森田 昇

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.

The TNL (Tribo Nanolithography) method in aqueous solution uses the atomic force microscopy as a machining tool for the nanoscale fabrication of silicon. A specially designed cantilever with a diamond tip allows the formation of oxide patterns easily by a simple scratching process. A rectangular structure with a slope can be fabricated by a process in which a thin oxide layer rapidly forms in the substrate at the diamond-tip sample junction along the scanning path of the tip, and, simultaneously, the area uncovered with the oxide layer is being etched. Etching in KOH and HF is conducted to verify corrosion characteristics of oxide.

The TNL (Tribo Nanolithography) method in aqueous solution uses the atomic force microscopy as a machining tool for the nanoscale fabrication of silicon. A specially designed cantilever with a diamond tip allows the formation of oxide patterns easily by a simple scratching process. A rectangular structure with a slope can be fabricated by a process in which a thin oxide layer rapidly forms in the substrate at the diamond-tip sample junction along the scanning path of the tip, and, simultaneously, the area uncovered with the oxide layer is being etched. Etching in KOH and HF is conducted to verify corrosion characteristics of oxide. Copyright ? 2004 by ASME.

The tribonanolithography (TNL) of silicon substrate in aqueous solution based on the use of atomic force microscopy (AFM) was investigated. A cantilever with a diamond tip, which allowed the formation of a protruding oxide layer several nanometers high using a simple machining process with a given pitch, was used for TNL process in KOH solution. The stopping of anisotropic wet etching was observed in the modified area as silicon oxide was found to be resistant to corrosion by KOH. The results confirm the possibility of the fabrication of a three-dimensional slant nanostructure by taking advantage of the time lag of oxide formation during etching in KOH solution.

This study proposes a new method on 3 D micro fabrication using a combination technique of nano-scale processing and wet chemical etching. The (100) surface of single crystal silicon was processed by using the mechanism of friction force microscope (FFM). A processed area was protuberated in the condition where normal load is less than 372 μN. The sample processed in this condition was etched by KOH solution. After the etching process, convex structure was made on processed area. The effect of processing condition on etch rate of processed area was studied. It was found that etch rate was changed with normal load, pitch of processing line and number of processing. Also, mechanism of height change was investigated under those conditions and some 3 D microstructure were fabricated by these results.

This study proposes the 3D micro-fabrication method on single crystal silicon using a focused inn beam (FIB) process with masking effect for chemical etching. It could be seen that the area processed by FIB remains though it was etched by KOH solution. The dependence of the masking effect on experimental conditions and its mechanism were studied by various parameters and structural analysis respectively. Some attempts to fabricate 3 D micro-structures were made based on these results. Subsequently, the costs can be decreased to fabricate 3 D micro-structure and the process be simplified compared to that using a traditional photoresist-masking method, owing to the simple sequential processes of the chemical etching followed by FIB process.