JP4087234B2 - Plasma processing apparatus and plasma processing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma processing apparatus, and more particularly to a technique for processing a processing object by introducing a plasma generating gas and a reactive gas into a vacuum chamber.
[0002]
[Prior art]
Reference numeral 100 in FIG. 6 denotes a conventional plasma processing apparatus. Here, a parallel plate type plasma CVD apparatus will be described as an example.
[0003]
The plasma processing apparatus 100 includes a vacuum chamber 110 and first and second discharge electrodes 101 and 102 disposed in the vacuum chamber 110.
[0004]
The first discharge electrode 101 is disposed on the ceiling side of the vacuum chamber 110, and the second discharge electrode 102 is disposed at a position immediately below the first discharge electrode 101.
[0005]
The first discharge electrode 101 is connected to the high-frequency power source 105 via the matching box 14, and the second discharge electrode 102 and the vacuum chamber 110 are connected to the ground potential.
[0006]
The first discharge electrode 101 is connected to a gas source 106, and the vacuum chamber 110 is connected to an evacuation system 107. The vacuum chamber 110 is evacuated to a predetermined pressure, and is placed on the second discharge electrode 102. When the raw material gas and the plasma gas are introduced from the gas source 106 and the high frequency voltage is applied to the first discharge electrode 101 with the processing object 103 disposed, the first discharge electrode 101 and the second discharge electrode 102 A plasma is formed between them, and a thin film is formed on the surface of the processing object 103 by the activated source gas.
[0007]
For example, when a substrate such as a glass substrate is used as the object to be processed and silane gas is introduced as the source gas, an a-Si: H thin film can be formed on the substrate surface at a deposition rate of 20 to 30 liters / second. .
[0008]
However, in order to increase the deposition rate in the plasma processing apparatus 100 configured as described above, when the amount of high-frequency power is increased, the gas phase reaction between the source gases generated in the plasma becomes dominant and the film structure becomes uneven. Become.
[0009]
In addition, the incident energy when ions generated in the plasma are incident on the growing thin film increases as the amount of high-frequency power is increased, and defects tend to occur in the film.
[0010]
For the reasons described above, the high-frequency power cannot be increased to improve the deposition rate.
[0011]
On the other hand, there are attempts to improve the deposition rate by using disilane or trisilane as a raw material gas instead of silane, but these gases are dangerous and difficult to handle, and are expensive and have high purity. But there is a problem. Therefore, it is unsuitable for use in mass production equipment.
[0012]
Further, the parallel plate type plasma processing apparatus 110 as described above is also used for etching. However, even when an attempt is made to improve the etching rate by increasing the amount of high-frequency power, non-uniform etching occurs. There's a problem.
[0013]
An apparatus using the same first and second discharge electrodes as the apparatus of the present invention is described in JP-A No. 2000-31121.
[Patent Document 1]
JP 2000-31121 A
[Problems to be solved by the invention]
The present invention was created in order to solve the above-described problems of the prior art, and an object thereof is to provide a plasma processing apparatus having a high processing speed and high uniformity.
[0015]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that a vacuum chamber, first and second discharge electrodes which are arranged to face each other in the vacuum chamber and form a discharge space, and the discharge space. The first gas inlet generated in the discharge space by the first introduction port for introducing the first gas and the high-frequency voltage applied to the second discharge electrode is converted into the vacuum chamber. A plasma processing apparatus having a discharge port that discharges toward a position where the object to be processed is disposed, the position being different from the discharge space in the vacuum chamber, wherein the object to be processed is disposed A stabilizing electrode electrically connected to the first discharge electrode in a net-like shape through which the plasma of the first gas can pass is provided at a position between the discharge position and the discharge port, and the stabilization a position between the position where the processing object and the electrodes are placed, the Second inlet is arranged to introduce a gas, the rare gas is introduced as the first gas, a thin film material gas having a reactive as the second gas is adapted to be introduced, said first The second gas introduced from the second introduction port is a plasma processing apparatus configured to be sprayed onto the processing object .
According to a second aspect of the invention, the second discharge electrode is a plasma processing apparatus according to claim 1 surrounded by the first discharge electrodes.
According to a third aspect of the present invention, in the vacuum chamber, a high-frequency electrode to which a high-frequency voltage is applied is disposed, and the object to be treated is disposed on the high-frequency electrode. The plasma processing apparatus according to the item.
