JP2003318163A - Device and method for plasma treatment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma treatment device that is contrived to efficiently and uniformly etch an object to be treated without giving any damage to the object. <P>SOLUTION: This plasma treatment device is provided with a placing electrode 12 which is disposed in a chamber 11 and from which a placing section 14 for placing an object 15 to be treated is protruded, a counter electrode 13 disposed in the chamber 11 to face the electrode 12, and a high-frequency power source 17 which generates plasma by exciting an etching gas supplied into the chamber 11 by supplying energy across the electrodes 12 and 13. This device is also provided with a plasma control member 25 having an opening 26 which has a slightly larger diameter than the placing section 14 has and in which the placing section 14 is housed so that a passage 27 may be formed between the inner peripheral surface of the opening 26 and the outer peripheral surface of the section 14, provided between the electrodes 12 and 13, and composed of an electrical insulating material that collects the plasma generated by the high-frequency power source in the opening 26 and relieves, the plasma deviated from the peripheral edge section of the object 15 from the passage 27. <P>COPYRIGHT: (C)2004,JPO

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 a plasma processing method for etching an object to be processed with plasma generated by exciting an etching gas.

[0002]

2. Description of the Related Art For example, in a manufacturing process of a semiconductor device, an unnecessary thin film formed on a semiconductor wafer is removed by etching. A plasma processing apparatus is used to remove unnecessary thin films by etching.

As is well known, the plasma processing apparatus has a chamber in which a pair of electrodes are arranged so as to face each other. High frequency power is applied to the pair of electrodes. As a result, the etching gas supplied into the chamber is excited and plasma is generated.

The object to be processed is placed on one of the electrodes. This one electrode has a negative potential. Therefore, the positive ions contained in the plasma generated in the chamber are accelerated by the negative potential of one of the electrodes and collide with the object to be processed, so that an unnecessary thin film provided on the object to be processed can be removed. .

When etching an object to be processed by using such a plasma processing apparatus, it is required to improve the processing capacity. In order to improve the processing capacity, plasma generated in the chamber is not dispersed but concentrated on the object to be processed.

A plasma processing apparatus disclosed in Japanese Patent Publication No. 5-7861 is known as a prior art. In a conventional plasma processing apparatus, a pair of electrodes are arranged to face each other in a chamber, and a peripheral portion of one electrode on which a workpiece is placed is surrounded by a closely-spaced structure made of a dielectric material. With this narrowly spaced structure, the spacing between the electrodes is set narrower than the spacing between the pair of electrodes.

High frequency power is supplied to the pair of electrodes by a high frequency power supply. An etching gas is supplied into the chamber by a gas pipe 7.

When the pressure in the chamber is reduced and the etching gas is supplied to the chamber and high frequency power is applied to the pair of electrodes, the etching gas is excited and plasma is generated. Then, the plasma, that is, the positive ions contained in the plasma are accelerated toward the electrode, so that the workpiece mounted on the electrode is etched.

Since the plasma is concentrated on the electrodes inside the narrow-spacing structure by surrounding the peripheral portion of the electrode with the narrow-spacing structure made of a dielectric material, the efficiency of the etching process can be improved. Is.

[0010]

When the peripheral portion of the electrode on which the work piece is placed is surrounded by the narrowly-spaced structure, the electric discharge can be concentrated inside and the etching efficiency of the work piece can be improved. Although it is possible, the distribution density of plasma inside the closely-spaced structure tends to be higher in the peripheral portion of the electrode than in the other portion. It is considered that when the peripheral portion of the electrode is surrounded by the narrowly-spaced structure, it becomes difficult for the plasma to escape from the peripheral portion of the electrode to the outside, and the plasma is more easily concentrated than other portions.

As a result, the number of positive ions that collide with the peripheral portion of the workpiece located around the electrode is large, so that the workpiece cannot be uniformly etched, or the peripheral edge of the workpiece is not etched. There is a risk that the parts will be easily damaged.

According to the present invention, the plasma is concentrated on the object to be processed so as to improve the processing efficiency, and the plasma is not concentrated on the peripheral portion of the object to be treated more than at other places. It is an object of the present invention to provide a plasma processing apparatus and a plasma processing method capable of performing etching processing uniformly and without damaging the peripheral portion.

