JP2002198356A - Plasma treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma treatment apparatus that can improve a uniformity of a thin film by etching a resist film uniformly or improve a uniformity of the other plasma treatments, when the thin film being a treated object is etched by using a predetermined pattern through the resist film or the other plasma treatment are applied. SOLUTION: The plasma treatment apparatus 10 of this invention comprises an upper and a lower electrodes 12, 13 arranged within a treatment room 11, a second high-frequency power supply 15 applying a high-frequency power to the upper electrode 13, and a quartziferous shield ring 21 covering the peripheral edge of the undersurface of the upper electrode 13, and the contact area of the shield ring 21 with a plasma is covered by a plasma-resistant film 21B made of yttrium oxide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus, and more particularly, to a plasma processing apparatus capable of performing plasma processing such as uniform etching on the entire surface of an object to be processed.

[0002]

2. Description of the Related Art A conventional plasma processing apparatus is, for example, shown in FIG.
As shown in FIG. 1, a lower electrode 1 arranged in a chamber (not shown) so as to be movable up and down in parallel with each other, and the lower electrode 1
An upper electrode 2 arranged in parallel with each other, and first and second high-frequency power sources 3 for applying high-frequency powers having different frequencies to both electrodes 1 and 2 via matching units 3A and 4A. The first and second high-frequency power supplies 3 and 4 apply high-frequency power to the upper and lower electrodes 1 and 2 to generate plasma, thereby oxidizing silicon on the surface of the wafer W to be processed. It is configured to etch the film. A focus ring 5 surrounding the wafer W is disposed on the outer peripheral edge of the upper surface of the lower electrode 1, and a shield ring 6 is provided on the outer peripheral edge of the upper electrode 2.
The plasma generated between them is focused on the wafer W.

Although not shown, the upper electrode 2 has an electrode material and a support for supporting the electrode material, and the electrode material is fastened to the support via screws made of stainless steel or the like. . The shield ring 6 is attached to the upper electrode 2 to protect such screws from plasma and to focus the plasma on the wafer W in cooperation with the focus ring 5. The shield ring 6 is formed of an insulating material such as quartz, for example, so that no contaminants are generated from the shield ring 6 during the etching process. In addition to quartz, for example, ethylene tetrafluoride resin or the like is used as the material of the shield ring 6 (Japanese Patent Laid-Open No. 1-18).
No. 9124).

[0004]

However, for example, in the case of a plasma processing apparatus in which a shield ring is formed of quartz, a fluorocarbon gas (C
_When the silicon oxide film of the wafer W is subjected to an etching process according to a predetermined pattern through the resist film by using ₍ xF _y ), the etching rate of the resist film at the outer peripheral edge of the wafer W is increased as shown in FIG. Increased from the inside thereof, and it was found that the etching rate of the resist film became non-uniform. At this time, as shown in FIG. 8, the interval between the upper and lower electrodes 1 and 2 was changed in three steps from 21 mm to 35 mm, and the etching rate of the resist film at each interval was measured. In portions, the etching rate sharply rises, and the etching rate of the resist film becomes non-uniform.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. When a thin film of an object to be processed is subjected to an etching process through a resist film in a predetermined pattern or another plasma process, a resist is formed. It is an object of the present invention to provide a plasma processing apparatus capable of improving the uniformity of etching of a thin film by uniformly etching a film and improving the uniformity of other plasma processing.

[0006]

Means for Solving the Problems The present inventors have proposed quartz (S)
As a result of various investigations regarding the cause of an increase in the etching rate of the outer peripheral edge of the resist film when the silicon oxide film is etched using a plasma processing apparatus having a shield ring made of iO ₂ ), the following was found. That is, the surface of the shield ring 6 is subjected to ion attack in the plasma during etching. At this time, since the shield ring 6 is formed of quartz, the following reaction occurs due to ion attack, and a reaction by-product such as oxygen is generated between the upper and lower electrodes 1 and ₂ from SiO ₂ . In particular, if there is a step between the inner peripheral end of the shield ring 6 and the electrode material as shown in FIG. 6, the step is likely to be sputtered, so that the amount of oxygen released from the shield ring 6 increases. It is estimated that the etching rate of the resist film at the outer peripheral edge of the wafer W is higher than that inside the wafer W due to the influence of oxygen, and the etching rate of the resist film becomes non-uniform. SiO ₂ + C _x F _y → SiF _{4 {} + CO _} + O _{2 }}

The present invention has been made based on the above findings. According to a first aspect of the present invention, there is provided a plasma processing apparatus comprising: first and second electrodes arranged in a processing vessel in parallel with each other; A high-frequency power supply for applying high-frequency power to the electrodes;
A shield ring made of an inorganic oxide that covers at least an outer peripheral edge of a lower surface of the first electrode; a high-frequency power is applied to the first electrode to generate plasma; and a processing object supported by the second electrode. A plasma processing apparatus for performing a plasma process on a shield ring, wherein a contact portion of the shield ring with plasma is covered with a plasma resistant film.

