Apparatus and method for recovery of nf3 charging off-gas
By combining a balance tank and a cold trap, the pressure range is controlled, enabling efficient recovery of NF3 filling tail gas and cylinder tail gas. This solves the problems of low recovery efficiency and pressure fluctuation in existing technologies, simplifies operation, and reduces costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- PERIC SPECIAL GASES CO LTD
- Filing Date
- 2024-01-03
- Publication Date
- 2026-06-16
AI Technical Summary
In the existing technology, the NF3 filling exhaust gas volume is small and the pressure is low, lacking an efficient recovery device, and may affect the pressure fluctuation after the analyzer, resulting in inaccurate analysis results. The existing device has a complex structure and is cumbersome to operate.
The device, which combines a balance tank and a cold trap, achieves efficient recovery of filling tail gas and cylinder tail gas by controlling the pressure range between -0.1 and 0 MPa and between -0.08 and 0.08 MPa. Liquid nitrogen condensation and reflux pipelines are used to maintain stable system pressure and avoid affecting the pressure of analytical instruments.
It achieves efficient recovery of filling exhaust gas and cylinder exhaust gas, ensures stable pressure after the analyzer, simplifies operation, improves recovery efficiency, and reduces costs.
Smart Images
Figure CN118149265B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of electronic special gas filling tail gas recovery technology, and in particular to a method and apparatus for NF3 filling tail gas recovery. Background Technology
[0002] With the development of the semiconductor industry, the use of high-purity electronic specialty gas NF3 has increased dramatically. Nitrogen trifluoride (NF3) is an excellent plasma etching gas in the microelectronics industry. For etching silicon and silicon nitride, NF3 exhibits higher etching rates and selectivity than carbon tetrafluoride (CTF) and mixtures of CTF and oxygen, and it leaves no surface contamination. Especially in the etching of integrated circuit materials with a thickness of less than 1.5 μm, NF3 demonstrates excellent etching rates and selectivity, leaving no residue on the etched surface. It is also an excellent cleaning agent. With the development of nanotechnology and the large-scale development of the electronics industry, its demand will continue to increase. Because frequent analysis and testing are required during the filling of high-purity NF3, and some residual gas remains in the cylinders after use, directly evacuating and disposing of this exhaust gas would result in significant waste. Therefore, the recovery of filling exhaust gas and cylinder exhaust gas generated during the filling of high-purity NF3 is particularly important for improving production and reducing energy consumption. Currently, due to the small volume and low pressure of the filling exhaust gas, there is no good method for efficient recovery. In addition, the recovery of filling exhaust gas may affect the pressure fluctuations after the analyzer, thus affecting the analysis results. Therefore, it is particularly difficult to adopt a single device to recover both filling exhaust gas and cylinder exhaust gas.
[0003] The announcement of Chinese patent CN218327503U discloses a device for recovering residual gas from gas cylinders. This utility model uses a vacuum pump to draw residual gas from the gas cylinder through the suction pipe. After mixing with distilled water, the gas enters the vaporizer for vaporization. Then, a vacuum pump draws the gas from the transmission pipe into the compressor for compression. Finally, the gas enters the gas cylinder again through the delivery pipe to complete the recovery and reuse. Although it improves the utilization rate of resources to a certain extent, the device has a complex structure, is cumbersome to operate, and is not easy to use.
[0004] Chinese patent CN203082543U discloses a device for recovering krypton and xenon from steel cylinders. This utility model patent uses a vacuum pump to extract the remaining krypton and xenon gas from the steel cylinder and then uses low-temperature freezing technology to condense and reuse the krypton and xenon gas. However, this patent requires a vacuum pump to extract the gas, which will inevitably cause another kind of resource loss, and at the same time, it cannot guarantee the efficient recovery of krypton and xenon gas.
[0005] In summary, due to the small residual gas volume and low pressure of NF3 cylinders, there is currently no device specifically designed for the recovery of NF3 filling exhaust gas. Furthermore, the cylinder residual gas recovery devices in the prior art are complex and cumbersome to operate. In addition, the recovery of filling exhaust gas may affect the pressure fluctuations after the analyzer, thus affecting the analysis results. Therefore, this application proposes a device and method for the recovery of NF3 filling exhaust gas. Summary of the Invention
[0006] In order to address the problems existing in the background technology and optimize the existing high-purity electronic special gas tail gas recovery technology, this application provides an apparatus and method for NF3 filling tail gas recovery. It not only achieves efficient recovery of filling tail gas and cylinder tail gas in one set of equipment, but also ensures the stability of the pressure after the analyzer, avoiding the influence of the analysis results. The equipment is simple, low-cost, easy to operate, and has high tail gas recovery efficiency, providing a method and idea for production units to increase production and reduce consumption.
