Liquid injection system for wafer cleaning equipment

Abstract

【Problem】To provide a liquid injection system for a wafer cleaning apparatus that improves the quality and efficiency of wafer cleaning. 【Solution】The liquid injection system of the wafer cleaning apparatus of the present invention includes a pickling tank, a sulfuric acid supply source, a hydrogen peroxide supply source, a first mixing device, a second mixing device, and a feedback control board. The first mixing device and the second mixing device each include a mixing pipe, a plurality of mixing screws installed in the mixing pipe, and a heater covered outside the mixing pipe. By adopting a step-by-step mixing method, the present invention realizes sufficient mixing of sulfuric acid and hydrogen peroxide, achieves accurate temperature control, and ensures complete reaction of the mixed solution. Thereby, the mixed solution supplied to the pickling tank meets the cleaning requirements, and the quality and efficiency of wafer cleaning can be improved.

Description

[Technical Field]

[0001] The present invention relates to a wafer cleaning process, which belongs to the field of wafer processing technology, and more particularly to a liquid injection system for a wafer cleaning apparatus. [Background technology]

[0002] In the cleaning process of semiconductor wafers, tank-type cleaning equipment is widely used as a dedicated cleaning device using chemicals. Up until now, solutions suitable for different cleaning processes have been developed according to the use of various wafer products.

[0003] Common cleaning processes, such as film stripping, resist stripping, organic cleaning, and removal of metal surface structures and metal residues, use activated SPM (sulfuric acid-hydrogen peroxide mixture), which is made by mixing sulfuric acid (H2SO4), hydrogen peroxide (H2O2), and ultrapure water. These are mixed at specified concentration ratios and used as various activated mixed solutions, such as DSP+, which adds SPM and ozonated water. These solutions are used to clean contaminants adhering to wafer substrates.

[0004] Active SPM mixed solutions have a corrosive effect on semiconductor materials such as silicon (Si), silicon carbide (SiC), gallium nitride (GaN), and gallium arsenide (GaAs), as well as common metals and organic materials with relatively loose molecular structures, thereby cleaning, etching, and removing them. Therefore, they are frequently used in the cleaning process of semiconductor wafers.

[0005] In the SPM pickling process using tank-type equipment, corresponding piping routes are used to supply sulfuric acid (H2SO4), hydrogen peroxide (H2O2), and ultrapure water, which are then injected into each supply pipe, then passed through transport pipes, circulation pipes, circulation pumps, filters, mixers, temporary storage tanks, and discharge pipes before finally being sent to the corresponding pickling tanks, where they are prepared for cleaning.

[0006] However, this transportation process has drawbacks such as uneven mixing, large temperature control errors, and insufficient reaction. These problems pose fatal flaws to the SPM pickling process in tank-type equipment, causing a decrease in cleaning performance. Summary of the Invention [Problem to be solved by the invention]

[0007] The technical problem to be solved by the present invention is to provide a liquid injection system for a wafer cleaning apparatus that has uniform mixing, precise temperature control, and sufficient response, thereby overcoming the drawbacks of the prior art. [Means for solving the problem]

[0008] In order to solve the above technical problems, the present invention employs the following technical means.

[0009] The liquid injection system of the wafer cleaning apparatus includes an acid pickling tank, a sulfuric acid supply source, and a hydrogen peroxide supply source; The system further includes a first mixing device, a second mixing device, and a feedback control board.

[0010] The first mixing device and the second mixing device each include a mixing pipe, a plurality of mixing screws disposed within the mixing pipe, and a heater enclosed outside the mixing pipe.

[0011] The two main input ports of the first mixer are connected to a sulfuric acid source and a hydrogen peroxide source via a main sulfuric acid line and a main hydrogen peroxide line, respectively. The main input port of the second mixer is connected to a main output port of the first mixer, and the two sub input ports of the second mixer are connected to a sulfuric acid source and a hydrogen peroxide source via an adjusting sulfuric acid line and an adjusting hydrogen peroxide line, respectively. The main output port of the second mixer is connected to a pickling tank.

