Using implants to lower anneal temperatures

• US 5,885,896 A
• Filed: 07/08/1996
• Issued: 03/23/1999
• Est. Priority Date: 07/08/1996
• Status: Expired due to Term

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Nuttall, Michael, Thakur, Randhir P. S.
• Primary Examiner(s): Niebling, John F.
• Assistant Examiner(s): NGUYEN, HA T
• Application Number:
  US08/676,587
• Time in Patent Office: 988 Days
• Field of Search: 438/627, 438/630, 438/645, 438/649, 438/525, 438/532, 438/533, 438/655, 438/653, 438/656, 438/659, 438/664, 438/158, 438/360
• US Class Current: 438/649
• CPC Class Codes: H01L 21/28518 the conductive layers comprising silicides H01L21/28537 takes precedence

Abstract

A method for lowering the anneal temperature required to form a multi-component material, such as refractory metal silicide. A shallow layer of titanium is implanted in the bottom of the contact area after the contact area is defined. Titanium is then deposited over the contact area and annealed, forming titanium silicide. A second embodiment comprises depositing titanium over a defined contact area. Silicon is then implanted in the deposited titanium layer and annealed, forming titanium silicide. A third embodiment comprises combining the methods of the first and second embodiments. In further embodiment, nitrogen, cobalt, cesium, hydrogen, fluorine, and denterium are also implanted at selected times.

Claims

1. A method for forming refractory metal silicide at a metal/semiconductor interface, comprising:

a) implanting a refractory metal in a silicon substrate, to form an implanted region, wherein the refractory metal is selected from the group consisting of titanium, tungsten, tantalum, cobalt and molybdenum;

b) forming a layer of the refractory metal on the implanted region;

c) annealing to form refractory metal silicide, comprising at least silicon and the refractory metal; and

d) implanting an element selected from the group consisting of cobalt, cesium, hydrogen, fluorine, and deuterium at a time selected from the group consisting of the times of prior to implanting the refractory metal and subsequent to annealing.

2. A method for forming refractory metal silicide at a metal/semiconductor interface, comprising:

a) implanting a refractory metal in a silicon substrate, to form an implanted region, wherein the refractory metal is selected from the group consisting of titanium, tungsten, tantalum, cobalt and molybdenum;

b) forming a layer of the refractory metal on the implanted region;

c) annealing to form refractory metal silicide, comprising at least silicon and the refractory metal; and

d) implanting nitrogen into the implanted region at a time selected from the group consisting of prior to annealing and subsequent to annealing, such that the depth of the implanted nitrogen is approximately between 20 to 300 angstroms.

3. A method for forming a plurality of compounds on a semiconductor substrate, comprising the steps of:

a) implanting a first element in a semiconductor substrate, comprising a second element, to form a first implanted region;

b) depositing a layer of material, comprising the first element, on the first implanted region;

c) implanting a third element in the layer of material, to form a second implanted region; and

d) annealing to form at least one compound, comprising at least the first and second elements.

4. The method of claim 3, wherein the first element comprises a refractory metal, selected from the group consisting of titanium, tungsten, tantalum, cobalt, and molybdenum.

5. The method of claim 3, wherein the third element is selected from the group consisting of nitrogen and silicon.

6. The method of claim 3, wherein the annealing step comprises annealing in a nitrogen-containing ambient.

7. The method of claim 3, wherein the annealing step comprises annealing at a temperature of between approximately 500 to 950 degrees Celsius.

8. The method of claim 3, and further comprising the step of implanting an element selected from the group consisting of cobalt, cesium, hydrogen, fluorine, and deuterium at a time selected from the group consisting of the times of:

prior to implanting the first element, prior to implanting the third element, and subsequent to the anneal step.

9. The method of claim 3, wherein the third element comprises nitrogen, and further forming a compound comprising at least the first element and nitrogen during the anneal step.

10. A method for forming titanium silicide on a silicon substrate, comprising the steps of:

a) implanting titanium in a silicon substrate, to form an implanted region;

b) forming a layer of titanium on the implanted region; and

c) annealing to form titanium silicide.

11. The method of claim 10, wherein the silicon substrate comprises the bottom of a contact hole.

12. The method of claim 11, wherein the sides of the contact hole are defined by an insulator material selected from the group consisting of borophosphosilicate glass and doped oxides.

13. The method of claim 10, further comprising the step of implanting nitrogen into the titanium layer at a time selected from the group consisting of the following times:

prior to the annealing step and subsequent to the annealing step, such that the depth of the implanted nitrogen is approximately between 20 to 300 angstroms.

