A method for controlling liquid tension that can 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 field of semiconductors, and particularly to a method for controlling liquid tension to improve wafer drying efficiency in the wafer drying process.

Background Art

[0002] In the cleaning of semiconductor wafers, drying technology is indispensable. So far, different wafer drying technologies exist for different wafer products. Wafer drying is the final finishing operation in the wet cleaning process, and it is necessary to ensure effective removal of residual moisture on the wafer surface and control of surface cleanliness. The continuous optimization and efficiency improvement of the drying method are particularly emphasized in the development of wafer cleaning equipment and technology. There are many methods applied to the wafer drying process. If effective batch drying is performed within a specified time, it will affect the batch of the entire wafer cleaning process and the effective operation of the entire operation. Therefore, a wafer drying method with effective drying efficiency is currently a particularly important part in wafer wet cleaning technology.

[0003] In the prior art, Utility Model Patent CN204257600U discloses a cleaning groove for cleaning semiconductor wafers. In the cleaning process, an external magnetic field is used to change the surface tension of the liquid, and a surface tension meter is used to monitor the surface tension value of the liquid in real time, and the monitored information is fed back to the magnetization device to control the intensity of the magnetic field, and the intensity value of the magnetic field is maintained at a predetermined value. As a result, the surface tension value of water is stabilized to a required value, meeting the process needs of wafer manufacturing. According to the above technology, in order to generate a magnetic field, a magnetization device is specially arranged in the cleaning groove, and its operation is complex. In order to stably maintain the surface tension of water, the intensity of the magnetic field must be controlled in real time, which actually increases the difficulty of operation and further affects the efficiency of cleaning and drying. Therefore, in order to realize the control of liquid tension and improve the drying efficiency of the wafer, a simpler and faster method is needed.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] Chinese Utility Model Patent No. CN204257600U [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] To improve upon the problems present in the prior art, the present invention provides a method for controlling liquid tension to improve wafer drying efficiency during the wafer drying process. As presented in the present invention, the method for controlling liquid tension to improve wafer drying efficiency during the wafer drying process effectively controls the liquid tension and, through comprehensive control, enables the rapid removal of water molecules from the wafer, thereby completing the rapid drying of the wafer. [Means for solving the problem]

[0006] To achieve the above-mentioned objectives of the invention, 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 when drying a wafer, residual moisture on the wafer surface is removed using isopropanol in the gas phase displacement process with isopropanol and nitrogen using planetary arc-shaped oscillating drying technology, and the method is The first step involves stacking multiple wafer plates in a wafer cassette, placing the wafer cassette in a rocking mechanism, placing the rocking mechanism carrying the wafers into the drying groove, connecting the upper dome of the drying equipment to the drying groove to maintain airtightness of the cabin after connection, and exhausting trace amounts of gas from inside the cabin. Dry groove body DIW In addition to injecting the substance, room-temperature nitrogen was injected through the top dome and then into the drying groove body. DIW The second step involves moistening 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 immersion period. DIW After the surface penetration of the wafer plate by the agent is complete, the injection of room-temperature nitrogen is stopped. Using a dedicated integrated module, a mixture of isopropanol and heated nitrogen is injected from the top dome into the drying groove body, DIWS1 discharges from the bottom to control the speed, DIW As the liquid level continues to fall, DIW During the discharge process, the oscillating mechanism is operated to carry the wafer plates and form a planetary oscillating motion, thereby generating a small, arc-shaped periodic small-angle motion in each wafer plate, and during the oscillating process of the wafer plates, DIW A tensile phenomenon occurs at the point of contact between the liquid surface and the wafer surface. DIW The tension T1 of the liquid phase increases due to tension, and the isopropanol gas phase DIW The surface tension T2 formed from the liquid phase decreases due to tension, and the isopropanol liquid film thins out as it is stretched by tension and oscillation. DIW The third step involves performing S2, which controls the liquid tension so that the water film becomes thinner when stretched, the water molecules within the thinned water film move laterally more quickly, and the water molecules on the wafer plate detach more quickly. DIW The process includes a fourth step in which the oscillating mechanism is operated to continuously oscillate 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 the washing and drying process, and if necessary, repeating the second and third steps to perform the second and subsequent drying stages until the wafer plate is completely dried.

[0007] In the third step, the wafer cassette oscillates regularly within the drying groove by the drive of the oscillating mechanism, causing the wafer plates arranged within the wafer cassette to oscillate regularly and reciprocate symmetrically within the inclination angle with the center of the wafer plate as the axis.

