Method for controlling liquid tension to improve wafer drying efficiency

Abstract

This invention relates to a method for controlling liquid tension to improve wafer drying efficiency. The method includes the following steps: (1) inserting a wafer cassette into a drying groove via a swing mechanism, loading wafer plates into the wafer cassette, and connecting the drying groove to a dome-shaped top cover to maintain tight contact and evacuating trace gases; (2) injecting room-temperature nitrogen through the dome-shaped top cover and injecting ultrapure water into the drying groove to wet the wafer surfaces; (3) injecting a mixture of isopropanol and heated nitrogen into the drying groove using a dedicated integrated module after the wafer surfaces have been wetted, and discharging the ultrapure water from the bottom of the drying groove at a controlled speed (S1); (4) operating the swing mechanism to swing the wafer plate in a planetary motion during the ultrapure water discharge process to rapidly release water molecules on the wafer plate; and (5) completing the process by repeating this process until the wafer is completely dried. In this invention, the planetary arc swing drying technique is used to rapidly remove residual moisture from the wafer surface, effectively controlling the liquid tension and achieving rapid wafer drying.

Description

[Technical Field]

[0001] The present invention relates to the semiconductor field, and more particularly to a method for controlling liquid tension during wafer drying to improve wafer drying efficiency. [Background technology]

[0002] Drying technology is essential in semiconductor wafer cleaning, and up to now, different wafer drying technologies exist for different wafer products. Wafer drying is the final operation in the wet cleaning process, and it is necessary to ensure the effective removal of residual moisture from the wafer surface and the control of surface cleanliness. Continuous optimization and efficiency improvement of drying methods are particularly emphasized in the development of wafer cleaning equipment and technology. There are many methods applied to the wafer drying process, and effective batch drying within a specified time will affect the effective operation of the entire batch and the entire work in the wafer cleaning process. Therefore, wafer drying methods with effective drying efficiency are currently a particularly important part of wafer wet cleaning technology.

[0003] In the prior art, utility model patent CN204257600U discloses a cleaning groove for cleaning semiconductor wafers. During the cleaning process, an external magnetic field is used to change the surface tension of the liquid, and a surface tensiometer is used to monitor the liquid surface tension in real time. The monitored information is fed back to a magnetizer to control the magnetic field strength and maintain the magnetic field strength at a predetermined value, thereby stabilizing the water surface tension at a required value and meeting the process needs of wafer manufacturing. According to this technology, a magnetizer is specially arranged in the cleaning groove to generate the magnetic field, which is complex to operate. To maintain the water surface tension stably, the magnetic field strength must be controlled in real time, which increases operational difficulties and further affects the efficiency of cleaning and drying. Therefore, a simpler and faster method is needed to control the liquid tension and improve wafer drying efficiency. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Chinese Utility Model Patent No. CN204257600U Summary of the Invention [Problem to be solved by the invention]

[0005] To address the above-mentioned problems in the prior art, the present invention proposes a method for controlling liquid tension to improve wafer drying efficiency during wafer drying. As proposed by the present invention, the method for controlling liquid tension to improve wafer drying efficiency during wafer drying effectively controls the liquid tension, and through comprehensive control, realizes rapid release of water molecules on the wafer, thereby achieving rapid drying of the wafer. [Means for solving the problem]

[0006] To achieve the above-mentioned invention objectives, the technical solutions provided by the present invention patent are as follows: A method for controlling liquid tension that can improve wafer drying efficiency, wherein during wafer drying, residual moisture on the wafer surface is removed using isopropanol in a gas phase substitution process with isopropanol and nitrogen using a planetary arc oscillation drying technique, the method comprising: a first step of loading a plurality of wafer plates into a wafer cassette, placing the wafer cassette on a swinging mechanism, inserting the swinging mechanism carrying the wafers into a drying groove body, connecting the upper cover dome of the drying equipment to the drying groove body, maintaining the tightness of the cabin after connection, and evacuating trace gases from the cabin; Drying groove body DIW At the same time, room temperature nitrogen was injected through the upper cover dome and into the dry groove body. DIW a second step of wetting the surface of the wafer plate so that the liquid level exceeds the top edge of the wafer, and continuously injecting room temperature nitrogen into the drying groove during the wetting period; DIW After the surface infiltration of the wafer plate is completed, the injection of room temperature nitrogen is stopped. A mixture of isopropanol and heated nitrogen is injected into the drying groove from the top dome using a dedicated integrated module. DIWS1, which discharges from the bottom to control the speed, and DIW As the liquid level continues to fall, DIW During the discharging process, the swing mechanism is operated to carry the wafer plates and form a planetary swing, so that each wafer plate generates an arc-shaped periodic small angle motion. During the swinging process of the wafer plates, DIW A tensile phenomenon occurs at the contact point between the liquid surface and the wafer surface, DIW The tension T1 of the liquid phase increases due to tension, and the DIW The surface tension T2 formed by the liquid phase becomes smaller due to tension, and the isopropanol liquid film becomes thinner due to being pulled by tension and shaking. DIW The water film is pulled and thinned, and the water molecules in the thinned water film move laterally faster, causing the water molecules on the wafer plate to quickly separate. This is the third step of controlling the liquid tension (S2). DIW and a fourth step of operating the rocking mechanism to continuously rock the wafer cassette until the liquid level is lower than the wafer cassette, thereby completing the first stage of drying, checking whether it is necessary to repeat cleaning and drying, and if necessary, repeating the second and third steps to perform the second and subsequent stages of drying until the drying of the wafer plate is completed.

