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Thermal oxide silicon wafer or SiO2 wafer contains a silicon oxide layer which is formed on a bare silicon wafer surface at elevated temperature in an oxidant’s presence through thermal oxidation process. Thermal oxidation is obtained by exposing silicon wafer to a combination of oxidizing agents and heat to make a layer of silicon oxide or SiO2. The layer is most commonly made with hydrogen and/or oxygen gas, although other halogens can be used for this purpose. The growth of silicon oxide layer takes place in an ambient air to about 20Å thick.   

Thermal oxidation on silicon wafers can be performed in two ways – rapid thermal processing or RTP method, and wet thermal oxide processing. In the RTP process, the wafer is exposed to rapid heating to over 1,000 °C for a very short period of time, and then slowly cooled down to room temperature to prevent cracking. In the wet thermal oxide method, a mixture of hydrogen and high-purity oxygen is burnt at nearly 1,000 °C, which results in the production of water vapor. Although the method may not produce a very high quality end product and may not be used as a masking layer, it is advantageous in the way it produces a higher growth rate than dry oxidation.

SiO2 wafers that meet your specific requirements 

Thermal oxide silicon wafers are used in electronics industry as a semiconductor or dielectric material, or integrated in Micro Electro Mechanical Systems (MEMS) devices. WaferPro provides high-quality SiO2 wafers in a variety of dimensions ranging from 2” to 300 mm. This trusted supplier of best quality thermal oxide silicon wafers ensures that your specific requirements are met by choosing prime grade and defect-free silicon wafers as a substrate so that a high uniform layer of thermal oxide is formed in the furnace. In micro-technology, Silicon dioxide (SiO2) is the main insulating material. Thermal oxidation is commonly used to produce an insulating oxide layer.

Silicon reacts with oxygen, leading to a moving interface towards the substrate. Dry oxidation is carried out at temperatures between 850 and 1200 °C and demonstrates low growth rates. This leads to the production of a high-quality oxide for MOS gate insulation. In cases where highest quality thin silicon oxide layer is required, then dry oxidation is the preferred method to obtain SiO2 wafers than wet oxidation.

WaferPro provides below three types of SiO2 wafers:

Dry Thermal Oxide on Both Sides of Wafer

Dry Thermal Oxide on Single Side of Wafer

Dry Chlorinated Thermal Oxide with Forming Gas Anneal

Silicon is the second most common element found on earth’s crust, and the seventh most abundant element in the universe. Silicon wafers are used as substrates for semiconductors in our everyday electronics including mobile phones, televisions, laptops, and other circuitries. Silicon wafer is obtained as a thin slice from pure silicon crystal that possesses almost the same properties as the mother crystalline semiconductor substance. Silicon crystal must be pure, it is only allowed to have only one non-silicon atom out of a billion silicon atoms. However, this makes it insulator as pure silicon is non-conducting, so some impurities called dopants, like boron and aluminum, are added to it to obtain the desired level of conductivity from it. The silicon wafer thus obtained can be used as a substratum for different electrical, electronic, and other gadgets.

Silicon wafers are available in different types, the most common ones being polished wafers which are polished either on one side or both sides. At WaferPro, the world’s leading provider of the highest quality silicon wafers of various types and grades, you can find the flattest and most cleaned wafers for use in various applications. Hi-wafers or Hydrogen Annealed Wafers have a high BMD density and excellent gate oxide quality. AT wafer is heat treated in Argon gas to prevent diffusion of dopant from the wafer surface and have a flat resistivity profile in depth.

Wafer size is an important factor in chip production 

Silicon wafers usually come in circular shapes, and their diameter is measured in millimeters. A 300 silicon wafer means the wafer has a diameter of 300 mm, which is a big improvement over the one inch wafer as the increased size results in reduction of the high volume chip fabrication. The size of 300 silicon wafer is an important factor in chip production, as a small change in size can result in significant increase in the yield per wafer. 300 silicon wafers are fast replacing 200 mm silicon wafers in integrated circuits (ICs) due to their low cost.