[0008] In further structural design, the rocking mechanism includes a drive motor, a slide track, a slide block, an pivot track, and an L-shaped rocking arm, wherein the slide track and the pivot track are arranged parallel to each other, the slide track is located above the pivot track, the slide block is mounted on the slide track so as to slide, and the drive motor drives the slide block to perform a reciprocating motion on the slide track, thereby forming a linear robot; the L-shaped rocking arm includes at least two, a first arm and a second arm arranged parallel to each other, the upper part of the first arm is provided with a slide groove along its length, the slide block is fitted with a corresponding slide ring, the slide ring is mounted within the slide groove, the lower end of the first arm and the connection point on the pivot track are pivotally mounted, and the lower end of the second arm is provided with a wafer cassette receiving area.

[0009] In further structural design, the linear robot moves back and forth, driving the L-shaped oscillating arm to perform rotations with a fixed axis, thereby forming an arc-shaped oscillating mode with a fixed axis.

[0010] In the third step above, during the wafer oscillation process, as the wafer is tilted by the oscillation, water molecules flow downward, slowly lowering the liquid surface. The mixture of isopropanol and hot nitrogen also descends along with the liquid surface. The interface angle of the water molecules is increased by the oscillation, and the plane-to-plane angle between the surface where the wafer is located and the liquid surface exceeds 90 degrees. As a result, water molecules easily detach from the wafer surface. By operating back and forth, the rate of detachment of water molecules from the wafer surface increases, and the detachment effect becomes stronger. During the wafer oscillation process, the upper part of the wafer is a dry region, and the lower part is a immersion region. Due to the Marangoni effect, a thick water film is formed in the dry region at the boundary between the liquid surface and the wafer, and the isopropanol gas phase and DIW The surface tension formed from the liquid phase is T2, and the tension of the DIW liquid phase is T1. When oscillating, the isopropanol liquid film thins due to the tension and oscillating motion, and the water molecules within the water film move laterally more quickly due to the tension, resulting in faster detachment of water molecules.

[0011] In further structural design, the movement and positioning method of the rocking mechanism is as follows: When an L-shaped oscillating arm is driven by moving it back and forth to perform rotation with a fixed axis, and the linear robot performs reciprocating back and forth movement, three positioning sensors are arranged to detect the corresponding oscillating position. The position where the movement is directed towards the front end is positioned as A0, the position of the center's resting normal is positioned as A1, and the position where the movement is directed towards the rear end is positioned as A2. When the wafer oscillates, the corresponding phase performs the oscillating motion, corresponding to the center normal. The center stationary normal position is positioned as A1, and the corresponding relative phase angle of the wafer oscillation is 0 degrees. The position where the wafer oscillates towards the front is positioned as A0, and the corresponding relative phase angle of the wafer oscillation is +θ degrees, where 2° < θ < 15°. The position where the wafer oscillates toward the rear end is positioned as A2, and the corresponding relative phase angle of the wafer oscillation is -θ degrees, where 2° < θ < 15°.

[0012] In the further structural design, in the third step, the mixture of isopropanol and heated nitrogen is produced from a dedicated integrated module, transmitted to the upper lid dome, and sprayed downward into the drying groove body, the isopropanol and water molecules volatilize as a gas phase and move upward, and the water molecules in liquid phase move downward under tension control. DIW It is injected or discharged from the bottom of the drying groove.

[0013] In further structural design, a dedicated integrated modular structure is used for the isopropanol input pipeline and circulation. DIW Input conduit via circulation DIW Output pipeline, heated nitrogen input pipeline, mixing tank body, and mixed gas and liquid. coexistenceIt includes an output pipeline. The mixing tank body structure includes a housing and a mixing tank. The housing is a box-shaped structure with a tank body door plate. At least one mixing tank is provided inside the housing. An isopropanol input port is provided at a position close to the bottom of the front side wall of the housing. The isopropanol input port is connected to the isopropanol input pipeline. On one side wall of the housing, there are DIW input ports respectively connected corresponding to the DIW circulation input pipeline and the DIW circulation output pipeline, D IW and an output port is provided. A heated nitrogen input port is provided on the rear side wall of the housing. The heated nitrogen input port is connected to the heated nitrogen input pipeline. A mixed gas-liquid coexistence body output port is further provided on the rear side wall of the housing. The mixed gas-liquid coexistence body output port is connected to one end of the mixed gas-liquid coexistence output pipeline. The other end of the mixed gas-liquid coexistence output pipeline communicates with the upper cover dome, so as to transport the mixture of isopropanol and heated nitrogen into the drying groove body. The outer shape of the mixing tank is a cylinder, and the inside of the mixing tank is a three-layer structure including a vortex mixing path, a buffer reflux groove and a warm water bath area. The vortex mixing path is an inverted conical cavity provided at the center of the mixing tank. A tank body inlet is provided at the center position of the bottom of the mixing tank, and a tank body outlet is provided at the center position of the top part. The tank body inlet communicates with the isopropanol input port to receive isopropanol and input it into the vortex mixing path. The upper position of the buffer reflux groove in the mixing tank communicates with the heated nitrogen input port to receive heated nitrogen. The warm water bath area in the mixing tank communicates with the DIW input port and DIW output port to receive the DIW circulation. The tank body outlet communicates with the mixed gas-liquid coexistence body output port.

