Invited Paper MS-ThM3
The Helium Ion Microscope and Applications for Semiconductor Manufacturing and Characterization

Thursday, October 18, 2007, 8:40 am, Room 615

ALIS Corporation (a Carl Zeiss SMT company) has developed a helium ion microscope which provides high resolution images with strong contrast mechanisms. Although technically a focused ion beam (FIB) the microscope operates more like a scanning electron microscope (SEM) but with higher resolution and stronger contrast. The technology and its general capabilities are being presented in another session. This paper addresses some of the semiconductor manufacturing applications which are well suited to the helium ion microscope. Process development and process monitoring require high resolution imaging and contrast mechanisms that are sensitive to material differences. The helium ion microscope is well suited to these tasks. In particular, the secondary electron images can reveal fine details which contain topographic or material information. Grain formation is evident through well established channeling contrast mechanisms. Electrical properties can be revealed by virtue of the beam induced voltage contrast effects. Images can also be generated from the scattered helium ions, providing the ability to distinguish different materials based on their atomic number. This also has the advantage of giving a resolution which is superior to the presently used EDX analysis. Testing has been conducted to look for any effects of damage to semiconductor devices. In particular, a series of tests were conducted to examine any possible effect on the transistor turn on voltages, Vt, after various exposures to helium ions. Test results show no measurable shift. Higher dosages have been tested to look for other signs of damage. Additional manufacturing applications will be presented.