According to a second aspect of the present invention, there is provided a plasma processing apparatus comprising: a first electrode, a second electrode disposed in parallel with each other in a processing vessel; and a high frequency power for applying a high frequency power to at least the first electrode. A power supply and a shield ring made of an inorganic oxide covering at least the outer peripheral edge of the lower surface of the first electrode are provided, and high-frequency power is applied to the first electrode to generate plasma and supported by the second electrode. In a plasma processing apparatus for performing an etching process on a thin film in a predetermined pattern through a resist film on an object to be processed, a contact portion of the shield ring with plasma is covered with a plasma resistant film.

According to a third aspect of the present invention, there is provided a plasma processing apparatus according to the first or second aspect, wherein the plasma resistant film is made of a rare earth element oxide or a heat resistant resin. It is a feature.

[0010] A plasma processing apparatus according to a fourth aspect of the present invention is the plasma processing apparatus according to the third aspect, wherein the rare earth element is yttrium.

[0011] The plasma processing apparatus according to a fifth aspect of the present invention is the plasma processing apparatus according to the third aspect, wherein the heat-resistant resin is a polyimide resin.

According to a sixth aspect of the present invention, in the plasma processing apparatus according to any one of the second to fifth aspects, the thin film is a silicon oxide film. Things.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments shown in FIGS. As shown in FIG. 1, for example, a plasma processing apparatus 10 of the present embodiment includes a processing chamber 11 made of a conductive material such as aluminum,
A lower electrode 12 disposed on the bottom surface of the inside and on which a wafer W to be processed is mounted, and an upper electrode 13 disposed in parallel to the lower electrode 12 and serving also as a processing gas supply unit And A first high-frequency power supply 14 is connected to the lower electrode 12 via a matching unit 14A.
Is connected to a second high frequency power supply 15 having a frequency higher than that of the first high frequency power supply via a matching unit 15A. A gas supply source 16 is connected to the upper electrode 13 via a valve 16A and a mass flow controller 16B.
To the upper electrode 13 from the fluorocarbon gas (C _x F _y )
And other processing gases. An exhaust port 11A is formed on the bottom surface of the processing chamber 11, and the inside of the processing chamber 11 is exhausted through an exhaust device (not shown) connected to the exhaust port 11A to maintain a predetermined degree of vacuum with a processing gas.

Therefore, for example, the first high-frequency power supply 14 is kept in a state where a predetermined degree of vacuum is maintained in the processing chamber 11 with the processing gas.
From the second high-frequency power supply 15 to the upper electrode 13.
When a second high-frequency power of 0 MHz is applied, a plasma of a processing gas is generated between the lower electrode 12 and the upper electrode 13 by the action of the second high-frequency power, and the lower electrode 12 is self-generated by the action of the first high-frequency power. A bias potential is generated, and plasma processing such as reactive ion etching can be performed on the wafer W on the lower electrode 12.

A focus ring 17 surrounding the outer periphery of the wafer W is provided on the outer peripheral edge of the upper surface of the lower electrode 12.
Plasma is collected on the wafer W via the focus ring 17. On the upper surface of the lower electrode 12, an electrostatic chuck 18 connected to a high-voltage DC power supply 18A is provided.
The electrostatic chuck 18 electrostatically chucks the wafer W with a high-voltage DC voltage applied from a high-voltage DC power supply 18A. The lower electrode 12 has a built-in cooling mechanism 19 and a heating mechanism (not shown), and adjusts the temperature of the wafer W to a predetermined temperature via the cooling mechanism 19 and the heating mechanism. Further, the lower electrode 12
Inside, a gas passage 12A through which a heat transfer medium (for example, He gas) opens at a plurality of locations on the upper surface is formed,
Further, a hole 18B corresponding to the opening of the gas passage 12A is formed in the electrostatic chuck 18, and He gas is supplied to a narrow space between the wafer W and the electrostatic chuck 18 to thereby form the lower electrode 12B.
Heat transfer between the wafer and the wafer W. Also, the lower electrode 12
For example, an aluminum bellows 20 is interposed between the bottom surface of the processing chamber 11 and the bottom surface of the processing chamber 11, and the lower electrode 12 is moved up and down via an elevating mechanism (not shown). I can do it.

