Search

Background: The homogeneity of photoacid generator (PAG) is a critical factor influencing the resolving capability and the sidewall roughness of a photoresist, yet fundamental understanding of the PAG homogeneity lacks at the nanoscale. Aim: We present a methodology, massive cluster secondary ion mass spectrometry (MC-SIMS), to determine PAG homogeneity on a 10- to 15-nm scale at the photoresist film surface. Approach: MC-SIMS bombards the sample with a sequence of massive Au400 + 4 nanoprojectiles, each separated in time and space, collecting and mass analyzing the coemitted secondary ions from each impact. Each sample is analyzed with one million individual projectile impacts. Analysis of coemission of these independent more than one million mass spectra allows for identification of colocalized molecules within nanodomains ∼10- to 15-nm diameter and ∼10 nm in depth from the film surface, therefore revealing spatial molecular distributions at the nanoscale. Results: About 85% to 95% of the measurements showed PAG–PAG coemission and over 90% showed polymer–PAG coemission. Ion-exchanging additive increases polymer–PAG coemission. Conclusions: The majority of PAG molecules exist as small aggregates that are

We describe a methodology for nanoscale molecular analysis and present its capabilities. The analysis method is based on secondary-ion mass spectrometry with gold nanoparticles (e.g., Au4004+). The methodology presented has unique features that enable nanoscale molecular analysis, namely the method of acquiring the mass spectrum and the nature of the impacting projectile. In the method, a sequence of individual gold nanoparticles (Au4004+) is used to bombard the sample; each impact results in ion emission from an area ∼10–20 nm in diameter. For each of impact of Au4004+, the emitted ions are mass analyzed by time-of-flight mass spectrometry, detected and stored together in one mass spectrum prior to the arrival of the subsequent projectile. Each mass spectrum contains elements and molecules, which are colocalized within ∼10 to 20 nm of one another. Examination of the coemitted ions allows us to test the molecular homogeneity and chemical composition at the nanoscale. We applied this method to a chemically amplified resist before and after exposure and development. After development the method was used to chemically characterize defect sites that were not removed by the developing solution.

We describe a novel deterministic bottom-up/top-down approach to sub-30-nm photolithography using a film composed of assembled block brush polymers of highly uniform composition and chain length. The polymer architecture consists of a rigid backbone of polymerized norbornene, each linked to flexible short side brush chains. The resultant bottle brush topology has a cylindrical shape with short brush chains arranged concentrically around the backbone, in which the cylinder radius is determined by the number of monomers within the brush fragment, while the cylinder length is determined by the degree of backbone polymerization. The modularity of the synthetic system allows a wide diversity of lithographically useful monomers, sequencing, dimension, and property variation. Sequential grafting of presynthesized blocks allows for facile formation of either concentric or lengthwise block copolymers. Placement of brush chains of different compositions along different regions of the cylinder, along with variation of the relative concentric and lengthwise dimensions, provides mechanisms to align and control placement of the cylinders. These polymers are compatible with photoacid generators and crosslinker functionality. Our results are consistent with a model that the bottle brush polymers assemble (bottom-up) in the film to yield a forest of vertically arranged cylindrical block brush polymers, with the film thickness determined by the coherence lengths of the cylinders. Subsequent imaging via electron beam (e-beam) or optical radiation yields a (top-down) mechanism for acid catalyzed crosslinking of adjacent cylinders. Uncrosslinked cylinders are removed in developer to yield negative photoresist patterns. Exposure doses are very low and throughputs are amenable to the requirements of extreme ultraviolet lithography. The limiting resolution with e-beam exposure is potentially about two cylinder diameters width (