The InGaAs EMMI has the same principle as the EMMI; the main difference lies in the Detectors: an InGaAs-CCD and a Si-CCD. While semiconductor processes advanced continuously and devices miniaturized their sizes, the operating voltage got lower and lower correspondingly. This lengthens the light wave generated when the electron and the electric-hole united, reaching the detecting limit of the traditional Si-CCD.
Since InGaAs-CCD has a higher sensitivity in detecting longer wavelengths, and due to the fact that Si-substrate tends to absorb light sources which cause interferences in back-side inspections, InGaAs EMMI has therefore become the most effective instrument for diagnosing device defects in advanced processes.
Conditions where light spots are detected:
Defects that produce light spots - Junction Leakage; Contact spiking; Hot electrons; Latch-Up; Gate oxide defects / Leakage(F-N current); Poly-silicon filaments; Substrate damage; Mechanical damage and Junction Avalanche; etc.
Light spots that existed originally - Saturated/ Active bipolar transistors; -Saturated MOS/Dynamic CMOS; Forward biased diodes/Reverse biased diodes (break down); etc.
Conditions where light spots cannot be detected:
Defects without light spots - Ohmic shorts and Metal shorts.
Light spots being blocked - Buried Junctions and Leakage sites under metals.
InGaAs EMMI has the following features:
Detects defects in a shorter period, 5 to 10 times shorter than EMMI.
Detects defects that EMMI is unable to detect (also detects micro current leakage and defects of advanced processes).
More advanced processes are more requiring for InGaAs EMMI to be able to detect defects.
It’s capable of detecting micro Metal Bridges and micro currents where EMMI is totally incapable of this.
Limited by lens rotation angles, a maximum of 4 probe manipulators (4 probe tips) can be installed on the stage. Maximum height of sample: 10 cm. Requires totally-dark-chamber operation without existence of light emitting devices. Not applicable when the product is heated.
|InGaAs & MCT & EMMI(CCD) COMPARE TABLE|| |