As shown in FIG. 2, the upper electrode 13 has, for example, a plate-like silicon electrode material 13A and a hollow aluminum support 13B for detachably supporting the electrode material 13A. ing. A thin portion 13C is formed over the entire outer periphery of the electrode material 13A.
A is fastened to the support 13B via the bolt 13D at the thin portion 13C. Bolt 13D is thin part 1
They are arranged at equal intervals in the circumferential direction of 3C. Further, a shield ring 21 is attached to the upper electrode 13. The shield ring 21 is formed of, for example, an inorganic oxide such as quartz or alumina (quartz is used in the present embodiment), and covers the outer peripheral surface of the upper electrode 13 and the thin portion 13C of the electrode material 13A as shown in FIG. The lower surface of the upper electrode 13 is flush with the electrode material 13A. Also, the upper electrode 1
In the lower surface of the third electrode material 13A and the lower surface of the support 13B, holes 13E that match each other are formed in a dispersed manner, and the processing gas received by the upper electrode 13 from the gas supply source 16 is evenly distributed in the entire processing chamber 11. Supply. In FIG. 1,
Reference numeral 22 denotes a high-pass filter for filtering a high-frequency current flowing from the second high-frequency power supply 15 into the lower electrode 12, and reference numeral 23 denotes a low-pass filter for filtering a high-frequency current flowing from the first high-frequency power supply 14 to the upper electrode 13.

The portion of the shield ring 21 covering the thin portion 13C of the electrode material 13A is formed by the flange portion 21.
A is formed. The lower surface of the flange portion 21A is covered with a plasma resistant film 21B so that the quartz shield ring 21 does not come into direct contact with the plasma. A plasma-resistant film is a film that has plasma resistance and does not generate oxygen or pollutants even when subjected to ion attack. The plasma resistant film 21B is formed of a rare earth element oxide such as yttrium oxide (Y ₂ O ₃ ) or a heat resistant resin such as a polyimide resin. The yttrium oxide film can be formed to an appropriate thickness by spraying yttrium oxide with atmospheric plasma,
Although the film thickness is not particularly limited, for example, 100 to 500
A μm thickness is preferred. As the polyimide resin, for example, an adhesive tape made of a polyimide resin is preferably used.
Although yttrium oxide contains oxygen atoms in the crystal structure, similarly to quartz, the bond energy between yttrium atoms and oxygen atoms is high and stable. Are hardly cleaved and dissociation of oxygen atoms can be remarkably suppressed. The polyimide resin is also thermally stable, and can suppress dissociation of oxygen atoms due to ion attack.

Therefore, the shield ring 2 of the upper electrode 13
Since the generation of oxygen from the shield ring 21 can be remarkably suppressed even if the wafer 1 receives an ion attack, there is a possibility that the etching rate of the resist film by the oxygen plasma on the outer peripheral portion of the wafer W is increased as in the related art. In addition, the etching rate of the resist film over the entire surface of the wafer W can be made uniform. That is, it can be seen that the plasma at the outer peripheral portion of the wafer W is oxygen-rich due to the increase in the etching rate of the resist film at the outer peripheral portion of the wafer W.
For example, when etching the silicon oxide film by using a fluorocarbon gas (C x _{F y),} the shield ring 2
1 is covered with the plasma resistant film 21B,
The plasma at the outer peripheral portion of the wafer W does not become oxygen-rich, and the etching rate of the resist film can be made uniform. Furthermore, if the plasma at the outer peripheral portion of the wafer W is oxygen-rich, the etching rate of the resist film at the outer peripheral portion of the wafer W increases, and the side wall protection in the opening of the silicon oxide film dug at this portion is performed. CF polymer in film or C in plasma in opening
F ions and the like react with oxygen to generate CO and CO ₂ and become rich in fluorine, so that the etching rate of the silicon oxide film is higher than that of other parts of the wafer W and the uniformity of the etching rate on the entire surface of the wafer W is poor. And the shape is deteriorated due to the expansion of the side wall. However, in the present embodiment, the etching rate of the resist film over the entire surface of the wafer W can be made uniform and the etching rate of the silicon oxide film can be made uniform, without becoming oxygen-rich at the outer peripheral portion of the wafer W. As a result, a vertical sidewall shape can be formed.

