CN1645574A

CN1645574A - Etching liquid recovering system and method

Info

Publication number: CN1645574A
Application number: CN 200510003670
Authority: CN
Inventors: 刘家彰; 李玮华; 吴明杰
Original assignee: AU Optronics Corp
Current assignee: AU Optronics Corp
Priority date: 2005-01-07
Filing date: 2005-01-07
Publication date: 2005-07-27
Anticipated expiration: 2025-01-07
Also published as: CN100431113C

Abstract

The system consists of etching tank used to make etching reaction and hold the wasted liquid formed by etching reaction, the etching solution supply device used to supply the etching solution to the etching tank, the foreign matter removing device used to receive the wasted liquid and remove the impurity from it to form recovering etching solution, the mixed acid and concentration adjusting device used to adjust the mixed acid and concentration for the recovered etching solution.

Description

Etching solution recovery system and method

Technical Field

The invention relates to an etching liquid recovery system and an etching liquid recovery method, and is particularly suitable for an etching process of a thin film transistor liquid crystal display.

Background

Inthin film transistor liquid crystal displays (TFT-LCDs) and semiconductor processes, metals such as aluminum and molybdenum are often used as conductive materials, and wet etching is often used to pattern the metals such as aluminum and molybdenum, and the etching solution can use a variety of different acids, among which the most popular etching solution is a mixed solution of phosphoric acid, nitric acid and acetic acid, and the following reaction mechanism is used:

wherein the nitric acid is effective in providing H₃O⁺The role of (1), etching with oxidized metal; phosphoric acid is used for providing phosphate radicals, so that oxidized metals respectively form complexes with the phosphate radicals; the acetic acid can be attached to the surface of the reactant to inhibit the dissociation of the nitric acid to adjust the etching rate.

As shown in fig. 1, the above-mentioned metal wet etching recycling system firstly supplies the mixed etching solution from the etching solution supply device 11 to the etching tank 10 to perform etching reaction on the metal layer of the glass substrate, and the etching solution will continuously treat a plurality of glass substrates, so that the components and concentration of the etching solution will change, and when the impurity concentration in the etching solution ishigher than a certain level (about 2000ppm) or after a certain number of glass substrates are etched, the etching solution will be completely discharged to the waste solution storage tank 12, and then the outer package treatment 13 is performed.

However, as the number of the glass substrates to be processed increases, the nitric acid in the etching solution is continuously consumed and the impurity concentration is higher, so that the etching effect and the stability are poorer and the variation of the impurity concentration is large (0-2000 ppm); in addition, when the impurity concentration of the etching solution reaches 2000ppm, the etching solution is completely discharged, and then a new etching solution is supplied to the etching tank 10 from the etching solution supply device 11, so that the consumption of the etching solution is large, and the required amount of the etching solution is also large due to the fact that the size of the glass substrate is larger and larger.

Disclosure of Invention

It is therefore an object of the present invention to provide an etching solution recycling system and method to solve the above and other problems and achieve better effects.

To achieve the above object, the present invention provides an etching solution recycling system, comprising: an etching tank for performing an etching reaction, the etching reaction forming a waste liquid containing impurities; an etching solution supply device for supplying an etching solution to the etching bath; the impurity removing device is used for receiving the waste liquid from the etching tank and removing impurities in the waste liquid to form recovered etching liquid; and a mixed acid and concentration adjusting device for performing the mixed acid and concentration adjusting step on the recovered etching solution.

In order to achieve the above object, the present invention further provides a method for recovering an etching solution, comprising: providing an etching solution in an etching tank to perform an etching reaction, wherein the etching reaction forms a waste solution containing impurities; removing impurities in the waste liquid in an impurity removing device to form a recovered etching liquid; carrying out mixed acid and concentration adjustment on the recovered etching solution in a mixed acid and concentration adjustment device; and supplying the recovered etching solution to the etching tank.

Drawings

FIG. 1 is a schematic diagram illustrating a conventional etching solution recycling system;

FIG. 2 is a schematic diagram illustrating an etching solution recycling system according to an embodiment of the invention.

Description of the symbols

10. 20-etching bath 11, 80-etching solution supply device

12. 30-waste liquid storage tank 13-external packing treatment

40-impurity removal device 50-recycled etching solution storage tank

60 portions of mixed acid and concentration adjusting device and 70 portions of etching solution buffer tank

90-monoacid supply device

Detailed Description

In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below:

the following embodiments are provided by way of example of etching aluminum, and the present invention is also applicable to etching molybdenum metal and other metals or metal alloys thereof.

First, an etching solution is supplied from an etching solution supply device 80 to the etching tank 20, wherein the etching solution includes nitric acid, phosphoric acid and acetic acid. Then, placing the glass substrate into an etching tank 20 to perform an aluminum etching reaction; the etched glass substrate is taken out, and then the other glass substrate to be etched is placed into the etching tank 20 for aluminum etching reaction. The above-mentioned steps of etching the glass substrate and replacing the glass substrate are repeated several times until the impurities in the etching solution in the etching bath 20 exceed a certain concentration or a certain number of glass substrates are treated, and then the resulting waste liquid containing aluminum impurities is discharged partially or completely to the waste liquid storage tank 30, wherein the impurity concentration of the waste liquid containing aluminum impurities when the waste liquid is discharged can be determined according to different requirements, such as maximum impurity limit, predetermined range of impurity concentration, and discharge amount (ratio) of the waste liquid containing aluminum impurities. If the timing of discharging the aluminum-containing waste liquid is determined based on the number of treated glass substrates, the number of the glass substrates can be determined by experiment and/or result statistics. Generally, when the concentration of impurities is smaller or the number of processed glass substrates is smaller, i.e., when the waste liquid containing aluminum impurities is partially or completely discharged, the etching effect is better, but the production and acid exchange time is increased, and the overall production efficiency is reduced.

