.

[0087] Subsequently, transient cavitation microjets are applied to the salt-dissolved wafer. Megasonic waves induce microbubble nucleation under localized negative pressure, while positive pressure causes asymmetric collapse within nanoseconds, generating microjets with velocities up to 120 m / s. These microjets impact the wafer surface perpendicularly, particularly targeting ion adsorption sites at the bottom and sidewalls of the trenches, transferring hydrated metal ions (such as [Al(H₂O)₆]³) through momentum transfer. + [Na(H2O)4] + The cavitation intensity is precisely controlled by adjusting the acoustic pressure amplitude (peak value 0.9 MPa) to avoid excessive erosion of the GaAs lattice.

[0088] Next, a surface tension gradient drainage process is implemented on the ion-desorbed wafer using gradient alcohol vapor. Isopropanol (IPA) saturated vapor is introduced into the chamber, with its concentration increasing linearly from the center to the edge radially of the wafer (30 vol% at the center, 95 vol% at the edge), creating a surface tension gradient (γ decreases from 72 mN / m to 21 mN / m). This gradient drives the residual water film to spontaneously spread and drain towards the low surface energy region (i.e., the high IPA concentration region), achieving a gradual replacement of the aqueous phase with the alcohol phase, resulting in an alcohol-water displacement wafer. This process is performed at 40°C for 60 seconds, utilizing the Marangoni effect to eliminate water stains and avoid drying spots.

[0089] Finally, the alcohol-water displacement wafer was dried using supercritical fluid phase change drying. After sealing the chamber, liquid CO2 was injected, reaching a supercritical state at 31.1°C and 7.38 MPa. This state was maintained for 10 minutes to allow IPA to completely dissolve in the supercritical CO2 phase. Subsequently, the pressure was slowly released (at a rate of 0.5 MPa / min), allowing the system to bypass the gas-liquid coexistence zone and directly transition from the supercritical phase to the gas phase without abrupt changes in surface tension. This avoided structural collapse or particle redeposition caused by capillary forces, ultimately yielding a glue-free target wafer. After drying, the surface contact angle stabilized at 78°, indicating the absence of organic or ionic residues.

[0090] In this embodiment, the above-mentioned scheme achieves thorough cleaning and non-destructive drying of free residue wafers through the synergistic effect of megasonic mass transfer enhancement, cavitation micro-jet physical stripping, Marangoni drainage and supercritical drying. It not only efficiently removes soluble salts and adsorbed ions introduced by the fluorination process, but also eliminates the edge residue problem caused by traditional spin drying, significantly improving the surface cleanliness and electro-optic performance consistency of VCSEL devices.

[0091] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention. It should be noted that the information interaction, execution process, etc. between the above devices / units are based on the same concept as the method embodiments of this application. Their specific functions and technical effects can be found in the embodiment section of the control device, and will not be repeated here.

[0092] Please see Figure 2 , Figure 2 This is a schematic diagram of the framework of an embodiment of the VCSEL chip wafer resist removal apparatus of this application. Figure 2 As shown, the VCSEL chip wafer resist removal device includes a swelling module 1, which is used to penetrate and swell the VCSEL chip wafer to be resisted to obtain a swollen colloidal wafer. The stripping module 2 is used to perform pressure-reducing phase change stripping based on the swollen colloidal wafer to obtain the initial stripped wafer; Bond breaking module 3 is used to perform photochemical bond breaking on the initially peeled wafer using a tunable ultraviolet light source to obtain a bond-broken residual adhesive wafer; Replacement module 4 is used to perform vapor-phase fluorination replacement based on the broken bond residual glue wafer to obtain fluorinated residue wafer; The purging module 5 is used to perform momentum transfer purging on the fluorinated residue wafer to obtain a free residue wafer; The rinsing module 6 is used to rinse the free residue wafer with deionized water to obtain a glue-free target wafer.

[0093] The above module is used to perform the steps of the VCSEL chip wafer resist removal method.

