In manufacturing, inspection is one of the most critical processes for maintaining consistent product quality. For surface and visual inspection, area cameras and line scan cameras are commonly used, while in some industries manual visual inspection is still widely adopted. In recent years, however, CIS-based inspection systems using CIS line scan cameras have become increasingly popular in these applications.
In this article, from the perspective of a dedicated CIS manufacturer, we introduce the role CIS line scan cameras play in industrial inspection and explain how they are used in semiconductor-related inspection processes.
CIS (Contact Image Sensor) is a compact imaging device that highly integrates image sensors, light sources, and lenses into a single all-in-one unit. Using rod lenses, it forms an image directly on the sensor and captures it line by line in close proximity to the target object. This structure provides excellent stability and resistance to vibration while enabling installation in space-constrained environments. Because the image is captured at a 1:1 ratio, there is no edge blur or image distortion typically associated with conventional optical systems.
CIS technology has been widely used in financial equipment such as ATMs, as well as office automation devices including printers and scanners. As the name “Contact Image Sensor” suggests, conventional CIS devices were originally designed to scan objects in direct contact with the sensor surface. As a result, the working distance (WD)—the distance between the glass surface and the target object—was extremely short, typically less than 0.5 mm, and analog output was the mainstream interface.
To meet the growing demands of a wide variety of surface and visual inspection applications, CIS technology has continued to evolve. Modern CIS line scan cameras retain the core advantages of conventional CIS devices while offering enhanced performance, including longer working distances, higher scanning speeds, and digital interfaces.
In semiconductor inspection processes, it goes without saying that resolution and pixel count are key factors when selecting a camera. In actual production environments, however, engineers often face a variety of additional constraints and challenges.
As a CIS line scan camera manufacturer, we frequently receive inquiries related to the following issues:
With conventional camera systems, lenses are used to magnify or reduce the image, which can introduce distortion around the edges of the captured image. In addition, depending on the size of the wafer or inspection target, multiple cameras may be required. This increases the need for lens and lighting adjustments, as well as post-processing tasks such as image stitching.
Furthermore, inspection systems using area cameras or conventional line scan cameras often require significant installation height to achieve a wide field of view and high resolution. In some inspection environments, however, securing enough space for such large-scale camera systems can be difficult.
Against this background, CIS line scan cameras have emerged as an effective solution that can achieve both high-precision inspection and space-saving system design.
Here, we introduce two actual examples of CIS line scan camera implementation in semiconductor inspection applications.
In the first case, limited installation space was a major challenge for wafer edge inspection. To address this issue, we provided a customized configuration in which the sensor unit and digital processing box were separated, allowing the system to fit within the available space.
In the second case, the application involved inspection of wafer surface scratches and contamination, requiring not only installation in a confined space but also high resolution and high-speed scanning performance. In response, we proposed a solution featuring a separated sensor and digital box configuration, along with a CIS line scan camera supporting 2400dpi (approx. 21μm resolution) and a CoaXPress 2.0 interface. This enabled us to deliver a system that met the customer’s inspection requirements.
Both applications utilized our proprietary illumination structure designed to suppress diffuse reflection from wafer surfaces. In addition, because dust control is essential in wafer manufacturing environments, fanless cooling CIS line scan cameras were adopted in both systems.
Beyond these examples, CIS line scan cameras are also used in a wide range of semiconductor inspection applications, including wafer ID inspection, wafer notch inspection, and chip appearance inspection.
As mentioned earlier, we do not simply offer standard CIS line scan cameras. Instead, we propose optimized solutions based on each customer’s inspection application and installation requirements.
One of the key elements we focus on in customization is the lighting solution. Standard CIS line scan cameras include built-in illumination, but depending on the inspection target, lighting conditions can significantly affect image quality. For this reason, we also offer external lighting options.
By using our external light source together with the CIS line scan camera, illumination intensity and lighting timing can be controlled directly from the CIS camera side, helping reduce adjustment time and simplify system setup.
We can provide customization in the following areas:
*Products are proposed based on the required conditions and operating environment please contact us for the details.
In advanced manufacturing industries such as semiconductors, inspection processes today require not only high resolution and high precision, but also space-saving installation, minimal impact on production flow, and easier system integration.
WHEC’s CIS line scan cameras combine compact design, distortion-free 1:1 imaging, and advanced lighting solutions to meet these demands and enable highly efficient inspection systems.
We have recently released a new product supporting 2400dpi resolution, a CoaXPress 2.0 interface, and scan speeds up to max. 69.1kHz (Mono), allowing compatibility with an even wider range of inspection requirements.
As manufacturers continue seeking both higher inspection accuracy and improved production efficiency, CIS line scan cameras are becoming an increasingly powerful solution. If you are facing challenges in your inspection process, please feel free to contact us.
Inquiry：WHEC
Choosing a CIS Line Scan Camera: 3 Critical Factors：https://www.w-hec.com/en/column/2580/ Wafer imaging demo video：https://youtu.be/FOHf-GytDXE?si=-4evDGBPlBHbsowb
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