[0012] The main output ports of the first mixer and the second mixer are each equipped with a thermometer and an oxygen concentration meter, and the main sulfuric acid pipe, main hydrogen peroxide pipe, adjusting sulfuric acid pipe, and adjusting hydrogen peroxide pipe are each equipped with a flow valve.

[0013] The heater, the thermometer, the oximeter, and the flow valve are all electrically connected to a feedback control board.

[0014] In a specific embodiment of the present invention, a third mixing device and a cooling circulation device are also included. The third mixing device includes a mixing pipe, a plurality of mixing screws installed in the mixing pipe, and a heater and a cooling channel enclosed on the outside of the mixing pipe. The main inlet of the third mixing device is connected to the main outlet of the second mixing device, and the main outlet of the third mixing device is connected to the pickling tank.

[0015] The cooling channel is provided with an inlet and an outlet for the cooling liquid, which are respectively connected to the liquid outlet and the liquid inlet of a cooling circulation device via a cooling pipe. The cooling circulation device is electrically connected to a feedback control board, and a thermometer and an oxygen concentration meter are also electrically connected to the feedback control board at the main output port of the third mixer.

[0016] In a specific embodiment of the present invention, the system further includes an auxiliary heater electrically connected to the feedback control board, the auxiliary heater having a liquid inlet connected to the main output of the third mixer and a liquid outlet connected to the pickling tank.

[0017] In a specific embodiment of the present invention, the system further includes an SPM storage tank. The main output port of the first mixer is connected to the main input port of the second mixer and the first liquid inlet of the SPM storage tank via three-way valves. The main output port of the second mixer is connected to the main input port of the third mixer and the second liquid inlet of the SPM storage tank via three-way valves. The main output port of the third mixer is connected to the liquid inlet of the auxiliary heater and the third liquid inlet of the SPM storage tank via three-way valves. The liquid outlet of the SPM storage tank and the liquid outlet of the auxiliary heater are connected to the pickling tank via three-way valves.

[0018] In a specific embodiment of the present invention, all four three-way valves are electrically connected to a feedback control board.

[0019] Furthermore, in a specific embodiment of the present invention, the first mixing device, the second mixing device, and the third mixing device are each provided with a pressure gauge and a safety valve communicating with the inside of the mixing pipe, and the pressure gauge and the safety valve are also electrically connected to the feedback control board.

[0020] In a specific embodiment of the present invention, the heater is composed of a heating tube wrapped around the mixing duct, and the first and second mixing devices are further provided with a heat insulating layer surrounding the heating tube, and the cooling channel of the third mixing device is disposed outside the heating tube, and the cooling channel is further surrounded by a heat insulating layer. [Effects of the Invention]

[0021] By adopting the above technical measures, the present invention achieves sufficient mixing of sulfuric acid and hydrogen peroxide through the split-stage mixing method, achieves precise temperature control, and ensures complete reaction of the mixed solution, so that the mixed solution supplied to the pickling bath meets the cleaning requirements and improves the quality and efficiency of wafer cleaning. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a schematic diagram of the system structure of the present invention. [Figure 2] 1 is a structural schematic diagram of a first mixing device. [Figure 3] 1 is a structural schematic diagram of the second mixing device. [Figure 4] 1 is a structural schematic diagram of the third mixing device. [Figure 5] 1 is a block diagram of electrical connections in the feedback control of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] As shown in FIG. 1, the liquid injection system of the wafer cleaning apparatus of the present invention includes an acid pickling tank 100, a first mixer 200, a second mixer 300, a third mixer 400, a cooling circulation device 500, an SPM storage tank 600, an auxiliary heater 700, and a feedback control board 90.

[0024] 2 to 4, the first mixing device 200, the second mixing device 300, and the third mixing device 400 each include a mixing duct 11, a plurality of mixing screws 12 installed in the mixing duct 11, a heater 13 wrapped around the outside of the mixing duct 11, and a heat insulating layer 14 installed around the heater 13. In this embodiment, the heater 13 is composed of a heating tube wrapped around the mixing duct 11.

