Interview conducted by Olivia FrostMay 4 2021In this interview, Dr. Chady Stephan, PhD, the Applied Markets Leader at PerkinElmer, talks to AZoM about the current trends shaping semiconductor wafer manufacturing.
To begin, can you give us an introduction into the Semiconductor Industry?
A semiconductor is a material whose ability to conduct electricity increases as its temperature rises. That is, it sometimes acts as a conductor and sometimes as an insulator. Its conducting ability relies on the electronic properties of the semiconductor materials to function properly. These materials typically include silicon, germanium, and gallium arsenide, as well as organic semiconductors.
Semiconductor device fabrication is the process used to manufacture semiconductor devices, typically the metal–oxide–semiconductor (MOS) devices used in the integrated circuit (IC) chips that are present in everyday electrical and electronic devices. It is a multiple-step sequence of photolithographic and chemical processing steps during which electronic circuits are gradually created on a silicon-based wafer made of pure semiconducting material.
The semiconductor industry is ever-evolving, following Moore’s law observation and projection on the number of transistors on a microchip or Integrated circuit (IC) doubling every two years. Manufacturers and R&D facilities are constantly looking to improve processes by utilizing purer chemicals and reagents thus needing sensitive and reliable analytical testing solutions. Equipment is required to provide low detection levels of critical impurities which seamlessly integrate with on-line sampling accessories for real-time monitoring to provide improved efficiencies and production uptime.
Next, can you tell us about semiconductor wafer manufacturing and its production steps?
Wafers are sawed out of a block (ingot) of very pure crystalline silicon. The wafer is then polished and functionalized via materials deposition or modification based on the intended use. The resist is applied to a spinning wafer to achieve a uniform layer. At this stage, we have a functionalized wafer that will undergo various rounds of lithography - a manufacturing process that utilizes lenses, shrinks a mask pattern, and projects it onto the wafer. The chip patterns are burned into the resist in an exposure step. The print is developed through etching and heating followed by ion implantation.
The resist is then removed through various washing steps. This cycle is repeated 30 to 40 times and sometimes more before the processing cycle is complete and a single chip layer is fabricated. The wafer will hold many chips based on its size. The chips are then cut out and used in various electrical and electronic devices.
What are some of the current trends in the semiconductor industry?
Aside from the race towards the next node size, enabling smaller, faster, and improved computational power is important. The four major trends that will shape the semiconductor industry are:
Automation
Wide range of microchips, fusion, and system-on-a-chip devices, all requiring increasing numbers of sensors.
Electrification
Electrification of powertrains by government regulations, driving goals, and growth of hybrid and electric vehicles.
Digital Connectivity
Connections to inside & outside of the vehicle - Internet of Things (IoT). Creating platforms for infotainment and connectivity from vehicle to vehicle for driverless technology.
Security
Prevention of the interconnectivity of the vehicle's systems from failing; causing catastrophic issues and prevention of being maliciously hacked; creating driving problems.
How are these trends shaping semiconductor wafer manufacturing and how has this changed/developed in the last five to 10 years?
The above-mentioned trends along with increased demands for consumer, communication, data processing, and industrial electronics evolved the industry to use more advanced or modified silicon-type wafers. Silicon carbide wafers, as an example, are used in optoelectronics, solar inverters, and industrial motor drives due to their thermal capabilities while silicon germanium and Gallium Arsenide (GaAs) are finding ways to advance applications in silicon-based lasers.
When it comes to semiconductor wafer testing, what are some of the biggest obstacles the industry currently faces?
The industry trends highlighted above are certainly making semiconductor wafer testing more difficult. The major challenge is around scale, with the size of devices becoming smaller and smaller, requiring instrumentation with increasingly improved detection limits. A small defect or contamination on a large device would not have such an adverse effect as the same defect on a much smaller device.
Manufacturing processes that have been satisfactory in the past for fabricating large devices may not be applicable to smaller devices and may lead to flaws. Materials used in the manufacturing and cleaning processes need to be of increasing purity. There are several cleaning processes involved from raw material to final products and each step has the possibility of either improving the cleanliness or introducing contamination into the process. Great care is required in the choice of materials and their application.
In addition, to move forward and to cope with the increased demand for devices the industry may need to move to alternative materials which will require a whole new suite of methods and possibly additional analytical techniques.
In terms of failure analysis and QA/QC, what are some of the challenges, and how can these be overcome?
There are a series of challenges that need to be overcome to obtain the perfect final product. These all fall into the category of wafer defect management and the problems can be introduced at any stage of the manufacturing process. Hence, testing at multiple stages of the wafer manufacturing process is required starting at the beginning of the process with the raw materials. Multiple analytical techniques can be deployed to determine elemental and organic composition as well as physical testing of the materials.
