Removal method and processing method

Abstract

A removal method for selectively removing a plurality of metal oxide films formed in a plurality of recesses on a substrate within a processing container comprises and repeats the following steps a plurality of times: exposing the plurality of metal oxide films to BCl3 gas or plasma generated by introducing BCl3 gas; stopping the introduction of BCl3 gas to perform a purging step; exposing the plurality of metal oxide films to plasma generated by introducing an inactive gas; and stopping the introduction of inactive gas to perform a purging step; the step of exposing the plurality of metal oxide films to the plasma involves exposing the plurality of metal oxide films to at least one different plasma generated by a single gas.

Description

[Technical Field] This invention relates to a removal method and a processing method. [Previous Technology] A technique has been proposed that uses a gas containing BCl3 to remove a naturally occurring oxide film formed on the surface of a metal film (see, for example, Patent Documents 1-6). The reason for removing the naturally occurring oxide film formed on the metal film before forming a specific film is to reduce the contact resistance between the metal film and the specific film during the film formation process. However, when the metal films within the multiple holes formed on the substrate are made of multiple different metals, different types of natural oxide films will form on the surface of these multiple metal films. For example, if the multiple metal films consist of metal films that are difficult to form natural oxide films on the surface and metal films that are easy to form natural oxide films on the surface, then it is necessary to selectively etch the natural oxide films on the metal films that are easy to form natural oxide films by using the natural oxide films on the metal films that are more difficult to form natural oxide films on the surface, in order to avoid etching the metal films themselves. [Patent Literature] Patent Document 1: Japanese Patent Application Publication No. 10-298759 Patent Document 2: Japanese Patent Application Publication No. 11-145282 Patent Document 3: Japanese Patent Application Publication No. 11-186226 Patent Document 4: Japanese Patent Application Publication No. 2003-68705 Patent Document 5: Japanese Patent Application Publication No. 2009-16611 Patent Document 6: Japanese Patent Application Publication No. 2010-206050 [Summary of the Invention] In view of the above-mentioned problems, in one aspect, the object of the present invention is to selectively remove multiple metal oxide films. To address the aforementioned issues, a method is provided that selectively removes multiple types of metal oxide films formed in multiple recesses on a substrate within a processing container. This method comprises and repeats the following steps multiple times: exposing the multiple types of metal oxide films to BCl3 gas or plasma generated by introducing BCl3 gas; stopping the introduction of BCl3 gas and performing a purging process; exposing the multiple types of metal oxide films to plasma generated by introducing an inactive gas; and stopping the introduction of the inactive gas and performing a purging process. The step of exposing the multiple types of metal oxide films to the plasma involves exposing the multiple types of metal oxide films to at least one different plasma generated by a single gas. Other objects, features and advantages of the present invention will become more apparent from the accompanying drawings and the following detailed description. [Simplified Explanation of the Diagram] Figure 1 is a diagram showing the system that forms the metal wiring. Figure 2 is a schematic cross-sectional view of a metal oxide film removal device with a related implementation type. Figure 3 is a diagram showing an example of ALE processing related to an implementation type. Figure 4 is a diagram illustrating an example of a selective removal process for multiple metal oxide films related to an implementation type. Figure 5 is a timing diagram showing an example of selective removal (including cleaning) of multiple metal oxide films related to an implementation type. Figure 6 is a diagram illustrating an example of a selective removal process (including cleaning) of multiple metal oxide films related to an implementation type. Figure 7 is a diagram showing an example of ALE processing related to an implementation type. Figure 8 is a diagram showing an example of the ALE processing effect related to an implementation type. Figure 9 is a diagram illustrating the cleaning process following an ALE treatment of a specific implementation type. Figure 10 is a diagram showing an example of the cleaning treatment effect related to a certain implementation type. Figure 11 is a diagram showing an example of a metal oxide film removal apparatus related to a modified embodiment. Figure 12 is a timing diagram showing an example of selective removal (including cleaning) of multiple metal oxide films related to a variation of an embodiment. Figure 13 is a diagram illustrating an example of a process related to an implementation type, from the selective removal of multiple metal oxide films to the embedding of metal wiring.

