森田 昇

In order to fabricate a nanoscale three-dimensional (3D) structure by using the ion-beam lithography (IBL), we tried to control the etching rate and the etching depth by means of the charge state, the beam energy, and the fluence of the ion beam. Ar-ion beams with E=90 keV and 80-400 keV were irradiated onto spin on glass (SOG) and Si, respectively. The Ar ions were prepared by a facility built at the Kochi University of Technology, which included an electron cyclotron resonance ion source (NANOGAN, 10 GHz). It was found that the irradiation of highly charged ions (HCIs) enhanced the etching rate of SOG. The etching rate and etching depth of Si were controlled by the beam energy and the fluence of Ar4+ ions. The present results show the effectiveness of IBL with HCIs to fabricate a nanoscale 3D structure. ? 2006 American Institute of Physics.

This study proposes a novel method of nano-scale patterning on a metallic glass surface using focused ion beam (FIB) irradiation followed by wet chemical etching. We found that etch rate of a metallic glass surface irradiated with Ga+ion beam can be drastically changed, and rapid patterning is possible utilizing this method. Cross-sectional transmission electron microscopy (TEM) analysis reveals that the metallic glass substrate remains amorphous phase after the irradiation. In addition, etching enhancement does not shown at the irradiation of Ar+ions. Thus, these results indicate that the etching enhancement is resulted from the existence of implanted Ga+ion rather than the change in crystallization.

Etching characteristics of a silicon surface irradiated by high-energy ion beam against HF are investigated in this study. Specially designed ion irradiation facility, which enables to irradiate high-energy ion beam, is employed. A deep structure with a depth of several hundreds nanometers can be fabricated by utilizing high-energy ion irradiation. The depth of irradiated area can be controlled by adjusting acceleration voltage and ion charge, and it is related to distribution of damaged layer induced by ion irradiation. These results indicate a possibility of application as a novel deep three-dimensional nanofabrication process.

To achieve rapid patterning of quartz surface, ion beam irradiation using focused ion beam (FIB) and succeeding buffered hydrofluoric acid wet etching of quartz was examined. The etched depths of quartz saturated with increasing of ion dose and the optimum wet etching time was 60 s. This process improved surface roughness and fabricated a 34 nm depth and 487 nm width line pattern using 330 nm diameter FIB irradiation.

A simple process to fabricate a three-dimensional structure on silicon surface was developed by using tribo-nanolithography (TNL) in an aqueous KOH solution. An inclined rectangular structure can be fabricated by a process where a thin amorphous layer, having corrosion resistance against KOH, rapidly forms on the substrate at the diamond tip sample junction along the scanning pass of the tip, while simultaneously, the area not covered with the amorphous layer is being etched in KOH. An inclination of structure can be controlled by the scanning velocity. The scanning pitch is related to the corrosion resistance of the amorphous layer, rather than the change of inclination. We fabricated a structure having multiple inclinations based on these results, which indicates the possibility of using the TNL for three-dimensional nanofabrication. ? 2005 American Vacuum Society.

Tribo-nanolithography (TNL) can form an affected layer on a silicon surface that is resistant to corrosion by KOH, and a nanostructure can be fabricated by combination with wet chemical etching. Transmission electron microscope (TEM), Auger electron spectroscopy (AES) and secondary ion mass spectrometry (SIMS) analyses were utilized to investigate the mechanism of the etch stop effect on the machined area. TEM observation revealed that the silicon crystal structure was converted to an amorphous structure measuring approximately 15-20 nm. AES and SIMS analyses indicated that the amorphous layer consisted entirely of silicon. Thus, the mechanism of the etch stop effect on the machined area was determined to result from the formation of an amorphous silicon structure. ? 2005 IOP Publishing Ltd.

This study is intended to fabricate 3D microstructures on single crystal silicon by tribo-nanolithography (TNL) and wet chemical etching. In previous report, it could be known that height of microstructure fabricated by the TNL and subsequent wet chemical etching can be controlled by adjusting the TNL conditions such as normal load, pitch of processing line and number of processing. This paper reports an etch result by HF solution in order to evaluate the mechanism of height change with the TNL conditions. As a result, it is found that amorphous layer formed by the TNL can be selectively etched in HF solution though non-processed area withstands etching. The mechanism of change of masking effect is evaluated by utilizing this phenomenon. As a result, it can be known that change of masking effect by normal load is resulted from change of thickness of the amorphous layer. On the other hand, those by pitch of processing line and number of processing are resulted from conversion ratio of single crystal to amorphous structure.

This study is intended to fabricate 3D microstructures on single crystal silicon by tribo-nanolithography (TNL) and wet chemical etching. The processed area of single crystal silicon by diamond tip withstands etching in KOH solution, and consequently protruding microstructure can be fabricated. Transmission electron microscope (TEM), Auger electron spectroscopy (AES) and secondary ion mass spectrometry (SIMS) analyses are utilized to study the mechanism of masking effect. As a result, it can be known that crystal silicon structures are converted to amorphous silicon by TNL process, resulting in acting to the etch mask against KOH solution. Comparison of etch rate between amorphous and single crystal silicon is conducted. In addition, mechanism of protuberance, which is generated in processing under lower normal load, is studied with minute observation of processed area.

A simple process to fabricate 3 D microstructures on single crystal silicon is presented in this study. The area irradiated by focused ion beam (FIB) can be selectively etched in HF solution. Etching characteristics of irradiated area are studied. The etch rate of irradiated area increases with increasing dose over 3.4 × 10-5C/cm2. In addition, it can be also controlled by accelerate voltage. Subsequently, it is etched by KOH solution in order to evaluate the mechanism of this phenomenon. Dependence of surface roughness on dot pitch is evaluated. Finally, 3 D microstructures can be fabricated based on these results, which indicates a possibility of industrial application as a novel 3 D micro-fabrication process.

This study aims to fabricate three dimensional nanostructures of single crystal silicon by focused ion beam (FIB) process and subsequent wet chemical etching. Irradiated area by FIB acts as a mask against KOH solution, and consequently protruding nanostructures having several hundreds of nanometers in height can be fabricated through etch process. In order to control the height of nanostructures, the dependence of the masking effect on FIB irradiating conditions are studied under various parameters. As a result, it is found that the masking effect can be controlled by FIB irradiating conditions such as dose, accelerate voltage and dot pitch. Finally, three dimensional nanostructures can be fabricated based on these results, which indicates a possibility of industrial application as a novel three dimensional nanofabrication process.