The filter press was used to produce the recyclable high-purity silicon cake.
The filter press was used to produce the recyclable high-purity silicon cake.

TSMC Pioneers Physical Regeneration Technique for Backgrinding Wastewater

Recycled Industrial-grade Silicon Products Are Introduced into Steel Industry to Realize Circular Economy
P.H. Chiou
Yu-Wu Chen
Fu-An Wu
Kidd Hsu

TSMC’s waste management strategies primarily focus on circular economy and source reduction. A large amount of wastewater can be generated during the semiconductor advanced packaging process. In 2020, TSMC led the industry to initiate the physical regeneration technique without for wastewater treatment. By January 2021, TSMC has saved the use of more than 55 metric tons of chemicals. In addition, the products are transformed from inorganic sludge into high-purity industrial-grade silicon. TSMC has sold out the first batch of silicon products in December 2020, achieving a circular economy with innovation. Taking a step further, the silicon products will be used as deoxidizer in the steelmaking process.

Creating Industrial-grade Renewable Raw Materials without Chemical Additives

Backgrinding wastewater mainly consists of water and silicon particles, which has recycling potential for economic value. The industry commonly uses coagulation, flocculation, and sedimentation to separate suspended solids from backgrinding wastewater. This conventional water treatment not only consumes chemicals but also increases impurity in wastes, reducing the possibility of reuse. Based on the assessment of increasing recycling value, TSMC has led to the launch of the Backgrinding Wastewater Recycling Project in 2019. TSMC’s Facility Division collaborates with suppliers to evaluate filter cloth specifications suitable for silicon particles. Through three months of repeated system testing, the Company successfully extended the existing plate-and-frame filter press to produce the recyclable high-purity silicon cake.

TSMC’s Backgrinding Wastewater Recycling Process

In July 2020, a backgrinding wastewater recycling system was officially launched in the Advanced Backend Fab 3. By January 2021, TSMC recycled 15,000 metric tons of backgrinding wastewater and generated 30 metric tons of industrial-grade silicon products. Acting as a leader in the semiconductor industry, the Company developed a fully physical plate-and-frame filter press system to convert backgrinding wastewater into valuable silicon products. With great effort, this innovative technology completely replaced the chemical coagulation process. Due to its advantage of no added chemicals, the discharged water from the filtration process meets TSMC’s secondary water standard after treated by reverse osmosis. As of January 2021, reclaimed water reused in TSMC’s manufacturing processes reached 12,750 metric tons in total.

Cooperating with Vendors to Improve the Quality of Industrial-grade Silicon Product

To further meet the market expectations of silicon products, TSMC visited downstream industry and potential acquirer in December 2020. After understanding the back-end procedure and application, the Company planned the refined strategies, including manufacturing process modification, system update, and production standard adjustment. TSMC not only enhanced the purity but also improved the shape of silicon products progressively in favor of maximizing resource recycling and accelerating market application. Backgrinding Wastewater Recycling Project is going to be introduced to Advanced Backend Fab 2 Phase 2 and Advanced Backend Fab 6 in 2022, continuing to achieve the goal of resource sustainability.

TSMC’s Backgrinding Wastewater Recycling Project