Methods of forming a thin film resistor

Patent metadata

Field	Value
Publication number	US-9963777-B2
Application number	US-201213646940-A
Country	US
Kind code	B2
Filing date	Oct 8, 2012
Priority date	Oct 8, 2012
Publication date	May 8, 2018
Grant date	May 8, 2018

Abstract

Methods of forming a thin film are disclosed. One such method can include sputtering a target material to form a first thin film resistor and adjusting a parameter of deposition to modulate a property of a subsequently formed second thin film resistor. For instance, a substrate bias and/or a substrate temperature can be adjusted to modulate a property of the second thin film resistor. A temperature coefficient of resistance (TCR) and/or another property of the second thin film resistor can be modulated by adjusting the parameter of deposition. The target material sputtered onto the substrate can include, for example, a Cr alloy, a Ni alloy, SiCr, NiCr, or the like. A relationship can be established between the substrate bias and/or substrate temperature and the thin film resistor property, and the relationship can be used in selecting deposition conditions for a desired property value.

First claim

What is claimed is:

1. A method of forming thin film resistors, the method comprising:
sputtering a single target material to form a first thin film resistor while applying a radio frequency (RF) substrate bias having a first RF bias level such that no other target material is sputtered to form the thin film resistor, said sputtering being non-reactive RF sputtering;
adjusting the RF substrate bias to have a second RF bias level after sputtering the single target material to form the first thin film resistor, the second RF bias level being different from the first RF bias level; and
after adjusting the RF substrate bias, forming a second thin film resistor by non-reactively sputtering substantially the same single target material while applying the RF substrate bias having the second RF bias level to modulate a temperature coefficient of resistance (TCR) of the second thin film resistor relative to a TCR of the first thin film resistor, wherein the second thin film resistor has a non-zero TCR and a resistance of at least 2 kilo-ohms.

2. The method of claim 1 , wherein the single target material comprises at least one of a Cr alloy or a Ni alloy.

3. The method of claim 1 , further comprising varying a substrate temperature prior to said forming the second thin film resistor to further modulate the TCR of the second thin film resistor.

4. The method of claim 1 , further comprising adjusting a substrate temperature after the first thin film resistor is formed and prior to forming the second thin film resistor, the adjusted substrate temperature being above 500° C.

5. The method of claim 1 , wherein the TCR of the first thin film resistor and the TCR of the second thin film resistor are each in a range from +25 ppm/° C. to +500 ppm/° C.

6. The method of claim 1 , wherein the first thin film resistor and the second thin film resistor are formed on different substrates.

7. The method of claim 1 , wherein the first thin film resistor and the second thin film resistor have substantially the same resistance, and wherein the resistance is between 20 kilo-ohms and 1 mega-ohm.

8. The method of claim 1 , wherein the first thin film resistor and the second thin film resistor formed by RF sputtering have thicknesses in the range from about 20 Å to 5,000 Å.

9. A method of forming thin film resistors, the method comprising:
radio frequency (RF) sputtering a material on a first substrate to form a first thin film resistor on the first substrate, the first thin film resistor having a first resistance of at least 2 kilo-ohms;
applying an RF substrate bias across the first substrate at a first RF bias level during the RF sputtering, the RF sputtering being non-reactive sputtering;
adjusting the RF substrate bias to modulate a property of a second thin film resistor relative to the same property of the first thin film resistor, the adjusted RF bias having a second RF bias level that is different than the first RF bias level; and
forming the second thin film resistor with a non-zero temperature coefficient of resistance (TCR) on a second substrate, the second thin film resistor being formed by non-reactive RF sputtering, wherein the adjusted RF substrate bias is applied to the second substrate, and wherein the second thin film resistor has a second resistance of at least 2 kilo-ohms.

10. The method of claim 9 , wherein the material comprises at least one of a Cr alloy or a Ni alloy.

11. The method of claim 9 , wherein the property of the second thin film resistor is the non-zero TCR, and wherein the non-zero TCR is in a range from +25 ppm/° C. to +500 ppm/° C.

12. The method of claim 11 , wherein adjusting modulates the non-zero TCR of the second thin film resistor, and wherein the first thin film resistor has substantially the same resistance as the second thin film resistor, and wherein the second resistance of the second thin film resistor is between 20 kilo-ohms and 1 mega-ohm.

13. The method of claim 9 , wherein the second substrate is heat to at least 500° C. while the second thin film resistor is formed.

14. The method of claim 9 , wherein adjusting comprises varying at least one of a voltage or a power of the adjusted RF substrate bias applied to the second substrate compared to the respective voltage or power of the RF substrate bias applied to the first substrate.

15. The method of claim 9 , further comprising varying a temperature of the second substrate relative to a temperature of the first substrate to further modulate the property of the second thin film resistor.

16. The method of claim 9 , wherein forming the second thin film resistor comprises RF sputtering substantially the same material on the second substrate.

17. A method of forming a thin film resistor on a substrate, the method comprising:
heating the substrate to a temperature selected in the range from about 500° C. to 1000° C.; and
sputtering a material on a substrate at the temperature to form the thin film resistor on the substrate, the material comprising at least one of SiCr or NiCr; and
wherein the thin film resistor formed by sputtering has a non-zero temperature coefficient of resistance (TCR).

18. The method of claim 17 , wherein the temperature is at least about 600° C.

19. The method of claim 17 , wherein the thin film resistor has a resistance in a range from one milli-ohm to one mega-ohm.

20. The method of claim 1 , wherein the single target material comprises a ceramic component and a metallic component.

21. The method of claim 17 , wherein the sputtering comprises non-reactive RF sputtering.

22. A method of forming a thin film resistor, the method comprising:
selecting a value for a property of a thin film resistor, wherein the property is a temperature coefficient of resistance (TCR) in a range from +25 ppm/° C. to +500 ppm/° C.;
obtaining a value for a deposition parameter associated with the selected property value from a non-reactive sputtering relationship between the deposition parameter and the property, wherein the deposition parameter comprises a radio frequency (RF) substrate bias voltage determined based at least in part on a proportional relationship with the TCR and also on an offset amount;
setting the deposition parameter to the obtained value for the deposition parameter; and
while the deposition parameter is at the obtained value, causing a target material to be non-reactively RF sputtered onto a substrate to form a thin film resistor having the selected value for the property; and
wherein the target material is from only one target.

23. The method of claim 22 , wherein the target material comprises at least one of a Cr alloy or a Ni alloy.

24. The method of claim 17 , wherein sputtering the material comprises radio frequency (RF) sputtering the material and applying an RF bias to the substrate.

25. The method of claim 22 , wherein the thin film resistor has a resistance of at least 2 kilo-ohms.

26. The method of claim 1 , wherein applying the RF substrate bias having the first RF bias level comprises applying the RF substrate bias to an anode positioned across a substrate on which the first thin film resistor is formed.

27. The method of claim 17 , wherein the material that is sputtered onto the substrate is from only one target.

Assignees

• Analog Devices Inc

Inventors

• Morrissey Michael Noel
• Stenson Bernard Patrick

Classifications

• H01C17/232

  Adjusting the temperature coefficient; Adjusting value of resistance by adjusting temperature coefficient of resistance · CPC title

• H01C17/12

  by sputtering · CPC title

• C23C14/34 Primary

  Sputtering · CPC title

• H01L28/24

  Electricity · mapped topic

• C23C14/16

  on metallic substrates or on substrates of boron or silicon · CPC title