In-line water scrubber system for semiconductor processing

Abstract

A semiconductor processing system includes a vacuum pump having an inlet and an outlet, wherein the inlet of the vacuum pump is configured to be in fluid communication with the outlet of a semiconductor reactor, and wherein the vacuum pump is configured to output exhaust gas from the reactor at the outlet of the vacuum pump. The semiconductor processing system also includes a water scrubber system at the outlet of the vacuum pump, having a vertical orientation relative to the pump and having an inlet and at least one mixing chamber. The inlet is in fluid communication with the outlet of the vacuum pump and the mixing chamber. The scrubber system is configured to maintain the temperature of the exhaust gas at the pump outlet as the exhaust gas is directed to the mixing chamber, and to inject water into the exhaust gas to remove water-based reaction products from the exhaust gas.

Description

Background Technology

[0001] Figure 1 A typical semiconductor processing system flowchart is shown. Semiconductor devices are produced by processing single-crystal silicon wafers through numerous steps using various chemical vapors under high vacuum. Using these chemical vapors in the manufacture of semiconductor devices is not very efficient; therefore, more than 50 percent or more of the chemical vapors exit the processing chamber through a vacuum fore-line connected to a vacuum pump. The exhaust gas from the vacuum pump, at one atmosphere, is heavily diluted with nitrogen to prevent the possibility of explosion in the presence of flammable chemical vapors. The pump exhaust line is typically heated to 100-200°C to prevent condensation of volatile chemical vapors. The nitrogen-diluted chemical vapors are then destroyed in a de-escalation system using high temperatures generated by the combustion of methane gas or an electric arc discharge.

[0002] Titanium tetrachloride is a liquid at room temperature with a boiling point of 136.6°C. It is highly reactive with water and is used in the chemical vapor deposition of titanium nitride films when reacting with ammonia. When titanium tetrachloride is used in semiconductor processing, the pump exhaust will consist of unreacted titanium tetrachloride, ammonia from nitrogen, and other chemical byproducts. The pump exhaust line can be 15 to 40 feet long or longer. Any cold spots in this line will cause condensation of titanium tetrachloride. This can lead to hazardous conditions because the accumulation of liquid chemicals can undergo subsequent reactions and cause localized corrosion in the pump exhaust line if any water condensation occurs during handling or routine maintenance.

[0003] Tungsten hexafluoride has a boiling point of 17°C. It reacts with water and is widely used in semiconductor processing. The use of nitrogen for dilution and the exhaust lines of the heating pump are critical for safe and continuous operation.

[0004] Ammonium nitrate, with a boiling point of 210°C and a melting point of 169.6°C, is a product of various chemical vapor-phase reactions that can occur in the processing chamber or along the upstream pipeline. If the pump's exhaust line is not heated to 250°C, ammonium nitrate will condense and deposit. The accumulation of this chemical in the pump exhaust line can create localized deposits that can spontaneously explode due to chemical reactions with the pump exhaust or due to friction / vibration in the exhaust line (e.g., during maintenance schedules).

[0005] Advanced semiconductor processing employs atomic layer deposition of alumina. A typical chemical vapor source used for this deposition is trimethylaluminum (TMA), which has a boiling point of 125–130 °C and reacts aggressively with water. In these processes, the pump exhaust line must be heated very uniformly to at least 200 °C. Any cold spot in the line can lead to TMA condensation, resulting in extremely dangerous and costly maintenance procedures. It has been widely reported that TMA condensation at the inlet of the emission reduction system leads to inlet pipe blockage and increased hazardous maintenance problems.

[0006] In addition, chlorine trifluoride (ClF3), used in some special treatments for room cleaning, can be found in the pump exhaust line. ClF3 is highly reactive with water and involves dangerous and expensive maintenance procedures. Attached Figure Description

[0007] Figure 1 This is a schematic diagram of a prior art semiconductor processing system with an emission reduction system in the exhaust line of a vacuum pump;

[0008] Figure 2 This is a schematic diagram of a semiconductor processing system with a rear-pump in-line water scrubber system.

[0009] Figure 2A This is a schematic diagram of a semiconductor reactor, a semiconductor processing system pump, and a vertically arranged inline water scrubber system with a downstream pump located at the pump outlet.