When the silicon oxide film is etched, for example, there are modes shown in FIGS. The wafer W shown in FIG. 1A has a silicon oxide film layer SO and a resist film layer R on a silicon S. When etching the silicon oxide film SO of the wafer W, the silicon oxide film layer SO is etched according to a predetermined pattern of the resist film layer R. At this time, in the case of the present embodiment, since the oxygen is hardly generated from the shield ring 21, the etching rate of the resist film R at the outer peripheral portion of the wafer W does not increase, and the silicon oxide film is uniformly etched. And a vertical sidewall shape can be formed. In particular, when the silicon oxide film layer R is BPS
In the case of G, bowing is likely to occur due to the influence of oxygen, but in the present embodiment, bowing can be prevented. The wafer W shown in FIG. 2B is a silicon oxide film SO
Having a silicon nitride film layer SN and a resist film layer R thereon;
The wafer W shown in FIG. 3C has a polysilicon film layer pS and a resist film layer R on the silicon oxide film SO. Also in these cases, the etching rate over the entire resist film layer R is uniform as in the case of the wafer W shown in FIG.
The silicon oxide film layer SO can be uniformly etched on the entire surface of the wafer W. The wafer W shown in (d) of the same figure has an alloy film layer A of aluminum, silicon, and copper on silicon.
L and a resist film layer R. In this case, oxidation of the alloy film layer AL at the outer peripheral portion of the wafer W can be suppressed. The wafer W shown in FIG. 3E has a silicon oxide film layer SO and a tungsten film layer MW on silicon. When the tungsten film layer MW of the wafer W is etched back, the oxidation of tungsten at the outer peripheral portion of the wafer W can be suppressed. In addition, the wafer W shown in FIG. 3F has a silicon nitride film S on silicon.
It has a polysilicon film layer pS covered with N, a silicon oxide film SO, and a resist film layer R. Even when performing self-align contact (SAC) etching on the wafer W, the influence of oxygen is suppressed, the etching rate is uniform over the entire resist film layer R, and uniform SAC etching can be performed over the entire wafer W.

As described above, according to the present embodiment,
Since the plasma-resistant film 21B covers the contact portion of the shield ring 21 with the plasma, when performing plasma processing such as etching, even if the shield ring 21 receives an ion attack, oxygen is generated from the shield ring 21 to generate a wafer. W
There is no possibility that the plasma at the outer peripheral portion becomes oxygen-rich, and the etching rate of the resist film over the entire surface of the wafer W can be made uniform without increasing the etching rate of the resist film at the outer peripheral portion of the wafer W. The etching rate and etching shape of the W silicon oxide film can be made uniform.

FIG. 3 is a sectional view showing an upper electrode used in another embodiment of the present invention. The upper electrode 113 shown in FIG.
13B and the shield ring 121, and the electrode material 113
It is formed in the same manner as that shown in FIG. 2 except that the shape of A is different. The entire electrode material 113A is formed to have the same thickness. The bolt 113D that connects the electrode material 113A and the support 113B is covered by the engaging portion 121A of the shield ring 121. This engaging portion 121A is different from that shown in FIG. 2 in that there is a step between the engaging portion 121A and the lower surface of the electrode material 131A. The lower surface and the step portion of the engaging portion 121A, that is, the contact portion with the plasma is covered with the plasma resistant film 121A. Also in the present embodiment, it is possible to suppress the generation of oxygen from the shield ring 121 during the plasma processing, and it is possible to expect the same operation and effect as in the above embodiment.

Next, a specific embodiment will be described. Embodiment 1 FIG. In this example, a sprayed film of yttrium oxide was used as the plasma resistant film 21B, and etching was performed under the following process conditions. At this time, the etching rate of the resist film was measured, and the respective results are shown in FIG. However,
The distance between the lower electrode 12 and the upper electrode 13 is 21 mm, 25 m
m, 35 mm.

[Process conditions] Wafer: 200 mm Resist film: Kr-F resist film Film to be etched: silicon oxide film Processing contents: contact Upper electrode: power supply frequency = 60 MHz, power supply power = 150
0W Lower electrode: power supply high frequency = 2 MHz, power supply power = 160
0 W Processing pressure: 20 mTorr Process gas: C ₄ F ₈ = 8 sccm, Ar = 300 sccm,
O ₂ = 8 sccm

According to the results shown in FIG. 5, the etching rate at the outer peripheral portion of the wafer W is lower than that of the conventional plasma processing apparatus shown in FIG. It can be seen that the etching rate is uniform. As is clear from this, by covering the shield ring 21 with the plasma resistant film 21B, generation of oxygen at the outer peripheral edge of the wafer W can be significantly suppressed, and adverse effects on etching due to oxygen are significantly suppressed. I found that I could do that.

