CN1884631A - Method and device for cleaning organic matter using electrochemical method - Google Patents

Abstract

The invention discloses a method and a cleaning device for cleaning organic matter by using an electrochemical method. The method is characterized in that the diamond membrane electrode is used as an anode, and the organic matter is cleaned electrochemically in the range of current density 100-5000Am ^-2 . The invention makes full use of the advantages of the diamond film electrode in electrochemical oxidation technology, and uses the diamond film electrode to generate strong oxidizing particles such as hydroxyl radicals and oxygen free radicals, which can be used for organic cleaning, for example: for cleaning photoresist and stripping semiconductor devices to avoid A certain amount of heavy metals and alkali metal elements in the traditional wet process can be eliminated, which can meet the requirements of device design; it can be used for activated carbon regeneration, which can greatly reduce the cost and will not cause environmental pollution. The invention utilizes the diamond membrane electrode for organic cleaning with simple equipment, easy operation and no secondary pollution. It consumes less energy and meets the requirements of low-cost manufacturing and environmental protection.

Description

Method and device for cleaning organic matter by electrochemical method

【Technical field】

The invention relates to the field of electrochemical oxidation, in particular to a method and a device for cleaning organic matter by using an electrochemical method.

【Background technique】

Advanced oxidation processing (AOP) technology is widely used to degrade or decompose organic matter, especially refractory organic pollutants. At present, electrochemical oxidation treatment plays a very important role in the treatment of industrial wastewater, and the oxidation process has attracted more and more attention in reducing toxic pollution. At the same time, the use of electrochemical oxidation to treat photoresist stripping and activated carbon regeneration on semiconductor devices has also attracted more and more attention.

In the semiconductor device manufacturing process, photoresist stripping generally adopts plasma ashing and wet process. In most cases, wet cleaning is performed after ashing to remove organic or polymer residues from the plasma process. The solution used for wet cleaning is generally a mixture of SPM-APM, where the SPM solution is a mixture of sulfuric acid (H ₂ SO ₄ ) and hydrogen peroxide (H ₂ O ₂ ), and the APM solution is a mixture of ammonium hydroxide, hydrogen peroxide and water. mixture. Both the traditional chemical cleaning reagents SPM and APM contain metal ion impurities, which have a negative impact on the electrical properties of the new gate structure; It is disposable, making the cleaning cost very high; in addition, the use of traditional chemical reagents and water consumption have a negative impact on the environment.

Activated carbon is a non-toxic, odorless, excellent adsorbent with a well-developed pore structure and a large specific surface area. In the prior art, a large number of activated carbon adsorption methods are used to treat urban drinking water and industrial wastewater, carbon disulfide wastewater treatment, and oil refining wastewater, explosive wastewater, printing and dyeing wastewater, chemical wastewater and electroplating wastewater treatment. With the widening of the application range of activated carbon, the recovery of activated carbon has begun to get people's attention. If the used activated carbon cannot be recycled, in addition to increasing the treatment cost per ton of wastewater, it will also cause secondary pollution to the environment. Therefore, the regeneration of activated carbon is of great significance. Traditional activated carbon regeneration methods include thermal regeneration, biological regeneration and other traditional methods of activated carbon regeneration. At the same time, emerging activated carbon regeneration technologies include supercritical fluid method, catalytic wet oxidation method and ultrasonic method.

【Content of invention】

The purpose of the present invention is to solve the problems of the prior art, and provide a method and device for cleaning organic matter by electrochemical method. The method utilizes the advantages of diamond film electrode in electrochemical oxidation, and directly cleans the object to be cleaned with electrolyte The organic matter on the surface is significantly better than other electrodes used in electrochemical water treatment.

To realize the purpose of the invention, the invention discloses a method for cleaning organic matter by using an electrochemical method. It is characterized in that the cleaning object containing organic matter is placed in the electrolyte; the diamond film electrode is used as the anode, and the hydroxyl group (OH ^- ) in the water is electrochemically oxidized in the range of current density 100-5000Am ^-2 to generate hydroxyl radical (OH· ) oxygen radicals (O·), ozone (O ₃ ), and hydrogen peroxide (H ₂ O ₂ ).

The invention also discloses an electrochemical cleaning device specially used for cleaning organic matter by electrochemical methods, including an electrolytic cell, an electrode, and an ion membrane. Compartment electrolytic cells, double-compartment and multi-compartment electrolytic cells are separated by ionic membranes; the electrodes have one or more groups, and each group of electrodes consists of anode-diamond film electrodes and cathode-common metal electrodes, adjacent to each other. The distance between the anode and the cathode is 0.5-50mm; at the same time, the disturbance of the electrolyte is realized by mechanical means.

