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Higher resolution cameras combined with high speeds allow for improvements in accuracy required by manufacturers of semiconductor wafer inspection and metrology equipment.
While companies like Samsung and Apple are responding to and feeding the consumers’ demands for more and better smartphones and tablets, the semiconductor manufacturing industry has grown by focusing on supporting them.
To increase the capabilities of smartphones, more powerful processors are required with higher density chips.
This presents new challenges for manufactures of inspection and metrology equipment. With semiconductor wafer manufacturing, smaller features must be detected without compromises in throughput to help sustain or improve yield.
Detect Smaller Features
The push into the 22 and 20 nm technology node results in many changes. There has been an on-going evolution in front-end semiconductor manufacturing to move from in-line inspection rather than off-line, destructive analysis whenever possible. This requires a variety of inspection and metrology equipment with high quality and stable visible, Infra Red (IR), or Ultra Violet (UV) sensitive cameras.
Bare Wafer Metrology
Before any transistor is laid down, the incoming silicon wafer must be analyzed for flatness and defects. From this inspection, wafers can be classified to allow the best wafers to be used for the smallest technology node. Typically measurement techniques such as interferometry are used for this. Extremely stable cameras with low noise are needed for accurate measurements. More on this later…
Overlay Metrology
As the features become smaller, the need to align the layers precisely is greater. There are different techniques used for this, but all require a high quality camera. As with all measurements, high quality means that the variations in the camera and the images are smaller than the variations of what you are trying to measure in the production line so you are not measuring within the noise of the camera.
Micro Defect Inspection
The defects and particles that are disruptive are even smaller with the smaller features and devices. Higher resolution cameras with better spatial resolution can improve capabilities for these inspection systems.
CD Metrology
With the latest technology nodes, there are even tighter dimensions to measure accurately. Again the implementation of higher resolution cameras can improve capabilities.
Increase wafer throughput
For all of the techniques mentioned above, precision and accuracy must be increased while maintaining or increasing throughput.
The challenge for camera manufacturers is to preserve image quality at the fastest frame speeds, but it is possible. Supporting camera technology/functionality such as burst mode, CoaXPress and region of interest (ROI) can further increase speeds.
Improve yield with reliable & stable performance
The goals with better metrology are to detect problems and defects in order to correct for them to prevent yield problems or make process improvements to increase yield. Even a 0.1% improvement in yield can mean an increase in profitability of millions of dollars.
Cameras with consistent performance reduce the metrology variability and serves to betterdetermine the process variation. This reduces process deviations, allowing root cause analysis to take corrective action. Also, as mentioned before, the cameras need to be high quality where the variations from image to image in the camera are smaller than what is being measured.
High-resolution cameras combined with high speeds that make full use of select image sensors provide the images required for inspection and metrology of the latest generation devices that go inside your latest smartphones and tablets.