[0010] Figure 3 yes Figure 2A Detailed cross-sectional view of the water scrubber system; and

[0011] Figure 4 It has an enhanced mass transfer surface area. Figure 2A Detailed cross-sectional view of the water scrubber system. Detailed Implementation

[0012] refer to Figure 2 Reference numeral 10 generally indicates a semiconductor processing system. The semiconductor processing system 10 includes a semiconductor reactor 12, a vacuum pump 14, and a device installed at the vacuum pump outlet 14b. Figure 3 The inline water scrubber system 16 and the emission reduction system are located at the pump outlet, for example, within 12 or 6 inches of the horizontal portion of the pump outlet bend, and further, in a vertical orientation, at the pump outlet. As will be described more fully below, the inline water scrubber system 16 is configured to effectively remove at least one or more, and optionally most (if not all) of the water-reactive chemicals, such as titanium tetrachloride, tungsten hexafluoride, ammonium nitrate, trimethylaluminum, chlorine trifluoride, and other vapors that readily react with and / or are absorbed by water, from the pump exhaust (exhaust gas from reactor 12). Due to the high water solubility of acid gases and ammonia, the inline water scrubber system can also remove acid gases and ammonia.

[0013] like Figure 2A and 3 As best shown in the diagram, the inline water scrubber system 16 includes... Figure 2AThe vacuum pump output 14b is connected to the inlet 16A and the outlet 16b for discharging the reduced exhaust gas. The inline water scrubber system 16 includes a first mixing chamber 18 and a second mixing chamber 20. As described more fully below, the first mixing chamber 18 maintains the heat of the exhaust gas entering the inline water scrubber system and mixes heated nitrogen with the exhaust gas, while the second chamber 20 mixes the heated nitrogen and exhaust gas mixture with water to perform a water-reactive chemical vapor reaction with the exhaust gas.

[0014] like Figure 3 As best shown, the first mixing chamber 18 is formed by three concentric conduits 18a, 18b, and 18c, such as cylindrical tubes. Suitable materials for conduits 18a, 18b, and 18c include metals, such as stainless steel 304 or 316, or other alloys. Conduits 18a, 18b, and 18c may also be made of polymeric materials, such as polypropylene, polyethylene, Teflon, or other plastics, provided the operating temperature is below the polymer's yield point / melting point. Conduit 18a, vertically oriented relative to the outlet of pump 14, is in fluid communication with the pump outlet at one end and is concentrically positioned within conduit 18b, which forms the inlet of conduit 18a and the inlet 16a of the inline water scrubber system 16. Therefore, conduit 18b is also vertically oriented. For example, the diameter of conduit 18a can be approximately 2 to 4 inches, and typically approximately 2.5 inches. The diameter of conduit 18b is approximately one inch larger than that of conduit 18a, and typically in the range of 3 to 5 inches, and optionally approximately 3.5 inches. Both conduits 18a and 18b can be cylindrical with a constant diameter along their entire length.

[0015] To help maintain the temperature of the exhaust gas from the pump, conduit 18b is configured to heat conduit 18a. For example, heated nitrogen flows through the space between the two conduits 18a and 18b to heat conduit 18a and the exhaust gas flowing through it, and subsequently mixes with the exhaust gas flowing from conduit 18a to form a heated nitrogen dilution mixture. For example, conduit 18b may be in fluid communication with a nitrogen supply source 22 via conduit 24, which is heated by a nitrogen heater (e.g., a conventional nitrogen heater) located inline in conduit 24. For example, the nitrogen is heated to a temperature in the range between room temperature and 250°C, but typically in the range of 150 to 200°C, thereby heating conduit 18a to at least 150 to 200°C.