[0007] In the third step, the wafer cassette is driven by the swinging mechanism to swing regularly within the drying groove, causing the wafer plates arranged in the wafer cassette to swing regularly and move back and forth symmetrically within the tilt angle around the center of the wafer plate as the axis.

[0008] In a further structural design, the swing mechanism includes a drive motor, a slide track, a slide block, a pivot track, and an L-shaped swing arm, the slide track and the pivot track are arranged in parallel, the slide track is located above the pivot track, and the slide block is attached to the slide track so as to slide. The drive motor drives the slide block to perform reciprocating motion on the slide track, thereby forming a linear robot. The L-shaped swing arm includes at least two parallel first and second arms, a slide groove formed on the upper part of the first arm along its length, a slide wheel attached to the slide block corresponding to the slide groove, and the slide wheel is attached in the slide groove. The lower end of the first arm is pivotally attached to a connection point on the pivot track, and a wafer cassette receiving area is provided at the lower end of the second arm.

[0009] In a further structural design, the linear robot moves back and forth and drives the L-shaped swing arm to rotate with a fixed axis, forming an arc swing mode with a fixed axis.

[0010] During the rocking process of the wafer in the third step, the water molecules flow downward on the tilted wafer plate due to the rocking, slowly lowering the liquid surface, and the mixture of isopropanol and hot nitrogen descends along with the liquid surface, the interface angle of the water molecules is increased by the rocking, and the planar included angle between the surface where the wafer is located and the liquid surface exceeds 90 degrees, making the water molecules easy to peel off from the wafer surface, and by moving back and forth, the peeling speed of the water molecules on the wafer surface is increased and the peeling effect is strengthened. During the rocking process of the wafer plate, the upper part of the wafer plate is a dry area, and its lower part is a wet area. Due to the Marangoni effect, a thick water film is formed in the dry area at the boundary between the liquid surface and the wafer, which is then mixed with the isopropanol gas phase. DIW The surface tension formed by the liquid phase is T2, and the tension of the DIW liquid phase is T1. When rocking, the isopropanol liquid film becomes thinner due to the tension and rocking, and the water molecules in the water film move sideways faster due to the tension, resulting in faster detachment of the water molecules.

[0011] In further structural design, the movement and positioning method of the swing mechanism is as follows: When the L-shaped swing arm is driven to move back and forth so as to rotate with its axis fixed, three positioning sensors are arranged to detect the corresponding swing positions when the linear robot moves back and forth in a reciprocating manner; The position of swinging to the front end is positioned as A0, the center rest normal position is positioned as A1, and the position of swinging to the rear end is positioned as A2; When the wafer oscillates, the corresponding phase performs an oscillating motion, corresponding to the center normal, the center rest normal position is positioned as A1, the corresponding relative phase included angle of the wafer oscillating is 0 degrees, the position of oscillating to the front end is positioned as A0, the corresponding relative phase included angle of the wafer oscillating is +θ degrees, and 2°<θ<15°; The position of the swing to the rear end is positioned as A2, and the corresponding relative phase angle of the wafer swing is -θ degrees, where 2°<θ<15°.

[0012] In a further structural design, in the third step, the mixture of isopropanol and heated nitrogen is produced from a dedicated integrated module, transferred to the top cover dome, and sprayed downward into the drying groove, where the isopropanol and water molecules evaporate as gas phase and move upward, and the water molecules in liquid phase move downward under tension control; DIW is injected or discharged from the bottom of the drying channel.

