CN102345968B - Device and method for drying microemulsion based on supercritical carbon dioxide - Google Patents

Abstract

The invention discloses a drying device and method based on supercritical carbon dioxide microemulsion, which uses liquid carbon dioxide to replace the water-based cleaning solution, then adds a surfactant and heats the carbon dioxide to make it reach a supercritical state. structure etc. to dry. Because the method avoids the generation of gas-liquid interface and prevents the effect of surface tension, it can clean and dry high aspect ratio or porous structures without damage. Compared with the current supercritical carbon dioxide drying method, this method does not need to use an organic solution, so it will not cause damage to the photoresist, etc.; and the drying time is greatly reduced, which can effectively prevent the problem of pattern collapse. The method meets the requirements of reducing the consumption of organic solution and saving energy in the international semiconductor technology blueprint, and is easily compatible with the current IC process.

Description

Device and method based on supercritical carbon dioxide microemulsion drying

technical field

The invention relates to the technical field of semiconductor cleaning and drying, in particular to a device and method for drying microemulsions based on supercritical carbon dioxide (SCCO ₂ ).

Background technique

In the manufacturing process of microelectronic devices, with the further reduction of feature size and the further increase of structure complexity, the collapse of device structure has become an increasingly serious problem. When the devices cleaned with water as the main solvent are dried, the weaker mechanical structures such as micro-electro-mechanical components and photoresist patterns with high aspect ratios will be damaged.

As an environmentally friendly and cheap solvent, carbon dioxide has a supercritical state with close to zero surface tension and high diffusivity, which is very suitable for semiconductor cleaning processes, so the 2006 International Semiconductor Technology Blueprint (ITRS) will supercritical Fluids are regarded as new green solvents that can solve cleaning and drying in semiconductor and MEMS technology. Although the method of replacing the organic solution with liquid carbon dioxide and then entering the supercritical state for drying can effectively solve the current problem of structure collapse. However, in order to avoid a certain amount of organic solution or water still remaining in the device structure, it is often necessary to perform repeated pulse replacement, which is not only time-consuming, but also consumes a large amount of carbon dioxide. Add some special surfactants to carbon dioxide. When carbon dioxide meets water, microemulsion droplets can be formed under certain conditions, which will greatly increase the solubility of water in carbon dioxide. The microemulsion system composed of supercritical carbon dioxide and surfactant can be dried quickly and efficiently by replacing deionized water with liquid carbon dioxide.

Therefore, the proposal based on supercritical carbon dioxide microemulsion system will be an effective way to solve this problem.

Contents of the invention

(1) Technical problems to be solved

In view of this, the main purpose of the present invention is to provide a device and method based on supercritical carbon dioxide microemulsion drying.

(2) Technical solution

To achieve the above object, the invention provides a device based on supercritical carbon dioxide microemulsion drying, comprising:

The liquid storage tank 1 that is equipped with surfactant and the gas storage tank 2 that provides high-purity carbon dioxide are connected to the solenoid valve 5 through the second booster pump 3 and the first booster pump 4 respectively, and the other end of the solenoid valve 5 connected to the inlet of the reaction chamber 6;

One outlet pipeline of the reaction chamber 6 is connected to the observation window 10 through the first manual valve 9, and the other outlet pipeline is connected to the second heat exchanger 18 through the first expansion valve 19;

The outlet of the observation window 10 is connected to the first separator 13, and a second expansion valve 11 and the first heat exchanger 12 are connected on the connection pipeline between the observation window 10 and the first separator 13; the outlet of the first separator 13 Connected to the first filtration and purification device 15, the first filtration and purification device 15 is connected to the reaction chamber 6 through the third booster pump 23 and the fourth heat exchanger 24;

The outlet of the second heat exchanger 18 is connected to the third separator 17, and the third separator 17 passes through the third heat exchanger 21, the second separator 20, the cooling device 22, the third booster pump 23 and the fourth heat exchanger in sequence. The exchanger 24 is connected to the reaction chamber 6;

An outlet of the second separator 20 is connected to the surfactant storage tank 1 through a fourth manual valve 25 and a second filter purification device 26 .

In the above solution, the reaction chamber 6 is fixed with a reversible and rotatable tray 8 inside, and a cold cycle 29 system, a heating system 30 , a temperature measuring device 27 and a pressure measuring device 28 are installed outside it.

In the above scheme, the first end of the third separator 17 is connected to the outlet of the second heat exchanger 18, the second end is connected to the second separator 20 through the third heat exchanger 21, and the third end is connected with The third manual valve 16.