[0014] In the method for controlling liquid tension capable of improving wafer drying efficiency according to the present invention, further regarding a safe control method for supplying a mixture of isopropanol and hot nitrogen, determine the demand target for controlling the nitrogen mixed gas / isopropanol mixture → check and control the isopropanol supply situation → check the exhaust control → check the cleanliness detection control → perform the mixing confirmation control → execute the output confirmation corresponding to the drying operation → execute the drying output.

[0015] In the method for controlling liquid tension capable of improving wafer drying efficiency according to the present invention, during the process of arcuate oscillation, when the liquid surface rises and falls to perform the drying operation, control the temperature of the isopropanol liquid. If it is at room temperature, control it to 25 degrees and set it for isopropanol room temperature control. If it is at high temperature, control it to 60 degrees (control it to approach the critical state). Regarding the temperature control of nitrogen gas, if it is at room temperature, control it to 30 degrees and set it for nitrogen room temperature control. If it is at high temperature, control it to 120 degrees. When at high temperature, achieve stable control by heating.

Effect of the Invention

[0016] Based on the above technical solution, the ship pressure pipeline chemical filling system according to the present invention obtains the following technical effects through practical application: 1. The method for controlling liquid tension capable of improving wafer drying efficiency according to the present invention realizes the control of liquid tension through two synchronous operations to effectively complete the drying operation of the wafer plate. First: Input isopropanol and heated nitrogen using a dedicated integrated module, thereby improving the temperature and purity of isopropanol. Due to the characteristic that the liquid tension of high-purity isopropanol is small, it accelerates the separation of moisture on the wafer plate; Second: The rocking mechanism forms a small-angle rocking of the wafer plate, DIW and the angle with the wafer plate changes regularly, changing the magnitude of the liquid tension at both ends of the interface, thinning the DIW water film adhering to the wafer plate, enabling water molecules to quickly detach from the surface of the wafer plate and greatly improving the drying efficiency. 2. In the method for controlling liquid tension capable of improving wafer drying efficiency according to the present invention, the rocking mechanism When the wafer cassette is shaken, the affected wafer plate tilts, and water molecules flow downwards. DIW The liquid level slowly lowers, and the mixture of isopropanol and hot nitrogen DIW As the water descends towards the liquid surface, the interface angle of the water molecules is increased by the oscillation, and the plane-to-plane angle between the surface on which the wafer is located and the liquid surface exceeds 90 degrees. As a result, the water film adhering to the wafer surface becomes thinner, and the water molecules within the water film are more easily detached from the wafer surface. The reciprocating oscillation operation increases the rate at which water molecules detach from the wafer surface, thereby enhancing the detachment effect. 3. In the liquid tension control method according to the present invention, by improving and optimizing the dry air flow path... By increasing the drying speed of the wafer product during the drying process, improving drying efficiency, and modifying the paths of isopropanol and thermal nitrogen airflow, a combined result is achieved, improving drying efficiency and achieving an optimal drying efficiency ratio in the same amount of time. 4. In the liquid tension control method according to the present invention, by designing a dedicated integrated module By providing isopropanol and heated nitrogen and constructing a mixed liquid pressurization system, the diffusion and distribution capabilities of IPA / N2 are enhanced, strengthening the Marangoni drying capability and improving the wafer surface distribution capability of the finely milled organic solvent that removes water molecules by tension. Specifically, in the integrated module, a temperature-holding special unit that controls heating and a heated nitrogen-derived unit connected to the main mixing tank module cooperate with each other to improve the control efficiency of heated nitrogen and stably achieve overall heating and auxiliary heat retention of nitrogen. [Brief explanation of the drawing]