14. The method of claim 13, wherein the silicon substrate comprises the bottom of a contact hole and the sides of the contact hole are defined by an insulator material, selected from the group consisting of borophosphosilicate glass and doped oxides, and the nitrogen is implanted at an angle of between approximately 0 and 50 degrees from a plane perpendicular to the silicon substrate surface, so that nitrogen is implanted into a titanium layer overlying the sides of the contact hole.

15. The method of claim 14, wherein the nitrogen is implanted at an angle of approximately 27 degrees from a plane perpendicular to the silicon substrate surface.

16. A method for forming a plurality of compounds on a semiconductor substrate, comprising:

a) implanting a first element in a semiconductor substrate, comprising a second element, to form a first implanted region, wherein the first element comprises a refractory metal selected from the group consisting of titanium, tungsten, tantalum, cobalt, and molybdenum;

b) depositing a layer of material, comprising the first element, on the first implanted region;

c) implanting a third element in the layer of material, to form a second implanted region, wherein the third element is selected from the group consisting of nitrogen and silicon; and

d) annealing to form at least one compound, comprising at least the first and second elements.

17. The method of claim 16, wherein annealing to form at least one compound comprises annealing in a nitrogen-containing ambient.

18. The method of claim 16, wherein annealing to form at least one compound comprises annealing at a temperature of between approximately 500 to 950 degrees Celsius.

19. The method of claim 16, further comprising implanting an element selected from the group consisting of cobalt, cesium, hydrogen, fluorine, and deuterium at a time selected from the group consisting of the times of prior to implanting the first element, prior to implanting the third element, and subsequent to annealing.

20. The method of claim 16, wherein annealing to form at least one compound further comprises forming a compound comprising at least the first and third elements, wherein the third element comprises nitrogen.

21. A method for forming a plurality of compounds on a semiconductor substrate, comprising:

a) implanting a first element in a semiconductor substrate, comprising a second element, to form a first implanted region, wherein the first element comprises a refractory metal selected from the group consisting of titanium, tungsten, tantalum, cobalt, and molybdenum;

b) depositing a layer of material, comprising the first element, on the first implanted region;

c) implanting a third element in the layer of material, to form a second implanted region, wherein the third element is nitrogen; and

d) annealing in a nitrogen-containing ambient to form at least two compounds, wherein a first compound comprises at least the first and second elements, further wherein a second compound comprises at least the first and third elements.

22. A method for forming a plurality of compounds on a semiconductor substrate, comprising:

a) implanting a first element in a semiconductor substrate, comprising a second element, to form a first implanted region, wherein the first element comprises a refractory metal selected from the group consisting of titanium, tungsten, tantalum, cobalt, and molybdenum;

b) depositing a layer of material, comprising the first element, on the first implanted region;

c) implanting a third element in the layer of material, to form a second implanted region, wherein the third element is selected from the group consisting of nitrogen and silicon;

d) annealing to form at least one compound, comprising at least the first and second elements; and

e) implanting a fourth element selected from the group consisting of cobalt, cesium, hydrogen, fluorine, and deuterium at a time selected from the group consisting of the times of prior to implanting the first element, prior to implanting the third element, and subsequent to annealing.

23. A method for forming titanium silicide on a silicon substrate, comprising:

a) implanting titanium in a silicon substrate, to form an implanted region, wherein the silicon substrate comprises the bottom of a contact hole, further wherein the contact hole has sides defined by an insulator material selected from the group consisting of borophosphosilicate glass and doped oxides;

b) forming a layer of titanium on the implanted region; and

c) annealing to form titanium silicide.

24. A method for forming titanium silicide on a silicon substrate, comprising:

a) implanting titanium in a silicon substrate, to form an implanted region, wherein the silicon substrate comprises the bottom of a contact hole, further wherein the contact hole has sides defined by an insulator material selected from the group consisting of borophosphosilicate glass and doped oxides;

b) forming a layer of titanium on the implanted region;

c) annealing to form titanium silicide; and

d) implanting nitrogen into the layer of titanium at a time selected from the group consisting of the times of prior to annealing and subsequent to annealing.

25. The method of claim 24, wherein implanting nitrogen into the layer of titanium comprises implanting nitrogen at an angle of between approximately 0 and 50 degrees from a plane perpendicular to the silicon substrate surface.

26. The method of claim 25, wherein implanting nitrogen into the layer of titanium comprises implanting nitrogen at an angle of approximately 27 degrees from a plane perpendicular to the silicon substrate surface.