阅读说明：本技术 硅片的清洗方法及硅片的清洗设备 (Silicon wafer cleaning method and silicon wafer cleaning equipment ) 是由 陈建铭 卢健平 于 2020-05-29 设计创作，主要内容包括：本发明公开了一种硅片的清洗方法及硅片的清洗设备,包括以下步骤：步骤1：将SC1清洗溶液加热到设定温度后停止加热,其中SC1溶液为氨水、双氧水和超纯水组成混合液；步骤2：将抛光后的硅片浸入清洗溶液中,并伴随循环清洗及超声波振动,进行清洁；步骤3：当清洗时间达到设定时间后取出硅片,再将清洗溶液加热至设定温度,对下一批次硅片依照上述步骤进行清洗。本发明硅片的清洗方法采用降温清洗,达到了清洗硅片表面微粒子的功效同时相对地降低表面的粗糙度。(The invention discloses a silicon wafer cleaning method and a silicon wafer cleaning device, which comprise the following steps: step 1: heating the SC1 cleaning solution to a set temperature, and then stopping heating, wherein the SC1 solution is a mixed solution consisting of ammonia water, hydrogen peroxide and ultrapure water; step 2: immersing the polished silicon wafer into a cleaning solution, and cleaning along with circular cleaning and ultrasonic vibration; and step 3: and taking out the silicon wafer when the cleaning time reaches the set time, heating the cleaning solution to the set temperature, and cleaning the silicon wafer of the next batch according to the steps. The cleaning method of the silicon wafer adopts cooling cleaning, achieves the effect of cleaning the micro-particles on the surface of the silicon wafer and relatively reduces the roughness of the surface.)

1. A method for cleaning a silicon wafer is characterized by comprising the following steps:

step 1: heating the SC1 cleaning solution to a set temperature, and then stopping heating, wherein the SC1 cleaning solution is a mixed solution consisting of ammonia water, hydrogen peroxide and ultrapure water;

step 2: immersing the polished silicon wafer into the SC1 cleaning solution, and cleaning with circulating filtration and ultrasonic vibration;

and step 3: taking out the silicon wafer when the cleaning time reaches the set time,

and heating the cleaning solution to the set temperature, and cleaning the silicon wafers of the next batch according to the steps.

2. The method for cleaning a silicon wafer according to claim 1, wherein the set temperature is 65 ℃ to 70 ℃.

3. The method for cleaning the silicon wafer according to claim 1, wherein the set time is 4 to 7 min.

4. The method for cleaning silicon wafers according to claim 1, wherein the ratio of ammonia water in the SC1 solution: hydrogen peroxide: the volume ratio of the ultrapure water is 1:4: 50-1: 2: 25.

5. The method for cleaning the silicon wafer according to claim 1, wherein a cooling device is adopted for auxiliary cooling after the step 2, and the cooling rate is 2-4 ℃/min.

6. The method for cleaning silicon wafers according to claim 5, wherein in the step 2, the cooling device is started when the cleaning time reaches 20% to 40% of the set time.

7. The method for cleaning silicon wafers according to claim 5, wherein in the step 2, the cooling device is started when the temperature of the cleaning solution is reduced to a preset temperature, wherein the preset temperature is 58-60 ℃.

8. The method for cleaning a silicon wafer according to claim 1, further comprising the steps of:

and 4, step 4: and replenishing the cleaning solution, namely replenishing ammonia water and hydrogen peroxide according to the size and the number of the silicon wafers cleaned in the last batch, so that the volume ratio of the SC1 cleaning solution in the cleaning front accommodating tank in each batch is in a set range.

9. The method for cleaning the silicon wafer according to claim 8, wherein in the step 4, ammonia and hydrogen peroxide in the SC1 cleaning solution are respectively stored in two buffer tanks, the buffer tanks are communicated with the accommodating tank through pipelines, valves are arranged on the pipelines, and the corresponding supplement amount is controlled by controlling the opening time of the valves.

10. An apparatus for cleaning a silicon wafer, characterized in that the cleaning apparatus cleans a silicon wafer by the cleaning method according to any one of claims 1 to 9, and the cleaning apparatus comprises:

a cleaner having a holding tank for holding a cleaning solution;

the inlet of the circulating pump is communicated with the accommodating tank;

the inlet of the filter is communicated with the outlet of the circulating pump, and the outlet of the filter is communicated with the accommodating tank;

the heater is arranged on a pipeline between the accommodating tank and the filter;

an ultrasonic device disposed within the receiving tank,

and the temperature detection device is used for detecting the temperature of the cleaning solution in real time.