In the above scheme, the device has a carbon dioxide recycling system, including:

The first manual valve 9 that is connected to reaction chamber 6 bottoms, its other end is connected with observation window 10, and the outlet of observation window 10 is connected with second expansion valve 11 and first heat exchanger 12, from first heat exchanger 12 The carbon dioxide that comes out flows in the first separator 13, then flows in the reaction chamber 6 through the third booster pump 23 and the fourth heat exchanger 24 through the first filter purification device 15;

The first expansion valve 19 that is connected to the reaction chamber 6 bottom, its other end is connected with the second heat exchanger 18, the carbon dioxide that comes out from the second heat exchanger 18 flows in the 3rd separator 17, from the 3rd separator The carbon dioxide out of 17 flows into the second separator 20 through the third heat exchanger 21, and the other end of the second separator 20 is connected to the cooling device 22, and the carbon dioxide out of the cooling device 22 passes through the third booster pump 23 and the fourth heat exchanger 24 flow into the reaction chamber 6 .

In the above scheme, the device has a surfactant recycling system, comprising:

The first expansion valve 19 connected to the bottom of the reaction chamber 6, the other end of which is connected to the second heat exchanger 18, the second heat exchanger 18 is connected to the third separator 17, and the top outlet of the third separator 17 passes through the first Three heat exchangers 21 are connected with the inlet of the second separator 20, and the surfactant flows back into the surfactant storage tank 1 through the fourth manual valve 25 and the second filter purification device 26 from the outlet of the second separator 20 .

In order to achieve the above object, the present invention also provides a drying method based on supercritical carbon dioxide microemulsion, the method is to utilize liquid carbon dioxide to replace deionized water, then utilize SCCO based on _{Microemulsion} to dry the structure pattern, then pass through Pure carbon dioxide purge.

In the above solution, the water is deionized water, and the carbon dioxide source is used with a purity of more than 5N, and the choice of surfactant will not cause damage to the structural pattern.

(3) Beneficial effects

As can be seen from the foregoing technical solutions, the present invention has the following beneficial effects:

1. This drying device and method based on supercritical carbon dioxide microemulsion provided by the present invention, supercritical carbon dioxide has unique properties such as very low viscosity coefficient, high diffusivity and negligible surface tension, and is suitable for finer structures. It will not be damaged by surface tension and capillary pull, so it can effectively solve the problem of structure collapse during drying and provide clean and dry devices. Therefore, using supercritical carbon dioxide as a new green cleaning and drying solvent for next-generation semiconductors not only reduces the use of organic solvents, protects the environment, and reduces energy consumption, but also conforms to the development trend of ITRS. Directly replace the aqueous solution with liquid carbon dioxide, and dry in a supercritical carbon dioxide microemulsion environment, avoiding the use of a large amount of organic solution and carbon dioxide, shortening the cleaning time and improving efficiency. Therefore, whether in terms of environmental protection or economic benefits, the supercritical carbon dioxide microemulsion system has good development and application prospects, and is expected to be used in microelectronics processing production lines.

2. The drying device and method based on the supercritical carbon dioxide microemulsion provided by the present invention mainly utilizes liquid carbon dioxide to replace the water-based cleaning solution, then adds a surfactant and heats the carbon dioxide to make it reach a supercritical state for photoresist or MEMS Drying of the microstructure etc. in the Because the method avoids the generation of gas-liquid interface and prevents the effect of surface tension, it can clean and dry high aspect ratio or porous structures without damage. Compared with the current supercritical carbon dioxide drying method, this method does not need to use an organic solution, so it will not cause damage to the photoresist, etc.; and the drying time is greatly reduced, which can effectively prevent the problem of pattern collapse. The method meets the requirements of reducing the consumption of organic solution and saving energy in the international semiconductor technology blueprint, and is easily compatible with the current IC process.

