Negative-lithographic resists

Table VIII. Lithographic Properties of Selected Negative Electron Resists...

L.F. Thompson, J.P. Balantyne, andE.D. Feit, Molecular parameters and lithographic performance of poly(glycidyl methacrylate co ethyl acrylate) A negative electron resist, J. Vac. Sci. Technol. 12, 1280 (1975). 

Figure 12.4 Contrast curves for (a) positive-tone and (b) negative-tone resists. The intercept of the curve and abscissa in positive-tone resists is called the dose to clear" and is designated as Do, while in negative resists, it marks the onset of cross-linking, and is designated as Dq. This should not be confused with the lithographic dose to print, which tends to be approximately 1.6-2.2 times higher. The absolute value of the slope of the tangent to the contrast curve at its intercept with the abscissa is defined as the resist contrast. It is usually defined in terms of an auxiliary dose value Di, which is obtained by continuing the above tangent line to the full resist film thickness (normalized to 1.0).

Fig. 3. Lithographic process using positive- and negative-resist systems. The element (a) is (b), exposed to uv radiation (c), developed and (d), the metal is...

Figure 2 Typical lithographic response (contrast) curves for (a) positive and (b) negative resists.

Polymer molecular properties such as molecular weight and polydispersivity have a significant effect on the lithographic behavior of the single component negative resists described above. For example, it has been shown for a series of... 

The photoresponsive properties of molecular glasses also have been applied in the design of resists for semiconductor lithography. In a resist, irradiation changes the solubility of the materials, making it more or less soluble (positive or negative resist, respectively). The search for new resist materials follows the development of lithographic techniques toward deep-UV and electron beam... 

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