11. The silicon wafer cleaning apparatus according to claim 10, wherein the heater is wound or attached on an outer surface of the pipe.

12. The silicon wafer cleaning apparatus according to claim 10, further comprising:

and the cooling device is arranged at the lower end of the cleaner and is used for cooling the cleaning solution.

13. The silicon wafer cleaning apparatus according to claim 10, further comprising a control system including an information capturing system for capturing the number of silicon wafers placed in the holding tank.

Technical Field

The invention relates to the technical field of silicon wafer cleaning, in particular to a silicon wafer cleaning method and silicon wafer cleaning equipment.

Background

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a silicon wafer cleaning method, which can achieve the effect of cleaning the micro-particles on the surface of the silicon wafer and relatively reduce the roughness of the surface.

The invention also provides a silicon wafer cleaning device which cleans the silicon wafer according to the cleaning method.

The silicon wafer cleaning method provided by the embodiment of the invention comprises the following steps:

step 1: heating the SC1 cleaning solution to a set temperature, and then stopping heating, wherein the SC1 cleaning solution is a mixed solution consisting of ammonia water, hydrogen peroxide and ultrapure water;

step 2: immersing the polished silicon wafer into the SC1 cleaning solution, and cleaning with circulating filtration and ultrasonic vibration;

and step 3: taking out the silicon wafer when the cleaning time reaches the set time,

and heating the cleaning solution to the set temperature, and cleaning the silicon wafers of the next batch according to the steps.

According to the silicon wafer cleaning method provided by the embodiment of the invention, before the silicon wafer is cleaned, the cleaning solution is heated to the set temperature and then is stopped heating, then the silicon wafer is put into the cleaning solution for cleaning, the cleaning solution is in a natural cooling state, the filtering and ultrasonic vibration are carried out in the silicon wafer cleaning process, the silicon wafer is taken out when the cleaning time reaches the set time, and in the whole cleaning process of the silicon wafer, the ultrasonic cleaning is combined, so that the micro particles on the surface of the silicon wafer can be cleaned, and the surface roughness of the silicon wafer can be reduced.

According to some embodiments of the invention, the set temperature is 65 ℃ to 70 ℃.

According to some embodiments of the invention, the set time is 4-7 min.

According to some embodiments of the invention, the ratio of ammonia in the SC1 solution: hydrogen peroxide: the volume ratio of the ultrapure water is 1:4: 50-1: 2: 25.

According to some embodiments of the invention, a cooling device is adopted to assist in cooling after the step 2, and the cooling rate is 2-4 ℃/min.

In some embodiments of the invention, in the step 2, when the washing time reaches 20% to 40% of the set time, the cooling device is turned on.

In some embodiments of the present invention, in the step 2, the cooling device is turned on when the temperature of the cleaning solution is reduced to a preset temperature, wherein the preset temperature is 58 ℃ to 60 ℃.

According to some embodiments of the invention, further comprising the steps of:

and 4, step 4: and replenishing the cleaning solution, namely replenishing ammonia water and hydrogen peroxide according to the size and the number of the silicon wafers cleaned in the last batch, so that the volume ratio of the SC1 cleaning solution in the cleaning front accommodating tank in each batch is in a set range.

In some embodiments of the present invention, in step 4, the ammonia water and the hydrogen peroxide in the SC1 cleaning solution are respectively stored in two buffer tanks, the buffer tanks are communicated with the accommodating tank through a pipeline, a valve is arranged on the pipeline, and the opening time of the valve is controlled to control the corresponding replenishment amount.

According to the cleaning equipment provided by the embodiment of the invention, the cleaning equipment adopts the cleaning method to clean the silicon wafer, and the cleaning equipment comprises: a cleaner having a holding tank for holding a cleaning solution; the inlet of the circulating pump is communicated with the accommodating tank; the inlet of the filter is communicated with the outlet of the circulating pump, and the outlet of the filter is communicated with the accommodating tank; the heater is arranged on a pipeline between the accommodating tank and the filter; the ultrasonic equipment is arranged in the containing tank, and the temperature detection device is used for detecting the temperature of the cleaning solution in real time.

