Technical requirements and key points of manufacturing process for CMP slurry filtration membrane

Die grinding is a process used in the semiconductor industry to shape and polish silicon wafers and other materials used to make integrated circuits. Liquid filtration membranes play a vital role in this process as they are used to remove particles and impurities from the slurry to ensure consistent grinding performance and prevent contamination of the wafer surface.

The following are technical requirements for liquid filtration membranes used in chip grinding applications:
1. In terms of filtration efficiency, the membrane should be able to effectively remove particles and impurities in the grinding fluid, and the filtration level is usually in the range of 0.1 to 1 µm (micron). Slurries used for filtration should have a consistent and controllable particle size distribution to prevent equipment clogging and ensure uniform etching or polishing of semiconductor wafers. There are no absolute specifications, but particle size requirements depend on the specific process steps and the type of equipment used Variety. As in the chemical mechanical polishing (CMP) process, the slurry typically contains abrasive particles with a controlled particle size distribution in the 50-500 nm range. In contrast, in an etch process, the slurry may contain smaller particles in the 10-100 nm range, which can achieve high precision requirements.

2. Chemical compatibility. When selecting membrane materials, compatibility with chemicals and additives used in the grinding fluid should be considered to avoid degradation, swelling or other adverse effects on membrane performance. Chip polishing fluids typically contain a mixture of abrasive particles, chemicals to adjust pH and viscosity, and additives such as silicon dioxide (SiO₂), aluminum oxide (Al2O₃) or ceria (CeO₂) to control polishing performance and prevent particle agglomeration materials, acids or bases used to control the pH of the slurry, surfactants to reduce surface tension and prevent foaming, and buffers to maintain a stable pH. Typically in silica-based polishing slurries, hydrofluoric acid (HF) is added to adjust the pH and produce a more uniform polishing effect, such that compatibility is a technical factor that must be considered in membrane selection of.

3. Thermal stability, the membrane should be able to withstand the temperatures encountered during grinding, ranging from ambient to elevated temperatures. In the chemical mechanical polishing (CMP) process, the slurry temperature is usually controlled in the range of 20-40°C, but in other polishing processes, the temperature can be higher, such as electrolytic polishing or electrochemical mechanical polishing (ECMP), the slurry The temperature can go from room temperature up to 70-80°C.

4. Mechanical strength. The membrane should have sufficient mechanical strength to withstand the pressure difference and flow rate encountered in the grinding liquid filtration system. In this case, the high-strength composite membrane should be the primary consideration in the selection.
5. Low fouling, the membrane should have low fouling characteristics, which means it should be able to resist the accumulation of particles and impurities on its surface, which will cause the filtration performance to decline over time.

Regarding the process methods for producing such membranes, including phase inversion, interfacial polymerization and electrospinning, orbital etching, etc., the choice of production method will depend on the required membrane material, structure and performance characteristics, as well as the The degree of uniformity of particles in a liquid. There are several technical factors in production that must be observed:
1. Selection of raw materials, to ensure that the quality of raw materials (such as polymers, solvents and additives) used in membrane manufacturing is stable.
2. Monitoring and control of process parameters such as temperature, pressure and concentration during production to achieve desired membrane performance.
3. Strict quality control measures are implemented, including in-process testing and inspections, to ensure that the membranes meet the required specifications.
4. Due to the precision and particularity of wafer-like semiconductors, appropriate post-treatment processes are used to achieve the best results, such as washing, drying, annealing, etc., to improve the performance and stability of the film.
5. Evaluate the filtration performance of the membrane in terms of particle retention, flux, anti-fouling, etc., to ensure that it meets the requirements of grinding applications.

Citation

1."Filtrationof Chemical Mechanical Planarization (CMP) Slurries for Advanced ICManufacturing" by A. Singh and R. Singh, Chemical Engineering &Technology, 2014. This article discusses the importance of CMP slurryfiltration in semiconductor manufacturing and provides an overview of differenttypes of filtration membranes used in CMP processes.

2."A NovelFilter Membrane for Chemical Mechanical Polishing Slurry Filtration" by H.Wang, et al., Journal of Materials Science and Chemical Engineering, 2016. Thispaper describes the development of a novel filter membrane for CMP slurryfiltration, which was found to have superior filtration performance compared toconventional membranes.

3."Filtrationof CMP Slurries Using Membrane Filters" by J. Choi and K. Lee, Journal ofthe Korean Ceramic Society, 2013. This article discusses the use of membranefilters for CMP slurry filtration and provides information on the selection offilter membranes based on pore size, material, and surface properties.

4."AMembrane-Based Filtration System for High-Performance Chemical MechanicalPlanarization (CMP) Slurries" by S. Kim and K. Lee, Journal ofMicroelectromechanical Systems, 2010. This paper describes the development of amembrane-based filtration system for high-performance CMP slurries, which wasfound to provide efficient and reliable filtration performance.