Sub Micron Cleaning of Microelectronic Devices

The microelectronics industry is facing a multitude of challenges regarding device cleaning. New challenges include increasingly delicate features, tighter offsets and the removal of lead free compounds. The standard for wet cleaning has been atmospheric immersion clean using an appropriate chemistry. In certain cases sonic energy is used to remove particles. The effectiveness of these techniques is now in question.

Vacuum Cavitational Streaming (VCS) provides an alternative for the removal of sub-micron particulate contaminates and residue with minimal to no damage to surfaces and/or critical part features. With VCS an alternative to mechanical and/or acoustic streaming is now available. Recent testing has shown high efficiency removal of .15 to .01 micron particulate contaminate from planar, via and porous part surfaces. With VCS, cavitation bubbles are grown on nucleation sites (particles- contaminates-imperfections).

As the vacuum pressure modulates the cavitation stream of bubble growing and imploding is generated. As the imploding bubbles release their stored energy directly onto the surfaces, Van Der Val forces-Zeta potential are disturbed releasing particulate contaminates, which are immediately removed from the vacuum chamber. VC Streaming continues until the desired level of cleanliness is achieved.

Damage to surfaces is highly unlikely due to the very nature of the principles of nuclear boiling, because bubbles only grow (nucleate) ON surfaces where particles and contaminates are present. Nucleation sites (bubble growth) will not occur on clean surfaces. Redeposit of particulate contaminates is also eliminated due to the immediate removal of dislodged particulate contaminates. VCS is dependent upon energy transfer of surfaces making difficult to reach areas such as porous surfaces, vias and patterned, as well as planar surfaces, excellent candidates for this unique technology.

VCS has an added benefit of taking place in an "airless" environment which now provides a means of cleaning those surfaces that tend to form oxides, i.e. low-k copper. The VCS method of cleaning is integrated with vacuum drying all within a single vacuum chamber where the environment is controlled and managed with vacuum to achieve sub micron clean and dry performance previously not available.