According to the cleaning equipment provided by the embodiment of the invention, the silicon wafer is cleaned by adopting the cleaning method, so that not only can the particles on the surface of the silicon wafer be cleaned, but also the roughness of the surface of the cleaned silicon wafer can be reduced.

In some embodiments of the invention, the heater is wrapped or conformed around the outer surface of the conduit.

In some embodiments of the invention, further comprising: and the cooling device is arranged at the lower end of the cleaner and is used for cooling the cleaning solution.

In some embodiments of the invention, the cleaning apparatus further comprises a control system comprising an information capture system for capturing the number of wafers placed in the holding tank.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a flow chart of a method for cleaning a silicon wafer according to an embodiment of the present invention;

FIG. 2 is a schematic structural view of an apparatus for cleaning a silicon wafer according to an embodiment of the present invention;

FIG. 3 is a graph of temperature and time for a silicon wafer cleaning method and a constant temperature cleaning method according to an embodiment of the present invention.

FIG. 4 is a comparative analysis of roughness for three examples and a comparative example of a silicon wafer cleaning method according to an example of the present application.

Reference numerals:

the cleaning of the apparatus 100 is carried out,

the cleaning device 1, the holding tank 11,

a circulating pump 2, a filter 3, a heater 4 and an ultrasonic device 5.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art. A method for cleaning a silicon wafer according to an embodiment of the present invention will be described with reference to fig. 1 and 2.

In the field of semiconductor technology, silicon wafer processing processes such as cutting, cleaning, polishing, etc. are all performed in a clean room, which is at a constant temperature and humidity, typically 22-25 ℃.

As shown in fig. 1, the method for cleaning a silicon wafer according to an embodiment of the present invention includes:

step 1: heating the SC1 cleaning solution to a set temperature, and then stopping heating, wherein the SC1 cleaning solution is a mixed solution consisting of ammonia water, hydrogen peroxide and ultrapure water;

step 2: putting the polished silicon wafer into an SC1 cleaning solution, and cleaning along with circular filtration and ultrasonic vibration;

and step 3: and taking out the silicon wafers of the batch when the cleaning time reaches the set time.

Principle of removing micro-particles on the surface of a silicon wafer by SC1 cleaning solution: an oxide film (about 6nm) is generated on the surface of the silicon wafer due to the oxidation action of hydrogen peroxide and is hydrophilic, and the oxide film on the surface of the silicon wafer and the silicon wafer can be slightly etched by ammonia water, so that micro-particles wrapped by the oxide film fall into a cleaning solution. In the cleaning solution, because the surface potential of the silicon wafer is negative, repulsive force exists between the silicon wafer and most of particles in the solution, particularly under the Zeta potential, the adsorption of the particles in the solution to the surface of the silicon wafer is further prevented, and meanwhile, the concentration of micro-particles in the solution is further reduced through circulating filtration, so that the aim of cleaning the silicon wafer is fulfilled.

Since the removal rate of the fine particles is related to the etching amount of the silicon wafer surface, a certain amount of etching is necessary to remove the fine particles. The key is how to control the etching degree of the silicon wafer surface after polishing (just completely etching the oxide film on the silicon wafer surface). On one hand, an oxide film wrapping the micro-particles is etched to achieve the purpose of removing the micro-particles on the surface of the silicon wafer, and the micro-etching to the surface of the silicon wafer is avoided as much as possible to influence the surface roughness of the silicon wafer.

In order to achieve the above purpose, in the present application, the temperature of the SC1 cleaning solution is first heated to a set temperature, then the heating is stopped, then the silicon wafer is put into the cleaning solution, and the cleaning process is accompanied by filtration and ultrasonic vibration, and since the cleaning process is in a clean room, the temperature of the cleaning solution is naturally lowered after the heating is stopped. Because the etching rate of the surface of the silicon wafer is in direct proportion to the reaction temperature, the temperature of the cleaning solution is continuously reduced in the cleaning process, the early-stage reaction temperature is high, the etching rate of the cleaning solution to the surface of the silicon wafer is high, and the etching rate of the cleaning solution to the surface of the silicon wafer is slow due to the low later-stage reaction temperature. The method for cleaning the silicon wafer by cooling is adopted to reduce the etching degree of the surface of the silicon wafer to a certain extent, and meanwhile, etched microparticles attached to the surface of the silicon wafer can be removed by vibration through mechanical force generated by ultrasonic waves, the microparticles in the cleaning solution and surface charges of the silicon wafer repel each other under the action of a Zeta potential, and the number of the microparticles in the cleaning solution is reduced because of the fact that the cleaning process is always accompanied with circulating filtration, so that the microparticles are effectively prevented from being adsorbed on the surface of the silicon wafer again, and the purpose of further cleaning the surface of the silicon wafer is achieved.

