Air Purification solution for photoelectric industry
Photovoltaic silicon wafer is made of silicon material. It is the raw material of semiconductor integrated circuit chip. It is as bright as a mirror. At present, the rapid development of Microelectronics Industry, Integrated Circuit Technology has entered the era of less than 0.18 microns, greatly stimulated the development of photovoltaic new energy silicon wafers, at the same time, the performance parameters of photovoltaic silicon wafers have been improved greatly, so the development prospect of photovoltaic silicon wafers is very optimistic.
1.1 The production process of photovoltaic new energy silicon wafers from a large perspective, the production of photovoltaic new energy silicon wafers includes two major parts: the production of silicon single crystal rods and the production of photovoltaic new energy silicon wafers, subdivided into the following main processes: Single Crystal Rod growth-single Crystal Rod cutting and testing-external diameter grinding-slicing-chamfering (round edge)-grinding/grinding plate inspection-etching (chemical etching, LP-CVD + AP-CVD process)-PTA heat treatment-back damage treatment-polishing (ML rough polishing, ML fine polishing)-cleaning-quality inspection-clean packaging from single crystal rod growth to outer diameter grinding for silicon single crystal rod production process, after the slicing process for photovoltaic new energy silicon wafer production process. Taking a Japanese silicon wafer factory as an example, this paper introduces the design scheme of air-conditioning purification system and automatic control system in the production process of photovoltaic new energy silicon wafer. 1.2 environmental control of each production process requires a silicon wafer factory to produce 4-6 inches of new photovoltaic energy silicon wafers with an output of 4.8 million wafers per year. The company's photovoltaic silicon wafers are used in the manufacture of discrete devices, power components and special integrated circuits. 2. Air Conditioning Systems The design of air-conditioning purification is closely combined with the layout of the process and the flow of production. Different types and different uses of plant air-conditioning purification system have their own characteristics, the following introduces photovoltaic new energy silicon wafer production process of air-conditioning purification system program.
2.1 Air Conditioning System 1 slicing room, chamfering room, grinding room only temperature control requirements, set air-cooled heat pump split cabinet type air conditioner (PAC) to ensure room temperature requirements, indoor machines placed nearby in the workshop, duct, the double-layer Louver outlet is used for side air supply, and the outdoor machine is placed on the roof. The fresh air is supplemented by S1-1 and S1-2 of direct evaporative heat pump type roof air conditioner. There are dust-proof requirements in the workshop. The air-cooled heat pump split-cabinet type air conditioner is equipped with a medium efficiency filter (air dust counting efficiency: ≥60% , for particles ≥1 m) at the return air outlet, and the roof type air conditioner is also equipped with a two-stage filter. Here's how it works:
Furnace Room, BSD room only temperature control requirements, set air-cooled electric heating split Cabinet Air Conditioner (Pal) to ensure room temperature requirements, indoor machine placed in the workshop nearby, the air duct, using square diffuser top air supply mode; The outdoor unit is placed on the roof. Fresh air is coming from the adjacent clean rooms. There are dust-proof requirements in the workshop. A medium-effect filter is installed at the return air outlet of the air-cooled electric heating split cabinet type air conditioner (Air Dust counting efficiency: ≥60% , for particles ≥1 m) . There are temperature and humidity control requirements in the grinding room, the air-cooled electric heating split cabinet air conditioner (Pal) is set to ensure the room temperature requirements, the indoor machine is placed nearby in the workshop, the air duct, using square diffuser top air supply mode; The outdoor unit is placed on the roof. FRESH AIR BY FRESH Air Unit (MAU-1,2) after processing, connected to the supply pipe sent to the indoor, relative humidity by fresh air unit to ensure. The fresh air unit is shared with the purification system. There are dust-proof requirements in the workshop. The air-cooled electric heating split cabinet type air conditioner is equipped with medium efficiency filter at the return air outlet (Air Dust counting efficiency: ≥60% , for ≥1m particles) . The fresh air unit is equipped with coarse and medium efficiency filter. 2.2 fresh air air conditioning units (Mau) and circulating air conditioning units (Ahu) used in the purification system are cooled at 6-11 °C, heated with 0.2 MPA steam and humidified with 0.1 MPA clean steam, clean Steam is produced from pure water through a clean steam generator. The purification level of 1CP room is 7, the air change rate is 30 times per hour, the acid content of process equipment in CP room is more, the air conditioning mode of all fresh air air conditioning unit (Mau-3) + HEP-ABOX is adopted. Its airflow flow is: Fresh Air inlet-coarse filter-medium effect filter-preheater-surface cooler-heater-clean steam humidifier-blower-duct-high efficiency filter air supply-clean area. 2 ML room clean grade is 7, air change frequency is 30 Times/hour, adopt the air conditioning mode of MAU + AHU + HEP-ABOX. Fresh air from other systems common MAU-1,2 fresh air group. 3cp/CVD room, LP/CVD room, clean packing room purification level is 6, Air Change Times is 50 times per hour, the air conditioning mode of MAU + Ahu + HEP-ABOX is adopted. The fresh air is supplied from MAU-1 and 2 fresh air units shared by other systems. 47,6 clean room adopts the air flow form for the top high-efficiency filter air supply outlet, the room under the LOUVER air return. The air flow is: New Return Air Mixing! Medium efficiency filter-surface cooler-air blower-air duct-high efficiency filter air outlet-clean area-lower Louver Return Air outlet-return air duct-new return air mixture.
