A micro-integrated high-precision laser package substrate
Patent Information
- Application Number
- CN202521361387.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-01
- Publication Date
- 2026-09-25
- Estimated Expiration
- 2035-07-01
Smart Images
Figure CN224804440U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of high-precision laser packaging substrate technology, specifically a micro-integrated high-precision laser packaging substrate. Background Technology
[0002] High-precision semiconductor laser packaging devices based on platinum thin-film temperature resistance heat sinks, more specifically, involve the technology of directly fabricating platinum thin-film resistors on the surface of the COC (Chip-on-Carrier) heat sink of the laser chip and integrating them on the same ceramic substrate to achieve an integrated design of temperature sensing and heat dissipation functions. This is suitable for semiconductor laser packaging applications with strict requirements for miniaturization and high stability, such as optical communication and quantum precision measurement.
[0003] Traditional laser packaging relies on PTC or NTC thermistors for temperature control, but this method suffers from problems such as large size, slow response speed, and incompatibility with integrated circuit manufacturing processes. The main issues are concentrated in the following aspects: (1) Size and integration conflict: Discrete thermistors are relatively large, taking up space in miniaturized packages. For example, a TO-46 package requires additional thermistor placement, which complicates the heat dissipation path and increases the number of package layers. Figure 1 A schematic diagram of a traditional PTC / NTC thermistor package structure (discrete component layout, heat sink and sensor are separate) is shown; (2) Insufficient response speed and accuracy: PTC / NTC thermistors have low TCR (NTC is generally -2%~-6% / ℃, PTC is generally 1%~5% / ℃), and the response time is >50 ms, which is difficult to meet the real-time monitoring requirements of nanosecond-level temperature fluctuations in quantum measurement, such as Figure 2 The temperature response curves of platinum resistance thermometers and traditional thermistors are shown in comparison.
[0004] (3) Poor process compatibility: Traditional thermistors rely on ceramic sintering or doping processes, which are difficult to be compatible with thin film deposition and photolithography technologies of integrated circuits, resulting in complex production processes and high costs.
[0005] (4) Heat dissipation and reliability issues: With the development of laser miniaturization and integration, the power density after integration has been significantly improved and the heat generation is concentrated. However, the traditional separate design of heat sink and thermistor introduces additional thermal resistance, which can easily lead to solder joint failure or performance drift (such as NTC resistor annual drift rate > 1%) after long-term use. Utility Model Content
[0006] The technical problem to be solved by this utility model is to overcome the existing defects and provide a micro-integrated high-precision laser packaging substrate. By using nanoscale platinum thin film technology (thickness ≤200 nm) and micron-level patterning design, the sensor size is reduced, which can meet the packaging needs of the development of laser miniaturization and integration and effectively solve the problems in the background technology.
[0007] To achieve the above objectives, the present invention provides the following technical solution: a micro-integrated high-precision laser packaging substrate, comprising an aluminum nitride ceramic substrate, a platinum metal thin film layer disposed on the upper side of the aluminum nitride ceramic substrate, an alumina deposition layer disposed on the upper side of the aluminum nitride ceramic substrate and the platinum metal thin film layer, and a heat sink metal film layer disposed on the upper side of the alumina deposition layer.
[0008] Furthermore, a metal layer is disposed on the underside of the aluminum nitride ceramic substrate, and the metal layer is processed in the same way as the heat sink metal film layer.
[0009] Furthermore, the structural layer metals of the metal layer and the heat sink metal film layer are Ti / Cu / Ni / Au.
[0010] Furthermore, the thickness of the platinum metal thin film layer is ≤200 nm.
