| Summary: | 碩士 === 國立清華大學 === 電子工程研究所 === 92 === The transistor has evolved into the nanoscale device. The most common form is a simple switch the field effect transistor (FET). The modern FET qualifies as a nanoscale device since the length of the gate region is only 90nm .The FET has slowly evolved through improvement in optical lithography. We all await the technology set that will push these devices below the classical limits and on to the world of devices that relies on the quantum behavior of electrons. That transition will take place when the device dimensions are reduced below 50nm. It is a world beyond the reach for optical lithography. Devices with these dimensions will require a revolutionary change in the fabrication process.
Scanning Tunneling Microscope (STM) not only the observed tool, but also have a lot of application. In this paper, we use STM for fabrication nanoscale structures. It’s also called SPM nanolithography. The paper divided into two parts: (1) Using the STM tip to oxidize metal (Ti) film in the atmosphere. Appling the positive pulse to the
sample, and the position of tip will have oxide growth. This oxidation process is Field-induced oxidation. After the field-induced oxidation of titanium, and remove the
unoxidation regions by 5% HF. The titanium dioxide become the metal mask, likes the positive photoresist in optical lithography. And we discus the structure with oxidation parameter ;(2) Using the mica coating with 200nm gold film, and let STM tip covered with copper atom. The interaction between copper and gold is stronger than the interaction between copper and copper. By a little mechanical contact
(jump-to-contact), the copper atoms will stay on the gold surface.
No matter in atmosphere (oxidation) or solution (reduction) system. We can get nano-structure under the size control, distribution control and position control by STM. SPM nanolithography can applied for difference environments and substrate.
Not only can observe the phenomenon in nanoscale, but also provide a powerful tool for the nanodevice fabrication.
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