Application of Pure Silica in Electronics and Semiconductor Industries

What is Silica and Why is it Important in Electronics and Semiconductor Industries?

Silica or silicon dioxide (SiO2) is the most abundant mineral compound in the Earth's crust and makes up a large part of its weight. This material is found in nature as quartz, cristobalite, and tridymite crystals, as well as in amorphous (glassy) form, and humans have used it for centuries in the production of glass, ceramics, casting, and building materials. However, in the past century, pure silica has found a completely different and vital role in the electronics industry: the base material of mode semiconductors.

Today, no computer, smartphone, television, mode car, or industrial equipment can be imagined without semiconductor components, and almost all these components begin a jouey in which silica plays a key role. From quartz crucibles used for silicon crystal growth to insulating oxide layers inside transistors, substrate glasses for displays, and silica filler powder in component packaging, silica is present at all stages of electronic component production.

The importance of silica in the semiconductor industry goes back to several unique features: very high thermal stability, electrical insulation, optical transparency, chemical resistance, abundance, and affordable price compared to other materials. This very combination of features has made silicon extracted from silica the most widely used element in the electronics industry after oxygen, and silica products have found a strategic position in this industry's supply chain.

In this article from Amiran Stone Mineral Project, producer of mineral materials, we intend to comprehensively examine the application of pure silica in the electronics and semiconductor industries. In the following sections, we will cover:

• Crystalline structure and physical and electrical properties of pure silica
• The path of crystal and semiconductor wafer production from silica
• The role of silica as an insulator and dielectric layer inside circuits
• Application of silica in electronic glasses, displays, and optical fibers
• The presence of silica in the packaging and assembly of electronic components
• Quality standards, grading, and purity control of silica
• Market trends, challenges, and conclusion

It is worth noting that silica supplied by Amiran Stone Mineral Project with a grading of 10 to 450 mesh is mainly introduced for applications such as glass, casting, ceramics, and building materials. However, a deeper understanding of the properties and applications of silica helps engineers, buyers, and industrial managers make more informed decisions in selecting materials for their production processes.

Structure and Properties of Pure Silica; Why is this Material Unrivaled in Semiconductors?

Pure silica exists in both crystalline and amorphous (glassy) states. In the crystalline state, silicon and oxygen atoms are arranged in a regular three-dimensional network, the most important forms of which are quartz, cristobalite, and tridymite. In the amorphous state, the same atoms sit together without long-range order and form silica glass. This very structural difference enables silica to be used in diverse applications, from large-volume melting crucibles to a few-atom-thin layers inside transistors.

One of the most prominent properties of silica is its thermal stability. The melting point of pure quartz is around 1710 degrees Celsius, and silica glass can be used at temperatures above 1000 degrees Celsius without deforming or losing its insulating properties. This feature is vital in semiconductor wafer production processes that deal with high temperatures and long thermal cycles.

Electrically, silica is considered a very good insulator. Its band gap is about 9 electron volts, which severely restricts the passage of electric current. Its relatively low dielectric constant, low loss at high frequencies, and excellent resistance to breakdown voltage have made it an ideal insulator for tiny and dense transistors. In addition, silica has perfect chemical and structural compatibility with silicon and forms a natural protective layer on the wafer surface during thermal processes.

Other important properties of silica include: low thermal expansion coefficient, high transparency in the visible and ultraviolet spectrum range, and excellent chemical resistance to most acids (except hydrofluoric acid). These properties allow silica to provide stable performance in the harsh thermal and chemical environments of the semiconductor industry while also enabling precise processing and forming.

But all these properties only make sense if the purity is high. In the semiconductor industry, even very small amounts of impurities such as iron, aluminum, sodium, potassium, or boron can disrupt component performance. Alkali metal impurities in silica glasses cause ionic drift and current leakage, while transition metals can act as recombination centers in the silicon crystal structure. For this reason, silica used in the electronics industry must have a much higher purity than silica for general uses such as glassmaking, ceramics, or casting.