[0011] The packaging steps are as follows: Step 1: Ceramic substrate pretreatment (1) Aluminum nitride (AlN) ceramic material is used, with a thermal conductivity of 220 W / m·K and a substrate size of 20 mm × 10 mm × 1 mm; (2) Rough polishing: Use a diamond grinding wheel (120# grit), grinding pressure 0.5 MPa, rotation speed 500 rpm, double-sided grinding to a thickness of 0.7 mm to remove larger scratches and particles from the surface. Use a contact surface profilometer to detect the surface roughness Ra, which should be Ra < 500 nm; (3) Fine polishing: Replace with a diamond grinding wheel (600# grit), grind at a pressure of 0.2 MPa and a speed of 300 rpm, and grind both sides to a thickness of about 0.52 mm to further improve the surface smoothness. Check the surface roughness Ra again, which should be Ra < 100 nm. (4) CMP polishing: Chemical mechanical polishing (CMP) equipment was used. The polishing slurry was SiO2 colloid (particle size 20 nm), the polishing pressure was 0.1 MPa, the rotation speed was 200 rpm, and the single side was polished to a thickness of 0.5±0.01 mm. The surface roughness Ra after polishing was <10 nm. The detection equipment was a non-contact white light interferometer. (5) Cleaning after polishing: Acetone cleaning: Immerse the ground ceramic substrate in acetone and ultrasonically clean for 10 minutes at an ultrasonic power of 40 kHz and a cleaning temperature of 25°C to remove surface organic matter and grease; IPA cleaning: Transfer to isopropanol (IPA) and ultrasonically clean for 10 minutes at an ultrasonic power of 40 kHz and a cleaning temperature of 25°C to further remove residual particles on the surface; DI water cleaning: Finally, rinse with deionized water (DI water) to ensure no residual cleaning solution; use a nitrogen gun to blow dry to ensure no water stains on the surface.
[0012] Step 2: Platinum (Pt) thin film deposition (1) Plasma activation: Plasma activation treatment was carried out in an Ar atmosphere with a power of 200 W and a treatment time of 5 minutes to enhance surface activity; (2) Fixture installation: Fix the pretreated AlN ceramic substrate onto the fixture of the ULVAC film-type magnetron sputtering equipment, ensuring that the substrate surface is flat and parallel to the sputtering target; Vacuum evacuation: Start the vacuum system of the magnetron sputtering equipment to reduce the gas pressure in the chamber to below 5×10-6 Torr, so as to ensure that the sputtering process is carried out under high vacuum conditions, thereby reducing the mixing of impurities; Pre-sputtering cleaning: Introduce high-purity argon gas (purity ≥99.99%) and set the gas flow rate to 50 sccm. Set the sputtering power to 150 W and perform pre-cleaning on the sputtering chamber to remove oxides and impurities from the inner wall of the chamber and the surface of the target. The cleaning process lasts for 10 minutes; (3) Pt thin film deposition: Maintain argon flow rate at 50 sccm, adjust sputtering pressure to 5×10-6 Torr, and set substrate temperature to 300℃ to improve the crystal quality and adhesion strength of the Pt thin film to the substrate. Set sputtering power of Pt target to 150 W and begin Pt thin film deposition. Use crystal oscillator to monitor film thickness in real time to ensure that the deposited Pt film thickness reaches 200 nm and the thickness error is controlled within ±5 nm. (4) Post-treatment high-temperature annealing: After deposition, the sputtering power supply is turned off, the atmospheric pressure in the chamber is slowly restored, and the sputtered AlN ceramic substrate is removed. High-temperature annealing is performed using a rapid thermal annealing (RTP) system, with the optimal annealing temperature range between 500℃ and 800℃, and the process time maintained between 30 and 90 minutes. The sheet resistance after annealing is in the range of 0.8-1.5Ω / sq, and the TCR (temperature coefficient) is significantly improved after annealing, exceeding 3500 ppm / ℃.
[0013] Step 3: Platinum resistance lithography patterning (1) Spin coating of photoresist: positive photoresist (AZ 5214) was used. A two-stage spin coating process was adopted. The spin coating speed in the first stage was set to 600 rpm and the spin coating time was 5 seconds. The spin coating speed in the second stage was set to 3000 rpm and the spin coating time was 30 seconds to obtain a photoresist thickness of 1.5 μm. (2) Pre-baking: Heat to 90°C using a hot plate for 60 seconds to ensure the photoresist is fully cured; (3) Ultraviolet exposure: Exposure is performed using a SUSS lithography machine with a mask alignment system. The exposure energy is 200 mJ / cm to form a platinum resistance pattern (line width 10 μm, spacing 5 μm). (4) Development: Use 2.38% TMAH developer for 40 seconds and maintain the temperature at 22°C to remove the photoresist in the exposed area; (5) Cleaning after development: Oxygen plasma cleaning technology is used to remove residual photoresist. The oxygen volume flow rate is set to 50 sccm, the power is 80 W, and the processing time is 2 minutes.