Specifically, in the cooling cleaning method, the SC1 cleaning solution etches the oxide film on the surface of the silicon wafer slightly, not only etches small particles slightly, but also etches the contact part between large particles and the surface slightly, and large particles and small particles on the surface can be removed easily along with the circulation filtration and the vibration of ultrasonic waves, so as to meet the effect of cleaning the micro particles. The application document adopts a cooling cleaning method, the reaction temperature is high from a set temperature (such as 65-70 ℃) to the existing constant temperature cleaning temperature (about 60 ℃), the etching rate of the surface of a silicon wafer is high, the particles on the surface of the silicon wafer are quickly removed into the cleaning solution, the removal rate can reach more than 90%, the particles in the cleaning solution are increased, in the cleaning process, the Zeta potential is utilized under the environment of PH 10-11, so that the charges on the surface of the silicon wafer and the charges on the surfaces of the particles in the cleaning solution are mutually repelled, the particles in the cleaning solution are prevented from being re-adsorbed on the surface of the silicon wafer, in order to better achieve the effect of cleaning the particles on the surface of the silicon wafer, the particles are filtered out in the cleaning process by cyclic filtration, and the quantity of the particles in the cleaning solution can be reduced only after the cyclic filtration for a certain time, in order to reduce the etching on the surface of the silicon wafer, a cooling method is adopted. Therefore, the method for cooling and cleaning is adopted, the effect of cleaning the micro-particles is met, the micro-etching rate is reduced along with cooling, the roughness of the surface of the silicon wafer is reduced to a certain extent, the quality level of the surface of the silicon wafer is improved, and the requirements of customers are better met.

And after the silicon wafers are cleaned, cleaning the next batch of silicon wafers according to the steps 1-3, namely heating the cleaning solution to a set temperature, and cleaning the polished silicon wafers of the next batch according to the steps.

Optionally, the set temperature is 65-70 ℃. If the set temperature can be 65 ℃, 66 ℃, 67 ℃, 68 ℃, 69 ℃ or 70 ℃, etc., namely the reaction temperature of the cleaning solution, the higher the reaction temperature is, the faster the etching rate is, the higher the etching rate is, the particles on the surface of the silicon wafer can be quickly etched in the initial stage of cleaning, and then the particles are removed from the surface of the silicon wafer by ultrasonic vibration, so that a key step is provided for achieving the effect of removing the particles.

Optionally, the set time is 4-7 min. For example, the set time may be 4min, 5min, 6min, or 7 min. Therefore, the silicon wafer can be ensured to have a better etching effect, the micro-particles on the surface of the silicon wafer are removed, the effect of cleaning the micro-particles is met, and the surface roughness can be reduced. The inventor finds that the set time is less than 4min through a large number of experiments, although the removal rate of the micro-particles on the surface of the silicon wafer is high, the number of the micro-particles in the cleaning solution is large in a short time, even if the zeta potential charge repulsion principle is utilized under the PH 10-11 environment, the situation that the micro-particles in the solution cannot be adsorbed on the surface of the silicon wafer again and the purpose of cleaning the surface of the silicon wafer cannot be achieved is avoided, if the set time is more than 7min, the etching degree of the surface of the silicon wafer is serious, the roughness of the surface of the silicon wafer is increased, and a large number of defects are generated in the subsequent.

Optionally, the volume ratio of the ammonia water, the hydrogen peroxide and the ultrapure water can be 1:4: 50-1: 2: 25. The SC1 cleaning solution is a mixed solution composed of ammonia water, hydrogen peroxide and ultrapure water, a layer of natural oxide film is formed on the surface of the silicon wafer under the action of the hydrogen peroxide, the natural oxide film and the silicon on the surface of the silicon wafer are corroded by the ammonia water, and the microparticles on the surface of the silicon wafer fall into the cleaning solution. By adopting the SC1 cleaning solution with the proportion, the microparticles on the surface of the silicon wafer can be removed into the solution by utilizing the corrosion action of ammonia water, so as to meet the effect of cleaning the surface of the silicon wafer.

