Practice Test Geeks(CCT) Certified Casper Technician Practice Test
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System Operation & Monitoring Flashcards

7 cards from real CCT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. During Casper system operation, the process recipe calls for a pressure ramp from 5 mTorr to 50 mTorr over 30 seconds. The throttle valve controller fails to track. What is the MOST likely result if the process continues?

    Answer: Process deviation leading to out-of-spec results and possible wafer damage

    Uncontrolled pressure deviations alter plasma density and etch chemistry, leading to out-of-spec process results and potential wafer damage.

  2. A Casper system's remote I/O module stops communicating during a run. Which system function is MOST at risk of uncontrolled behavior?

    Answer: Digital valve states and interlock feedback signals

    Remote I/O modules control digital valve outputs and read interlock inputs; loss of communication can leave valves in undefined states and disable safety feedback.

  3. When comparing Casper system idle base pressure to the qualification baseline, a 40% increase is observed. The FIRST diagnostic step should be:

    Answer: Perform a residual gas analysis (RGA) scan to identify contamination sources

    An RGA scan identifies which gas species are elevated, distinguishing between leaks (atmospheric gases) and outgassing (water vapor, process residues).

  4. A Casper system operator reports that wafer temperature uniformity has degraded from ±2°C to ±8°C across the wafer. Which component is MOST likely responsible?

    Answer: ESC zone-to-zone helium backside pressure imbalance

    Helium backside gas pressure on the ESC controls wafer-to-chuck heat transfer; imbalance between zones causes non-uniform wafer temperature.

  5. In a Casper monitoring system, OES (Optical Emission Spectroscopy) data shows a sudden increase in the Si emission line intensity mid-process. This MOST likely indicates:

    Answer: A process endpoint has been reached and silicon is being exposed

    A rising Si emission signal during etch typically signals that the underlying silicon layer is being exposed, often used as an end-point detection signal.

  6. A Casper technician records that mean time between assisted maintenance (MTBAM) for a specific subsystem has decreased from 90 days to 45 days over six months. This metric trend indicates:

    Answer: Degraded reliability requiring root cause analysis and corrective action

    A 50% reduction in MTBAM means failures are occurring twice as often, indicating a reliability problem that requires root cause investigation.

  7. During Casper system monitoring, an unexpected spike in chamber wall temperature is detected while RF power remains stable. The MOST probable cause is:

    Answer: A plasma mode transition or arc event within the chamber

    Plasma arcing or mode transitions release localized energy bursts that produce sudden wall temperature spikes without changes to the commanded RF power level.