[0014] Step 4: Platinum resistance etching (1) Ion beam etching (IBE) technology was used to etch the Pt thin film using an “Oxford Plasmalab 80+” model instrument. The main etching gas was argon (Ar), with a gas flow rate of 30 sccm, a vacuum degree of 0.5 Pa, a power of 400 W, and an etching rate of about 10 nm / min. (2) Wet removal of photoresist: Use NMP (N-methylpyrrolidone) solution, soak at 60°C for 30 minutes, then rinse with deionized water and dry with nitrogen gas; (3) Cleaning: Acetone cleaning: Immerse the ground ceramic substrate in acetone and ultrasonically clean for 10 minutes at an ultrasonic power of 40 kHz and a cleaning temperature of 25°C to remove surface organic matter and grease; IPA cleaning: Transfer to isopropanol (IPA) and ultrasonically clean for 10 minutes at an ultrasonic power of 40 kHz and a cleaning temperature of 25°C to further remove residual particles on the surface; DI water cleaning: Finally, rinse with deionized water (DI water) to ensure no residual cleaning solution; use a nitrogen gun to blow dry to ensure no water stains on the surface.
[0015] Step 5: Deposit a protective layer (alumina deposition layer) (1) Substrate pretreatment: Oxygen plasma cleaning technology was used to remove residual photoresist. The oxygen volume flow rate was set to 50 sccm, the power was 100 W, and the treatment time was 5 minutes.
[0016] (2) ALD deposition of alumina film: A Savannah 10 atomic layer deposition (ALD) equipment was used, and the thermal deposition method was employed. Trimethylaluminum (TMA) precursor was used as the aluminum source, and water vapor (H2O) was used as the oxygen source precursor. The deposition temperature was set at 200℃, and the vacuum level was maintained at 5×10⁻⁶ Torr. The pulse process parameters were as follows: TMA was introduced at a flow rate of 10 sccm, with a pulse duration of 2 seconds, followed by purging with nitrogen at a flow rate of 100 sccm for 5 seconds. H₂O was then introduced at the same flow rate of 10 sccm, with a pulse duration of 2 seconds. Nitrogen purging was repeated again at a flow rate of 100 sccm for 5 seconds. This process was repeated 100 times, resulting in a film thickness of approximately 10 nm and a growth rate of approximately 0.1 nm per cycle.
[0017] Step 6: Preparation of the front metal film layer of the COC heat sink substrate (preparation of the heat sink metal film layer) (1) Substrate cleaning: Immersion: Immerse the AlN ceramic substrate in anhydrous ethanol for 120 minutes to remove organic matter and particles from the surface; place the substrate in acetone, IPA solution and deionized water in sequence for ultrasonic cleaning for 10 minutes to remove residual particles and organic matter from the surface; blow dry with high-purity nitrogen to ensure that there are no water stains on the substrate surface. (2) Front metallization structure: Ti adhesion transition layer was deposited using magnetron sputtering equipment at room temperature, sputtering power DC400W, Ar gas flow rate 30 sccm, vacuum degree: 5×10-6 Torr, deposition thickness 0.1±0.02 μm; (3) Thick film photolithography patterning: Use SU-8 2035 photoresist, initial spin coating speed 600 rpm, spin coating time 10 seconds, final spin coating speed 1500 rpm, spin coating time 30 seconds, pre-baking at 65℃ for 5~10 minutes, then at 95℃ for 30~60 minutes, and naturally cool to room temperature to avoid sudden cooling that could cause warping or desorption of the photoresist layer; UV exposure at 365nm wavelength, exposure dose range 200-400 mJ / cm², post-baking at 95℃ for 5~15 minutes to promote cross-linking reaction and reduce residue after development; use PGMEA developer for about 5~10 minutes, which can be combined with 35W ultrasonic assistance, and after development, rinse with isopropyl alcohol (IPA) and dry with nitrogen to avoid deformation or contamination of the photoresist mold.
