KR20050078901A - System for controlling mixing chemicals concentration having a zero point compensation unit - Google Patents

Abstract

Provide a mixed chemical solution concentration control system. The present invention compares the concentration detection sensor that detects the concentration of the chemical solution flowing into the flow cell and outputs it as an electrical detection signal, and the detection signal output from the concentration detection sensor with the concentration data of the reference chemical solution input in advance. A controller that calculates the concentration of the mixed chemical solution and outputs a control signal for controlling the concentration of the mixed chemical solution at a predetermined concentration, and is connected to the controller, and compensates zero if the zero of the concentration detection sensor is not normal. A zero compensation unit is provided. Accordingly, the present invention can maintain the constant by automatically adjusting the concentration of the mixed chemical solution to a user-set concentration to compensate if the zero of the concentration detection sensor is normal, as it is normal.

Description

System for controlling mixing chemicals concentration having a zero point compensation unit

The present invention relates to a mixed chemical solution concentration control system, and more particularly to a mixed chemical solution concentration control system capable of maintaining a constant concentration of the mixing chemicals (mixing chemicals) used in the manufacture of semiconductor devices.

In the manufacture of a semiconductor device, a mixed chemical solution is used in a cleaning process, an etching process and a stripping process. The mixed chemical solution is used by mixing deionized water with a high concentration of a chemical solution such as a hydrofluoric acid solution, a phosphoric acid solution and the like at a constant concentration ratio. When the mixed chemical solution is used in the manufacturing process of the semiconductor device, the concentration change of the mixed chemical solution occurs by evaporation of deionized water.

In particular, in the wet etching process used in the manufacture of the semiconductor device, since the process temperature exceeds 100 ° C., which is the vaporization point of water, moisture contained in the mixed chemical solution is easily evaporated, and the concentration of the mixed chemical solution is severely changed.

By the way, the prior art extracts the mixed chemical solution contained in the mixed chemical solution bath during the semiconductor manufacturing process using the mixed chemical solution to measure the concentration with a concentration detection sensor, and then to the mixed chemical solution bath according to the measured concentration Deionized water was added to adjust the concentration of the mixed chemical solution. In this case, it is impossible to automatically control the concentration value obtained by the concentration detection sensor to be used for the concentration adjustment.

Therefore, the technical problem to be achieved by the present invention is to provide a mixed chemical solution concentration control system that can be measured in real time by continuously measuring the concentration of the mixed chemical solution by an automatic control method.

In order to achieve the above technical problem, the mixed chemical solution concentration control system according to an embodiment of the present invention is a mixed chemical solution bath containing the mixed chemical solution, a circulation pipe connected to the mixed chemical solution bath, and the circulation pipe A standard chemical solution bath is installed. The circulation pipe is provided with a flow cell, and a concentration detection sensor is provided for detecting the concentration of the chemical solution flowing into the flow cell and outputting it as an electrical detection signal.

Computing the concentration of the mixed chemical solution by comparing the detection signal output from the concentration detection sensor with the concentration data of the reference chemical solution input in advance, and outputs a control signal for controlling the concentration of the mixed chemical solution at a predetermined concentration The controller is installed. And a zero compensation unit connected to the controller and configured to compensate the zero point when the zero point of the concentration detection sensor is not normal.

Each solenoid valve is controlled according to a control signal output from the controller to adjust the flow rate of the high concentration chemical solution and deionized water flowing into the mixed chemical solution bath.

In addition, the mixed chemical solution concentration control system according to another embodiment of the present invention is a mixed chemical solution bath that can accommodate a mixed chemical solution, a circulation pipe connected to the mixed chemical solution bath, and a reference chemical solution bath connected to the circulation pipe Is installed.

A flow cell is provided in the circulation pipe at the rear end of the reference chemical solution, and a concentration detection sensor is provided that detects the concentration of the chemical solution flowing into the flow cell and outputs it as an electrical detection signal.

Computing the concentration of the mixed chemical solution by comparing the detection signal output from the concentration detection sensor with the concentration data of the reference chemical solution input in advance, and outputs a control signal for controlling the concentration of the mixed chemical solution at a predetermined concentration The controller is installed.

A zero point compensator connected to the controller and capable of compensating zero if the zero point of the concentration detection sensor is not normal, and opened and closed according to a control signal output from the controller to be introduced into the mixed chemical solution bath. Each solenoid valve is installed to regulate the inflow of high concentration chemical solution and deionized water.

A display unit connected to the controller and displaying the calculated concentration of the mixed chemical solution, a display unit connected to the zero point compensator, and a zero point of the concentration detection sensor connected to the display unit and connected to the display unit and the zero point compensator. And an input unit for inputting a corrected value.

