Development direction of diamond wire silicon wafer cutting equipment
1) High line speed and high production capacity support the reduction of single GW investment
According to the theory of fracture mechanics and the properties of silicon materials, when the maximum cutting depth of diamond abrasive grains is greater than the critical cutting depth of silicon materials, the transition from plastic cutting to brittle fracture cutting will occur. Therefore, within the allowable range of the diamond wire load, appropriately increasing the steel wire speed in the multi-wire cutting process is beneficial to the removal of the silicon material in the ductility domain, and the quality of the silicon wafer surface will be improved. The table below shows the comparison of cutting under different line speeds. With the increase of line speed, the process time is shortened, and the daily production capacity of a single machine is increased.
Table 1 Comparison of cutting at different wire speeds
For silicon wafer cutting equipment manufacturers, while considering cost reduction, it is necessary to further improve the overall stability of the equipment, especially the stability of tension control, the stability of the spindle bearing box and the strength of the equipment. At present, the mainstream slicing line speed in the market is 1800~2100 m/min. Since 2017, the increase of slicing machine line speed has begun to differentiate. By 2019, some diamond wire slicing machine manufacturers are subject to technical route selection and their own research and development capabilities. The limit is maintained at 1800m/min, and a few manufacturers with strong R&D capabilities continue to increase the line speed to 2400m/min, raising technical barriers. With the improvement of cutting equipment and diamond wire technology, the wire speed will also be further improved. The future development trend is expected as follows
Table 2. Development trend of slice line speed
The increase of cutting wire speed, combined with the enhancement of diamond wire cutting capacity, shortens the cutting time of each knife and increases the daily production capacity of each equipment. In 2016, nearly 40 slicers were needed per GW of production capacity, but at present, with the increase in line speed and loading capacity, only 16 slicers per GW of production capacity; For the improvement of single chip power, in the near future, the investment per GW slicer will be less. Therefore, investment in fixed assets, as well as later water and electricity costs, maintenance costs, and labor costs will be reduced for companies that plan new production capacity and plan to increase production capacity.
2)The miniaturization of cutting equipment supports the reduction of the floor space of a single GW workshop
The slicer needs to achieve higher stability and high line speed. In addition to focusing on the research on the spindle motor, the lubrication and cooling of the main roll, the accuracy of the cutting chamber of the main roll, and the cutting cooling and lubrication system, it is also necessary to optimize the overall structure of the equipment. The take-up and pay-off paths of diamond wire need to be further shortened to reduce tension fluctuations. While the performance of cutting equipment will be improved in the future, the overall structure will be more compact and miniaturized. The reduction of the floor space of a single device also greatly reduces the floor space of a single GW plant for a new plant, so it can reduce the investment cost of the plant to a certain extent.