[0007] The technical solution of this application is as follows:
[0008] On the one hand, this application proposes an apparatus for recovering NF3 filling exhaust gas, comprising:
[0009] The system includes a balance tank and a cold trap. The balance tank's inlet is connected to the filling exhaust gas, and an outlet regulating valve is installed on the balance tank's outlet pipe. The cold trap's inlet is connected to the residual gas from the filling cylinder, the weighing residual gas, and the balance tank's outlet. The cold trap's outlet is connected to the vaporizer's inlet. The vaporizer is equipped with a return pipe, and the vaporizer's outlet is connected to the NF3 storage tank.
[0010] Preferably, the cold trap is equipped with a pressure gauge, the bottom of the cold trap is connected to the tail nitrogen outlet pipeline, the top of the cold trap is connected to the liquid nitrogen inlet regulating valve, and the nitrogen inlet regulating valve is connected to the liquid nitrogen inlet pipeline.
[0011] Preferably, one end of the return pipeline is connected to the gas outlet of the vaporizer, and the other end is connected to the cold trap. The return pipeline is connected to the cold trap for gas return, and a cold trap gas return regulating valve is provided on the return pipeline.
[0012] On the other hand, this application proposes a method for recovering exhaust gas during NF3 filling, as detailed below.
[0013] S1.NF3 filling exhaust gas enters the balance tank. The balance tank pressure is interlocked with the outlet regulating valve diaphragm valve to control the balance tank pressure to -0.08 to 0.08 MPa. When the pressure is higher than 0.08 MPa, the outlet regulating valve opens; when the pressure is lower than -0.08 MPa, the outlet regulating valve closes.
[0014] S2. Then one or more of the tail gas, cylinder residual gas and weighing residual gas that enter the balance tank enter the cold trap, and then the liquid phase NF3 enters the vaporizer.
[0015] S3. After vaporization, the gaseous NF3 enters the NF3 storage tank for later use, while the gaseous NF3 also flows back to the cold trap to maintain the pressure difference of the liquid NF3 flowing into the vaporizer in the cold trap.
[0016] 6. Preferably, the pressure of the NF3 filling exhaust gas before entering the balance tank in S1 is -0.1 to 0 MPa; the pressure of the cold trap in S2 is -0.1 to 0 MPa; and the formula for calculating the pressure difference in S3 is as follows.
[0017] P0 = P B -P C +P D
[0018] Where P0 is the pressure difference, P B P is the pressure of the cold trap. C For the pressure of the carburetor, P D The pressure difference caused by the height difference between the cold trap and the vaporizer.
[0019] The beneficial effects of this application are:
[0020] (1) This application provides a method and apparatus for recovering NF3 filling tail gas, which not only efficiently realizes the recovery of filling tail gas and cylinder tail gas in one set of equipment, but also ensures the stability of the pressure after the analyzer, avoiding the influence of the analysis results. The equipment and method are simple and highly efficient, providing a method and idea for production units to increase production and reduce consumption.
[0021] (2) Before the filling exhaust gas enters the balance tank, this application sets the pressure to within the range of -0.1 to 0 MPa to form a slightly negative pressure environment, so as to ensure that the filling exhaust gas can effectively enter the balance tank under negative pressure.
[0022] (3) In this application, the pressure of the balance tank is set at -0.08 to 0.08 MPa, and the pressure of the balance tank is interlocked with the diaphragm valve at the outlet of the balance tank, so as to effectively stabilize the pressure of the balance tank, while avoiding excessive or insufficient pressure, which would affect the opening and closing of the valve and thus affect the recovery effect.
[0023] (4) This application keeps the cold trap under negative pressure to ensure that the liquid NF3 can flow smoothly into the vaporizer. At the same time, a reflux device is set between the vaporizer and the cold trap to form a negative pressure difference using the gaseous NF3. The entire system is designed to internally adjust the pressure to avoid affecting the purity of the recovered gas by introducing other gases. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of the device for recovering exhaust gas during NF3 filling, as described in this application.
[0025] Explanation of reference numerals in the attached diagram: A, Balance tank; B, Cold trap; C, Vaporizer; D, NF3 storage tank; 1, Outlet regulating valve; 2, Liquid nitrogen inlet regulating valve; 3, Cold trap return gas regulating valve; S1, Filling tail gas; S2, Cylinder residual gas; S3, Weighing residual gas; S4, Cold trap return gas; S5, NF3 storage tank outlet pipeline; S6, Liquid nitrogen inlet pipeline; S7, Tail nitrogen outlet pipeline. Detailed Implementation
[0026] To further illustrate the technical means and effects adopted in this application to achieve the intended purpose of the invention, the following is in conjunction with the appendix. Figure 1 The following is a detailed description of the specific implementation methods, structures, features, and effects according to the present application, as well as preferred embodiments.
