A cleaning method and cleaning equipment for a porous ceramic platform used in a silicon wafer thinning process

Abstract

This invention discloses a cleaning method and equipment for a porous ceramic platform, belonging to the field of semiconductor manufacturing technology. The porous ceramic platform is used to adsorb and fix silicon wafers during silicon wafer thinning processes, and its interior is equipped with air blowing, water spraying, and vacuuming channels. The cleaning method of this invention includes: a rough cleaning step, in which the air blowing and water spraying functions inside the platform are simultaneously turned on, and a coarse brush is used to brush for 10-30 seconds at a compression of 1-3 mm; a fine cleaning step, in which the air blowing function is turned off, but the water spraying function is kept on, and a fine brush is used to brush for 10-30 seconds at a compression of 1-3 mm; a rinsing step, in which an external spray is used to rinse for 5-15 seconds; and a rapid loading step, in which the silicon wafer is placed on the platform within 5 seconds after cleaning. This invention, through a combined internal and external cleaning method, effectively removes blockages within the micropores of the porous ceramic platform, avoids damage to the platform surface, and significantly improves the yield of silicon wafer thinning.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and more specifically to a cleaning method and equipment for a porous ceramic platform used in silicon wafer thinning processes. Background Technology

[0002] In semiconductor manufacturing, silicon wafer thinning is a critical step before chip packaging. During the thinning process, the silicon wafer is fixed to the surface of a Chuck Table (porous ceramic platform) using vacuum adsorption. The Chuck Table is typically made of porous ceramic material and has internal channels for air blowing, water spraying, and vacuuming. During vacuuming, the silicon wafer is firmly adsorbed onto the platform surface.

[0003] To ensure the uniformity and stability of adsorption, the Chuck Table needs to be cleaned regularly to remove contaminants such as residual silicon powder and polishing fluid particles from the surface and pores. Currently, the industry commonly uses brushes or oilstones for mechanical cleaning of the Chuck Table. However, existing cleaning processes have the following drawbacks: First, the cleaning effect is not thorough; brushes and oilstones can only remove surface dust and are ineffective against particles deep within the micron-sized pores. Second, long-term mechanical friction can damage the microstructure of the porous ceramic surface, leading to a decrease in the flatness of the platform surface. Third, when adsorbing silicon wafers for thinning, a damaged or contaminated platform can cause uneven stress on the back of the silicon wafer, directly resulting in pitted defects, which seriously affects product yield and production costs.

[0004] Therefore, developing a novel cleaning process that can deeply clean porous ceramic platforms while avoiding physical damage is of great practical significance. Summary of the Invention

[0005] The purpose of this invention is to provide a cleaning method and equipment for porous ceramic platforms, so as to solve the technical problems of poor cleaning effect, large damage to the platform, and pitting defects in silicon wafers in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a cleaning method for a porous ceramic platform, wherein the porous ceramic platform has an air blowing channel, a water spraying channel, and a vacuuming channel inside, and includes the following steps:

[0008] Step 1: Coarse Washing: Simultaneously activate the air blowing and water spraying functions inside the porous ceramic platform. Use a coarse brush to scrub the platform surface for 10-30 seconds, controlling the downward pressure of the brush to achieve a bristle compression of 1-3 mm. In this step, the internal air blowing and water spraying are activated simultaneously, creating a gas-liquid mixing "bubbling effect" on the platform surface. Gas is ejected from the micropores, "pushing" particles deep within the pores to the surface, rendering them free. The mechanical scraping action of the coarse brush then peels these free particles off the platform surface. Controlling the bristle compression to 1-3 mm ensures effective scraping force while avoiding excessive pressure that could damage the platform.

[0009] Step Two, Fine Cleaning: Turn off the air blowing function, keep the water spray function on, and use a fine-bristled brush to scrub the platform surface for 10-30 seconds. During brushing, control the downward pressure of the fine-bristled brush to compress the bristles by 1-3 mm. In this step, after turning off the air blowing function, only a liquid film formed by the water flow exists on the platform surface, providing a stable lubrication environment for the fine-bristled brush. The fine-bristled brush is made of soft material and mainly relies on its adsorption properties to remove submicron-sized particles, restoring the microscopic cleanliness of the platform surface.