Implementation Method

Claims

1. A removal method for selectively removing a plurality of metal oxide films formed in a plurality of recesses on a substrate within a processing container, comprising repeating the following steps a plurality of times: exposing the plurality of metal oxide films to BCl3 gas or plasma generated by introducing BCl3 gas; stopping the introduction of BCl3 gas for purging; exposing the plurality of metal oxide films or the metal film beneath the metal oxide films to plasma generated by introducing an inactive gas; and stopping the introduction of the inactive gas for purging; the step of exposing the plurality of metal oxide films or the metal film beneath the metal oxide films to the plasma includes a second step, the second step being to expose the plurality of metal films to two different plasmas generated by each of a single gas containing a plurality of gases containing an inactive gas; adjusting the gap between the lower electrode and the upper electrode opposite the lower electrode by means of an adjustment mechanism that adjusts the height of the mounting stage used to mount the substrate, i.e., the lower electrode.

2. The removal method according to claim 1, wherein the step of exposing at least one of the plurality of metal oxide films or metal films to the plasma further includes a first step, wherein the first step is to expose the plurality of metal oxide films to a plasma generated by a single gas of inactive gas.

3. The removal method as described in claim 2, wherein the first step uses Ar gas or N2 gas; and the second step uses H2 gas and Ar gas.

4. The removal method according to claim 3, wherein the second step is to expose the plurality of metal films to plasma generated by a single gas of H2 after exposing the plurality of metal films to plasma generated by a single gas of Ar.

5. The removal method according to claim 3, wherein the second step involves alternately exposing the plurality of metal films to plasma generated by a single gas of H2 and plasma generated by a single gas of Ar.

6. The removal method as claimed in claim 3, wherein in the second step, plasma generated by a single gas of H2 and / or plasma generated by a single gas of Ar are applied intermittently.

7. The removal method according to claim 3, wherein in each of the steps of stopping the introduction of the BCl3 gas for purging and stopping the introduction of the inactive gas for purging, Ar gas is stored in a storage tank; and in both the steps of stopping the introduction of the BCl3 gas for purging and stopping the introduction of the inactive gas for purging, the stored Ar gas is supplied.

8. The removal method according to claim 2, wherein in the first step, high-frequency power is applied to the upper electrode and the lower electrode; and in the second step, high-frequency power is applied to the lower electrode.

9. The removal method as claimed in claim 8, wherein the high-frequency power applied in the first step is less than the high-frequency power applied in the second step.

10. The removal method according to claim 1, wherein in the step of exposing the plurality of metal oxide films to the plasma generated by introducing the BCl3 gas, a high-frequency power is applied to the upper electrode.

11. In the removal method of claim 1, the height of the lower electrode is adjusted by means of the adjustment mechanism in the steps of stopping the introduction of the BCl3 gas for cleaning and stopping the introduction of the inactive gas for cleaning.

12. The removal method according to claim 1, wherein in the first step the height of the lower electrode is adjusted by the adjustment mechanism so that the gap between the upper electrode and the lower electrode is wider than in the second step.

13. A processing method for burying metal wiring within recesses, comprising the steps of: selectively removing a plurality of metal oxide films formed in a plurality of recesses on a substrate within a processing container; selectively removing the plurality of metal oxide films and then covering the plurality of recesses with a metal barrier film; and burying the metal wiring within the plurality of recesses covered by the metal barrier film; all of these steps are performed without exposing the substrate within the processing container to the atmosphere; the selective removal of the plurality of metal oxide films includes repeating the following steps a plurality of times: exposing the plurality of metal oxide films to BCl3 gas or introducing BCl3 gas to form a gas. The process includes: a plasma process; a cleaning process by stopping the introduction of BCl3 gas; a process of exposing the plurality of metal oxide films or the metal film under the metal oxide film to the plasma generated by introducing inactive gas; and a cleaning process by stopping the introduction of inactive gas; the process of exposing the plurality of metal oxide films or the metal film under the metal oxide film to the plasma includes a second process, which is to expose the plurality of metal films to two different plasmas generated by each of a plurality of gases containing inactive gas; and adjusting the gap between the lower electrode and the upper electrode facing the lower electrode by adjusting the height of the mounting stage used to mount the substrate, i.e., the lower electrode.

14. The processing method of claim 13, wherein the metal barrier film covering the plurality of recesses is titanium nitride (TiN) or tantalum nitride (TaN).

15. The processing method as described in claim 13, wherein the metal wiring used to fill the recess is ruthenium.

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