[0017] [Figure 1] This is a schematic diagram of the wafer drying process in the liquid tension control method for improving wafer drying efficiency according to the present invention. [Figure 2] This is a schematic diagram of the arrangement of a wafer cassette in a drying apparatus, in a liquid tension control method that can improve wafer drying efficiency according to the present invention. [Figure 3] This is a schematic diagram of the initial state of the drying process in a method for controlling liquid tension that can improve wafer drying efficiency according to the present invention. [Figure 4] This is a schematic diagram of an intermediate state in the drying process, in the liquid tension control method for improving wafer drying efficiency according to the present invention. [Figure 5] This is a schematic diagram of the final state of the drying process in a method for controlling liquid tension that can improve wafer drying efficiency according to the present invention. [Figure 6] This is a schematic diagram showing the mounting state of the oscillating device and wafer cassette in the liquid tension control method for improving wafer drying efficiency according to the present invention. [Figure 7] This is a schematic diagram of the structure of an oscillating device in a liquid tension control method that can improve wafer drying efficiency according to the present invention. [Figure 8] This is a schematic diagram of the oscillation state of a wafer cassette in the liquid tension control method for improving wafer drying efficiency according to the present invention. [Figure 9] This is a schematic diagram illustrating different states of a wafer when the wafer cassette is oscillating, in a liquid tension control method for improving wafer drying efficiency according to the present invention. [Figure 10] This is a schematic diagram of the connection point between the liquid surface and the wafer in a state in which the wafer is oscillating and tilting, in a liquid tension control method that can improve wafer drying efficiency according to the present invention. [Figure 11] This diagram shows a schematic representation of the change in liquid tension in a method for controlling liquid tension that can improve wafer drying efficiency, where the wafer is oscillating and tilted. [Figure 12] This is a schematic diagram illustrating the principle of a liquid tension control method that can improve wafer drying efficiency, in which the water flow increases due to a change in liquid tension. [Figure 13] This is a schematic diagram of the structure and pipeline connections of a dedicated integrated module in a liquid tension control method that can improve wafer drying efficiency according to the present invention. [Modes for carrying out the invention]

[0018] The present invention will be described in detail below by combining drawings and specific embodiments to provide a clearer understanding of its structure and working methods, but this will not limit the scope of protection of the present invention.

[0019] This invention relates to the realization of a drying technology that can be coupled with batch-type wafer wet cleaning equipment, and focuses on transforming the process principles involved in drying wafers. The drying process of this invention is used in the process of gas-phase displacement of the organic solvent isopropanol (IPA) and nitrogen (N2), IPA will further optimize the design of the method for removing residual moisture from the wafer surface. This drying method corresponds to the traditional Marangoni wafer drying technology and employs a two-phase shift movement by isopropanol solvent and water molecules to exert tension diffusion and vertical pulling action, 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 technology, the present invention aims to remove residual moisture from the wafer surface using isopropanol (IPA) in a planetary arc-shaped oscillating drying technique, in which the ultrapure water liquid phase is replaced by a gas phase of the organic solvent isopropanol and heated nitrogen during the wafer drying process. The present invention is applied to wafer drying equipment and specifically includes the following steps: Step 1: Multiple wafers are loaded into a wafer cassette, the wafer cassette is placed in a rocking mechanism, the rocking mechanism carrying the wafer cassette is placed inside the drying groove, the top dome of the drying equipment is coupled to the drying groove to maintain airtightness of the cabin after coupling, and trace amounts of gas inside the cabin are exhausted. In this step, by assembling the wafers and placing them in the wafer cassette, simultaneous cleaning and drying of multiple wafers is achieved, improving efficiency. The wafer cassette is placed in a specialized rocking mechanism, and a part of the rocking mechanism is inserted into the drying groove to create a micro-vacuum environment inside the drying groove, ensuring that the cleaning and drying of the wafers takes place in a closed and safe environment. Step 2: Ultrapure water is injected into the drying grooves, and room temperature nitrogen is injected through the top dome to moisten the wafer surface so that the liquid level of the ultrapure water injected into the drying grooves exceeds the uppermost edge of the wafer. Room temperature nitrogen is continuously injected into the drying grooves during the immersion period. In this step, injecting room temperature nitrogen reduces the oxygen content in the drying groove space as much as possible, and further reduces the effect of oxidation on the wafer surface. Step 3: After the surface immersion of the wafer plate with ultrapure water is complete, stop injecting room temperature nitrogen. S1, a mixture of isopropanol and heated nitrogen is injected into the drying groove body from the top dome using a dedicated integrated module, and ultrapure water is discharged from the bottom of the drying groove body in a manner that controls the rate. As the liquid level of the ultrapure water continuously decreases, the oscillation mechanism is operated to carry the wafer plates during the ultrapure water discharge process to form planetary oscillations, thereby generating arc-shaped periodic small-angle motions in each wafer plate. During the oscillation process of the wafer plates, a tensile phenomenon occurs at the contact point between the ultrapure water liquid level and the wafer plate surface. The tension T1 of the ultrapure water liquid phase increases due to the tension, and the surface tension T2 formed from the isopropanol gas phase and the ultrapure water liquid phase decreases due to the tension. The isopropanol liquid film is thinned by being pulled by the tension and oscillation, and the ultrapure water film is thinned by the tension. The water molecules in the thinned water film move laterally more quickly, and liquid tension is controlled S2 to quickly detach the water molecules from the wafer plate.