[0013] In further structural design, a dedicated integrated module structure is used for the isopropanol input line, the circulation DIW Input pipeline, circulation DIW Output pipe, heated nitrogen input pipe, mixing tank body and mixed gas and liquid coexistenceThe mixing tank body structure includes a housing and a mixing tank, the housing is a box-shaped structure having a tank body door plate, at least one mixing tank is provided in the housing, an isopropanol input end port is provided on the front side wall of the housing at a position close to the bottom, the isopropanol input end port is connected to the isopropanol input pipe line, and the circulating DIW Input pipeline and circulation DIW Each is connected to a corresponding output line. DIW Input terminal and D IW a heated nitrogen input port on the rear wall of the housing, the heated nitrogen input port being connected to the heated nitrogen input pipe; a mixed gas-liquid mixture output port on the rear wall of the housing, the mixed gas-liquid mixture output port being connected to the mixed gas-liquid mixture; coexistence connected to one end of the output pipe, coexistence The other end of the output pipe is connected to the top cover dome, thereby transporting a mixture of isopropanol and heated nitrogen into the drying groove. The mixing tank has a cylindrical outer shape, and the inside of the mixing tank has a three-layer structure including a vortex mixing channel, a buffer reflux channel, and a hot water bath area. The vortex mixing channel is an inverted cone-shaped cavity located in the center of the mixing tank. The mixing tank has a tank body inlet at the center of the bottom and a tank body outlet at the center of the top. The tank body inlet is connected to the isopropanol input port, thereby receiving isopropanol and inputting it into the vortex mixing channel. The upper position of the buffer reflux channel in the mixing tank is connected to the heated nitrogen input port, thereby receiving heated nitrogen. The hot water bath area in the mixing tank is DIW Input terminal and DIW By connecting to the output end port, circulation DIW The outlet of the tank body is connected to the output end port of the mixed gas-liquid mixture.

[0014] The liquid tension control method of the present invention, which can improve wafer drying efficiency, further relates to a safe control method for supplying a mixture of isopropanol and hot nitrogen, which includes the steps of determining a demand target for controlling the nitrogen mixed gas / isopropanol mixture → checking and controlling the isopropanol supply status → checking exhaust control → checking cleanliness detection control → performing mixing confirmation control → performing output confirmation corresponding to the drying operation → performing drying output.

[0015] In the liquid tension control method of the present invention, which can improve wafer drying efficiency, when the liquid level rises and falls during the arc-shaped oscillation process to perform the drying operation, the temperature of the isopropanol liquid is controlled; if it is room temperature, it is controlled to 25 degrees and set to isopropanol room temperature control, and if it is high, it is controlled to 60 degrees (controlled to approach the critical state).The temperature of the nitrogen gas is controlled to 30 degrees and set to nitrogen room temperature control if it is room temperature, and if it is high, it is controlled to 120 degrees, and stable control is achieved by heating at high temperatures. [Effects of the Invention]

[0016] Based on the above technical solution, the ship pressure pipeline drug filling system of the present invention can achieve the following technical effects through practical application: 1. The liquid tension control method according to the present invention, which can improve wafer drying efficiency, involves two synchronized operations. This allows for the control of liquid tension and effectively completes the drying process of the wafer plate. First, a dedicated integrated module is used to input isopropanol and heated nitrogen, thereby improving the temperature and purity of the isopropanol. The low liquid tension of high-purity isopropanol accelerates the desorption of moisture from the wafer plate. Second, a small-angle oscillation is created by the oscillation mechanism. DIW The angle between the liquid and the wafer plate is regularly changed to change the magnitude of the liquid tension at both ends of the interface, resulting in the deposition of the liquid on the wafer plate. DIW The thinning of the water film allows water molecules to quickly separate from the wafer surface, greatly improving drying efficiency. 2. In the liquid tension control method according to the present invention, which can improve wafer drying efficiency, a swinging mechanism When the wafer cassette is oscillated, the wafer plate is tilted and the water molecules flow downward. DIW The liquid level of the isopropanol and hot nitrogen mixture was slowly lowered. DIW The water molecules descend along with the liquid surface, and the interfacial angle of the water molecules is increased by the oscillation, so that the planar included angle between the surface on which the wafer plate is located and the liquid surface exceeds 90 degrees, the water film adhering to the wafer plate surface becomes thinner, and the water molecules in the water film are easily peeled off from the wafer plate surface. The reciprocating oscillation operation increases the peeling speed of the water molecules on the wafer surface, strengthening the peeling effect. 3. In the method for controlling liquid tension according to the present invention, the drying air flow path is improved and optimized. This increases the drying speed of the wafer products during the drying process, improving the drying efficiency. By modifying the paths of the isopropanol and hot nitrogen airflow, a combined effect is achieved, improving the drying efficiency and achieving the optimal drying efficiency ratio in the same time. 4. In the method for controlling liquid tension according to the present invention, a dedicated integrated module is designed. , isopropanol and heated nitrogen are provided, and a mixed liquid pressurization is established, which helps improve the diffusion and distribution ability of IPA / N2, strengthens the Marangoni drying ability, and enhances the distribution ability of the finely divided organic solvent, which removes water molecules through tension, on the wafer surface. Specifically, in the integrated module, the special temperature maintenance unit that controls heating and the heated nitrogen source unit, which are connected to the main mixing tank module, work together to improve the control efficiency of heated nitrogen, and achieve stable overall heating and auxiliary heating of nitrogen. [Brief explanation of the drawings]

