What is claimed is:
1. A micro-hotplate device which comprises:
a support substrate;
a microbridge structure formed on said support substrate, said microbridge structure having a suspended portion;
a heating element formed directly on said microbridge structure so as to be thermally isolated from said support substrate;
a layer of electrically insulating material formed directly on said heating element; and
a conductive heat distribution plate formed directly on said layer of electrically insulating material, said conductive heat distribution plate being centrally located over said microbridge structure.
2. A micro-hotplate according to claim 1, wherein said conductive heat distribution plate includes four leads for sensing temperature.
3. A micro-hotplate according to claim 1, wherein the microbridge structure comprises a layer of electrical insulation material.
4. A micro-hotplate according to claim 3, wherein a central portion of the microbridge structure is suspended over an etch pit which is formed in the substrate support.
5. A micro-hotplate according to claim 4, wherein said etch pit is formed with a closed bottom.
6. A micro-hotplate according to claim 3, wherein a central portion of the microbridge structure is suspended over an etch pit which has a closed bottom.
7. A micro-hotplate according to claim 1, further comprising a layer of an electrical insulating material formed on a side of the conductive heat distribution plate which side is opposite to a side thereof which faces said heating element.
8. A micro-hotplate according to claim 7, further comprising a plurality of contact pads which are formed on said layer of electrical insulating material.
9. A micro-hotplate according to claim 8, wherein said contact pads are covered with another layer of an electrical insulating material which includes through holes that allow portions of the contact pads to be exposed through said another layer of electrical insulating material.
10. A micro-hotplate according to claim 8, wherein said contact pads include electrical leads.
11. A micro-hotplate according to claim 8, wherein said contact pads comprise aluminum.
12. A micro-hotplate according to claim 1, wherein said micro-hotplate has a size of between about 2.5.times.10.sup.3 and 6.4.times.10.sup.5 square microns.
13. A micro-hotplate according to claim 1, wherein said support substrate comprises silicon.
14. A micro-hotplate according to claim 13, wherein said silicon support substrate comprises a silicon wafer or chip.
15. A micro-hotplate according to claim 1, wherein said heating element comprises polysilicon.
16. A micro-hotplate according to claim 1, wherein said conductive heat distribution plate comprises aluminum.
17. An array of micro-hotplate devices which comprises:
a support substrate;
a plurality of microbridge structures formed on said support substrate, each of said plurality of microbridge structures having a suspended portion;
individual heating elements formed directly on each of said plurality of microbridge structures so as to be thermally isolated from said support substrate;
a layer of electrically insulating material formed directly on each of said heating elements; and
individual conductive heat distribution plates formed directly on said layer of electrically insulating material above each heating element and located centrally over an underlying microbridge structure.
18. A method of making a micro-hotplate device which comprises:
providing a support substrate having a first layer of an insulating material;
designing said first layer of insulating material into opening portions and a bridge portion;
removing the first layer of insulating material from said opening portions;
forming a heating element directly on said bridge portion;
forming a second layer of insulating material directly on said heating element;
forming a conductive heat distribution plate directly on said second layer of insulating material, said conductive heat distribution plate being located centrally over said microbridge structure;
forming a third layer of insulating material on said conductive heat distribution plate; and thereafter,
etching out a portion of said support substrate beneath said bridge portion through said opening portions so as to suspend and thermally isolate said bridge portion from said support substrate.
19. A method of making a micro-hotplate device according to claim 18, further comprising forming four leads which are connected to said conductive heat distribution plate.
20. A method of making a micro-hotplate device according to claim 18, further comprising, prior to said etching step, forming a plurality of contact pads on said third layer of insulating material; and forming a fourth layer of insulating material on said contact pads, with through holes therein which allow portions of said contact pads to be exposed through said fourth layer of insulating material.
21. A micro-hotplate device which comprises:
a support substrate;
a microbridge structure formed on said support substrate;
a heating element formed on said microbridge structure so as to be thermally isolated from said support substrate; and
a conductive heat distribution plate formed above said heating element, said micro-hotplate made by:
providing a first layer of an insulating material on said support substrate;
dividing said first layer of insulating material into opening portions and a bridge portion;
removing the first layer of insulating material from said opening portions;
forming said heating element directly on said bridge portion of said first layer of insulating material;
forming a second layer of insulating material directly on said heating element;
forming said conductive heat distribution plate directly on said second layer of insulating material, said conductive heat distribution plate being located centrally over said bridge portion;
forming a third layer of insulating material on said conductive heat distribution plate; and thereafter,
etching out a portion of said support substrate beneath said bridge portion through said opening portions so as to suspend and thermally isolate said bridge portion from said support substrate.
22. A micro-hotplate according to claim 21, wherein said conductive heat distribution plate includes four leads for sensing temperature.
23. A micro-hotplate according to claim 21, further comprising a plurality of contact pads which are formed on said third layer of insulating material.
24. A micro-hotplate according to claim 23, wherein said contact pads are covered with another layer of an electrical insulating material which includes through holes that allow portions of the contact pads to be exposed through said another layer of electrical insulating material.
25. A micro-hotplate according to claim 23, wherein said contact pads include electrical leads.
26. A micro-hotplate according to claim 23, wherein said contact pads comprise aluminum.
27. A micro-hotplate according to claim 21, wherein said micro-hotplate has a size of between about 2.5.times.10.sup.3 and 6.4.times.10.sup.5 square microns.
28. A micro-hotplate according to claim 21, wherein said support substrate comprises silicon.
29. A micro-hotplate according to claim 28, wherein said silicon support substrate comprises a silicon wafer or chip.
30. A micro-hotplate according to claim 21, wherein said heating element comprises polysilicon.
31. A micro-hotplate according to claim 21, wherein said conductive heat distribution plate comprises aluminum.