FIELD OF THE INVENTION

The present invention relates to an oxide film forming device for forming an oxide film on a workpiece by supplying to the workpiece a raw material gas containing a constituent element of the oxide film.

BACKGROUND ART

On organic materials for use in packaging applications, electronic components, flexible devices and the like, it is common to form inorganic films for surface protection and functionality addition. Further, the flexibilization of various electronic devices is being studied where it is required to form the electronic devices on e.g. organic films. For these reasons, there have been made studies on low-temperature film forming techniques capable of forming films on low heat-resistant substrates such as organic films.

As film forming techniques, chemical vapor deposition (CVD) and physical vapor deposition (PVD) are known. These film forming techniques have been used for the formation of various insulating films, conductive films etc. in the manufacturing processes of fine electronic devices. In general, the chemical vapor deposition is superior in terms of the film deposition rate and covering property.

In the chemical vapor deposition, a film is formed on a workpiece by reacting a raw material gas containing a film constituent element-containing compound (such as, for example, silane (that is a generic name for hydrogen silicate), TEOS (tetraethyl orthosillicate), TMA (trimethyl aluminum) or tungsten fluoride (WF6)) with the addition of a reactive gas and depositing the resulting reaction product on the workpiece. This chemical vapor deposition technique is performed under high-temperature conditions of several hundreds ° C. or higher in order to promote the reaction between the gases and to improve the quality of the film on the workpiece. In other words, the chemical vapor disposition is difficult to perform under low-temperature conditions. The temperature of the chemical vapor deposition often exceeds the heat resistant temperatures of organic materials.

As an example of the application of a high-concentration ozone gas to the chemical vapor deposition technique, there is known a method by which a SiO2film is formed on a substrate with the use of a high-concentration ozone gas and a TEOS gas under high-temperature conditions of several hundreds ° C. or higher (see Patent Document 1).

In order to form a film with good quality by chemical vapor deposition under low-temperature conditions, it is necessary to introduce a reactive species which has a high chemical reactivity even under low-temperature conditions. For example, there are known: a method in which a coating film deposited on a workpiece is oxidized at a temperature of 100° C. or lower (see Patent Document 2); and a method in which an ashing reaction for removal of organic substances is conducted at room temperature (see Patent Documents 3 and 4). Each of these methods realizes a film forming process at a temperature of 200° C. or lower with the use of a reactive species generated through reaction of high-concentration ozone and unsaturated hydrocarbon.

PRIOR ART DOCUMENTS

Patent Documents

Patent Document 1: Japanese Laid-Open Patent Publication No. 2007-109984

Patent Document 2: Japanese Laid-Open Patent Publication No. 2013-207005

Patent Document 3: Japanese Laid-Open Patent Publication No. 2008-294170

Patent Document 4: Japanese Laid-Open Patent Publication No. 2009-141028

Patent Document 5: Japanese Laid-Open Patent Publication No. 2009-191311

Non-Patent Documents

Non-Patent Document 1: Meidensha Corporation, Homepage, Internet, News Releases 2018, “Meiden Developed Technology for Oxide Film Formation at Room Temperature with Use of Pure Ozone” (online), Jul. 31, 2019

SUMMARY OF THE INVENTION

As a result of extensive researches, the present inventors found a method of forming an oxide film on a workpiece by reacting a CVD raw material gas with a reactive species generated through reaction of an ozone gas and an unsaturated hydrocarbon (see Non-Patent Document 1).

In this method, the CVD film forming process takes place in the vicinity of where the ozone gas, the unsaturated hydrocarbon and the raw material gas are mixed together. There is hence a possibility that a thickness deviation occurs in the oxide film formed on the workpiece.

The present invention has been made in view of the above circumstance. It is accordingly an object of the present invention to provide a technique for, during formation of an oxide film on a workpiece by reaction of an ozone gas, an unsaturated hydrocarbon gas and a raw material gas, reducing a deviation in the thickness distribution of the oxide film.

In accordance with one aspect of the present invention to achieve the above object, there is provided an oxide film forming device for forming an oxide film on a workpiece, comprising: a treatment furnace in which the workpiece is placed; and a shower head arranged facing a treatment target surface of the workpiece, wherein the shower head comprises first holes for supplying an ozone gas to the workpiece and second holes for supplying to the workpiece an unsaturated hydrocarbon gas, a raw material gas containing a Si element or metal element which is a constituent element of the oxide film, or a mixed gas of the unsaturated hydrocarbon gas and the raw material gas, wherein a gas supply surface of the shower head is opposed to the treatment target surface of the workpiece at a distance of 1 mm to 100 mm away from the treatment target surface, wherein the first holes and the second holes have a diameter larger than or equal to 0.1 mm and smaller than or equal to 10 mm, and wherein an interval between adjacent ones of the first holes and an interval between adjacent ones of the second holes are larger than or equal to 1 mm and smaller than or equal to 100 mm.

The treatment furnace may comprise a first gas supply port for supplying therethrough the ozone gas and a second gas supply port for supplying therethrough the unsaturated hydrocarbon gas, the raw material gas or the mixed gas, with a first gas buffer space fowled between the first gas supply port and the shower head to allow diffusion of the ozone gas and a second gas buffer space formed between the second gas supply port and the shower head to allow diffusion of the unsaturated hydrocarbon gas, the raw material gas or the mixed gas.

The first holes may be evenly spaced in a rectangular grid arrangement in two directions perpendicular to each other along the treatment target surface; and the second holes may be evenly spaced in a rectangular grid arrangement, in directions respectively parallel to the two directions, at positions displaced from the first holes along the treatment target surface.

The first holes may be provided along an outer periphery of the shower head.

The shower head may be in the four of a plate and detachably disposed in the treatment furnace.

In accordance with another aspect of the present invention to achieve the above object, there is provided an oxide film forming device for forming an oxide film on a workpiece, comprising: a treatment furnace in which the workpiece is placed; and a shower head arranged facing a treatment target surface of the workpiece, wherein the shower head comprises first slits for supplying an ozone gas to the workpiece and second slits for supplying to the workpiece an unsaturated hydrocarbon gas, a raw material gas containing a Si element or metal element which is a constituent element of the oxide film, or a mixed gas of the unsaturated hydrocarbon gas and the raw material gas, wherein the first slits and the second slits are alternately arranged side by side in a short-dimension direction of the slits, wherein a gas supply surface of the shower head is opposed to the treatment target surface of the workpiece at a distance of 1 mm to 100 mm away from the treatment target surface, wherein the first slits and the second slits have a slit width larger than or equal to 0.1 mm and smaller than or equal to 10 mm, and wherein an interval between slit centers of adjacent ones of the first slits and an interval between slit centers of adjacent ones of the second slits are larger than or equal to 1 mm and smaller than or equal to 100 mm.

The present invention produces the effect of, at the time of forming the oxide film on the workpiece by reaction of the ozone gas, the unsaturated hydrocarbon gas and the raw material gas, reducing a deviation in the thickness distribution of the oxide film.

