In the field of semiconductor manufacturing, with the continuous improvement of chip integration and the continuous reduction of process nodes, traditional detection methods are no longer able to meet the precise identification needs of micro - or even nano level defects.Shortwave infrared cameraWith its strong penetrability, high contrast, and adaptability to complex environments, it is becoming a key tool in the field of semiconductor inspection, providing efficient solutions for core processes such as wafer bonding, laser cutting, and thermal imaging.
1、 Technical principle: "Optical microscope" that penetrates silicon materials
Short wave infrared cameras capture infrared radiation in the 900nm to 1700nm wavelength range for imaging, and their core advantage lies in the response characteristics of semiconductor materials to short wave infrared light
High transmittance of silicon material: Silicon has a transmittance of over 50% in the wavelength range of 1.2 μ m to 1.7 μ m. Short wave infrared light can penetrate the surface of the wafer and directly image the internal structure, while visible light is absorbed by the silicon substrate.
Defect scattering light imaging: Cracks, impurities, or poorly bonded areas inside the wafer can cause scattering of short wave infrared light. By capturing the difference in scattered light intensity through high-sensitivity InGaAs sensors, precise positioning of micrometer level defects can be achieved.
Breakthrough in Laser Hidden Cutting Imaging: In the wafer back cutting process, short wave infrared cameras can penetrate the coating layer, replacing traditional visible light cameras. By combining coaxial illumination and infrared light sources, real-time monitoring and quality evaluation of the laser cutting path can be achieved.
2、 Core application scenarios: from wafer inspection to thermal management
1. Wafer bonding defect detection
In 3D packaging and heterogeneous integration processes, minor defects in the wafer bonding layer may lead to chip failure. Short wave infrared cameras improve detection efficiency through the following methods:
Crack and impurity identification: The detection accuracy reaches 5 μ m, and nanoscale cracks or particle contamination at the bonding interface can be detected.
Bond strength evaluation: Quantify the uniformity and bonding strength of the bonding layer by analyzing the grayscale distribution of shortwave infrared images.
Yield improvement: After a semiconductor manufacturer applied this technology, the wafer bonding yield increased from 85% to 98%, saving over 10 million yuan in annual costs.
2. Laser Hidden Cutting Imaging and Edge Detection
Laser invisible cutting technology requires real-time monitoring of cutting depth and edge quality. The advantages of shortwave infrared cameras include:
Penetrating coating imaging: When AR film or metal layer is coated on the wafer surface, the cutting groove morphology can still be clearly displayed.
Edge burr detection: By analyzing the edge sharpness of shortwave infrared images, small burrs generated during the cutting process can be identified to avoid short circuits during packaging.
Cutting efficiency optimization: Combined with machine vision algorithms, real-time adjustment of laser power and cutting speed can shorten the cutting time of a single wafer by 30%.
3. Thermal imaging and fault diagnosis
The temperature distribution of semiconductor devices during operation directly reflects their reliability. The thermal imaging function of shortwave infrared cameras can achieve:
Overheated area positioning: Capture the temperature difference of 0.1 ℃ on the surface of the device and discover local hotspots of the power device.
Thermal resistance analysis: Quantify the thermal resistance between the chip and the heat dissipation substrate by comparing thermal imaging data under different operating conditions.
Life prediction: Establish a correlation model between temperature and failure time to warn potential faults in advance and extend the service life of devices.
3、 Technical Advantage: Triple Breakthrough in Accuracy, Efficiency, and Adaptability
High precision defect recognition:
Based on InGaAs focal plane array detectors, shortwave infrared cameras can achieve sub micron level spatial resolution. Combined with adaptive optics technology, they can overcome atmospheric interference and obtain high-resolution wafer defect images even under complex weather conditions.
Efficient non-contact detection:
The single detection time is shortened to the minute level, and there is no need to damage the sample, making it suitable for online detection in mass production lines. For example, in the wafer sorting process, short wave infrared cameras can be combined with high-speed sorting robotic arms to achieve detection and sorting speeds of over 10 pieces per second.
Environmental adaptability:
Shortwave infrared light is less affected by haze and smoke, has strong fog transmission ability, and can work stably in dust-free workshops or open environments. In addition, its night vision capability enables it to maintain high contrast imaging even in low light conditions, meeting 24-hour production needs.
4、 Industry Value: From Cost Control to Technological Innovation
Reduce manufacturing costs:
By early defect detection, we can prevent defective wafers from flowing into subsequent processes and reduce rework costs during packaging and testing stages. According to statistics, the application of shortwave infrared cameras can reduce the average manufacturing cost of semiconductor companies by 15% -20%.
Promote process optimization:
Real time feedback of defect data during wafer processing provides a basis for adjusting process parameters, accelerating the development and mass production of new processes. For example, in extreme ultraviolet lithography (EUV) technology, short wave infrared cameras can monitor the uniformity of photoresist coating and improve lithography accuracy.
Promote industrial upgrading:
With the rise of third-generation semiconductor materials such as silicon carbide and gallium nitride, short wave infrared cameras have broad prospects for application in wide bandgap semiconductor detection. Its high sensitivity and wide spectral response characteristics can meet the stringent requirements of new materials for detection equipment.
5、 Future outlook: Trends towards intelligence and integration
AI enabled defect classification:
Combined with deep learning algorithms, shortwave infrared cameras can automatically identify defect types such as cracks, impurities, and holes, and provide repair suggestions to further improve detection efficiency.
Multispectral Fusion Imaging:
By integrating multispectral sensors such as visible light, short wave infrared, and medium wave infrared, synchronous detection of surface and internal defects of wafers can be achieved, providing more comprehensive quality assessment data.
Miniaturization and portability:
With the integration of MEMS technology and CMOS technology, the volume and power consumption of shortwave infrared cameras will be further reduced, making them suitable for scenarios such as mobile detection devices and drone inspections.
Short wave infrared cameras, as a new tool in the field of semiconductor detection, are reshaping the industry landscape with their technological advantages. From wafer bonding to laser cutting, from thermal imaging to fault diagnosis, its application scenarios continue to expand, providing strong guarantees for high precision, high efficiency, and high reliability in semiconductor manufacturing. With the continuous innovation of technology and further cost reduction, shortwave infrared cameras are expected to play a key role in more fields, promoting the semiconductor industry to move towards a higher level.