[0013]

To solve the above problems, a plasma processing apparatus of the present invention is a plasma processing apparatus for exciting an etching gas to process an object to be processed, wherein a chamber into which the etching gas is introduced. A mounting electrode provided with a mounting portion that is disposed in the chamber and on which the object to be processed is mounted, a counter electrode disposed to face the mounting electrode in the chamber, and Excitation means for supplying energy between the pair of electrodes to excite the etching gas supplied in the chamber to generate plasma.
An opening having a diameter slightly larger than that of the placement portion is provided, and the placement portion is accommodated in this opening to form a passage between the inner peripheral surface of the opening and the outer circumferential surface of the placement portion. And a plasma control member provided between the pair of electrodes, which collects the plasma generated by the excitation means in the opening and discharges the plasma deviated from the peripheral portion of the object to be processed from the passage, and a plasma control member. Is provided.

A plasma processing method according to the present invention is a plasma processing method for exciting an etching gas to process an object to be processed provided in a chamber, and introducing the etching gas into the chamber, A step of generating plasma in the chamber by being excited, and a step of collecting plasma generated in the chamber to the object to be processed and escaping plasma deviating from the peripheral portion of the object to be processed without acting on the object to be processed. And is provided.

According to the present invention, the plasma can be concentrated on the object to be processed to improve the processing efficiency, and the plasma can be prevented from acting more strongly on the peripheral portion of the object than the other portions. Therefore, it becomes possible to uniformly etch the object to be processed and without damaging the peripheral portion.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show a first embodiment of the present invention. The plasma processing apparatus shown in FIG. 1 includes a chamber 11. A mounting electrode 12 is provided on the inner bottom of the chamber 1.
Is provided. A counter electrode 13 is arranged above the mounting electrode 12 so as to face the mounting electrode 12.

In the above described mounting electrode 12, the mounting portion 1 is provided in the central portion.
4 is formed in a protruding manner, and the peripheral portion of the mounting portion 14 is mounted on the mounting portion 1.
It is formed in a thin portion 14a which is thinner than No. 4. The above-mentioned placing portion 14 has, for example, a disc shape.

An object to be processed 15 such as a semiconductor wafer is placed on the upper surface of the placing section 14. The planar shape of the object to be processed 15 is set to be equal to or smaller than the planar shape of the placing portion 14 described above, and slightly smaller in this embodiment.

A high frequency power source 17 as an excitation means is connected to the above-mentioned mounting electrode 12 via a capacitor 16, and the counter electrode 13 is grounded. By applying high-frequency power to the placement electrode 12 and the counter electrode 13, the discharge can be generated in the space portion between these electrodes, that is, the discharge space portion 18.

An etching gas is supplied to the discharge space 18 between the placement electrode 12 and the counter electrode 13 through a gas supply pipe 19. The counter electrode 13 is formed in a hollow shape. An etching gas is supplied from the gas supply pipe 19 into the counter electrode 13. The etching gas is allowed to flow out from the outflow portion (not shown) formed in the counter electrode 13 into the discharge space 18 substantially uniformly.

The etching gas supplied to the discharge space 18 is excited by the discharge generated between the pair of electrodes 12, 13. As a result, plasma is generated in the discharge space portion 18. A vacuum pump 21 as a pressure reducing means is connected to the chamber 11 via an exhaust pipe 22 so that the inside of the chamber 11 can be depressurized.

A plasma control member 25 formed of an electrically insulating material (dielectric) such as synthetic resin or quartz is provided between the above-mentioned mounting electrode 12 and the counter electrode 13.
The plasma control member 25 has a planar shape having substantially the same size as the planar shape of the mounting electrode 12 described above, and has a ring shape with an opening 26 formed in the central portion.

The inside diameter of the opening 26 is slightly larger than the outside diameter of the placing portion 14 of the placing electrode 12, and the placing portion 14 is accommodated in the opening 26. Has been done. As a result, the first passage 27 is formed between the inner peripheral surface of the opening 26 and the outer peripheral surface of the placing portion 14.
Is formed.

The plasma control member 25 is the mounting electrode 12
And the counter electrode 13 in a non-contact state. As a result, a second passage 28 communicating with the lower end of the first passage 27 is formed between the lower surface of the plasma control member 25 and the upper surface of the thin portion 14a of the mounting electrode 12.

The lower surface of the plasma control member 25 may be brought into contact with the upper surface of the thin portion 14a of the mounting electrode 12, in which case the lower surface of the plasma control member 25 or the thin portion 1
A radial groove may be formed on the upper surface of 4a, and this groove may be used as a second passage whose one end communicates with the first passage 27.

Next, a case where the object 15 to be processed is etched by the plasma processing apparatus having the above structure will be described.