In some embodiments of the present invention, a cooling device is used to assist in cooling after step 2, and the cooling rate is 2-4 ℃/min. Therefore, the cooling device can be used for rapidly reducing the reaction temperature of cleaning, the later-stage reaction temperature is prevented from being high, and the surface of the silicon wafer can be provided with higher corrosion scales within a certain set time, so that the reduction of the surface roughness of the cleaned silicon wafer is facilitated. The cooling device may be in an on state throughout the entire cooling process, or may be in an on state for a selected period of time.

Further, in step 2, when the cleaning time reaches 20% -40% of the set time, the cooling device is started. In some embodiments of the invention, the cooling device is turned on when the washing time reaches 20%, 30% or 40% of the set time. Before the cooling device is started, the reaction temperature is high, small particle parts and large particles in the silicon wafer oxidation layer can be quickly micro-etched with parts in contact with the surface of the silicon wafer, micro-particles on the surface of the silicon wafer can be timely removed under the action of mechanical force of ultrasonic waves, and the removal rate can reach over 90%. In order to reduce the further micro-etching on the surface of the silicon wafer oxidation layer, a cooling device is started, the reaction temperature is reduced, the speed of etching the surface of the silicon wafer is reduced, and the surface roughness of the silicon wafer is greatly reduced. In addition, when the cooling device is started, more than 90% of the particles on the surface of the silicon wafer are removed into the cleaning solution, so that more particles are in the cleaning solution, the quantity of the particles in the cleaning solution is greatly reduced through continuous circulating filtration, the particles in the solution are fundamentally prevented from being adsorbed on the surface of the silicon wafer, the effect of removing the particles on the surface of the silicon wafer is better achieved under the action of zeta potential, and the quality of the surface of the silicon wafer is improved.

Of course, the present invention is not limited thereto, and in step 2, the cooling device may be turned on when the temperature of the cleaning solution is reduced to a preset temperature, wherein the preset temperature is 58 ℃ to 60 ℃. The inventor finds through a large number of experiments that when the temperature of the cleaning solution is reduced from the set temperature (65-70 ℃) to 58 ℃ (or 59 ℃ and 60 ℃), the reaction temperature is high, the particles in the silicon wafer oxidation layer can be completely etched more quickly, the particles on the surface of the silicon wafer can be removed timely along with the vibration effect of ultrasonic waves, and the removal rate can reach more than 95%. Starting a cooling device later, continuously and circularly filtering to reduce the number of the micro-particles in the cleaning solution in time, and simultaneously preventing the micro-particles in the solution from being adsorbed on the surface of the silicon wafer again under the action of a Zeta potential; the reaction temperature is reduced, so that the etching rate is also reduced, and as a result, the surface roughness of the silicon wafer is greatly reduced, and the surface quality of the silicon wafer is improved.

In some embodiments of the invention, after the silicon wafers are removed, the ultrasonic cleaning mode is turned off (ultrasonic vibration is stopped) until the next batch of silicon wafers is placed in the cleaning solution and then the ultrasonic cleaning mode is turned on (ultrasonic vibration is started). It can be understood that after the last batch of silicon wafers are taken out after cleaning, the ultrasonic cleaning mode is turned off, the cleaning solution is heated, and the ultrasonic cleaning mode is turned on again after the cleaning solution is heated to the set temperature and is put into the silicon wafers, so that the working time of the ultrasonic cleaning device 5 can be reduced, and the service life of the ultrasonic cleaning device 100 can be prolonged.

Of course, the invention is not limited thereto, and in other embodiments of the invention, the ultrasonic cleaning mode is turned on until all the silicon wafers are cleaned and then turned off. It can be understood that the ultrasonic cleaning mode is started after the cleaning solution is put into the first batch of silicon wafers, the ultrasonic cleaning mode is not closed after the first batch of silicon wafers are taken out after the cleaning is finished, the cleaning solution is heated to the set temperature for cleaning the next batch of silicon wafers, and the ultrasonic cleaning mode is closed until all the silicon wafers are cleaned, so that the operation of the silicon wafer cleaning process can be simplified.

