4 inch Chrome Photomask

CHOOSING RESOLUTIONS

We can write masks at 4 different resolutions, called "classes". The higher the Class, the better the quality. For each increase in Class, there will be a 2x improvement in the following parameters: Addressability, Minimum Line, Edge Roughness, CD Uniformity, and Alignment Accuracy.  Please also see the TAB section SPECIFICATIONS to see the impact that class resolution has on dimensional accuracy and feature tolerances. 

Some features are harder than others to replicate on the photomask. For example, a triangle with a 15um base / height will in fact have an apex point that reduces down to zero - these end apex points will be impossible to reproduce accurately regardless of the class chosen - but picking a higher class will reduce the rounding effect at each apex.  So, even though Class 1 is capable of reproducing 15um lines, a 15um triangle will be distorted in appearance due to this rounding on the apex points.   The same can be said for squares or other polygons with squared corners. If your design uses these type of features (triangles, squares, acute or obtuse corner angles) then pick the highest resolution for your budget. 

Sharpness of line edges - especially with rounded draws and arcs - are controlled by the Addressability and Edge Roughness. Again, consider using a higher class resolution if these are important to your design. 

Class 1 :   This represents a resolution that is drawn with a 8um pixel.  Although this resolution may resolve smaller features, we recommend keeping feature sizes above 15um as corner rounding is considerable. Edge sharpness and definition is acceptable for non-critical design types, although designs with arcs/circles and lines running off 90 degree grid may show pixilation. NO features such as lines / circles / spots / squares below 10 um unless on a `best effort` basis agreed with our technicians.    

Class 2 :   This represents a resolution that is drawn with a 4um pixel  Although this resolution may resolve 4um lines, we recommend keeping feature sizes above 6um. This resolution has good line edge qualities with only a small pixilation along edges. NO features such as circles / spots / squares below 6um unless on a `best effort` basis previously with our technicians.  

Class 3 :   This represents our most common resolution for demanding, high precision photomasks. This represents a resolution that is drawn with a 1um pixel, and offers an excellent price / quality balance. This resolution will resolve down to 2 micron lines, and has very good line edge qualities with no pixilation along edges, and corner rounding is minimal on larger features. 

Class 4 :   This represents our highest resolution, and is drawn with a 0.5um pixel, and is the best quality that we can offer. This resolution will resolve down to 1 micron lines and has excellent line edge qualities with no pixilation along edges.

MIN CD

CD means "Critical Dimension" and is often used to describe the smallest feature on the design. Feature in this instance can mean drawn data, and also spaces between drawn data. Putting a correct value here helps us determine inspection and production processes. Please use the NOTES section if you need to convey to us any other information.

CAD FORMAT

Data formats listed above are only a small section of what is available. Please note that printing based formats such as Corel Draw, PDF, Postscript, SVG, BMP, TIFF etc are not created to allow sub micron positioning, and we often see these formats export data that can be inaccurate at the micron level. For all Class 3 and Class 4 type work, we strongly recomend using Engineering vector type formats such as Gerber, GDSii, DXF, CIF etc. If your chosen format is not listed, please contact us for further information and clarification. We are also able to provide a full drafting service whereby we can create your designs from drawings and descriptions.

PRODUCTION SCHEDULE

Our standard production turnaround is 3-4 days from receipt of the artwork, purchase order and related documents. We generally send checkplots with every order, and it is vital that these are replied to within a short delay in order that we can meet the schedule required. The production schedule assumes the original data package is correct and does not need to undergo revisions or changes. For large volume orders, or large photomasks on high resolutions, please enquire before ordering premium services.

Standard (3-4 days) :   This is our standard service, and whilst we get 99% of orders shipped within this period, these are guidelines only and may change in periods of high demand. Where data packages are good, and all paperwork is completed promptly, we can often ship early.  Expected return of checkplot by customer is within 4 hours. Any orders received after 1pm will assume day 1 to be the following day.   

2 Days :   A premium service. A complete manufacturing package (data/instructions/order) must be with us by no later than 11.00am. Expected return of checkplot by customer is within 1 hour.

Sameday:   A premium service. A complete manufacturing package (data/instructions/order) must be with us by no later than 9.30am. Does not include Class 4 products, or photomasks bigger than 7". Expected return of checkplot by customer is within 30 mins.

5 Days + :   This is a discounted service for orders that are not urgent. Note that typical schedule is 5-10 days .

INSPECTION

Standard :   We firstly inspect the piece by eye for flaws, design inaccuracies and contaminations. We also inspect a test coupon (placed in the bottom corner of the mask) for line width accuracy and edge definition. Next we measure the overall dimension of the mask, and record both of these measurements on our internal inspection records. Finally, we find the CD of the mask, measure that, record it, and also take a digital photo that is saved with the inspection log. We use Nikon MM40 at 900x magnification and an OGP ZIP 300 at 400 x magnifications for this.

Enhanced :   In addition to the standard inspection process described above, we will then document them via a Certificate of Conformance which we supply with the mask. Tolerances are per our standard tolerances.

Full Certificate :   By selecting this option during the ordering process, we will inspect upto 10 customer defined measurements, with customer supplied tolerances. You will need to send us a document, or a separate layer of the design, showing us where you want us to take the measurements from. There can be upto 10 positions defined by the customer. These dimensions are then programmed on the co-ordinate measuring system and the mask is compared to this unique program. A certificate of measurement /conformity is given if the mask passes the inspection process.

CHECKPLOT

A method of sending an email copy of the design for verification before the mask is written. The ‘PDF Checkplot” is a low resolution (4000 dpi) graphic representation of the final photomask - the quality of the PDF does not represent the quality of the final photomask, it is a "gross overview". You must approve this by email before we can proceed.  

For more accurate checkplot representation , it is best to send you a detailed  CAD checkplot which will represent the design perfectly – in high resolution – and gives you the ability to also measure. You do not need to install any special software, we will give you the link to our online CAD viewer at the time of the checkplot.

YOUR DRAWING NUMBER

Please let us know the CAD file name / number so that we can tie together the uploaded data and the order.

NOTES

Here you can inform us of any other requirements or specifications regarding the order.