According to a fourth aspect of the present invention, the vacuum chamber, the first and second discharge electrodes that are disposed to face each other in the vacuum chamber and form a discharge space, and the first gas are introduced into the discharge space. And a discharge port for discharging the plasma of the first gas generated in the discharge space toward the position where the object to be processed is disposed in the vacuum chamber, In a position different from the discharge space in the vacuum chamber and between the position where the object to be processed is disposed and the discharge port, the first gas plasma is allowed to pass through. A stabilization electrode electrically connected to the first discharge electrode is provided, and a second gas is introduced to a position between the stabilization electrode and a position where the processing object is disposed. In the discharge space as the first gas. A rare gas is introduced to generate plasma of the first gas, and a reactive thin film source gas is activated as the second gas by the plasma of the first gas and sprayed onto the object to be processed. This is a plasma processing method.
The invention according to claim 5 is the plasma processing method according to claim 4, wherein the object to be processed is arranged on a high frequency electrode, and a high frequency voltage is applied to the high frequency electrode.
[0016]
The present invention is configured as described above, and uses a low-reactivity gas such as a rare gas as the first gas, and a reactive gas such as oxygen or nitrogen as the second gas, or a thin film such as silane. The source gas is used to generate the first gas plasma, the second gas is activated by the first gas plasma, and the surface of the object to be processed is oxidized, nitrided, etched, or formed into a thin film, etc. The plasma treatment can be performed.
[0017]
Since the second gas is not introduced into the discharge space but released toward the object to be processed, a chemical reaction proceeds on or near the surface of the object to be processed, and an efficient plasma treatment is performed. I can do it.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
Referring to FIG. 1, reference numeral 3 is a plasma plasma processing apparatus according to a first example of the present invention, and has a vacuum chamber 51.
[0019]
The vacuum chamber 51 includes a container 31 and a high-frequency electrode 73.
The container 31 is horizontally disposed with the bottom surface of the container 31 facing downward, and a plate-like first discharge electrode 71 is attached to the opening.
[0020]
FIG. 3 is a plan view of the first discharge electrode 71 as viewed from the bottom surface side of the container 31. As shown in FIG. 3, a plurality of through holes 77 are formed in the first discharge electrode 71, and a rod-like second discharge electrode 72 is vertically inserted into each through hole 77. And four through holes in FIG. 1, reference numeral 77 _{1-77 4,} they are inserted into the through holes 77 ₁ to 77 ₄ four second discharge electrodes 72 ₁ to 72 ₄ are shown.
[0021]
FIG. 5 is an enlarged view of the vicinity of one second discharge electrode 72.
The lower end of the plurality of second discharge electrodes 72 ₁ to 72 ₄ is located above each lower end portion of the through hole 77 _{1-77 4,} i.e., the second discharge electrodes 72 ₁ to 72 ₄ the lower end of is located in the through-holes 77 ₁ to 77 _4.
[0022]
Each second discharge electrodes 72 ₁ to 72 ₄ of the top is protrudes above the first discharge electrode 71, the upper end portion thereof, the through-holes 77 ₁ to 77 flange-like diameter larger than ₄ Molded. Code 78 _{1-78 4} shows the flange portion thereof. The flange portions 78 _{1 to} 78 ₄ are attached to the upper surface of the first discharge electrode 71 in a state of being electrically insulated by an insulator.
[0023]
The outside of the container 31, first, second high-frequency power supply 14, 15 are arranged, each of the second discharge electrodes 72 ₁ to 72 ₄ of the connection to the first high frequency power supply 14 via a matching box 12 Has been.
[0024]
The high frequency electrode 73 has a plate shape and is attached to the bottom wall of the container 31 via an insulator. The high frequency electrode 73 is insulated from the container 31 by the insulator, and is connected to the second high frequency power supply 15 via the matching box 13.
[0025]
The container 31 and the first discharge electrode 71 are electrically connected, and the first and second discharge electrodes 71 and the first discharge electrode 71 are placed at a desired potential (here, ground potential). When the high frequency power supplies 14 and 15 are activated, a high frequency voltage can be independently applied to the first discharge electrode 71 and the high frequency electrode 73.
