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Photo Mask order Requirements
Resolutions:
Our Maskwriter is capable of imaging at 3 different resolutions: 16,000 dpi, 32,000 dpi and 64,000 dpi, referred to as LOW, MEDIUM and HIGH resolutions.
When writing glass masks directly on the maskwriter, we always image at HIGH resolution.
When imaging polyester films, we then have a choice of resolutions to use. Photographic film has a ‘grain’ size of approx. 25,000 dpi. However, even though the grain size is smaller than the resolution, we still recommend higher resolutions due to the ‘nucleation’ effect of the silver halide material.
We only recommend LOW resolution when the feature sizes are large (100 um +) and all of the features are lines at either 0 or 90 degrees. When features are smaller, then we would recommend MEDIUM resolution. If a design has very small features (<30 um) or the design contains arcs and circles or lines at angles other than 0/90 deg, then we would recommend HIGH resolution.
Film Photomasks
We can image onto mask films from 10” x 12” up to 36” x 24” (although we are able to manufacture films at 4000 dpi upto 3 metres long!) . The photographic film used is a polyester-based film with a dense photographic emulsion. Typical density is 4.5 log + transmittance. The films are packaged in individual polythene bags and shipped flat in boxes. Photographic emulsion is fairly soft, and must be handled carefully to avoid scratches and marking of the image.
The smallest feature that we can image on photographic films is 5um, depending upon the type of geometry used.
Although one benefit of photographic film is that it is cheaper than glass masks, some users may find problems with dimensional stability. The polyester base will grow/shrink depending upon the temperature and humidity that it is used in. This can make big changes in overall dimensions, especially on larger films. We image and store all films at
50 % humidity and 21 deg C, and recommend that you use the same parameters to ensure dimensional accuracy. We have a web page on-line where you can calculate differences.........back
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Glass Masks:
Our most common stock of plates is 3”, 4”, 5” and 6” glass mask blanks all of which are 0.060” thick. We also have some larger blanks that can be cut down to suit your size requirements. The largest mask that we can make is 36” x 24” – although we don’t carry these blanks in stock. Other sizes can be sourced depending upon your requirements, but may have longer lead times.
Standard soda lime glass, which we use for both Chrome and Emulsion masks, has a thermal coefficient expansion of (50-200Cx10-7) of 93..........back
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Chrome Plates
These are available on Soda Lime glass with transmittance value of 88% at 375-450nm, with a glass flatness class of 5um. The chrome has an optical density of 3.0 at 450nm and a reflectivity of 11% at 436nm. Unless otherwise requested, all orders for Chrome photomasks will be supplied with Low Reflective chrome. If the glass plate size you require is not shown above, then please contact us directly...........back
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Emulsion Plates
All Glass plates are orthochromatic glass plates, 0.060” thick, with ultra high resolution (up to 50,000 dpi). These plates are available in different overall dimensions, but always supplied in glass flatness class 5 µm/inch or 3 µm/inch. The emulsion is similar to the photographic emulsion on film, in that it needs to be handled carefully to avoid scuffs and scratches. If the glass plate size you require is not shown above, then please contact us directly...........back
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Quality
The smallest clearfield feature that we can image is between 5um and 6um for darkfield.- this includes spaces between features so our smallest line must be at least 5um away from the next object, otherwise we risk the chance of these objects merging together.
The masks are placed on the imager and aligned by hand. Please allow 1mm tolerance for the image to be centroid to the mask edge. Because of this, we also prefer a minimum spacing of 10mm of clear data around the edge of the mask. Chrome masks need a larger clearance in the corners where chrome and resist are thicker. We recommend at least 20mm clear of data near the corners of the mask.
Although we aim to keep our process as clean as possible throughout the production process, which includes the use of cleanroom packaging, please understand that we do not yet have a calibrated cleanroom and there is a slight risk of contaminates during production. Pinholes may occur, and if the risk of one pinhole means that the whole job is ruined then our process is probably not suited to your products.
Minimum feature: 5um depending on feature geometry and substrate used Feature and dimensional tolerances are available on request.
NOTE - we use a completely new type of mask process imager to manufacture masks. Although we aim to manufacture a good quality mask with accurate dimensions, we do not use E-Beam or Laser Imaging equipment and we do not intend to compete with the quality of these conventional masks. However, what we excel at is an UNBEATABLE turn-round and price, making our application ideal for prototypes, development and R&D type work...........back
Inspection
All masks are given a 100% inspection by eye. This includes an overall inspection for any defects, inspection for flaws and contaminates and an inspection for pinholes and breaks. The inspection process utilises microscopes and lupes and sample areas are checked for edge definition and line quality. Please see our quoted defect standards below.