As described above, the present invention is provided with a zero compensation unit capable of compensating the zero of the concentration detection sensor as it is when the zero is normal, and compensates when the zero is not normal to automatically adjust the concentration of the mixed chemical solution to a user-set concentration. Can be kept constant.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention; However, embodiments of the present invention illustrated below may be modified in many different forms, and the scope of the present invention is not limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

1 is a block diagram of a mixed chemical solution concentration control system according to the present invention.

Specifically, the mixed chemical solution concentration control system is connected to the mixed chemical solution bath 20, the mixed chemical solution bath 20 is circulated to circulate the mixed chemical solution contained in the mixed chemical solution bath 20 Piping 24.

The circulation pipe 24 is used to remove impurities in the mixed chemical solution 22 contained in the mixed chemical solution bath 20. The mixed chemical solution 22 is overflowed to the overflow receiving portion 26 formed at the upper end of the mixed chemical solution bath 20 and the compressor C, the filter FL, and the first using the circulation pipe 24. It is supplied to the mixed chemical solution bath 20 again through the valve V1, the second valve V2, and the like.

The circulation pipe 24 connected to the mixed chemical solution bath 20 is provided with a supply pipe 34 capable of supplying the reference chemical solution 32. The supply pipe 34 is provided with a third valve V3 and a reference chemical solution bath 30 to supply the reference chemical solution 32. The circulation pipe 40 is provided with a discharge port 3 provided with a fourth valve V4 so as to discharge the reference chemical solution 32 when the concentration of the reference chemical solution 32 is measured.

The circulation pipe 24 is provided with a tubular flow cell 40 made of a light transmitting agent. The flow cell 40 is made of transparent sapphire, synthetic resin, or glass material. A concentration that detects and outputs a concentration of the mixed chemical solution 22 or the reference chemical solution 32 that flows into the flow cell 40 adjacent to the flow cell 40 as an electrical signal using light having a specific wavelength. The detection sensor 50 is provided.

The concentration detection sensor 50 calculates the concentration of the mixed chemical solution 22 by comparing the detection signal (concentration data) output from the concentration detection sensor 50 with the concentration data of the reference chemical solution 32 stored in advance. And a controller 60 for outputting a control signal for controlling the concentration of the mixed chemical solution 22 at the set concentration.

The controller 60 is connected to a solenoid valve SV1 and SV2 for controlling the inflow of the high concentration chemical solution and deionized water introduced into the mixed chemical solution bath 20 by being controlled to open and close according to the control signal of the controller 60. It is. The controller 60 is connected to a display unit 68 capable of displaying the concentration of the mixed chemical solution 22 or the reference chemical solution 32. The display unit 68 is connected to an input unit 66 for inputting data.

The controller 60 is connected to a zero compensator 70 capable of compensating the zero of the concentration detection sensor 50. The controller 60 corrects the zero point in the zero point compensator 70 through the input unit 66 and the display unit 68 before outputting the control signal when the zero point of the concentration detection sensor is not normal. The corrected control signal is transmitted to the solenoid valves SV1 and SV2 which respectively control the inflow amounts of the high concentration chemical solution and the deionized water flowing into the mixed chemical solution bath. In Fig. 1, reference numerals 28a and 28b denote supply pipes for supplying a high concentration chemical solution and deionized water, respectively. The method for determining whether the zero point of the concentration detection sensor is normal will be described later in detail.

FIG. 2 is a diagram for describing the concentration detection sensor of FIG. 1 in detail. In Fig. 2, the same reference numerals as in Fig. 1 denote the same members.

Specifically, the concentration detection sensor applied to the present invention is a transmitter 52 for emitting light of a predetermined wavelength toward the flow cell 40, and is emitted from the transmitter 52 and transmitted to the flow cell 40 And a photodetector 54 for introducing light.

In order to minimize scattering and refraction of the light, the flow cell 40 has a plane of incidence and exit of the light irradiated from the concentration detection sensor 50 to ensure the accuracy of light detection. The flow cell 40 may be provided with a heater 46 for temperature control, in which case a temperature controller 47 is required to remove the heat generation of the heater 46, the temperature controller 47 is It can be built in the controller 60 and configured. The photodetector 54 is provided with a filter 54a that can filter light having a desired specific wavelength on its front surface.

A chopper 56 having a plurality of floodlight holes is installed between the transmitter 52 and the flow cell 40. The chopper 56 is shot on or shut off at predetermined intervals according to the operation of the actuator 58 controlled by the controller 60 to transmit the light to the flow cell 40. It is configured to connect or block it. The transmitter 52 is configured to emit light having a specific wavelength for detecting the concentration of the mixed chemical solution or the reference chemical solution. The light emitting source is selected differently according to the type of chemical solution.