[0026]
Between the container 31 and the first discharge electrode 71, between the high-frequency electrode 73 and the container 31, and the like are hermetically sealed by an O-ring or an insulator, and the container 31 and the first and second discharge electrodes 71 and 72 are sealed. The internal space of the vacuum chamber 51 surrounded by the high-frequency electrode 73 is shielded from the external atmosphere. Therefore, when the evacuation system 35 connected to the container 31 is started, the inside of the vacuum chamber 51 can be made into a vacuum atmosphere.
[0027]
Reference numeral 8 denotes a plate-like substrate, which is an object to be processed by the plasma processing apparatus 3. While maintaining the vacuum atmosphere inside the container 31, the processing object 8 is placed on the surface of the high-frequency electrode 73 facing the first discharge electrode 71, the surface of the processing object 8 is pressed by the clamp 64, and the back surface is The high frequency electrode 73 is brought into close contact with the surface.
[0028]
On the inner peripheral surface of the through holes 77 ₁ to 77 _4, one or more first inlets 61 _{1-61 4} are provided respectively, also, a high-frequency electrode 73 of the first discharge electrode 71 A plurality (three in this case) of second inlets 62 _{1 to} 62 ₃ are provided on the opposing surfaces. Reference numeral 62 in FIG. 3 also indicates a second introduction port. Here, one or two or more are arranged at least between the through holes 77.
[0029]
A first inlet port 61 _{1-61 4,} the second inlet port 62 _{1-62 3} is connected to a different gas cylinder, and is configured to introduce a different gas.
[0030]
After the inside of the vacuum chamber 51 becomes a vacuum atmosphere of a predetermined pressure, the first discharge electrode 71 and the second discharge electrode 72 ₁ between 72 ₄ from the first inlet port 61 _{1-61 4} first introducing a gas, first, when a high frequency voltage is applied between the second discharge electrode 71, 72 ₁ to 72 _4, a inside of each through-hole 77 _{1-77 4,} first, second discharge space portion where the electrode 71 ₁ to 72 ₄ are opposed becomes the discharge space, a discharge occurs in the portion.
[0031]
A magnet 17 is embedded in the first discharge electrode 71. The magnet 17 is disposed so as to surround the discharge space, the trajectory of electrons emitted from the first or second discharge electrodes 71, 72 ₁ to 72 ₄ when the discharge is bent by the magnet 17, the Colliding with one gas molecule, a plasma of the first gas is generated in the discharge space. Since the first gas is for plasma generation and desirably has no reactivity, a rare gas such as argon gas is suitable.
[0032]
The inner peripheral surfaces of the through holes 77 _{1 to} 77 ₄ are perpendicular to the processing object 8, and the openings at the lower ends of the through holes 77 _{1 to} 77 ₄ face the processing object 8. It exists in the position (here, the position vertically above the processing object 8).
[0033]
The first gas ions and radicals are generated from the plasma in the discharge space, and the openings of the through holes 77 _{1 to} 77 ₄ serve as discharge ports, and the first gas ions and radicals are discharged toward the internal space of the container 31. Is done.
[0034]
At this time, a second gas, which is a raw material gas for the thin film, is introduced from the second gas introduction port 62, and the second gas undergoes a chemical reaction (second gas) by ions or radicals of the first gas. Decomposition reaction, polymerization reaction, etc.), and a thin film is formed on the surface of the processing object 8. Since the second gas is introduced from the second inlets 62 _{1 to} 62 ₃ and sprayed onto the processing object 8, the chemical reaction efficiently proceeds on the surface of the processing object 8 and in the vicinity of the surface.
[0035]
The cooling medium circulation paths 18 and 19 are provided inside the second discharge electrode 72 and the high-frequency electrode 73, and the second discharge electrode 72 and the high-frequency electrode 73 do not reach a high temperature during the film formation process. Has been.
[0036]
A cooling gas discharge path 10 is provided inside the high-frequency electrode 73 so that the cooling gas is supplied between the high-frequency electrode 73 and the processing object 8 to maintain the processing object 8 at a constant temperature. It is configured.
[0037]
The second introduction ports 62 _{1 to} 62 ₃ are provided in the first discharge electrode 71, but can be provided in other portions.
[0038]
Further, at a position between the first and second discharge electrodes 71, 72 ₁ to 72 ₄ and the high-frequency electrode 73 can be provided with a stabilizing electrode reticulated.
[0039]
Reference numeral 4 in FIG. 2 shows the plasma processing apparatus of the second example of the present invention having the stabilizing electrode 5. The same members as those in the plasma processing apparatus 3 in FIG. Omitted.