[0010] Step 3: Rinsing: Rinse the platform surface for 5-15 seconds using an external spray system. This step thoroughly washes away contaminants that were brushed off in the first two steps but are still suspended on the platform surface, preventing secondary deposition.

[0011] Step 4, Rapid Loading: After cleaning, place the silicon wafer onto the porous ceramic platform within 5 seconds. Activate the negative pressure adsorption device before, simultaneously with, or after placing the wafer. Check the vacuum level after the wafer is in place. This step limits the waiting time window between cleaning and the start of the process, preventing the platform from being exposed to clean air for extended periods and adsorbing micro-dust, or from uneven moisture evaporation causing localized abnormal adsorption forces. This ensures that each silicon wafer begins the process when the platform is in optimal condition.

[0012] Preferably, in step one, the pressure of the internal air blowing is controlled at 0.10-0.25 MPa, the pressure of the internal water spray is controlled at 0.05-0.15 MPa, and the flow rate is controlled at 0.5-1.5 L / min. This pressure range is slightly higher than the bubble point pressure of porous ceramics, which can form a stable bubble flow without causing the ceramic structure to crack due to excessive pressure.

[0013] Preferably, in step two, the flow rate of the internal water spray is controlled at 0.8-2.0 L / min. This flow rate is slightly higher than that in the coarse washing stage to ensure the formation of a stable water film and avoid dry friction during fine brushing.

[0014] Preferably, in step three, the pressure of the external spray is controlled at 0.3-0.6 MPa, and the flow rate is controlled at 3-8 L / min. This pressure is sufficient to form a high-speed jet to impact and remove particles without damaging the platform.

[0015] Preferably, in step four, after the silicon wafer is placed, the vacuum level of the monitoring platform is checked to ensure it reaches -70kPa to -90kPa within 1 second. If it fails to do so, an alarm is triggered. This step verifies whether the pores of the platform are unobstructed after cleaning, ensuring that the adsorption function is normal.

[0016] The present invention also provides a cleaning apparatus for implementing the above-described cleaning method, comprising:

[0017] A porous ceramic platform is used to support silicon wafers to be processed; the porous ceramic platform is equipped with an air blowing channel, a water spraying channel and a vacuum pumping channel.

[0018] A rotary spindle is used to support and drive the porous ceramic platform to rotate.

[0019] The rough washing device and the fine washing device are used to perform the rough washing step and the fine washing step, respectively;

[0020] The Z-axis pressure control mechanism, connected to the coarse washing device and the fine washing device, is used to precisely control the amount of compression of the bristles on the platform surface.

[0021] An internal air / water control system is connected to the air blowing channel and water spraying channel of the porous ceramic platform to control the opening / closing of air blowing and water spraying, as well as the pressure and flow rate.

[0022] An external spray unit, located above or to the side of the porous ceramic platform, is used to perform the rinsing step;

[0023] A robotic transfer unit is used to transfer silicon wafers to a porous ceramic platform after cleaning.

[0024] The controller is electrically connected to the rotary spindle, the Z-axis pressure control mechanism, the internal air / water control system, the negative pressure drive device for vacuuming, the external spray unit, and the robotic arm conveying unit, and is used to control each component to execute the cleaning program according to the set timing and parameters.

[0025] Preferably, the Z-axis pressure control mechanism includes a servo motor and a pressure sensor, and achieves precise adjustment of the bristle compression through closed-loop feedback control to ensure constant brushing pressure under different platform warping conditions.

[0026] Preferably, the internal air / water control system includes a mass flow meter or a proportional valve for precisely controlling the flow rate of air blowing and water spraying.

[0027] Preferably, the controller includes a timer for starting a 5-second countdown at the end of the cleaning process and triggering the robotic arm transfer unit to perform the chip picking and loading operations.

[0028] Preferably, the coarse brush is made of nylon, and the fine brush is made of PVA sponge.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. Significantly improved cleaning effect: By combining internal bubbling with external brushing, it not only cleans the surface of the platform, but also effectively removes blockages deep in the micropores of porous ceramics, restoring the platform's breathability and adsorption uniformity.

[0031] 2. Avoid physical damage to the platform: By precisely controlling the bristle compression (1-3mm) and using segmented brushing (coarse brush + fine brush), the damage to the porous ceramic microstructure caused by traditional hard brushing is avoided, thus extending the service life of the platform.

