Coating apparatus – Gas or vapor deposition – With treating means
Reexamination Certificate
2000-11-07
2003-12-16
Hassanzadeh, Parviz (Department: 1763)
Coating apparatus
Gas or vapor deposition
With treating means
C118S7230ER, C156S345340, C156S345470, C156S345330, C156S345360
Reexamination Certificate
active
06663715
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plasma CVD method of using a plasma CVD apparatus. More particularly, the present invention relates to a plasma CVD apparatus in which a plasma generation region and a substrate processing region are separated and which is suitable for a large area CVD film formation.
2. Description of the Related Art
As one of the plasma CVD apparatuses for forming a film on a substrate while restraining plasma damage, a remote-plasma CVD apparatus is known in which a plasma generation region and a substrate processing region are separated. A method of forming a CVD film using such a remote-plasma CVD apparatus is an important technology as the processing process to make a highly reliable device and a highly efficient device in a semiconductor device process. The remote plasma CVD apparatuses can attain the large sized substrate processes such as a large area flat panel display switching transistor forming process, a drive circuit transistor forming process and a large diameter silicon wafer process. As such a remote plasma CVD apparatus, a parallel plate remote plasma CVD apparatus is disclosed in Japanese Laid Open Patent Application (JP-A-Heisei 5-21393). As shown in FIG. 1, the parallel plate remote plasma CVD apparatus is composed of a high frequency applied electrode 101 and a counter electrode 102 on which a substrate 103 is mounted. A plasma confining electrode 108 as a mesh plate having a plurality of holes is provided between the high frequency applied electrode 101 and the counter electrode 102. Plasma 106 is confined between the high frequency applied electrode 101 and the plasma confining electrode 108. Plasma generation gases 111 are introduced between the high frequency applied electrode 101 and the plasma confining electrode 108. The vacuum chamber 107 is provided with an exhaust port 116.
Such a parallel plate remote plasma CVD apparatus using the plasma generated between parallel plates can uniformly supply radicals necessary to process a substrate in a large area. The apparatus disclosed in the above mentioned Japanese Laid Open Patent Application (JP-A-Heisei 5-21393) is provided with neutral gas injection holes 109 near the passage holes 105 for the radicals 104. The large area uniform process is possible through the reaction of the radicals 104 and the neutral gas 110. For this reason, the parallel plate remote plasma CVD apparatus is considered as a superior technique for forming a silicon oxide film and a nitride silicon film as a gate insulating film of a thin film transistor on a large sized glass substrate, an amorphous silicon film such as an active layer and a gate electrode of the thin film transistor on the large sized glass substrate, and a silicon oxide film and a nitride silicon film as an interlayer insulating film of a transistor device on a large sized silicon substrate.
As mentioned above, the neutral gas injection holes 109 are provided near the radical passage holes 105 and the neutral gas is uniformly supplied on the surface from the neutral gas injection holes 109. At this time, the plasma confining electrode 108 of a hollow structure is used, as disclosed in Japanese Laid Open Patent Application (JP-A-Heisei 5-21393). The plasma confining electrode 108 of the hollow structure is provided with the radical passage holes 105 and the neutral gas passage holes 109 independently, as shown in FIGS. 2 and 3. The radicals 104 and the neutral gas 110 are never mixed in the hollow structure.
As a method of supplying the neutral gas from the outside of a vacuum chamber 107 to the plasma confining electrode 108 of the hollow structure, various methods are considered. In a first method, the neutral gas 110 is supplied from an upper direction into the plasma confining electrode 108 through the plasma region 106 by neutral gas introduction pipes 112 as shown in FIG. 4. Also, in a second method, the neutral gas 110 is supplied from a lateral direction into the plasma confining electrode 108 as shown in FIG. 5. The method disclosed in the above-mentioned Japanese Laid Open Patent Application (JP-A-Heisei 5-21393) is of the latter.
In the first method shown in FIG. 4, the neutral gas 110 can be uniformly injected on the surface of the substrate, if a lot of neutral gas introduction pipes 112 are uniformly provided for the plasma confining electrode 108. In this case, however, the neutral gas introduction pipes 112 pass through the plasma generation region 106. As a result, abnormal discharge 117 is generated easily near the neutral gas introduction pipe on the whole of the plasma confining electrode 108, so that the plasma generating state becomes unstable.
Also, in the second method shown in FIG. 5, most of the gas is injected from the neutral gas injection holes near the connection section of the neutral gas introduction pipe 112 with the plasma confining electrode 108. As a result, because the pressure in the plasma confining electrode 108 of the hollow structure is as low pressure as tens to hundreds mtorr which is equal to a film forming pressure in the substrate processing region, the uniform gas injection on the surface is difficult, as schematically shown in FIG. 6.
To solve the above problem, it would be necessary to arrange such a gas diffusing plate as used in a gas shower head of the conventional parallel plate plasma CVD apparatus, in the inside of the plasma confining electrode 108 of the hollow structure. As shown in FIG. 7, the conventional gas shower head structure is composed of neutral gas introduction pipes 112, a diffusing plate 114 having a plurality of holes uniformly provided on the surface thereof and a gas injection plate 115 having gas injection holes uniformly on the surface thereof. In the conventional parallel plate plasma CVD apparatus, a large number of gas supply pipes can be connected to the gas shower head. Therefore, uniform gas injection is possible even in the structure as shown in FIG. 7. In this case, however, it is impossible to supply a gas to the gas shower head while avoiding the above-mentioned abnormal discharge in the remote plasma CVD apparatus. Also, it is difficult to uniformly inject the neutral gas on the surface of the substrate 103 in the method of using the gas diffusing plate as shown in FIG. 7.
In conjunction with the above description, a plasma CVD apparatus is disclosed in Japanese Laid Open Utility Model Application (JU-A-Heisei 1-86227). In this reference, the plasma CVD apparatus is composed of a box electrode, and a counter electrode. A substrate is provided between the electrodes. The box electrode has a fixed intermediate diffusing plate and a movable intermediate diffusing plate. The diffusing plates have a plurality of holes. By adjusting the position of the movable intermediate diffusing plate, the number of gas passable holes and the area of the gas passage hole are adjusted.
Also, a plasma CVD apparatus disclosed in Japanese Laid Open Utility Model Application (JU-A-Heisei 7-27149). In this reference, the plasma CVD apparatus is composed of an electrode section (2) having electrode plates (3 and 4) parallel to a wafer W and a gas introduction pipe (5). A gas G is introduced through the gas introduction pipe (5), passes through the electrode plates (3 and 4), and is supplied to the wafer W. A gas diffusing pipe (10
a
) is provided in parallel to the electrode plates (3 and 4) to have holes (11) in a radial direction from the gas introduction pipe (5). The gas diffusing pipe (10
a
) is connected to the connection end (5
a
) of the gas introduction pipe (5) and has the closed end.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a plasma CVD apparatus in which it is possible to uniformly inject a neutral gas on a substrate surface.
Another object of the present invention is to provide a plasma CVD apparatus in which abnormal discharge does not occur, even if a neutral gas introduction pipe is inserted into a plasma generation region.
In order to achieve an aspect of the present i
Ikemoto Manabu
Yuda Katsuhisa
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