Plasma colour in a sputtering chamber

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Discussion Overview

The discussion revolves around the information that can be inferred from the color of plasma in a sputtering chamber, particularly in the context of magnetron sputtering. Participants explore the relationship between plasma color and the elements or compounds being deposited, as well as the implications of impurities.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant inquires about the information derivable from the color of plasma, noting the presence of specific elements and impurities in the chamber.
  • Another participant mentions inductively-coupled plasma optical emission spectroscopy as a method for analyzing elements, suggesting the need for calibration with a standard, such as those from NIST.
  • A different participant expresses skepticism about the feasibility of conducting elemental analysis based solely on plasma color, particularly in reactive sputtering scenarios.
  • The original poster clarifies that their process involves normal magnetron sputtering and questions whether varying oxygen levels in the chamber can affect plasma color, providing examples of color changes associated with different film formations (green for Ti and light blue for TiO2).

Areas of Agreement / Disagreement

Participants exhibit a mix of viewpoints, with some suggesting potential methods for analysis while others question the validity of deriving elemental information from plasma color alone. The discussion remains unresolved regarding the extent to which plasma color can be used for elemental analysis.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about the relationship between plasma color and elemental composition, as well as the lack of specific databases or standards referenced for meaningful analysis.

teoporta
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Hi everyone,
my question is: what information can someone get by just looking at the colour of a plasma?
I the elements inside the chambers, together with some(few) common impurities.

Using the common spontaneous emission formula i can guess what transition emitted light with a particular frequency, but i don't have any database to make that data meaningful...

thank you
 
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teoporta said:
Hi everyone,
my question is: what information can someone get by just looking at the colour of a plasma?
I the elements inside the chambers, together with some(few) common impurities.

Using the common spontaneous emission formula i can guess what transition emitted light with a particular frequency, but i don't have any database to make that data meaningful...

thank you
Inductively-coupled plasma optical emission spectroscopy is a common method for analyzing elements in a material.

http://www.wfu.edu/chemistry/courses/jonesbt/334/icpreprint.pdf

One would need to calibrate one's system with a standard. One usually uses a standard obtained NIST.

There are other techniques for surface analysis:
http://www.chem.qmul.ac.uk/surfaces/scc/
 
Last edited by a moderator:
Actually, I'm not sure if you can make such analysis of the glow in a plasma used for sputtering.

In a reactive sputtering where the sputtered specie react with a gas that has been backfilled, you can tell the difference in the color between reactive and non-reactive, i.e. you detect a qualitative difference. However, whether you can make elemental analysis from the color, that I haven't seen done before.

Zz.
 
I see. Thank you for both your answers.
In my case it's normal magnetron sputtering.
Can a different amount of oxigen in the chamber change the colour of the plasma?
I'm sputtering using a Ti target:
If plasma is green it forms a Ti film, if it's light blue it forms TiO2 film...
 

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