April 24, 2020

Using Fused Quartz in Silicon Wafer Processing

Semiconductor-grade silicon

Semiconductor-grade silicon is the first-choice substrate material for advanced electronics applications. Critical building blocks for a limitless range of microelectronics components, silicon wafers must first be cut from monocrystalline or polycrystalline ingots. Fused quartz is a key enabling technology for the rapidly expanding semiconductor wafer industry.

Currently valued in excess of USD $9.85 billion, the global market for silicon semiconductor wafers has forecasted an enormous growth trajectory in the coming years. Estimates suggest the industry will top USD $13.64 billion by 2025.

To meet this extraordinary demand, process engineers require long-lasting, high-performance solutions at various critical points in the production cycle. Fused quartz fibers, quartz crucibles, and rigid silica components are increasingly used to meet the electronics industry’s growing demands.

In this article, Saint-Gobain Quartz will briefly explore how fused quartz products are used in the silicon wafer processing production chain.

Silicon Wafer Processing: From Ingots to Wafers

The process of generating defect-free monocrystalline silicon (c-Si) wafers begins with a single seed crystal of silicon and a specialist furnace. A vertical rod with the seed crystal on the tip is dipped into a silicon melt, then gradually drawn upwards and rotated. Dopant elements are added to the melt to modulate the electronic properties of the semiconductor. This melt is characterized by exceptional in-process temperatures (1425 °C / 2597 °F), requiring a highly-stable crucible – typically based on fused quartz.

Large single-crystal ingots, also called boules, are obtained by carefully controlling the pulling rate, rotation rate, and temperature gradients. Wafers are then extracted from these boules using a series of machining processes, typically diamond wire sawing followed by chemical mechanical planarization (CMP) to achieve the necessary thickness and planarity for electronic applications. These parameters are essential for meeting the demand for device miniaturization, enhanced digitization, and high electronic mobility.

Benefits of Fused Quartz in Wafer Processing

The challenges of silicon wafer processing center around its high energy demands and extreme temperatures. The process is highly sensitive to any chemical disturbance and zero contamination policy arise in Silicon wafer processing. Fused Quartz is then a material of choice as its chemistry is very close to the manufactured product. Fused quartz then excels in such conditions, with an outstandingly low coefficient of thermal expansion in the region of 0.54 x 10–6/K –1 and a purity above 99,99%.

In fact, fused quartz crucibles are the industry-standard for crystal growth via the Czochralski process.

Read our previous article to learn more about: Applications of Fused Quartz Crucibles

Intermediate quartz products based on continuous high-purity SiO2 (>99.95%) fibers such as quartz felts and quartz wool are also routinely used as thermal insulators in Silicon manufacturing process throughout the substrate production line for very specialized usages. Thanks to the mechanical behaviour of non-woven Quartzel® products, to their thermal insulation properties and to their compatible chemistry, it is possible to design various type of thermal insulation systems from simple ones (direct usage of Quartzel® felts or wool) or more complex design such as heating baffles (by combining Quartz wool with Quartz glass).

Keeping all said properties with the added value of unprecedented infrared (IR) reflectivity, our ceramic-like product made of Quartz fibers, SilPower®, has also proven useful as an alternative to costly materials like gold which gradually erodes over time. SilPower® is a material of choice to combine with IR lamps where its behaviour is proven to be overall better than gold and unlike coatings is unaffected by vacuum. Thanks to its diffuse reflectivity, it allows an optimal thermal performance in wafer processing chambers allowing a precise thermal gradient monitoring. It can also be used as a rigid thermal insulator with high IR blocking power to replace other materials.

Fused quartz goods essentially offer improved performance over extended life cycles to support the ever-growing demand for defect-free monocrystalline silicon wafers.

Want to learn more about using fused silica in Semicon and Solar applications? Contact a Saint-Gobain Quartz sales representative today.

Saint-Gobain Quartz: Products for Silicon Production

Saint-Gobain Quartz specialises in high-purity fused quartz products for silicon semiconductor processing. We also provide a range of solutions suitable for several other market sectors, including the aerospace sector.

Otherwise, contact a member of the Saint-Gobain Quartz team today with any questions about our fused quartz prices or quartz product offerings.

Reference: https://www.mordorintelligence.com/industry-reports/semiconductor-silicon-wafer-market