[0016] Conduit 24 is in fluid communication with the lower end of conduit 18a, which is adjacent to and optionally adjacent to the inlet of conduit 18a, as described, which forms the inlet 16a of the inline water scrubber system 16. In this way, the temperature of the exhaust gas from pump 14 remains substantially constant. To further help maintain the high temperature of conduit 18a and the exhaust gas therein, conduit 18a may be insulated by an insulating layer 28. Suitable insulation may be formed by a sheath of glass fiber or quartz wool or any readily available insulating material. This insulation may also extend over conduit 24 to help maintain the high temperature of the nitrogen gas. Heated nitrogen gas may be introduced into conduit 18b at a flow rate ranging from 5 to 30 standard liters per minute or higher. In this way and at this location, the injection of heated nitrogen gas ensures that the pump exhaust gas is maintained at its high exhaust temperature, preventing the condensation of entrained chemical vapors.

[0017] To mix the heated nitrogen with the exhaust gas, both conduits 18a and 18b have open upper ends and terminate at the same or approximately the same location (or at the same height when vertically oriented). For example, each conduit 18a, 18b may have a length or height ranging from approximately 24 to 48 inches or longer, depending on the specific vapor to be removed / reacted / absorbed. Thus, after the heated nitrogen flows through conduit 18b and heats conduit 18a (and the exhaust gas thereon), the nitrogen then mixes with the exhaust gas flowing from the open upper end of conduit 18a. After mixing, the mixture is directed to a larger mixing area formed by conduit 18c to allow the mixture to expand and slow down.

[0018] In the illustrated embodiment, conduit 18c surrounds and is spaced apart from conduit 18b. Conduit 18c is also concentrically mounted along its entire length and is formed by another cylindrical tube with a larger diameter, typically 1 to 4 inches or more larger than conduit 18b, for example, about 4 to 9 inches in diameter, and optionally 7.5 inches. Therefore, a larger mixing area can be formed between conduit 18c and conduit 18b. To guide the mixture into conduit 18c, mixing chamber 18 may include a deflector 30 to deflect the mixture of heated nitrogen and exhaust gas downwards (in the illustrated vertical orientation).

[0019] In the illustrated embodiment, the deflector 30 includes, for example, a conical surface formed of a conical plate, which is mounted to or formed at the closed upper end of the conduit 18c. For example, the conical surface is angled such that when heated nitrogen and exhaust gas (as they leave their respective conduits) mix, they impact the conical surface, causing the mixture to change its flow direction from vertically upward to downward at an angle between about 30 and 60 degrees, as described, thereby allowing the gas mixture to expand.

[0020] Refer again Figure 3Water is directed into chamber 18, and more specifically, into a larger mixing zone within conduit 18c, to react with the water from the pump exhaust gas in a chemical vapor reaction. Additionally, water fills the bottom of chambers 18 and 20. In the illustrated embodiment, water is injected into conduit 18c via a Venturi nozzle 32 (e.g., a spiral Venturi nozzle), which directs water from a water distribution manifold 34 mounted above chambers 18 and 20 and injects it into chamber 18. In the illustrated embodiment, the water distribution manifold 34 includes a housing 48, which, as described below, encloses the upper end of conduit 18c, except for the aforementioned Venturi nozzle.

[0021] The second chamber 20 can similarly be formed by another coaxial conduit 36, which is concentrically mounted below the water distribution manifold 34 around conduit 18c. Conduit 36 ​​is also concentrically mounted along its entire length and is formed by another cylindrical tube of a larger diameter, typically 1 to 4 inches or more larger than conduit 18c, for example, approximately 5 to 13 inches or approximately 11.5 inches in diameter. The space between conduit 36 ​​and conduit 18c forms the second mixing chamber 20. The second mixing chamber 20 is configured to mix water with any remaining water-reactive chemical vapors in the pump exhaust gas.

[0022] The in-line water scrubber system 16 also includes a water recirculation loop 38 to circulate water through the mixing chamber. In the illustrated embodiment, the water recirculation loop 38 includes a circulation pump 38a, such as a high-capacity magnetically coupled water pump capable of pumping, for example, 10 to 25 gallons per minute. The pump inlet is in fluid communication with the mixing chamber 20 at its lower end via a conduit 38b, and the pump outlet is in fluid communication with the water distribution manifold 34 via a conduit 38c. Thus, the pump 38a can draw water from the bottom of the chamber 20 and redirect it to the water distribution manifold 34, which in turn directs water into chambers 18 and 20 via the aforementioned Venturi nozzle and the following additional Venturi nozzle.