The controller 60 continuously introduces a measurement signal of the concentration of the mixed chemical solution detected from the photodetector at a predetermined period to calculate the concentration of the mixed chemical solution based on the concentration data of the reference chemical solution. That is, the controller 60 shuts down the chopper 56 to introduce a concentration measurement signal detected by the photodetector 54, and simultaneously accesses, compares and computes the concentration data of the reference chemical solution, thereby concentrating the concentration of the mixed chemical solution. The measured data are obtained and displayed on the display unit 68, and the opening and closing of the solenoid valves SV1 and SV2 are controlled until the desired concentration is detected in the mixed chemical solution. The setting of the concentration of the mixed chemical solution and the operation of the system may be set by the user through the input unit 66.

The mixed chemical solution concentration control system of the present invention configured as described above is constituted based on the technical basis of Lambert-Berber law, in which the absorbance varies depending on the concentration of the medium. In particular, the mixed chemical solution concentration control system of the present invention can be used to maintain the mixed chemical solution at a desired concentration in a process using a mixed chemical solution, such as a cleaning process or an etching process in the manufacture of a semiconductor device. Hereinafter, a description will be given with reference to FIGS. 1 to 5.

3 and 4 are graphs showing the absorption spectra of deionized water and phosphoric acid according to the present invention, respectively, and FIG. 5 is a graph showing the absorbance versus the concentration of phosphoric acid at a wavelength of 1200 nm according to the present invention.

Specifically, the present invention contains various reference chemical solutions 32 used in the semiconductor manufacturing process in the reference chemical solution bath 30 to close the first valve V1 connected to the mixed chemical solution bath 20 and close the reference chemistry. The third valve V3 connected to the solution bath 30 is opened to prepare a concentration reference using the concentration detection sensor 50.

First, the absorption spectrum of deionized water was observed using deionized water always present in the mixed chemical solution 22 as a reference chemical solution. This experiment is performed because the relative concentration of the mixed chemical solution 22 can be analyzed by first knowing the absorption characteristics of deionized water.

As a result of scanning between 800 nm and 1500 nm wavelength which is a near infrared region, the light absorption characteristic as shown in FIG. 3 was obtained. According to these results, it can be seen that deionized water exhibits strong absorption characteristics in the visible region and continues to about 1350 nm. The absorption characteristics of the deionized water have a great influence on the degree of absorption of the mixed chemical solution. Therefore, the concentration characteristics of the deionized water should be adjusted based on the deionized water.

After the experiment of measuring the absorbance of deionized water as described above, 15%, 50%, 85% phosphoric acid was prepared as an example of the reference chemical solution and the degree of absorption was tested. As shown in FIG. It was confirmed that the absorbance is proportional to the concentration in two wavelength bands from 1130nm to 1400nm. Accordingly, as a result of measuring the absorption relations with the graphs by measuring the phosphoric acid at various concentrations at a wavelength of 1200 nm, as shown in FIG. 5, the change is proportional to the concentration change, and the straightness of the change is good. Could confirm. Therefore, when measuring the concentration of the mixed chemical solution containing phosphoric acid it can be seen that the 1200nm wavelength light is most suitable.

In this manner, a concentration standard is prepared by using a chemical solution 32 other than phosphoric acid, such as hydrofluoric acid, ammonia, and hydrogen peroxide. The concentration data measured using the reference chemical solution is stored in the internal memory of the controller 60 connected to the concentration detection sensor 50 and used as basic data to be used for subsequent concentration control of the mixed chemical solution 22.

Hereinafter, the mixed solution concentration control method of the mixed chemical solution concentration control system according to the present invention will be described.

First, it is measured whether or not the zero point of the concentration detection sensor 50 is normal. To this end, after receiving deionized water in the mixed chemical solution bath 20, the first valve V1 is turned on to supply deionized water to the flow cell 40. Next, the deionized water supplied to the flow cell 40 is detected by using the concentration detection sensor 50 and output to the display unit.

If the concentration value of the deionized water output to the display unit is 100wt% and the concentration value of the remaining nutrient solution is 0Wt%, it is determined that the zero point of the concentration detection sensor is normal. If the concentration value of the deionized water output to the display unit is 100wt%, and the concentration value of the A chemical solution contained in the mixed chemical solution is 5wt%, the zero point of the A chemical solution is changed to -5wt%. When the concentration value of the deionized water output to the display unit is 95Wt% and the concentration value of the A chemical solution contained in the mixed chemical solution is 0Wt%, the zero point of the deionized water is changed to + 5wt%.

In the present embodiment, deionized water was used to check the zero point, but even if it is not deionized water, another solution may be used if the mass ratio of one compound is kept at 100 wt% purely.

