Lateral Fractal Formation by Crystallographic Silicon Micromachining
Round 1
Reviewer 1 Report
Properties of the system of crystallographic planes of silicon are used to fabricate a series of pyramidal features by using the corner lithography technique.
Individual steps of etching procedures are theoretically modeled and in the technological operations, suitable etchants and conditions are thoroughly selected.
By applying this approach authors formed several generations of pyramidal shapes, studied individual properties of pyramidal shapes in subsequent generations,
documented problems connected with the etching of subsequent features and estimated and applied suitable technological restrictions.
The theoretical background of the used method is nicely described in the supplement material. In a conclusion, the chapter authors discuss a possible number of fractal pyramidal generations and the size limitations of formed features.
Manuscript, chapter selections, figures illustrating the method principle, theoretical background, and discussion of selected problems are processed at a high professional level.
Author Response
Thank you for reviewing the paper and your kind words about it.
Reviewer 2 Report
Сomments and suggestions are set out in the attached PDF file
Comments for author File: 
Comments.pdf
Author Response
Thank you for the kind words and the reviewing of and commenting on the paper. You mention 3 points of attention that we took into consideration. Please find here our comments and applied adaptions as a response to it.
1: In the work we describe the formation of 4 generations, however the initial generation we call G0 since the processing needed for the initial generation is different that for all following fractals while in essence the resulting shape is the same. That means that generation G1 up and to G3 use the same processing, but in total we have generation G0 up and to G3. To prevent further confusion we renamed them in the paper to G1 up and to G4.
2: We have added the analytical expressions/formulae used for the plot in the appendix and referred to them from the text for those who are interested. As for the etching rate, we use a standard conformal slow etching process, meaning all material/Si3N4 in all corners has the same etching rate while there is no transport limitation taking place or suchlike. The absolute difference between the reduction of the width of the corners is solely due to the geometry. It is all determined from the angle of the corner and also somewhat due the total etch-length (geometric factor, GF in the text), but this is again defined by the angle of the corner. Simplistically said, a wider angle will result in a bigger absolute reduction of the etched dot per etchfactor (EF) while etching.
3: Assuming you mean the information about the type of SEM, used parameters and further preparation of samples, we now added the information of the used SEM and the parameters in a table in the SI. The sample preparation is now also mentioned in the main text.
As for the suggestion for splitting the used materials/equipment and experimental work. We considered this, but since we use several machines multiple times with different settings, we believe the text stays more readable as it is now, than to split it up in different sections. For being able to reproduce and fully understand it then, one would need to go back and forth per process step to find out which settings are used. If we would leave only the particular settings in the current text, it would also leave most of the text as it is now with the addition of needing to go back and forth to see which machine was used with the settings.
