Chamber-Chamber Matching

Case Study

Company:

Boston Scientific is a global leader in the development, manufacturing, and distribution of medical devices designed to improve patient health and enhance quality of life.

Challenge:

A medical device manufacturer developed a production line for stents, which included a plasma processing step. When the production line needed to be expanded, the plasma tool previously used was no longer available on the market, requiring the development of a new tool. Due to the medical aspect of this product, it was critical that the new plasma chamber be validated to run the exact same process, ensuring consistent product treatment and quality.

Solution:

Process transfer and process verification were carried out using a suite of in-situ plasma diagnostics to ensure that the fundamental plasma parameters were were consistent between the old and new machines. The Semion RFEA and a Flexible Langmuir Probe were the diagnostics tools for this process.

Process:

First, the old chamber was fully characterized. Measuring 3 meters in length with a 1 x 1 meter cross-section, the chamber featured several shelves that held the product. The Semion and Langmuir probes were positioned at different locations on each shelf to map the following plasma parameters:

  • Ion energy distribution
  • Ion flux
  • Plasma density
  • Electron temperature
  • Plasma potential
Figure 4 Schematic of a “shelf” plasma chamber of 3m x 1m x 1m size. The placement of Langmuir probe and Semion RFEA diagnostic tools are also shown.
Process:

A 2D map for each shelf was created for each parameter. The standard plasma process recipe was executed, along with slight variations in power, pressure, and gas flow.

Figure 5 Representative contour plot of the spatial variation of the electron density. Black dots show points data was taken.

Next, this process was replicated in the new tool, with power and pressure adjustments made to match the fundamental plasma parameters across the shelves.
Both plasma tools were equipped with an Octiv Poly VI probe positioned after the matching box to monitor the power delivered to the plasma and the plasma impedance during the production plasma recipe. Data from the Octiv was collected while the tool operated within specifications (100% product yield) and was used to track process drift, helping to determine when tool cleans, or repairs were necessary.

Back To Top