Embodiment 2 FIG. In this embodiment, the plasma resistant film 2
Etching was performed under the same conditions as in Example 1 using a polyimide film (specifically, Kapton tape) as 1B, and the etching rate of the resist film at this time was measured.
FIG. 6 shows the result. Also in this embodiment, Embodiment 1
The same result was obtained.

In the above embodiment, the case where the sprayed yttrium oxide film and the Kapton tape are used as the plasma resistant film has been described. If it is, there is no particular limitation. In the above-described embodiment, the description has been given by taking the quartz shield ring as an example. However, the present invention is not particularly limited as long as the shield ring is made of an inorganic oxide that releases oxygen when exposed to plasma. Not something. Further, in the present invention, when the protective cover and the focus ring attached to the lower electrode are made of an inorganic oxide such as quartz, the same effect is expected by coating these members with a plasma resistant film. can do. Further, in the above embodiment, the etching process is described as an example, but the present invention can be applied to a plasma process such as a CVD process.

[0027]

According to the first and third to fifth aspects of the present invention, it is possible to provide a plasma processing apparatus capable of improving the uniformity of the plasma processing.

Further, according to the present invention, when the thin film of the object to be processed is etched in a predetermined pattern through the resist film, the resist film is uniformly formed. It is possible to provide a plasma processing apparatus which can perform an etching process and thereby improve the uniformity of etching of a thin film.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of a plasma processing apparatus of the present invention.

FIG. 2 is an enlarged sectional view showing the shield ring shown in FIG. 1;

FIG. 3 is a cross-sectional view corresponding to FIG. 2, showing a shield ring used in a plasma processing apparatus according to another embodiment of the present invention.

4 (a) to 4 (f) are schematic diagrams showing a layer configuration of a wafer to be etched using the plasma processing apparatus shown in FIG.

5 is a graph showing an etching rate of a resist film in a case where a shield ring of an upper electrode shown in FIG. 2 is covered with yttrium oxide and a silicon oxide film is etched by changing a distance between upper and lower electrodes.

6 is a graph corresponding to FIG. 4 showing the etching rate of a resist film when the shield ring of the upper electrode shown in FIG. 2 is covered with a polyimide film and the silicon oxide film is etched by changing the distance between the upper and lower electrodes. It is.

FIG. 7 is a configuration diagram illustrating an example of a conventional plasma processing apparatus.

8 is a graph corresponding to FIG. 5 showing an etching rate of a resist film when a silicon oxide film is etched using the plasma processing apparatus shown in FIG. 7 while changing the distance between upper and lower electrodes.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Plasma processing apparatus 11 Processing chamber 12 Lower electrode (2nd electrode) 13 Upper electrode (1st electrode) 14 1st high frequency power supply 15 2nd high frequency power supply (high frequency power supply) 21 Shield ring 21B Plasma resistant film W Wafer (Object to be processed)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4K030 FA03 KA47 5F004 AA01 BA04 BA09 BA20 BB11 BB22 BB23 BB25 BB26 BB28 BB29 BB32 DA22 DB03 DB06 5F045 AA08 EB03 EH06

Claims (6)

[Claims] A first electrode, a second electrode, and a high-frequency power supply that apply high-frequency power to at least the first electrode; and a high-frequency power supply that applies high-frequency power to at least the first electrode. A shield ring made of an inorganic oxide to be coated, wherein a high-frequency power is applied to the first electrode to generate plasma, and the plasma processing apparatus performs a plasma process on the object supported by the second electrode. A plasma processing apparatus characterized in that a portion of a shield ring contacting plasma is coated with a plasma resistant film. 2. A first and a second electrode arranged in parallel in a processing container, a high-frequency power supply for applying a high-frequency power to at least the first electrode, and at least an outer peripheral portion of a lower surface of the first electrode. A shield ring made of an inorganic oxide to be coated, applying a high-frequency power to the first electrode to generate plasma, and forming a predetermined pattern on the thin film via a resist film on the object supported by the second electrode 2. A plasma processing apparatus according to claim 1, wherein a contact portion of said shield ring with plasma is covered with a plasma resistant film. 3. The plasma-resistant film is made of a rare earth oxide or a heat-resistant resin.
Alternatively, the plasma processing apparatus according to claim 2. 4. The plasma processing apparatus according to claim 3, wherein said rare earth element is yttrium. 5. The plasma processing apparatus according to claim 3, wherein the heat-resistant resin is a polyimide resin. 6. The plasma processing apparatus according to claim 2, wherein the thin film is a silicon oxide film.