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Please note:  wafer level TXRF measurements are no longer available, details on TXRF Home Page.

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The minimum detection limit (MDL) is a convention that defines the sensitivity of our TXRF instrument.  When measuring the fluorescence spectra, the signal peak and background is defined as below.

Here, the red area corresponds to the signal while the blue area is background.  Since the noise of the background is considered to be a random process and can be modeled as a gaussian, the certainty of any peaks can be determined from statistics.  As a standard, a peak is considered detectable if it is 99% certain, which means the signal is 3 times greater than the standard deviation of the noise.  Since the standard deviation is simply the square root of the background, the minimum detection limit is determined by the equation below.

Note that C is the known concentration of the wafer being measured, and signal is the integrated intensity shown in red in the figure above.

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Last modified: January 26, 2007