[0021] At the heart of liquid tension control, this step removes water molecules remaining in the ultrapure water from the wafer surface from two sides: 1) Inject a mixture of heated nitrogen and isopropanol IPA to purify the isopropanol to the maximum extent, thereby reducing the liquid tension at the contact surface between isopropanol and ultrapure water, while the heated nitrogen further evaporates water molecules. 2) During the descent of the ultrapure water surface, the wafer is continuously held to oscillate regularly and periodically by driving a oscillating mechanism. This stretches and thins the water film at the contact point between the ultrapure water and the wafer. Due to the action of liquid tension, water molecules in the thinned water film on the wafer surface rapidly concentrate along the wafer and detach quickly from the wafer surface, achieving overall control of liquid tension and accelerating the drying of the wafer.

[0022] Step 4: Complete the first stage of drying by operating the rocking mechanism to continuously rock the wafer cassette until the ultrapure water is drained and the liquid level is lower than the wafer cassette. Check if it is necessary to repeat the washing and drying process, and if necessary, repeat steps 2 and 3 to perform the second and subsequent drying stages until the wafer is completely dried.

[0023] In the present invention, a method for controlling liquid tension that can improve wafer drying efficiency, as shown in Figures 3, 4, and 5, during the drying process, a mixture 1 of isopropanol and heated nitrogen is injected into the drying groove from location A in Figure 2. The mixture 1 is sprayed downwards, the isopropanol and water molecule gas phase 2 volatilizes and moves upwards, and the water molecule liquid phase 3 moves downwards due to tension control. At location B in Figure 2, liquid 4 is discharged from the bottom of the drying groove, and the discharged liquid is mainly ultrapure water. As shown in Figure 2, during the liquid discharge process, the wafer cassette oscillates regularly by the drive of the oscillating mechanism, causing the wafer plates arranged in the wafer cassette to oscillate regularly and perform symmetrical reciprocating motion within the tilt angle with the wafer center as the axis. For specific motion patterns, please refer to Figures 7 and 8.

[0024] The mixture of isopropanol and heated nitrogen is produced from a dedicated accumulation module, which produces the mixture of isopropanol and heated nitrogen and transmits it to the upper lid dome, and further sprays it downward into the drying groove body. Within the drying groove body, the isopropanol and water molecules volatilize as a gas phase and move upward, while the liquid phase of water molecules moves downward under tension control, and the liquid containing ultrapure water is injected or discharged from the bottom of the drying groove body.

[0025] As shown in Figure 13, the dedicated integrated module structure includes an isopropanol input line 16, a circulating ultrapure water input line, a circulating ultrapure water output line, a heated nitrogen input line 17, a mixing tank body 15, and a gas-liquid mixture after mixing. coexistence The structure of the mixing tank body 15 includes an output pipeline 18, and the structure of the mixing tank body 15 includes 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 is provided inside the housing. An isopropanol input port is provided on the front side wall of the housing, near the bottom, and the isopropanol input port is connected to the isopropanol input pipeline 16, and an ultrapure water input port and an ultrapure water output port are provided on one side wall of the housing, connected to the circulating ultrapure water input pipeline and the circulating ultrapure water output pipeline, respectively. A heated nitrogen input port is provided on the rear side wall of the housing, and the heated nitrogen input port is connected to the heated nitrogen input pipeline 17, and an output port for the mixed gas-liquid coexistence is further provided on the rear side wall of the housing, and the output port for the mixed gas-liquid coexistence is connected to the mixed gas-liquid coexistence coexistence It is connected to one end of the output pipe 18, and the mixed gas and liquid coexistenceThe other end of the output conduit 18 communicates with the upper cover dome 13, thereby transporting a mixture of isopropanol and heated nitrogen into the drying groove body 12. A wafer cassette is placed on the oscillating mechanism 14, and the wafer cassette is positioned inside the drying groove body 12. The mixing tank has a cylindrical shape externally, and its interior has 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 conical cavity located in the center of the mixing tank. The tank body inlet is located at the center of the bottom of the mixing tank, and the tank body outlet is located at the center of the top. The tank body inlet communicates with an isopropanol input port, receiving isopropanol and inputting it into the vortex mixing channel. The upper part of the buffer reflux groove in the mixing tank communicates with a heated nitrogen input port, receiving heated nitrogen. The hot water bath area in the mixing tank communicates with an ultrapure water input port and an ultrapure water output port, receiving circulating ultrapure water. The tank body outlet communicates with the output port of the mixed gas-liquid coexistence.

