Positive resist performance

DNQ-novolac positive resists have been used also with e-beam exposure. The 2,1,4 DNQ isomers give superior performance in these applications (101). The e-beam sensitivity of these materials is 40 xC/cm2. 

The SAMPLE program (O is used to simulate exposure and development of features in the MP2400-17 positive resist. The three resist parameters A, B and C defined by Dill and coworkers ( ) and the solubility rates of the resist films as a function of exposure dose (or PAC content) must be determined to perform the simulation. 

Kurihara, M. Segawa, T. Okuno, D. Hayashi, N. Sano, H. Performance of a chemically amplified positive resist for next-generation photomask fabrication. Proc. SPIE 1998, 3412, 279-291. 

However, no aqueous resist system has been reported that has both high resolution and dry etch resistance. In order to design an aqueous processable positive resists with more practical performance, pure water was replaced with... 

Though conventional positive resists have performed well at 436,405, and 365 nm wavelength (common outputs of commercial exposure sources), the potential resolution gain has been small. This has given a push toward shorter wavelengths for achieving higher resolution. 

Photoacid diffusion behavior in t-BOC-blocked chemically amplified positive DUV resists under various conditions was studied. Based on the experimental results, it was confirmed that only one mechanism dominated the acid diffusion in the resist film, and two diffusion paths, i.e., the remaining solvent in the resist film and hydrophilic OH sites of base phenolic resin, existed. Moreover, the effects of molecular weight dispersion, acid structure, and additional base component on both acid-diffusion behavior and lithographic performance were revealed. Finally, the acid diffusion behavior in the resist film was clarified and the acid diffusion length that affected the resist performance could be controlled. 

A chemically amplified, positive-working resist system based on silylated polyhydroxystyrene has shown its capability for application to quarter micron lithography. The present paper describes the recent improvement in the resist performance achieved through studies on polymer characteristics and process conditions. Possible measures to suppress a peculiar problem of positive-working chemical amplification systems, i.e., formation of T-shaped profile, is also presented. Although the development is still on the way, the silylated polyhydroxystyrene based resist tem shows excellent properties on resolution capability, sensitivity and process latitude. 

A new family of chemically amplified positive resists based on methaaylate terpolymers has been developed. The three different monomers each perform a separate function in the terpolymer. These resists were original designed for use in printed circuit board (PCB) fabrication. The flexibility of this approach in the design of positive resists has recently been demonstrated in the development of several new integrated circuit (IC) positive resists for deep UV (248 nm) and deep, deep UV (193 nm) lithography. These advances demonstrate that resists for wide application can be designed from a common platform of materials technology. 

One type of proximity effect—the interproximity effect—involves the exposure of features near the ones that are intentionally q>osed, referred to as near neighbors. Une q)osed spaces between lines are exposed by backscattered electrons. This effect is seen in the work performed for this study. The interproximity effect causes unexposed spaces in positive resists to become thinner and narrower. For negative resists, such as ours, the unexposed region is filled with scumming resist. 

The resist must have suitable radiation sensitivity. Today s exposure tools are so costiy that tool throughput is a key measure of performance. The overall time to expose a resist film is the sum of the times to load and position the substrate in the exposure tool, to align the substrate and the mask, to irradiate the film, and to unload the complete part. In the optimum case the resist exhibits sufficient radiation sensitivity so that the fraction of the overall cycle apportioned to irradiate the film does not limit the number of substrates exposed in a given period of time. 

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