Liquid Injection System of 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 belonging to the field of wafer process technology, and particularly to a liquid injection system of a wafer cleaning apparatus.

Background Art

[0002] In the cleaning process of semiconductor wafers, batch cleaning apparatuses are widely used as dedicated cleaning apparatuses using chemicals. So far, solutions suitable for different cleaning processes corresponding to the use of various wafer products have been developed.

[0003] General cleaning processes include, for example, film stripping, resist stripping, organic matter cleaning, removal of metal surface structures and metal residues, etc. For these, activated SPM (sulfuric acid hydrogen peroxide mixture) made by mixing sulfuric acid (H2SO4), hydrogen peroxide (H2O2), and ultrapure water is used. It is used as various active mixed solutions such as DSP+ added with SPM or ozone water by mixing at a specified concentration ratio. These solutions are used to clean contaminants adhering to the wafer substrate.

[0004] The active SPM mixed solution has a corrosive effect on semiconductor materials such as silicon (Si), silicon carbide (SiC), gallium nitride (GaN), gallium arsenide (GaAs), general metals, or organic substances with a relatively loose molecular structure, and functions for cleaning, etching, and removal. Therefore, it is frequently used in the cleaning process of semiconductor wafers.

[0005] In the SPM pickling process by a batch apparatus, corresponding piping paths for supplying sulfuric acid (H2SO4), hydrogen peroxide (H2O2), and ultrapure water are used. After being injected from each supply pipe, it finally passes through a transport pipe, a circulation pipe, a circulation pump, a filter, a mixer, a temporary storage tank, and a discharge pipe, and is sent to the corresponding pickling tank. Then, the preparation for cleaning is carried out.

[0006] However, in this transportation process, there are drawbacks such as uneven mixing, large errors in temperature control, and insufficient reaction. These problems bring fatal defects to the SPM pickling process of the tank-type device and cause a decrease in cleaning ability.

Summary of the Invention

Problems 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 device with uniform mixing, precise temperature control, and sufficient reaction, and to overcome the drawbacks existing in the prior art.

Means for Solving the Problems

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

[0009] The liquid injection system of the wafer cleaning device includes a pickling tank, a sulfuric acid supply source, and a hydrogen peroxide supply source, and 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 pipeline, a plurality of mixing screws provided in the mixing pipeline, and a heater covered outside the mixing pipeline.

[0011] The two main input ports of the first mixing device are respectively connected to the sulfuric acid supply source and the hydrogen peroxide supply source through the main sulfuric acid pipeline and the main hydrogen peroxide pipeline. The main input port of the second mixing device is connected to the main output port of the first mixing device. The two sub-input ports of the second mixing device are respectively connected to the sulfuric acid supply source and the hydrogen peroxide supply source through the adjustment sulfuric acid pipeline and the adjustment hydrogen peroxide pipeline. The main output port of the second mixing device is connected to the pickling tank.

[0012] A thermometer and an oxygen concentration meter are respectively provided at the main output ports of the first mixing device and the second mixing device, and flow valves are respectively installed in the main sulfuric acid pipeline, the main hydrogen peroxide pipeline, the sulfuric acid pipeline for adjustment, and the hydrogen peroxide pipeline for adjustment.

[0013] The heater, the thermometer, the oxygen concentration meter, and the flow valve are all electrically connected to the 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 pipeline, a plurality of mixing screws provided in the mixing pipeline, a heater and a cooling channel covered outside the mixing pipeline. The main input port of the third mixing device is connected to the main output port of the second mixing device, and the main output port of the third mixing device is connected to the pickling tank.

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

[0016] In a specific embodiment of the present invention, an auxiliary heater electrically connected to the feedback control board is further provided. The liquid inlet of the auxiliary heater is connected to the main output port of the third mixing device, and the liquid outlet is connected to the pickling tank.

