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CN-121973988-A - Quantitative conveying system and quantitative conveying method for liquid

CN121973988ACN 121973988 ACN121973988 ACN 121973988ACN-121973988-A

Abstract

The application provides a quantitative conveying system and a quantitative conveying method for liquid. The quantitative conveying system comprises a buffer tank, a liquid supply valve, a gas control system, a flow limiting element and a switching valve. When the liquid is quantitatively conveyed, the liquid supply valve is closed to isolate the buffer tank, and a preset stable positive pressure is applied to the tank by the gas control system. The constant positive pressure, in combination with the fixed flow resistance of the restriction element on the delivery line, determines a constant liquid flow rate. The controller calculates the duration of opening of the switching valve based on the target delivery volume and the constant flow rate, and precisely controls the opening and closing of the switching valve to finish quantitative delivery. The technical scheme of the application does not depend on online flow measurement, so that the bubble interference is fundamentally avoided, and the high-precision and high-repeatability quantitative conveying of unstable liquids such as hydrogen peroxide can be realized.

Inventors

  • ZHANG TING
  • ZHENG HUI

Assignees

  • 宁波润华全芯微电子设备有限公司

Dates

Publication Date
20260505
Application Date
20251229

Claims (13)

  1. 1. A dosing system for a liquid, comprising: The buffer tank is used for containing liquid to be conveyed and is provided with a liquid supply pipeline and a conveying pipeline, and the liquid supply pipeline is communicated with an external liquid supply source; The liquid supply valve is arranged on the liquid supply pipeline; The gas control system is communicated with the gas phase space of the buffer tank and can provide a preset stable positive pressure for the buffer tank; A flow restricting element disposed on the delivery line for providing a fixed flow resistance; The switch valve is arranged on the conveying pipeline; And a controller configured to control the liquid supply valve to be in a closed state to isolate the buffer tank from the external liquid supply source when a quantitative delivery operation is performed, and to calculate a duration for which the switching valve needs to be opened based on a preset target transfusion volume and a liquid flow rate determined by the preset stable positive pressure applied to the buffer tank and a fixed flow resistance of the flow restriction element, and to control the switching valve to be opened and then closed according to the calculated duration.
  2. 2. The system of claim 1, wherein the gas control system is further configured to provide a negative pressure into the buffer tank, and wherein the controller is configured to control the gas control system to apply a negative pressure to the gas phase space of the buffer tank to degas the liquid prior to performing the metered delivery operation.
  3. 3. The system of claim 2, further comprising an exhaust line in communication with the vapor space of the buffer tank, and wherein the controller is further configured to control charging of the buffer tank with a predetermined gas after the degassing process, and exhausting the original gas through the exhaust line to perform the gas displacement.
  4. 4. The system of claim 1, wherein the controller compensates for the duration of time the on-off valve is required to open based on the monitored real-time temperature of the liquid.
  5. 5. The system of claim 4, wherein the controller has a table or formula for temperature versus flow rate correction built-in, and is configured to determine a correction factor based on the real-time temperature, correct a reference flow rate value using the correction factor to obtain an actual flow rate corresponding to a current temperature, and calculate the duration based on the actual flow rate.
  6. 6. The system of claim 1, further comprising a load cell disposed below the buffer tank, and wherein the controller is further configured to verify an actual amount of liquid delivered after the on-off valve is closed based on a difference between measurements of the load cell before and after a delivery operation is initiated.
  7. 7. The system of claim 1, wherein the gas control system includes a precision pressure regulating valve for stabilizing the output pressure and a pressure sensor for monitoring the pressure in the surge tank, the controller performing closed loop control of the precision pressure regulating valve by feedback from the pressure sensor to maintain the stable positive pressure.
  8. 8. The system of claim 1, further comprising a level sensor for monitoring the level of liquid in the buffer tank, the controller controlling closing of the liquid supply valve based on a signal of the level sensor to achieve automatic liquid supply.
  9. 9. A method for the quantitative delivery of a liquid, comprising the steps of: supplying the liquid to be conveyed into the buffer tank through a liquid supply pipeline; closing the liquid supply line to isolate the buffer tank from an external liquid supply source prior to performing a dosing operation; Applying a preset stable positive pressure to the gas phase space of the buffer tank; Determining a duration of the delivery operation based on a predetermined target delivery volume and a liquid flow rate determined by the predetermined steady positive pressure applied and a fixed flow resistance in the delivery line; And controlling an on-off valve on the delivery pipeline to be opened and then closed according to the determined duration so as to output the target delivery volume of liquid.
  10. 10. The method of claim 9, further comprising the step of de-gassing the gas phase space of the buffer tank to precipitate gas from the liquid before applying a predetermined steady positive pressure to the gas phase space of the buffer tank.
  11. 11. The method of claim 10, further comprising a gas displacement step of charging an inert gas into the buffer tank to displace evolved gas after the degassing step.
  12. 12. The method of any one of claims 9-11, wherein the liquid is hydrogen peroxide.
  13. 13. A chemical mixing apparatus, comprising: Mixing chamber, and At least two dosing delivery systems, at least one of which is a dosing delivery system according to any one of claims 1-8, the delivery lines of both of which are in communication with the mixing chamber.

