Method to form a contact hole

• US 20050181588A1
• Filed: 02/13/2004
• Published: 08/18/2005
• Est. Priority Date: 02/13/2004
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Chartered Semiconductor Manufacturing Incorporated (Mamoura Diversified Global Holding PJSC)
• Inventors: Kim, Jeong-Ho
• Granted Patent: US 7,291,550 B2
• Time in Patent Office: Days
• US Class Current: 438/586
• CPC Class Codes: H01L 21/02046 Dry cleaning only H01L21/02085 takes precedence
• CPC Class Codes: H01L 21/02063 the processing being the formation of vias or contact holes
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/31138 by dry-etching
• CPC Class Codes: H01L 21/76897 Formation of self-aligned vias or contact plugs, i.e. involving a lithographically uncritical step self-aligned silicidation on field effect transistors H01L29/665

Abstract

A example method of forming of a contact hole by removing residue and oxide spacer beside a nitride spacer after a CF containing etch. We provide a gate structure with nitride spacers on the sidewalls of the gate. We provide a dielectric layer (oxide) over the substrate and gate structure. We form a contact photoresist pattern over the oxide dielectric layer. We etch the oxide dielectric layer using fluorocarbons (CxFy) to form contact openings and residual spacer. The photoresist is striped. Preferably, a NF₃ and N₂ and H₂ plasma treatment is performed to deposit a byproducts layer over the residual spacer. The byproducts layer and residual spacer are removed preferably using one of the following processes: (1) heat (2) DI rinse or (3) IR or UV radiation.

Claims

1. A method of forming a contact hole;

comprising the steps of;

a) providing a gate structure over a substrate;

b) forming a nitride liner over said gate structure and said substrate;

c) providing a dielectric layer over the nitride liner;

d) forming a contact photoresist pattern over the dielectric layer;

e) performing a contact opening etch by etching the dielectric layer to form a contact opening and a residual spacer;

said contact opening exposes said nitride liner on said gate structure sidewalls and on said substrate adjacent to said gate structure;

said residual spacer is on the sidewalls of said nitride liner;

f) striping said contact photoresist pattern;

g) performing a plasma treatment comprising gases containing fluorine (F), nitrogen (N) &

hydrogen (H) to deposit a by-products layer over said residual spacer and said dielectric layer;

h) removing said by-products layer and said residual spacer.

2. The method of claim 1 which further comprises:

removing said by-products layer and said residual spacer using a process selected from the group consisting of;

(1) heating;

(2) DI rinsing;

or (3) IR or UV radiating.

3. The method of claim 1 which further comprises:

said residual spacer comprised of oxide.

4. The method of claim 1 which further comprises:

etching said nitride liner using a nitride etch to expose the surface of said substrate in said contact opening;

forming contacts to said substrate in said contact openings;

forming a first insulation layer over said contacts and said substrate and oxide dielectric layer.

5. The method of claim 1 wherein said gate structure is comprised of a gate dielectric, a gate electrode and a nitride hard mask.

6. The method of claim 1 wherein said dielectric layer is comprised of oxide.

7. The method of claim 1 wherein said dielectric layer is comprised of oxide;

said dielectric layer is formed by a HDP oxide or BPSG oxide process and has a thickness between 3000 and 10,000 Å

.

8. The method of claim 1 wherein the contact opening etch comprises:

a RF bias power between 500 and 1000 W, a process pressure between 5 and 200 mTorr, a carbon fluoride containing gas with a flow between 3 and 50 sccm, a O₂ flow between 0 and 50 sccm, a CH₂F₂ or CH₃F flow between 0 and 50 sccm, a inert gas flow between 0 and 1000 sccm.

9. The method of claim 1 wherein the stripping of said contact photoresist pattern comprises:

a microwave bias power between 100 and 1000 W, a process pressure between 5 and 5000 mTorr., a O2/N2 ratio between 10;

1 and 20;

1.

10. The method of claim 1 wherein the plasma treatment in a down stream plasma tool comprises flowing N₂ and H₂ and using microwave or RF energy to create a nitrogen and hydrogen plasma upstream of the treatment chamber where the substrate is held;

adding NF₃ to the nitrogen and hydrogen plasma and flowing the gases into the treatment chamber to plasma treating the substrate.

11. The method of claim 1 wherein the plasma treatment comprises:

flowing NF₃ between 5 and 1000 sccm, flowing N₂ between 5 and 5000 sccm, flowing H₂ between 5 and 2000 sccm, at a microwave power between 50 and 5000 W;

the nitrogen and hydrogen feeds flow through a plasma applicator before entering a chamber.

