We now succeeded in finding a remarkable solution for high-layer e-beam structuring. The negative resist CAR 44 (AR-N 4400-10) was coated to yield a layer with a height of 9.5 μm, dried, and irradiated.
A new application field for Atlas 46 is electron beam lithography, as experiments with a thin Atlas resist layer patterned by e-beam lithography demonstrated. At a layer thickness of 450 nm, 200 nm lines were written into this layer. The sensitivity was 70 μC/cm² at an acceleration voltage of 100 kV.
In the final stage of the Eurostar PPA-Litho project which was aimed to develop the resist Phoenix, we achieved to generate far more stable PPA polymers by optimizing the synthesis procedure. Pure polyphthalaldehydes which were subjected to a “stress test” for 14 days at 37 °C showed no decomposition. These resists can thus be shipped without cooling; this however only applies to pure PPA polymers.
Fluorescence is the spontaneous emission of light briefly after a substance is excited by electronic transitions. The emitted light has usually less energy than the previously absorbed light.
Semi-precious stones like sapphire or garnet increasingly gain in importance as substrates for semiconductor industry. Even though these materials have insulating properties, a patterning with electron beam lithography is nevertheless possible with the help of Electra.
Novolac-based e-beam resists have other surface properties than e.g. CSAR 62, PMMA, or HSQ resists. Due to a higher solvent content of the conductive resist as for example is the case with SX AR-PC 5000/90.2, these novolac-resists are already moderately attacked.
The measured conductivity of resist layers is strongly influenced not only by the temperature but also directly dependent on the air humidity. After a softbake, the now almost anhydrous layer gradually takes up water at room temperature from the ambient air due to the slightly hygroscopic properties of the polymer.
To assess the long-term stability of Electra 92 (SX AR-PC 5000/90.2), two reference samples were coated on glass (300 rpm, 3 min, softbake at 85 °C for 30 min in the oven) after different storage times of 15 months and 3 months, respectively (refrigerator, 8 °C).
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A direct positive patterning of PPA layers is possible by electron bombardment. Similar to the irradiation of normally used e-beam resists like e.g. CSAR 62 or PMMA, the electron beam causes a fragmentation of the polymer chains.
Within the scope of the Eurostar project PPA-Litho, Allresist currently evaluates innovative high-quality resists on poly(phthalaldehyde) (PPA) basis in cooperation with the company Aglycon, the Joanneum Research in Weiz, and the SwissLitho AG in Zurich.