Ion Implantation with Heavy Halogenide Compounds

• US 20100022076A1
• Filed: 07/22/2008
• Published: 01/28/2010
• Est. Priority Date: 07/22/2008
• Status: Active Grant

• Current Assignee: Varian Semiconductor Equipment Associates Incorporated (Applied Materials Incorporated)
• Original Assignee: Varian Semiconductor Equipment Associates Incorporated (Applied Materials Incorporated)
• Inventors: Godet, Ludovic, Papasouliotis, George D., Arevalo, Edwin
• Granted Patent: US 7,927,986 B2
• Time in Patent Office: Days
• US Class Current: 438/513
• CPC Class Codes: H01J 2237/31701 Ion implantation
• CPC Class Codes: H01J 37/32412 Plasma immersion ion implantation
• CPC Class Codes: H01L 21/2236 from or into a plasma phase
• CPC Class Codes: H01L 21/26513 of electrically active species
• CPC Class Codes: H01L 21/2658 of a molecular ion, e.g. decaborane

Abstract

A method of plasma doping includes providing a dopant gas comprising a dopant heavy halogenide compound gas to a plasma chamber. A plasma is formed in the plasma chamber with the dopant heavy halogenide compound gas and generates desired dopant ions and heavy fragments of precursor dopant molecule. A substrate in the plasma chamber is biased so that the desired dopant ions impact the substrate with a desired ion energy, thereby implanting the desired dopant ions and the heavy fragments of precursor dopant molecule into the substrate, wherein at least one of the ion energy and composition of the dopant heavy halogenide compound is chosen so that the implant profile in the substrate is substantially determined by the desired dopant ions.

Claims

1. A method of plasma doping comprising:

a. providing a dopant heavy halogenide compound gas to a plasma chamber;

b. forming a plasma in the plasma chamber with the dopant heavy halogenide compound gas, the plasma generating desired dopant ions and heavy fragments of precursor dopant molecule; and

c. biasing a substrate in the plasma chamber so that the desired dopant ions impact the substrate with a desired ion energy, thereby implanting the desired dopant ions and the heavy fragments of precursor dopant molecule into the substrate, wherein at least one of the ion energy and a composition of the dopant heavy halogenide compound is chosen so that an implant profile in the substrate is substantially determined by the desired dopant ions.

2. The method of claim 1 wherein the dopant heavy halogenide compound gas comprises a dopant iodide compound gas.

3. The method of claim 1 wherein the dopant heavy halogenide compound gas comprises BI₃ P-type dopant gas feedstock.

4. The method of claim 1 wherein the dopant heavy halogenide compound gas is selected from the group consisting of PI₃ and AsI₃ N-type dopant gas feedstock.

5. The method of claim 1 wherein the dopant heavy halogenide compound gas comprises a dopant bromide compound gas.

6. The method of claim 1 wherein at least one of the ion energy and the composition of dopant heavy halogenide compound gas is chosen to prevent heavy fragments of precursor dopant molecule from implanting to a projected range that is greater than 20% of the projected range of the desired dopant ions.

7. The method of claim 1 wherein at least one of the ion energy and the composition of dopant heavy halogenide compound gas is chosen so that a projected range of the heavy fragments of precursor dopant molecule is less than a thickness of a surface layer on the substrate.

8. The method of claim 1 wherein at least one of the ion energy and the composition of dopant heavy halogenide compound gas is chosen so that etching caused by physically sputtering and chemical etching during plasma doping is at least partially compensated by the deposition that occurs during plasma doping.

9. The method of claim 1 wherein at least one of the ion energy and the composition of dopant heavy halogenide compound gas is chosen to obtain a predetermined ratio of desired dopant ions to at least one of the heavy fragments of precursor dopant molecule.

10. The method of claim 1 further comprising providing GeI₄ gas to the plasma chamber and forming a plasma in the plasma chamber with the GeI₄ gas, the plasma creating species that cause at least one of pre-amorphization and strain upon implantation into the substrate.

11. The method of claim 1 wherein the plasma further generates dilutent gas ions.

12. The method of claim 11 wherein the composition of the dopant heavy halogenide compound is chosen to reduce a number of dilutent gas ions implanted into the substrate.

13. A method of plasma doping comprising:

a. forming a surface layer on a substrate;

b. providing a dopant heavy halogenide compound gas to a plasma chamber;

c. forming a plasma in the plasma chamber with the dopant heavy halogenide compound gas, the plasma generating desired dopant ions and heavy fragments of precursor dopant molecule; and

d. biasing a substrate in the plasma chamber so that the desired dopant ions impact the substrate with a desired ion energy, thereby implanting the desired dopant ions into the substrate to a desired projected range, wherein at least one of the ion energy and a composition of the dopant heavy halogenide compound is chosen so that the heavy fragments of precursor dopant molecule are implanted to a projected range that is within the surface layer formed on the surface of the substrate.

14. The method of claim 13 wherein the surface layer comprises an oxide layer.

15. The method of claim 13 wherein the dopant heavy halogenide compound gas comprises a dopant iodide compound gas.

16. The method of claim 13 wherein the dopant heavy halogenide compound gas comprises a dopant bromide compound gas.

17. The method of claim 13 wherein a projected range of the heavy fragments of precursor dopant molecule is less than a thickness of the surface layer.

18. The method of claim 13 wherein at least one of the ion energy and the composition of dopant heavy halogenide compound gas is chosen so that etching caused by physically sputtering and chemical etching during plasma doping is at least partially compensated by the deposition that occurs during plasma doping.

19. The method of claim 13 wherein at least one of the ion energy and the composition of dopant heavy halogenide compound gas is chosen to obtain a predetermined ratio of desired dopant ions to at least one of the heavy fragments of precursor dopant molecule.

20. The method of claim 13 wherein the plasma further generates dilutent gas ions.

21. The method of claim 20 wherein the composition of the dopant heavy halogenide compound is chosen to reduce a number of dilutent gas ions implanting into the substrate.

22. A method of ion implanting comprising:

a. generating dopant and dopant heavy halogenide compound ions;

b. accelerating the dopant and dopant heavy halogenide compound ions; and

c. directing the accelerated dopant and dopant heavy halogenide compound ions to a substrate, thereby implanting the accelerated dopant and dopant heavy halogenide compound ions in the substrate with a desired energy, wherein at least one of the ion energy and a composition of the dopant heavy halogenide compound is chosen so that an implant profile in the substrate is substantially determined by the desired dopant ions.

23. The method of claim 22 wherein the dopant heavy halogenide compound gas comprises a dopant iodide compound gas.

24. The method of claim 22 wherein the dopant heavy halogenide compound gas comprises a dopant bromide compound gas.

25. The method of claim 22 wherein at least one of the ion energy and the composition of dopant heavy halogenide compound gas is chosen to obtain a predetermined ratio of desired dopant ions to at least one of the heavy fragments of precursor dopant molecule.

26. The method of claim 22 further comprising selecting desired dopant and dopant heavy halogenide compound ions and accelerating only the selected dopant and dopant heavy halogenide compound ions.