The invention fully utilizes the advantages of the diamond film electrode in the electrochemical oxidation technology, and exerts the application potential of the diamond film electrode. The use of diamond film electrodes to generate oxidized particles such as hydroxyl radicals and oxygen radicals can be used for organic cleaning, for example: used to clean photoresists and strip semiconductor devices, avoiding a certain amount of heavy metals and alkali metal elements in traditional wet processes, and can Meet the requirements of device design; used for activated carbon regeneration, can greatly reduce the cost, and will not cause environmental pollution. The invention utilizes the diamond membrane electrode for organic cleaning with simple equipment, easy operation and no secondary pollution. It consumes less energy and meets the requirements of low-cost manufacturing and environmental protection.

【Description of drawings】

Figure 1 Schematic diagram of the electrochemical cleaning device.

In the figure: 1. Anode; 2. Cathode; 3. Water pump; 4. Container; 5. Flow meter; 6. Power supply.

【Detailed ways】

The present invention uses an electrochemical method to clean organic matter. The cleaning object is placed in an electrolyte, and a diamond film electrode is used as an anode to electrochemically oxidize hydroxyl (OH ^- ) in water to generate hydroxyl in the range of current density 100-5000Am ^-2 Free radicals (OH·) oxygen radicals (O·), ozone (O ₃ ), and hydrogen peroxide (H ₂ O ₂ ).

The electrochemical cleaning device of the present invention is composed of an electrolytic cell, an electrode, an ion membrane, a flow meter 5, a power source 6 and the like. The electrolytic cell is a single-compartment electrolytic cell or a double-compartment or multi-compartment electrolytic cell. The cathode tank and the anode tank are separated by an ionic membrane in the middle of the electrolytic cells of the double-compartment and multi-compartment electrolytic cells. Said electrodes can have one or more groups, each electrode group is composed of anode-diamond film electrode and cathode-ordinary metal electrode, the distance between adjacent anode 1 and cathode 2 electrodes is 0.5-50mm, and the electrodes are fixed in the in the slot. The connection of multiple sets of electrode groups can be connected in parallel or in series. In order to improve the cleaning efficiency, the disturbance or circulation of the electrolyte can be realized by setting the water pump 3 or the agitator.

For the convenience of cleaning certain cleaning objects or for cleaning a large number of cleaning objects, the electrolytic cell can also be connected to a cleaning object container 4 through a circulation pipeline and a circulation pump. That is to say, the cleaning object is placed in the container, and the electrolyte is introduced into the cleaning container through the circulation pipeline, and it can continuously circulate with the electrolyte in the electrolytic cell. For example, the container is used to contain the activated carbon polluted by organic matter, and the activated carbon is regenerated. When the electrolytic cell is a double-compartment or multi-compartment electrolytic cell, the circulation pipeline communicates with the anode tank.

The present invention can perform organic cleaning on the photoresist stripped semiconductor device as the cleaning object. Place the device to be cleaned organically into the single-compartment electrolytic cell, or into the anode tank if it is a double-compartment or multi-compartment electrolytic cell. The electrode group electrolyzes water through direct current, and the cleaning efficiency is controlled by controlling the magnitude of the current. The higher the current density, the higher the efficiency, and the current density range is between 100-5000Am ^-2 .

In the present invention, activated carbon polluted by organic substances can also be used as the cleaning object to perform activated carbon regeneration cleaning. Use single or multi-chamber electrolytic cell processors to electrolyze water, and use water pumps to realize water circulation between processors and activated carbon containers. The higher the current density, the higher the processing efficiency, and the current density range is between 100-5000Am ^-2 .

The working principle of the present invention utilizing the electrochemical method to clean organic matter is: when the diamond film electrode is used as the anode to electrolyze water, since the oxygen evolution potential of the diamond film electrode is very high, the electrode potential (>+3V) of the diamond will not be released when oxygen is released. A large number of hydroxyl radicals (OH ) can be generated on the electrode surface S:

S is on the surface of the anode, and S(HO·) is the hydroxyl radical (OH·) on the electrode surface. On a general reaction electrode, the adsorbed HO will passivate the electrode, but on a relatively stable electrode, such as a diamond film electrode, the adsorbed S(HO ) will be oxidized to generate oxygen:

Oxygen can be further oxidized to O3 by hydroxyl radicals on the electrode surface,

In addition to O ₃ , S(HO.) generates H ₂ 0 ₂ by combining

Hydroxyl radicals, as well as particles such as ozone, are highly oxidizing, which is important for effective photoresist stripping and organic cleaning. Hydroxyl radicals are the key to organic cleaning. Activated carbon regeneration is to remove organic waste adsorbed on the surface of activated carbon. High-strength oxidizing agents such as oxygen radicals (O·), ozone (O ₃ ), hydrogen peroxide (H ₂ O ₂ ) and hydroxyl radicals (OH·) can Realize the oxidation and removal of these organic substances, so as to realize the regeneration of activated carbon.

