Smart nano-machining and measurement system with semiconductive diamond probe

Abstract

We have developed an ultraprecision machining system with an in situ STM function. For this purpose, we have made a semiconductive diamond probe of sufficient hardness to prevent deformation or damage occurring during machining and with a tunnel-current-detecting capability for the fabrication of three-dimensional nano-structures in any material, independent of hardness. In order to realize this system, we first constructed a high-resolution driving system with two single-tube three-dimensional piezoelectric devices as scanners. Test measurements with a conventional tungsten probe showed that this driving system could obtain STM images with a resolution of about 20 nm. Next, we developed a CVD molding technique for fabrication of the semiconductive diamond probe. A mold with a 70 µm × 70 µm square pyramidal pit was formed by anisotropic etching of (001)Si in potassium hydroxide (KOH) solution. Then, a semiconductive diamond thin film was deposited onto the pyramidal mold using hot-filament CVD. After removing the mold by wet etching, the resulting pyramidal diamond probe had a facial angle of 70.6 • and a tip radius of about 70 nm. In order to test the applicability of this semiconductive diamond probe, we machined polished Si (a typical hard-to-cut material) to form nano-scale grooves and square recesses, and then measured those machined structures in situ using the three-dimensional driving system. The results showed that this newly developed semiconductive diamond probe was effective both as a machining tool and as an STM probe.

The use of active materials for machining processes: A review

“…Properly installed, the smart disc-based damping system can reduce the amplitude of the dominant vibration mode by 86% and greatly enhances the line-width precision of circuit patterns for integrated circuit manufacturing. Unno et al [105] also used a pair of piezoelectric tube-type stack actuators to construct a high-resolution driving system for a semi-conductive diamond probe used in nano-scale machining. This driving system demonstrated a resolution of approximately 20 nm.…”

Implementation of cross-scale plane micro-scratching process driven by hybrid piezoelectric actuation

“…The use of diamond with extreme mechanical hardness and wear resistance as a probe material is expected to eliminate the problem [32,33]. Several studies of micro/nano fabrication using diamond tips have been reported [34][35][36]. However, machining in the depth range of sub-micrometer has not been investigated owing to the low lever stiffness.…”

Fabrication and Characterization of AFM Probe Integrated with High-Aspect-Ratio Diamond Tip

“…In our previous work, we also demonstrated the superiority of semiconductive pyramidal diamond tips for scanning tunneling microscope (STM) as well as a machining tool [6] and diamond AFM probes consisting of a V-shaped diamond cantilever integrated with a pyramidal diamond tip [7][8][9]. However, further improvement in the diamond tip feature is required to achieve the measurements and nanomachining of samples with a high aspect ratio feature or steep sidewall like narrow and deep trenches.…”