As described above, when zero or more is confirmed, the zero point of the concentration detection sensor 50 is directly compensated using zero adjustment software, or data from the mixed concentration detection system is inputted to the input unit 66, the display unit 68, and zero compensation. Compensation to the controller 60 through the unit 70. That is, the correction value capable of correcting the zero point as described above is compensated to the controller 60 through the display unit 68 and the zero compensator 70 by inputting the input value through the input unit 66. According to the compensated value, the controller 60 adjusts the amount of high concentration chemical solution or deionized water injected into the mixed chemical solution bath 20 to maintain a constant concentration of the mixed chemical solution.

On the other hand, in the actual process, the mixed chemical solution which overflows to the overflop accommodating part 26 using the density | concentration detection sensor, and circulates the circulation piping 24 by opening of the 1st valve V1 and the 2nd valve V2. A photodetector 22 is used to transmit this detection signal (concentration data) to the controller. The controller 60, which secures the concentration data of the base by the reference chemical solution, compares and calculates the concentration data detected by the photodetector 54 with the concentration data of the base to determine the concentration of the mixed chemical solution 22 currently measured. Deduce the concentration value.

If the zero point of the concentration detection sensor 50 is normal, it is compensated if it is not normal, and if the derived concentration value is different from the concentration value previously set by the process manager, the set concentration value and the derived concentration value The operation of the solenoid valves SV1 and SV2 installed in each supply line is controlled to supply more deionized water or a higher concentration of chemical solution.

For example, if the measured concentration of the mixed chemical solution 22 is less than the concentration value set by the user, the solenoid valve SV1 of the high concentration chemical solution supply pipe 28a is opened until the same, and vice versa. In this case, the solenoid valve SV2 of the deionized water supply pipe 28b is opened.

As described above, the mixed chemical solution concentration control system of the present invention includes a zero compensation unit capable of compensating the zero of the concentration detection sensor as it is when the zero point is normal, and compensates when the zero point is not normal to a user-set concentration. The concentration of the mixed chemical solution can be automatically adjusted to keep it constant.

In other words, the mixed chemical solution concentration control system of the present invention sets the upper and lower concentration limits of the mixed chemical solution, and includes a zero compensation unit capable of compensating the zero of the concentration detection sensor. If not, the concentration of the mixed compound can be maintained by compensating and supplying insufficient chemicals only when the lower limit is exceeded, and when not exceeding the upper limit.

1 is a block diagram of a mixed chemical solution concentration control system according to the present invention,

FIG. 2 is a diagram for describing the concentration detection sensor of FIG. 1 in detail;

3 and 4 are graphs showing the absorption spectra of deionized water and phosphoric acid according to the present invention, respectively,

5 is a graph showing the absorbance versus the concentration of phosphoric acid at a wavelength of 1200 nm according to the present invention.

Claims (4)

Mixed chemical solution bath containing mixed chemical solution; A circulation pipe connected to the mixed chemical solution bath; A reference chemical solution bath connected to the circulation pipe; A flow cell installed in the circulation pipe; A concentration detection sensor that detects a concentration of the chemical solution flowing into the flow cell and outputs the electrical detection signal; Computing the concentration of the mixed chemical solution by comparing the detection signal output from the concentration detection sensor with the concentration data of the reference chemical solution input in advance, and outputs a control signal for controlling the concentration of the mixed chemical solution at a predetermined concentration Controller; A zero compensation unit connected to the controller and configured to compensate zero if the zero of the concentration detection sensor is not normal; And Mixed solenoid valve concentration control system, characterized in that each of the solenoid valve controlled in accordance with the control signal output from the controller to adjust the flow rate of the high concentration chemical solution and deionized water flowing into the mixed chemical solution bath. The mixed chemical solution concentration control system according to claim 1, wherein the controller is provided with a display unit for displaying the concentration of the mixed chemical solution. The mixed chemical solution concentration control system according to claim 1, wherein the display unit is connected to an input unit for inputting data for compensating zero point. Mixed chemical solution baths capable of containing mixed chemical solutions; A circulation pipe connected to the mixed chemical solution bath; A reference chemical solution bath connected to the circulation pipe; A flow cell installed in the circulation pipe at a rear end of the reference chemical solution; A concentration detection sensor that detects a concentration of the chemical solution flowing into the flow cell and outputs the electrical detection signal; Computing the concentration of the mixed chemical solution by comparing the detection signal output from the concentration detection sensor with the concentration data of the reference chemical solution input in advance, and outputs a control signal for controlling the concentration of the mixed chemical solution at a predetermined concentration Controller; A zero compensation unit connected to the controller and configured to compensate zero if the zero of the concentration detection sensor is not normal; Each solenoid valve opened and controlled according to a control signal output from the controller to adjust an inflow amount of a high concentration chemical solution and deionized water introduced into the mixed chemical solution bath; A display unit connected to the controller and configured to display the calculated concentration of the mixed chemical solution and connected to a zero point compensator; And And an input unit connected to the display unit and configured to input a correction value for compensating the zero point of the concentration detection sensor through the display unit and the zero compensator.