[0018] (4) Preparation of Cu thermal conductive layer: The thickness of the electroplated copper film is 75±10 μm, the concentration of CuSO4 in the main components of the electroplating solution is 200 g / L, the concentration of H2SO4 is 50 g / L, the current density is set to 2 A / dm, and the electroplating time is 3 hours. (5) Preparation of Ni barrier layer: The Ni film deposition thickness is 3±1 μm, the concentration of NiSO4, the main component of the electroplating solution is 250g / L, the current density is 1 A / dm², and the electroplating time is 30 minutes. (6) Preparation of Au protective layer: The thickness of the electroplated Au film is 1.2±0.3 μm, the composition of the plating solution is: KAu(CN)2 concentration 5g / L, pH value 4.5, and the plating solution temperature is 60℃; (7) Resin removal and cleaning process: Plasma resist removal: O2 / CF4 plasma etching is used to remove SU-8 photoresist, oxygen volume flow rate is 25 sccm, RF power is 200W, gas pressure is 40 mTorr, and etching time is 10 minutes; Wet resist removal: The substrate is immersed in Remover PG at 50-80℃ to remove most of the photoresist, then rinsed with IPA solvent, and finally rinsed with deionized water and dried with nitrogen.
[0019] Step 7: Preparation of the front AuSn soldering area (1) Substrate cleaning: Immersion: Immerse the AlN ceramic substrate in anhydrous ethanol for 120 minutes to remove organic matter and particles from the surface; place the substrate in acetone, IPA solution and deionized water in sequence for ultrasonic cleaning for 10 minutes to remove residual particles and organic matter from the surface; blow dry with high-purity nitrogen to ensure that there are no water stains on the substrate surface. (2) AuSn region photomask: AZ4620 photoresist was used. The initial spin coating speed was 600 rpm and the spin coating time was 5 seconds. The final spin coating speed was 2500 rpm and the spin coating time was 30 seconds. The pre-baking temperature was 90℃ and the baking time was 2~3 minutes. Then the temperature was 100℃ and the baking time was 3~5 minutes. UV exposure was performed at a wavelength of 365 nm and an exposure dose range of 200-300 mJ / cm². The post-baking temperature was 110℃ and the baking time was 1~2 minutes to promote the crosslinking reaction and reduce the residue after development. The development was performed using 25% TMAH developer in 8:1 deionized water for about 1~3 minutes. After development, the solution was immediately rinsed with deionized water for 30 seconds and dried with nitrogen to reduce the residue.
[0020] (3) AuSn alloy layer coating: Using an electron beam evaporation coating equipment, Au and Sn are mixed at a mass ratio of 80:20. The resulting alloy target is placed in the evaporation source, and the background vacuum in the vacuum chamber is evacuated to below 5×10-4 Pa. The evaporation rate of the AuSn alloy target is controlled to maintain it at 0.1-0.3 nm / s to ensure the uniformity and density of the film. The substrate temperature is optimally controlled within the range of 150-200℃ to improve the adhesion between the film and the substrate and the crystal quality of the film. The coated substrate is then annealed in an inert gas atmosphere such as nitrogen or argon at a temperature of 200-300℃ for 30-60 minutes to eliminate internal stress in the film and improve its performance.
[0021] (4) Lift-off photoresist removal: Wet photoresist removal, the substrate is immersed in Remover PG at 50-80℃ to remove most of the photoresist, then rinsed with IPA solvent, and finally rinsed with deionized water and dried with nitrogen; Oxygen plasma ashing, O2 plasma etching is used to remove AZ4620 photoresist, oxygen volume flow rate 25 sccm, power 85 W, gas pressure 40 mTorr, etching time 10 minutes; after wet cleaning, it is dried.
[0022] Step 8: Metallization of the back side (1) The same Ti / Cu / Ni / Au structure as the front side is adopted to ensure a symmetrical heat dissipation path.