[0023] Additionally, pump 38a can use water level controller 40 to maintain the water level in mixing chamber 20 and mixing chamber 18 at a given level. In the illustrated embodiment, water level controller 40 includes a cover 42 and a drain pipe 44 having a side opening 44a. Figure 3 As shown in the figure, the water level is controlled by the height of the drain pipe opening inside the water level controller.

[0024] Refer again Figure 3 As described above, the water distribution manifold 34 includes a housing 48. The housing 48 includes two chambers 50 and 52, for example, an upper chamber and a lower chamber, wherein chamber 52 distributes water to mixing chambers 18 and 20. Fresh water is introduced into chamber 50 via inlet 50a, where it is slightly mixed with the scrubbed exhaust gas from chambers 18 and 20 before being discharged into the pump exhaust line upstream of the in-line water scrubber system.

[0025] Water circulation loop 38 is in fluid communication with chamber 52, which is in fluid communication with mixing chamber 18 via Venturi nozzle 32 (as described above), and with mixing chamber 20 via Venturi nozzle 56. Nozzle 56 may also include a helical Venturi nozzle mounted on the lower wall of housing 48, and similarly mounted on the open ends of conduits 18b, 18c, and 36 as nozzle 32. Nozzle 56 is located above the space between conduits 36 and 18c and sprays water at a greater angle than nozzle 32, for example, in the range of approximately 90 to 150 degrees and optionally approximately 120 degrees.

[0026] The housing 48 is installed at the upper ends of conduits 18b, 18c and 36 (e.g.) Figure 3 (As shown), thus sealing the upper end of the conduit and forming a corresponding chamber. Chamber 20 is in fluid communication with chamber 50 of the water distribution manifold 34 via outlet 58, which extends or passes through chamber 52 and discharges clean exhaust gas into chamber 50, which then discharges clean exhaust gas via outlet 16b, which may be formed by a flange pipe 60 for connection to the pump exhaust line. Fresh water is introduced into chamber 50 via inlet 50a, which mixes slightly with the scrubbed exhaust gas from chamber 20, and is discharged into the pump exhaust line upstream of the in-line water scrubber system.

[0027] Pump 38a of the water recirculation loop 38 recirculates water at high flow rate and pressure into chamber 52 of the water distribution manifold 34. Recirculated water entering chamber 18 can be injected from chamber 52 through several pipes 32a, the number of which is between four and eight, typically six, depending on the specific scrubber system design, with Venturi nozzles 32 mounted at the ends of the respective pipes. The Venturi nozzles 32 can spray water into chamber 18 at an angle between approximately 30 and 60 degrees, typically approximately 50 degrees. This high-velocity, rotating water flow mixes rapidly with deflected hot nitrogen and exhaust gases at a narrow angle. It is in the first mixing chamber 18 of this inline water scrubber system that the water reacts with the pump exhaust water through a chemical vapor reaction.

[0028] The nitrogen and exhaust gases, no longer containing reactive water chemicals, are then turned upwards as shown, passing through the second mixing chamber 20 of the scrubber at even lower flow rates. These gases are further scrubbed by recirculated water flowing through a venturi nozzle 56, which, as described above, sprays water at a large angle ranging from 90 to 150 degrees, typically 120 degrees. The remaining nitrogen and permanent gases from the pump exhaust are then conveyed through four to six pipes forming outlet 58, as shown, to chamber 50 of the water distribution manifold 34.

[0029] Fresh water can be continuously added via inlet 50a of chamber 50 at the rate at which water is removed as wastewater.

[0030] The exhaust gas from an inline scrubber system primarily consists of nitrogen and permanent gases, depending on the specific semiconductor process. These permanent gases include carbon dioxide, oxygen, ozone, hydrogen, PFCs, and other gases. The scrubber system exhaust gas is then conveyed at one atmosphere through a pump exhaust line to an emission reduction system, where it is ultimately destroyed before being released into the atmosphere.