[0032] 3. Eliminate silicon wafer pit defects: By quickly loading and locking the platform into its optimal state window within 5 seconds, secondary contamination is prevented, eliminating silicon wafer pit defects caused by platform issues at the source.

[0033] 4. High process stability: By digitizing and standardizing key parameters, the cleaning effect is highly repeatable, meeting the stringent requirements of semiconductor manufacturing for process capability index. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the overall structure of the cleaning equipment of the present invention.

[0036] Figure 2 This is a process flow diagram of the cleaning method of the present invention.

[0037] Figure 3 This is a timing control logic diagram of the controller of the present invention.

[0038] In the diagram: 1. Rotary spindle; 2. Coarse brush; 3. Fine brush; 4. Z-axis pressure control mechanism; 5. Chuck Table; 6. Internal air / water control system; 7. External spray unit; 8. Robotic arm conveying unit; 9. Controller; 10. Silicon wafer. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0040] like Figure 1 As shown, a cleaning apparatus for implementing the above-described cleaning method includes:

[0041] A porous ceramic platform (Chuck Table 5) is used to support the silicon wafer 10 to be processed. The porous ceramic platform 5 has an internal air blowing channel, a water spraying channel, and a vacuum pumping channel. In specific implementations, all three channels can be connected to the cavity below the porous ceramic platform 5 as needed. When the air blowing and water spraying devices are activated, the vacuum pumping channel is closed (the vacuum pumping channel valve can be closed or the vacuum pumping equipment can be stopped simultaneously; preferably, only the valve is closed for rapid response). Alternatively, multiple independent cavities or pipelines can be used to correspond to different through-holes on the porous ceramic platform 5, so as to make the water pressure and air pressure (including positive and negative pressure) of the through-holes in each area as consistent as possible. Multiple control valves and pressure regulating valves can be used to further precisely control the pressure and time.

[0042] A rotating spindle 1 is used to support and drive the porous ceramic platform 5 to rotate. In specific implementations, the rotating spindle 1 includes a motor, a gearbox, and an output spindle. The output spindle is connected to the porous ceramic platform 5 and its internal air / water control system located below it to drive the porous ceramic platform 5 to rotate. The internal air / water control system can be located in the cavity below the porous ceramic platform 5, or it can be connected to the cavity below the porous ceramic platform 5 through a rotating coupling device to provide gas and liquid passages. An annular sealing cavity is provided between the rotating coupling device and the cavity below the porous ceramic platform 5. The annular sealing cavity and the cavity below the porous ceramic platform 5 are connected through uniformly arranged through holes. The rotating coupling device and the outer shell of the cavity below the porous ceramic platform 5 are sealed by one or more layers of sealing rings and sealing grooves to allow for mutual rotation. The outer shell of the cavity below the porous ceramic platform 5 is rotatably fitted in the rotating coupling device, realizing both rotation and the flow of liquids and gases. Alternatively, the following scheme can be adopted: the internal air / water circuit control system is located in the frame below the porous ceramic platform 5. A through hole is provided at the center of the rotating spindle, and a cylinder with a through hole is inserted through the through hole. A sealed bearing is provided between the cylinder and the spindle. The lower end of the cylinder is fixed to the frame, and the lower end of its through hole is connected to the air blowing channel, water spraying channel, and vacuum pumping channel through a valve body. Its upper end is connected to the outer shell of the cavity below the porous ceramic platform 5 through a sealed bearing. Additional sealing grooves and sealing rings can be added to allow for both mutual selection and sealing. The upper end of the cylindrical through hole is connected to the cavity below the porous ceramic platform 5. Other coupling schemes can also be used.

[0043] The coarse washing device and the fine washing device are used to perform the coarse washing and fine washing steps, respectively. Each device is equipped with a coarse brush 2 and a fine brush 3 at its working end. They also include independent drive motors and reduction gears. The coarse washing device and the fine washing device can be installed at both ends of a rotating beam. This beam is connected to a Z-axis pressure control mechanism 4, which is connected to a motor and can rotate to switch the coarse washing device and the fine washing device to or from the working position. Simultaneously, the beam is also connected to the Z-axis pressure control mechanism 4 via a lifting device (such as a cylinder, hydraulic cylinder, or electric lead screw), allowing it to be vertically raised and lowered. Alternatively, the beam and the Z-axis pressure control mechanism 4 can be fixedly connected to the frame via a lifting device and lifting guide rails or columns for overall raising and lowering. To ensure control accuracy, independent lifting devices can be installed between the coarse washing device and the fine washing device and the beam. These devices can use servo motors and ball screws to precisely control the descent height, thereby precisely controlling the downward pressure of the fine brush and the coarse brush.

