Engineers seeking to use SiC devices must consider performance and cost considerations when selecting an appropriate wafer for their application. Prime grade substrates provide optimal quality while research grade wafers offer more cost-effective alternatives for non-critical purposes.
Before silicon carbide (SiC) wafers can be used in device fabrication, they must first be cut to shape. This can typically be accomplished using a multi-wire saw in combination with diamond abrasive slurry.
High Temperature Stability
SiC’s ability to withstand high temperatures is essential for semiconductor processing. Thanks to its strength and chemical purity, SiC is frequently used as wafer tray supports or paddles in semiconductor furnaces; furthermore, its thermal stability makes it a key component in temperature and voltage controllers such as thermistors and varistors.
SiC is available in different forms known as polytypes, distinguished by the stacking arrangement of silicon and carbon atoms. Each polytype offers differing electrical properties which impact device performance and reliability, which engineers select based on operational conditions and desired performance characteristics.
At the heart of SiC substrate preparation for device fabrication lies cutting wafer blanks using a wire saw, an essential step that contributes to downstream wafer shape enhancements such as bow and warp improvements, depending on its quality of cut. Important factors include selecting appropriate diamond abrasive polishing slurry and pad combos as well as speed and feed settings for this step.
High Breakdown Voltage
With the rapid evolution of 5G and other technologies, high power/high voltage semiconductor devices have become ever more essential. Silicon carbide (SiC) makes an excellent material choice for such high-performance electronic devices due to its superior thermal and electrical properties.
Due to SiC’s wide bandgap, its critical electric field is significantly greater than that of silicon (Si). Furthermore, there is less dependence on crystal orientation when conducting electron-initiated multiplication and hence significantly higher impact ionization energy in SiC pn junctions compared with Si devices at any given breakdown voltage.
Producing high-quality SiC wafers requires optimizing several key inputs, including choosing an ideal polishing slurry, choosing an optimal pad and polishing technology combination, and selecting an appropriate machine. Pureon has extensive experience optimizing these processes resulting in increased material removal rates, wafer shape consistency and surface quality.
Low On-State Resistance
Silicon carbide (SiC) is an advanced semiconductor with a wide bandgap that makes it suitable for operation at high temperatures, in addition to possessing superior electrical and thermal conductivity properties, making it the perfect material choice for many different applications, from electric vehicle batteries and 5G devices to IOT applications.
However, the performance of any power device is determined by its on-state resistance. A significant barrier to efficiency that could hinder its operation in demanding environments.
Manufacturers of SiC wafers have set themselves the challenge of decreasing on-state resistance of their devices by increasing doping density of their n-layers, so as to increase effective mass of electrons accelerated within it and more likely undergo impact ionization along 0001. This increases energy required for electron acceleration until they reach breakdown voltage, thus decreasing on-state resistance of SiC FETs.
High Efficiency
SiC wafers were originally developed for industrial abrasive applications; today however, their impact can be felt throughout power electronics applications. With Moore’s Law nearing its conclusion, electric vehicle manufacturers and aerospace applications are looking towards SiC for significant efficiency gains and device longevity improvements.
SiC’s potential must be realized, however, through a substrate capable of withstanding the rigorous process of wafer production. Blanks must successfully pass through the wire saw step with minimal bow, warp and total thickness variation (TTV).
Crystal growth optimization – including temperature gradients, gas flow rates and impurity levels – is critical to the production of SiC ingots with minimal defects, yet final dicing makes or breaks wafer performance. Thanks to scribing and break techniques used in glass cutting for decades – the final dicing step will determine the quality of SiC wafers produced; here, the scribing and break method promises significant enhancement. As a result of its superior yielding process it enables fabrication of power devices with exceptional electrical performance and superior reliability.
High Mechanical Strength
SiC is an exceptionally hard and wear-resistant material, making it the ideal material for demanding environments. Due to its strength, power electronics devices can operate at higher temperatures and voltages without incurring performance losses, as well as creating smaller devices with lower parasitic resistances.
Producing SiC wafers can be a complex and time-consuming task, necessitating the selection of polishing slurry and pad, along with precise processing parameters designed to achieve low surface roughness on their wafer surface. Pureon’s decades-long history in developing products for this industry provides invaluable assistance for manufacturers seeking reliable processes for producing these substrates.
Careful consideration of wafer specifications and vendor capabilities ensures customers choose Prime or Research grade SiC wafers to best match their project goals while adhering to budget constraints. By doing this, they can take advantage of both technologies while taking full advantage of each one’s advantages.
High Durability
Silicon carbide (SiC), with decades of application in industrial abrasives and automotive brakes, makes an excellent material choice for high temperature radiation-resistant applications. Furthermore, SiC’s properties make it suitable for next-generation power devices.
Superior thermal and mechanical properties further amplify SiC wafers’ performance advantages. Their efficient heat dissipation enables superior device efficiency, while their hardness protects it from damage and wear-and-tear in demanding environments.
Wafer manufacturers’ efforts to achieve cost parity with silicon devices and navigate supply chain constraints related to electric vehicle (EV) growth will force them to innovate and invest in improvements. Selecting either Prime or Research grade wafers directly impacts these intrinsic characteristics; so taking time to carefully examine specifications and vendor capabilities are vital steps toward making your project a success.
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