[0025] 1 and 2, first mixer 200 has two main input ports 14a at its inlet end and one main output port 14b at its outlet end. The two input ports 14a of first mixer 200 are connected to sulfuric acid source 71 and hydrogen peroxide source 72 via main sulfuric acid line 101 and main hydrogen peroxide line 102, respectively. Main sulfuric acid line 101 and main hydrogen peroxide line 102 are each provided with a flow valve 85.

[0026] 1 and 3, second mixer 300 has one main input port 14a and two sub input ports 14c at its inlet end and one main output port 14b at its outlet end. The two sub input ports 14c of second mixer 300 are connected to sulfuric acid source 71 and hydrogen peroxide source 72 via adjusting sulfuric acid conduit 201 and adjusting hydrogen peroxide conduit 202, respectively. Main input port 14a of second mixer 300 is connected to output port 14b of first mixer 200 via a main conduit. Adjusting sulfuric acid conduit 201 and adjusting hydrogen peroxide conduit 202 are each provided with a flow valve 85.

[0027] 1 and 4, the third mixer 400 has a cooling circulation channel 24 between the heating pipe 13 and the insulating layer 14. The third mixer 400 has one main input port 14a at its inlet end and one main output port 14b at its outlet end. The cooling channel 24 has a cooling liquid inlet 24a and a cooling liquid outlet 24b, which are connected to the liquid outlet and liquid inlet of the cooling circulation device 500 via cooling ducts, respectively.

[0028] Furthermore, the main output port 14b of the first mixer 200 is connected via a first three-way valve 81 to the main input port 14a of the second mixer 300 and the first liquid inlet of the SPM storage tank 600, respectively.

[0029] The main output port 14b of the second mixer 300 is connected to the main input port 14a of the third mixer 400 and the second liquid inlet of the SPM storage tank 600 via a second three-way valve 82, respectively.

[0030] The main output port 14 b of the third mixer 400 is connected to the liquid inlet of the auxiliary heater 700 and the third liquid inlet of the SPM storage tank 600 via a third three-way valve 83 .

[0031] The liquid outlet of the SPM storage tank 600 and the liquid outlet of the auxiliary heater 700 are connected to the liquid inlet of the pickling tank 100 via a fourth three-way valve 84 .

[0032] The feedback control board 90 is electrically connected to the cooling circulation device 500 and controls the cooling circulation device 500 to supply circulating cooling liquid to the third mixer 400. This function makes it possible to cool the high-temperature mixed liquid entering the third mixer 400 and lower the temperature of the mixed liquid to an appropriate range.

[0033] 5, the feedback control board 90 is electrically connected to the heater 13 of the first mixing device 200, the heater 13 of the second mixing device 300, the heater 13 of the third mixing device 400, and the auxiliary heater 700. The feedback control board 90 receives temperature feedback from these three heaters 13 and the auxiliary heater 700 and can control their heating operations.

[0034] A thermometer 91 and an oxygen concentration meter 92 are respectively installed at the main output port of the first mixer 200, the main output port of the second mixer 300, the main output port of the third mixer 400, and the pickling tank 100. A pressure meter 93 and a safety valve 94 communicating with the inside of the mixing pipe 11 are also installed at the first mixer 200, the second mixer 300, and the third mixer 400, and these thermometer 91, oxygen concentration meter 92, pressure meter 93, and safety valve 94 are also electrically connected to the feedback control board 90.

[0035] Furthermore, the first, second, third and fourth three-way valves 81 , 82 , 83 , 84 and the four flow valves 85 are all electrically connected to the feedback control board 90 .

[0036] The liquid injection system of the wafer cleaning apparatus described above operates as follows. Sulfuric acid is supplied from the sulfuric acid supply source 71 and hydrogen peroxide is supplied from the hydrogen peroxide supply source 72 at a set ratio via the main sulfuric acid conduit 101 and main hydrogen peroxide conduit 102 to the mixing conduit 11 of the first mixer 200. As the sulfuric acid and hydrogen peroxide flow into the mixing conduit 11, they collide with the spiral surface of the mixing screw 12 and begin to rotate. The shear force generated by this rotation causes the sulfuric acid and hydrogen peroxide to penetrate each other. As a result of the collisions and rotations caused by the multiple mixing screws, the sulfuric acid and hydrogen peroxide are finally mixed completely and uniformly.