In some embodiments of the invention, the cleaning method further comprises:

and 4, step 4: and replenishing the cleaning solution, namely replenishing ammonia water and hydrogen peroxide according to the size and the number of the silicon wafers cleaned in the last batch, so that the volume ratio of the SC1 cleaning solution in the cleaning front accommodating tank in each batch is in a set range. In the silicon wafer cleaning process, the concentration of various chemicals in the cleaning solution is reduced along with the consumption of the etching reaction, so that the cleaning effect is reduced, and in order to ensure the cleaning effect of the silicon wafer, after a batch of silicon wafers are cleaned, ammonia water and hydrogen peroxide are supplemented into the cleaning solution, so that the volume ratio of the SC1 cleaning solution in the accommodating tank before each batch of cleaning is within a set range.

Specifically, ammonia water and hydrogen peroxide are supplemented according to the size and the number of the silicon wafers in the previous batch. The greater the number of wafers, the greater the amount of chemicals consumed, the fewer the number of wafers, the less the amount of chemicals consumed. The chemical consumption amount of the silicon wafers with the same size is the same and fixed, the chemical consumption amount of the silicon wafers with the same size is the product of the chemical consumption amount of a single silicon wafer and the number of the silicon wafers, the chemical consumption amount of the single silicon wafer can be calculated according to the thickness variation before and after actual silicon wafer etching or the concentration of the chemical in a cleaning solution is judged according to the pH value at the initial process debugging stage, the chemical consumption amount of the single silicon wafer is calculated through the two methods, and the replenishment amount of the chemical to be replenished is obtained, wherein the consumption amount is equal to the replenishment amount. The two calculation methods involved are prior art and are not described in detail herein.

For example, two silicon wafers can be placed in the accommodating tank 11, 25 silicon wafers can be placed in each box, at the initial stage of process debugging, 50, 40, 25, 10 and 5 silicon wafers can be placed in 8 inches or 12 inches, the amount of liquid to be replenished is calculated respectively, a curve of the amount of liquid replenishing quantity and the number of silicon wafers is established, and the amount of liquid to be replenished when different numbers of silicon wafers are placed can be estimated according to the curve.

After cleaning is finished each time, according to the number and the size of the silicon wafers cleaned at this time, the amount of the liquid supplementing liquid to be added is estimated according to the curve graphs of the liquid supplementing liquid and the number of the silicon wafers.

Further, in step 4, ammonia water and hydrogen peroxide in the SC1 cleaning solution are respectively stored in two buffer tanks, the buffer tanks are communicated with the holding tank 11 for holding the cleaning solution through pipelines, valves are arranged on the pipelines, and when the ammonia water and the hydrogen peroxide are replenished, the corresponding replenishment amount is controlled by controlling the opening time of the valves. The quantity of chemicals flowing out when the valve is opened at the same time is the same, the time for opening the valve is in direct proportion to the supplement quantity of the chemicals, the quantity of the supplemented chemicals is controlled by controlling the time for opening the valve, and the method is simpler and easy to operate and can ensure the accuracy of the quantity of the supplemented chemicals. Further, the buffer tank is located above the accommodating tank 11. After the valve is opened, the chemicals in the buffer tank can flow out to holding tank 11 in the pipeline under the effect of gravity, can omit to set up the pump on the pipeline, is favorable to saving the cost.

In some embodiments of the present invention, two methods are generally used to determine the size and number of wafers that were cleaned in the previous batch. The silicon wafer cleaning equipment comprises a control system, wherein the control system is provided with an input interface, the number of the silicon wafers needs to be input before the silicon wafers are cleaned, the number of the silicon wafers can be simply and visually acquired, and the amount of the liquid supplement required to be supplemented at this time is acquired according to a curve graph of the amount of the liquid supplement and the number of the silicon wafers. Or the control system comprises an information capturing system which can automatically capture the number of the silicon wafers in the accommodating tank 11 of the cleaning equipment 100, thereby simplifying manual input and improving production efficiency.

Referring to fig. 2, a cleaning apparatus 100 for silicon wafers according to an embodiment of the present invention will be described, the cleaning apparatus 100 being capable of cleaning silicon wafers using the above-described cleaning method.

As shown in fig. 2, the cleaning apparatus 100 according to the embodiment of the present invention includes a cleaner 1, a circulation pump 2, a filter 3, a heater 4, an ultrasonic device 5, and a temperature detection device.