[0031] Reference Figure 4 The in-line water scrubber system 16 may also include multiple rings 80, such as Raschig rings, stacked in mixing chamber 20 or mixing chamber 18 or both chambers 20 to increase the mass transfer surface area. The rings may be formed from a variety of different materials compatible with the chemical vapors in the pump exhaust to increase the mass transfer surface area as described and to increase the absorption of acidic gases and ammonia.

[0032] This novel in-line water scrubber is ideally installed directly at the pump outlet (e.g., within 12 inches or 6 inches of the horizontal section of the pump outlet bend), allowing most (if not all) of these water-reactive chemicals to be removed by water, and water-reactive byproducts (such as solid oxides and acid and alkali solutions) to be discharged to the wastewater outlet before entering the pump exhaust line. Therefore, this in-line water scrubber assembly offers significant safety and cost advantages for continuous treatment operations with reduced maintenance intervals.

Claims

1. A semiconductor processing system, comprising: A vacuum pump having an inlet and an outlet, the inlet of the vacuum pump being configured to be in fluid communication with the outlet of a semiconductor reactor, and the vacuum pump being configured to output exhaust gas from the reactor at the outlet of the vacuum pump. as well as A water scrubber system at the outlet of the vacuum pump, the water scrubber system having a vertical orientation relative to the vacuum pump, the water scrubber system comprising: Mixing chamber (18); First catheter (18a); A second catheter (18b) is concentrically surrounding and spaced apart from the first catheter (18a); A third conduit (18c) is concentrically surrounding and spaced apart from the second conduit (18b); The inlet is in fluid communication with the outlet of the vacuum pump and the mixing chamber, and the inlet of the water scrubber system is in fluid communication with the first conduit (18a) to guide exhaust gas into the first conduit (18a), and the first conduit (18a) guides the exhaust gas into the mixing chamber (18). A heated nitrogen supply source for supplying heated nitrogen, the heated nitrogen supply source being in fluid communication with the second conduit (18b), the heated nitrogen supply source being configured to allow the heated nitrogen to flow between the second conduit (18b) and the first conduit (18a), thereby heating the first conduit (18a) and the exhaust gas flowing through the first conduit (18a) to maintain the temperature of the exhaust gas at the outlet of the vacuum pump and while the exhaust gas is directed to the mixing chamber (18), the first conduit (18a) and the second conduit (18b) being configured to mix the heated nitrogen with the exhaust gas to form a heated nitrogen dilution mixture after flowing through the first conduit (18a) and the second conduit (18b), and to redirect the heated nitrogen dilution mixture back into the mixing chamber (18); and A water supply source configured to inject water into the heated nitrogen dilution mixture to remove water reaction products from the exhaust gas.

2. The semiconductor processing system according to claim 1, wherein, The water scrubber system includes a water recirculation loop to recirculate water through the mixing chamber.

3. The semiconductor processing system according to claim 2, wherein, The water recirculation loop is configured to maintain the water level in the mixing chamber.

4. The semiconductor processing system according to claim 1, wherein, The water scrubber system includes multiple Raschig rings.

5. The semiconductor processing system according to claim 1, wherein, The water scrubber system is configured to redirect the mixture into a larger portion of the mixing chamber to allow the mixture to expand, and to inject water as the mixture flows into the larger portion.

6. The semiconductor processing system according to any one of claims 1 to 5, wherein, The mixing chamber is a first mixing chamber, the water washing system includes a second mixing chamber, and the first mixing chamber guides the mixture to the second mixing chamber.

7. The semiconductor processing system according to claim 6, wherein, The water washing system is configured to inject water into a mixture in the first mixing chamber and the second mixing chamber.

8. The semiconductor processing system according to claim 6, wherein, The water scrubber system is configured to inject water into the exhaust gas in the first mixing chamber using a first set of Venturi nozzles.

9. The semiconductor processing system according to claim 8, wherein, The water scrubber system is configured to inject water into the exhaust gas in the second mixing chamber using a second set of Venturi nozzles, wherein the first set of Venturi nozzles sprays water at a smaller angle than the second set of Venturi nozzles.

10. The semiconductor processing system according to claim 9, wherein, The first set of Venturi nozzles sprays water into the first mixing chamber at an angle between 30 and 60 degrees, and the second set of Venturi nozzles sprays water into the second mixing chamber at an angle between 90 and 150 degrees.

