Fullerene Resist Materials for the 32 nm Node and Beyond

Abstract

Current resist materials cannot simultaneously meet the sensitivity, resolution and line width roughness (LWR) requirements set out by the International Technology Roadmap for Semiconductors (ITRS) for the 32nm node and beyond. Here we present a fullerene‐based, chemically amplified resist system, which demonstrates the potential to fulfill these requirements for next generation lithography. A chemically amplified fullerene resist was prepared, consisting of the derivative MF07‐01, an epoxide crosslinker, and a photoacid generator, such as triarylsulfonium hexafluoroantimonate. The sensitivity of this resist was shown to be between 5 and 10 µC cm−2 at 20 keV for various combinations of post‐application bake and post‐exposure bake conditions. Using 30 keV electron beam exposure, sparse patterns with 15 nm resolution were demonstrated, whilst for dense patterns a half‐pitch of 25 nm could be achieved. The LWR for the densely patterned features is ∼4 nm. The etch durability of the fullerene CA system was shown to be comparable to that of SAL601, a common novolac‐based commercial resist, at almost four times that of silicon.

Towards novel non-chemically amplified (n-CARS) negative resists for electron beam lithography applications

“…18,19 More recently, the Robinson group developed a fullerene based chemically amplied e-beam resist and reported good sensitivity, resolution, LWR $ 4 nm and higher etch resistance comparable to the commercially available SAL601 resist. [20][21][22][23] While comparing the performances of the reported efficient resists, we found that our newly developed resist possesses improved sensitivity compared to some of the reported values (Table S2, ESI †). New inorganic resists with Zr and Hf for e-beam lithography have demonstrated, using a 30 keV electron-beam, 24,25 sensitivities as low as 8 mC cm À2 , achieved 15 nm lines and 36 nm dense features at higher doses with approximately 2 nm of LWR.…”

Negative tone molecular resists using cationic polymerization: Comparison of epoxide and oxetane functional groups

“…They have very high resolution and good LER, 3,4 but significantly worse sensitivity than would be considered useful for modern high volume sub-0.25-m commercial semiconductor fabrication. Molecular resists based on cross-linked fullerenes have shown excellent results under e-beam imaging, [13][14][15][16][17] and a few other reports of cross-linking calixarene resists have also shown good performance. By increasing photoacid diffusion, sensitivity is improved, but resolution is lost due to diffusion of the photoacid outside of the nominally exposed areas.…”

Chemically amplified fullerene resists for e-beam lithography

“…More recently a change in the crosslinking component allowed the patterning of features with 15 nm sparse pattern linewidths and 25 nm half pitch (hp) dense features, whilst maintaining the high sensitivity and durability. 29 Here we present the results of further optimization of the crosslinking component, leading to even higher resolution, together with characterization of the process latitude of the resist. The fullerene derivative, shown in figure 1(a), and the photoacid generator, shown in figure 1(b) were used in both resist compositions discussed.…”