After TSMC announced plans to construct a new fab in Arizona, the Taiwan-based company disclosed that they are considering building new fabs in Japan and Germany. While the Arizona fab will focus on producing 5nm nodes using extreme ultraviolet lithography (EUV) technology, the new plant in Japan reportedly would focus on the 28nm node. This 28nm fab in Japan would be in addition to a 28nm fab expansion in China.
Given that the latter node was introduced in 2008 and is not regularly used today to build central processing units (CPU) and graphics processing units (GPU), the question arises, why is TSMC building not one, but three new fabs centered around 28nm node production? The answer is simple: customer demand.
And in this case, that demand is powered by devices and applications that use augmented reality (AR) and virtual reality (VR). Most of the devices, including those that use CMOS image sensors (CIS), are manufactured on 28nm to 80nm node technology. This is why major foundries, including TSMC and Samsung, are preparing to ramp up their volume production for these more mature nodes.
As a further illustration of the demand for the 28nm node, consider this: Apple is planning on manufacturing compact, high-resolution, micro organic light-emitting diode (OLED) display devices on silicon wafers, and Sony is planning on building image signal processing (ISP) devices; both companies will be using 28nm node technology.
AR overlays digital content and information onto images of the physical world captured by camera, and it is one of the biggest technology trends now. Apps like Snapchat and games like Pokémon GO first popularized AR, but the technology is predicted to become a part of our daily lives, influencing how we shop at brick-and-motor stores or drive (or not drive in the case of autonomous vehicles) our cars.
VR, meanwhile, is already widely used at work and home. While some gamers have embraced VR with a passion, advanced manufacturers regularly use VR to train employees. As for my company, Onto Innovation, we adopted and started using VR technology — in this case, Oculus from Facebook — for training and field support during the pandemic since some people could not meet face-to-face due to travel restrictions.
These incredible advancements in the use of AR and VR wouldn’t be possible without CIS. And with both AR and VR growing in popularity, there is no doubt that CIS applications will increase in the future.
The following paper presents a case study describing how to improve yield and fab productivity by implementing a frequent pattern database that utilizes Artificial Intelligence based Spatial Pattern Recognition (SPR) and wafer process history. This is important because associating spatial yield issues with process and tools is often performed as a reactive analysis, resulting in increased wafer scrap or die loss that could be prevented. The implementation of fab fingerprint technology proactively generates a pareto of high impacting process steps and tools based on a pattern score, enabling the production team to concentrate more efficiently on yield limiting events.
The demand for smartphone cameras, video conferencing, surveillance and autonomous driving has fueled explosive growth of CMOS image sensor (CIS) manufacturing in the last decade. While CIS becomes an increasingly important element in the production of today’s consumer electronics, there are unique challenges in production that must be addressed. As pixel sizes shrink, we see an inverse relationship with the number of pixels in the array increasing, which presents challenges for process control of the sensor, especially as it relates to the color filter array (CFA) and on-chip lens (OCL). With the push to 1µm and below pixel sizes, the ability to find sub-micron defects and macro-level variations within the pixel array is even more important to ensure uniform and unobstructed responses throughout the active pixel sensor array (APS).
CIS is unique from other semiconductor devices because it converts light energy into electrical signals. It is manufactured on silicon wafers similar to semiconductors and follows typical back-end packaging processes such as grinding, sawing, and electrical testing. A typical CIS device has an ASP region in the center of the die with electrical I/Os (bondpads) on the periphery. Deionized water is often used to clean up mobile contamination left behind during the wafer thinning or die singulation process which has an inherent risk of staining or leaving a residue on the APS that affects the quantization of light and is considered a killer or yield limiting defect.
Picosecond Ultrasonics (PULSE Technology) has been widely adopted as the tool-of-record for metal film thickness metrology in semiconductor fabs around the world. It provides unique advantages, such as being a rapid, non-contact, non-destructive technology, and has capabilities for simultaneous multiple layer measurement. In this paper, we describe the unique advantages of Picosecond Ultrasonics for advanced radio frequency (RF) applications. RF filter process control requires stringent metrology due to tight process tolerances. The first principles-based PULSE technology does not require external calibration standards and provides robust measurement capability for multi-layer thickness measurements. For advanced RF applications, the capability of PULSE technology to measure both velocity and thickness simultaneously for transparent and semi-transparent films offers a lot of potential for not only monitoring processes but offers insight into the device performance. The PULSE technique can also simultaneously measure full stack for multilayer metal stack measurements with excellent repeatability and long-term stability which makes process control more efficient and reliable. Fast throughput makes it possible for a high sampling rate for RF applications which is the key for device level process control and yield improvement.
The global RF semiconductor market size is growing rapidly at a CAGR of 8.5% in the next five years from 17.4 billion in 2020 to 26.2 billion USD in 2025. The rollout of 5G technology and its enabled Internet of Things (IoT) are the main driving force for this growth. Each 5G device requires up to 100 filters to make sure each band is isolated to avoid interference that will drain battery life, reduce data speeds, and cause dropped calls. RF filters are becoming more and more critical for all signal process applications. 5G devices require Bulk Acoustic Wave (BAW) filters which can work better at higher frequencies. With more and more filters to fit into a device, the size of filters is also shrinking dramatically in three dimensions. These advances in filter technology place stringent demands on manufacturing which in turn requires accurate and precise metrology techniques. Both thickness and acoustic properties of the piezoelectric layer determine the frequency response of filters. Thickness accuracy and uniformity requirements for the films are beyond what process tools can offer at deposition and there are several options available to achieve such tight controls post-deposition. Metrology techniques employed for characterizing these properties must meet the sensitivity, accuracy, and stringent repeatability requirements. The thickness of the full stack and especially the thickness and sound velocity of the piezoelectric layer are key to realizing the extremely tight process control of frequency accuracy (3σ) of 0.1% or better. A high sampling rate on a hundred-micron level device is needed to make sure all devices across the wafer can meet the requirements which require fast throughput with a small measurement probe.
Picosecond Ultrasonics (PULSE Technology) has been widely used in thin metal film metrology because of its unique advantages, such as being a rapid, non-contact, non-destructive technology and its capabilities for simultaneous multiple layer measurement. Measuring velocity and thickness simultaneously for transparent and semi-transparent films offers a lot of potential for not only monitoring process but offers insight into the device performance. In this paper, we show Picosecond Ultrasonics provides a complete metrology solution in advanced radio frequency (RF) applications. This includes measurement of various thin metal films for wide thickness ranges with extremely excellent repeatability which could meet stringent process control requirements, simultaneous multilayer measurement capability, and simultaneous measurement of sound velocity and thickness for piezoelectric films which play a key role in the performance of RF devices.