Etching method, plasma processing system and storage medium

• US 20070284337A1
• Filed: 03/29/2007
• Published: 12/13/2007
• Est. Priority Date: 03/31/2006
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Yashiro, Jun, Mochizuki, Ryou
• Granted Patent: US 8,177,990 B2
• Time in Patent Office: Days
• US Class Current: 216/67
• CPC Class Codes: H01J 2237/334 Etching
• CPC Class Codes: H01J 37/3244 Gas supply means
• CPC Class Codes: H01L 21/0337 characterised by the process involved to create the mask, e.g. lift-off masks, sidewalls, or to modify the mask, e.g. pre-treatment, post-treatment
• CPC Class Codes: H01L 21/0338 Process specially adapted to improve the resolution of the mask
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/31122 of layers not containing Si, e.g. PZT, Al2O3
• CPC Class Codes: H01L 21/31138 by dry-etching
• CPC Class Codes: H01L 21/31144 using masks
• CPC Class Codes: H01L 21/76816 Aspects relating to the layout of the pattern or to the size of vias or trenches layout of the interconnections per se H01L23/528; CAD of ICs G06F30/00
• CPC Class Codes: Y10S 438/947 Subphotolithographic processing

Abstract

Disclosed is a method of etching a substrate having a layered structure in which a photoresist mask with a pattern, a coating film made of silicon oxide, and an organic film are laminated in that order from the top. Before etching the coating film of silicon oxide, a deposit is deposited on the photoresist mask by using plasma generated from a hydrocarbon gas such as CH₄ gas so as to narrow the size of openings in the pattern of the photoresist mask. The pattern of the photoresist mask is well transferred to the organic film through the coating film, and a pattern with openings having a high aspect ratio can be formed in the organic film and toppling of the pattern in the organic film can be prevented. The organic film with the transferred pattern is used as an etch mask for etching the underlying layer.

Claims

1. A method of etching a substrate having a layered structure in which a mask made of an organic material and having a pattern formed therein, a coating film made of silicon oxide, and an organic film are laminated in that order from top, said method comprising the steps of:

converting, into plasma, a process gas containing a hydrocarbon gas in a processing chamber, and producing a deposit covering the pattern of the mask by using the plasma; and

thereafter etching the coating film in the processing chamber by using a plasma, by using the mask covered by the deposit as an etch mask.

2. The etching method according to claim 1, further comprising a step of etching the organic film by using the coating film as an etch mask, after etching the coating film.

3. The etching method according to claim 1, wherein the process gas contains the hydrocarbon gas, and a diluent gas not containing halogen.

4. The etching method according to claim 2, wherein the process gas contains the hydrocarbon gas, and a diluent gas not containing halogen.

5. The etching method according to claim 1, wherein the hydrocarbon gas is CH₄ gas.

6. The etching method according to claim 3, wherein the hydrocarbon gas is CH₄ gas.

7. The etching method according to claim 4, wherein the hydrocarbon gas is CH₄ gas.

12. A storage medium storing a computer program that is used for a plasma processing system and that operates on a computer, wherein the computer program includes steps for performing the etching method according to claim 1.

8. A plasma processing system that performs an etching process to a substrate having a layered structure in which a mask made of an organic material and having a pattern formed therein, a coating film made of silicon oxide, and an organic film are laminated in that order from top, said plasma processing system comprising:

a processing chamber having therein a table for placing the substrate thereon;

means for supplying a process gas containing a hydrocarbon gas into the processing chamber;

means for supplying a gas for etching the coating film into the processing chamber;

means for evacuating an interior of the processing chamber;

means for converting a gas in the processing chamber into plasma; and

a control unit for, after the substrate is placed on the table, controlling each of the means such that the process gas containing the hydrocarbon gas is converted into plasma to produce a deposit covering the pattern of the mask by using the plasma thus converted, and thereafter the gas for etching the coating film is converted into plasma.

9. The plasma processing system according to claim 8, further comprising means for supplying a gas used for etching the organic film into the processing chamber, wherein the control unit is also configured so that, after the coating film is etched, the control unit controls each of the means such that a gas for etching the organic film is converted into plasma.

10. The plasma processing system according to claim 8, wherein the process gas contains the hydrocarbon gas, and a diluent gas not containing halogen.

11. The plasma processing system according to claim 8, wherein the hydrocarbon gas is CH₄ gas.