After the starting materials are introduced into the manufacturing process there will be a wafer functionalization process where a functional surface combines the properties of the substrate and the functionalized group to produce a material that can combine aspects of each. Additionally, coatings may be applied to the wafers to assist with wafer processing or to achieve the required functionality for further processing. In each of these cases, the presence, content, and uniformity of the coatings need to be determined.
And finally, any residual impurities could have a negative impact on the performance of the wafer and/or the final manufactured device. So, control and detection of impurities are essential throughout the manufacturing process.
In terms of routine QA/QC analysis, it is essential to have reliable instrumentation and software that is easy to use, can run standard methods, and be suitable for the environment it is to be used in. For quality control and failure analysis, the instrumentation must be versatile and offer the highest performance to overcome a range of problems.
Can you tell us a bit about the MappIR accessory with Spectrum 3™ FT-IR system?
The PerkinElmer Spectrum 3TM MappIR system enables the automated measurement of a silicon wafer over the complete size range of wafers available, ranging from 2” (50mm) up to 12” (300mm). It allows for the collection of FT-IR spectra in either transmission or reflectance sampling modes and to run standard wafer FT-IR methods. The major benefit of the MappIR system is the ability to perform these automated measurements at multiple points on the wafer using either standard preset patterns or user-customizable patterns.
Hence, the consistency of the silicon wafer critical parameters can be determined across the entire wafer rather than just at 1 point in the center of the wafer. Consistent quality across the entire wafer is required since each wafer will produce many individual components when processed. The software controls the measurement position, data collection, and data analysis according to the method and calculation required.
Also, a range of standard FT-IR silicon wafer applications can be performed using the system including carbon and oxygen determination, measurement of coatings and dielectrics, and film thickness determination.
How important is the Spectrum 3™ FT-IR system – what does it offer that might not already be available in the market?
The Spectrum 3TM FT-IR is a truly versatile FT-IR platform for the Semiconductor and associated industries. In addition to the MappIR system capabilities discussed above, the range of capabilities and applications possible with Spectrum 3TM span much wider than just silicon wafer measurements. The Spectrum 3TM tri-range system offers software-automated access to Near-, Mid- and Far-Infrared spectral ranges, each range has its own selection of interchangeable sampling modules.
For example, the PerkinElmer EGA 4000 is a unique sampling module allowing TG-IR hyphenation integrated into the sample compartment of the Spectrum 3TM, thus allowing testing of thermal degradation of components used in fabrication. In the mid-IR region, the Spectrum 3TM can be used for rapid raw materials ID using the Universal (Attenuated Total Reflectance) ATR accessory. In addition, the Spectrum 3TM can be equipped with a PerkinElmer SpotlightTM 200i FT-IR microscope or Spotlight 400 FT-IR Imaging system for device troubleshooting, such as detection and identification of contaminants and defects as well as testing for coating uniformity or failures. The flexible platform can be expanded to meet evolving needs and provides a complete solution for all your applications.
PerkinElmer Spectrum Touch software enables methods developed through a simple, “push button” operator user interface, minimizing training needs. Any methods, data, results, or spectral libraries can be stored and retrieved from the Cloud using the PerkinElmer NetPlus for IR software, enabling the consistent global implementation of methods and greater collaboration.
Where can readers find more information?
Readers can find additional information related to MappIR, Spectrum 3TM FT-IR, and PerkinElmer resources for Semiconductors through the links provided below:
MappIR Accessory for Wafer Analysis
PerkinElmer Spectrum 3 FT-IR
PerkinElmer Semiconductor & Electronics
About PerkinElmer
PerkinElmer is a global leader committed to innovating for a healthier world. Our dedicated team of 12,500 employees worldwide is passionate about providing customers with an unmatched experience as they help solve critical issues especially impacting the diagnostics, discovery, and analytical solutions markets. Our innovative detection, imaging, informatics, and service capabilities, combined with deep market knowledge and expertise, help customers gain earlier and more accurate insights to improve lives and the world around us.
About Dr. Chady Stephan
Dr Chady Stephan holds a PhD in Analytical Ch
emistry from Université de Montréal. He worked as a project manager for QSAR risk assessment services before he joined PerkinElmer as an Inorganic Product Specialist supporting the various elemental analysis platforms. A thought leader in elemental analysis with over 20 peer-reviewed papers and book chapters, he is currently leading a multifunctional team composed of marketing, technical marketing, application scientist, and strategists focusing on delivering complete solutions for Applied Markets at PerkinElmer.
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