In-Situ Repair Plasma-Induced Damage and Cap Dielectric Barrier for Porous Low-Dielectric-Constant Materials by HMDS Plasma Treatment
Round 1
Reviewer 1 Report
Comments to the manuscript coatings-1100761: In-situ Repair Plasma-induced Damage and Cap Dielectric Barrier for Porous low-Dielectric-Constant Materials by HMDS Plasma Treatment.
The manuscript impressively underlines the possibility of HDMS application in repairing of O2-plasma-induced defects in wafers forming a coating layer with low-k values as barrier skipping problems of Cu migration. This technique is of high interest for industrial application. Experimental data underline the hypotheses of the paper and are presented in a concise way. The paper is well structured and of high scientific and lingual quality. Hence, I recommend publication after some minor corrections. They are as followed:
- Damages in the wafer material by plasma based etching were concisely presented. Beside the actual repair mechanism, it might be very helpful to present potential applications of plasma processes in a short way to underline the flexibility of this technology, i.e. beside coatings (DBD) plasma are used for treatment of other surfaces, VOC abatement, disinfection, odor removal… Some references, which might be very helpful in this context are:
- Surfaces:
- https://dx.doi.org/10.1016/S0168-583X(03)00644-X
- https://doi.org/10.1016/j.jfoodeng.2014.12.017
- VOC and odor abatement
- https://dx.doi.org/10.1016/j.jece.2018.03.012
- https://dx.doi.org/10.1016/j.jiec.2018.03.005
- Disinfection
- https://dx.doi.org/10.1109/PLASMA.2004.1339779
- https://dx.doi.org/10.1371/journal.pone.0180183
- Gas reforming/transformation
- https://dx.doi.org/10.3390/su12218981
- Line 195: Please give an explanation why the results as shown in Figure 6 was independent of the contact time, i.e. why was there no enhanced repair mechanisms in case of longer exposure times to HDMS and plasma. In this context, why is the result at 30 s poorer than at 10 s even though they are nearly the same.
- Figure 7: As ten samples were tested per data point it would be helpful to show error bars in the figure to get an impression about variation of test results.
- Line 211-212: According to figure 7 please further clarify the effect of reduced breakdown fields, especially to the fact that the k-value of HDMS vapor itself is higher than in case of 30 s of deposition, i.e. why is the value lower at 30 s exposure and formation of a stable layer compared to the vapor itself?
- Surfaces:
Author Response
The manuscript impressively underlines the possibility of HDMS application in repairing of O2-plasma-induced defects in wafers forming a coating layer with low-k values as barrier skipping problems of Cu migration. This technique is of high interest for industrial application. Experimental data underline the hypotheses of the paper and are presented in a concise way. The paper is well structured and of high scientific and lingual quality. Hence, I recommend publication after some minor corrections. They are as followed:
- Damages in the wafer material by plasma based etching were concisely presented. Beside the actual repair mechanism, it might be very helpful to present potential applications of plasma processes in a short way to underline the flexibility of this technology, i.e. beside coatings (DBD) plasma are used for treatment of other surfaces, VOC abatement, disinfection, odor removal… Some references, which might be very helpful in this context are:
- Surfaces:
- https://dx.doi.org/10.1016/S0168-583X(03)00644-X
- https://doi.org/10.1016/j.jfoodeng.2014.12.017
- VOC and odor abatement
- https://dx.doi.org/10.1016/j.jece.2018.03.012
- https://dx.doi.org/10.1016/j.jiec.2018.03.005
- Disinfection
- https://dx.doi.org/10.1109/PLASMA.2004.1339779
- https://dx.doi.org/10.1371/journal.pone.0180183
- Gas reforming/transformation
- https://dx.doi.org/10.3390/su12218981
- [Reply] Thanks for reviewer’s suggestion. This technology should be applied on many applications. But I think that it is not suitable to add these information on this manuscript.
- Line 195: Please give an explanation why the results as shown in Figure 6 was independent of the contact time, i.e. why was there no enhanced repair mechanisms in case of longer exposure times to HDMS and plasma. In this context, why is the result at 30 s poorer than at 10 s even though they are nearly the same.
- [Reply] J-V plot in Fig.6 can give two outputs: leakage current and breakdown field. From the perspective of leakage current and breakdown field, 10 s HMDS plasma treatment had the best repair effect. HMDS plasma 30s forms a thick dielectric with lower breakdown field, and results in higher plasma damage.
- Figure 7: As ten samples were tested per data point it would be helpful to show error bars in the figure to get an impression about variation of test results.
- [Reply] We had added error bars in Fig.7 in the revised manuscript.
- Line 211-212: According to figure 7 please further clarify the effect of reduced breakdown fields, especially to the fact that the k-value of HDMS vapor itself is higher than in case of 30 s of deposition, i.e. why is the value lower at 30 s exposure and formation of a stable layer compared to the vapor itself?
- [Reply] A thick dielectric was formed by a 30 s HMDS plasma treatment. During plasma irradiation for a long time, serious plasma damage on the underlying low-k material, resulting in a lower breakdown field. We had re-written the paragraph about Fig. 7.