[0017] In a specific embodiment of the present invention, an SPM storage tank is further provided. The main output port of the first mixing device is connected to the main input port of the second mixing device and the first liquid inlet of the SPM storage tank respectively through a three-way valve. The main output port of the second mixing device is connected to the main input port of the third mixing device and the second liquid inlet of the SPM storage tank respectively through a three-way valve. The main output port of the third mixing device is connected to the liquid inlet of the auxiliary heater and the third liquid inlet of the SPM storage tank respectively through a three-way valve. The liquid outlet of the SPM storage tank and the liquid outlet of the auxiliary heater are connected to the pickling tank through a three-way valve.

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

[0019] Furthermore, in a specific embodiment of the present invention, pressure gauges and safety valves communicating with the inside of the mixing pipeline are installed in the first mixing device, the second mixing device and the third mixing device. The pressure gauges and the safety valves are also electrically connected to the feedback control board.

[0020] Also, in a specific embodiment of the present invention, the heater is composed of a heating pipe wound around the mixing pipeline, and heat insulation layers wrapping the heating pipe are further provided in the first mixing device and the second mixing device. The cooling channel of the third mixing device is arranged outside the heating pipe, and a heat insulation layer is wrapped outside the cooling channel.

Advantages of the Invention

[0021] By adopting the above technical means, the present invention realizes sufficient mixing of sulfuric acid and hydrogen peroxide through a staged mixing method, 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.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

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

[0024] As shown in FIGS. 2 to 4, the first mixing device 200, the second mixing device 300, and the third mixing device 400 each include a mixing pipe 11, a plurality of mixing screws 12 installed in the mixing pipe 11, a heater 13 wound around the outside of the mixing pipe 11, and a heat insulation layer 14 installed outside the heater 13. The heater 13 in this embodiment is composed of a heating pipe wound around the mixing pipe 11.

[0025] As shown in the combination of FIGS. 1 and 2, the first mixing device 200 has two main input ports 14a at the inlet end and one main output port 14b at the outlet end. The two input ports 14a of the first mixing device 200 are respectively connected to a sulfuric acid supply source 71 and a hydrogen peroxide supply source 72 via a main sulfuric acid pipe 101 and a main hydrogen peroxide pipe 102. Flow valves 85 are respectively provided on the main sulfuric acid pipe 101 and the main hydrogen peroxide pipe 102.

[0026] As shown in combination with FIGS. 1 and 3, the second mixing device 300 has one main input port 14a and two sub-input ports 14c at the inlet end, and one main output port 14b at the outlet end. The two sub-input ports 14c of the second mixing device 300 are respectively connected to a sulfuric acid supply source 71 and a hydrogen peroxide supply source 72 via an adjustment sulfuric acid pipeline 201 and an adjustment hydrogen peroxide pipeline 202. The main input port 14a of the second mixing device 300 is connected to the output port 14b of the first mixing device 200 via a main pipeline. Flow valves 85 are respectively provided in the adjustment sulfuric acid pipeline 201 and the adjustment hydrogen peroxide pipeline 202.

[0027] As shown in combination with FIGS. 1 and 4, in the third mixing device 400, a cooling circulation channel 24 is provided between the heating pipe 13 and the heat insulation layer 14. The third mixing device 400 has one main input port 14a at the inlet end and one main output port 14b at the outlet end. The cooling channel 24 is provided with a coolant inlet 24a and a coolant outlet 24b, which are respectively connected to the liquid outlet and the liquid inlet of the cooling circulation device 500 via cooling pipelines.

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

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

[0030] The main output port 14b of the third mixing device 400 is respectively 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 that supplies the circulating cooling liquid to the third mixing device 400. With this function, it is possible to cool the high-temperature mixed liquid entering the third mixing device 400 and lower the temperature of the mixed liquid to an appropriate range.

[0033] As shown in combination with FIG. 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 respectively. The feedback control board 90 can receive the temperature feedback from these three heaters 13 and the auxiliary heater 700 and control their heating operations.