Specifically, the cleaning apparatus 1 has a holding tank 11, the holding tank 11 is used for holding a cleaning solution, and a silicon wafer is placed in the holding tank 11 for cleaning. The import and the holding tank 11 intercommunication of circulating pump 2, the import of filter 3 and circulating pump 2's export intercommunication, filter 3's export and holding tank 11 intercommunication, circulating pump 2 can circulate the cleaning solution in the holding tank 11 back to holding tank 11 again after filter 3 in, and at the circulating in-process, filter 3 filters the particulate in the cleaning solution, reduces the quantity of particulate in the cleaning solution.

The heater 4 is arranged on the pipeline between the holding tank 11 and the filter 3, the heater 4 is turned on before the silicon wafer is cleaned, and the heater 4 is turned off after the silicon wafer is heated to a set temperature. Of course, the present invention is not limited thereto as long as the cleaning solution can be heated to the set temperature, and the heater 4 may be provided between the circulation pump 2 and the holding tank 11 or between the circulation pump 2 and the filter 3.

Alternatively, as shown in fig. 2, an ultrasonic device 5 is provided in the housing tank 11 to facilitate cleaning of the silicon wafer.

The temperature detection device is used for detecting the temperature of the cleaning solution in real time. The temperature detection device can detect the temperature of the cleaning solution, so that when the temperature reaches a set temperature, such as 65-70 ℃, the heater 4 stops heating, and the problem that the surface quality of the silicon wafer is influenced due to overhigh temperature of the cleaning solution is avoided.

It should be noted that the circulation pump 2 is kept in an on state all the time during the cleaning process to ensure that the particles in the cleaning solution can be removed in time, so as to satisfy the effect of cleaning the particles.

As shown in fig. 3, a relationship diagram of temperature and time between the constant temperature cleaning method and the cleaning method of the silicon wafer of the present application is shown, and in each cleaning cycle, the cleaning method of the silicon wafer of the present application, i.e., the natural cooling, is adopted, wherein the set temperature is 65 to 70 ℃, and the temperature in the constant temperature cleaning method is set to 60 ℃.

A large number of tests show that the cleaning method of the silicon wafer adopts cooling cleaning, when the temperature of the cleaning solution is reduced to 60 ℃, the removal rate of the micro-particles on the surface of the silicon wafer can reach more than 95%, and the micro-etching of the surface of the silicon wafer is basically completed. According to the cleaning method, after the cleaning temperature is lower than 60 ℃, on one hand, the number of the particles in the solution is timely reduced through circulating filtration, so that the effect of cleaning the particles on the surface of the silicon wafer is achieved, on the other hand, the temperature of the cleaning solution is continuously reduced, the etching rate is reduced, the roughness of the surface of the silicon wafer is relatively reduced, the quality level of the surface of the silicon wafer is improved, and the requirements of customers are better met.

Through multiple tests and result analysis of the inventor, the cleaning method for the silicon wafer can reduce the roughness of the surface of the silicon wafer by 30-40% compared with a constant-temperature cleaning method, reduce the micro-etching degree of the silicon wafer, and fundamentally improve the yield of subsequent processes.

According to the cleaning equipment 100 for cleaning the silicon wafer, disclosed by the embodiment of the invention, the silicon wafer is cleaned by using the cleaning method, so that the cleaning effect on the silicon wafer can be ensured, and the roughness of the surface of the cleaned silicon wafer can be reduced.

In some embodiments of the present invention, the cleaning apparatus 100 further comprises a cooling device disposed at a lower end of the cleaner for cooling the cleaning solution. Wherein cooling device can be the refrigerator, and the refrigerator can use in whole cooling process, also can use in the cooling later stage. When the refrigerator is used in the later stage of cooling of the cleaning solution, the temperature is relatively high in the initial cleaning stage, the reaction rate is high, small particles on the surface of a silicon wafer and large particles in contact with the small particles can be quickly etched in a micro mode, and micro particles on the surface can be removed in time along with ultrasonic vibration; at the later stage of washing, reduce cleaning solution's temperature through the refrigerator fast, reduced reaction rate, avoid cleaning solution to the further sculpture on silicon chip surface to the quality on assurance silicon chip surface that can be better improves the surface quality of silicon chip.

The following describes a method for cleaning a silicon wafer according to the present application with a specific example.