In practice, silica purity is expressed as a percentage of SiO2 and in terms of ppm (parts per million) or ppb (parts per billion) of impurities. Silica with a purity of about 99.5 percent is sufficient for many glassmaking, ceramic, and casting applications, while advanced semiconductor applications may require a purity of 99.99 percent and higher. This huge difference distinguishes the supply chain, production methods, and quality control standards of each sector from one another. Producing electronic-grade pure silica requires advanced chemical purification processes, including acid washing, controlled precipitation, and calcination at high temperatures.

From Silica to Wafer; The Crystal Production Path in Semiconductors

The starting point for producing any semiconductor component is the extraction of silicon from silica. High-purity quartz is melted with carbonaceous materials in electric arc fuaces at temperatures close to 2000 degrees Celsius to produce metallurgical-grade silicon (MG-Si) with a purity of about 98 to 99 percent. This material is then upgraded through complex chemical processes such as distillation and decomposition of trichlorosilane into electronic-grade silicon (polysilicon) with very high purity, which is the raw material for growing silicon single crystals.

At the heart of this process, silica appears once again in the form of quartz crucibles. In the Czochralski (CZ) method, the most common crystal growth method, polysilicon is melted in a high-purity quartz crucible. This crucible must have high thermal stability, chemical purity, and mechanical resistance so that impurities do not leak into the melt during the several-day crystal growth process and undesirable reactions with the molten silicon are prevented. The quality of the quartz crucible directly affects the quality of the final crystal, the number of crystal defects, and production yield.

In addition to its reactive role, silica as a material itself is used in the form of quartz wafers in the semiconductor industry. Quartz wafers, with their low thermal expansion coefficient, transparency in the ultraviolet range, and high thermal stability, are used in photolithography, optical masks, and temperature-sensitive substrates. Also in SOI (Silicon on Insulator) technology, a layer of silica is placed under the active silicon layer to increase device speed and reduce power consumption and parasitic effects.

Another important application is the use of silica glass in process equipment. Tubes, wafer boats, and other components inside diffusion and deposition fuaces are all made from high-purity silica glass to be in direct contact with wafers at high temperatures without introducing contaminants into the process. These examples show that silica is not just a distant raw material in the semiconductor industry, but is present at all stages of production.

It should be noted that these processes require precise control of the grading and chemical composition of the primary silica. The selection of particles with the right size and distribution affects the reaction speed in the fuace, melting uniformity, and ultimately the crystal quality. Also, precise management of impurities at all stages, from the mine to the fuace, is an inseparable part of producing silicon with acceptable quality for the electronics industry.

Silica as Electrical Insulator and Dielectric Layer in Integrated Circuits

One of the most important applications of silica in the electronics industry is its use as an insulating layer within the structure of transistors and integrated circuits. In fact, the industrial success of silicon as the main semiconductor material largely retus to its oxidizability: silicon in contact with oxygen forms a protective and insulating layer of SiO2 on its surface, the quality, density, and uniformity of which are unparalleled among semiconductor materials.

In the thermal oxidation process, the silicon wafer is placed in special fuaces and in an atmosphere of oxygen or water vapor, at temperatures of 800 to 1200 degrees Celsius, so that a layer of silica with controlled thickness grows. These layers can have a thickness of a few atoms and still provide stable electrical performance. This very capability has made the production of key transistors such as MOSFETs at the nanometer scale possible.

The main applications of silica layers inside circuits include the following:

• Gate Oxide: a very thin layer between the gate and the transistor chael that controls the electric current.
• Field Oxide: a thicker layer that separates the active regions of the device from each other.
• Shallow Trench Isolation (STI): to prevent current leakage between adjacent transistors.
• Inter-Layer Dielectrics (ILD): to keep the metallic wiring layers separated.
• Protective and encapsulating layer for the chip surface against environmental contamination.

