Method of fabricating load resistor

• US 6,140,198 A
• Filed: 11/06/1998
• Issued: 10/31/2000
• Est. Priority Date: 11/06/1998
• Status: Expired due to Fees

• Current Assignee: United Microelectronics Corporation
• Original Assignee: United Microelectronics Corporation
• Inventors: Liou, Fu-Tai
• Primary Examiner(s): Whitehead, Jr., Carl
• Assistant Examiner(s): BROPHY, JAMIE LYNN
• Application Number:
  US09/187,620
• Time in Patent Office: 725 Days
• Field of Search: 438/238, 438/382, 438/385, 438/330, 438/658, 438/659, 438/513, 438/522, 438/527, 438/530
• US Class Current: 438/382
• CPC Class Codes: H01L 28/24 with an active material comprising a refractory, transition or noble metal, metal compound or metal alloy, e.g. silicides, oxides, nitrides
• CPC Class Codes: H10B 10/00 Static random access memory [SRAM] devices
• CPC Class Codes: H10B 10/15 comprising a resistor load element

Abstract

A method of fabricating a load resistor. The load resistor is often applied in a static random access memory. The interconnect between different conductive regions such as gate and source/drain region is formed by applying a hydrogen treatment to a refractory metal oxide layer, while the load resistors are formed by applying a hydrogen treatment with different parameters as the former one. The insulation is formed by the refractory metal oxide layer which is not to be covered.

Claims

1. A method of forming a load resistor, comprising:

providing a substrate having at least a conductive region;

forming an insulation layer on the substrate with an opening exposing the conductive region;

forming a refractory metal oxide layer on the insulation layer and to fill the opening;

performing a two-step hydrogen treatment to convert a first part of the refractory metal oxide layer into a conductor with a first resistance, and to convert a second part of the refractory metal oxide layer into a conductor with a second resistance, wherein the two-step hydrogen treatment includes a first step for converting the first part and a second step for converting the second part.

2. The method according to claim 1, wherein the conductive region includes a source/drain region of a metal-oxide semiconductor device.

3. The method according to claim 1, wherein the conductive region includes a gate of a metal-oxide semiconductor device.

4. The method according to claim 1, wherein the refractory metal oxide layer is formed from a material selected from at least one of TiO₂, Ta₂ O₅, Fe₂ O₃, and BaTiO₃.

5. The method according to claim 1, wherein the two-step hydrogen treatment further comprises:

forming a first mask layer with at least an opening to expose the first part of the refractory metal oxide layer;

performing the first step of the two-step hydrogen treatment using the first mask to convert the exposed first part of the refractory metal oxide layer into the conductor with the first resistance;

removing the first mask layer;

forming a second mask layer to expose the second part of the refractory metal oxide layer; and

performing the second step of the two-step hydrogen treatment to convert the exposed second part of the refractory metal oxide into the conductor with the second resistance, while a third part of the refractory metal oxide may remain as an insulator without being converted.

6. The method according to claim 5, wherein the first step of the hydrogen treatment is performed with a longer duration than the second step of the hydrogen treatment.

7. The method according to claim 1, wherein the hydrogen treatment includes a hydrogen thermal treatment.

8. The method according to claim 1, wherein the hydrogen treatment includes a hydrogen plasma treatment.

9. A method of forming a load resistor, comprising:

providing a substrate having at least a conductive region;

forming an insulation layer with an opening exposing the conductive region;

forming a refractory metal oxide layer on the insulation layer to fill the opening;

removing a part of the refractory metal oxide layer;

converting a first remaining part of the refractory metal oxide layer into a conductor with a high resistance; and

converting a second remaining part of the refractory metal oxide into a conductor with a low resistance.

10. The method according to claim 9, wherein the conductive region includes a source/drain region of a metal-oxide semiconductor device.

11. The method according to claim 9, wherein the conductive region includes a gate of a metal-oxide semiconductor device.

12. The method according to claim 9, wherein the refractory metal oxide layer is formed from a material selected from at least one of TiO₂, Ta₂ O₅, Fe₂ O₃, and BaTiO₃.

13. The method according to claim 9, wherein the steps of converting the first and the second remaining parts of the refractory metal oxide layer each include a step of hydrogen treatment.

14. The method according to claim 13, wherein the hydrogen treatment includes a hydrogen thermal treatment.

15. The method according to claim 13, wherein the hydrogen treatment includes a hydrogen plasma treatment.

16. A method of forming a load resistor, comprising:

providing a substrate having at least a conductive region;

forming an insulation layer with an opening exposing the conductive region;

forming a refractory metal oxide layer on the insulation layer to fill the opening;

removing a part of the refractory metal oxide layer;

performing a first hydrogen treatment to the remaining refractory metal oxide layer; and

performing a second hydrogen treatment to a part of the refractory metal oxide layer.

17. The method according to claim 16, wherein the conductive region includes a gate of a metal-oxide semiconductor device.

18. The method according to claim 16, wherein the refractory metal oxide layer is formed from a material selected from at least one of a group consisting of TiO₂, Ta₂ O₅, Fe₂ O₃, and BaTiO₃.

19. The method according to claim 16, wherein each of the first and the second hydrogen treatments includes a hydrogen plasma treatment.

20. The method according to claim 16, wherein each of the first and the second hydrogen treatments includes a hydrogen thermal treatment.

21. A method of forming a load resistor of a static random access memory, comprising:

providing a substrate having at least a metal-oxide semiconductor device which comprises a source/drain region and a gate;

forming an insulation layer with openings exposing the gate and the source/drain region;

forming a refractory metal oxide layer on the insulation layer and to fill the openings;

performing a first step of a hydrogen treatment with a first mask to convert a first part of the refractory metal oxide layer into a first conductor with a first conductivity; and

performing a second step of the hydrogen treatment with a second mask to convert a second part of a refractory metal oxide layer into a second conductor with a second conductivity, while a third part of the refractory metal oxide layer may remain as an insulator without being converted.

22. The method according to claim 21, wherein a relative difference between the first conductivity and the second conductivity is adjusted by controlling an oxygen content in the refractory metal oxide layer through the first step and the second step of hydrogen treatment.