[0017] [Figure 1] 3A to 3C are schematic diagrams illustrating a wafer drying process in the method for controlling liquid tension, which can improve wafer drying efficiency, according to the present invention. [Figure 2] 1 is a schematic diagram illustrating the layout of a wafer cassette in a drying device in accordance with a method for controlling liquid tension that can improve wafer drying efficiency according to the present invention; [Figure 3] 1 is a schematic diagram illustrating an initial state of a drying process in a liquid tension control method capable of improving wafer drying efficiency according to the present invention. [Figure 4] 1A and 1B are schematic diagrams illustrating intermediate states of the drying process in the liquid tension control method of the present invention, which can improve wafer drying efficiency. [Figure 5] 1 is a schematic diagram illustrating the final state of the drying process in the liquid tension control method of the present invention, which can improve wafer drying efficiency. FIG. [Figure 6] 1 is a schematic diagram illustrating an attachment state of a rocking device and a wafer cassette in a method for controlling liquid tension capable of improving wafer drying efficiency according to the present invention. FIG. [Figure 7] 1 is a structural schematic diagram of a rocking device in a liquid tension control method capable of improving wafer drying efficiency according to the present invention; [Figure 8] 10A and 10B are schematic diagrams illustrating the swinging state of a wafer cassette in the liquid tension control method capable of improving wafer drying efficiency of the present invention. [Figure 9] 3A to 3C are schematic diagrams illustrating different states of a wafer when a wafer cassette is rocking in the method for controlling liquid tension to improve wafer drying efficiency according to the present invention; [Figure 10] 1 is a schematic diagram of a connection portion between the liquid surface and the wafer when the wafer is oscillating and tilting in a method of controlling liquid tension capable of improving wafer drying efficiency according to the present invention; FIG. [Figure 11] 10 is a schematic diagram showing a change in liquid tension when the wafer is oscillating and tilting in the liquid tension control method capable of improving wafer drying efficiency of the present invention. FIG. [Figure 12] 1 is a schematic diagram illustrating the principle of how the water flow increases due to a change in liquid tension in a method of controlling liquid tension that can improve wafer drying efficiency according to the present invention. FIG. [Figure 13] 1 is a schematic diagram of the structure and pipe connection of a dedicated integrated module in the liquid tension control method of the present invention, which can improve wafer drying efficiency. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention will be described in detail below in combination with the drawings and specific embodiments to make its configuration and operation method more clearly understandable, but this does not limit the protection scope of the present invention.

[0019] This invention relates to the realization of drying technology that can be combined with batch-type wafer wet cleaning equipment, and focuses on the innovation of the process principles involved in drying wafers. The drying process of this invention is used in the gas phase replacement process of organic solvent isopropanol (IPA) with nitrogen (N2), which results in: The method for removing residual moisture from the wafer surface using IPA has been further optimized. This drying method corresponds to the traditional Marangoni wafer drying technology, and uses the two-phase movement of isopropanol solvent and water molecules to exert the effects of tensile diffusion and vertical lifting, and the difference in tension between water molecules and isopropanol molecules causes moisture to be removed from the wafer surface.