[0023] Compared with the prior art, the beneficial effects of this utility model are: 1. By using nanoscale platinum thin film technology (thickness ≤200 nm) and micron-level patterning design, the sensor size is reduced to meet the packaging requirements of laser miniaturization and integration. 2. By utilizing the ultra-high temperature coefficient of resistance (TCR) and linearity of platinum resistance thermometers, a temperature detection accuracy of ±0.01℃ and a response speed of less than 10 ms are achieved, thus overcoming the performance bottlenecks of insufficient temperature measurement accuracy and response of traditional thermistors.
[0024] 3. It adopts micro-nano process fabrication methods such as sputtering and photolithography, and is a planar process fabrication method, which is fully compatible with the existing integrated circuit process fabrication methods, simplifies the production process, reduces the fabrication cost, and is suitable for mass production; 4. By reducing the thermal interface layer through integrated design, heat dissipation efficiency and long-term device reliability are improved. Attached Figure Description
[0025] Figure 1 This is a schematic diagram of a traditional PTC / NTC thermistor packaging structure (discrete component layout, heat sink and sensor are separate). Figure 2 This is a schematic diagram of the structure of the platinum thin film resistor integrated into the COC heat sink in this utility model (integrated design, micron-level resistor pattern). Figure 3 Illustration of miniaturized integration of a laser butterfly package structure (effect on volume and weight optimization). Figure 4 Flowchart of integrated fabrication process for thermistors and COC heat sinks; Figure 5 A comparison of the temperature response curves of platinum resistance thermometers and traditional thermistors (highlighting high TCR and fast response characteristics). Figure 6 This is a side sectional view of the substrate of this utility model.
[0026] In the figure: 1. Aluminum nitride ceramic substrate; 2. Platinum metal thin film layer; 3. Alumina deposition layer; 4. Heat sink metal film layer; 5. Metal layer. Detailed Implementation
[0027] Please see Figure 1-6 This embodiment provides a technical solution: a micro-integrated high-precision laser packaging substrate, including an aluminum nitride ceramic substrate 1, a platinum metal thin film layer 2 disposed on the upper side of the aluminum nitride ceramic substrate 1, an aluminum oxide deposition layer 3 disposed on the upper side of the aluminum nitride ceramic substrate 1 and the platinum metal thin film layer 2, and a heat sink metal film layer 4 disposed on the upper side of the aluminum oxide deposition layer 3.
[0028] A metal layer 5 is disposed on the lower side of the aluminum nitride ceramic substrate 1, and the metal layer 5 is processed in the same way as the heat-sink metal film layer 4.
[0029] The structural metals of metal layer 5 and heat sink metal film layer 4 are Ti / Cu / Ni / Au.
[0030] The packaging steps are as follows: Step 1: Ceramic substrate pretreatment (1) Aluminum nitride (AlN) ceramic material is used, with a thermal conductivity of 220 W / m·K and a substrate size of 20 mm × 10 mm × 1 mm; (2) Rough polishing: Use a diamond grinding wheel (120# grit), grinding pressure 0.5 MPa, rotation speed 500 rpm, double-sided grinding to a thickness of 0.7 mm to remove larger scratches and particles from the surface. Use a contact surface profilometer to detect the surface roughness Ra, which should be Ra < 500 nm; (3) Fine polishing: Replace with a diamond grinding wheel (600# grit), grind at a pressure of 0.2 MPa and a speed of 300 rpm, and grind both sides to a thickness of about 0.52 mm to further improve the surface smoothness. Check the surface roughness Ra again, which should be Ra < 100 nm. (4) CMP polishing: Chemical mechanical polishing (CMP) equipment was used. The polishing slurry was SiO2 colloid (particle size 20 nm), the polishing pressure was 0.1 MPa, the rotation speed was 200 rpm, and the single side was polished to a thickness of 0.5±0.01 mm. The surface roughness Ra after polishing was <10 nm. The detection equipment was a non-contact white light interferometer. (5) Cleaning after polishing: Acetone cleaning: Immerse the ground ceramic substrate in acetone and ultrasonically clean for 10 minutes at an ultrasonic power of 40 kHz and a cleaning temperature of 25°C to remove surface organic matter and grease; IPA cleaning: Transfer to isopropanol (IPA) and ultrasonically clean for 10 minutes at an ultrasonic power of 40 kHz and a cleaning temperature of 25°C to further remove residual particles on the surface; DI water cleaning: Finally, rinse with deionized water (DI water) to ensure no residual cleaning solution; use a nitrogen gun to blow dry to ensure no water stains on the surface.