[0040]
This stabilization electrode 5 is arranged between the first and second discharge electrodes 71, 72 ₁ to 72 ₄ and the high-frequency electrode 73, the vicinity of the first and second discharge electrodes 71, 72 ₁ to 72 ₄ Placed in position.
[0041]
Stabilizing electrode 5 is electrically connected to the first discharge electrode 71, whereby the high-frequency voltage applied to the second discharge electrode 72 _{1-72 4} so as not to interfere.
[0042]
Reference numerals 63 _{1 to} 63 ₅ denote second introduction ports of the plasma processing apparatus 4. The second introduction ports 63 _{1 to} 63 ₅ are located between the stabilization electrode 5 and the high-frequency electrode 73. The second gas can be released toward the processing object 8 without being affected by the stabilization electrode 5.
[0043]
When the plasma of the first gas generated in the discharge space reaches the surface of the object 8 to be processed through the mesh portion of the stabilizing electrode 5, the surface and its surface, as in the case of the plasma processing apparatus 3 of FIG. In the vicinity, the chemical reaction of the second gas proceeds.
[0044]
In the plasma processing apparatuses 3 and 4 of the above-described embodiments, the same amount of electric power is applied to the plurality of second discharge electrodes 72, but the one positioned near the center of the processing object 8 and the vicinity of the outer periphery It is possible to make the in-plane distribution of the processing of the processing object 8 uniform. For example, in the case of a film forming process or an etching process, if the power near the center is reduced, the in-plane distribution becomes uniform.
[0045]
Further, in the plasma processing apparatuses 3 and 4 of the above embodiments, the high-frequency electrode 73 on which the object to be processed is arranged vertically downward, and the first and second discharge electrodes 71 and 72 are arranged vertically upward. The high frequency electrode 73 may be disposed vertically upward, and the first and second discharge electrodes 71 and 72 may be disposed vertically downward. In this case, it is necessary to prevent the processing object 8 from falling.
[0046]
In FIG. 3, the plurality of through-holes 77 and the second discharge electrodes 72 inserted therethrough are arranged in a matrix, but they may be arranged in a staggered manner as shown in FIG.
[0047]
【Example】
In the plasma processing apparatus 4 of the second example, an amorphous silicon film was formed on the surface of a 1300 mm × 1150 mm × 0.7 mm glass substrate using argon gas as the first gas and SiH ₄ gas as the second gas. The second gas was introduced between the stabilization electrode 5 and the processing object 8. The amount of the first and second gas introduced is 50 sccm.
[0048]
The first discharge electrode 71 was grounded, and a high frequency voltage of 80 MHz to 150 MHz was applied to each second discharge electrode 72 at a power density of 0.5 W / cm ² . The high frequency electrode 73 was connected to the ground potential.
[0049]
The pressure during film formation was maintained at 1 mTorr, and the temperature of the processing object 8 was maintained at 100 ° C.
[0050]
By discharging for 1 minute, a 3800 Å hydrogenated amorphous silicon film was obtained. The in-plane film thickness distribution was ± 3%.
[0051]
【Example】
In the plasma processing apparatus 3 of the first example, argon gas was used as the first gas, and HI gas (hydrogen iodide gas) was used as the second gas. The plasma processing apparatus 3 was formed on the surface of a 1300 mm × 1150 mm × 0.7 mm glass substrate. The ITO (indium tin oxide) film was etched. The amount of the first and second gas introduced is 50 sccm.
[0052]
The first discharge electrode 71 was grounded, and a high frequency voltage of 80 MHz to 150 MHz was applied to each second discharge electrode 72 at a power density of 0.8 W / cm ² . A high frequency voltage of 13.56 MHz was also applied to the high frequency electrode 73 at a power density of 0.8 W / cm ² .
[0053]
The pressure during etching was maintained at 15 mTorr, and the temperature of the processing object 8 was maintained at 80 ° C. As a result, an etching rate of 4500 Å / min was obtained. The in-plane etching amount distribution was ± 5%.
[0054]
【Example】
An argon gas was used as the first gas, an oxygen gas was used as the second gas, and the silicon substrate surface was oxidized to form a SiO _x thin film. The introduction amount of the first gas is 50 sccm, and the introduction amount of the second gas is 100 sccm. The pressure during film formation was 1 × 10 ⁻⁴ Pa and the substrate temperature was 400 ° C. A 400 ＳｉＯ SiO _x thin film was formed.
