Probe with embedded heater for nanoscale analysis
The invention is a heated thermal probe suitable for use in micro-thermal analysis or other high resolution thermal measurements and actions. The probe is, in the preferred embodiment, a microfabricated cantilever with a sharp probe tip of a type used in Scanning Probe Microscopes (SPM's) which further includes an integral resistive heating element. The heating element is formed by doping regions of the cantilever with an ion implant process to make lower resistance connections and a higher resistance heating element. There is no spatial overlap between the base of the probe tip and the heating element or conductors.
1. A microfabricated thermal probe, comprising;
a substrate,
a cantilever comprising a fixed end at the substrate and a planar surface extending from the substrate to a free end opposite the fixed end,
a sharp probe tip, located at least substantially at the free end of the cantilever, the probe tip having a base that is coplanar with the planar surface of the cantilever the probe tip extending out and away from the plane of the planar surface of the cantilever to a sharp end,
at least two separate electrically conductive traces formed by an implant process on the cantilever; and,
at least one heating element with an active area, formed by an implant process on the cantilever, electrically connected to and bridging the traces, wherein;
there is no spatial overlap between the base of the probe tip and the active area of the heating element,
the active area of the heating element is located at the free end of the cantilever and adjacent to the tip and heats the tip; and,
the resistance of the heating element is greater than twice the resistance of the traces.
2. The cantilever of claim 1 comprising a single lever arm.
3. The cantilever of claim 1 comprising two lever arms joined by a cross piece between the arms at or near the free end, wherein each arm is implanted to form a conductive trace, and the probe tip base and heating element are carried on the cross piece.
4. The probe of claim 1 wherein the probe tip length from base to end is greater than 3 microns.
5. The probe of claim 1 wherein the probe tip length is between 3 and 15 microns.
6. The probe of claim 1 wherein the heating element is greater than 90% of the total electrical resistance of a circuit formed from the traces and the heating element.
7. The probe of claim 1 wherein the total electrical resistance of the trace-heating-element circuit a circuit formed from the traces and the heating element is between 50 Ohms and 50 kohms.
8. The probe of claim 7 wherein the total electrical resistance of a circuit formed from the traces and the heating element is between 400 Ohms and 8 kohms.