[0020] As shown in Figure 1, as an optimization of the Marangoni wafer drying technique, the method of the present invention aims to replace the liquid phase of ultrapure water with the vapor phase of the organic solvent isopropanol and heated nitrogen during wafer drying, and to remove residual moisture on the wafer surface with isopropanol (IPA) using a planetary arc oscillation drying technique. The method of the present invention is applied to wafer drying equipment and specifically includes the following steps: Step 1: Load multiple wafer plates into a wafer cassette, place the wafer cassette on the oscillating mechanism, insert the oscillating mechanism carrying the wafer cassette into the drying groove, and connect the top cover dome of the drying equipment to the drying groove to maintain the tightness of the cabin after connection and evacuate trace gases inside the cabin. In this step, the wafer plates are grouped together and placed in the wafer cassette, enabling simultaneous cleaning and drying of multiple wafer plates and improving efficiency. The wafer cassette is placed on a specialized oscillating mechanism, and part of the oscillating mechanism is inserted into the drying groove to create a micro-vacuum environment inside the drying groove, ensuring that the wafer plate cleaning and drying operations are carried out in a closed and safe environment. Step 2: Inject ultrapure water into the drying groove, then inject room temperature nitrogen through the top cover dome to wet the wafer surface until the level of the ultrapure water in the drying groove exceeds the top edge of the wafer. During the soaking period, continuously inject room temperature nitrogen into the drying groove. Injecting room temperature nitrogen in this step minimizes the oxygen content in the drying groove space, further reducing the impact of oxidation on the wafer surface. Third step: After the surface of the wafer plate is completely infiltrated with ultrapure water, the injection of room temperature nitrogen is stopped. S1, injecting a mixture of isopropanol and heated nitrogen into the drying trough from the top dome using a dedicated integrated module, and draining the ultrapure water in the drying trough from the bottom at a controlled rate; and As the ultrapure water level continues to drop, the rocking mechanism is operated to carry the wafer plate and form a planetary rocking motion during the ultrapure water discharge process, thereby generating periodic small-angle arc-shaped motions on each wafer plate. During the rocking process of the wafer plate, a tensile phenomenon occurs at the contact point between the ultrapure water level and the wafer plate surface, causing the tension T1 of the ultrapure water liquid phase to increase due to the tension, and the surface tension T2 formed by the isopropanol gas phase and the ultrapure water liquid phase to decrease due to the tension. The isopropanol liquid film becomes thinner due to the tension and rocking, and the ultrapure water film becomes thinner due to the tension. The water molecules in the thinner water film move laterally more quickly, causing the water molecules on the wafer plate to quickly separate. This controls the liquid tension S2.

[0021] The core of liquid tension control is this step, which separates the remaining water molecules in the ultrapure water from the wafer surface in two ways: 1) injecting a mixture of heated nitrogen and isopropanol (IPA) to maximally purify the isopropanol, thereby reducing the liquid tension at the interface between the isopropanol and ultrapure water, allowing the heated nitrogen to further evaporate the water molecules; 2) as the ultrapure water level descends, the oscillation mechanism drives the wafer plate to continuously oscillate periodically, thereby stretching and thinning the water film at the interface between the ultrapure water and the wafer plate; and under the action of liquid tension, the water molecules in the thinned water film on the wafer plate quickly converge on the ultrapure water surface along the wafer plate and quickly separate from the wafer plate surface, achieving comprehensive control of liquid tension and achieving the overall effect of accelerating the drying of the wafer plate.

[0022] Step 4: Operate the rocking mechanism to continuously rock the wafer cassette until the ultrapure water is discharged and the liquid level is lower than the wafer cassette, completing the first stage of drying. Check whether it is necessary to repeat the cleaning and drying process. If necessary, repeat steps 2 and 3 to perform the second and subsequent stages of drying until the wafer plate is completely dried.

[0023] In the method of controlling liquid tension to improve wafer drying efficiency according to the present invention, as shown in Figures 3, 4, and 5, a mixture of isopropanol and heated nitrogen (1) is injected into the drying channel at point A in Figure 2 during the drying process. The mixture of isopropanol and heated nitrogen (1) is sprayed downward, vaporizing isopropanol and water molecules (2) and moving upward. The tension control causes the liquid water molecules (3) to move downward. Liquid (4) is discharged from the bottom of the drying channel at point B in Figure 2, and the discharged liquid is primarily ultrapure water. As shown in Figure 2, during the liquid discharge process, the wafer cassette is driven by the swinging mechanism to swing regularly, causing the wafer plates arranged in the wafer cassette to swing regularly and reciprocate symmetrically within the tilt angle around the center of the wafer. For specific motion patterns, see Figures 7 and 8.

[0024] The mixture of isopropanol and heated nitrogen is produced in a dedicated integrated module, which produces a mixture of isopropanol and heated nitrogen and delivers it to the top cover dome, where it is sprayed downward into the drying groove. Within the drying groove, the isopropanol and water molecules evaporate as a gas and move upward. Under tension control, the liquid water molecules move downward. Liquid containing ultrapure water is injected or discharged from the bottom of the drying groove.