[0055]
【Example】
In the plasma processing apparatus 3 of the first example, argon gas was used as the first gas and oxygen gas was used as the second gas, and the aluminum substrate surface was oxidized to form an AlO _x thin film. The introduction amount of the first gas is 50 sccm, and the introduction amount of the second gas is 100 sccm. The pressure during film formation was 1 × 10 ⁻⁴ Pa and the substrate temperature was 200 ° C. A 250 Ａｌ AlO _x thin film was formed.
[0056]
【Example】
In the plasma processing apparatus 3 of the first example, argon gas was used as the first gas and nitrogen gas was used as the second gas, and the silicon substrate surface was nitrided to form a SiN _x thin film. The introduction amount of the first gas is 50 sccm, and the introduction amount of the second gas is 100 sccm. The pressure during film formation was 1 × 10 ⁻⁴ Pa and the substrate temperature was 500 ° C. A 200 Ｓｉ SiN _x thin film was formed.
[0057]
【The invention's effect】
Even if the object to be processed has a large area, it is possible to perform uniform plasma processing by increasing the discharge space.
In the plasma treatment, since the reactive second gas is blown toward the surface of the object to be treated, the reaction proceeds on or near the surface of the substrate, and the plasma treatment can be speeded up.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a plasma plasma processing apparatus of a first example of the present invention. FIG. 2 is a diagram for explaining a plasma plasma processing apparatus of a second example of the present invention. Example of electrode arrangement (1)
[Fig. 4] Arrangement example of second discharge electrode (2)
FIG. 5 is an enlarged view of the second discharge electrode and its vicinity. FIG. 6 is a diagram for explaining a conventional plasma plasma processing apparatus.
3, 4... Plasma treatment apparatus 5... Stabilization electrode 51... Vacuum chamber 61 (61 _{1 to} 61 ₄ )... First introduction port 62 (62 _{1 to} 62 ₃ ), 63 _{1 to} 63 _5. Second introduction port 71... First discharge electrode 72 (72 _{1 to} 72 ₄ )... Second discharge electrode 73.

Claims (5)

A vacuum chamber;
First and second discharge electrodes arranged opposite to each other in the vacuum chamber to form a discharge space;
A first inlet for introducing a first gas into the discharge space;
The high-frequency voltage applied to the second discharge electrode releases the plasma of the first gas generated in the discharge space toward the position where the object to be processed is disposed in the vacuum chamber. A plasma processing apparatus having an outlet,
In a position different from the discharge space in the vacuum chamber and between the position where the object to be processed is disposed and the discharge port, the first gas plasma is allowed to pass through. A stabilizing electrode electrically connected to the first discharge electrode is provided;
A second inlet for introducing a second gas is disposed at a position between the stabilizing electrode and a position where the processing object is disposed ;
A rare gas is introduced as the first gas, and a reactive thin film source gas is introduced as the second gas,
The plasma processing apparatus configured to spray the second gas introduced from the second introduction port onto the object to be treated. The second discharge electrodes, the plasma processing apparatus according to claim 1, wherein enclosed by the first discharge electrodes. A high frequency electrode to which a high frequency voltage is applied is disposed in the vacuum chamber,
The plasma processing apparatus according to claim 1, wherein the processing object is disposed on the high-frequency electrode. A vacuum chamber;
First and second discharge electrodes arranged opposite to each other in the vacuum chamber to form a discharge space;
A first inlet for introducing a first gas into the discharge space;
A discharge port for discharging the plasma of the first gas generated in the discharge space toward the position where the object to be processed is disposed in the vacuum chamber;
In a position different from the discharge space in the vacuum chamber and between the position where the object to be processed is disposed and the discharge port, the first gas plasma is allowed to pass through. A stabilizing electrode electrically connected to the first discharge electrode is provided;
Using a plasma processing apparatus in which a second introduction port for introducing a second gas is arranged at a position between the stabilization electrode and a position where the processing object is arranged,
  A rare gas is introduced into the discharge space as the first gas to generate a plasma of the first gas, and a reactive thin film source gas is used as the second gas as a plasma of the first gas. A plasma processing method that is activated by and sprayed onto the object to be processed. The plasma processing method of Claim 4 which arrange | positions the said process target object on a high frequency electrode, and applies a high frequency voltage to the said high frequency electrode.

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