[0026] In the present invention, a method for controlling liquid tension that can improve wafer drying efficiency, during the wafer oscillating process, water molecules flow downward on the wafer plate tilted by the oscillating motion, causing the liquid surface to slowly descend. The mixture of isopropanol and thermal nitrogen descends along with the liquid surface, the interface angle of the water molecules is increased by the oscillating motion, the plane-binding angle between the surface on which the wafer is located and the liquid surface exceeds 90 degrees, making it easier for water molecules to detach from the wafer surface. By performing the operation back and forth, the detachment rate of water molecules on the wafer surface increases, and the detachment effect becomes stronger. For the principle, please refer to Figures 9, 10, and 11. During the oscillation process of the wafer, the upper part of the wafer is a dry region, and the lower part is a immersion region. Due to the Marangoni effect, a thick water film is formed in the dry region at the boundary between the liquid surface and the wafer. The surface tension formed from 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. When oscillating, the isopropanol liquid film thins due to tension and pulling from the oscillation, and the water molecules within the water film move laterally more quickly due to tension, resulting in faster detachment of water molecules. See Figure 12.

[0027] In the liquid tension control method of the present invention, which can improve wafer drying efficiency, the oscillating motion of the wafer cassette D on which the wafer plate is placed is realized by a specialized oscillating mechanism C, as shown in Figures 6 and 7. The rocking mechanism C includes a drive motor 5, a slide track 6, a slide block 7, an pivot track 8, and an L-shaped rocking 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, the slide block 7 is mounted on the slide track 6 so as to slide, and the drive motor 5 drives the slide block 7 to reciprocate along the slide track 6, thereby forming a linear robot. The L-shaped rocking arm 9 has at least two parts, including a first arm and a second arm arranged in parallel, the upper part of the first arm has a slide groove 10 along its length, the slide block has a corresponding slide ring attached, the slide ring is mounted in the slide groove 10, the lower end of the first arm and the connection point on the pivot track are pivotally mounted, and the lower end of the second arm has a wafer cassette receiving area 11.

[0028] Driven by the oscillating mechanism C, the wafer cassette on which the wafer plates are loaded oscillates regularly, and the linear robot moves it back and forth, driving the L-shaped oscillating arm to perform rotation with a fixed axis, thereby forming an arc-shaped oscillating arrangement with a fixed axis. The linear robot's reciprocating back and forth movement drives the L-shaped oscillating arm to perform the arc-shaped oscillating motion mode. The movement and positioning method of the oscillating mechanism is as follows: When driving an L-shaped swing arm by moving it back and forth to perform rotation with a fixed axis: When the linear robot performs a reciprocating forward and backward movement, three positioning sensors are arranged to detect the corresponding swing position: The position where the movement is directed towards the front end is positioned as A0, the position of the center's resting normal is positioned as A1, and the position where the movement is directed towards the rear end is positioned as A2; When the wafer oscillates, the corresponding phase performs the oscillating motion, corresponding to the center normal. The center stationary normal position is positioned as A1, and the corresponding relative phase angle of the wafer oscillation is 0 degrees. The position where the wafer oscillates towards the front is positioned as A0, and the corresponding relative phase angle of the wafer oscillation is +θ degrees, where 2° < θ < 15°. The position where the wafer oscillates toward the rear end is positioned as A2, and the corresponding relative phase angle of the wafer oscillation is -θ degrees, where 2° < θ < 15°.

[0029] Regarding the selection of the oscillation angle θ, if the oscillation range is less than 2°, the effect of reducing the water film thickness and increasing liquid tension cannot be achieved. If the oscillation range exceeds 15°, rattle occurs between the wafer plates, and further, the position shifts, leading to collisions and damage to the wafer plates. In actual applications, the optimal drying effect is achieved by setting the possible oscillation range angle θ to ±2.54°. It's advantageous.