[0025] As shown in FIG. 13, the dedicated integrated module structure includes an isopropanol input pipe 16, a circulating ultrapure water input pipe, a circulating ultrapure water output pipe, a heated nitrogen input pipe 17, a mixing tank body 15, and a mixed gas / liquid coexistence The mixing tank body 15 has a structure including a housing and a mixing tank, the housing being a box-shaped structure with a tank body door plate, and at least one mixing tank provided within the housing. An isopropanol input port is provided on the front wall of the housing near the bottom, and the isopropanol input port is connected to the isopropanol input port 16. One side wall of the housing is provided with an ultrapure water input port and an ultrapure water output port, which are connected to the circulating ultrapure water input port and the circulating ultrapure water output port, respectively. A heated nitrogen input port is provided on the rear wall of the housing, and the heated nitrogen input port is connected to the heated nitrogen input port 17. The rear wall of the housing is further provided with a mixed gas-liquid mixture output port, which is connected to the mixed gas-liquid mixture output port. coexistence The mixed gas and liquid are connected to one end of the output pipe 18. coexistenceThe other end of the output pipe 18 is connected to the top cover dome 13, thereby transporting the mixture of isopropanol and heated nitrogen into the drying groove 12. A wafer cassette is placed on the rocking mechanism 14, and the wafer cassette is positioned within the drying groove 12. The mixing tank has a cylindrical exterior and a three-layer structure including a vortex mixing channel, a buffer reflux groove, and a hot water bath area. The vortex mixing channel is an inverted cone-shaped cavity located in the center of the mixing tank. The mixing tank has a tank body inlet at the center of the bottom and a tank body outlet at the center of the top. The tank body inlet is connected to the isopropanol input port to receive isopropanol and input it into the vortex mixing channel. The upper position of the buffer reflux groove in the mixing tank is connected to the heated nitrogen input port to receive heated nitrogen. The hot water bath area in the mixing tank is connected to the ultrapure water input port and ultrapure water output port to receive circulating ultrapure water. The tank body outlet is connected to the mixed gas-liquid coexistence output port.

[0026] In the liquid tension control method of the present invention, which can improve wafer drying efficiency, during the wafer rocking process, water molecules flow downward on the wafer plate tilted by the rocking, slowly lowering the liquid surface, and the mixture of isopropanol and hot nitrogen descends along with the liquid surface. The interfacial angle of the water molecules is increased by the rocking, and the planar included angle between the surface on which the wafer is located and the liquid surface exceeds 90 degrees, making the water molecules more likely to peel off from the wafer surface. By moving back and forth, the peeling speed of the water molecules on the wafer surface is increased and the peeling effect is strengthened. The principle can be seen in Figures 9, 10 and 11. During the oscillation of the wafer plate, the upper part of the wafer plate is a dry area, and the lower part is a wet area. Due to the Marangoni effect, a thick water film is formed in the dry area at the boundary between the liquid surface and the wafer. The surface tension formed by the isopropanol (IPA) gas phase and the ultrapure water (DIW) liquid phase is T2, and the tension of the ultrapure water (DIW) liquid phase is T1. During oscillation, the isopropanol liquid film becomes thinner due to tension and oscillation. The water molecules in the water film move sideways more quickly due to the tension, resulting in faster detachment of the water molecules. See Figure 12.

[0027] In the liquid tension control method of the present invention, which can improve wafer drying efficiency, the swinging motion of the wafer cassette D on which the wafer plate is placed is realized by a specialized swinging mechanism C, as shown in FIGS. The swing mechanism C includes a drive motor 5, a slide track 6, a slide block 7, a pivot track 8, and an L-shaped swing arm 9, the slide track 6 and the pivot track 8 are arranged in parallel, the slide track 6 is located above the pivot track 8, and the slide block 7 is attached to the slide track 6 so as to slide. The drive motor 5 drives the slide block 7 to perform reciprocating motion on the slide track 6, thereby forming a linear robot. At least two L-shaped swing arms 9 are provided, each including a first arm and a second arm arranged in parallel, a slide groove 10 is formed on the upper part of the first arm along its length, a slide wheel is attached to the slide block correspondingly, and the slide wheel is attached in the slide groove 10, the lower end of the first arm and a connection point on the pivot track are pivotally attached, and a wafer cassette receiving area 11 is provided at the lower end of the second arm.

[0028] The wafer cassette loaded with wafer plates is driven by the swing mechanism C to swing regularly, and the linear robot moves back and forth, driving the L-shaped swing arm to rotate with a fixed axis, forming an arc-shaped swing arrangement with a fixed axis, and the linear robot moves back and forth in a reciprocating manner, driving the L-shaped swing arm to perform an arc-shaped swing motion mode. The swing mechanism movement and positioning method is as follows: When the L-shaped swing arm is moved back and forth to rotate with the axis fixed, When the linear robot performs reciprocating back and forth movement, three positioning sensors are arranged to detect the corresponding swing positions: The position of swinging to the front end is positioned as A0, the center rest normal position is positioned as A1, and the position of swinging to the rear end is positioned as A2; When the wafer swings, the corresponding phase swings, corresponding to the center normal, the center rest normal position is positioned as A1, the corresponding relative phase angle of the wafer swing is 0 degrees; the position swinging to the front end is positioned as A0, the corresponding relative phase angle of the wafer swing is +θ degrees, 2°<θ<15°; The position of the swing to the rear end is positioned as A2, and the corresponding relative phase angle of the wafer swing is -θ degrees, where 2°<θ<15°.

