Dielectric Picture Fabrication
How to Make Your Own
Dielectric pictures are easy, just follow the step by step instructions.
- Reference Material
- References on the fabrication of color pictures
- Aaron Hawkins, R. Wang, G. Sanber, J. Beutler, and S. Schultz, "Color Pictures Using Dielectric Films," Color Res. and Appl., (accepted).
- J. Kvavle, C. Bell, J. Henrie, S. Schultz, and A. Hawkins, "Improvement to reflective dielectric film color pictures," Opt. Expr., vol. 12, p. 5789-5794, Nov. 2004.
Link to article
- Reference on the determination of colors
- J. Henrie, S. Kellis, S. Schultz, and A. Hawkins, "Electronic color charts for dielectric films on silicon," Opt. Exp., vol. 12, pp. 1464-1469, Apr. 2004.
Link to article
- General Information
- Color displays are typically made using ink or paint dyes. These dyes appear as certain colors because
each color of dye absorbs different portions of the incident light. Because dyes absorb light, they decay
over time, and consequently, pictures made using them eventually fade. Pictures made from thin dielectric
films on a reflective surface will never fade, even when constantly exposed to light. With dielectric
pictures, the colors in an image are created through optical interference rather than absorbtion. The following
tutorial steps through the process of making a RGB pixelated color picture in silicon dioxide grown on a
silicon wafer. Going through the process of making a dielectric picture is an excellent way to teach
the basics of photolithography and illustrates the color properties of different film thicknesses of
- The source image for our train picture.
- A pdf file of our first mask for green.
- A pdf file of our second mask for blue.
- A pdf file of our third mask for red.
- Choosing a Picture
- When choosing a picture, first consider picture size. Choose a picture that is X pixels long by X pixels
wide. This will be compatible with the software and fit on the wafer. Second, consider your color
scheme. Since it is very difficult to obtain a true red color with silicon dioxide, we recommend that
you choose a picture that has a minimal amount of red in it. This will render a more accurate
reproduction. Since green and blue dielectric layers are
quite brilliant and vivid in silicon dioxide, choose a picture that maximizes a color scheme of blue and
- Pixelating a Picture
- Don't forget Alignment Marks
- Once the picture is pixelated and in Skill, add alignment marks and whatever else you desire.
The layout consists of three dark field layers that will need to be converted to clear field layers.
(more on dark and clear field farther down) Be sure to design your alignment marks appropiately.
- Converting a Skill file to eps or Post Script
- Using Cadence, or another CAD program that uses Skill, export your document to a GDSII format. GDSII
is a good file format to use since it is accepted by many layout programs. Next, open the GDSII file
in a program that can convert it and save each layer of the file in a .eps or post script file. Here
at BYU, we use CleWin to convert a GDSII file into a post script file, but other programs exist that
can do the same thing.
- Making a Transparency
- We recommend that making your transparency on a high resolution printer that prints at 3600 dpi. Any
commercial grade printing company should be able to do this. Have the transparencies made clear field
rather than dark field, i.e. the transparencies will have dark features and a transparent
background. A dark field has transparent features and a dark background.
- Making a Photomask
- We strongly recommend that you use your transparency for the sole purpose of a template that
enables you to convert to a photomask. Using a photomask over a transparency is advantageous
because it allows easy alignment and multiple uses.
- Remember the following guidelines:
- 1. Handle all transparencies with gloves so oils from hands do not contaminate them.
- 2. Make sure that the transparency is placed flipped left to right on the resist side of
the mask. This will ensure that the picture and writing on the mask are in the correct
- 3. Be sure to secure the transparency flush with the plate. We recommend placing a completely
clear piece of photomask glass over the transparency.
- 4. Exposure can easily be done under an aligner.
- Wafer Preparation
- In a thermal oxidation furnace, grow 5200 angstroms of silicon dioxide on the wafers. This will give you a
green color--the first of your basis. Using basic photolithography, use the green mask and positive photoresist
to etch the down to a suitable blue color. Use the blue mask and positive photoresist to etch down to a suitable
red color. Then, use the red mask and negative photoresist to etch down to a red (more pink). After exposing and developing,
set the wafer with the negative photoresist on a hot plate at 400°C for at least 10 minutes. This will blacken the resist and help to give a
black background to the picture so that the colors are more vivid.