[0027] Example 1
[0028] This embodiment provides a device for recovering exhaust gas during NF3 filling, as detailed below:
[0029] A device for recovering NF3 filling tail gas includes a balance tank A and a cold trap B. The inlet of balance tank A is connected to the filling tail gas S1, and an outlet regulating valve 1 is installed on the outlet pipe of balance tank A. The inlet of cold trap B is connected to the residual gas S2 from the filling cylinder, the residual weighing gas S3, and the outlet of balance tank A. The outlet of cold trap B is connected to the inlet of vaporizer C. A return pipe is installed on vaporizer C, and the outlet of vaporizer C is connected to an NF3 storage tank D. A pressure gauge is also installed on cold trap B. The bottom of cold trap B is connected to the tail nitrogen outlet pipe S7, and the top of cold trap B is connected to a liquid nitrogen inlet regulating valve 2, which is connected to a liquid nitrogen inlet pipe S6. One end of the return pipe is connected to the outlet of vaporizer C, and the other end is connected to cold trap B. The return pipe is connected to cold trap return gas S4, and a cold trap B return gas regulating valve 3 is installed on the return pipe.
[0030] Example 2
[0031] Based on the apparatus of Embodiment 1, this embodiment provides a method for recovering NF3 filling exhaust gas, as detailed below.
[0032] S1.NF3 filling tail gas S1 enters balance tank A through a gas pipeline. The pressure of NF3 filling tail gas S1 before entering balance tank A is controlled between -0.1 and 0 MPa. The function of balance tank A is to stabilize the pipeline pressure after the analyzer and ensure the accuracy of the analysis results while collecting NF3 filling tail gas S1. The pressure of balance tank A is interlocked with the outlet regulating valve to form a diaphragm valve. The pressure of balance tank A is in the range of -0.08 to 0.08 MPa. When the pressure of balance tank A is higher than 0.08 MPa, the outlet regulating valve 1 opens; when the pressure of balance tank A is lower than -0.08 MPa, the outlet regulating valve 1 closes.
[0033] S2. Subsequently, one or more of the following: the NF3 filling tail gas S1, the residual gas from the cylinder S2, and the weighing residual gas S3 from the balance tank A enter the cold trap B through a connected pipe. The cold trap B maintains a negative pressure, with the pressure range controlled between -0.1 and 0 MPa. Under the action of liquid nitrogen, the gas condenses. Liquid nitrogen enters the cold trap B from the liquid nitrogen inlet pipe S6 through the liquid nitrogen inlet regulating valve 2, condensing the gas entering the cold trap B. After condensation, the gaseous nitrogen is discharged from the tail nitrogen outlet pipe S7, and the liquid phase NF3 enters the vaporizer C for vaporization under the action of the pressure difference.
[0034] S3. After heating and vaporization, a portion of the gaseous NF3 flows back to the cold trap B through the cold trap B return gas to maintain the pressure difference between the liquid NF3 in the cold trap B and the vaporizer C. The pressure difference here refers to the pressure increase as the NF3 in the vaporizer C vaporizes, the obstruction of the liquid NF3 in the cold trap B entering the vaporizer, and the return flow through the vaporizer C to maintain the pressure difference. The pressure difference is specifically the cold trap pressure - vaporizer pressure + the pressure difference caused by the height difference between the two devices. The other portion of the gaseous NF3 enters the NF3 storage tank D through the pipeline for standby. When in use, it is taken out from the gas outlet pipeline of the NF3 storage tank.
[0035] Examples 3-5
[0036] Based on the NF3 filling exhaust gas recovery method provided in Example 2, the main difference between Examples 3-5 is that the pressures of the balance tank and the cold trap are different, as shown in Table 1.
[0037] Table 1
[0038]
[0039] Comparative Example 1
[0040] The main difference between this comparative example and Example 4 is that the NF3 filling exhaust gas pressure is 0-0.2 MPa.
[0041] Comparative Example 2
[0042] The main difference between this comparative example and Example 4 is that the NF3 filling exhaust gas pressure is -0.3 to -0.2 MPa.
[0043] Comparative Example 3
[0044] The main difference between this comparative example and Example 4 is that the pressure of the balance tank is 0.1 to 0.2 MPa.
[0045] Comparative Example 4
[0046] The main difference between this comparative example and Example 4 is that the pressure of the balance tank is -0.2 to -0.1 MPa.
[0047] Comparative Example 5
[0048] The main difference between this comparative example and Example 4 is that the cold trap pressure is 0.1 to 0.2 MPa.