[0044] An internal air / water control system is connected to the air blowing channel and water spraying channel of the porous ceramic platform to control the opening / closing of air blowing and water spraying, as well as the pressure and flow rate.

[0045] The external spray unit 7 is located above or to the side of the porous ceramic platform and is used to perform the rinsing step. In the figure, it is located below the crossbeam. Alternatively, a separate mounting bracket can be installed on the frame. Its nozzles can be configured to adjust the height, direction, and angle as needed. This adjustment structure can be achieved using existing technology and will not be described in detail here.

[0046] The robotic arm transfer unit 8 is used to transfer silicon wafers to the porous ceramic platform after cleaning. It can employ a multi-axis robotic arm with a suction cup at the working end, using negative pressure adsorption to transfer the silicon wafers 10. A loading and unloading device can be installed next to the frame. This device includes a hopper 11 for loading silicon wafers 10, and an internal lifting mechanism for raising and lowering the tray carrying the silicon wafers. This ensures that the top silicon wafer is always flush with or just above the upper edge of the hopper 11, facilitating rapid adsorption and release by the robotic arm. This lifting mechanism can be implemented using a servo motor and ball screw, or other mechanisms.

[0047] The controller 9 is electrically connected to the rotary spindle, the Z-axis pressure control mechanism, the internal air / water control system, the negative pressure drive device for vacuuming, the external spray unit, and the robotic arm conveying unit. It is used to control each component to execute the cleaning program according to the set timing and parameters.

[0048] Preferably, the Z-axis pressure control mechanism includes a servo motor and a pressure sensor, and achieves precise adjustment of the bristle compression through closed-loop feedback control to ensure constant brushing pressure under different platform warping conditions.

[0049] Preferably, the internal air / water control system includes a mass flow meter or a proportional valve for precisely controlling the flow rate of air blowing and water spraying.

[0050] Preferably, the controller includes a timer for starting a 5-second countdown at the end of the cleaning process and triggering the robotic arm transfer unit to perform the chip picking and loading operations.

[0051] Preferably, the coarse brush is made of nylon, and the fine brush is made of PVA sponge.

[0052] This invention provides a cleaning method for a porous ceramic platform, wherein the porous ceramic platform has an air blowing channel, a water spraying channel, and a vacuuming channel inside, and includes the following steps:

[0053] Step 1: Coarse Washing: Simultaneously activate the air blowing and water spraying functions inside the porous ceramic platform. Use a coarse brush to scrub the platform surface for 10-30 seconds, controlling the downward pressure of the brush to achieve a bristle compression of 1-3 mm. In this step, the internal air blowing and water spraying are activated simultaneously, creating a gas-liquid mixing "bubbling effect" on the platform surface. Gas is ejected from the micropores, "pushing" particles deep within the pores to the surface, rendering them free. The mechanical scraping action of the coarse brush then peels these free particles off the platform surface. Controlling the bristle compression to 1-3 mm ensures effective scraping force while avoiding excessive pressure that could damage the platform.

[0054] Step Two, Fine Cleaning: Turn off the air blowing function, keep the water spray function on, and use a fine-bristled brush to scrub the platform surface for 10-30 seconds. During brushing, control the downward pressure of the fine-bristled brush to compress the bristles by 1-3 mm. In this step, after turning off the air blowing function, only a liquid film formed by the water flow exists on the platform surface, providing a stable lubrication environment for the fine-bristled brush. The fine-bristled brush is made of soft material and mainly relies on its adsorption properties to remove submicron-sized particles, restoring the microscopic cleanliness of the platform surface.

[0055] Step 3: Rinsing: Rinse the platform surface for 5-15 seconds using an external spray system. This step thoroughly washes away contaminants that were brushed off in the first two steps but are still suspended on the platform surface, preventing secondary deposition.