Fully Certified Inspection – By selecting this option during the ordering process, we will inspect upto 10 user defined measurements. 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. Our standard tolerances for features and dimensions are used unless you instruct us otherwise. There can be upto 10 positions defined by the customer. These dimensions are then programmed onto the co-ordinate measuring system and the mask is compared to this unique program. A certificate of conformity is given if the mask passes the inspection process..........back
Defects
The process of our manufacturing, and the specification of the plates and photo-resist, means that there may be minor defects that appear randomly across the image. Usually these defects are cosmetic only, and sometimes the defect actually causes no working problem with the design. A defect is defined as having a size greater than the quoted rate below, and can either be a "pinhole" in what should be the chrome/emulsion part of the mask, or it can be a chrome / emulsion spot in the clear part of the mask (also referred to as 'shorts' or 'breaks').
Micro Banding is another effect, and refers to what can show up on masks that have large gratings, or masks that have many thousands of small repeatable patterns such as lines or dots. This microbanding is an optical phenomenon, which is easily visible with the naked eye, even though the mask features may be well within tolerances. The eye is an amazing inspection instrument, and can easily detect pattern variations often be less than 1 um. The banding effect may be of importance for certain display applications, but it often does not affect many other photomask uses.
Quoted Defects for standard materials/service: Less than 1defect per square inch Defects: greater than 5 microns in size...........back
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Data
Our preferred formats are Gerber, followed by DXF or DWG. There is no CAD charge for ‘clean’ data sent in Gerber formats. We can also take data as GDSii, HPGL, IGES, CIF, Mentor etc. These formats will incur a CAD charge...........back
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Polarity / Format
We refer to our masks as Clearfield / Darkfield. This is the best way to describe if a mask is Positive or Negative. For example, Clearfield means that the data you have drawn in CAD will be Black/Opaque on the mask, with the background being clear. Darkfield is obviously the opposite of this, where the items drawn on CAD will be clear and the background will be dark. YOU MUST SPECIFY THIS FORMAT ON YOUR ORDER..........back
Orientation
In order for the mask to work correctly in your contact exposure, we have to image it the right way round! We need to know which way round the mask has been designed, please specify one of the following when ordering Design is viewed from Chrome/Emulsion side Design is viewed from Glass/Polyester side.......... back
Schedule
Our standard turnround for PhotoMasks is 2-4 days from receipt of good clean working data. (Films masks are often turned round within 1-2 days and glass masks usually take 3-4 days but these may vary depending on current workloads).
A premium service, of either 48hrs or sameday, can be requested. A sameday service in the UK means that the mask will be shipped the same day as the order is received. We must have the order and data by 9.30am to enable us to honour this fast turnround.
Our 48hr service means that we will ship goods within 2 days of receiving the order. For this premium service, we will need orders to be with us by 10.30am. .
For overseas customers, please allow for time zone differences. As a general guide, we are 1hr behind Central Europe Time, 8hrs behind US West Coast time, and 4 hours in front of US East Coast time. For the premium services to work efficiently, the data and order must be with us by the time specified and most importantly the data must be designed in accordance with our design rule guides and be ‘ready-to-go’. Most delays in production occur where data is ambiguous or wrong...........back
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Orders
We can accept authorised purchase orders from Universities, Government Depts. and PLC’s (Public Limited Companies) without the need for credit accounts to be set-up. All others will need to have a credit account set up before we ship goods. This credit account will take 5 days to register from the date of the first order. All subsequent orders can then be taken on account. Alternatively, we accept most major credit/debit cards that will speed up the processing of the first order...........back
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Shipping
We ship by Royal Mail registered Post in the UK, and FedEx to the USA and European EC countries. All of these services give an on-line tracking method. You will be emailed your tracking number on dispatch of the mask.
We have a full on-line tracking system for your orders on our website. You will need to request a user name and password before access to this site...........back
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Invoicing
We invoice at the same time as shipping, by default in UK £ sterling although we can also invoice in $ US and € Eu. We can also accept payments in £ sterling, US$ or Euro's. These payments can be made by cheque or by direct payment into the relevant currency account. If you intend to pay by either US$ or Euro’s, please contact jo.daniel@jdphoto.co.uk for the agreed amount after currency conversion. We expect payment of invoices within 30 days of the end of the invoice month...........back
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