Test and Measurement
Above: Figure 8, Above right: Figure 9,
Issue III 2009
Right: Table 1
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This example shows that the level and time constant of the
RTS noise and the number of peaks in the histogram vary in
conjunction with changes in the gate voltage.
As this result illustrates, it is necessary to measure RTS
noise under a variety of combinations of bias conditions,
current ranges and sampling rates. In this way, the distribution of the RTS noise across the wafer it is possible to
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measurement data can yield valuable insights into the evaluate the distribution of defect densities that correspond
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distribution and the time constants of the boundary traps. directly to the operation of the device.
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Distribution on Wafer Conclusion
29
Since the size of the MOSFETs is very small, depending on RTS noise analysis at the readout amplifier of each pixel of
the distribution and frequency of defect traps on the wafer modern, high resolution CMOS image sensors is essential to
some devices will not show any RTS noise while other devices minimize random pixel noise in a captured image.
will show significant RTS noise. The B1500A’s WGFMU module is a self-contained,
From the previous discussion, it is clear that it is off-the-shelf measurement solution for MOSFET RTS noise
necessary to measure multiple devices across a wafer in order measurement, making it the ideal solution for the accurate
to observe RTS noise. Conversely, by evaluating the spatial and repeatable analysis of RTS noise in CMOS image sensors.
Key specifications of the B1500A’s WGFMU module
Voltage Force
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Measurement resolution
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RTS data analysis software
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Output Range: 0.014 % of range
*2
This software can perform time
+/-5 V domain and frequency domain
0 V ~+10 V
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Noise floor analysis of the drain current
-10 V ~ 0 V 0.2 % of range
*3
measured by the B1500A’s WGFMU
module and automatically display
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Noise floor:
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Sampling interval extracted parameters.
Less than 0.1 mV (rms)
*1
5 ns 10 ns to 1 s Variable
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Visualized time domain data and
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Current Measurement
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Hardware averaging digitized data
Measurement range: 10 ns to 20 ms Variable
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Power distribution
+/- 10 mA fixed
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Histogram of the level and
+/- 1 mA fixed
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Measurement memory depth appearance
+/- 100 box2 A fixed About 4 million data points
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Histogram of the capture and
+/- 10 box2 A fixed per channel
*4
emission time constants and their
+/- 1 box2 A fixed ratio
*1 Theoretical value (100 ns to 1 ms)
*2 Display resolution. Can vary at most 5% based on the result of calibration.
*3 Supplemental information. Effective value, without averaging at 0 V into an open load
*4 Typical value
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