300mm silicon wafer available at the WaferPro have higher yield per wafer, compared to other larger diameter silicon sags, and which is one-tenth inch and a half inch, hence it is larger than a 450 mm sag. The diameter of a 300 silicon wafer is about 775 microns thick which is crucial to prevent breakage. The thickness of 300 silicon wafers is also critical for economic feasibility and device yield, while the diameter is critical for back thinning.

300 silicon wafers offer a variety of benefits 

Silicon wafer, also known as silicon substrate or dice, is obtained from the silicon ingot. It acts as a substrate for microelectronic devices and is used in integrated circuits (ICs) due to its conductive properties and affordability. Silicon is the second most abundant material in the earth’s crust, and is found in beach sand, quartz, flint, and agate, among others. For use in electronic devices, silicon substrates must be covered with metal. Metallic thin films are deposited on silicon wafers to form conductive pathways. Common metals used for this purpose include copper, nickel, chromium, germanium, and gold. Metal alloys like platinum and tantalum may also be used. Vacuum deposition methods such as sputtering, filament evaporation, and electron beam evaporation are used for this purpose.

Silicon wafers or silicon substrates can be doped (impure) or undoped (pure). Doped silicon wafer is also known as extrinsic or degenerate wafer, while a doped wafer is also known as intrinsic wafer. Doping, or adding impurities to the wafer, helps in changing the electrical conductivity of silicon. If the doping amount is high, the silicon wafer is known as degenerate, but if the doping amount is low or moderate, it is known as extrinsic type.

P-type and N-type silicon wafers 

There are two types of doped silicon substrates: P-type and N-type. In P or Positive substrate, a positively charged material like boron is doped while in N-type substrate, a negatively charged material like phosphorus or arsenic is added. Silicon substrate is made from a super-flat semiconductor material. It can be made using many methods like Czochralski (CZ) pulling method, and Float Zone (FZ) growth method.

Polished silicon substrate is used in a variety of applications including microfabrication, imaging, and experiments. Two grades of silicon substrates are usually offered, standard silicon wafers for use in standard applications and medium-resolution imaging, and ultra-flat silicon wafers requiring high-resolution imaging. Silicon wafer substrates can be used for sample substrates, biological substrates, and thin film research.

Silicon wafers are widely used in a variety of applications, such as:

Semiconductor manufacturing

Home appliances

Computers and smartphones

Thin film deposition

Artificial intelligence (AI)

MEMS fabrication

microchips

Transistors, rectifiers, and diodes

Opto-electronic components

High-power applications (detectors and sensors)

Get different types of silicon wafers with custom specifications 

WaferPro is the world’s leading supplier of different types of silicon wafers with custom specifications. The company has a selection of Prime Semi Standard CZ wafers in stock at all times, which can be shipped in a day all over the world. WaferPro offers below types of silicon wafers to its worldwide clients:

Prime Silicon Wafer: Also referred to as Device Grade or Particle Grade wafer, it has tighter specs for thickness, bow, warp, and cleanliness. This type of silicon wafer is used in semiconductor devices, particle monitors, and lithography.

Test Silicon Wafer: Also referred to as Monitor or Dummy wafer, it has a wider spec than prime wafers. It is used in equipment setup & testing, and production process evaluation.

Reclaimed Silicon Wafer: The wafer is made to go through either a wet thermal oxide or dry thermal oxide process to grow a thermal oxide or silicon oxide (SiO2) layer on the wafer, which is commonly used as a dielectric layer and in MEMs devices.

Silicon wafer is used as a semiconductor in electronic devices. This super flat disk is refined to a mirror-like surface. Silicon dopants can be added throughout the growth process to include aluminum, boron, nitrogen, gallium, indium, etc. with an aim to increase its conductivity. Silicon wafer acts as a substrate for microelectronic devices. Although silicon crystals may look metallic, they are not entirely metallic. A pure silicon crystal is nearly as good as an insulator as it allows very little electricity to pass through it. The electrical properties of silicon crystals can be changed by adding dopants or impurities like boron and aluminum that change its behavior.

For a semiconductor to be formed out of non-conductive silicon, it must be turned into a wafer.

