1, trough cleaning equipment: wet chemical cleaning system can be both trough and rotary. The general equipment mainly consists of a set of wet chemical cleaning tanks and the corresponding water tank, and may also be equipped with a spin-drying device. The wafers are placed in a special washing basket and placed in a chemical tank for a specified period of time, then removed and washed in the corresponding water tank.
The choice of materials is crucial to the design of cleaning equipment. Use according to the concentration of chemical liquid, pH, temperature and other conditions to choose the corresponding tank material. Generally speaking, there are NPP, PVDF, PTFE, quartz glass, stainless steel and so on. For example: PVDF, PTFE, quartz glass is generally used in need of heating strong acid and strong alkali cleaning, quartz glass can not be used in HF cleaning, NPP is generally used in the room temperature of weak acid and weak alkali cleaning, stainless steel is generally used in organic liquid cleaning. And normal temperature chemical tank, generally for NPP materials.
The solution in the tank can be heated to 180℃ or higher, which is generally composed of quartz inner tank, insulation layer, plastic (PP) outer tank. The quartz tank can be heated by pasting a heating film or directly coating a heating material on the quartz glass. Quartz tank needs to install temperature and liquid level sensors to achieve accurate temperature control and liquid level detection in the tank, to prevent the heater dry burning caused by the low liquid level in the tank. In addition, PVDF(PTFE) heating tank is also more commonly used, this kind of heating tank is often used in HF solution cleaning. Due to the limitation of the tank material, this kind of heating tank can only be used for diving heating. The diving heater generally has two kinds of coil type and plate type, and the heater is covered with PFA tube.
In addition, with the continuous improvement of cleaning requirements, the tank can also be equipped with circulation, filtration and other functions. The circulation function is mainly for the purpose of more uniform mixing environment of medicine and liquid, and sometimes it is added into the circulating pump to make the liquid circulate in the tank. The filtering function is that some impurities are produced in the cleaning process of the liquid, which will sometimes affect the cleaning effect. At this time, the addition of the filtering function is more conducive to filtering impurities and improving the cleaning effect
2, ultrasonic cleaning
The main purpose of ultrasonic cleaning is to remove the contaminant film on the surface of the wafer but not the particles. During the cleaning process, the wafer is immersed in the cleaning solution and the particles on the front and back of the wafer are effectively removed by using ultra-high frequency acoustic energy. The main principle of ultrasonic cleaning is to use ultrasonic cavitation effect, radiation pressure and sound flow, first place the silicon wafer in the cleaning liquid in the tank, use the ultrasonic vibrator at the bottom of the tank to work, transfer energy to the liquid, and through the liquid in the form of acoustic wave front. When the vibration is strong, the liquid will be torn apart, resulting in a lot of bubbles, called cavitation bubbles. These bubbles are the key to ultrasonic cleaning, they store the cleaning energy, once these bubbles hit the surface of the silicon wafer, they will burst, released a huge energy can clean the surface of the silicon wafer. The effect of ultrasonic cleaning can be increased by adding appropriate surfactant in the cleaning solution.
Ultrasonic cleaning has many advantages: fast cleaning speed; The cleaning effect is better; Can clean a variety of complex shapes of silicon wafer surface; Easy to achieve remote control and automation. Its defects have the following aspects: the cleaning effect of ultrasonic on pollutants with different particle sizes is different, the larger the particle size, the better the cleaning effect; However, when the particle size changes, the cleaning effect is not good. For particles with a particle size of only a few microns, it is necessary to use megaconic cleaning to remove them. When the cavity bubble blasting, the huge energy will cause certain damage to the silicon wafer.
3, rotating spray cleaning
Rotary spray cleaning is a variation of immersion cleaning. The system generally includes automatic liquid distribution system, cleaning chamber, waste liquid recovery system. Spray cleaning in a sealed working chamber to complete the chemical cleaning, deionized water washing, rotating dry and other processes, reducing the impact of human operation factors in each step of the cleaning process. Due to the rotation and spraying effect in the spray cleaning, the solution on the surface of the silicon wafer is more uniform. At the same time, the solution on the surface of the silicon wafer is always fresh. In this way, the cleaning and corrosion effect of the silicon wafer can be accurately controlled through the process time setting, and good consistency can be achieved. The sealed working chamber can isolate the volatilization of chemical liquid, reduce the loss of solution and the harm of solution vapor to human body and environment. Each system is stored in different chemical reagents that are mixed before they reach the nozzle during use to keep them fresh and to maximize their potential, so that they will react fastest during cleaning. When spraying with N2, the liquid passes through a very small nozzle to form a very fine mist, so as to achieve better cleaning purposes on the surface of the silicon wafer.
This method is suitable for the removal of oxide film or organic matter. Because the chemical stays on the surface of the silicon wafer for a short time, the reaction needs a certain amount of time to clean the effect is not good. The chemical reagents used in the spray washing process are very few, which is beneficial to cost control and environmental protection.
Now remove the surface of the wafer in semiconductor factory particles and metal organic wet cleaning still is given priority to with tank cleaning, domestic semiconductor cleaning equipment mainly include Beijing sevenstar huachuang electronics co., LTD., China electronics technology group co., LTD. Commencing institute and shenyang branch companies such as semiconductor equipment co., LTD., they are all enter the industry earlier domestic equipment manufacturers, Over the years have accumulated a wealth of wet process equipment manufacturing experience. With the semiconductor factory cleaning wafer particle removal rate requirements continue to improve, more and more domestic semiconductor factories hope to use the rotating spray cleaning method, so as to introduce a single chip cleaning machine to improve the cleaning effect, and the domestic start late, mostly imported equipment. It is reported that Hua Lincona Semiconductor Equipment Co., Ltd. has reached a strategic cooperation agreement with Taiwan Hongsu Co., Ltd. Both sides will take this opportunity to deepen cooperation in the field of 8 inches and 12 slots in the single-chip rotary cleaning equipment, electroplating equipment and other high-end equipment of new product research and development, production and sales.
In the manufacturing process of various integrated circuits, with the continuous innovation and joint application of cleaning methods, the current wafer cleaning process is no longer a simple manufacturing step, but a systematic cleaning project. Silicon wafer cleaning technology innovation and development, intensify research and development, promote the cleaning equipment manufacturing enterprises is not only producing equipment, from a certain perspective, the need according to each of the specific conditions of the silicon wafer production enterprises to provide different custom cleaning solution and equipment design, help customers minimize cost and reduce the loss, At the same time as far as possible to reduce cleaning equipment itself may bring stain. The future wafer cleaning equipment will be integrated, integrated and fully automatic direction development.