SPUTTERING OF THERMALLY RESISTIVE MATERIALS INCLUDING METAL CHALCOGENIDES

• US 20080099326A1
• Filed: 07/17/2007
• Published: 05/01/2008
• Est. Priority Date: 10/26/2006
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: YE, MENGQI, Ding, Peijun, Miller, Keith A., Yoshidome, Goichi, Tao, Rong
• Granted Patent: US 8,500,963 B2
• Time in Patent Office: Days
• US Class Current: 204/192.25
• CPC Class Codes: C23C 14/0623 Sulfides, selenides or tellurides
• CPC Class Codes: C23C 14/351 using a magnetic field in close vicinity to the substrate
• CPC Class Codes: C23C 14/541 Heating or cooling of the substrates

Abstract

A plasma sputtering method for metal chalcogenides, such as germanium antimony telluride (GST), useful in forming phase-change memories. The substrate is held at a selected temperature at which the material deposits in either an amorphous or crystalline form. GST has a low-temperature amorphous range and a high-temperature crystalline range separated by a transition band of 105-120° C. Bipolar pulsed sputtering with less than 50% positive pulses of less than 10:s pulse width cleans the target while maintain the sputtering plasma. The temperature of chamber shields is maintained at a temperature favoring crystalline deposition or they may be coated with arc-spray aluminum or with crystallographically aligned copper or aluminum.

Claims

1. A method of sputtering a material comprising a metal chalcogenide capable of forming in a crystalline form and an amorphous form, comprising:

magnetron sputtering a target comprising the metal chalcogenide; and

maintaining a temperature of a substrate disposed in opposition to the target at a selected temperature such that the metal chalcogenide deposits in a selected one of the crystalline form and the amorphous form.

2. The method of claim 1, wherein the metal chalcogenide comprises germanium antimony telluride.

3. The method of claim 1, wherein the selected form is the crystalline form and the selected temperature is above 100°

C.

4. The method of claim 3, wherein the selected temperature is above 120°

C.

5. The method of claim 4, wherein the selected temperature is above 140°

C. and below 350°

C.

6. The method of claim 2, wherein the selected formed is the amorphous form and the selected temperature is less than 110°

C.

7. The method of claim 6, wherein the selected temperature is less than 100°

C.

8. The method of claim 7, wherein the selected temperature is less than 50°

C. and greater than 0°

.

9. The method of claim 1, wherein the substrate temperature is controlled by use of a thermal transfer gas supplied to an area between the substrate and a temperature-controlled substrate support and means for holding the substrate against the substrate support.

10. The method of claim 1, further comprising:

rotating a magnetron to pass over a center of the target

applying DC power of no more than 4 W/cm² to the target; and

at least one of

applying from a sidewall of the chamber supporting the target a magnetic field having components along a central axis of the chamber, or

RF biasing an electrode supporting the substrate through a capacitive coupling circuit.

11. The method of claim 10, including both the applying and the RF biasing steps.

12. The method of claim 1, further comprising:

exciting a plasma in a plasma chamber including the magnetron disposed in back of the target comprising the metal chalcogenide; and

after the plasma has been excited, reducing a pressure in the chamber to no more than 0.8 milliTorr to effect at least partial self-sustained sputtering of the target.

13. The method of claim 1, comprising applying to the target a repetitive pulse form having a repetition frequency of between 10 and 350 kHz and having a positive portion of a duration less than that of a negative portion.

14. The method of claim 13, wherein the positive portion has a pulse width of no greater than 10 microseconds.

15. The method of claim 13, wherein the positive portion has a magnitude less than a magnitude of the negative portion.

16. A method of sputtering a metal chalcogenide target disposed in a plasma sputtering chamber, comprising:

applying to the target a repetitive pulse form having a repetition frequency of between 10 and 350 kHz and having a positive portion of a duration less than that of a negative portion.

17. The method of claim 16, where the magnitude of the positive portion is no more than half a magnitude of the negative portion.

18. The method of claim 16, wherein the positive portion has a duration of no more than 10 microseconds.

20. The method of claim 18, wherein the temperature of the shield is at least 105°

C.

21. The method of claim 18, wherein said maintaining step includes coupling a heat source to the shield.

19. A method of sputtering a target comprising a metal chalcogenide capable of forming either an amorphous or a crystalline phase of a material of the target on a substrate, comprising:

maintaining a temperature of a shield in the sputtering chamber to a temperature at which the crystalline and not the amorphous phase forms on the shield.