- Surfaces:
Reviewer 2 Report
A substantial advancement has been achieved during last decade on the realization of porous SiOCH thin films by chemical vapor deposition approaches. However, this research sector still provides relevant questions to be answered. Within a current manuscript a scientific community can find a hint how to improve electrical characteristics, dielectric breakdown reliability, and Cu barrier capability of the low-dielectric-constant (low-k) porous SiOCH thin layer. By means of Hexamethyldisilazane (HMDS) plasma processing a reparation effect is observed. One of the main of recovering signatures stands behind of hydrophobic Si-CH3 bonds reappearing in the oxygen plasma damaged film. Another finding suggests the Si-OHBond removal after (HMDS) plasma treatment.
In general, a manuscript is presented well, containing some original data with a reasonable scientific meaning. Nevertheless, some remarks should be considered before publishing
1) Page 2, line 51:
Please define an abbreviation “BEOL”, as it is mentioned first time in the text
2) Page 2, line 61:
Fig.1 b please define an abbreviation “SAMs”. Its definition appears first when discussing Fig.2 on page 3, line 111
3) Page 3, line 86
What was the operating pressure when plasma ignited? Was the sample thermally damaged (melted) after longer plasma treatment time, namely HMDS at 30s?
4) Page 6, line 156
Why the curve treaded with HMDS at 30 seconds is not presented in Fig.4? Please insert it ad discuss it as well as others.
5) Page 9, line 234:
A small suggestion to rewrite…… “…were sealed by precursor molecules during short-time HMDS vapor and plasma processing”.
6) Page 10, line 237:
A small suggestion to the figure. When presenting fitting parameter γ, please, do not provide too many digits after comma. Also use the same number of digits in each experimental curve. For instance, the oxygen treated sample has 3 signs after comma, while others have 4. Try to be consequent. Regarding Fig 8 it is fairly enough to write γ=0.66, γ=1.32, γ=1.76 and γ=2.38 with an uncertainty ±0.01 (as an example)
7) Page 10, line 258
“Removal off” instead “removal of”
8) A general suggestion to figures.
Try to improve figures for better visualization. It is much simple to follow the results presented like in Fig.8 (colored) that of, for instance displayed in Fig.9.
Author Response
A substantial advancement has been achieved during last decade on the realization of porous SiOCH thin films by chemical vapor deposition approaches. However, this research sector still provides relevant questions to be answered. Within a current manuscript a scientific community can find a hint how to improve electrical characteristics, dielectric breakdown reliability, and Cu barrier capability of the low-dielectric-constant (low-k) porous SiOCH thin layer. By means of Hexamethyldisilazane (HMDS) plasma processing a reparation effect is observed. One of the main of recovering signatures stands behind of hydrophobic Si-CH3 bonds reappearing in the oxygen plasma damaged film. Another finding suggests the Si-OHBond removal after (HMDS) plasma treatment.
In general, a manuscript is presented well, containing some original data with a reasonable scientific meaning. Nevertheless, some remarks should be considered before publishing
1) Page 2, line 51:
Please define an abbreviation “BEOL”, as it is mentioned first time in the text
[Reply] We had defined an abbreviation “BEOL” in the revised manuscript.
2) Page 2, line 61:
Fig.1 b please define an abbreviation “SAMs”. Its definition appears first when discussing Fig.2 on page 3, line 111
[Reply] We had defined an abbreviation “SAMs” in the revised manuscript.
3) Page 3, line 86
What was the operating pressure when plasma ignited? Was the sample thermally damaged (melted) after longer plasma treatment time, namely HMDS at 30s?
[Reply] We added the operating pressure when plasma ignited in the revised manuscript. From our and others results, plasma indeed damage the low-k film depending on the used plasma gas, power, time, etc. Therefore, HMDS plasma 30s forms a thick dielectric with lower breakdown field, and results in higher plasma damage.
4) Page 6, line 156
Why the curve treaded with HMDS at 30 seconds is not presented in Fig.4? Please insert it ad discuss it as well as others.
[Reply] Sorry, due to poor performance for HMDS plasma treatment 30 s , we did not measure this condition for Fig. 4.
5) Page 9, line 234:
A small suggestion to rewrite…… “…were sealed by precursor molecules during short-time HMDS vapor and plasma processing”.
[Reply] Thanks for reviewer’s suggestion! We had rewritten this sentence in the revised manuscript.
6) Page 10, line 237:
A small suggestion to the figure. When presenting fitting parameter γ, please, do not provide too many digits after comma. Also use the same number of digits in each experimental curve. For instance, the oxygen treated sample has 3 signs after comma, while others have 4. Try to be consequent. Regarding Fig 8 it is fairly enough to write γ=0.66, γ=1.32, γ=1.76 and γ=2.38 with an uncertainty ±0.01 (as an example)
[Reply] Fig.8 had been revised based on reviewer’s suggestion.
7) Page 10, line 258
“Removal off” instead “removal of”
[Reply] This typo error had been corrected.