[0029] Regarding the selection of the oscillation angle θ, if the oscillation width is less than 2°, it will not be possible to reduce the thickness of the water film and increase the liquid tension. If the oscillation width exceeds 15°, rattles will occur between the wafer plates, and the wafer plates will move and collide, resulting in damage to the wafer plates. In practical applications, the optimal drying effect can be achieved by setting the oscillation width of the included angle θ to ±2.54°. You'll benefit.

[0030] The liquid tension control method of the present invention, which can improve wafer drying efficiency, further relates to a safe control method for supplying a mixture of isopropanol and hot nitrogen, which involves determining a demand target for controlling the nitrogen mixed gas / isopropanol mixture → checking and controlling the isopropanol supply status → checking exhaust control → checking cleanliness detection control → performing mixture confirmation control → performing output confirmation corresponding to the drying operation → performing drying output.

[0031] In the liquid tension control method of the present invention, which can improve wafer drying efficiency, when performing the drying operation of raising and lowering the liquid level during the arc-shaped oscillation process, the temperature of the isopropanol liquid is controlled; if it is room temperature, it is controlled to 25 degrees and set to isopropanol room temperature control, and if it is high, it is controlled to 60 degrees (controlled to approach the critical state).The temperature of the nitrogen gas is controlled to 30 degrees and set to nitrogen room temperature control if it is room temperature, and if it is high, it is controlled to 120 degrees, and stable control is achieved by heating at high temperatures.

[0032] In the liquid tension control method of the present invention, which can improve wafer drying efficiency, the drying air flow path is improved and optimized to increase the effective drying of wafer products during the drying process and further improve drying efficiency. By modifying the paths of the isopropanol and hot nitrogen air flows, a combined result is achieved, achieving a perfect relative value expression for the ratio of drying efficiency and time. In the method of the present invention, a mixed liquid pressurization system is established in the wafer drying equipment to help improve the diffusion and distribution capabilities of IPA / N2, strengthening the Marangoni drying ability and enhancing the distribution ability of the finely divided organic solvent, which removes water molecules through tension, on the wafer surface. Furthermore, the cooperation between the special temperature maintenance unit that controls heating and the heated nitrogen generation unit, connected to the mixing tank main module, improves the control efficiency of heated nitrogen.

Claims

1. A method for controlling liquid tension that can improve wafer drying efficiency, wherein during wafer drying, residual moisture on the wafer surface is removed by using isopropanol in a gas phase substitution process with isopropanol and nitrogen using a planetary arc oscillation drying technique, the method comprising: a first step of loading a plurality of wafer plates into a wafer cassette, placing the wafer cassette on a swinging mechanism, inserting the swinging mechanism carrying the wafers into a drying groove body, connecting an upper cover dome of the drying equipment to the drying groove body, maintaining tight contact of the cabin after connection, and evacuating trace gases from the cabin; a second step of injecting ultrapure water into the drying groove and room temperature nitrogen through the top cover dome to wet the surface of the wafer plate so that the liquid level of the ultrapure water injected into the drying groove exceeds the top edge of the wafer, and continuously injecting room temperature nitrogen into the drying groove during the soaking period; After the surface of the wafer plate is completely infiltrated with ultrapure water, the injection of room temperature nitrogen is stopped. S1, injecting a mixture of isopropanol and heated nitrogen into the drying trough from the top dome using a dedicated integrated module, and draining the ultrapure water in the drying trough from the bottom at a controlled rate; and As the ultrapure water level continues to drop, the swinging mechanism is operated to swing the wafer plates in a planetary swing during the process of discharging the ultrapure water, causing each wafer plate to generate a periodic arc-shaped small-angle motion. During the swinging of the wafer plates, a tension phenomenon occurs at the contact point between the ultrapure water level and the wafer plate surface, causing the surface tension T1 of the ultrapure water phase to increase due to the tension, and the surface tension T2 formed by the isopropanol gas phase and the ultrapure water phase to decrease due to the tension. The isopropanol liquid film is pulled and thinned by the tension and the swinging, and the ultrapure water film is pulled and thinned, causing the water molecules in the thinned water film to move laterally more quickly, thereby quickly releasing the water molecules on the wafer plate. A third step S2 is performed to control the liquid tension so that the water molecules on the wafer plate are quickly released. and a fourth step of operating the rocking mechanism to continuously rock the wafer cassette until the ultrapure water is discharged and the liquid level is lower than the bottom of the wafer cassette, thereby completing the first stage of drying, checking whether it is necessary to repeat cleaning and drying, and if necessary, repeating the second and third steps to perform the second and subsequent stages of drying until the wafer plate is completely dried.

