Measuring the composition of downstream compostional byproducts is the only practical method to detect the health and endpoint of processes that don’t use plasmas. Even within plasma-assisted processes such as Etch, supporting Chamber Pre-Clean and qualification steps are performed without use of plasmas, preventing use of OES-based techniques to detect their endpoint. Pressures inside forelines leading from Implant, CVD, MOCVD and Etch process chambers aren’t compatible with conventional RGA or FT-IR sensors, making their use for endpoint detection impractical or impossible.

Without insight into these "No-plasma" processes which comprise up to 50-70% of overall process time, production personnel must rely on guesswork, on-going testing, and luck to predict when these critical supporting steps are complete.

Verionix sensors eliminate guesswork by providing real-time data that assures accurate endpoints without a need for process plasma. Ability to sense both process and supporting process endpoints with a single senosr systems eliminates the "No Plasma: No Endpoint Detection"  dilemma, reducing scrap and increasing tool productivity.
 

Problem

  • A SiN Etch process needs to be monitored in real-time to assure proper material removal and prevent damage to the underlying circuit structure.
  • The endpoint of this process can't be detected using conventional OES systems because no plasma is utilized.
  • Rate of material removal is very low at 10 nm/minute, demanding superior sensitivity to the gaseous byproducts resulting from this etch step.

Process Environment and Setup

  • Endpoint signals to be detected in a multigas gas Argon-Freon-Chlorine process environment.
  • < 200 mTorr vacuum level.
  • Verionix Vx-2000 series sensor mounted in chamber foreline downstream of Etch chamber.

Critical Verionix Data

  • Real-time data representing the level of SiN etch byproducts detected in the mixed gas environment is reported to supervisory control system.
  • Process endpoint is calculated using proprietary algorithms by the supervisory controller.

Results

  • Previously uncontrolled and undetectable endpoint of "no plasma" etch process is implemented.
  • Damage to product as result of etch process better controlled.
  • Tool productivity increased.

 

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