JP3165941B2 - Plasma processing apparatus and method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a plasma processing apparatus and a plasma processing apparatus.
Regarding the method .

[0002]

2. Description of the Related Art In a process of processing a semiconductor wafer, dry etching is performed for, for example, separating a capacitor or an element or forming a contact hole.
A parallel plate type plasma processing apparatus is known as a typical conventional apparatus for performing the dry etching.

FIG. 7 is a view showing a parallel plate type plasma processing apparatus. A mounting table 11 serving also as a lower electrode is disposed in an airtight chamber 1 and is opposed to and above the mounting table 11. An upper electrode 12 also serving as a gas supply unit is provided. 13 is an exhaust pipe.

In such a plasma processing apparatus,
First, the wafer W is mounted on the mounting table 11 and the gas supply unit 12
, A high-frequency power is applied between the electrodes 11 and 12 by a high-frequency power source E to generate plasma, and reactive ions in the plasma generate wafers W.
Is etched.

[0005] By the way, the line width of the pattern of the device tends to be finer, but the pressure in the chamber when the plasma is generated in the above-described apparatus is 100 mTo.
rr to 1 Torr. At such a high pressure, the mean free path of ions is small, so that fine processing is difficult.
In addition, although the diameter of a wafer is increasing, if the mean free path of ions is small, high uniformity of plasma distribution over a wide surface cannot be secured, so that uniform processing of a large-diameter wafer is difficult. There are also problems.

Therefore, recently, as described in European Patent Publication No. 379828 and Japanese Patent Application Laid-Open No. 3-79025, the upper surface of the chamber 1 facing the mounting table 11 is made of an insulating material such as quartz glass. Along with
A planar coil is fixed outside the insulating material, a high-frequency current is passed through the coil to form an electromagnetic field in the chamber 1, and electrons flowing in the electromagnetic field collide with neutral particles of the processing gas to generate plasma. A high-frequency induction method for generation is being studied.

According to this method, a substantially concentric electric field is induced in accordance with the shape of the coil, and there is an effect of confining the plasma. Therefore, the plasma is generated at a considerably lower pressure than that of the conventional parallel plate type plasma processing apparatus. Therefore, the mean free path of ions in the generated plasma is large, and therefore, the etching process using this plasma is suitable for fine processing. Then, the plasma diffuses from the high-density region to the low-density region, but the plasma has a large mean free path, so the plasma density distribution is smooth, and the plasma uniformity in a plane parallel to the wafer plane is high.
In-plane uniformity of plasma processing for a large-diameter wafer is improved.

[0008]

As described above, the high-frequency induction method is attracting attention as a method suitable for miniaturizing the line width of a pattern and increasing the diameter of a wafer. There is a problem. For example, one of them is
Since the high-frequency antenna is provided outside the chamber,
When a large power is applied to the antenna, radio wave interference occurs in the surroundings, so that the high-frequency antenna must be covered with a shield, which causes a problem that the device becomes large and complicated. When the upper surface of the chamber is made of quartz and a high-frequency antenna is mounted on it, the portion in contact with the antenna is locally heated when power is applied because the thermal conductivity of quartz is small, so that large heat is applied to the quartz. There is a possibility that a stress is generated and a crack occurs, which may lead to an accident of rupture of the chamber.

The present invention has been made under such circumstances, and an object of the present invention is to provide an apparatus for processing an object to be processed by plasma obtained by applying high-frequency power to a high-frequency antenna comprising a coil. The object is to reduce the size of the device.

[0010]

A plasma processing apparatus according to the present invention.
The device is an airtight structure made of grounded conductive material.
And an object to be processed, which is provided in the chamber and
Mounting table and means for supplying a processing gas into the chamber
When the chamber so as to partition the space of the chamber
Insulated and corrosion resistant material provided opposite to the mounting table
The partition plate of the material and the mounting table described above on this partition plate
-Frequency antenna consisting of a planar coil provided as
For applying high frequency power to this high frequency antenna
A high-frequency power supply unit;
The processing gas is turned into plasma by the
Processing the object on the mounting table by plasma
And The partition plate is made of ceramic, for example.

A plasma processing apparatus according to another invention is grounded.
A chamber of the airtight structure composed of conductive material, the tea
Provided within Nba, the mounting table for mounting the object to be processed, wherein
Means for supplying a processing gas into the chamber; and the chamber
From a flat coil provided facing the mounting table inside
High frequency antenna and insulation covering this high frequency antenna
Container made of a conductive and corrosion-resistant material and the high-frequency antenna
And a high-frequency power supply for applying a high-frequency power.
The processing electric field is generated by the alternating electric field generated from the high-frequency antenna.
The plasma on the mounting table
It is characterized by processing a physical body.

In the above invention, the high-frequency antenna is cooled.
It is preferable to provide a cooling means for cooling. In addition, high frequency
Frequency lower than the frequency of the high frequency voltage applied to the antenna
A high frequency power supply for applying a number of bias voltages.
A configuration is preferred.

In the plasma processing method of the present invention, a grounded
Space of the chamber in a chamber made of conductive material
A plane provided on the partition plate facing the mounting table
High-frequency power is applied to a high-frequency antenna consisting of a coil
A step of high-frequency antenna, wherein the high-frequency power was applied
Process gas is turned into plasma by the alternating electric field emitted from
Then, the object to be processed on the mounting table is processed by the plasma.
And a step.