With the advancement of transistor miniaturization, the gate layer thickness fell below a few nanometers, and silica was replaced in this specific role by materials with a high dielectric constant (high-k) such as hafnium oxide due to increased quantum tueling current. Nevertheless, silica is still widely used as an intermediate layer, trench insulator, and in advanced structures such as FinFET, and has maintained its position as the main insulator of the semiconductor industry.

In addition to thermal oxidation, silica layers are also produced by chemical vapor deposition (CVD). In these processes, gaseous precursors containing silicon decompose on the wafer surface and form a layer of SiO2. This method is used to coat surfaces that caot be thermally oxidized or to produce silica glasses with modified properties, such as phosphosilicate or borophosphosilicate (BPSG) glasses. The combination of these methods allows insulating layers with precise thickness and composition to be produced tailored to the needs of each generation of components.

Application of Silica in Electronic Glass, Displays, and Optical Fibers

The electronics industry is not limited to wafers; displays, optical fibers, sensors, and optical equipment also make up a large part of this industry, and in many of them, silica-based glasses play a key role. Substrate glasses in liquid crystal displays (LCD), OLED panels, touch screens, and protective covers are all produced with a high percentage of SiO2 and controlled thermal, optical, and mechanical properties.

In mode displays, the glass substrate must have high optical transparency, a very flat surface, and a thermal expansion coefficient compatible with other layers of the device. High-purity alkali-free silica glasses are the standard of this industry. The production process of these glasses requires silica with controlled grading and chemical composition; if silica grading in glassmaking is not selected correctly, problems such as melting non-uniformity, gas bubbles, optical quality loss, and increased energy waste in the fuace occur.

Optical fibers, which are the backbone of mode telecommunication networks, are made from very high-purity silica glass. In an optical fiber, both the core and the cladding are formed from silica glass with different refractive indices, which are controlled by adding impurities such as germanium or fluorine. These fibers can transmit optical signals for tens of kilometers without amplification, something that is only possible with glass of unparalleled quality and minimal optical loss.

In addition, silica glasses are used in LED lamps, optical sensors, lasers, precision lenses, and protective windows for optical equipment. Silica's transparency over a wide range of wavelengths, from ultraviolet to infrared, has made it an ideal material for optical applications. Also, silica-based glass-ceramics are used in the electronics industry for component packaging, temperature-resistant substrates, and components of laboratory equipment; products that are obtained by controlling the crystallization of silica glass and offer a combination of glass formability and ceramic resistance.

In all these applications, the quality of the primary silica, from purity to particle size and grading distribution, plays a decisive role in the properties of the final product. For this reason, advanced glass producers always work with suppliers who can provide precise laboratory reports and consistency in products.

The Role of Silica in Packaging, Assembly, and Durability of Electronic Components

After chip production, the stage of packaging and assembling components begins, and silica plays a prominent role in this stage as well. One of the most important applications is the use of silica powder as a filler in epoxy molding compounds, which makes up a large part of the weight of these materials. These compounds protect sensitive chips against moisture, thermal shock, contamination, and mechanical damage, and are used in the production of components such as microcontrollers, memories, and power circuits.

Adding silica to resins creates several key advantages: it brings the thermal expansion coefficient of the compound closer to silicon, improves thermal conductivity, reduces costs, and increases dimensional stability. Without these fillers, the difference in thermal expansion between the chip, substrate, and resin during the thermal cycles of the device causes coections to break and early component failure.

In addition to molding compounds, silica is used in the following applications in electronics packaging:

• Conductive and non-conductive thermal adhesives and pastes for mounting components on heatsinks
• Potting and sealing materials to protect components against moisture
• Ceramic substrates for power circuits and high-power LEDs
• Solder masks and protective coatings on the printed circuit board
• Composite materials in making protective enclosures and thermal components

In power circuits and high-power LED components, silica-based ceramic substrates (such as alumina-silica compounds) are used due to their insulation and suitable thermal conductivity. These substrates allow the dissipation of heat generated in the component while retaining their insulating properties at high temperatures.