Description of drawings

Fig. 1 is the schematic diagram of the device based on supercritical carbon dioxide microemulsion drying provided by the present invention;

Fig. 2 is the schematic diagram of liquid carbon dioxide replacement and SCCO _{microemulsion} drying process among the present invention;

Among them, 1 is the surfactant storage tank, 2 is the carbon dioxide gas storage tank, 3 is the second booster pump, 4 is the first booster pump, 5 is the solenoid valve, 6 is the reaction chamber, 7 is the sample to be dried, 8 is a reversible and rotatable tray, 9 is the first manual valve, 10 is the observation window, 11 is the second expansion valve, 12 is the first heat exchanger, 13 is the first separator, 14 is the second manual valve , 15 is the first filter purification device, 16 is the third manual valve, 17 is the third separator, 18 is the second heat exchanger, 19 is the first expansion valve, 20 is the second separator, 21 is the third heat exchanger Exchanger, 22 is a cooling device, 23 is a third booster pump, 24 is a fourth heat exchanger, 25 is a fourth manual valve, 26 is a second filtration and purification device; 27 is a temperature sensor; 28 is a pressure sensor; 29 Is a cold cycle system; 30 is a heating system.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be described in further detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

As shown in Fig. 1, Fig. 1 is the schematic diagram of the device based on supercritical carbon dioxide microemulsion drying provided by the present invention, and this device comprises:

The liquid storage tank 1 that is equipped with surfactant and the gas storage tank 2 that provides high-purity carbon dioxide are connected to the solenoid valve 5 through the second booster pump 3 and the first booster pump 4 respectively, and the other end of the solenoid valve 5 connected to the inlet of the reaction chamber 6;

One outlet pipeline of the reaction chamber 6 is connected to the observation window 10 through the first manual valve 9, and the other outlet pipeline is connected to the second heat exchanger 18 through the first expansion valve 19;

The outlet of the observation window 10 is connected to the first separator 13, and a second expansion valve 11 and the first heat exchanger 12 are connected on the connection pipeline between the observation window 10 and the first separator 13; the outlet of the first separator 13 Connected to the first filtration and purification device 15, the first filtration and purification device 15 is connected to the reaction chamber 6 through the third booster pump 23 and the fourth heat exchanger 24;

The outlet of the second heat exchanger 18 is connected to the third separator 17, and the third separator 17 passes through the third heat exchanger 21, the second separator 20, the cooling device 22, the third booster pump 23 and the fourth heat exchanger in sequence. The exchanger 24 is connected to the reaction chamber 6;

An outlet of the second separator 20 is connected to the surfactant storage tank 1 through a fourth manual valve 25 and a second filter purification device 26 .

Wherein, the inside of the reaction chamber 6 is fixed with a reversible and rotatable tray 8 , and its outside is equipped with a cooling cycle 29 system, a heating system 30 , a temperature measuring device 27 and a pressure measuring device 28 . The third separator 17, its first end is connected with the outlet of the second heat exchanger 18, the second end is connected with the second separator 20 through the third heat exchanger 21, and the third end is connected with the third manual valve 16.

The device based on supercritical carbon dioxide microemulsion drying provided by the present invention has a carbon dioxide recycling system, including: the first manual valve 9 connected to the bottom of the reaction chamber 6, the other end of which is connected to the observation window 10, and the observation window 10 The outlet is connected with the second expansion valve 11 and the first heat exchanger 12, and the carbon dioxide from the first heat exchanger 12 flows into the first separator 13, and then passes through the first filtration and purification device 15 and passes through the third booster pump 23 and the fourth heat exchanger 24 flow into the reaction chamber 6; connected to the first expansion valve 19 at the bottom of the reaction chamber 6, the other end of which is connected to the second heat exchanger 18, from the second heat exchanger 18 Carbon dioxide flows in the third separator 17, and the carbon dioxide that comes out from the third separator 17 flows in the second separator 20 through the third heat exchanger 21 again, and the other end of the second separator 20 is connected with cooling device 22, from The carbon dioxide from the cooling device 22 flows into the reaction chamber 6 through the third booster pump 23 and the fourth heat exchanger 24 .

The device based on supercritical carbon dioxide microemulsion drying provided by the present invention also has a surfactant recycling system, including: the first expansion valve 19 connected to the bottom of the reaction chamber 6, and its other end connected to the second heat exchanger 18, the second heat exchanger 18 is connected with the third separator 17, the top outlet of the third separator 17 is connected with the inlet of the second separator 20 through the third heat exchanger 21, and the surfactant is discharged from the second separator The outlet of 20 flows back into the surfactant storage tank 1 through the fourth manual valve 25 and the second filtration and purification device 26 .

