Heater design for heat-trimmed thin film resistors
View Patent ↗A heater design for post-process trimming of thin-film transistors is described. The heater incorporates low sheet-resistance material deposited in non-active connecting regions of the heater to reduce heat generation and power consumption in areas distant from active heating members of the heater. The heating members are proximal to a thin-film resistor. The resistance of the thin-film resistor can be trimmed permanently to a desired value by applying short current pulses to the heater. Optimization of a heater design is described. Trimming currents can be as low as 20 mA.
1. A heat-trimmable resistor comprising:
a thin-film resistive element configured as a resistor that is connected to or connectable to a circuit;
a thin-film heating region proximal at least a portion of the thin-film resistive element; and
an electrically-conductive material in electrical contact with the thin-film heating region and having lower sheet resistance than the thin-film heating region that connects the thin-film heating region to a conductive interconnect.
2. The heat-trimmable resistor of claim 1 incorporated in an integrated circuit.
3. The heat-trimmable resistor of claim 1 , wherein the thickness of the electrically-conductive material is greater than the thickness of the thin-film heating region.
4. The heat-trimmable resistor of claim 3 , wherein the thickness of the electrically-conductive material is greater than about 10 nm.
5. The heat-trimmable resistor of claim 3 , wherein the thickness of the electrically-conductive material is greater than about 50 nm.
6. The heat-trimmable resistor of claim 1 , wherein the electrically-conductive material comprises aluminum.
7. The heat-trimmable resistor of claim 6 , wherein the electrically-conductive material further comprises copper.
8. The heat-trimmable resistor of claim 1 , wherein an active area heating efficiency of the heat-trimmable resistor is greater than about 350° C./W.
9. The heat-trimmable resistor of claim 1 , wherein the thin-film resistive element is patterned to have one or a plurality of elongated legs and the thin-film heating region is separated from the one or a plurality of elongated legs by at least one thermally-conductive material.
10. The heat-trimmable resistor of claim 9 , wherein the plurality of legs are substantially parallel.
11. The heat-trimmable resistor of claim 9 , wherein the plurality of legs are configured in a serpentine pattern.
12. The heat-trimmable resistor of claim 9 , wherein the one or plurality of legs each have a length between about 10 microns and about 300 microns.
13. The heat-trimmable resistor of claim 9 , wherein the one or plurality of legs each have a width between about 250 nm and about 10 microns.
14. The heat-trimmable resistor of claim 9 , wherein the electrically-conductive material is deposited proximal to at least one end portion of the one or plurality of elongated legs.
15. The heat-trimmable resistor of claim 14 , wherein the deposited electrically-conductive material is deposited to connect to at least one end portion of the thin-film heating region.
16. The heat-trimmable resistor of claim 14 , wherein the electrically-conductive material further electrically connects with an underlying first electrical conductor.
17. The heat-trimmable resistor of claim 16 , wherein the connection with the first electrical conductor is formed through at least one via.
18. The heat-trimmable resistor of claim 16 , wherein the thin-film resistive element electrically connects with a second electrical conductor.
19. The heat-trimmable resistor of claim 18 , wherein the first electrical conductor and second electrical conductor are deposited at the same time.