Claims

1. A method for removing adhesive from a VCSEL chip wafer, characterized in that, Includes the following steps: The VCSEL chip wafer to be de-adhesive is permeated and swollen to obtain a swollen colloidal wafer; Based on the swollen colloidal wafer, a pressure-reducing phase change peeling is performed to obtain the initial peeled wafer; Photochemical bond breaking is performed on the initially stripped wafer using a tunable ultraviolet light source to obtain a bond-broken residual adhesive wafer. Based on the bond-broken residual glue wafer, a vapor-phase fluorination replacement was performed to obtain a fluorinated residue wafer; The fluorinated residue wafer is subjected to momentum transfer purging to obtain a free residue wafer; The wafer with the free residue is rinsed with deionized water to obtain a glue-free target wafer.

2. The method for removing adhesive from VCSEL chip wafers according to claim 1, characterized in that, The VCSEL chip wafer to be de-adhesive is subjected to infiltration swelling to obtain a swollen colloidal wafer, comprising: Deep trench microfluidic permeation of the VCSEL chip wafer to be de-adhesive is performed using a gradient pressure supercritical fluid to obtain a fluid-saturated wafer. Based on the fluid-saturated wafer, the molecular pores of the phase change medium are filled to obtain the phase change pre-set wafer; The phase change pre-formed wafer is decoupled by hydrogen bonds in the residual adhesive crosslinking network through a megaacoustic frequency field to obtain a network destructured wafer. Polymer free volume expansion is performed on the aforementioned mesh-structured wafer to obtain a swollen colloidal wafer.

3. The method for removing adhesive from VCSEL chip wafers according to claim 1, characterized in that, The step of performing a depressurized phase change peeling based on the swollen colloidal wafer to obtain a first peeled wafer includes: A phase change vaporization wafer is obtained by step-pulse decompression of the swollen colloidal wafer through an isentropic expansion chamber, and an internal stress release is performed on the phase change vaporization wafer to obtain a bulk tearing wafer. The bulk phase torn wafer is subjected to high-frequency shear oscillation to obtain an interface decoupled wafer, and the bottom adhesion bond is broken based on the interface decoupled wafer to obtain a bottom wall desorbed wafer. The bottom-wall desorbed wafer is swept by a supersonic airflow to obtain a fragmented wafer, and gas-solid two-phase separation is performed based on the fragmented wafer to obtain a preliminary desorbed wafer.

4. The method for removing adhesive from VCSEL chip wafers according to claim 1, characterized in that, The process of photochemically breaking bonds in the initially peeled wafer using a tunable ultraviolet light source to obtain a bond-broken residual adhesive wafer includes: A photon-excited wafer is obtained by injecting photon energy in a characteristic frequency band into the initially stripped wafer using a tunable ultraviolet light source. Based on the photon-excited wafer, multiphoton resonance absorption is performed to obtain a high-energy state residual adhesive wafer; The high-energy state residual glue wafer is subjected to non-thermal relaxation bond breaking using a nanosecond pulse modulator to obtain a chain-broken residual glue wafer, and a three-dimensional cross-linked network depolymerization is performed based on the chain-broken residual glue wafer to obtain a short-chain residue wafer. The short-chain residue wafer is subjected to free radical quenching by a low-temperature inert gas flow to obtain a quenched residue wafer; Spatial steric rearrangement is performed on the quenched residue wafer to obtain a bond-broken residue wafer.

5. The method for removing adhesive from VCSEL chip wafers according to claim 4, characterized in that, The process of depolymerizing the three-dimensional cross-linked network based on the broken-chain residue wafer to obtain a short-chain residue wafer includes: The broken-chain residual adhesive wafer is subjected to high-frequency oscillation of molecular chain segments to obtain a physically untangled wafer, and local thermal stress is induced based on the physically untangled wafer to obtain a network relaxation wafer; By performing cross-linking node solvation intercalation on the network relaxation wafer using a supercritical polar fluid, a dipole-effect wafer is obtained. Based on the dipole-effect wafer, the network pores are expanded and enlarged to obtain a swollen and expanded wafer. The swollen and expanded wafer is injected with highly reactive oxygen free radicals in a gas-phase ozone field to obtain a targeted oxidation wafer, and the cross-linked bonds are broken and sheared in situ based on the targeted oxidation wafer to obtain a short-chain residue wafer.