[0031] Step 2: Platinum Metal Thin Film Deposition (1) Plasma activation: Plasma activation treatment was carried out in an Ar atmosphere with a power of 200 W and a treatment time of 5 minutes to enhance surface activity; (2) Fixture installation: Fix the pretreated AlN ceramic substrate onto the fixture of the ULVAC film-type magnetron sputtering equipment, ensuring that the substrate surface is flat and parallel to the sputtering target; Vacuum evacuation: Start the vacuum system of the magnetron sputtering equipment to reduce the gas pressure in the chamber to below 5×10-6 Torr, so as to ensure that the sputtering process is carried out under high vacuum conditions, thereby reducing the mixing of impurities; Pre-sputtering cleaning: Introduce high-purity argon gas (purity ≥99.99%) and set the gas flow rate to 50 sccm. Set the sputtering power to 150 W and perform pre-cleaning on the sputtering chamber to remove oxides and impurities from the inner wall of the chamber and the surface of the target. The cleaning process lasts for 10 minutes; (3) Pt thin film deposition: Maintain argon flow rate at 50 sccm, adjust sputtering pressure to 5×10-6 Torr, and set substrate temperature to 300℃ to improve the crystal quality and adhesion strength of the Pt thin film to the substrate. Set sputtering power of Pt target to 150 W and begin Pt thin film deposition. Use crystal oscillator to monitor film thickness in real time to ensure that the deposited Pt film thickness reaches 200 nm and the thickness error is controlled within ±5 nm. (4) Post-treatment high-temperature annealing: After deposition, the sputtering power supply is turned off, the atmospheric pressure in the chamber is slowly restored, and the sputtered AlN ceramic substrate is removed. High-temperature annealing is performed using a rapid thermal annealing (RTP) system, with the optimal annealing temperature range between 500℃ and 800℃, and the process time maintained between 30 and 90 minutes. The sheet resistance after annealing is in the range of 0.8-1.5Ω / sq, and the TCR (temperature coefficient) is significantly improved after annealing, exceeding 3500 ppm / ℃.
[0032] Step 3: Platinum resistance lithography patterning (1) Spin coating of photoresist: positive photoresist (AZ 5214) was used. A two-stage spin coating process was adopted. The spin coating speed in the first stage was set to 600 rpm and the spin coating time was 5 seconds. The spin coating speed in the second stage was set to 3000 rpm and the spin coating time was 30 seconds to obtain a photoresist thickness of 1.5 μm. (2) Pre-baking: Heat to 90°C using a hot plate for 60 seconds to ensure the photoresist is fully cured; (3) Ultraviolet exposure: Exposure is performed using a SUSS lithography machine with a mask alignment system. The exposure energy is 200 mJ / cm2 to form a platinum resistance pattern (line width 10 μm, spacing 5 μm). (4) Development: Use 2.38% TMAH developer for 40 seconds and maintain the temperature at 22°C to remove the photoresist in the exposed area; (5) Cleaning after development: Oxygen plasma cleaning technology is used to remove residual photoresist. The oxygen volume flow rate is set to 50 sccm, the power is 80 W, and the processing time is 2 minutes.
[0033] Step 4: Platinum resistance etching (1) Ion beam etching (IBE) technology was used to etch the Pt thin film using an “Oxford Plasmalab 80+” model instrument. The main etching gas was argon (Ar), with a gas flow rate of 30 sccm, a vacuum degree of 0.5 Pa, a power of 400 W, and an etching rate of about 10 nm / min. (2) Wet removal of photoresist: Use NMP (N-methylpyrrolidone) solution, soak at 60°C for 30 minutes, then rinse with deionized water and dry with nitrogen gas; (3) Cleaning: Acetone cleaning: Immerse the ground ceramic substrate in acetone and ultrasonically clean for 10 minutes at an ultrasonic power of 40 kHz and a cleaning temperature of 25°C to remove surface organic matter and grease; IPA cleaning: Transfer to isopropanol (IPA) and ultrasonically clean for 10 minutes at an ultrasonic power of 40 kHz and a cleaning temperature of 25°C to further remove residual particles on the surface; DI water cleaning: Finally, rinse with deionized water (DI water) to ensure no residual cleaning solution; use a nitrogen gun to blow dry to ensure no water stains on the surface.
