Lithographically Formed Carbon Nanotube Structure Provides Pressure Connections for Device Under Test

A carbon nanotube contact structure can be used for making pressure connections to a device under test (DUT). The contact structure can be formed using a carbon nanotube film or with carbon nanotubes in solution. The carbon nanotube film can be grown in a trench in a sacrificial substrate in which a contact structure such as a beam or contact element is then formed by metal plating. The film can also be formed on a contact element and have metal posts dispersed therein to provide rigidity and elasticity.

Contact structures or portions thereof can also be plated with a solution containing carbon nanotubes. The resulting contact structure can be tough, and can provide good electrical conductivity, according to inventors Formfactor Inc Chief Technology Officer Benjamin N. Eldridge, John K. Gritters, Igor Y. Khandros, Rod Martens and Gaetan L Mathieu in U.S.  Patent Application 20100112828

Carbon nanotubes have received attention based upon their extremely small size, high strength and excellent electrical and thermal conductivity characteristics. However, challenges arise when working with carbon nanotubes. For example, a film of aligned carbon nanotubes has electrical connectivity throughout the film. But each carbon nanotube may act independently, and the film deforms plastically. The film does not have the rigidity and elasticity desired for test interconnection elements or contact structures to form a positive connection to a device under test. 

 The invention provide contact elements for a probe, which is also referred to herein as a contact structure. The contact elements, or the entire probe, may be made from carbon nanotube structures that have carbon nanotubes incorporated therein in a variety of ways. In one aspect, the carbon nanotubes may be grown on a film in a trench in which components of the probe are lithographically formed.

In another aspect the carbon nanotubes may be in a plating solution that is used to plate a probe or a probe contact element. In still other aspects, the entire probe or contact element may substantially comprise carbon nanotubes. In implementations that include carbon nanotube films, the films may be patterned to provide areas in which metal is formed to resist plastic deformation of the carbon nanotubes.