6. The method for removing adhesive from VCSEL chip wafers according to claim 1, characterized in that, The process of performing vapor-phase fluorination replacement based on the bond-broken residual adhesive wafer to obtain a fluorinated residue wafer includes: The broken bond residual glue wafer is targeted molecularly adsorbed by a gas phase molecular diffusion source to obtain a fluorine source attached wafer, and surface chemical coordination is performed based on the fluorine source attached wafer to obtain a reaction precursor wafer. The precursor wafer is selectively fluorinated and substituted using a stepped thermal field generator to obtain a fluorocarbon conversion wafer, and polar groups are eliminated based on the fluorocarbon conversion wafer to obtain a low surface energy wafer. The low surface energy wafer is subjected to isothermal sublimation phase transition by a differential pressure desorption controller to obtain an in-situ desorbed wafer, and gas-solid phase separation is performed based on the in-situ desorbed wafer to obtain a fluorinated residue wafer.

7. The method for removing adhesive from VCSEL chip wafers according to claim 6, characterized in that, The process of eliminating polar groups based on the fluorocarbon conversion wafer to obtain a low surface energy wafer includes: The fluorocarbon conversion wafer is activated by polar bond complexation using a gas-phase Lewis acid source to obtain a complex activated wafer, and then protonation fracture desorption is performed on the complex activated wafer to obtain a polar decoupled wafer. The polar decoupled wafer is passivated in situ by dangling bonds using a pulsed fluorine radical beam to obtain a fluorine-based grafted wafer, and then the fluorine-carbon chain segments are spatially rolled up based on the fluorine-based grafted wafer to obtain a hydrophobic shielding wafer. The hydrophobic shielding wafer is weakened by the van der Waals forces at the interface to obtain an interface-slip wafer, and the surface free energy is minimized based on the interface-slip wafer to obtain a low surface energy wafer.

8. The method for removing adhesive from VCSEL chip wafers according to claim 1, characterized in that, The step of performing momentum transfer purging on the fluorinated residue wafer to obtain a free residue wafer includes: The fluorinated residue wafer is subjected to momentum transfer collisions via pulsed ultracold aerosols to obtain collision desorption wafers. Based on the collision desorption wafer, in-situ sublimation expansion is performed to obtain a vapor-supported wafer; The gas-phase lifted wafer is hydrodynamically suspended by a gradient laminar flow field to obtain a suspended phase wafer, and a directional flow field is used to remove the free residue wafer based on the suspended phase wafer.

9. The method for removing adhesive from a VCSEL chip wafer according to claim 1, characterized in that, The process of rinsing the free residue wafer with deionized water to obtain a glue-free target wafer includes: The free residue wafer was subjected to acoustic flow boundary layer penetration by mega-sonic deionized water to obtain a salt-dissolved wafer. Based on the salt-dissolved wafer, transient cavitation microjet impact is performed to obtain an ion-desorbed wafer; The ion-desorbed wafer is subjected to surface tension gradient drainage by gradient alcohol vapor to obtain an alcohol-water replaced wafer. Based on the alcohol-water replacement wafer, supercritical fluid phase change drying is performed to obtain a glue-free target wafer.

10. A VCSEL chip wafer resist removal system, characterized in that, include: The swelling module is used to permeate and swell the VCSEL chip wafers to be de-adhesive-removed to obtain swollen colloidal wafers. The stripping module is used to perform pressure-reducing phase change stripping on the swollen colloidal wafer to obtain a preliminary stripped wafer. The bond-breaking module is used to perform photochemical bond breaking on the initially peeled wafer using a tunable ultraviolet light source to obtain a bond-broken residual adhesive wafer. The replacement module is used to perform vapor-phase fluorination replacement based on the bond-broken residual adhesive wafer to obtain a fluorinated residue wafer; The purging module is used to perform momentum transfer purging on the fluorinated residue wafer to obtain a free residue wafer. The rinsing module is used to rinse the free residue wafer with deionized water to obtain a glue-free target wafer.

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