US-20260130149-A1 - OXIDE FILM ETCHING METHOD AND SUBSTRATE PROCESSING APPARATUS

US20260130149A1US 20260130149 A1US20260130149 A1US 20260130149A1US-20260130149-A1

Abstract

An oxide film etching method includes: forming a protective film of a metal or a metal nitride that does not contain silicon so as to cover a protection target film, among the protection target film containing silicon and a silicon-containing oxide film exposed on a surface of a substrate; supplying, to the substrate, a mixed gas including a hydrogen fluoride gas and an ammonia gas to react with the silicon-containing oxide film, and modifying the oxide film to generate a reaction product; and sublimating and removing the reaction product.

Inventors

Takashi Kobayashi
Kensaku Tanaka

Assignees

TOKYO ELECTRON LIMITED

Dates

Publication Date: 20260507
Application Date: 20251218
Priority Date: 20230626

Claims (20)

1 . An oxide film etching method comprising: forming a protective film of a metal or a metal nitride that does not contain silicon so as to cover a protection target film, among the protection target film containing silicon and a silicon-containing oxide film exposed on a surface of a substrate; supplying, to the substrate, a mixed gas including a hydrogen fluoride gas and an ammonia gas to react with the silicon-containing oxide film, and modifying the oxide film to generate a reaction product; and sublimating and removing the reaction product.
2 . The oxide film etching method of claim 1 , wherein the protection target film constitutes a side surface of a recess formed in the surface of the substrate, and the oxide film constitutes a bottom surface of the recess.
3 . The oxide film etching method of claim 2 , wherein the protective film is formed by a chemical vapor deposition method without using plasma.
4 . The oxide film etching method of claim 3 , wherein the forming the protective film by the chemical vapor deposition method includes repeatedly performing: supplying, to the substrate, a raw material gas containing a raw material of the metal; and supplying, to the substrate, a reaction gas that precipitates the metal from the raw material or a reaction gas that nitrides the metal.
5 . The oxide film etching method of claim 3 , wherein the protective film is selectively formed on the protection target film by virtue of an incubation time in the forming the protective film by the chemical vapor deposition method being longer for the oxide film than for the protection target film.
6 . The oxide film etching method of claim 1 , wherein the protection target film is a silicon nitride film containing oxidized silicon.
7 . The oxide film etching method of claim 1 , wherein the protective film contains a metal selected from titanium, tungsten, or ruthenium.
8 . The oxide film etching method of claim 1 , comprising, after the sublimating and removing the reaction product: forming a contact metal film on the surface of the substrate; and forming a cap film so as to cover the contact metal film.
9 . The oxide film etching method of claim 8 , comprising: removing the protective film after the sublimating and removing the reaction product and before the forming the contact metal film.
10 . A substrate processing apparatus that processes a substrate, comprising: a first processing module including a processing container including a stage on which the substrate is placed, and a film formation gas supply configured to supply a film formation gas into the processing container; a second processing module including a processing container including a stage on which the substrate is placed, and a mixed gas supply configured to supply a mixed gas including a hydrogen fluoride gas and an ammonia gas into the processing container; a third processing module including a processing container including a stage on which the substrate is placed, and a sublimation processor configured to carry out at least one of heating of the substrate or reduced-pressure exhaust within the processing container; and a controller, wherein the controller is configured to output a control signal to execute: a processing step of supplying the film formation gas into the processing container of the first processing module while the substrate, in which a protection target film containing silicon and a silicon-containing oxide film are exposed on a surface of the substrate, is placed on the stage of the first processing module, and forming a protective film of a metal or a metal nitride that does not contain silicon so as to cover the protection target film; a processing step of supplying the mixed gas into the processing container of the second processing module, while the substrate is placed on the stage of the second processing module, to react with the silicon-containing oxide film, and modifying the oxide film to generate a reaction product; and a processing step of sublimating and removing the reaction product from the substrate, on which the reaction product has been generated, by the sublimation processor while the substrate is placed on the stage of the third processing module.
11 . The substrate processing apparatus of claim 10 , wherein the protection target film constitutes a side surface of a recess formed in the surface of the substrate, and the oxide film constitutes a bottom surface of the recess.
12 . The substrate processing apparatus of claim 11 , wherein the film formation gas forms the protective film by a chemical vapor deposition method without using plasma.
13 . The substrate processing apparatus of claim 12 , wherein the film formation gas supply includes a raw material gas supply configured to supply a raw material gas containing a raw material of the metal, and a reaction gas supply configured to supply, to the substrate, a reaction gas to precipitate the metal from the raw material or to nitride the metal, and wherein the controller is configured to output a control signal to repeatedly execute supply of the raw material gas and supply of the reaction gas to the substrate during supply of the film formation gas.
14 . The substrate processing apparatus of claim 12 , wherein the film formation gas has a characteristic that an incubation time for the oxide film is longer than an incubation time for the protection target film in the forming the protective film by the chemical vapor deposition method, and wherein the controller is configured to output a control signal to stop supply of the film formation gas after the protective film has been formed on the protection target film and before the protective film is formed on the oxide film, in order to selectively form the protective film on the protection target film.
15 . The substrate processing apparatus of claim 10 , wherein the protection target film is a silicon nitride film containing oxidized silicon.
16 . The substrate processing apparatus of claim 10 , wherein the protective film contains a metal selected from titanium, tungsten, or ruthenium.
