To build a complete photolithography system, you need the following four components in addition to our Flood Exposure Sources:
• Mask Alignment Fixture
• Substrate or Wafer Holder
• Photomask Holder
• Precision Slide
In very simple terms, the assembly resembles a movable waffle iron with micrometer adjustments. The base is the Mask Alignment Fixture, which provides X-Y-Z positioning of the "waffle." The waffle, or substrate, rests on top of the fixture in a Substrate Holder; and lastly, the lid is a Mask Holder with mask in place, which closes down over the substrate. With the substrate loaded and aligned to the mask, the assembly is manually moved into position for exposure under the collimating lens of the Illumination Source using a Slide. Exposure occurs by opening and closing the light source shutter. After exposure, the assembly is returned to its starting location for removal of the substrate.
Fig. 1 Four components of a basis Photolithography System.
Mask Alignment Fixture
The 83210-V is a fixture, which holds one mounted substrate (or wafer) and mounted mask holder for each size of substrate (substrate and mask holders must be purchased separately). It accommodates substrates from 1 x 1 inch (25.4x25.4 mm) up to 6 x 6 inches (152.4x152.4 mm) and corresponding masks from 2 x 2 inches (50.8x50.8 mm) up to 7 x 7 inches (177.8x177.8 mm). Change substrate sizes with a simple interchange of substrate and mask holders. Use the vacuum contact mode for moderate resolution of image features 2 microns in dimension. If mask wear is a concern, operate in the proximity printing mode with a resolution of 25 microns.
Substrate or Wafer Holder
Our substrate and wafer holders have vacuum hold down that holds them in place during alignment and exposure. Substrate holders use three hardened steel pins for coarse alignment. The wafer holders have two flats, which mate to the flats on the wafer for coarse alignment. These holders hold substrates or wafers from 1 x 1 inch (25.4x25.4 mm) up to 6 x 6 inches (152.4x152.4 mm) with a maximum thickness of 0.25-inches (6.35 mm). Custom sizes, e.g. a wafer holder to position both a 4-inch (101.6 mm) OD and 5-inch (127 mm) OD wafer to a 6-inch (152.4 mm) mask, are available upon request. Contact a Sales Engineer with your requirements.
Photomask Holder
Photomask holders have a frame that mates to the top and sides of the mask while the bottom of the mask rests on a closed cell neoprene gasket. During vacuum contact, the mask and substrate are pulled together. Masks up to 0.25-inches (6.35 mm) thick are held mechanically against three hardened steel pins. Our design requires that the mask be 1-inch (25.4 mm) larger in perimeter than the substrate, e.g. a 6 x 6 inch (152.4x152.4 mm) substrate or 6 inch (152.4 mm) OD wafer mates to a 7 x 7 inch (177.8 x177.8 mm) photomask.
Precision Slide Assemblies
Our Flood Exposure Housings remain stationary while the 83210-V Mask Alignment Fixture moves under the collimating lens for illumination. Two different slide assemblies are offered:
- 83211 with 12-inch (304.8 mm) travel
- 83212 with 24-inch (609.6 mm) travel
Simple, Precise Alignment
With Newport’s alignment fixtures you can quickly and easily align your substrates and wafers without compromising accuracy. Our unique design incorporates three micrometers, which are aligned with fiducial marks on the mask and substrate to allow simple, rapid and repeatable alignment. Our innovative 3-Step Alignment design eliminates unnecessary micrometer adjustment , as two of the three micrometers create a pivot for each other.
The vertical (Z) motion provides high resolution positioning of the substrate relative to the mask. The full range of motion covers 0.245-inches (6.223 mm) and proximity spacing can be set for substrates up to 0.24-inches (6.096 mm).
The substrate stage of the 83210-V Alignment Fixture rests upon 3 threaded vertical adjustments that are connected together. Two of the three controls are independently adjustable to obtain optimal planarization of the substrate. This is useful when working with wedge shaped or loose tolerance substrates.
Optional Components to Build Fully Featured Systems
Viewing Systems
- Stereo Zoom Microscope
- Split Field Microscope
Stereo Zoom Microscope
The Stereo Zoom, a modestly priced product, comes with an X-Y-Z positioning mount and an illumination source for the substrate and mask. It permits rapid scanning, aligning one registration mark at a time with magnification to 90X.
Split Field Microscope
The Split Field Microscope permits simultaneous viewing of two separated registration marks, greatly improving operator alignment productivity. Varying microscope objectives are offered with the 20X producing an image of 460X. Purchase an 85135 X-Y Stage separately for translation across the substrate. A unique approach to substrate illumination permits optimum image contrast. The 85120 Bright-Field Illumination Source is used for highly reflective materials such as silicon wafers and the 85121 Dark-Field Illumination Source is used for low reflective materials such as ceramic.
The 85129 Video Monitoring Kit is an option to view the substrate and mask split field images on a monitor.
Optical Tables
Our vibration isolated Optical Tables ensure a stable environment for the substrate and components. We offer various sizes and vibration capabilities.
Fig. 2 The above is a guideline to use in selection of components when building a photolithography system. However, before placing your order, we highly recommend that you contact an Applications Engineer to determine the correct products for your specific application.