[0056] Step 4, Rapid Loading: After cleaning, place the silicon wafer onto the porous ceramic platform within 5 seconds. Activate the negative pressure adsorption device before, simultaneously with, or after placing the wafer. Check the vacuum level after the wafer is in place. This step limits the waiting time window between cleaning and the start of the process, preventing the platform from being exposed to clean air for extended periods and adsorbing micro-dust, or from uneven moisture evaporation causing localized abnormal adsorption forces. This ensures that each silicon wafer begins the process when the platform is in optimal condition.

[0057] Preferably, in step one, the pressure of the internal air blowing is controlled at 0.10-0.25 MPa, the pressure of the internal water spray is controlled at 0.05-0.15 MPa, and the flow rate is controlled at 0.5-1.5 L / min. This pressure range is slightly higher than the bubble point pressure of porous ceramics, which can form a stable bubble flow without causing the ceramic structure to crack due to excessive pressure.

[0058] Preferably, in step two, the flow rate of the internal water spray is controlled at 0.8-2.0 L / min. This flow rate is slightly higher than that in the coarse washing stage to ensure the formation of a stable water film and avoid dry friction during fine brushing.

[0059] Preferably, in step three, the pressure of the external spray is controlled at 0.3-0.6 MPa, and the flow rate is controlled at 3-8 L / min. This pressure is sufficient to form a high-speed jet to impact and remove particles without damaging the platform.

[0060] Preferably, in step four, after the silicon wafer is placed, the vacuum level of the monitoring platform is checked to ensure it reaches -70kPa to -90kPa within 1 second. If it fails to do so, an alarm is triggered. This step verifies whether the pores of the platform are unobstructed after cleaning, ensuring that the adsorption function is normal.

[0061] Compared with the prior art, the present invention has the following beneficial effects:

[0062] 1. Significantly improved cleaning effect: By combining internal bubbling with external brushing, it not only cleans the surface of the platform, but also effectively removes blockages deep in the micropores of porous ceramics, restoring the platform's breathability and adsorption uniformity.

[0063] 2. Avoid physical damage to the platform: By precisely controlling the bristle compression (1-3mm) and using segmented brushing (coarse brush + fine brush), the damage to the porous ceramic microstructure caused by traditional hard brushing is avoided, thus extending the service life of the platform.

[0064] 3. Eliminate silicon wafer pit defects: By quickly loading and locking the platform into its optimal state window within 5 seconds, secondary contamination is prevented, eliminating silicon wafer pit defects caused by platform issues at the source.

[0065] 4. High process stability: By digitizing and standardizing key parameters, the cleaning effect is highly repeatable, meeting the stringent requirements of semiconductor manufacturing for process capability index.

[0066] The cleaning method of the present invention is applicable to porous ceramic tables of different specifications in semiconductor silicon wafer thinning processes. The following specific embodiments are given for two mainstream porous ceramic tables used in semiconductor silicon wafer processing: 300mm and 200mm specifications. Comparative ratios are set to verify the effect. At the same time, durability tests and process reproducibility tests after cleaning are added to fully illustrate the implementation effect and technical advantages of the present invention.

[0067] Example 1 is applicable to cleaning porous ceramic platforms for 300mm silicon wafers.

[0068] The porous ceramic platform in this embodiment is a Chuck Table adapted to 300mm silicon wafers. The ceramic micropore diameter is 8-12μm, the overall flatness of the platform is ≤3μm, and it integrates independent air blowing channels, water spraying channels and vacuum channels. Each channel is equipped with an independent on / off control valve, which seamlessly connects with the internal air / water control system of the cleaning equipment.

[0069] The cleaning equipment uses the special cleaning device described in this invention. The coarse brush is made of nylon with a bristle diameter of 0.2 mm and a bristle length of 20 mm. The fine brush is made of PVA sponge with a porosity of 80% and a Shore hardness of 25 HA. The servo motor of the Z-axis pressure control mechanism has an accuracy of 0.01 mm, and the pressure sensor has a range of 0-50 N. The internal air / water control system is equipped with a mass flow meter (accuracy ±0.5%) and a proportional valve (adjustment accuracy ±0.01 MPa). The external spray unit uses fan-shaped nozzles with a nozzle coverage angle of 120°, which can achieve thorough cleaning of the platform surface.

