Articles you may be interested inSynthesis and characterization of an organogermanium resist: Poly(trimethylgermylmethyl methacrylate-co-chloromethylstyrene) J. Vac. Sci. Technol. B 7, 1723 (1989 10.1116/1.584446 Nanometer lithography for III-V semiconductor wires using chloromethylated poly-α-methylstyrene resist Molecular parameters and lithographic performance of poly(glycidyl methacrylate-co-ethyl acrylate): A negative electron resistThe lithographic performance of the resist system poly(p-methylstyrene-co-chloromethylstyrene) PMS-CMS has been assessed. Copolymerization of the monomers, PMS and CMS, produced resists with CMS increasing from 0% to 52%, molecular weights between 122000 and 167000, and dispersivities between 1.7 and 2.3. The sensitivity (D~·S) and contrast of pure PMS for 20 kV electrons was 38 pC cm-2 and 2.8, respectively. Addition of 4.2% CMS increased the sensitivity to 2.1 pC cm -2 but only reduced the contrast to 2.3, a value sufficient for submicron resolution. Further increases in CMS content, to 52%, produced smooth variations in sensitivity and contrastto 1.2 pC cm -2 and 1.5, respectively. Exposure of 4.5% CMS resist with deep UV light (22 mJ cm-2 ) produced 1 pm lines and spaces with vertical profiles. The etch rate of this resist, during poly-Si definition in a chlorine plasma, was almost half that ~f the photoresist HPR206.r

Synthesis and lithographic characterization of a series of negative acting electron sensitive resists based on poly(4-methylstyrenexo-chloromethylstyrene) are reported. The sensitivity and contrast of these resists were found to depend on the chloroniethylstyrcnc (CMS) content and an optimum value of 5wt% was determined from consideration of parameters associated with the reproducibility of the synthetic method and also the lithographic performance. Both the sensitivity and resolution were found to depend on the molecular weight and CMS content of the copolymer. Several methods of scale up for the synthesis were explored, the route having a very significant influence on the film formation characteristics of the resists. The reactivity ratios of the monomers were measured in order that the compositional drift, which occurs during the synthesis, could be quantified. The effect of solvent composition and molecular weight of the copolymer were explored in relation to the quality of the resulting lithography. These studies have indicated that the copolymer has the potential of being used as a VLSI sub-micron resist with good plasma etch resistance.

Capacitor coupled logic circuits using depletion-mode Schottky-gate GaAs transistors are being made by direct electron beam exposure with a Cambridge Instruments EBMF-1. Etched active mesas are defined using either a negative working polystyrene based resist or positive working PMMA. The use of PMMA is possible following the development of a tone reversal program for the PDP 11/34 EBMF-1 control computer. The chips have 2 mm sides and each is written in a single field. Automatic registration of the FET electrodes is accomplished using topographic marks for the source/drain level and metal marks for the gate and subsequent layers. The source/drain and gate metallizations are defined by liftoff using PMMA. Software to correct the intraproximity effect within individual exposure features has been developed, and applied to the 1.5 μm gate structures. The dose given to a feature and its dimensions are simultaneously adjusted to obtain the correct feature size and resist profile for liftoff metallization. In subsequent steps a polyimide insulation layer and a metal interconnect level are defined to complete the circuit.

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