When the chamber 11 is depressurized to a predetermined pressure, high frequency power is applied to the pair of electrodes 12 and 13, and an etching gas is supplied from the gas supply pipe 19 to the discharge space 18 in the chamber 11. As a result, the etching gas is excited by the discharge generated between the pair of electrodes 12 and 13, so that plasma is generated in the discharge space portion 18.

Since the plasma generated in the discharge space 18 is accelerated toward the mounting electrode 12, the object to be processed is etched by the ions contained in the plasma.

By providing the plasma control member 25 between the mounting electrode 12 and the counter electrode 13, the plasma generated in the discharge space 18 and directed to the mounting electrode 12 is formed in the plasma control member 25. It passes through the opening 26. If the mass of the plasma generated in the discharge space 18 is the same as the mass of the plasma passing through the opening 26, the opening is larger than the area of the counter electrode 13, which is the cross-sectional area of the discharge space 18. Since the area of 26 is small, the velocity of plasma passing through the opening 26 is faster than the velocity of plasma in the discharge space 18.

Therefore, the velocity of the plasma that collides with the object to be processed 15 placed on the placing portion 14 of the placing electrode 12 located in the opening 26 is accelerated, so that the etching rate is improved. The processing efficiency can be improved.

For example, the plasma density is ρ (kg / m
³ ), the absolute pressure in the chamber 11 is p (kPa), the gas constant is R (J / kg · K), and the absolute temperature is T (K), then ρ = RT according to Boylechar's law. The flow velocity of plasma in the discharge space 18 is v ₁ , the flow velocity of plasma in the opening 26 of the plasma control member 25 is v ₂ , and the area of the counter electrode 13 which is the cross-sectional area of the discharge space 18 is a.
₁ and the area of the opening 26 is a ₂ , the mass m ₁ of plasma in the discharge space 18 is m ₁ = ρ · v ₁ · a ₁ , and the mass m ₂ of plasma in the opening 26 is m ₂ = ρ · v ₂ · a ₂ . Therefore, considering that the plasma masses m ₁ and m ₂ are the same, it can be explained that the plasma flow velocity in the opening 26 having a smaller area is faster than the plasma flow velocity in the discharge space 18.

A first passage 27 is formed between the inner peripheral surface of the plasma control member 25 and the outer peripheral surface of the mounting portion 14 on which the workpiece 15 is mounted. The lower end is the lower surface of the plasma control member 25 and the thin portion 1 of the mounting electrode 12.
It communicates with the second passage 28 formed between the upper surface of 4a.

Therefore, the plasma generated in the discharge space 18 increases in speed and the opening 26 of the plasma control member 25 increases.
When acting on the upper surface of the object 15 to be processed through
Of the first passage 27, as shown by an arrow X in FIG. 2, does not act on the object to be processed 15 without being affected by the plasma deviated from the upper surface of the opening 26, that is, the plasma flowing near the inner peripheral surface of the opening 26.
And escapes radially outward of the mounting electrode 12 through the second passage 28.

Assuming that the inner peripheral surface of the opening 26 is in close contact with the outer peripheral surface of the mounting portion 14 and the first passage 27 is not formed, the plasma flowing near the inner peripheral surface of the opening 26 is The reflected light is reflected on the inner peripheral surface and acts on the peripheral portion of the object 15 to be processed placed on the mounting portion 14. As a result, the peripheral edge portion of the object to be processed 15 is subjected to the action of plasma more than other portions, so that the entire surface may not be uniformly etched, or the peripheral edge portion may be damaged.

However, the plasma flowing in the peripheral portion of the opening 26 escapes through the first and second passages 27 and 28 as indicated by the arrow X and hardly acts on the object to be processed 15. Therefore, the entire upper surface of the processed portion 15 is etched almost uniformly, and
There is no damage to the periphery.

That is, even if the plasma control member 25 is provided between the mounting electrode 12 and the counter electrode 13, the etching rate can be increased without impairing the uniformity of the etching process on the object 15.

FIG. 3 shows a plasma processing apparatus according to the second embodiment of the present invention. The second embodiment is a modification of the counter electrode 13A, and the protrusion 31 is integrally formed on the counter electrode 13A. The protruding portion 31 is set to have substantially the same outer dimensions as the mounting portion 14 of the mounting electrode 12 described above. The protruding portion 31 has, for example, a disc shape.