[0034] Step 5: Deposit protective layer (1) Substrate pretreatment: Oxygen plasma cleaning technology was used to remove residual photoresist. The oxygen volume flow rate was set to 50 sccm, the power was 100 W, and the treatment time was 5 minutes.
[0035] (2) ALD deposition of alumina film: A Savannah 10 atomic layer deposition (ALD) equipment was used, and the thermal deposition method was employed. Trimethylaluminum precursor was used as the aluminum source, and water vapor was used as the oxygen source precursor. The deposition temperature was set at 200℃, and the vacuum level was maintained at 5×10⁻⁶ Torr. The pulse process parameters were as follows: TMA was introduced at a flow rate of 10 sccm, with a pulse duration of 2 seconds, followed by purging with nitrogen at a flow rate of 100 sccm for 5 seconds. H₂O was then introduced at the same flow rate of 10 sccm, with a pulse duration of 2 seconds. Nitrogen purging was repeated again at a flow rate of 100 sccm for 5 seconds. This process was repeated 100 times, resulting in a film thickness of approximately 10 nm and a growth rate of approximately 0.1 nm per cycle.
[0036] Step 6: Fabrication of the front metal film layer of the COC heat sink substrate (1) Substrate cleaning: Immersion: Immerse the AlN ceramic substrate in anhydrous ethanol for 120 minutes to remove organic matter and particles from the surface; place the substrate in acetone, IPA solution and deionized water in sequence for ultrasonic cleaning for 10 minutes to remove residual particles and organic matter from the surface; blow dry with high-purity nitrogen to ensure that there are no water stains on the substrate surface. (2) Front metallization structure: Ti adhesion transition layer was deposited using magnetron sputtering equipment at room temperature, sputtering power DC400W, Ar gas flow rate 30 sccm, vacuum degree: 5×10-6 Torr, deposition thickness 0.1±0.02 μm; (3) Thick film photolithography patterning: Use SU-8 2035 photoresist, initial spin coating speed 600 rpm, spin coating time 10 seconds, final spin coating speed 1500 rpm, spin coating time 30 seconds, pre-baking at 65℃ for 5~10 minutes, then at 95℃ for 30~60 minutes, and naturally cool to room temperature to avoid sudden cooling that could cause warping or desorption of the photoresist layer; UV exposure at 365nm wavelength, exposure dose range 200-400 mJ / cm², post-baking at 95℃ for 5~15 minutes to promote cross-linking reaction and reduce residue after development; use PGMEA developer for about 5~10 minutes, which can be combined with 35W ultrasonic assistance, and after development, rinse with isopropyl alcohol (IPA) and dry with nitrogen to avoid deformation or contamination of the photoresist mold.
[0037] (4) Preparation of Cu thermal conductive layer: The thickness of the electroplated copper film is 75±10 μm, the concentration of CuSO4 in the main components of the electroplating solution is 200 g / L, the concentration of H2SO4 is 50 g / L, the current density is set to 2 A / dm2, and the electroplating time is 3 hours. (5) Preparation of Ni barrier layer: The Ni film deposition thickness is 3±1 μm, the concentration of NiSO4, the main component of the electroplating solution is 250g / L, the current density is 1 A / dm², and the electroplating time is 30 minutes. (6) Preparation of Au protective layer: The thickness of the electroplated Au film is 1.2±0.3 μm, the composition of the plating solution is: KAu(CN)2 concentration 5g / L, pH value 4.5, and plating solution temperature 60℃; (7) Resin removal and cleaning process: Plasma resist removal: O2 / CF4 plasma etching is used to remove SU-8 photoresist, oxygen volume flow rate is 25 sccm, RF power is 200W, gas pressure is 40 mTorr, and etching time is 10 minutes; Wet resist removal: The substrate is immersed in Remover PG at 50-80℃ to remove most of the photoresist, then rinsed with IPA solvent, and finally rinsed with deionized water and dried with nitrogen.
