Influence of Voltage, Pulselength and Presence of a Reverse Polarized Pulse on an Argon–Gold Plasma during a High-Power Impulse Magnetron Sputtering Process

Round 1

Reviewer 1 Report (Previous Reviewer 2)

Review on Influence of various parameters on an argon-gold-plasma during a High-power impulse magnetron sputtering process

I have completed my review of manuscript Plasma-2574418, entitled, “Influence of various parameters on an argon-gold-plasma during a High-power impulse magnetron sputtering process.”

This study focuses on optimizing the deposition of gold through High-power Impulse Magnetron Sputtering (HIPIMS), targeting suitable process parameters. The effects of voltage, pulse length, and the kick-pulse on argon-gold plasma during bipolar HIPIMS deposition are examined using Optical Emission Spectroscopy (OES) and oscilloscope analysis. Notably, higher voltages correlate with increased presence of excited gold atoms and influence the plasma, while pulse length primarily affects argon ionization. Importantly, the presence of ionized and excited argon, as well as gold, is analyzed with respect to the evolving discharge current. The study identifies the preference for short pulses and high voltages for gold deposition. These findings offer valuable insights for enhancing the direct metallization of polyimide substrates and guiding future research in optimizing deposition processes using plasma-based techniques.

The subject and findings of this article are interesting and useful. Before making a positive decision, I have some concerns and comments about the present form of the manuscript that must be addressed first.

Comments for authors

Comment 1: To improve the abstract, it is suggested to add a statement highlighting the significance and novelty of the work, as it is not currently evident from the abstract. Additionally, it would be beneficial to end the abstract with a concluding statement or possible application to provide a clear summary of the study.

Comment 2: The current title appears not so intresting. I recommend revising it to convey more specific and closely aligned information related to your study.

Comment 3: Could you elaborate on the underlying mechanisms responsible for the strong increase in excited gold atom presence in plasma with higher voltages? How do these mechanisms relate to the deposition process and the resulting gold layers? Explain in the manuscript.

Comment 4: In pulse length analysis, authors mentioned a pronounced rarefaction during HIPIMS deposition of gold. How does this rarefaction impact the overall deposition process, and what implications does it have for optimizing the process parameters?

Comment 5: Authors mentioned that longer pulses do not lead to measurable ionization of gold. Could you discuss the reasons behind this behavior and its potential significance for the ionization dynamics in the HIPIMS deposition process?

Comment 6: Authors mentioned the preference for very short pulses and high voltages for gold deposition. Could you discuss the trade-offs and considerations that guide this preference, especially in terms of layer quality, deposition rate, and power efficiency?

Minor comments

Comment 7: I recommend consolidating Figure 7 into Figure 1, creating a combined illustration. As Figure 7 currently appears as a photograph without conveying meaningful information to readers.

Comment 8: The paper contains errors and typos that make it difficult to understand and distort its intended meaning. I encourage authors to reread carefully and fix any grammatical errors.

The paper contains errors and typos that make it difficult to understand and distort its intended meaning. I encourage authors to reread carefully and fix any grammatical errors.

Author Response

Dear Reviewer, 

Thank you for your comments. 

Regards

Jürgen Guljakow

Author Response File: Author Response.pdf

Reviewer 2 Report (New Reviewer)

The reviewer has the following comments: 1) it is necessary to sign the lines that were measured on the emission spectra, 2) it is unacceptable to use the links in the "Conclusions" section, 3) it is desirable to move the formulas to the "Methods" section, 4) Remove the meaningless drawing with the plasma image.

Author Response

Dear Reviewer, 

Thank you for your comments. 

Regards

Jürgen Guljakow

Author Response File: Author Response.docx

Reviewer 3 Report (New Reviewer)

Dear Authors

The article need to be improve based on the related article. The article reveals the study on various parameters on an argon-gold-plasma during high power impulse magnetron sputtering process.  Authors need to compare other plasma process and unique in argon plasma. whats the aim of combine argon with gold in plasma system?

Author need to clarify those details.

Author Response

Dear Reviewer, 

Thank you for your comments. 

Regards

Jürgen Guljakow

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report (Previous Reviewer 2)

I recommend accepting the paper in its present form.

