Fabrication of ultra-sharp tungsten tip using electro-chemical etching system

전기화학적 에칭방법을 이용한 초미세 바늘 전극 제작

To obtain the ultra-sharp tungsten tip, an analog to digital converter circuit aided by a personal computer has been setup. At the moment the lower part of the needle drops off during the etching process, a maximum current change across the reference resistor is detected by the PC interface card and the applied voltage is then cut off within a few milliseconds. Out experiment has been able to fabricate an ultra-sharp tungsten tip ~200 $\AA$ radius with a higher reproduction rate and reliability than the conventional method.