Coating processes – Spraying – Moving the base
Reexamination Certificate
1999-02-03
2001-03-06
Beck, Shrive (Department: 1762)
Coating processes
Spraying
Moving the base
C427S240000, C118S052000, C118S320000, C118S503000
Reexamination Certificate
active
06197385
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus and a method for coating a coating solution on for example a substrate and forming a soft silicon film.
2. Description of the Related Art
As a method for forming an inter-layer insulation film of a semiconductor device, CVD method and heat oxidizing method are known. In addition, sol-gel method is known. In the sol-gel method, coating solution of which colloid of TEOS (tetraethoxysilane: Si(C
2
H
5
O)
4
) has been dispersed in organic solvent such as ethanol solvent is coated on the front surface of a semiconductor wafer (hereinafter simply referred to as wafer). The coated film is gelated and dried. Thus, a silicon oxide film is obtained. This method has been disclosed in for example Japanese Patent Laid-Open Publication Nos. 8-162450 and 8-59362.
FIGS. 19A
to
19
C show states of denaturation of the coated film in the sol-gel method. When the coating solution is coated on the wafer, particles or colloid
100
of TEOS is dispersed in solvent
200
(see FIG.
19
A). Thereafter, the coated film is exposed to alkali atmosphere. Thus, since TEOS is poly-condensed and hydrolyzed, the coated film is gelated and thereby a mesh structure of TEOS
300
is formed (see FIG.
19
B). Thereafter, solvent contained in the coated film is substituted with another solvent
400
so as to remove moisture of the coating solution (see FIG.
19
C). The coated film is dried. Thus, a soft silicon film is obtained as the coated film. In the solvent substituting process shown in
FIG. 19C
, in addition to removing moisture, with solvent whose surface tension is smaller than that of ethanol, large force is prevented from being applied to the mesh structure of TEOS. Thus, the structure of the film can be prevented from breaking.
When such sol-gel method is applied for a real fabrication line, a coating unit that coats a coating solution to a wafer, a gelating unit that gelates the coated film, and a solvent substituting unit that substitutes solvent contained in the coated film with another solvent are required. In addition, a pre-process unit that performs a preprocess such as a hydrophobic process for a wafer and a baking unit that dries the wafer are required. Moreover, a conveying mechanism that conveys a wafer among these units is required.
After coating solution is coated on a wafer, solvent should be suppressed from evaporating so as to prevent the thickness of the resultant film from decreasing. In addition, after TEOS is gelated until the solvent substituting step is preformed, the solvent should be suppressed from evaporating so as to prevent strong force from being applied to the mesh structure of TEOS.
However, the process time period varies unit by unit. In addition, the process time period also varies corresponding to the unit structure. In other words, in the case that many wafers conveyed with a cassette are successively processed, when a wafer that has been processed in a particular unit is converted to another unit, a waiting time period is required. F or example, a wafer that has been processed in the coating unit may not be converted to the gelating unit, but stayed in the coating unit. Alternatively, a wafer that has been processed in the gelating unit may not be converted to the solvent substituting unit, but stayed in the gelating unit. When such a waiting time period takes place, the solvent on the wafer evaporates. Thus, the film quality deteriorates.
In addition, when a wafer is conveyed from one unit to another unit, the wafer is exposed to air. Thus, when a wafer that has been processed in the coating unit is conveyed to the gelating unit, the solvent on the front surface of the wafer evaporates and thereby the film quality deteriorates.
SUMMARY OF THE INVENTION
The present invention is made from the above-described point of view.
Therefore, an object of the present invention is to provide an apparatus and a method for coating a coating solution of which colloid or particles of a starting substance of a film forming component has been dispersed in solvent to a substrate and for quickly conveying the resultant substrate to the next process so as to obtain an excellent thin film (for example, an inter-layer insulation film).
Another object of the present invention is to provide an apparatus and a method that suppress solvent from evaporating from the front surface of a substrate on which coating solution of which a starting substance of a film forming component has been dispersed in solvent is coated in the case that the substrate is conveyed to the next process so as to obtain an excellent thin film (for example, an interlayer insulation film).
A first aspect of the present invention is an apparatus for forming a film on the front surface of a substrate, comprising a coating portion for coating a coating solution of which particles or collide of a starting substance of a film forming component has been dispersed in first solvent to the front surface of the substrate so as to form a coated film, at least one gelating process portion for gelating particles or collide of the coated film, and a conveying means for loading the substrate to the coating portion, conveying the substrate to the gelating process portion, and unloading the substrate from the gelating process portion, wherein the coating portion causes the substrate to be stayed for a time period adjusted in accordance with a time period after the substrate is loaded from the conveying means to the gelating process portion until the substrate is unloaded from the gelating process portion to the conveying means.
According to the present invention, the staying time period in the coating portion is a rate determiner in the process sequence until the wafer is unloaded from the gelating portion, after the coating solution is coated to the substrate, the substrate is quickly conveyed to the next process. Thus, since the solvent is suppressed from evaporating from the substrate, an excellent thin film can be obtained.
A second aspect of the present invention is an apparatus for conveying a substrate having a coated film of which a coating film containing a starting substance of a film component and solvent has been coated, comprising a substrate conveying member for holding and conveying the substrate, and a vapor supplying means for supplying vapor of the component of the solvent to the front surface of the coated film so as to suppress the solvent contained in the coated film from evaporating.
According to the present invention, when the substrate that has been coated in the coating portion is conveyed to for example the gelating portion by the substrate conveying member, since vapor of a component of the solvent for example ethylene glycol is supplied to the front surface of the coated film, the solvent can be suppressed from evaporating. Thus, an excellent thin film can be obtained.
These and other objects, features and advantages of the present invention will become more apparent in light of the following detailed description of a best mode embodiment thereof, as illustrated in the accompanying drawings.
REFERENCES:
patent: 5571560 (1996-11-01), Lin
patent: 5672205 (1997-09-01), Fujimoto et al.
patent: 5807607 (1998-09-01), Smith et al.
patent: 5858462 (1999-01-01), Yamazaki
patent: 6001416 (1999-12-01), Moriyama et al.
patent: 6001418 (1999-12-01), DeSimone et al.
patent: 8-255750 (1996-10-01), None
Mizutani Yoji
Nagashima Shinji
Takeshita Kazuhiro
Beck Shrive
Calcagni Jennifer
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Tokyo Electron Limited
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