[0034] Also, a thermometer 91 and an oxygen concentration meter 92 are installed at the main output ports of the first mixing device 200, the second mixing device 300, the third mixing device 400, and the pickling tank 100 respectively. A pressure gauge 93 and a safety valve 94 communicating with the inside of the mixing pipe 11 are also installed in the first mixing device 200, the second mixing device 300, and the third mixing device 400. These thermometer 91, oxygen concentration meter 92, pressure gauge 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 above wafer cleaning device operates as follows. Sulfuric acid is supplied from the sulfuric acid source 71 and hydrogen peroxide is supplied from the hydrogen peroxide source 72 to the mixing pipe 11 of the first mixing device 200 at set ratios through the main sulfuric acid pipe 101 and the main hydrogen peroxide pipe 102 respectively. When the sulfuric acid and hydrogen peroxide flow into the mixing pipe 11, they collide with and rotate on the spiral surface of the mixing screw 12. Due to the shear force generated by this rotation, the sulfuric acid and hydrogen peroxide penetrate each other. Under the action of collision and rotation by a plurality of mixing screws, finally the sulfuric acid and hydrogen peroxide are completely and uniformly mixed.

[0037] During the mixing process, the heater 13 of the first mixing device 200 heats the mixed liquid in the pipe. 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] The thermometer 91 and the oxygen concentration meter 92 installed at the main output port of the first mixing device 200 monitor the temperature and oxygen concentration of the mixed liquid flowing out of the first mixing device 200 respectively, and transmit them to the feedback control board 90. When the temperature is below the required temperature, during the process of further mixing the mixed liquid in the second mixing device 300, the feedback control board 90 uses the heater of the second mixing device 300 to continuously heat the incoming mixed liquid. When the oxygen concentration is below the required concentration, it indicates that the reaction is insufficient. The feedback control board 90 opens the flow valves of the adjusting sulfuric acid pipe 201 and the adjusting hydrogen peroxide pipe 202, and increases the input amounts of sulfuric acid and hydrogen peroxide at the set ratios in the second mixing device 300 to allow the reaction to proceed sufficiently.

[0039] The thermometer installed at the main outlet of the second mixing device 300 further monitors the temperature of the mixed liquid flowing out of the second mixing device 300 and transmits the data to the feedback control board 90. When the temperature exceeds the required temperature, the feedback control board 90 controls the cooling circulation device to allow the circulating coolant to flow into the cooling channel of the third mixing device 400 to cool the mixed liquid. Conversely, when the temperature is below the required temperature, the feedback control board 90 controls the heater in the third mixing device 400 to heat the mixed liquid.

[0040] The thermometer installed at the main outlet of the third mixing device 400 further monitors the temperature of the mixed liquid flowing out of the third mixing device 400 and transmits the data to the feedback control board 90. When the temperature is still below the required temperature, the auxiliary heater 700 is used to further heat the mixed liquid so that the mixed liquid finally reaches the required temperature.

[0041] Also, the oxygen concentration meters 92 installed at the main outlets of the second mixing device 300 and the third mixing device 400 monitor the oxygen concentration of the mixed liquid flowing out respectively and transmit the data to the feedback control board 90. When the oxygen concentration is below the required concentration at any position, the feedback control board 90 opens the flow valves of the sulfuric acid pipeline 201 for adjustment and the hydrogen peroxide pipeline 202 for adjustment, and increases the input amounts of sulfuric acid and hydrogen peroxide to the second mixing device 300 at a set ratio to allow the reaction to proceed sufficiently.

[0042] During the mixing process, the pressure gauge monitors the pressure inside the first mixing device 200, the second mixing device 300, and the third mixing device 400 and transmits the data to the feedback control board 90. When the gas pressure in any of the mixing devices exceeds the set value, the feedback control board 90 controls the safety valve installed in the corresponding mixing device to open for pressure reduction. Thereby, the safety of the system is ensured.

[0043] When the mixed solution output by any mixing device is sufficiently mixed and all of the temperature and oxygen concentration meet the required values, by switching the first three-way valve 81, the second three-way valve 82, and the third three-way valve 83 installed in the corresponding mixing device, the mixed solution can be directly sent to the SPM storage tank 600 for heat preservation storage.