[0049] Comparative Example 6
[0050] The main difference between this comparative example and Example 4 is that the cold trap pressure is -0.3 to -0.2 MPa.
[0051] Performance testing
[0052] Based on the principles of high-temperature pyrolysis and electrochemistry, the NF3 content in the gas recovered from the filling tail gas cylinder was detected, and the results are shown in Table 2.
[0053] Table 2
[0054]
[0055]
[0056] Results Analysis
[0057] As can be seen from the comparison of Examples 1-5 and Comparative Examples 1-6, the apparatus and method of this application can effectively recover filling exhaust gas. However, through comparison, it was found that the recovery effect of Examples 3-5 is far superior to that of Comparative Examples 1-6. This may be because within the pressure range of each apparatus defined in this application, almost all of the filling exhaust gas can enter the cold trap. At the same time, under the condensation of liquid nitrogen, it becomes liquid NF3, which then enters the vaporizer for vaporization. After vaporization, part of the gaseous NF3 flows back to the cold trap through the cold trap return gas to maintain the pressure difference of the liquid NF3 flowing into the vaporizer (C) in the cold trap, and the other part of the gaseous NF3 enters the NF3 storage tank through the pipeline for later use. In contrast, the pressure of each apparatus in Comparative Examples 1-7 is within the range defined in this application. It is possible that due to excessive or insufficient pressure, the airflow of the entire apparatus is unstable, and it is impossible to completely draw the filling exhaust gas out of the bottle under negative pressure, so the filling exhaust gas cannot be recovered efficiently.
[0058] The above description is merely a preferred embodiment of this application and is not intended to limit this application in any way. Although this application has been disclosed above with reference to preferred embodiments, it is not intended to limit this application. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the technical solution of this application. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.
Claims
1. A device for recovering exhaust gas from NF3 filling, characterized in that, include: The balance tank (A) and the cold trap (B) are connected. The air inlet of the balance tank (A) is connected to the filling exhaust gas (S1). An outlet regulating valve (1) is installed on the outlet pipe of the balance tank (A). The air inlet of the cold trap (B) is connected to the residual gas (S2) and the weighing residual gas (S3) of the filling cylinder and the air outlet of the balance tank (A). The air outlet of the cold trap (B) is connected to the air inlet of the vaporizer (C). A return pipe is installed on the vaporizer (C). The air outlet of the vaporizer (C) is connected to the NF3 storage tank (D).
2. The device for recovering NF3 filling exhaust gas according to claim 1, characterized in that, A pressure gauge is installed on the cold trap (B). The bottom of the cold trap (B) is connected to the tail nitrogen outlet pipeline (S7). The top of the cold trap (B) is connected to the liquid nitrogen inlet regulating valve (2). The liquid nitrogen inlet regulating valve (2) is connected to the liquid nitrogen inlet pipeline (S6).
3. The device for recovering NF3 filling exhaust gas according to claim 1, characterized in that, One end of the return pipeline is connected to the outlet of the vaporizer (C), and the other end is connected to the cold trap (B). The return pipeline is connected to the cold trap return gas (S4), and a cold trap return gas regulating valve (3) is provided on the return pipeline.
4. A method for recovering exhaust gas from NF3 filling, characterized in that, Specifically as follows: Step 1. The NF3 filling exhaust gas (S1) enters the balance tank (A). The pressure of the balance tank (A) and the outlet regulating valve (1) form a diaphragm valve interlock to control the pressure of the balance tank (A) to -0.08~0.08MPa. When the pressure is higher than 0.08MPa, the outlet regulating valve (1) opens, and when the pressure is lower than -0.08MPa, the outlet regulating valve (1) closes. Step 2. One or more of the NF3 filling tail gas (S1), cylinder residual gas (S2) and weighing residual gas (S3) entering the balance tank (A) enter the cold trap (B), and then the liquid phase of NF3 enters the vaporizer (C). Step 3. After vaporization, the gaseous NF3 enters the NF3 storage tank (D) for standby, while the gaseous NF3 also flows back to the cold trap (B) to maintain the pressure difference of the liquid NF3 flowing into the vaporizer (C) in the cold trap (B).
5. The method for recovering NF3 filling exhaust gas according to claim 4, characterized in that, The pressure of the NF3 filling exhaust gas (S1) before entering the balance tank (A) in step 1 is -0.1~0 MPa; the pressure of the cold trap (B) in step 2 is -0.1~0 MPa; the formula for calculating the pressure difference in step 3 is as follows. P0=P B -P C +P D Where P0 is the pressure difference, P B For the pressure of the cold trap (B), P C For the pressure of the vaporizer (C), P D The pressure difference caused by the height difference between the cold trap (B) and the vaporizer (C).