Example 1: Apply high-temperature paraffin evenly on a polished silicon wafer with a thickness of 1mm, and then put it into a single-electrode group single-compartment electrolytic cell processing device, the distance between adjacent negative and positive electrodes is 1mm, the voltage is 10V, and the current is 2.5 A, the current density is around 1000Am ^-2 . After 1 hour of treatment, the paraffin wax has obvious shedding phenomenon, and after 2 hours, the paraffin wax all falls off without residue.

Example 2: Apply high-temperature paraffin evenly on a polished silicon wafer with a thickness of 1mm, and then put it into the anode tank of the single-electrode group double-chamber electrolytic cell processing device, the distance between adjacent cathode and anode electrodes is 2mm, the voltage is 13V, and the current 2.5A, the current density is around 1000Am ^-2 . After 0.5 hours of treatment, the paraffin wax has obvious shedding phenomenon, and after 70 minutes, the paraffin wax all falls off without residue.

Embodiment 3: Apply high-temperature paraffin evenly on the polished silicon wafer with a thickness of 1 mm, and then put it into a multi-electrode group single-compartment electrolytic cell processing device, the distance between adjacent negative and positive electrodes is 1 mm, the voltage is 10 V, and the current is 100 A. The current density is around 7000Am ^-2 . After 2 minutes of treatment, the paraffin wax obviously fell off, and after 10 minutes, the paraffin wax completely fell off without residue.

Embodiment 4: Put saturated activated carbon into the container, connect the single-compartment multi-electrode group electrochemical oxidation processor to the container, the distance between adjacent cathode and anode electrodes is 0.5mm, and use a pump to realize water circulation between the device and the container. Connect direct current, the voltage is 10V, the current is 5A, and the current density is around 1000Am ^-2 . After 5 hours of cleaning, the activated carbon was taken out from the container, and it was tested that the activity of the activated carbon returned to its original state.

Claims (8)

1. A method for cleaning organic matter by an electrochemical method is characterized in that a cleaning object containing the organic matter is placed in an electrolyte; using diamond film electrode as anode, at current density of 100-5000Am^-2In the range between electrochemical Oxidation of Hydroxyl (OH) groups in water^-) Generating hydroxyl free radical (OH) and oxygen free radical (O), ozone (O)₃) And hydrogen peroxide (H)₂O₂)。

2. An electrochemical cleaning apparatus for use in a method of electrochemically cleaning organic matter according to claim 1, comprising an electrolytic cell, electrodes, and an ionic membrane, wherein said electrolytic cell is a single-compartment electrolytic cell or a two-compartment or multi-compartment electrolytic cell, and the electrolytic cells of the two-compartment and multi-compartment electrolytic cells are separated by the ionic membrane; the electrodes are one or more groups, each group of electrode group consists of an anode-diamond membrane electrode and a cathode-common metal electrode, and the distance between two adjacent electrodes of the anode and the cathode is 0.5-50 mm; and meanwhile, the disturbance of the electrolyte is realized by a mechanicalmode.

3. An electrochemical cleaning device according to claim 4, wherein the electrolyte in said electrolytic cell is connected to a container for objects to be cleaned through a circulation line and a circulation pump.

4. An electrochemical cleaning device according to claim 4 or 5, wherein said electrolytic cell is a two-compartment or multi-compartment electrolytic cell and the circulation line is in communication with the anode tank.

5. An electrochemical cleaning device according to claim 4 or 5, wherein said plurality of electrode sets are connected in parallel or in series.

6. An electrochemical cleaning device according to claim 6, wherein said plurality of electrode sets are connected in parallel or in series.

7. An electrochemical cleaning device according to claim 4 or 5 or 8, wherein said disturbance of the electrolyte is achieved mechanically by means of a pump or agitator.

8. An electrochemical cleaning device according to claim 7, wherein said disturbance of the electrolyte by mechanical means is a water pump or agitator.