The clean room and the quality inspection room are of Grade 7, adopt the air conditioning mode of fresh air unit (Mau) + circulation unit (Ahu) + Fan Filter Unit (FFU) . Using the air flow form for the top FFU air supply, the room under the lower louver air return. The concentration of NH4 + and SQx is required in the clean room and quality inspection room. A chemical filter should be installed in the circulation unit (Ahu) . The air flow in the 5-stage cleaning room is as follows: fresh return air mixing-chemical filter (NH4 +)-chemical filter (SQx)-medium efficiency filter-surface cooler-blower-supply duct-supply duct-supply plenum-fan filter unit (FFU)-clean area-lower Louver Return duct-return duct-new return air mixing. The fresh air is supplied from MAU-1 and 2 fresh air units shared by other systems. 6 The fresh air for the clean room except CP is centralized treated by 2 new air units (Mau-1,2) , and the fresh air is centralized treated and sent to all circulation units (Ahu) . The air flow is as follows: FRESH AIR INLET-COARSE FILTER-MEDIUM EFFECT filter-preheater-surface cooler-heater-clean Steam humidifier-blower-air duct-air conditioning units (Ahu) . 7CP Room, ML room and clean room use more acid, the diffuser plate of air outlet of high efficiency filter in CP room and ML room should be made of stainless steel plate, and the net plate of FFU in clean room should be made of stainless steel plate. Also note that the quality inspection room according to process requirements need to use black wall panels, black roof, the corresponding use of black air return, the network board of FFU need to use black screen. 3. The automatic control of the air conditioning system
Fresh Air Unit (MAU-1,2) using frequency conversion fan, by the main air supply pipe static pressure sensor to control the converter. An Electric Control Valve is arranged on the fresh air pipe connecting each air volume and positive pressure control circulation unit (Ahu) , and the opening of the electric control valve is adjusted by the positive pressure value of each clean room, the positive pressure value of the clean room does not change with the change of the air volume of the production equipment. The change of the open degree of the Electric Control Valve causes the change of the static pressure on the total air supply pipe. According to its setting value, the fan frequency of AHU-1 and 2 is adjusted, in order to gain control. 3.1 the temperature and humidity of the purification workshop control the humidity of the purification workshop is ensured by the fresh air units MAU-1 and 2, and the supply air condition point of the fresh air units is controlled, according to the set value of the air supply state, the opening of the electric actuator of the dry steam humidifier and the electric two-way valve on the surface cooler and the return water pipe of the heater are adjusted. The dew point temperature DPT is continuously set by the humidity sensor HE in the inspection room. The temperature of the purification workshop is guaranteed by the circulation unit Ahu, and the opening of the electric two-way valve on the return water pipe of the surface cooler is adjusted according to the indoor temperature. 3.2 the first stage pump is used in the cooling system to control the chilled water system, and the number of the chillers, pumps and cooling towers is determined by the method of load control. The pressure differential flow bypass valve between the supply and return water main pipe is automatically controlled according to the set pressure difference between supply and return water
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