This is a National Phase Application filed under 35 U.S.C. 371 as a national stage of PCT/JP2018/031810, filed Aug. 28, 2018, an application claiming the benefit of Japanese Application No. 2017-174287, filed Sep. 11, 2017, the content of each of which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a technology of forming an insulating film that is a silicon oxide-containing coated film and is hardened by a cross-linking reaction.

BACKGROUND

There is a process of forming an insulating film such as a silicon oxide film in the processes of manufacturing semiconductor devices. The insulating film is formed, for example, by plasma CVD or by applying a coating liquid. An insulating film formed by plasma CVD has an advantage that a high quality film is obtained because it is dense, but embeddability is poor. Accordingly, for example, the insulating film is not suitable when an insulator is embedded in a fine groove called a Shallow Trench Isolation (STI). Accordingly, for example, it is required to gradually embed the insulating film such that a gap is not generated, by repeating plasma CVD and etch-back, so the process of forming a film is complicated or a large-scale apparatus is required to perform vacuum processing.

Further, according to a method of forming an insulating film by applying a coating liquid to a semiconductor wafer (hereafter, referred to as a ‘wafer’) through spin coating, etc., and then curing the coated film, embeddability is good, so it is easy to fill even fine patterns such as an STI with an insulating film. Further, there is an advantage that processing can be performed in an ordinary pressure atmosphere, but there is problem that the strength of the film is relatively low. Accordingly, the strength of the film is increased, for example, by performing a heat treatment (curing) on a coated film at 600 to 800 degrees C.

However, according to a miniaturization of the pattern, there is a request for suppressing a thermal history for a semiconductor device to be manufactured as low as possible. Therefore, for example, when an interlayer insulating film is formed, the temperature cannot be increased over 400 degrees C. in light of migration of copper (Cu) wires, diffusion of Cu, etc. Therefore, the method of forming an insulating film by applying a coating liquid cannot be applied to an interlayer insulating film due to the high curing temperature.

A technology of forming an insulating film by forming a coated film, heating the coated film at a low temperature, and then processing the coated film at a high temperature in a water vapor atmosphere is described in Patent Document 1, but it does not solve the problems solved by the technology of the present disclosure.

Prior Art Documents

Patent Documents

Patent Document 1: Japanese Laid-Open Patent Publication No. 2012-174717.

SUMMARY

The purpose of the present disclosure is to provide a technology that achieves a good quality of a film when forming an insulating film containing a silicon oxide as a coated film on a substrate.

According to one embodiment of the present disclosure, there is provided a method for a method of forming an insulating film, the method including: a process of forming a coated film on a substrate by applying a coating liquid, which is obtained by dissolving a precursor for forming an insulating film containing silicon oxide in a solvent, to the substrate; a solution volatilization process of volatilizing the solvent in the coated film; subsequently, an energy supply process of supplying energy to the coated film in a low-oxygen atmosphere having a concentration of oxygen lower than an atmospheric atmosphere to form dangling bonds at molecular groups constituting the precursor; a process of forming, on a surface of the coated film, a protective film for suppressing oxidation of the dangling bonds in the coated film due to the atmospheric atmosphere; and subsequently, a curing process of forming the insulating film by heating the substrate and crosslinking the precursor.

According to another embodiment of the present disclosure, there is provided an apparatus for processing a substrate, including: a coating module configured to form a coated film on a substrate by applying a coating liquid, which is obtained by dissolving a precursor for forming an insulating film containing silicon oxide in a solvent, to the substrate; a solvent volatilization module configured to volatilize the solvent in the coated film; an energy supply module configured to supply energy to the coated film in which the solvent has been volatilized, in a low-oxygen atmosphere having a concentration of oxygen lower than an atmospheric atmosphere so as to activate the precursor; a protective film formation module configured to form a protective film on the coated film to which the energy has been supplied; and a substrate transfer mechanism configured to transfer the substrate between the respective modules.

According to yet another embodiment of the present disclosure, there is provided a system for processing a substrate, including: an apparatus for processing a substrate which includes: a load/unload port configured to load/unload the substrate accommodated in a transfer container; a coating module configured to form a coated film on the substrate by applying a coating liquid, which is obtained by dissolving a precursor for forming an insulating film containing silicon oxide in a solvent, to the substrate; a solvent volatilization module configured to volatilize the solvent in the coated film; an energy supply module configured to supply energy to the coated film in which the solvent has been volatilized, in a low-oxygen atmosphere having a concentration of oxygen lower than an atmospheric atmosphere so as to activate the precursor; a protective film formation module configured to form a protective film on the coated film to which the energy has been supplied; and a substrate transfer mechanism configured to transfer the substrate between the respective modules and the load/unload port; a heat treatment apparatus configured to form the insulating film by heating the substrate processed in the apparatus for processing the substrate and crosslinking the precursor; and a container transfer mechanism configured to transfer the transfer container between the load/unload port of the apparatus for processing the substrate and the curing apparatus.

According to the present disclosure, a coating liquid containing a precursor of an insulating film containing a silicon oxide is applied to a substrate, a solvent in the coating liquid is volatilized, and energy is supplied to the coated film in a low-oxygen atmosphere before a curing process is performed. Accordingly, dangling bonds are easily produced at portions that are hydrolyzed in the precursor. In the curing process, hydroxyl groups are bonded to silicon at molecular groups constituting the precursor by hydrolysis at first, and then crosslinking is performed by dehydration condensation of the hydroxyl groups at the molecular groups. However, by forming dangling bonds in advance at silicon that is the portions that are hydrolyzed, production efficiency of the hydroxyl groups is increased. That is, since the energy for hydrolysis decreases, the portions remaining without hydrolyzing decreases even if the curing process is performed at a low temperature. As a result, dehydration condensation efficiently occurs, so a crosslinking rate is improved and it is possible to form a dense (good-quality) insulating film.

Further, it is possible to suppress reaction of dangling bonds before the curing process by forming a protective film on the surface of a coated film after supplying energy to the coated film, whereby the quality of the coated film is improved.

