Photolithography, a patterning process

With the help of lithography machines light sensitive polymers or photoresists are exposed by UV light source and developed with chemical means to form 3D relief images or objects on carrying substrate.

Our lithography process

The lithography process involving DaLI is achieved by selective exposure of photoresist using guided laser beam. No photomask lithography is required. Photolithography process is widely used in semiconductor and printed circuit board production industry, but it can be applied in other fields, such as MEMS, lab on a chip, microfluidics, photomask production, quantum devices, micro optics. In these fields the design of a new device is often iterative, that is why the maskless photolithography process proves useful, offering rapid product development in-house at no cost and waiting for new and expensive versions of photolithography masks.

Masklesslithographybasic
Ultimate_precision

Illumination resolution far below 1um

Not_limited

Not limited by physical properties of the substrate or its surface

Photomask

Change pattern design from one run to the next, without incurring the cost of a new photomask

Aspect_ratio_40-1

Aspect ratio (height/width of channel) up to 40 achieved

Level

Grayscale illumination

Ultimate_precision

Illumination resolution far below 1um

Not_limited

Not limited by physical properties of the substrate or its surface

Photomask

Change pattern design from one run to the next, without incurring the cost of a new photomask

Aspect_ratio_40-1

Aspect ratio (height/width of channel) up to 40 achieved

Level

Grayscale illumination

SW-joprocess

Easy transfer of design to substrate

Full PC control and an intuitive lithography software drastically shorten prototyping time and lower the costs, while maximizing flexibility that is required for in-house prototyping, research and development environments. The included CAD library allows designing from scratch or modifications of partially or fully ready patterns even on a standalone PC without the DaLI system connected. Import filters can import design in dxf and bmp formats. One can assign different illumination parameters to individual parts of structures, e.g. the diameter of laser beam, the illumination dose, the illumination resolution, mode, and place of stitching the fields and many more. But one can always simply trust to the default values. By employing an integrated microscope, it is possible to level the substrate to bring its surface into laser focus, determine the location of eventual related patterns or objects, perform various geometric measurements, etc. However, once the values of key illumination parameters are determined, just trigger the illumination with one click and watch the illumination process in the job processor window.

miDALIX
Ultimate_precision

Nanometer precision inside a single illumination field

AOD

More than 100000 random dots per second illuminated employing AOD

Aspect_ratio

Substrate size from few micrometers to full 100×100 mm (4 inch)

Ultimate_precision

Nanometer precision inside a single illumination field

AOD

More than 100000 random dots per second illuminated employing AOD

Aspect_ratio

Substrate size from few micrometers to full 100×100 mm (4 inch)

Location

5 axis positioning of substrate – automatic leveling supported

Software_operated

Entirely software operated

Level

Few hundred intensity levels

Location

5 axis positioning of substrate – automatic leveling supported

Software_operated

Entirely software operated

Level

Few hundred intensity levels

Thermometer

Temperature controlled by solid state chiller

File

CAD with DXF and BMP import filters implemented

Patter

Design patterns on a standalone PC

Thermometer

Temperature controlled by solid state chiller

File

CAD with DXF and BMP import filters implemented

Patter

Design patterns on a standalone PC

Become more efficient with DaLI

Let your idea become a design, your design be illuminated as a structure, and your structure integrated in the experiment — all within a single day using a tabletop lithography system.

Become more efficient with DaLI

Let your idea become a design, your design be illuminated as a structure, and your structure integrated in the experiment — all within a single day using a tabletop lithography system.

Get to know lithography process steps

Substrate preparation proposes to improve the adhesion of the photoresist onto the substrate, and to prepare a contaminant-free resist film. This can be accomplished by cleaning a substrate to remove contamination, either organic or inorganic, with chemical cleaning, ozone, or plasma stripping. Adsorbed water is removed with dehydration bake — baking at temperatures of 200°C to 400°C for up to 60 minutes. The substrate needs to cool down and be coated immediately as water will reabsorb on the substrate surface, if left in a humid environment. Some substrates have poor adhesion and adhesion promoters should be used.

Coating of photoresist is accomplished by spin coating. A specific uniform film of photoresist is influenced by many controlling parameters, such as spinning speed and duration, spinning acceleration, physical properties of the photoresist and the substrate, method of dispensing and many others. To achieve a stable film, the solvent in photoresist is evaporated by heating up to prescribed temperature and time using an oven or a hot plate. During this step, called soft baking, photoresist’s adhesion to substrate is improved and film thickness slightly reduced. Other properties that influence following photolithography steps are significantly changed as well.

Illumination of a pattern using DaLI is achieved by employing precisely guided UV laser beam. Illumination of the photoresist dot by dot that corresponds exactly to predesigned pattern transfers CAD design to the photoresist without utilizing an intermediate photomask but with precisely controlling energy on each single dot of the pattern and pattern resolution. DaLI is automatically switching among user assigned optical paths that shape UV laser light into beams with nominal diameters 1 µm or 3 µm. Combination of both laser beam diameters (tools) within a single pattern assures high resolution illumination with short illumination times.

The illumination of a photoresist influences its solubility when wetted by the developer. Development process dissolves either exposed (positive tone) or unexposed (negative tone) photoresist areas. In case of negative tone photoresist, a post exposure bake is mandatory prior to development. Development can be done by dipping a sample in developer, spraying, or spinning it over photoresist. Development process latitude and its uniformity is influenced by development methods as well. Each development process is unique, and parameters must be adapted based on photoresist, type of developer, its concentration and many other input variables.

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        Technical information

        General

        Substrate size, mm

        from sub-millimeter to 100 x 100 x 10

        Supported photoresists

        all common photoresists

        Optical Characteristics

        Laser wavelength, nm

        375 or 405

        Laser beam spot size, µm

        1 and 3 (software-selectable)

        Performance

        Writing resolution (beam positioning)

        true sub-nanometer

        Writing speed (spots per second), Hz

        100,000

        Minimum structure size, µm

        <1

        Structure aspect ratio

        more than 1:20

        Multilayer alignment accuracy, µm

        0.5

        User Interface

        Data input formats

        DXF, BMP

        Intuitive CAD software for design, alignment, advanced anchoring and exposure control

        Integrated optical monochrome or color microscope for inspection and alignment

        Technical Data

        Operating temperature, °C

        21.5 ± 1.5

        Operating relative humidity, %

        <80, non-condensing

        System dimensions (W x D x H), mm

        650 x 626 x 522

        System weight, kg

        77

        Electrical supply voltage

        110-230 VAC, 50/60 Hz

        Power consumption, VA

        <120

        Hardware/software requirements

        Windows 10 / 8.1 / 8, 64 bit, 3 GHz processor with SSE2 or higher, 4 GB of RAM and 16 GB available hard disk space

        Chiller data

        133 x 483 x 559 mm³ (19” rack, 3U), 15 kg, 250 W cooling / heating capacity

        All inclusive

        The DaLI system is shipped with the chiller, all connecting cables, coolant hoses and the proprietary DaLI software.