[0030] The present invention relates to a liquid tension control method capable of improving wafer drying efficiency, and further to the following safe control method for supplying a mixture of isopropanol and thermal nitrogen: Determine the demand target for controlling the nitrogen mixed gas / isopropanol mixture → Check and control the isopropanol supply status → Check the exhaust control → Check the cleanliness detection control → Perform a mixing confirmation control → Perform an output confirmation in accordance with the drying operation → Execute the drying output.

[0031] In the present invention, a liquid tension control method capable of improving wafer drying efficiency, when performing a 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 at room temperature, it is controlled to 25 degrees Celsius, setting it to isopropanol room temperature control. If it is at a high temperature, it is controlled to 60 degrees Celsius (controlled to approach the critical state). Regarding the temperature control of the nitrogen gas, if it is at room temperature, it is controlled to 30 degrees Celsius, setting it to nitrogen room temperature control. If it is at a high temperature, it is controlled to 120 degrees Celsius, achieving stable control by heating at high temperatures.

[0032] The present invention provides a liquid tension control method capable of improving wafer drying efficiency, further enhancing drying efficiency by improving and optimizing the drying airflow path to increase the effective drying of wafer products during the drying process. By modifying the paths of isopropanol and thermal nitrogen airflow, a combined result is achieved, realizing a perfect relative expression of the ratio of drying efficiency to time. In the method of the present invention, by constructing a mixed liquid pressurization system in the wafer drying equipment, the diffusion and distribution ability of IPA / N2 is improved, thereby enhancing the Marangoni drying ability and strengthening the wafer surface distribution ability of the refined organic solvent that removes water molecules by tension. Furthermore, the temperature-holding special unit that performs heating control and the heated nitrogen-derived unit, both connected to the mixing tank main module, cooperate with each other to improve the control efficiency of heated nitrogen.

Claims

1. A method for controlling liquid tension that can improve wafer drying efficiency, wherein when drying a wafer, residual moisture on the wafer surface is removed using isopropanol in the gas phase displacement process with isopropanol and nitrogen by planetary arc-shaped oscillating drying technology, and this method is The first step involves stacking multiple wafer plates in a wafer cassette, placing the wafer cassette in a rocking mechanism, placing the rocking mechanism carrying the wafers into the drying groove, connecting the upper lid dome of the drying equipment to the drying groove to maintain airtightness of the cabin after connection, and exhausting trace amounts of gas from inside the cabin. The second step involves injecting DIW into the drying groove and simultaneously injecting room-temperature nitrogen through the top dome to moisten the wafer surface so that the liquid level of the DIW injected into the drying groove exceeds the uppermost edge of the wafer, and continuously injecting room-temperature nitrogen into the drying groove during the immersion period. After the surface penetration of the wafer plate by DIW is complete, the injection of room temperature nitrogen is stopped. S1, a mixture of isopropanol and heated nitrogen is injected into the drying groove body from the top dome using a dedicated integration module, and the DIW inside the drying groove body is discharged from the bottom in a manner that controls the speed. As the liquid level of the DIW continuously decreases, the third step involves operating the oscillation mechanism to carry the wafer plates during the DIW discharge process to form planetary oscillations, thereby generating arc-shaped periodic small-angle motions in each wafer plate. During the oscillation process of the wafer plates, a tensile phenomenon occurs at the contact point between the DIW liquid level and the wafer plate surface. The surface tension T1 of the DIW liquid phase increases due to the tension, and the surface tension T2 formed from the isopropanol gas phase and the DIW liquid phase decreases due to the tension. The isopropanol liquid film thins due to being pulled by the tension and oscillation, and the DIW water film thins due to being pulled. The water molecules in the thinned water film move laterally more quickly, and the liquid tension is controlled in step S2 to rapidly detach the water molecules from the wafer plate. A method for controlling liquid tension that can improve wafer drying efficiency, characterized by including a fourth step of operating a rocking mechanism to continuously rock the wafer cassette until the DIW is discharged and the liquid level is lower than the bottom of the wafer cassette, completing the first stage of drying, checking whether it is necessary to repeat washing and drying, and if necessary, repeating the second and third steps to perform the second and subsequent drying stages until the wafer plate is completely dried.

