Advancing Semiconductor Inspection with SWIR Cameras

Semiconductor Review | Wednesday, July 12, 2023

Short-wave infrared (SWIR) cameras are critically enhancing semiconductor inspection for a high sensitivity capability, enabling the detection of tiny defects and thus, improvising fabrication efficiency.               

FREMONT, CA: Integrated circuits, which are built upon semiconductor platforms, serve as the foundation for various technological advancements, encompassing electronic devices, sensors, and solar panels. Given the escalating demand for these platforms, the semiconductor sector is projected to reach a valuation of one trillion USD by 2030. This remarkable growth can be attributed to the widespread application of integrated circuits in electric vehicles, data storage, and wireless communications, among other fields.

The increasing need for efficient and reliable manufacturing processes is emphasising the importance of advanced semiconductor wafer inspection technologies, which involve the imaging of semiconductor chips at various stages of fabrication to detect defects. However, the semiconductor inspection process is often costly and time-consuming, requiring multiple integrated steps to produce a single chip. Despite its prolonged duration, this process has become an essential requirement rather than an optional one in the semiconductor industry. Consequently, the semiconductor inspection market is expected to grow from five billion USD to 8.9 billion USD by 2031.

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To meet the demands of the semiconductor industry, manufacturers are increasingly adopting fast and high-resolution imaging solutions for chip inspection, which accelerates the fabrication rate. As a result, innovation leaders in this field are employing cutting-edge cameras and conducting groundbreaking research to enhance yield and efficiency in critical industries worldwide.

Deploying Short-wave Infrared Vision

Semiconductor devices are primarily constructed using silicon wafers, which are typically not transparent to visible light. However, they exhibit a high transmission rate in the short-wave infrared (SWIR) spectrum, enabling greater transparency at wavelengths above approximately 1,050 nm. This characteristic has led to the widespread utilisation of SWIR sensors for chip inspection in camera technologies. In particular, many systems employ indium gallium arsenide (InGaAs) sensors, known for their sensitivity range of 900 to 1,700 nm.

The illumination of silicon semiconductor chips with SWIR light enables cameras to detect minute features such as micro-cracks and contaminant particles. To observe these small features and failures, businesses need to achieve a favourable signal-to-noise ratio. This is where highly sensitive cameras play a crucial role, striking a vital balance between the necessary sensitivity for SWIR detectors in semiconductor inspection and pixel resolution practices. The sensitivity of a camera is directly linked to the size of its pixels, making it challenging to simply reduce pixel sizes for the best solution. Therefore, efficient alternatives are required.

In contrast to visible cameras, which typically aim for the smallest available pixel size to obtain high-resolution images, SWIR cameras face challenges due to the lack of natural light in the short-wave infrared spectrum. Searching for tiny defects under these conditions can strain the available light budget. As a result, business leaders are considering a trade-off by opting for larger pixel sizes, such as 20 microns, to detect even the smallest items and address failures within a limited range.

Advantages of SWIR Camera

These SWIR cameras utilise internally developed InGaAs photodiode detector arrays with 20-micron pixel diameters, enabling them to achieve speeds of up to 300 Hz in full frame. They are meticulously designed to provide the utmost normalized sensitivity currently available in the market, accompanied by an expanded dynamic range. Moreover, these cameras commonly feature a standard industrial interface and triggering capabilities, making them invaluable for manufacturing clients. By employing a normalised sensitivity approximately 20 per cent higher than their market competitors with smaller pixel sizes, these cameras aim to deliver high-resolution images of superior quality.

Resolution and speed are recognised as crucial metrics in semiconductor technology. However, for a product to be considered truly plug-and-play, it must meet additional criteria such as easy integration and compatibility with existing manufacturing infrastructure. The SWIR cameras manufactured by the company are designed to address these requirements and offer seamless integration.

The company's product series, known as Dione CAM, not only covers the SWIR spectrum but also successfully targets the long-wave infrared (LWIR) range. This has garnered significant interest from semiconductor wafer manufacturers due to its ability to effectively monitor thermal defects. The Dione series incorporates commercially available microbolometers in its sensor setup.

In addition to SWIR cameras, the company offers a range of products for wafer inspection. Some of these products support high-speed data transmission, such as 10 Gigabit Ethernet (10 GigE), and can achieve resolutions of up to 47 megapixels. On the other hand, their Atlas model cameras boast resolutions of up to 31 megapixels and are renowned for their robustness and ability to deliver over 5 GigE. The company is also pushing the boundaries of innovation in this field, with plans to release a new version of their existing model camera, featuring an impressive 65-megapixel resolution.

The semiconductor industry and its competitors are increasingly recognising the growing demand for SWIR cameras in semiconductor inspection, including UV cameras, which can potentially be deployed in various stages of the chip manufacturing process.

SWIR technology has transformed semiconductor wafer inspection, providing a significant boost in accuracy, efficiency, and cost-effectiveness. Detecting defects and impurities effectively enhances quality control measures while reducing production time and costs. SWIR cameras boast impressive operational speeds, facilitating the swift inspection of large volumes with ease. A standout characteristic of SWIR lies in its unique capacity to penetrate materials like silicon, enabling enhanced visualisation of subsurface defects. Consequently, this feature contributes to heightened product reliability and performance. Moreover, SWIR's non-destructive nature minimises damage to delicate wafers, resulting in reduced material waste. Given the continuous advancements in the semiconductor industry, SWIR technology has become indispensable for the production of high-quality semiconductors, fostering innovation and enabling the creation of cutting-edge devices.

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