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

[0045] As is clear from the above detailed description, the present invention adopts a stepwise mixing method to achieve sufficient mixing of sulfuric acid and hydrogen peroxide. As a result, accurate control of the temperature is achieved and a complete reaction of the mixed solution is ensured. As a result, it is ensured that the mixed solution supplied to the pickling tank meets the cleaning requirements, and the quality and efficiency of wafer cleaning are improved.

Claims

1. A liquid injection system for a wafer cleaning apparatus including a pickling tank, a sulfuric acid supply source, and a hydrogen peroxide supply source, further comprising a first mixing device, a second mixing device, and a feedback control board, wherein each of the first mixing device and the second mixing device includes a mixing pipe, a plurality of mixing screws provided in the mixing pipe, and a heater wound around the outside of the mixing pipe, two main input ports of the first mixing device are respectively connected to the sulfuric acid supply source and the hydrogen peroxide supply source via a main sulfuric acid pipe and a main hydrogen peroxide pipe, one main input port of the second mixing device is connected to one main output port of the first mixing device, two sub-input ports of the second mixing device are respectively connected to the sulfuric acid supply source and the hydrogen peroxide supply source via an adjustment sulfuric acid pipe and an adjustment hydrogen peroxide pipe, the main output port of the second mixing device is connected to the pickling tank, a thermometer and an oxygen concentration meter are respectively installed at the main output port of the first mixing device and the main output port of the second mixing device, flow valves are respectively installed in the main sulfuric acid pipe, the main hydrogen peroxide pipe, the adjustment sulfuric acid pipe, and the adjustment hydrogen peroxide pipe, the heater, the thermometer, the oxygen concentration meter, and the flow valve are all electrically connected to the feedback control board, characterized in that it is a liquid injection system for a wafer cleaning apparatus.

2. further comprising a third mixing device and a cooling circulation device, wherein the third mixing device includes a mixing pipe, a plurality of mixing screws provided in the mixing pipe, a heater wound around the outside of the mixing pipe, and a cooling channel, the main input port of the third mixing device is connected to the main output port of the second mixing device, and the main output port of the third mixing device is connected to the pickling tank, a coolant inlet and a coolant outlet are provided in the cooling channel, and the coolant inlet and the coolant outlet are respectively connected to the liquid outlet and the liquid inlet of the cooling circulation device via cooling pipes, the cooling circulation device is electrically connected to the feedback control board, and a thermometer and an oxygen concentration meter electrically connected to the feedback control board are also installed at the main output port of the third mixing device, characterized in that it is the liquid injection system for a wafer cleaning apparatus according to Claim 1.

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

4. Further comprising an SPM storage tank, The main output port of the first mixing device is respectively connected to the main input port of the second mixing device and the first liquid inlet of the SPM storage tank through a three-way valve, The main output port of the second mixing device is respectively connected to the main input port of the third mixing device and the second liquid inlet of the SPM storage tank through a three-way valve, The main output port of the third mixing device is respectively connected to the inlet end of the auxiliary heater and the third liquid inlet of the SPM storage tank through a three-way valve, The liquid outlet of the SPM storage tank and the outlet end of the auxiliary heater are connected to the pickling tank through a three-way valve. The liquid injection system of the wafer cleaning device according to claim 3, characterized in that.

5. All four three-way valves are electrically connected to the feedback control board. The liquid injection system of the wafer cleaning device according to claim 4, characterized in that.

6. A pressure gauge and a safety valve communicating with the inside of the mixing pipeline are installed in the first mixing device, the second mixing device, and the third mixing device. All of these pressure gauges and safety valves are electrically connected to the feedback control board. The liquid injection system of the wafer cleaning device according to claim 4, characterized in that.

7. The heater is composed of a heating pipe wound around the mixing pipeline. The first mixing device and the second mixing device are provided with a heat insulation layer wrapping the heating pipe. The cooling channel of the third mixing device is provided outside the heating pipe, and a heat insulation layer is wrapped outside the cooling channel. The liquid injection system of the wafer cleaning device according to claim 4, characterized in that.

8. A thermometer and an oxygen concentration meter electrically connected to the feedback control board are also installed in the pickling tank. The liquid injection system of the wafer cleaning device according to claim 4, characterized in that.

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