17 . The substrate processing apparatus of claim 10 , comprising: a fourth processing module including a processing container including a stage on which the substrate is placed, and a contact film formation gas supply configured to supply, into the processing container, a contact film formation gas to form a contact metal film; and a fifth processing module including a processing container including a stage on which the substrate is placed, and a cap film formation gas supply configured to supply, into the processing container, a cap film formation gas to form a cap film, wherein the controller is configured to output a control signal to execute, after the processing step of sublimating and removing the reaction product: a processing step of placing the substrate on the stage of the fourth processing module and supplying the contact film formation gas into the processing container, thus forming the contact metal film on the surface of the substrate; and a processing step of placing the substrate on the stage of the fifth processing module and supplying the cap film formation gas into the processing container, thus forming the cap film so as to cover the contact metal film.
18 . The substrate processing apparatus of claim 17 , wherein the third processing module or the fourth processing module includes a cleaning gas supply configured to supply, into the processing container, a cleaning gas to remove the protective film, and wherein the controller is configured to output a control signal to execute: a processing step of supplying the cleaning gas into the processing container to remove the protective film, after the processing step of sublimating and removing the reaction product and before the processing step of forming the contact metal film.
19 . The substrate processing apparatus of claim 17 , wherein the film formation gas and the cap film formation gas are a common gas, and wherein the substrate processing apparatus comprises a common processing module shared by the first processing module and the fifth processing module.
20 . The substrate processing apparatus of claim 17 , comprising: a vacuum transport chamber to which the processing container of the first processing module to the processing container of the fifth processing module are connected; and a substrate transporter disposed within the vacuum transport chamber, wherein the controller is configured to output a control signal to execute: a transport step of transporting the substrate by the substrate transporter through the vacuum transport chamber to the processing container of one of the first processing module to the fifth processing module in which the processing step is carried out.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a bypass continuation application of International Patent Application No. PCT/JP2024/021387 having an international filing date of Jun. 12, 2024 and designating the United States, the international application being based upon and claiming the benefit of priority from Japanese Patent Application No. 2023-104385, filed on Jun. 26, 2023, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD The present disclosure relates to an oxide film etching method and a substrate processing apparatus. BACKGROUND In a manufacturing process of semiconductor devices, a method is known in which a silicon oxide film, which is a natural oxide film present on a surface of a semiconductor wafer (hereinafter referred to as “wafer”) serving as a substrate, is dry-etched without using plasma. This dry etching method is performed, for example, by a chemical oxide removal (COR) process, which modifies a silicon oxide film to generate a reaction product, and a post heat treatment (PHT) process, which sublimates and removes the reaction product. For example, Patent Document 1 describes a wafer structure on which these processes are performed. Specifically, an HDP-SiO2 film formed by a bias high-density plasma CVD (HDP-CVD) method is provided as an interlayer insulating film on an Si layer, and a contact hole reaching the Si layer is provided in the HDP-SiO2 film. It is described that an SiN film, which is an insulator, is provided on a sidewall of the contact hole, and a sacrificial oxide film, which is a natural oxide film provided on a bottom of the contact hole, is removed by the aforementioned processes. PRIOR ART DOCUMENTS Patent Documents Patent Document 1: Japanese U.S. Pat. No. 6,161,972 SUMMARY According to one embodiment of the present disclosure, an oxide film etching method includes: forming a protective film of a metal or a metal nitride that does not contain silicon so as to cover a protection target film, among the protection target film containing silicon and a silicon-containing oxide film exposed on a surface of a substrate; supplying, to the substrate, a mixed gas including a hydrogen fluoride gas and an ammonia gas to react with the silicon-containing oxide film, and modifying the oxide film to generate a reaction product; and sublimating and removing the reaction product. BRIEF DESCRIPTION OF DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the present disclosure. FIG. 1A is a longitudinal cross-sectional side view of a recess formed in a wafer according to an embodiment of the present disclosure. FIG. 1B is a longitudinal cross-sectional side view of a recess in a comparative embodiment. FIG. 2A is a first longitudinal cross-sectional side view of the recess according to the embodiment. FIG. 2B is a second longitudinal cross-sectional side view of the recess according to the embodiment. FIG. 2C is a third longitudinal cross-sectional side view of the recess according to the embodiment. FIG. 2D is a fourth longitudinal cross-sectional side view of the recess according to the embodiment. FIG. 2E is a fifth longitudinal cross-sectional side view of the recess according to the embodiment. FIG. 3 is a plane view of a substrate processing apparatus according to the embodiment. FIG. 4 is a longitudinal cross-sectional side view illustrating a first processing module of the substrate processing apparatus. FIG. 5 is a longitudinal cross-sectional side view illustrating a second processing module of the substrate processing apparatus. FIG. 6 is a longitudinal cross-sectional side view illustrating a third processing module of the substrate processing apparatus. FIG. 7 is a graph illustrating experimental results of a preliminary test. FIG. 8 is an SEM image illustrating experimental results of an example. DETAILED DESCRIPTION Reference will now be made in detail to various embodiments, examples of which are illustrated in the accompanying drawings. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be apparent to one of ordinary skill in the art that the present disclosure may be practiced without these specific details. In other instances, well-known methods, procedures, systems, and components have not been described in detail so as not to unnecessarily obscure aspects of the various embodiments. In describing an embodiment of an oxide film etching method according to the present disclosure, a configuration of a wafer W, which is a workpiece substrate of the method, is described. FIG. 1A is a longitudinal cross-sectional side view illustrating a portion of a surface l