12. The method of claim 1 wherein the plasma treatment comprises:

flowing gas with a molar composition of NF₃% between 1 and 75%, N₂ between 1 and 99% sccm, flowing H₂ between 1 and 75%;

the nitrogen and hydrogen feeds flow through a plasma applicator before entering a chamber.

13. The method of claim 1 wherein the plasma treatment comprises:

flowing gas with a molar composition of NF₃% between 1 and 30%, N₂ between 70 and 95% sccm, flowing H₂ between 1 and 30%;

the nitrogen and hydrogen feeds flow through a plasma applicator before entering a chamber.

14. The method of claim 1 wherein the heating of the substrate to remove said by-products layer and said residual spacer comprises heating the substrate to a temperature greater than 50°

C. in a N₂ gas or air ambient.

15. The method of claim 1 wherein the by-products layer is comprised of N_xH_yF_z with x between 1 and 10;

Y between 1 and 7; and

z between 1 and 7.

16. A method of fabrication a contact hole and removing a residue spacer beside a nitride liner after contact opening etch;

comprising the steps of;

a) providing a gate structure over a substrate;

b) providing spacers over the sidewalls of the gate structure;

c) forming a nitride liner over said spacers and said gate structure and said substrate;

d) providing a dielectric layer over the nitride liner;

said dielectric layer is comprised of oxide;

e) forming a contact photoresist pattern over the oxide dielectric layer;

f) etching the dielectric layer using fluorocarbons to form a contact opening, a residual spacer and a polymer layer;

said contact opening exposes said nitride liner on said gate structure sidewalls and on said substrate adjacent to said gate structure;

said residual spacer is on the sidewalls of said nitride liner;

said polymer layer over said residual spacer and said nitride liner;

said residual spacer is comprise of oxide;

(1) the etch process of said contact opening comprises;

carbon fluoride O₂, and CH₂F₂ etchants;

g) striping said contact photoresist pattern and said polymer layer;

h) performing a NF₃ and nitrogen and hydrogen plasma treatment to deposit a by-products layer over said residual spacer and said dielectric layer;

i) removing said by-products layer and said residual spacer using one of the following processes;

(1) heat;

(2) DI rinse;

or (3) IR or UV radiation.

17. The method of claim 16 which further includes:

etching said nitride liner using a nitride etch to expose the surface of said substrate in said contact opening;

forming contacts to said substrate in said contact openings;

forming a first insulation layer over said contacts and said substrate and dielectric layer.

18. The method of claim 16 wherein said dielectric layer is formed by a HDP oxide or BPSG oxide process and has a thickness between 3000 and 10,000 Å

.

19. The method of claim 16 wherein said residual spacer comprised of over 90% oxide.

20. The method of claim 16 wherein the etch process of said contact opening comprises:

a RF bias power between 500 and 1000 W, a process pressure between 5 and 200 mTorr, a carbon fluoride containing gas with a flow between 3 and 50 sccm, a O₂ flow between 0 and 50 sccm, a CH₂F₂ (or CH₃F) flow between 0 and 50 sccm, a inert gas (such as Ar or He) flow between 0 and 1000 sccm;

21. The method of claim 16 wherein the stripping process comprises:

a microwave bias power between 100 and 1000 W, a process pressure between 5 and 5000 mTorr., a O₂₁N2 ratio between 10;

1 and 20;

1.

22. The method of claim 16 wherein said plasma treatment tool selected from the group consisting of a Microwave tool, ICP tool, a MERIE tool, a RIE tool.

23. The method of claim 16 wherein the plasma treatment comprising flowing NF₃ between 5 and 1000 sccm, flowing N₂ between 5 and 5000 sccm, flowing H₂ between 5 and 2000 sccm, at a microwave power between 50 and 5000 W;

the nitrogen and hydrogen feeds flow through a plasma applicator before entering a chamber;

the NF₃ flow does not pass thru a plasma applicator.

24. The method of claim 16 wherein the NF₃ and nitrogen and hydrogen plasma treatment comprises:

flowing gas with a composition of NF₃ between 1 and 75%, N₂ between 1 and 99% sccm, flowing H₂ between 1 and 75%;

the nitrogen and hydrogen feeds flow through a plasma applicator before entering a chamber;

the NF₃ flow does not pass thru a plasma applicator.

25. The method of claim 16 wherein the plasma treatment comprises:

flowing gas with a molar composition of NF₃% between 1 and 30%, nitrogen between 70 and 95% sccm, flowing H₂ between 1 and 30%;

the nitrogen and hydrogen feeds flow through a plasma applicator before entering a chamber;

the NF₃ flow does not pass thru a plasma applicator.

26. The method of claim 16 wherein the by-products layer is comprised of N_xH_yF_z with x between 1 and 10;

Y between 1 and 7; and

z between 1 and 7.