A strong demand exists for techniques that can further extend the application of ArF immersion lithography. Besides
techniques like litho-friendly design, dual exposure or patterning schemes, customized illumination modes, also
alternative processing schemes are viable candidates to reach this goal. One of the most promising alternative process
flows uses image reversal by means of a negative tone development (NTD) step with a FUJIFILM solvent-based
developer. Traditionally, the printing of contacts and trenches is done by using a dark field mask in combination with
positive tone resist and positive tone development. With NTD, the same features can be printed in positive resist using a
light field mask, and consequently with a much better image contrast.
In this paper, we present an overview of applications for the NTD technique, both for trench and contact patterning,
comparing the NTD performance to that of the traditional positive tone development (PTD). This experimental work was
performed on an ASML Twinscan XT:1900i scanner at 1.35 NA, and targets the contact/metal layers of the 32 & 22 nm
node. For contact hole printing, we consider both single and dual exposure schemes for regular arrays and 2D patterns.
For trench printing, we compare the NTD and PTD performance for one-dimensional patterns, line ends and twodimensional
structures. We also assess the etch capability and CDU performance of the NTD process.
This experimental study proves the added value of the NTD scheme. For contacts and trenches, it allows achieving a
broader pitch range and/or smaller litho targets, which makes this process flow attractive for the most advanced
lithography applications, including double patterning.