Reviewer 3 Report (New Reviewer)

Author has performed necessary correction in the article and has improved now.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

This paper describes an influence of amplitude and pulse width of the applied pulsed voltage in HiPIMS system on plasma property based on analysis of spectrum of the light emission from the plasma. I agree that the spectrum of light emission from the plasma includes important information of the plasma property such as electron temperature, ion species, etc. However, the submitted paper missed the important information such as plasma density, electron temperature, ion flux, ion densities, power density, and those temporal-special distribution. As the experimental results, the raw spectra data and each peak intensity are described without combination of analysis such as CR-modeling, or global modeling. In my opinion, it is difficult for recommendation to publish on the journal because the paper does not include useful information for the readers in same research field.

Author Response

Dear Reviewer, 

Thank you for your Review. 

Regards

Jürgen Guljakow

Author Response File: Author Response.pdf

Reviewer 2 Report

Review on Influence of various parameters on an argon-gold-plasma during a HIPIMS process

I have completed my review of manuscript Plasma-2324884, entitled, “Influence of various parameters on an argon-gold-plasma during a HIPIMS process.”

The influence of voltage, pulse length, and the kick-pulse on an argon-gold plasma during a bipolar HIPIMS deposition process was analyzed via optical emission spectroscopy (OES). According to the results, the influence of the voltage on the plasma was more pronounced, than the influence of the pulse width. While the brightness of several Au I lines increases up to 13-fold for increasing voltages, only a less-than-linear increase in brightness with time could be identified for changes in pulse length.

The subject and findings of this article are interesting and useful. Before making a positive decision, I have some concerns and comments about the present form of the manuscript that must be addressed first. Follow each comment and revise accordingly.

Comments for authors

Comment 1: To improve the abstract, it is suggested to add a statement highlighting the significance and novelty of the work, as it is not currently evident from the abstract. Additionally, it would be beneficial to end the abstract with a concluding statement to provide a clear summary of the study.

Comment 2: As the field of plasma is broad, the background information provided by the authors may be insufficient. It would be informative for readers if the authors included information regarding nonthermal plasma and its applications in the background section. The following recent article could be a useful resource to incorporate into the background information. [Review on the Biomedical and Environmental Applications of Nonthermal Plasma. Catalysts 2023, 13.]

Comment 3: In line 66, what is “occurring current”? Does it mean discharge current?

Comment 4: It would be helpful if the author could explain the observed linear increase in peak-current density with increasing voltage in Figure 2. Specifically, it would be beneficial to clarify the reason for this linear increase during the main pulse, as it appears to be opposite during the kick pulse after approximately 25 µs.

Comment 5: Figure 6 is very confusing, the figure is about current density varying the time as shown 20, 50, and 100 μs, while the x-axis also shows time 0 to 200 µs. What is the x-axis time and selected variable time?

Comment 6: The figures are not well explained which makes it difficult to comprehend. I recommend explaining the figure legend in more detail so readers can easily understand the figures and their intended meanings.

Comment 7: The conclusion section requires revision to provide a clear explanation of the key findings. Additionally, it would be beneficial to discuss the potential applications of these findings.

Comment 8: The paper contains errors and typos that make it difficult to understand and distort its intended meaning. I encourage authors to reread carefully and fix any grammatical errors.

Author Response

Dear Reviewer, 

Thank you for your remarks.

Regards

Jürgen Guljakow

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

I am sending the review report for resubmitted Manuscript ID plasma-2324884, entitled “Influence of various parameters on an argon-gold-plasma during a HIPIMS process”, submitted by Jürgen Guljakow and Walter Lang.
This paper describes an influence of amplitude and pulse width of the applied pulsed voltage in HiPIMS system on plasma property based on analysis of spectrum of the light emission from the plasma.
I checked the resubmitted paper and the response from the author. I understood the purpose of the study and the method for the observation of Au target HiPIMS combined with kicker pulse, i.e. bipolar pulse system. I agree that the paper includes novelty such as Au sputtering for various high-voltage pulse conditions, and includes useful information such as influence of kicker pulse on flux of the sputtered Au particles and current density of the HiPIMS plasma.
However, the almost researchers maybe expect the information of flux (or dose) of the sputtered Au particles, especially Au ions, and Ar ions, which is main player for sputtering the Au target. The submitted paper includes only direct spectrum measured by OMA observation.
The all data are still only qualitative information for the flux of the sputtered particles and for the HiPIMS plasma. In my opinion, this paper should be modified for including quantitative discussion for the flux of sputtered particle and for generated plasma via bipolar pulse system.

Sincerely Yours,

Reviewer 2 Report

I appreciate the authors have addressed on of my comments and concerns in the revised version. I recommend accepting the paper for publication.