When the waste liquid containing aluminum impurities in the waste liquid storage tank 30 is stored to a certain volume, the waste liquid is discharged into the impurity removing device 40.

In the impurity removing device 40, impurities in the waste liquid containing aluminum impurities can be removed to a certain extent to form a recovered etching liquid, and then the recovered etching liquid is discharged into a recovered etching liquid storage tank 50; the impurity removing device 40 may include an ion exchange membrane to remove impurities, for example, in an environment with a pH of 1.0, the etching solution containing aluminum impurities originally containing 73.1ppm of aluminum impurities is treated by the ion exchange membrane to obtain a recycled etching solution containing only 6ppm of aluminum impurities. Generally, the recovery rate of the etching solution is 80% or more, and approximately 80 to 90%.

Since phosphoric acid and aluminum form a complex when the etching solution is subjected to the aluminum etching step, phosphoric acid in the etching solution is lost, and nitric acid and acetic acid are also lost due to the etching treatment, the impurity removal treatment, and the like, so that the recovered etching solution must be reconditioned to be supplied to the etching bath 20 again; the recovered etching solution in the recovered etching solution storage tank 50 is discharged into the mixed acid and concentration adjustment device 60, after the concentration of each acid is measured, the nitric acid supplier, the phosphoric acid supplier and the acetic acid supplier in the single acid supplier supplement the respective acid which is lacked, so as to adjust the concentration of each acidic material in the recovered etching solution to the range capable of etching, and after mixing, the recovered etching solution is discharged into the etching solution buffer tank 70, and the buffer tank 70 is used for storing the etching solution with the concentrationadjusted to wait for the requirement of the process equipment; then, the recovered etching solution is discharged into an etching tank for etching treatment.

The etching solution recovery system can be used for recovering after removing impurities in the waste liquid, and the recovery rate can reach more than 80 percent, so that the consumption of the etching solution can be greatly reduced, and the aims of saving cost and protecting environment are fulfilled; in addition, the etching solution recovery system can control the concentration of impurities in the etching solution to be in a stable range, thereby reducing the variation of etching reaction to increase the process stability; furthermore, the structure of the etching solution recovery system of the present invention can be obtained by combining other devices in the existing system, i.e., without replacing the existing system.

Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. An etching solution recovery system, comprising:

an etching tank for performing an etching reaction, wherein the etching reaction forms a waste liquid containing impurities;

an etching solution supply device for supplying an etching solution to the etching tank;

an impurity removing device for receiving the waste liquid and removing impurities in the waste liquid to form a recovered etching liquid; and

a mixed acid and concentration adjusting device, which performs a mixed acid and concentration adjusting step on the recycled etching solution.

2. The etching solution recovery system of claim 1, wherein the impurity removal device comprises an ion exchange membrane.

3. The etching solution recovery system of claim 1, further comprising a single acid supply system, wherein the single acid supply system comprises a phosphoric acid supplier, a nitric acid supplier and an acetic acid supplier for supplying phosphoric acid, nitric acid and acetic acid to the mixed acid and concentration adjustment device and the etch bath, respectively.

4. The etching solution recovery system according to claim 1, further comprising:

a waste liquid storage tank for receiving the impurity-containing waste liquid from the etching tank and discharging the impurity-containing waste liquid to the impurity removing device;

a recovered etching solution storage tank for receiving the recovered etching solution from the impurity removing device and discharging the recovered etching solution to the mixed acid and concentration adjusting device; and

an etching solution buffer tank for receiving the recovered etching solution from the mixed acid and concentration adjusting device and discharging the recovered etching solution to the etching tank.

5, an etching solution recovery method comprises the following steps:

providing an etching solution in an etching tank to perform an etching reaction, wherein the etching reaction forms a waste solution containing impurities;

removing impurities in the waste liquid in an impurity removingdevice to form a recovered etching liquid;

performing a mixed acid and concentration adjustment step on the recovered etching solution in a mixed acid and concentration adjustment device; and

supplying the recovered etching solution to the etching tank.

6. The method of claim 5, wherein the etching reaction comprises an etching aluminum reaction, the waste solution comprises an etching solution containing aluminum impurities and the impurities comprise aluminum complexes.

7. The method of claim 5, wherein the etching reaction comprises an etching molybdenum reaction, the waste solution comprises an etching solution containing molybdenum impurities and the impurities comprise molybdenum complexes.

8. The method of claim 5, wherein the step of removing impurities from the waste solution is performed by using an ion exchange membrane.

9. A method for recovering etching solution according to claim 5, wherein the volume of the recovered etching solution is about 80-90% of the volume of the waste solution.

10. The method of claim 5, further comprising collecting the waste solution from the etching chamber into a waste solution storage tank, and discharging the waste solution from the waste solution storage tank to the impurity removing device.

11. The method according to claim 5, further comprising collecting the recovered etchant from the impurity removing device into a recovered etchant storage tank, and discharging the recovered etchant from the recovered etchant storage tank to the mixed acid and concentration adjusting device.

12. The method of claim 5, wherein the step of mixing acid and adjusting concentration is adding and mixing an acidic material selected from the group consisting of phosphoric acid, nitric acid, acetic acid and combinations thereof, and the acidic material is provided by a single acid supply system comprising a plurality of single acid suppliers.

13. The method according to claim 5, further comprising collecting the recovered etching solution from the mixed acid and concentration adjusting device into an etching solution buffer tank, and discharging the recovered etching solution from the etching solution buffer tank into the etching tank.