Ultrapure Water Preparation Process for the Electronics and Semiconductor Industry

Because the water quality requirements for electronics and semiconductor manufacturing are extremely stringent, and parameters such as particles, ions, total organic carbon , and dissolved oxygen must all be controlled at extremely low levels, the ultrapure water system must be a multi-stage, precision purification process.

A typical process begins with a raw water tank. Municipal tap water is pressurized by a raw water pump and then enters the pretreatment stage. The pretreatment stage typically consists of a multi-media filter and an activated carbon filter. The multi-media filter retains suspended solids and colloids, while the activated carbon filter adsorbs residual chlorine and some organic matter, thereby protecting the downstream membrane elements. After that, the water enters a softener or antiscalant dosing system to prevent hardness ions from scaling on the reverse osmosis membranes. A security filter serves as a security barrier for the reverse osmosis system and is used to intercept fine particles.

The core desalination stage employs a two-stage reverse osmosis process. The first-stage RO removes the vast majority of dissolved salts, organic matter, and microorganisms; the second-stage RO further purifies the permeate, significantly reducing conductivity. Subsequently, the permeate enters a degassing membrane module to remove dissolved oxygen and carbon dioxide. Next, a continuous EDI unit uses an electric field and ion-exchange membranes to perform deep desalination. This unit, without the need for acid or base regeneration, can stably produce pure water with a resistivity exceeding 15 MΩ·cm.

The final polishing stage uses a polishing mixed bed resin. This resin raises the product water resistivity to above 18.2 MΩ·cm. At the same time, UV lamps are used to decompose residual TOC, while a terminal ultrafiltration or microfiltration unit filters out extremely fine particles. The piping throughout the system is constructed of PVDF or high-purity stainless steel. The circulation loop is maintained in a turbulent flow state to eliminate dead zones. As a professional industrial water treatment equipment supplier, we customize ultrapure water systems according to different process requirements to ensure that the water quality consistently meets SEMI standards and provides a fundamental safeguard for chip yield.