Tip based chemical vapor deposition of silicon

Electric-field assisted decomposition of gas molecules such as SiCl₄ and SF₆ was used near a conducting AFM tip to directly deposit, etch and pattern nanometer-scale silicon structures. Deposition required around + 50 MV/cm (~+30 V) while etching could be achieved at lower fields around -10 MV/cm (~-10 V) with the voltage as applied to the tip. This technique is versatile and can deposit/pattern dielectrics and metals as well by using appropriate pre-cursor gases. The deposition/etching time is around tens of seconds/μm³ and it can be improved employing parallel probes. The spatial resolution is primarily determined by tip size, gas mean-free path and random walk of the tip over the sample (tip actuator noise). Features as small as 1 nm are achievable at one atmosphere at room temperature and 60 nm features with 60 nm are routine under these conditions.