Description

Quantitative conveying system and quantitative conveying method for liquid Technical Field The invention relates to the technical field of semiconductor manufacturing equipment, in particular to a quantitative conveying system and a quantitative conveying method for liquid. Background With the development of the semiconductor industry in China, the process level of each large chip manufacturer is also increasing. In order to meet the ever-advancing process requirements, the control over process stability is becoming more stringent. The wet process flow of semiconductor manufacturing is currently the main technical direction for solving the key steps of wafer surface cleaning, etching and the like in the industry. In wet process flows, it is often necessary to mix various chemical liquids, such as concentrated sulfuric acid and hydrogen peroxide, in very strict proportions, precisely to form a process liquid of a specific concentration. Hydrogen peroxide is a commonly used chemical, has unstable chemical properties, is easy to undergo decomposition reaction during storage and transportation, and continuously generates oxygen bubbles. The presence of these bubbles presents a serious technical challenge for achieving high precision quantitative delivery. If the chemical mixture ratio in the mixing process is too large, not only the process result cannot reach the expected value, but also the whole batch of wafers can be scrapped, and serious safety accidents can be caused by wrong chemical reaction. Currently, there are several methods of high precision liquid metering commonly used in the industry. One is an online flowmeter method, but when hydrogen peroxide containing bubbles flows through a sensor, the huge acoustic impedance difference between the bubbles and the liquid can seriously interfere signals, so that the readings of the flowmeter produce violent jitter or even complete errors, and accurate metering cannot be completed. The key to the problem is that the presence of bubbles breaks the physical basis of the measurement, rendering the measurement means itself ineffective. The other is to use a constant displacement pump, but when the liquid containing bubbles is conveyed, the bubbles can absorb a part of the working energy of the pump due to the compressibility of the gas, so that the volume of the liquid actually discharged per stroke of the pump is smaller than a theoretical value, and therefore, a metering error which is difficult to predict is introduced. In a complex industrial equipment environment, various pipelines connected to a liquid storage tank can generate variable stress due to internal pressure change or deformation of the pipelines, and the stress can be directly transmitted to a weighing sensor to form significant interference, so that the accurate and rapid analysis of tiny liquid weight change becomes very difficult. Disclosure of Invention In order to solve the technical problems of low metering precision and poor reliability caused by bubble interference when the existing liquid metering method processes liquid such as hydrogen peroxide which is easy to generate bubbles in the background art, the application provides a quantitative conveying system and a quantitative conveying method for liquid. The technical scheme of the invention provides a quantitative liquid conveying system which comprises a buffer tank, a liquid supply valve, a gas control system, a flow limiting element, a switching valve and a controller, wherein the buffer tank is used for containing liquid to be conveyed and is provided with a liquid supply pipeline and a conveying pipeline, the liquid supply valve is arranged on the liquid supply pipeline, the gas control system is communicated with a gas phase space of the buffer tank and is used for providing preset stable positive pressure for the buffer tank, the flow limiting element is arranged on the conveying pipeline and is used for providing fixed flow resistance, the switching valve is arranged on the conveying pipeline, and the controller is used for controlling the liquid supply valve to be in a closed state and calculating and controlling the opening duration of the switching valve based on a liquid flow rate determined by the preset target infusion volume, the stable positive pressure and the fixed flow resistance. Preferably, the gas control system is further capable of providing a negative pressure into the buffer tank, and the controller performs controlling the gas control system to apply a negative pressure to a gas phase space of the buffer tank to degas the liquid before performing the quantitative transfer operation. Preferably, the apparatus further comprises an exhaust line communicating with the gas phase space of the buffer tank, and the controller is further configured to control filling of a preset gas into the buffer tank after the degassing process is performed, and to discharge the original gas through the exhaust line to perform the