[0070] The cleaning procedure should be executed precisely according to the following steps:

[0071] Rough cleaning step: The controller issues a command to drive the rotating spindle to rotate the porous ceramic platform at a constant speed of 200 RPM; at the same time, the internal air / water control system is activated, opening the air blowing channel and water spray channel, setting the internal air blowing pressure to 0.15 MPa, the internal water spray pressure to 0.1 MPa, and the flow rate to 1.0 L / min. The gas and liquid mix in the micropores inside the platform to form a stable bubbling effect, pushing the silicon powder and polishing liquid particles deep in the micropores to the surface of the platform; then the Z-axis pressure control mechanism drives the coarse brush to move downward, precisely controlling the bristle compression to 2.0 mm (corresponding to a downward pressure of 15 N). The coarse brush performs a circumferential brushing motion with a radius of 120-150 mm around the center of the platform, continuously brushing for 20 seconds, and removing free particles from the surface through mechanical scraping.

[0072] Fine cleaning steps: The controller closes the internal air blowing channel while keeping the internal water spray channel open, adjusting the water spray flow rate to 1.5L / min to form a uniform water film on the platform surface, avoiding dry friction damage to the platform; at the same time, the main spindle rotates to increase the platform rotation speed to 400RPM, the Z-axis pressure control mechanism raises the coarse brush, drives the fine brush to move downward, controls the bristle compression to 1.5mm (corresponding to a downward pressure of 8N), and the fine brush performs a reciprocating circular brushing motion along the entire radius of the platform for 15 seconds, using the adsorption properties of the PVA sponge to remove submicron (0.1-0.3μm) micro particles, restoring the microscopic cleanliness of the platform surface.

[0073] Rinsing steps: The Z-axis pressure control mechanism raises the fine brush, the controller starts the external spray unit, sets the spray pressure to 0.4MPa and the flow rate to 5L / min, and the fan-shaped nozzles rinse the rotating platform from 150mm above the platform without dead angles. At the same time, the platform rotation speed is increased to 500RPM, and centrifugal force is used to completely wash away the contaminants suspended on the platform surface after brushing. After rinsing for 10 seconds, the external spray unit is turned off, and the rotating spindle continues to rotate at 500RPM for 3 seconds to remove residual water stains on the platform surface using centrifugal force.

[0074] Rapid loading procedure: After rinsing, the controller immediately starts a 5-second countdown timer and simultaneously sends a wafer loading command to the robotic arm transfer unit; the robotic arm picks up a 300mm silicon wafer from the clean silicon wafer stage and precisely places the wafer in the center of the porous ceramic platform within 3 seconds; the controller then activates the platform vacuum channel, and the vacuum detection module monitors the platform vacuum level in real time. If the vacuum level reaches **-85kPa** within 0.8 seconds, meeting the process requirements, the silicon wafer thinning process begins; if the vacuum level does not reach the -70kPa to -90kPa range within 1 second, the equipment immediately issues an audible and visual alarm, pauses the process, and prompts the operator to re-inspect the platform.

[0075] Example 2: Cleaning of porous ceramic platforms suitable for 200mm silicon wafers

[0076] The porous ceramic platform in this embodiment is a Chuck Table adapted to a 200mm silicon wafer. The ceramic micropore diameter is 6-10μm, the overall flatness of the platform is ≤2μm, and the internal channel structure is the same as in Example 1. The brush specifications of the cleaning equipment are adapted and adjusted: the coarse brush is made of nylon with a bristle diameter of 0.18mm and a bristle length of 18mm; the fine brush is made of PVA sponge with a porosity of 80% and a Shore hardness of 25HA; the remaining equipment parameters are the same as in Example 1.

[0077] The cleaning procedure is performed as follows:

[0078] Preliminary cleaning steps: Set the platform rotation speed to 180 RPM, and simultaneously turn on the internal air blowing (pressure 0.12 MPa) and internal water spray (pressure 0.08 MPa, flow rate 0.8 L / min); control the compression of the coarse brush to 1.5 mm (downward pressure 12 N), and perform a circular brushing motion with a radius of 80-100 mm for 15 seconds.