The plasma control member 25A provided between the mounting electrode 12 and the counter electrode 13A is formed thicker than that in the first embodiment, and the opening 26 has the mounting portion 14 and the counter electrode 13A. The protruding portions 31 are accommodated so as to be spaced apart from each other and face each other. Outer peripheral surface of protrusion 31 and opening 2
A third passage 32 is formed between the inner peripheral surface of 6 and the inner peripheral surface of 6.

According to the plasma processing apparatus having such a configuration, it is possible not only to reduce the facing distance between the placing portion 14 of the placing electrode 12 and the projecting portion 31 of the counter electrode 13, but also to place the placing portion. Since the discharge generated between the electrode 12 and the counter electrode 13 can be concentrated between the mounting portion 14 and the protruding portion 31, the intensity of the discharge generated between them can be increased,
The excitation efficiency of the etching gas can be improved.

FIG. 4 shows a plasma processing apparatus according to the third embodiment of the present invention. Similar to the second embodiment, this embodiment is a modified example of the counter electrode 13B, and the outer dimension of the counter electrode 13B is substantially the same as the inner diameter dimension of the opening 26 formed in the plasma control member 25. Is set to

According to this structure, the discharge can be concentrated between the mounting portion 14 of the mounting electrode 12 and the counter electrode 13B, so that the excitation efficiency of the etching gas is improved and the etching rate is improved. It is possible to raise it.

In the second and third embodiments, it is the same as the first embodiment that the object 15 to be processed can be etched uniformly and without damage. Further, the same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

The present invention is not limited to the above-mentioned embodiments, and for example, a microwave may be used as an energy source for exciting the etching gas instead of the high frequency power source.

[0045]

As described above, according to the present invention, the plasma can be concentrated on the object to be processed to improve the processing efficiency, and the plasma is stronger in the peripheral portion of the object than in other portions. Since it can be prevented from acting, it becomes possible to uniformly etch the object to be processed and without damaging the peripheral portion.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a schematic configuration of a plasma processing apparatus showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a flow of plasma in an opening of a plasma control member.

FIG. 3 is a longitudinal sectional view showing a schematic configuration of a plasma processing apparatus showing a second embodiment of the present invention.

FIG. 4 is a longitudinal sectional view showing a schematic configuration of a plasma processing apparatus showing a third embodiment of the present invention.

[Explanation of symbols]

11 ... Chamber 12 ... Placed electrode 13, 13A, 13B ... Counter electrodes 14 ... Placement part 15 ... Object to be processed 17 ... High frequency power source (excitation means) 18 ... Discharge space 21 ... Vacuum pump (pressure reducing means) 25, 25A ... Plasma control member 26 ... Opening 27 ... The first passage 28 ... Second passage

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4G075 AA22 AA30 AA61 BC06 CA15                       CA65 DA02 EA01 EB01 EB42                       EC10 EC21 FB06 FB12 FC15                 4K030 CA04 CA12 FA03 KA14 KA30                       LA11                 5F004 AA01 BA04 BC08

Claims (4)

[Claims] 1. A plasma processing apparatus that excites an etching gas to process an object to be processed, and a chamber into which the etching gas is introduced, and a mounting part disposed in the chamber and on which the object to be processed is placed. A protruding mounting electrode, a counter electrode disposed in the chamber so as to face the mounting electrode, and energy is supplied between the pair of electrodes to excite the etching gas supplied in the chamber. And an exciting means for generating plasma, and an opening having a diameter slightly larger than that of the above-mentioned placing portion and accommodating the above-described placing portion in this opening, and the inner peripheral surface of the opening and the above-mentioned placing portion. A passage is formed between the outer peripheral surface and the pair of electrodes, and the plasma generated by the exciting means is collected in the opening and the plasma separated from the peripheral portion of the object to be treated is passed through the passage. Let go The plasma processing apparatus characterized by comprising a plasma control member made of a gas-insulating material. 2. The plasma processing apparatus according to claim 1, wherein the counter electrode is provided with a protrusion that is accommodated in the opening of the plasma control member. 3. The plasma processing apparatus according to claim 1, wherein an outer dimension of the counter electrode is substantially the same as an inner diameter dimension of the opening of the plasma control member. 4. A plasma processing method for exciting an etching gas to process an object to be processed provided in the chamber, the step of introducing the etching gas into the chamber, and exciting the etching gas into the chamber. And a step of collecting the plasma generated in the chamber on the object to be processed and allowing the plasma deviating from the peripheral portion of the object to be processed without causing the plasma to act on the object. A characteristic plasma processing method.