Page 12 - PEN eBook May 2023

SEMICONDUCTORS
Slicing and
Surface-Finishing
Solutions for SiC Wafering
By Maurizio Di Paolo Emilio, editor-in-chief of Power Electronics News
Today, silicon carbide is used in demanding
semiconductor applications like trains, turbines,
electric vehicles and smart grids. Due to its physical
and electrical properties, SiC-based devices are
suitable for applications in which high temperature,
high power density and high operating frequency are
common requirements. Although SiC power devices
enable advancements in demanding sectors like EVs,
5G and IoT technologies, the production of high-quality
SiC substrates offers multiple challenges to wafer
manufacturers.
Amazingly, the biggest potential is still in front of
us. SiC-based semiconductors, which serve as the
foundation of technology, will continue to enable
significant advancements in a variety of fields,
including automotive, consumer electronics, aerospace
and medicine. Currently, automotive applications
dominate the SiC market and make up more than 75%
12 MAY 2023 | www.powerelectronicsnews.com
of the total power SiC device market. The accelerating
adoption of SiC results in a CAGR of 34% in the
forecast period of 2021–2027.
SiC APPLICATIONS
SiC is the chosen substrate material for advanced
semiconductors, particularly for power electronics, to
manage the growing demands of electronic devices.
It allows 15× greater breakdown voltages, a 10×
stronger dielectric breakdown field and a 3× stronger
thermal conductivity. Additionally, SiC has a 2× to 3×
higher current density and allows for higher operating
temperatures (up to 400°C, versus 150°C for silicon).
SiC semiconductors are in higher demand across a
variety of industries due to its performance at high
temperatures, voltages and power levels. SiC power
supplies, for instance, are used in data centers to
significantly reduce the amount of power needed for
SEMICONDUCTORS
cooling systems. Uninterruptible power supply systems SOLUTIONS THAT OPTIMIZE AND
also guarantee a constant, reliable source of power. BOOST YIELDS
Another application is the augmented power needs of Pureon performs testing and produces data with its
5G base stations, which handle an increasing amount own polishing and surface laboratories because it is a
of data. SiC semiconductors provide higher power at a manufacturer of consumables with internal
smaller size and are used for megahertz switching. wafer-processing capabilities. This feature offers
customers representative data to reduce risk in the
BENEFITS FOR THE AUTOMOTIVE testing and qualification of new products, as well as
INDUSTRY dramatically reduced development cycle times for
The automotive industry benefits from the advantages Pureon. The testing and acceptance processes are sped
of SiC in the following applications: up at the wafer makers’ facilities as a result.
▶ On-board battery charger: In this application, Wafers that are 200 mm in diameter require entirely
SiC can double the power while halving the size. new manufacturing processes and machinery. New
manufacturing technologies are being introduced
▶ On-board DC/DC converter: SiC is used to at every stage of the process to create high-volume
convert the on-board battery voltage into manufacturing processes for these new requirements.
a clean 12-VDC bus to power on-board Pureon is ideally positioned to offer SiC wafer
equipment. producers next-generation solutions, enabling the
market’s maturing by increasing productivity and
▶ Powertrain: Here, SiC helps to reduce switching lowering cost of ownership. With shorter cycle times
losses to less than 80%, with 30% smaller size. and longer consumable lifetime, Pureon’s solutions
This results in a smaller battery (less weight, optimize and boost yields.
less heat) and longer range. WHERE PUREON’S SOLUTIONS ARE
▶ Off-board DC fast-charging stations USED
Wafer blanks from the single crystal or ingot must
only the sheer volume of wafers needed to meet first be cut to prepare SiC substrates for device
The industry’s biggest hurdle will come from not
manufacture. The main method for accomplishing this
demand over the next five years but from modifying
is by precisely cutting wafer blanks from the SiC ingot
wafer parameters to match those of silicon wafers. using a multi-wire saw with a thin wire operating at
Current and next-generation production techniques
high speeds in conjunction with a diamond abrasive
will be pushed by tighter tolerances and standards. To
slurry. Figure 1 shows the general process flow for the
overcome these obstacles, innovation will be essential. manufacture of SiC wafers.
PUREON’S SOLUTIONS FOR SiC In the process of making wafers, cutting high-quality
MANUFACTURING blanks successfully at the wire-saw step is likely the
Because the market aims for power device price most crucial step because wafer-shape enhancements
parity with Si-based devices, SiC substrate producers at a later stage are very challenging to improve. When
are motivated to increase process efficiency and it comes to the wire-saw process, Pureon offers both
lower wafer-production costs. Additionally, SiC-based oil-based and non-oil-based diamond abrasive
applications and all other types of semiconductors are slurry as options. To further improve this process,
in extremely high demand, necessitating innovation in Pureon works closely with both wire-saw OEMs and
the manufacturing process. customers. The slurries’ proprietary chemistry and
categorized diamonds ensure lot-to-lot uniformity,
Most manufacturers believe that reducing process which leads to repeatable processes at the customers’
times or using less expensive consumables will save sites and increases wafer yield and quality.
costs. However, a large reduction in cost of ownership
will be attained by an increase in yield. The entire HIGH SURFACE QUALITIES AND
manufacturing process is impacted by consumables IMPRESSIVE STOCK REMOVAL RATES
and surface-finishing options. In this effort to optimize The mechanical polishing of the wafers using a
yields, the uniformity of pads, slurries and templates polishing slurry including diamonds and a polishing
from run to run and lot to lot is essential. The two pad is the next significant step in the production of
decades of product development for the SiC market SiC substrates. On double-sided, single-sided or a
and Pureon’s semiconductor experience help the combination of double- and single-sided polishing
company overcome manufacturing obstacles. tools, typical processes are carried out. The result of
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