Referring again to Fig. 1, the connection relation of each part in the device based on supercritical carbon dioxide microemulsion drying provided by the present invention is: the outlet of surfactant storage tank 1 is connected to an end of solenoid valve 5 by the second booster pump 3; The outlet of the storage tank 2 is connected to one end of the solenoid valve 5 through the first booster pump 4; the other end of the solenoid valve 5 is connected to the inlet end of the reaction chamber 6; the dried sample piece 7 is fixed on a rotatable and reversible tray 8; the outlet of the reaction chamber 6 is located at the bottom, and is connected with the observation window 10 through the first manual valve 9; the outlet of the observation window 10 is connected to the second expansion valve 11, and then through the first heat exchanger 12 and the first separator The inlets of 13 are connected, and the bottom outlet is connected with the second manual valve 14; the top outlet of the first separator 13 is connected with the first filter purification device 15, and then connected with the inlet of the third booster pump 23; the third booster The outlet of the pump 23 is connected to the reaction chamber 6 via the fourth heat exchanger 24; the other outlet of the reaction chamber 6 communicates with the inlet of the third separator 17 through the first expansion valve 19 and the second heat exchanger 18; The waste liquid in the three separators 17 is discharged by the 3rd manual valve 16, and its top outlet is connected to the inlet of the second separator 20 through the 3rd heat exchanger 21; Three booster pumps 23 are connected, then are connected with electromagnetic valve 5 through the 4th heat exchanger 24; Storage tank 1 communicates; Temperate zone sensor 27 is positioned at the top of reaction chamber 6, and pressure sensor 28 is positioned at the top of reaction chamber 6; Cold cycle system 29 is wound on the outer wall of reaction chamber 6, and heating system 30 is fixed on the top of reaction chamber 6 external.

In conjunction with Fig. 1, the effect of each part in the device based on supercritical carbon dioxide microemulsion drying that the present invention provides is respectively: the first, the second and the 3rd booster pump are used for pumping the reactant into the chamber and adding to the chamber pressure; the temperate sensor 27 is used for real-time measurement and display of the temperature in the reaction chamber 6; the pressure sensor 28 is used for real-time measurement and display of the pressure in the reaction chamber 6; the tray 8 is designed to be rotatable and overturned to make the dried sample Most of the water in 7 is separated from the silicon wafer under the action of mechanical force; the cold circulation system 29 is used to cool the reaction chamber 6 so as to maintain the carbon dioxide entering in a liquid state; the heating system 30 is used to heat the reaction chamber 6 Thereby make carbon dioxide reach supercritical state; The effect of observation window 10 is to be used for observing whether replacement is complete; The effect of expansion valve is to make high-pressure medium temperature material become low-temperature low-pressure state; The first, second, third and fourth heat exchangers Further enhance the gas-liquid separation; the first, second and third separators realize gas-liquid separation and collect liquid substances; the cooling device 22 is used to refrigerate gaseous carbon dioxide to make it into a liquid state; the first and second filter purification devices are used To filter and purify the substances that need to be recycled.

As shown in Figure 2, Figure 2 is a schematic diagram of liquid carbon dioxide replacement and _SCCO2 microemulsion drying process in the present invention, the drying process based on _SCCO2 microemulsion system is: put the corroded structure or figure into the reaction chamber on a silicon wafer chuck and submerged in deionized water to prevent the occurrence of an air-liquid interface. Then the reaction chamber is sealed and refrigerated so that the temperature reaches 5°C and the pressure is maintained at 4MPa. This process can be measured and displayed in real time through temperature and pressure sensors; at this time, the carbon dioxide entering the chamber is a liquid with a density of 0.893g/ cm ³ , less than the density of water, so liquid carbon dioxide is pumped into the chamber from the upper part of the reaction chamber. Because the solubility of water in pure liquid carbon dioxide is very small, it is easy to be replaced by liquid carbon dioxide; The position of the interface to analyze whether the replacement is sufficient; the mixed liquid in the window is discharged into the first separator through the expansion valve and the heat exchanger; the gaseous carbon dioxide in the first separator is filtered and purified by the filter purifier, and then the The pump pressurizes and injects into the chamber for recycling; the waste liquid in the first separator can be discharged through the second manual valve; Press the pump, add the surfactant, then close the cold circulation system, turn on the heating system, and heat the reaction chamber; when the carbon dioxide reaches the supercritical state, turn the tray containing the silicon wafer upside down and rotate it at the same time, so that the silicon wafer is covered Most of the water on the surface leaves the surface of the silicon wafer under the action of centrifugal force, and a small part of the water will form microemulsion droplets in SCCO ₂ due to the action of the surfactant, and dry the silicon wafer; after drying for a period of time, the gaseous pure Carbon dioxide, the SCCO ₂ microemulsion in the chamber is discharged into the third separator and the second separator through the expansion valve; the waste liquid in the third separator can be discharged through the control of the third manual valve; from the third separator The gaseous carbon dioxide separated from the second separator becomes liquid after cooling by the cooler, and finally injected into the reaction chamber by the booster pump for recycling; the surfactant in the second separator can be purified and filtered by the filtration purification device recycle. After drying, the chamber is depressurized to normal pressure. During the decompression process, it is necessary to ensure that the temperature of the chamber is always greater than the critical temperature; then the final sample can be taken out for subsequent analysis. Finally, the waste liquid such as water in the separator is discharged.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (6)