2. The method for controlling liquid tension capable of improving wafer drying efficiency as described in claim 1, characterized in that in the third step, the wafer cassette is driven by a swinging mechanism to perform a regular swinging motion within the drying groove, so that the wafer plates arranged in the wafer cassette swing regularly, and when swinging, they perform a symmetrical reciprocating motion within an inclination angle around the center of the wafer plate as an axis.

3. 3. The method of claim 2, wherein the swing mechanism includes a drive motor, a slide track, a slide block, a pivot track, and an L-shaped swing arm, the slide track and the pivot track are arranged in parallel, the slide track is located above the pivot track, and the slide block is attached to the slide track so as to slide. The drive motor drives the slide block to perform reciprocating motion on the slide track, thereby forming a linear robot. The L-shaped swing arm includes at least two parallel-arranged first and second arms, a slide groove formed in an upper portion of the first arm along its length, a slide wheel attached to the slide block corresponding to the slide groove, the slide wheel being attached in the slide groove, a lower end of the first arm and a connection point on the pivot track being pivotally attached, and a wafer cassette receiving area is provided at the lower end of the second arm.

4. 4. The method for controlling liquid tension capable of improving wafer drying efficiency according to claim 3, wherein the linear robot moves back and forth and drives the L-shaped swing arm to rotate with a fixed axis, thereby forming an arc-shaped swing mode with a fixed axis.

5. The movement and positioning method of the swing mechanism is as follows: When the L-shaped swing arm is driven to move back and forth so as to rotate around a fixed axis, three positioning sensors are arranged to detect the corresponding swing positions when the linear robot moves back and forth in a reciprocating manner: The position of swinging to the front end is located as A0, the center rest normal position is located as A1, and the position of swinging to the rear end is located as A2; When the wafer is rocking, the corresponding phase performs rocking motion, corresponding to the center normal, the center rest normal position is positioned as A1, and the corresponding relative phase included angle of the wafer rocking is 0 degree: The position of the swing to the front end is positioned as A0, and the corresponding relative phase included angle of the wafer swing is +θ degrees, where 2°<θ<15°; The method for controlling liquid tension capable of improving wafer drying efficiency as described in claim 4, characterized in that the position of the swing to the rear end is positioned as A2, and the corresponding relative phase angle of the wafer swing is -θ degrees, and 2°<θ<15°.

6. 2. The method for controlling liquid tension capable of improving wafer drying efficiency according to claim 1, wherein in the third step, the mixture of isopropanol and heated nitrogen is produced in a dedicated integrated module, transferred to the top dome, and sprayed downward into the drying groove, the isopropanol and water molecules evaporate as gas and move upward, the water molecules in liquid phase move downward by tension control, and ultrapure water is injected or discharged from the bottom of the drying groove.

7. In a third step, the dedicated integrated module structure includes an isopropanol input line, a circulating ultrapure water input line, a circulating ultrapure water output line, a heated nitrogen input line, a mixing tank body, and a mixed gas-liquid coexistence liquid output line, the mixing tank body structure includes a housing and a mixing tank, the housing is a box-shaped structure having a tank body door plate, and at least one mixing tank is provided in the housing; an isopropanol input port is provided on the front wall of the housing near the bottom, the isopropanol input port being connected to the isopropanol input pipe; one side wall of the housing is provided with an ultrapure water input port and an ultrapure water output port, which are respectively connected to the circulating ultrapure water input pipe and the circulating ultrapure water output pipe; a heated nitrogen input port is provided on the rear wall of the housing, the heated nitrogen input port being connected to the heated nitrogen input pipe; and a mixed gas-liquid mixture output port is further provided on the rear wall of the housing, the mixed gas-liquid mixture output port being connected to one end of the mixed gas-liquid mixture output pipe, the other end of which is connected to the top cover dome, thereby transporting the isopropanol and heated nitrogen mixture into the drying groove; 7. The method for controlling liquid tension capable of improving wafer drying efficiency according to claim 6, wherein the mixing tank has a cylindrical outer shape and a three-layer structure including a vortex mixing channel, a buffer reflux groove, and a hot water bath area, the vortex mixing channel being an inverted cone-shaped cavity located at the center of the mixing tank, a tank body inlet being located at the center of the bottom of the mixing tank, and a tank body outlet being located at the center of the top of the mixing tank, the tank body inlet being connected to an isopropanol input port for receiving isopropanol and inputting it into the vortex mixing channel, an upper position of the buffer reflux groove in the mixing tank being connected to the heated nitrogen input port for receiving heated nitrogen, the hot water bath area in the mixing tank being connected to the ultrapure water input port and the ultrapure water output port for receiving circulating ultrapure water, and the tank body outlet being connected to the mixed gas-liquid coexistence output port.

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