CONFORMAL DOPING APPARATUS AND METHOD

• US 20070087574A1
• Filed: 10/13/2005
• Published: 04/19/2007
• Est. Priority Date: 10/13/2005
• Status: Active Grant

• Current Assignee: Varian Semiconductor Equipment Associates Incorporated (Applied Materials Incorporated)
• Original Assignee: Varian Semiconductor Equipment Associates Incorporated (Applied Materials Incorporated)
• Inventors: Singh, Vikram, Gupta, Atul, Miller, Timothy, Winder, Edmund
• Granted Patent: US 7,524,743 B2
• Time in Patent Office: Days
• US Class Current: 438/758
• CPC Class Codes: H01J 37/32412 Plasma immersion ion implantation
• CPC Class Codes: H01J 37/32623 Mechanical discharge control means
• CPC Class Codes: H01J 37/32697 Electrostatic control
• CPC Class Codes: H01L 21/2236 from or into a plasma phase
• CPC Class Codes: H01L 21/26506 in group IV semiconductors
• CPC Class Codes: H01L 21/26526 Recoil-implantation
• CPC Class Codes: H01L 21/2658 of a molecular ion, e.g. decaborane
• CPC Class Codes: H01L 21/26586 characterised by the angle between the ion beam and the crystal planes or the main crystal surface
• CPC Class Codes: H01L 29/66803 with a step of doping the vertical sidewall, e.g. using tilted or multi-angled implants

Abstract

A method of doping includes depositing a layer of dopant material on nonplanar and planar features of a substrate. Inert ions are generated from an inert feed gas. The inert ions are extracted towards the substrate where they physically knock the dopant material into both the planar and nonplanar features of the substrate.

Claims

1. A method of doping comprising:

depositing a layer of dopant material on nonplanar and planar features of a substrate;

generating inert ions from an inert feed gas; and

extracting the inert ions towards the substrate, the inert ions physically knocking the dopant material into both the planar and nonplanar features of the substrate.

2. The method of claim 1 wherein the inert feed gas comprises at least one of He, Ne, Ar, Kr and Xe.

3. The method of claim 1 wherein the layer of dopant material is deposited using at least one of B2H6, PH3, AsH3, BF3, PF3 and AsF5.

4. The method of claim 1 wherein a mass of the inert ions is chosen to be similar to a mass of the dopant ions.

5. The method of claim 1 wherein the extracting the inert ions comprises applying a bias voltage to at least one of a platen supporting the substrate and a grating positioned proximate to the platen.

6. The method of claim 1 wherein the inert ions are extracted towards the substrate at a non-normal angle relative to the planar surface of the substrate.

7. The method of claim 1 wherein the extracting the inert ions towards the substrate is performed with a beam-line ion implanter.

8. The method of claim 1 wherein the depositing the layer of dopant material on nonplanar features of the substrate and the extracting the inert ions towards the substrate are performed in different chambers.

9. The method of claim 1 further comprising biasing the substrate with at least one of a DC, pulsed DC, and an AC bias while extracting the inert ions towards the substrate.

10. The method of claim 1 wherein at least one of an amplitude, a repetition rate, and a pulse width is chosen to achieve a desired doping profile of the planar and nonplanar features of the substrate after annealing.

11. The method of claim 1 wherein a thickness of the deposited layer on the planar features is in a range that is between 1-100 times the thickness of the deposited layer on the nonplanar features.

12. The method of claim 1 wherein at least one of a thickness of the layer of dopant material, a density of inert ions generated, a pressure proximate to the substrate, and a voltage applied to at least one of the platen supporting the substrate and a grating is chosen so that the doping profile of the nonplanar features approximately matches a doping profile of planar surfaces.

13. A method of doping, the method comprising:

generating a first group of dopant ions from a first volume of feed gas;

applying a voltage to at least one of a platen supporting a substrate having planar and nonplanar features and a grating in order to extract the first group of dopant ions through the grating towards the substrate;

generating a plasma proximate to the substrate from a second volume of feed gas, the plasma depositing dopant material on the nonplanar features of the substrate;

generating an oxidizer plasma comprising reactive neutrals that conformally react with the dopant materials deposited on the nonplanar features of the substrate to render the dopant material deposited on nonplanar features of the substrate at least partially inert and to protect the nonplanar features during photoresist stripping processing;

stripping photoresist layers on the substrate; and

annealing the substrate to diffuse dopant material on the planar and the nonplanar features of the substrate.

14. The method of claim 13 wherein the oxidizer plasma is generated with at least one of oxygen and nitrogen gas.

15. The method of claim 13 wherein the annealing generates a thermal gradient from a top of the nonplanar features to the bottom of the nonplanar features.

16. The method of claim 13 wherein the annealing comprises rapid thermal annealing.

17. The method of claim 13 wherein the annealing comprises a multi-step anneal.

18. The method of claim 13 wherein a rate of depositing dopant ions on nonplanar features of the substrate is controlled relative to a rate of implanting dopant ions in the planar surfaces of the substrate so that a doping profile of the nonplanar features after annealing approximately matches a doping profile of the planar surfaces after annealing.

19. The method of claim 13 wherein the annealing activates the dopant ions implanted into the substrate.

20. A doping apparatus comprising:

a means for depositing a layer of dopant material on nonplanar and planar features of a substrate;

a means for generating inert ions from an inert feed gas; and

a means for extracting the inert ions towards the substrate, the inert ions physically knocking the dopant material into both the planar and nonplanar features of the substrate.

21. A doping apparatus comprising:

a means for generating a first group of dopant ions from a first volume of feed gas;

a means for applying a voltage to at least one of a platen supporting a substrate having planar and nonplanar features and a grating in order to extract the first group of dopant ions through the grating towards the substrate;

a means for generating a plasma proximate to the substrate from a second volume of feed gas, the plasma depositing dopant material on the nonplanar features of the substrate;

a means for generating an oxidizer plasma comprising reactive neutrals that conformally react with the dopant materials deposited on the nonplanar features of the substrate to render the dopant material deposited on nonplanar features of the substrate at least partially inert and to protect the nonplanar features during photoresist stripping processing;

a means for stripping photoresist layers on the substrate; and

a means for annealing the substrate to diffuse dopant material on the planar and the nonplanar features of the substrate.