[0079] Fine cleaning steps: Turn off the internal air blowing, adjust the internal water spray flow rate to 1.0L / min, and increase the platform rotation speed to 350RPM; control the fine brush compression to 1.0mm (downward pressure 6N), and perform full-radius reciprocating circumferential brushing for 10 seconds.

[0080] Rinsing steps: The external spray unit is set to a pressure of 0.35MPa and a flow rate of 4L / min. The platform rotation speed is increased to 450RPM. Rinse for 8 seconds without dead angles, followed by centrifugal drying for 2 seconds.

[0081] Rapid loading process: After cleaning, the controller starts a 5-second countdown. The robotic arm completes the loading of the 200mm silicon wafer within 2.5 seconds. The vacuum detection module detects a vacuum level of -82kPa within 0.6 seconds, which meets the process requirements, and the thinning process is initiated.

[0082] Comparative Example 1: Traditional hard-bristle brush cleaning process (compatible with 300mm platform)

[0083] Using industry-standard cleaning methods, a hard nylon brush (0.3mm bristle diameter, Shore hardness 60HA) was used to scrub the 300mm porous ceramic platform. During scrubbing, the platform's internal air blowing and water spraying functions were not activated; the scrubbing relied solely on mechanical scraping with the brush. The scrubbing pressure was 30N, and the scrubbing lasted for 30 seconds. After scrubbing, the rotating spindle was turned off, and the platform was allowed to air dry naturally in the cleanroom for 2 minutes. Then, the silicon wafers were manually placed on the platform, and vacuum adsorption was initiated. There was no real-time vacuum monitoring or alarm function.

[0084] Comparative Example 2: Single brush + external water rinsing cleaning process (suitable for 300mm platform)

[0085] Using the same nylon coarse brush as in Example 1, the internal air blowing and water spraying of the platform were turned off during brushing, and only the external low-pressure water was turned on (pressure 0.1MPa, flow rate 2L / min). The brush compression was 3mm, and the brushing lasted for 30 seconds. After the water was rinsed, the silicon wafer was allowed to air dry for 1 minute before loading. Vacuum degree monitoring was only performed after adsorption was completed, and there was no 1-second time limit requirement.

[0086] Effect testing and verification

[0087] To fully verify the technical effectiveness of the cleaning method of the present invention, surface particle size and adsorption uniformity were tested on the cleaning platforms of Examples 1, 2, 1, and 2, respectively, and the silicon wafer pit defect rate was statistically analyzed after the silicon wafer thinning process. At the same time, the cleaning platform of Example 1 was subjected to durability testing (platform performance was tested after 1000 consecutive cleaning cycles) and process reproducibility testing (50 consecutive cleaning cycles with the same parameters, and the fluctuation range of various indicators was tested). All tests were completed in a Class 100 cleanroom, and the testing equipment was a semiconductor-specific laser particle counter, a vacuum distribution tester, and a silicon wafer surface defect detector.

[0088] Test 1: Basic performance tests (surface particle size, uniformity of adsorption force, and rate of pitting defects)

[0089]

[0090] Test 2 Durability Test (Example 1: Platform after 1000 consecutive cleaning cycles)

[0091]

[0092] Test 3: Process reproducibility test (Example 1: 50 consecutive cleaning cycles with the same parameters)

[0093]

[0094] Test Result Analysis

[0095] Basic performance: Compared with comparative examples 1 and 2, the cleaning methods of Examples 1 and 2 reduced the particle size of the platform surface by more than 70%, improved the uniformity of adsorption force by more than 50%, and reduced the defect rate of silicon wafer pits to below 0.15%. The core reason is that the combination of internal bubbling and external segmented brushing achieves deep cleaning of contaminants deep in the micropores. At the same time, precise pressure control and soft fine brush effectively avoid damage to the platform surface, and 5-second rapid loading eliminates secondary pollution and adsorption abnormalities caused by uneven moisture evaporation.

[0096] Durability: After 1000 consecutive cleaning cycles, the performance of the platform in Example 1 showed only a slight decline, and the surface flatness of the platform did not change significantly. This indicates that the cleaning method of the present invention causes minimal physical damage to the porous ceramic platform and significantly extends the service life of the platform. Compared with the traditional process (the platform performance generally declines significantly after 300 consecutive cleaning cycles), the service life is increased by more than 2 times.