8) A general suggestion to figures.
Try to improve figures for better visualization. It is much simple to follow the results presented like in Fig.8 (colored) that of, for instance displayed in Fig.9.
[Reply] All figures had been re-plotted for better visualization.
Reviewer 3 Report
The paper is very well articulated, providing various characterizations and application of such fabrication method will indeed improves interconnects used in MEMS based devices. However, the authors need to address the following comments to improve the paper and provide more clarity. I would encourage the authors to resubmit and improve the paper based on the comments.
- Page 1, line 35-37 in the Introduction section, the authors need to provide reference for the phenomenon.
- In the introduction section please clarify why SiOCH film was chosen. What are the advantages over other available films in use?
- Page 2, line 77 in the Experimental section, please rewrite the sentence and give a description in a couple lines about the process. Please refrain from using the term “elsewhere”.
- Page 3, line 112 in the Results and Discussion section, the authors can rewrite the sentence as “It was observed that as the RF power was turned on for HDMS plasma treatment, the thickness increased with increasing plasma treatment time”.
- Page 3, line 113-116 in the Results and Discussion section, the authors must provide a reference for the phenomenon.
- For all discussions in the results section, the graphs are provided after the description. As a reader, it is easier to follow through to the results if the graphs are provided first and then the discussion or atleast each page can have the graph and its discussion.
- Page 3, line 113-116 in the Results and Discussion section, please provide more than two references if the authors state that “The mechanism of hydrophilization transformation for the porous low-k material upon O2 plasma irradiation has been reported by many researchers [19,20].”
- Page 6, line 175-182 in the Results and Discussion section, the authors need to provide reference for the phenomenon as described.
- In the Results and Discussion section, for all the water contact angle (WCA) measurements, the authors provide approximate “~” values for all the measurements. Standard deviations (SD) need to be provided for the measurements as it will define if the WCA are consistent from sample to sample.
- Page 8, line 202 in the Results and Discussion section, the authors mention using ten samples for Figure 7. Is this true for all the results ? The authors must provide the SD for all measurements and plotted graphs. All the figures plotted does not indicate any SD which leads to believe that the experiment was performed only once. If the standard deviations are too small then authors can tabulate and provide in the paper.
Author Response
The paper is very well articulated, providing various characterizations and application of such fabrication method will indeed improves interconnects used in MEMS based devices. However, the authors need to address the following comments to improve the paper and provide more clarity. I would encourage the authors to resubmit and improve the paper based on the comments.
- Page 1, line 35-37 in the Introduction section, the authors need to provide reference for the phenomenon.
[Reply] We had added the related reference in the revised manuscript.
- In the introduction section please clarify why SiOCH film was chosen. What are the advantages over other available films in use?
[Reply] We had described the advantages of the used SiOCH film in the introduction section.
- Page 2, line 77 in the Experimental section, please rewrite the sentence and give a description in a couple lines about the process. Please refrain from using the term “elsewhere”.
[Reply] We had described the advantages of the used SiOCH film in the introduction section.
- Page 3, line 112 in the Results and Discussion section, the authors can rewrite the sentence as “It was observed that as the RF power was turned on for HDMS plasma treatment, the thickness increased with increasing plasma treatment time”.
[Reply] Thanks for reviewer’s suggestion! We had rewritten this sentence in the revised manuscript.
- Page 3, line 113-116 in the Results and Discussion section, the authors must provide a reference for the phenomenon.
[Reply] We had added the related reference in the revised manuscript.
- For all discussions in the results section, the graphs are provided after the description. As a reader, it is easier to follow through to the results if the graphs are provided first and then the discussion or atleast each page can have the graph and its discussion.
[Reply] The final version will follow this rule.
- Page 3, line 113-116 in the Results and Discussion section, please provide more than two references if the authors state that “The mechanism of hydrophilization transformation for the porous low-k material upon O2 plasma irradiation has been reported by many researchers [19,20].”
[Reply] We had added the related reference in the revised manuscript.
- Page 6, line 175-182 in the Results and Discussion section, the authors need to provide reference for the phenomenon as described.
[Reply] We had added the related reference in the revised manuscript.
- In the Results and Discussion section, for all the water contact angle (WCA) measurements, the authors provide approximate “~” values for all the measurements. Standard deviations (SD) need to be provided for the measurements as it will define if the WCA are consistent from sample to sample.
[Reply] We had removed the “~” from the manuscript and added “The reported WCA value was the average of five measurements. The measurement variation was within 1â—¦ for each condition” in the revised manuscript.
- Page 8, line 202 in the Results and Discussion section, the authors mention using ten samples for Figure 7. Is this true for all the results ? The authors must provide the SD for all measurements and plotted graphs. All the figures plotted does not indicate any SD which leads to believe that the experiment was performed only once. If the standard deviations are too small then authors can tabulate and provide in the paper.
[Reply] We had added error bars in Fig.7 in the revised manuscript.
Round 2
Reviewer 3 Report
All the comments has been satisfactorily addressed.