11. A linear water scrubber system, comprising: Mixing chamber (18); First catheter (18a); A second catheter (18b) is concentrically surrounding and spaced apart from the first catheter (18a); A third conduit (18c) is concentrically surrounding and spaced apart from the second conduit (18b); An inlet is provided for fluid communication with the outlet of a vacuum pump of a semiconductor processing system to receive exhaust gas from the outlet of the vacuum pump, and the inlet is also fluidly communication with the mixing chamber. The inlet of the water scrubber system is also fluidly communication with the first conduit (18a) to guide exhaust gas into the first conduit (18a), and the first conduit (18a) guides the exhaust gas into the mixing chamber (18). A heated nitrogen supply source is provided for supplying heated nitrogen gas, the heated nitrogen supply source being in fluid communication with the second conduit (18b), the heated nitrogen supply source being configured to allow the heated nitrogen gas to flow between the second conduit (18b) and the first conduit (18a) to thereby heat the first conduit (18a) and the exhaust gas flowing through the first conduit (18a) to maintain the temperature of the exhaust gas at the outlet of the vacuum pump and while the exhaust gas is directed to the mixing chamber (18), the first conduit (18a) and the second conduit (18b) being configured to mix the heated nitrogen gas with the exhaust gas to form a heated nitrogen dilution mixture after flowing through the first conduit (18a) and the second conduit (18b), and to redirect the heated nitrogen dilution mixture back into the mixing chamber (18); as well as A water supply source configured to inject water into the heated nitrogen dilution mixture to remove water reaction products from the exhaust gas.

12. The in-line water scrubber system according to claim 11, wherein, The water scrubber system is configured to redirect the mixture into a larger portion of the mixing chamber to allow the mixture to expand and to inject water as the mixture flows into the larger portion.

13. The in-line water scrubber system according to claim 12, wherein, The mixing chamber is a first mixing chamber, and also includes a second mixing chamber, wherein the first mixing chamber guides the mixture to the second mixing chamber.

14. The in-line water scrubber system according to claim 13, wherein, The water supply source is configured to inject water into the mixture in the first mixing chamber and the second mixing chamber.

15. The in-line water scrubber system according to claim 14, wherein, The water scrubber system is configured to spray water into the exhaust gas in the first mixing chamber using a first set of Venturi nozzles, and to spray water into the second mixing chamber using a second set of Venturi nozzles, wherein the first set of Venturi nozzles sprays water into the first mixing chamber at a smaller angle than the second set of Venturi nozzles.

16. A method for scrubbing semiconductor processing exhaust gas from a semiconductor processing system using an in-line water scrubber system according to claim 11, the semiconductor processing system having a reactor and a vacuum pump for pumping exhaust gas from the reactor, the vacuum pump having an inlet and an outlet, the method comprising: Provides a mixing room with an entrance; The mixing chamber is oriented vertically relative to the vacuum pump; A fluid communication is provided between the outlet of the vacuum pump and the inlet of the mixing chamber, and the scrubber system is configured to maintain the temperature of the exhaust gas at the outlet of the vacuum pump and as the exhaust gas is directed into the mixing chamber, and to direct water into the exhaust gas, thereby removing water reaction products and / or water-absorbing products from the exhaust gas.

17. The method according to claim 16, wherein, The vacuum pump outlet has a bend with a horizontal section, and the method further includes positioning the inlet of the mixing chamber within 12 inches of the horizontal section of the bend.

18. The method according to claim 17, wherein, The mixing chamber is a first mixing chamber, and also includes a second chamber, into which a mixture of water and heated nitrogen is diluted.

19. The method of claim 18, further comprising: Water is directed into the second chamber, thereby removing additional water reaction products and / or water-absorbing products from the exhaust gas.

20. The method of claim 17, wherein, Water guiding includes: spraying water using a Venturi nozzle.

21. The method according to any one of claims 17 to 20, wherein, The removal of water-reactive products includes the removal of water-reactive products selected from the group consisting of titanium tetrachloride, tungsten hexafluoride, ammonium nitrate, trimethylaluminum, and chlorine trifluoride.

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