1. the device based on supercritical carbon dioxide microemulsion drying is characterized in that, comprising:

The fluid reservoir (1) of surfactant is housed and the air accumulator (2) of high-purity carbon dioxide is provided, the two is connected in magnetic valve (5) by second booster pump (3) and first booster pump (4) respectively, and the other end of magnetic valve (5) is connected in the inlet of reaction chamber (6);

Be connected in observation window (10) by first hand-operated valve (9) on the export pipeline of reaction chamber (6), be connected in second heat exchanger (18) by first expansion valve (19) on another export pipeline; Reaction chamber (6) internal fixation has turning and rotary-tray (8), and its outside is equipped with cold circulation (29) system, heating system (30), temperature measuring equipment (27) and device for pressure measurement (28);

The outlet of observation window (10) is connected in first separator (13), is connected to one second expansion valve (11) and first heat exchanger (12) on the connecting line of observation window (10) and first separator (13); The outlet of first separator (13) is connected in first and filters purification devices (15), and first filters purification devices (15) is connected in reaction chamber (6) by the 3rd booster pump (23) and the 4th heat exchanger (24);

The outlet of second heat exchanger (18) is connected in the 3rd separator (17), and the 3rd separator (17) is connected in reaction chamber (6) by the 3rd heat exchanger (21), second separator (20), cooling device (22), the 3rd booster pump (23) and the 4th heat exchanger (24) successively;

An outlet of second separator (20) is filtered purification devices (26) by the 4th hand-operated valve (25) and second and is connected in surfactant storage tank (1).

2. the device based on supercritical carbon dioxide microemulsion drying according to claim 1, it is characterized in that, described the 3rd separator (17), its first end is connected with the outlet of second heat exchanger (18), second end is connected with second separator (20) by the 3rd heat exchanger (21), and the 3rd termination has the 3rd hand-operated valve (16).

3. the device based on supercritical carbon dioxide microemulsion drying according to claim 1 is characterized in that, this device has a carbon dioxide and recycles system, comprising:

Be connected to first hand-operated valve (9) of reaction chamber (6) bottom, its other end is connected in observation window (10), the outlet of observation window (10) is connected with second expansion valve (11) and first heat exchanger (12), the carbon dioxide that comes out from first heat exchanger (12) flows in first separator (13), filters purification devices (15) through first again and flows in the reaction chamber (6) by the 3rd booster pump (23) and the 4th heat exchanger (24);

Be connected to first expansion valve (19) of reaction chamber (6) bottom, its other end is connected in second heat exchanger (18), the carbon dioxide that comes out from second heat exchanger (18) flows in the 3rd separator (17), the carbon dioxide that comes out from the 3rd separator (17) flows in second separator (20) through the 3rd heat exchanger (21) again, the other end of second separator (20) is connected in cooling device (22), and the carbon dioxide that comes out from cooling device (22) flows in the reaction chamber (6) by the 3rd booster pump (23) and the 4th heat exchanger (24).

4. the device based on supercritical carbon dioxide microemulsion drying according to claim 1 is characterized in that, this device has a surfactant and recycles system, comprising:

Be connected to first expansion valve (19) of reaction chamber (6) bottom, its other end is connected in second heat exchanger (18), second heat exchanger (18) is connected with the 3rd separator (17), the top exit of the 3rd separator (17) is connected through the 3rd heat exchanger (21) and the inlet of second separator (20), and surfactant filters purification devices (26) through the 4th hand-operated valve (25) and second again from the outlet of second separator (20) and flows back to the surfactant storage tank (1).

5. the drying means based on the supercritical carbon dioxide microemulsion is applied to the described device of claim 1, it is characterized in that, this method is to utilize liquid carbon dioxide displacement deionized water, then utilizes based on SCCO ₂Microemulsion structure graph is carried out drying, feed the pure carbon dioxide purge then.

6. the drying means based on the supercritical carbon dioxide microemulsion according to claim 5 is characterized in that, described water is deionized water, and uses carbon dioxide source purity to reach more than the 5N, and the selection of surfactant can not cause damage to structure graph.

Images