Making a photomask

Creating a photomask

This is a simple guide on the steps required to make a photomask.

If you are intending to use the mask aligner in SIOS then the mask size that you require is 4x4inch and your design must take into account the aperture of the aligner which is approximately 3.5 Inches in diameter.

The design of the mask can be layed out using any cad type package but we usually use dwf/dwg formats, and this can be made with qcad in linux or autocad in windows. Autocad 2005 is available through Microsoft Application Virtualization (access may require an email to IS asking to be added to the permitted user list). There are some important rules to obey when doing your design.

• Do not go too close to the edge of the mask, eg. Leave a 5-10mm gap from the edge.
• Try to align features on a grid, this makes it easier for the machine that writes the mask.
• The most detailed features (requiring the highest resolution) should go into the centre of the mask.
• Work radially outwards with increasing feature size from the centre

The company we use for producing photomasks is www.jdphoto.co.uk. They have a good website covering what services they offer and a price calculator. A local copy of the most recent design guide for photomasks is available here. (link to local copy pdf date it)

If you are making features with interior holes these have to be carefully drawn as the plotter may not draw what you expect. There are a number of ways to make sure your final image comes out how you expect it to. The easiest way is to draw all the holes on one layer and all the main parts on another. When submitting the drawing file add a note saying that the final image will be main layer - hole layer. when they build your proff they will take this into account add all should be as you expect

Otherwise you can achieve the same thing using solids and solid subtraction, or using polylines drawn very carefully making sure not to intersect other lines. There is a section on this in the drawing rules guide which goes into more detail.

How to order

Fill in the online form to order a mask, with all the setting you require,make sure you tick the box asking for a proof, do not submit it, print it out. Fill in an EEE order from using the price from the online calculator for the options chosen in the printed form. take these to Jo Mee who will complete the order online.

When you receive an order confirmation email from EEE or JDphotomask, you can then email them your drawing file specify how the final image should be made. for example, what should be transparent, which layers to use etc.

Once they have checked your file you will receive a pdf proof of your design, this has to be checked and an email confirmation to go ahead with the design needs to be sent. They will then make your design and send it to you.

Checking requirements

They can be contacted by

• Phone 0161 627 2949
• Email sales@jdphoto.co.uk
• online live web chat http://www.jdphoto.co.uk/ on contact page,

they are generally very helpful.