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New resist systems based on acid‐catalyzed, electrophilic aromatic substitution are described. These new resists show high sensitivity to deep UV and E‐beam radiation with values approaching 2 mJ/cm2 and 2 μC/cm2, respectively. The resists are based on a three component system consisting of poly(4‐hydroxystyrene), a polyfunctional, low molecular weight, latent electrophile, and a photoactive onium salt used as an acid generator. Irradiation of the resist film produces a latent image of acid dispersed in the matrix. During the postbaking step the photo‐generated acid reacts with the latent polyfunctional electrophile and releases a reactive carbocationic intermediate with concomitant liberation of acetic acid. The carbocationic intermediate then reacts with neighboring phenolic moieties in a crosslinking reaction. The substitution reaction liberates a proton, making the process catalytic in nature, thus incorporating the concept of chemical amplification. These highly sensitive materials can be used as nonswelling negative multipurpose resists that function in deep‐UV, x‐ray or E‐beam modes. © 1993 John Wiley & Sons, Inc.

The advent of deep-UV (DUV), chemically amplified, acid catalyzed photoresists as successors to positive diazoquinones photoresists has brought about a new set of process environment concerns directed towards all materials in contact or absorbed by the photoresists. In addition to the application of DUV bottom anti-reflective coatings (BARCs) to suppress optical reflection and subsequent linewidth distortion, we must consider the properties and interaction of the BARC layer with the labile photoacid of the latent image. In this regard, we have examined the physico-chemical aspects of the DUV BARC with regards to acting as a barrier layer to substrate poisoning, and as an optical absorbing layer that does not interact and/or distort the deep-UV profile. Various single component polymeric BARCs were synthesized and examined. Considerations will be discussed of the optical absorbance, the coating quality, dry etch rate, and the impermeability of the BARC layer to photoacid diffusion to fulfill the performance requirements of BARCs for DUV lithography.

Microbridge formation in a CAlViN photoresist we have developed is dependent on the ratio of dose to print ( DiP ) to dose to gel ( DTG ) as well as resist contrast. Photoresists formulated with poly(p-hydroxystyrene) (PHS) have a very high tendency to form microbridges when developed in 2.38 wt% TMAH due to high contrast and high a DTP/DTG ratio. When photoresists formulated from PHS were developed in 1 .2 wt% TMAH contrast and DTP/DTG ratio were reduced resulting in microbridging being nearly eliminated. Using this observation we developed an I-line CAMN photoresist with PHS type thermal stability and high resolution capabilities which can be developed in industry standard 2.38 wt% TMAH.

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