2. In the third step, the wafer cassette oscillates regularly within the drying groove by driving the oscillating mechanism, causing the wafer plates arranged within the wafer cassette to oscillate regularly, and when oscillating, they perform symmetrical reciprocating motion within an inclination angle with respect to the center of the wafer plates, as described in claim 1, which is a method for controlling liquid tension that can improve wafer drying efficiency.

3. The oscillating mechanism includes a drive motor, a slide track, a slide block, an pivot track, and an L-shaped oscillating arm, wherein the slide track and the pivot track are arranged in parallel, the slide track is located above the pivot track, the slide block is mounted on the slide track so as to slide, the drive motor drives the slide block to perform a reciprocating motion on the slide track, thereby forming a linear robot, and the L-shaped oscillating arm includes at least two, a first arm and a second arm arranged in parallel, a slide groove is provided on the upper part of the first arm along its length, a corresponding slide ring is attached to the slide block, the slide ring is mounted in the slide groove, the lower end of the first arm and a connection point on the pivot track are pivotally attached, and a wafer cassette receiving area is provided on the lower end of the second arm, characterized in that a liquid tension control method capable of improving wafer drying efficiency is provided according to claim 2.

4. The liquid tension control method for improving wafer drying efficiency according to claim 3, characterized in that the linear robot moves back and forth and drives an L-shaped oscillating arm to perform rotation in which the axis is fixed, thereby forming an arc-shaped oscillating mode in which the axis is fixed.

5. The movement and positioning method of the aforementioned rocking mechanism is as follows: When driving an L-shaped swing arm by moving it back and forth to perform rotation with a fixed axis. When the linear robot performs a reciprocating forward and backward movement, three positioning sensors are arranged to detect the corresponding swing position: The position where the movement is directed towards the front end is positioned as A0, the position of the center's resting normal is positioned as A1, and the position where the movement is directed towards the rear end is positioned as A2; When the wafer oscillates, the corresponding phase performs the oscillating motion, corresponding to the center normal. The center stationary normal position is positioned as A1, and the corresponding relative phase angle of the wafer oscillation is 0 degrees. The position where the wafer oscillates towards the front is positioned as A0, and the corresponding relative phase angle of the wafer oscillation is +θ degrees, where 2° < θ < 15°. The liquid tension control method for improving wafer drying efficiency according to claim 4, characterized in that the position for oscillation toward the rear end is positioned as A2, the corresponding relative phase angle of wafer oscillation is -θ degrees, and 2° < θ < 15°.

6. In the third step, the mixture of isopropanol and heated nitrogen is produced from a dedicated integrated module, transmitted to the upper lid dome and sprayed downward into the drying groove body, the isopropanol and water molecules volatilize as a gas phase and move upward, the water molecule liquid phase moves downward under tension control, and the DIW is injected or discharged from the bottom of the drying groove body, characterized in that a liquid tension control method capable of improving wafer drying efficiency is described in claim 1.

7. In the third step, the dedicated integrated module structure includes an isopropanol input pipeline, a circulating DIW input pipeline, a circulating DIW output pipeline, a heated nitrogen input pipeline, a mixing tank body, and an output pipeline for the mixed gas-liquid coexistence, 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 inside the housing. An isopropanol input port is provided on the front wall of the housing near the bottom, and this isopropanol input port is connected to the isopropanol input pipeline. A DIW input port and a DIW output port are provided on one side wall of the housing, corresponding to the circulating DIW input pipeline and the circulating DIW output pipeline, respectively. A heated nitrogen input port is provided on the rear wall of the housing, and this heated nitrogen input port is connected to the heated nitrogen input pipeline. A mixed gas-liquid coexistence output port is further provided on the rear wall of the housing, and this mixed gas-liquid coexistence output port is connected to one end of the mixed gas-liquid coexistence output pipeline. The other end of the mixed gas-liquid coexistence output pipeline communicates with the top dome, thereby transporting the mixture of isopropanol and heated nitrogen into the drying groove body. The mixing tank has a cylindrical shape, and its interior has 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 conical cavity located in the center of the mixing tank. A tank body inlet is provided at the center of the bottom of the mixing tank, and a tank body outlet is provided at the center of the top. The tank body inlet communicates with an isopropanol input port to receive isopropanol and input it into the vortex mixing channel. The upper part of the buffer reflux groove in the mixing tank communicates with a heated nitrogen input port to receive heated nitrogen. The hot water bath area in the mixing tank communicates with a DIW input port and a DIW output port to receive circulating DIW. The tank body outlet communicates with an output port for the mixed gas-liquid coexistence, as described in claim 6, for controlling liquid tension that can improve wafer drying efficiency.

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