To make a silicon wafer, the material is extracted from sand, and heated till it melts into a high-purity liquid of about 99.9999999% purity, only one out of a billion silicon atoms can be a non-silicon. It is then allowed to solidify into a rod or ingot using Floating Zone (FT) or Czochralski (Cz) process. It involves the placement of a small piece of solid silicon in a pool of molten silicon which is then pulled slowly in rotation, transforming the liquid into a cylindrical ingot in the process. The ingot is then sliced into thin wafers as per the manufacturer’s specifications using sharp diamond saw blades.

Uses of silicon wafers 

The thickness and diameter of the wafer must correspond to the mechanical strength and other physical qualities of the material. The finished product must be sturdy enough to support its weight. Sliced wafers must be processed before they can be used in manufacturing. Machines and abrasive chemicals are used to polish the wafer’s surface to a perfect smooth finish. Silicon wafers are used in electronics and computing, semiconductors, optics, and aviation for insulating delicate tools from extreme temperatures.

Factors affecting the cost of silicon wafers 

Silicon wafer price is determined based on many factors. The total cost of silicon wafer increases with its size, although the cost per unit surface area decreases as the large wafer areas reduce the price of the die. The effect of dopants on the cost of silicon wafers is quite small compared to other factors that may impact its cost when you buy silicon wafers. Wafers with orientation are primarily used for doping, All other factors being equal, the cost of the silicon wafer with orientation is slightly less.

Best quality silicon wafers at the best price 

Sapphire is a single crystal of Al2O3 with a hexagonal crystalline structure. Sapphire crystal has desirable optical properties as it can transmit wavelengths from 150 to 6000 nm. When the crystal is appropriately thinned, it becomes useful at wavelengths close to its transmission limits. Being a rhombohedral crystal, some properties of sapphire would depend upon the crystallographic direction which is specified relative to the optical C-axis of the crystal. It is highly resistant to thermal shocks while the crystal’s thermal conductivity is very good at low temperatures.

Sapphire wafers are used for dissipating heat in electronic devices due to their light transmitting properties and corrosion resistance. The wafers' extremely high thermal conductivity at low temperatures make them excellent material for heat dissipation in cryogenic environments.

Sapphire is extremely hard, and is second in hardness only to the natural mineral diamond. It has a Mohs hardness of 9, and it is also extremely scratch-resistant - the properties that make it suitable for use in many industries. In SOS integrated circuits, layers of silicon oxide are formed over a sapphire substrate that provides it with a dielectric layer on top for efficient conduction of electricity across the circuit.

High-performance Silicon (Si) and Germanium (Ge)-based devices can be manufactured with the help of a sapphire substrate that speeds up the performance of chipsets. The presence of silicon and germanium ensures high electron mobility and low twin defect density in the chipsets. Radiofrequency devices that are manufactured using SiGe perform better than those that make use of Silicon-on-Sapphire (SOS) wafers.

Some of the common uses of sapphire wafers are provided below:

Microelectronic IC applications

Hybrid microelectronics

Infrared detectors

Silicon-on-Sapphire (SOS)

High temperatures

Radiation resistance

Growth substrate

Polishing carriers

Hostile environment

Sapphire wafers are made by cutting the crystal bar which is followed by grinding and polishing. The semiconductor wafer is cut into a wafer by a wire-cutting machine. Grinding is done to improve the flatness, curvature, and parallelism deviation of the sapphire wafer before polishing, and to reduce the thickness of the damaged layer caused due to cutting.

Following a standardized process of manufacturing sapphire wafers

WaferPro follows a standardized process of manufacturing sapphire wafers. The sapphire crystal rod position is accurately located on the slicing machine to ensure precise slicing. The process of slicing cuts the sapphire crystal rod into thin wafers while grinding is done to remove the chip cutting damage layer caused due to the process of slicing. Chamfering is done to trim the wafer edge into a circular arc to improve the mechanical strength of the sapphire wafer edge. Polishing improves the roughness of the wafer and its precision, while cleaning removes contaminants on the wafer surface. Finally, quality inspection is done on the wafers using high-precision testing instruments for surface dust particles, flatness, etc., to meet the customer’s expectations.

Best quality sapphire wafers in different planes