[0037] During the mixing process, the heater 13 of the first mixer 200 heats the mixed liquid in the tube. During this heating, the heater 13 transmits the heating temperature to the feedback control board 90, and the feedback control board 90 controls the heating temperature of the heater based on the received temperature.

[0038] A thermometer 91 and an oxygen concentration meter 92 installed at the main output port of the first mixer 200 monitor the temperature and oxygen concentration of the mixed liquid flowing out of the first mixer 200, respectively, and send the results to the feedback control board 90. If the temperature is below the required temperature, the feedback control board 90 continues to heat the incoming mixed liquid using the heater of the second mixer 300 while the mixed liquid is further mixed in the second mixer 300. If the oxygen concentration is below the required concentration, this indicates that the reaction is insufficient, and the feedback control board 90 opens the flow valves of the adjusting sulfuric acid pipe 201 and the adjusting hydrogen peroxide pipe 202 to increase the amount of sulfuric acid and hydrogen peroxide fed into the second mixer 300 at a set ratio, thereby allowing the reaction to proceed sufficiently.

[0039] A thermometer installed at the main output port of the second mixer 300 further monitors the temperature of the mixed liquid flowing out of the second mixer 300 and sends the data to the feedback control board 90. If the temperature exceeds the required temperature, the feedback control board 90 controls the cooling circulation device to cause circulating cooling liquid to flow into the cooling channel of the third mixer 400 to cool the mixed liquid. Conversely, if the temperature is below the required temperature, the feedback control board 90 controls the heater in the third mixer 400 to heat the mixed liquid.

[0040] A thermometer installed at the main output port of the third mixer 400 further monitors the temperature of the mixed liquid flowing out of the third mixer 400 and sends the data to the feedback control board 90. If the temperature is still below the required temperature, the auxiliary heater 700 is used to further heat the mixed liquid until the mixed liquid finally reaches the required temperature.

[0041] In addition, oxygen concentration meters 92 installed at the main output ports of second mixer 300 and third mixer 400 monitor the oxygen concentration of the outflowing mixed liquid and send the data to feedback control board 90. If the oxygen concentration at either point falls below the required concentration, feedback control board 90 opens the flow valves of adjustment sulfuric acid pipe 201 and adjustment hydrogen peroxide pipe 202, increasing the amount of sulfuric acid and hydrogen peroxide fed to second mixer 300 at a set ratio to allow the reaction to proceed sufficiently.

[0042] During the mixing process, pressure gauges monitor the pressure in the first mixer 200, the second mixer 300, and the third mixer 400, and transmit the data to the feedback control board 90. If the gas pressure in any mixer exceeds the set value, the feedback control board 90 controls and opens the safety valve installed in the corresponding mixer to reduce the pressure, thereby ensuring the safety of the system.

[0043] If the mixed liquid output from any of the mixing devices is sufficiently mixed and the temperature and oxygen concentration all meet the required values, the mixed liquid can be sent directly to the SPM storage tank 600 and stored at an incubator by switching the first three-way valve 81, second three-way valve 82, or third three-way valve 83 installed in the corresponding mixing device.

[0044] Furthermore, by switching the fourth three-way valve 84, it is possible to select whether the mixed liquid is supplied from the SPM storage tank 600 to the pickling tank 100 or whether the mixed liquid is supplied directly to the pickling tank through an adjustment pipe.

[0045] As can be seen from the above detailed description, the present invention employs a split-stage mixing method to achieve thorough mixing of sulfuric acid and hydrogen peroxide, thereby achieving accurate temperature control and ensuring complete reaction of the mixture, thereby ensuring that the mixture supplied to the pickling bath meets the cleaning requirements and improving the quality and efficiency of wafer cleaning.