Choosing the right silica for these applications depends on factors such as particle size, size distribution, purity, particle shape, and moisture behavior. Very fine (micron and nanometer) particles provide a larger surface area and create better packing, while coarser particles are more suitable for applications requiring high density. The combination of these factors determines the final performance of the component and its lifespan in the working environment.

Quality Standards, Grading, and Purity Control of Silica

In the electronics and semiconductor industries, silica quality control is a critical matter. Silica quality standards include multiple parameters: SiO2 percentage, type and amount of impurities, particle size distribution, moisture, color, and surface properties. Each of these parameters can affect the production process and the quality of the final product, and for this reason, reputable manufacturers choose suppliers capable of providing precise laboratory reports.

Mode analytical methods such as ICP-MS, XRF, and X-ray diffraction (XRD) enable the measurement of impurities at the ppb level. In the semiconductor industry, there are very strict limits on alkali metals, transition metals, and radioactive elements, because these elements can degrade component performance over time. In addition, silica quality standards in mode manufacturing industries include requirements regarding batch uniformity, traceability, packaging, and transportation.

Silica grading is measured by the mesh unit: the mesh number shows how many holes are in each inch of the sieve. Therefore, a higher mesh number indicates finer particles. Silica supplied in the market is usually available in a range from 10 to 450 mesh, each suitable for a different application. Coarse particles are used for building materials and filtration, middle sizes for glassmaking and ceramics, and very fine particles for filler applications, high-quality glasses, and advanced materials.

Silica produced by Amiran Stone Mineral Project is offered with a grading range of 10 to 450 mesh for the main applications of glass, foundry products, ceramic products, and building materials. This variety in grading allows customers to choose the product according to their needs. For sensitive applications, buyers can consult with technical experts to select the best option based on their production process.

Finally, proper storage and transportation of silica is also part of quality management. Moisture absorption, contamination by airboe particles, and contact with rusty metals can reduce silica quality. Proper packaging with resistant bags and standard pallets minimizes these risks and maintains product uniformity from production to consumption.

New Trends, Challenges, and Conclusion

The electronics and semiconductor industries are undergoing a major transformation: artificial intelligence, 5G networks, electric vehicles, and the Inteet of Things have increased the demand for more, faster, and more efficient chips. This growth has sharply raised the demand for pure silica in all sectors of the supply chain, from crystals and wafers to advanced glasses and packaging materials.

The trend of transistor miniaturization has created new challenges for silica: thier insulating layers, the need for higher uniformity at the atomic level, and more precise control of impurities. Also, the development of new technologies such as 3D processors, chiplets, and advanced packaging has increased the need for materials with optimized thermal and mechanical properties. In response, material producers are developing modified silicas, particle spheroidization, and nanometer fillers.

On the other hand, the diversity of silica applications is not limited to the electronics industry. This material plays a role in glassmaking, ceramics, casting, building materials, and the metal industries; for example, granulated silica in metal industries is widely used due to its thermal resistance and chemical properties. This diversity has tued silica into one of the strategic mineral materials in the global economy.

In this article, we examined how pure silica is applied in the electronics and semiconductor industries: from quartz crucibles for crystal growth and quartz wafers, to insulating layers inside transistors, display glasses, optical fibers, and component packaging fillers. The unique properties of this material — thermal stability, electrical insulation, optical transparency, and abundance — have made it an irreplaceable material in the electronics industry.

Choosing the right silica for each application requires a precise understanding of process needs and material properties. Amiran Stone Mineral Project, by offering silica in a grading range of 10 to 450 mesh for glass, casting, ceramics, and building material applications, strives to meet the diverse needs of industrial customers. Consulting with technical experts can help you in choosing the right product.

This article was prepared using technical information provided by Amiran Stone Mineral Project (mineral producer) and this group's silica product page.