[0038] Step 7: Preparation of the front AuSn soldering area (1) Substrate cleaning: Immersion: Immerse the AlN ceramic substrate in anhydrous ethanol for 120 minutes to remove organic matter and particles from the surface; place the substrate in acetone, IPA solution and deionized water in sequence for ultrasonic cleaning for 10 minutes to remove residual particles and organic matter from the surface; blow dry with high-purity nitrogen to ensure that there are no water stains on the substrate surface. (2) AuSn region photomask: AZ4620 photoresist was used. The initial spin coating speed was 600 rpm and the spin coating time was 5 seconds. The final spin coating speed was 2500 rpm and the spin coating time was 30 seconds. The pre-baking temperature was 90℃ and the baking time was 2~3 minutes. Then the temperature was 100℃ and the baking time was 3~5 minutes. UV exposure was performed at a wavelength of 365 nm and an exposure dose range of 200-300 mJ / cm2. The post-baking temperature was 110℃ and the baking time was 1~2 minutes to promote the crosslinking reaction and reduce the residue after development. Developing was performed with 25% TMAH developer in 8:1 deionized water for about 1~3 minutes. After development, the surface was immediately rinsed with deionized water for 30 seconds and dried with nitrogen to reduce the residue.
[0039] (3) AuSn alloy layer coating: Using an electron beam evaporation coating equipment, Au and Sn are mixed at a mass ratio of 80:20. The resulting alloy target is placed in the evaporation source, and the background vacuum in the vacuum chamber is evacuated to below 5×10-4 Pa. The evaporation rate of the AuSn alloy target is controlled to maintain it at 0.1-0.3 nm / s to ensure the uniformity and density of the film. The substrate temperature is optimally controlled within the range of 150-200℃ to improve the adhesion between the film and the substrate and the crystal quality of the film. The coated substrate is then annealed in an inert gas atmosphere such as nitrogen or argon at a temperature of 200-300℃ for 30-60 minutes to eliminate internal stress in the film and improve its performance.
[0040] (4) Lift-off photoresist removal: Wet photoresist removal, the substrate is immersed in Remover PG at 50-80℃ to remove most of the photoresist, then rinsed with IPA solvent, and finally rinsed with deionized water and dried with nitrogen; Oxygen plasma ashing, O2 plasma etching is used to remove AZ4620 photoresist, oxygen volume flow rate 25 sccm, power 85 W, gas pressure 40 mTorr, etching time 10 minutes; after wet cleaning, it is dried.
[0041] Step 8: Metallization of the back side The same Ti / Cu / Ni / Au structure as the front side is used to ensure a symmetrical heat dissipation path.
[0042] The above description is merely an embodiment of this utility model and does not limit the patent scope of this utility model. Any equivalent structural or procedural transformations made based on the content of this utility model specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this utility model.
Claims
1. A micro-integrated high-precision laser packaging substrate, comprising an aluminum nitride ceramic substrate (1), characterized in that: A platinum metal thin film layer (2) is provided on the upper side of the aluminum nitride ceramic substrate (1), an aluminum oxide deposition layer (3) is provided on the upper side of the aluminum nitride ceramic substrate (1) and the platinum metal thin film layer (2), and a heat sink metal film layer (4) is provided on the upper side of the aluminum oxide deposition layer (3).
2. The micro-integrated high-precision laser packaging substrate according to claim 1, characterized in that: A metal layer (5) is provided on the lower side of the aluminum nitride ceramic substrate (1).
3. The micro-integrated high-precision laser packaging substrate according to claim 2, characterized in that: The structural metals of the metal layer (5) and the heat sink metal film layer (4) are Ti / Cu / Ni / Au.
4. The micro-integrated high-precision laser packaging substrate according to claim 1, characterized in that: The thickness of the platinum metal thin film layer (2) is ≤200 nm.