Metal oxide film formation method
Disclosed herein in a method of forming a metal oxide film, which can provide a high-quality metal oxide film while enhancing production efficiency. The method includes the steps of: turning a raw-material solution having a metallic element into a mist, to obtain a raw-material solution mist; turning a reaction aiding solution into a mist, to obtain an aiding-agent mist; feeding the raw-material solution mist and the aiding-agent mist into a mixing vessel, thereby mixing the raw-material solution mist and the aiding-agent mist, to obtain a mixed mist; and feeding the mixed mist onto a back surface of a substrate which is heated, to obtain a metal oxide film.
1. A method of forming a metal oxide film, the method comprising:
(a) turning a raw-material solution comprising a metallic element into a mist, to obtain a raw-material solution mist, in a first vessel;
(b) turning a reaction aiding solution comprising a reaction aiding agent for said metallic element into a mist, to obtain an aiding-agent mist, in a second vessel provided independently of said first vessel;
(c) mixing said raw-material solution mist and said aiding-agent mist, to obtain a mixed mist, in a mixing vessel which receives said raw-material solution mist and said aiding-agent mist via first and second paths provided independently of each other; and
(d) feeding said mixed mist obtained in (c) onto one main surface of a substrate in a reactor vessel while heating said substrate, to form a metal oxide film comprising said metallic element on said one main surface of said substrate,
wherein said mixing vessel comprises:
a vessel body;
first and second mist feeders which are connected to said first and second paths and are configured to feed said raw-material solution mist and said aiding-agent mist into said vessel body; and
a mist extraction unit, comprising a mixed-mist input port provided inside said vessel body and a mixed-mist output port provided outside said vessel body, and configured to receive said mixed mist from said mixed-mist input port and extract said mixed mist at said mixed-mist output port; wherein
said mixed mist provided from said mixed-mist output port is fed into said reactor vessel via a third path;
said vessel body comprises a mixing path configured to guide said raw-material solution mist and said aiding-agent mist, which are fed from said first and second mist feeders, to said mixed-mist input port while circulating said raw-material solution mist and said aiding-agent mist;
said first and second mist feeders are provided at the same height as formed in said vessel body; and
said mixed-mist input port is provided at a height as formed, which is less than that of said first and second mist feeders.
2. The method according to claim 1 , wherein:
said vessel body has a cylindrical shape;
said mist extraction unit is provided in a central portion of said vessel body in plan view, has a cylindrical shape with a hollow portion, comprises said mixed-mist input port in a lower surface, and comprises said mixed-mist output port in an upper surface; and
said mixing path is formed in a shape of a circumference in plan view by a space between an inner side surface of said vessel body and an outer side surface of said mist extraction unit.
3. The method according to claim 2 , wherein said first and second mist feeders are provided so as to feed said raw-material solution mist and said aiding-agent mist along a tangent of said inner side surface of said vessel body.