Claims

1. A liquid injection system for a wafer cleaning apparatus including an acid pickling tank, a sulfuric acid supply source, and a hydrogen peroxide supply source, further comprising a first mixing device, a second mixing device, a feedback control board, a third mixing device, and a cooling circulation device; the first mixing device and the second mixing device each include a mixing conduit, a plurality of mixing screws provided within the mixing conduit, and a heater wrapped around the outside of the mixing conduit; the two main input ports of the first mixing device are connected to a sulfuric acid source and a hydrogen peroxide source via a main sulfuric acid line and a main hydrogen peroxide line, respectively; one main input port of the second mixer is connected to one main output port of the first mixer; the two sub-inlets of the second mixing device are connected to a sulfuric acid supply source and a hydrogen peroxide supply source via a regulated sulfuric acid line and a regulated hydrogen peroxide line, respectively; a main output port of the second mixer connected to the pickling tank; a thermometer and an oxygen concentration meter are respectively installed at the main output port of the first mixer and the main output port of the second mixer; a flow valve is installed in each of the main sulfuric acid pipe, the main hydrogen peroxide pipe, the adjusting sulfuric acid pipe, and the adjusting hydrogen peroxide pipe; the heater, the thermometer, the oximeter, and the flow valve are all electrically connected to the feedback control board; the third mixing device comprises a mixing conduit, a plurality of mixing screws disposed within the mixing conduit, and a heater and a cooling channel wound around the mixing conduit; a main input port of the third mixer is connected to a main output port of the second mixer, and a main output port of the third mixer is connected to the pickling tank; the cooling channel is provided with a cooling liquid inlet and a cooling liquid outlet, the cooling liquid inlet and the cooling liquid outlet being connected to the liquid outlet and the liquid inlet of the cooling circulation device, respectively, via a cooling pipe; The cooling circulation device is electrically connected to the feedback control board, and a thermometer and an oxygen concentration meter are also installed at the main output port of the third mixing device, which are electrically connected to the feedback control board.

1. A liquid injection system for a wafer cleaning apparatus.

2. further comprising an auxiliary heater electrically connected to the feedback control board; an inlet end of the auxiliary heater is connected to the main output port of the third mixing device, and an outlet end of the auxiliary heater is connected to the pickling tank; 2. The liquid injection system for a wafer cleaning apparatus according to claim 1.

3. Further comprising an SPM reservoir; a main output port of the first mixing device is connected to a main input port of the second mixing device and a first liquid inlet of the SPM storage tank via a three-way valve; a main output port of the second mixing device is connected to a main input port of the third mixing device and a second liquid inlet of the SPM storage tank via a three-way valve; the main output port of the third mixing device is connected to the inlet end of the auxiliary heater and the third liquid inlet of the SPM storage tank via a three-way valve; a liquid outlet of the SPM storage tank and an outlet end of the auxiliary heater are connected to the pickling tank via a three-way valve; 3. The liquid injection system for a wafer cleaning apparatus according to claim 2.

4. All four three-way valves are electrically connected to the feedback control board.

4. The liquid injection system for a wafer cleaning apparatus according to claim 3.

5. The first mixing device, the second mixing device, and the third mixing device are provided with a pressure gauge and a safety valve communicating with the inside of the mixing pipe, All of these pressure gauges and safety valves are electrically connected to the feedback control board.

4. The liquid injection system for a wafer cleaning apparatus according to claim 3.

6. the heater comprises a heating tube wrapped around the mixing conduit; The first mixing device and the second mixing device are provided with a heat insulating layer that wraps the heating pipe, The cooling channel of the third mixing device is provided outside the heating pipe, and a heat insulating layer is further wrapped around the outside of the cooling channel.

4. The liquid injection system for a wafer cleaning apparatus according to claim 3.

7. A thermometer and an oxygen concentration meter electrically connected to the feedback control board are also installed in the pickling tank.

4. The liquid injection system for a wafer cleaning apparatus according to claim 3.

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