[0097] Reproducibility: After 50 consecutive cleaning cycles with the same parameters, the fluctuation range of each detection index was within 10%, indicating that the present invention significantly improves the process stability and repeatability after digitizing and standardizing the key cleaning parameters, thus meeting the stringent requirements of semiconductor manufacturing for process capability index.

[0098] All of the above-mentioned optional technical solutions can be combined in any way to form optional embodiments of the present invention, and will not be described in detail here.

[0099] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A cleaning method for a porous ceramic platform, wherein the porous ceramic platform is internally provided with an air blowing channel, a water spraying channel, and a vacuum pumping channel, characterized in that, Includes the following steps: Step 1: Rough cleaning: Simultaneously turn on the air blowing and water spraying functions inside the porous ceramic platform, and use a coarse brush to clean the platform surface for 10~30 seconds. When brushing, control the downward pressure of the coarse brush to compress the bristles by 1~3mm. Step 2, Fine cleaning: Turn off the air blowing function, keep the water spraying function on, and use a fine brush to scrub the platform surface for 10~30 seconds. When scrubbing, control the downward pressure of the fine brush so that the bristles are compressed by 1~3mm. Step 3, Rinsing: Rinse the platform surface with an external spray device for 5-15 seconds; Step 4, Rapid Loading Step: After cleaning, place the silicon wafer on the porous ceramic platform within 5 seconds. Turn on the negative pressure adsorption device before, simultaneously with, or after placing the silicon wafer in place. Check the vacuum level after the silicon wafer is in place.

2. The cleaning method according to claim 1, characterized in that, In step one, the internal air pressure is controlled at 0.10-0.25 MPa, the internal water pressure is controlled at 0.05-0.15 MPa, and the flow rate is controlled at 0.5-1.5 L / min.

3. The cleaning method according to claim 1, characterized in that, In step two, the flow rate of the internal water spray is controlled at 0.8-2.0 L / min.

4. The cleaning method according to claim 1, characterized in that, In step three, the pressure of the external spray is controlled at 0.3-0.6 MPa, and the flow rate is controlled at 3-8 L / min.

5. The cleaning method according to claim 1, characterized in that, In step four, after the silicon wafer is placed, the monitoring platform is checked to see if the vacuum level reaches -70kPa to -90kPa within 1 second. If it does not reach this level, an alarm is triggered.

6. A cleaning apparatus for implementing the cleaning method according to any one of claims 1-5, characterized in that, include: Porous ceramic platforms are used to support silicon wafers that need to be processed; The porous ceramic platform is equipped with an air blowing channel, a water spraying channel, and a vacuum pumping channel. A rotary spindle is used to support and drive the porous ceramic platform to rotate. The rough washing device and the fine washing device are used to perform the rough washing step and the fine washing step, respectively; The Z-axis pressure control mechanism, connected to the coarse washing device and the fine washing device, is used to precisely control the amount of compression of the bristles on the platform surface. An internal air / water control system is connected to the air blowing channel and water spraying channel of the porous ceramic platform to control the opening / closing of air blowing and water spraying, as well as the pressure and flow rate. An external spray unit, located above or to the side of the porous ceramic platform, is used to perform the rinsing step; A robotic transfer unit is used to transfer silicon wafers to a porous ceramic platform after cleaning. The controller is electrically connected to the rotary spindle, the Z-axis pressure control mechanism, the internal air / water control system, the negative pressure drive device for vacuuming, the external spray unit, and the robotic arm conveying unit, and is used to control each component to execute the cleaning program according to the set timing and parameters.

7. The cleaning equipment according to claim 6, characterized in that, The Z-axis pressure control mechanism includes a servo motor and a pressure sensor, and achieves precise adjustment of the bristle compression amount through closed-loop feedback control.

8. The cleaning equipment according to claim 6, characterized in that, The internal air / water control system includes a mass flow meter or proportional valve for precisely controlling the flow rate of air blowing and water spraying.

9. The cleaning equipment according to claim 6, characterized in that, The controller includes a timer for starting a 5-second countdown at the end of the cleaning process and triggering the robotic arm transfer unit to perform the chip picking and loading operations.

10. The cleaning equipment according to claim 6, characterized in that, The coarse brush is made of nylon, and the fine brush is made of PVA sponge.

Images