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Semiconductor wafer visual inspection system

Semiconductor wafer visual inspection system Product appearance

RAYSENS is a macro inspection system that can detect defects on wafers with high speed and high sensitivity using optical technology that captures slight changes in light. It can inspect both bare wafers and patterned wafers, and uses the optimum optical system and detection algorithm for each defect target to detect defects quickly and with high sensitivity. The high throughput of the system enables to promote automation of total inspection instead of visual inspection by conventional sampling.

The market for wide bandgap (WBG) devices is expected to grow as high-frequency (RF) devices for fifth-generation (5G) communications and data centers (DC), power devices for electric vehicles and other next-generation vehicles (xEV), and optical devices for LEDs and laser diodes (LDs). Also, there is  the increasing demand for semiconductors and other MEMS.

In response to the increased demand for the above-mentioned semiconductors, RAYSENS provides a wide variety of wafer inspection and in-process inspection services, not only for conventional silicon wafers (Si), but also for compound semiconductors (SiC, GaN, GaAs, InP, etc.), oxide semiconductors, epitaxial wafers, etc. RAYSENS provides a wide variety of wafer inspection services, including visual inspection, in-process inspection, and in-situ inspection, for compound wafers. We support you. Japanese web page


1. Ultra-low noise macro-optical sensor developed exclusively for this system, and dedicated illumination to detect minute changes in various wafer surfaces with high sensitivity

2. High throughput by dedicated optics, integrated software and highly efficient transfer loader

3. Wide range of inspection from transparent (semi-transparent) wafers such as compound semiconductors to non-transparent wafers such as silicon wafers
Both patterned and bare wafers can be inspected.

4. Dedicated integrated application software enables seamless operation from machine control to image acquisition and judgment

5. Non-contact wafer front and back handling and inspection for final visual inspection, minimizing problems such as foreign matter adhering to the backside of the wafer

*We can also perform a preliminary evaluation using a demo machine with workpieces prepared by the customer.
Please contact us for more information.


Field of use

Field of use


Inspection target

Inspection target


RAYSENS Principle of Detecting Defect

RAYSENS Principle of Detecting Defect


High level of traceability with RAYSENS

All wafer images and detailed data are recorded and accessible at any time.
・Output and storage of image data and detailed inspection information for each wafer
・View the history of wafer inspection results for all OK and NG products at any time
・Output and storage of barcode, wafer ID (*1) and other information reflected in inspection data
・Enables effective use of inspection data, such as analysis of inspection data, manufacturing recipes, and reflection in manufacturing processes
High level of traceability with RAYSENS

Product Specifications

Configuration Type

3 cassettes Configuration Equipment appearance
3 cassettes Configuration
Equipment appearance
15 cassettes Configuration Equipment appearance
15 cassettes Configuration
Equipment appearance


Item Selectable main specifications
Wafer size ~ 200mm (Open cassette compatible)
Sensitivity 0.3um(PSL on Si wafer)
Through put Max.20-25sec/wafer
lighting LED uniform line lighting
High brightness fiber lighting
Wafer transfer method Double arm transfer
Application Integrated optical control, integrated mechanical control, image scanning
Image processing function dedicated to macro inspection,
Defect detection judgment function
Number of cassette port Min1 ~ Max 15
The others Ionizer
HEPA Filter

Sample evaluation

TED Engineering Center(Demo / Validation Facility)

Evaluating for customer’s wafer can be performed by Our Demo Equipment

For customers who would like to see the surface condition and defects using the macro optical inspection system, we can borrow a sample of the target workpiece and conduct a preliminary evaluation using the demonstration machine. Please contact us for further information.


TED Engineering Center(Demo / Validation Facility)



What is Macro Optics?
Macro-optics is an optical technology that irradiates light onto an object with a dedicated optical device and captures slight changes in the light from the reflected light information. Compared with conventional visual inspection and microscopic inspection, macro-optics enables inspection of the entire surface of a workpiece at the micron and submicron order in a shorter time than conventional visual inspection and microscopic inspection, and thus enables stable 100% inspection.

What is the Photoluminescence (PL) method?
The photoluminescence (PL) method is a technique for observing the light emitted when excited electrons return to their ground state by irradiating a material with light, and obtaining a variety of information from the resulting emission spectrum. Since PL is easily affected by impurities and defects in the material, the PL spectroscopy can be used to observe crystal defects in compound semiconductors (SiC, GaN, etc.) without contact and nondestructively by analyzing the emitted light.

What is confocal microscopy?
Confocal microscope is a microscope that uses an objective lens to focus light from a point light source onto a sample, and then reconfocalizes the reflected light or fluorescence from the sample through the same objective lens onto a point detector placed at an optically conjugate position. This method enables us to observe an object more clearly than conventional microscopes and to obtain detailed information such as the shape of microscopic surface defects such as semiconductors.

What is a Scanning Electron Microscope (SEM)?
A scanning electron microscope (SEM) uses electrons to observe a magnified image of a sample. Because electrons have a shorter wavelength than light, it is possible to see much smaller objects than with a conventional optical microscope. Since electrons can observe structures as small as several nanometers and produce images with a deep depth of focus, SEM can magnify the structure of a sample surface that is highly uneven, allowing us to observe three-dimensional images in the same way that we see things with the naked eye.

What is a power semiconductor?
Power semiconductors are semiconductor devices used as switches and rectifiers in power electronics (such as switching power supplies). They are also called power devices, and when used in integrated circuits, they are also called power ICs.
For high-current/high-voltage applications, power semiconductors are partially replacing silicon with wide bandgap semiconductors.

What are wide bandgap semiconductors?
Wide bandgap semiconductors (also called WBG semiconductors or WBGS) are semiconductor materials with a larger bandgap than conventional semiconductors. They allow devices to operate at much higher voltages, frequencies, and temperatures than conventional semiconductor materials such as silicon and gallium arsenide.
Since silicon has a band gap of 1.12 eV, it is often called wide-gap when it has a band gap of 2.2 eV or more, which is about twice the band gap of silicon.
Wide-gap devices are considered to be promising next-generation devices for high-efficiency power supply components required for railroads, electric vehicles, and other applications. SiC, GaN, and diamond are representative wide bandgap semiconductors.

What is SiC (silicon carbide)?
SiC (silicon carbide) is currently the most promising wide-gap semiconductor for next-generation power semiconductor devices.
SiC chips have higher power density than silicon power devices, can handle higher temperatures than 150°C, the limiting temperature for silicon, and can be made smaller than Si. Many automakers are planning to incorporate SiC into their power electronic devices.

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Semiconductor wafer visual inspection system Product appearance
Semiconductor wafer visual inspection system Product appearance

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