[0014]

According to the present invention, by providing a high-frequency antenna in a chamber and grounding the chamber, the chamber plays a role of a shield, so that even if high-frequency power is applied to the high-frequency antenna, radio wave interference occurs in the surroundings. There is no need to provide a high-frequency antenna and a shield outside the chamber, so that the device is reduced in size and simplified .

[0015]

1 and 2 are a cross-sectional view showing an entire configuration of a plasma processing apparatus, for example, an etching apparatus according to an embodiment of the present invention, and a schematic exploded perspective view with a part cut away. 2 in the figure
Is a chamber having an airtight structure made of aluminum and grounded. A mounting table 3 made of, for example, aluminum is disposed at a central bottom in the chamber 2.

The mounting table 3 is a mounting section 3 which is an upper portion.
1 and a supporting portion 32 which is a lower portion for supporting the mounting portion 31 are detachably connected by bolts 33, and an insulator 34 is provided between the supporting portion 32 and the chamber 2.
Is interposed. The electrostatic chuck sheet 4 is provided on the upper surface of the mounting portion 31 so as to cover the upper surface.
The electrostatic chuck sheet 4 is configured by covering a conductive film 41 as an electrode for an electrostatic chuck sheet made of, for example, copper foil from both sides with an insulating film 42 made of, for example, a polyimide film. Is electrically connected to an external DC power supply 43 via a switch 44.

The upper end of the mounting section 31 is the mounting section 3
A plurality of holes 51 for a backside gas (gas for heat conduction) are formed on the upper surface of the first side 1. It communicates with the supply path 53. Holes (not shown) are formed in the electrostatic chuck sheet 4 at positions corresponding to the holes 51, and the backside gas from the holes 51 passes through the holes of the electrostatic chuck sheet 4 to the back surface of the wafer W. It can be sprayed. The gas supply path 53
Is connected to a gas supply source such as He gas (not shown) via a pressure regulator 54 such as a butterfly valve.

The pressure of the backside gas blown toward the back surface of the wafer W from the hole 51 is determined in the ventilation chamber 52 based on the pressure detection value of the pressure detection unit 555 for detecting the pressure of the backside gas. Value eg 10To
It has a function of adjusting the opening degree of the pressure regulator 54, for example, the butterfly valve, so as to be rr.

An annular focus ring 21 surrounding the wafer W is disposed on the mounting portion 31. The focus ring 21 is made of an insulating material that does not attract reactive ions, and has a role of effectively attracting the reactive ions to the inner wafer W.

A coolant reservoir 35 for circulating a cooling medium for cooling the wafer W via the mounting table 3 is formed inside the support portion 32. The coolant reservoir 35 has an inlet pipe 36A and an outlet pipe 36B. A cooling medium, such as liquid nitrogen, which is provided and supplied into the refrigerant reservoir 35 via the introduction pipe 36A is discharged to the outside of the apparatus via the discharge pipe 36B.

In the vicinity of the upper surface in the chamber 2, a high-frequency antenna 6 composed of a planar coil, for example, a spiral coil is opposed to the mounting table 2 by a fixing member 23 made of an insulating material, for example, a fluororesin (see FIG. 2). It is provided fixed to the chamber 2. This high-frequency antenna 6 is formed of a tubular body made of a conductive material such as aluminum, and its outer peripheral surface and inner peripheral surface are coated with a corrosion-resistant material such as aluminum oxide to prevent corrosion by a processing gas. ing.

An outer end of the high-frequency antenna 6 is connected to one end of a gas supply pipe 7 for supplying a processing gas to the high-frequency antenna 6, that is, the internal space of the tubular body. A supply source of a processing gas (not shown) or a processing gas such as CHF3 or CF4 in the case of etching is connected to the side. The high-frequency antenna 6
As shown in FIG. 3, an outlet for processing gas, for example, a gas outlet 71, which communicates the internal space of the tubular body with the outside (the space in the chamber 2), is formed along the coil as shown in FIG.

Between both terminals (inner terminal and outer terminal) of the high-frequency antenna 6, for example, 13.56 from a high-frequency power supply 61 for plasma generation via a matching circuit 62.
A high frequency voltage of 1 MHz is applied. As a result, a high-frequency current flows through the antenna 6, and plasma is generated in a space directly below the antenna 6 as described later. On the upper surface side of the high frequency antenna 6, a cooling means for cooling the high frequency antenna 6, for example, a cooling plate 8 is provided. The cooling plate 8 is, for example, a refrigerant pipe 81
Thereby, a refrigerant, for example, cooling water flows therein. When the high-frequency antenna 6 is cooled in this way, there is an advantage that the peeling of the corrosion-resistant material due to the difference in the thermal expansion coefficient between the material of the antenna and the corrosion-resistant material on the outer peripheral surface can be suppressed.

The high-frequency power supply 22 is provided between the mounting table 3 and the ground to apply a bias voltage, for example, 400 KHz, lower than the frequency of the high-frequency voltage applied to the high-frequency antenna 6 to the mounting table 3. Is connected. The chamber 2 is connected to the ground, so that an electric field is formed between the mounting table 3 and the chamber 2,
As a result, the perpendicularity of the reactive ions in the plasma in the chamber 2 to the wafer W is increased.

One end of a plurality of exhaust pipes 24 is connected to the bottom surface of the chamber 2 at equal intervals in the circumferential direction of the chamber 2. In the illustrated example, one ends of the two exhaust pipes 24 are symmetrically connected to the axis of the chamber 2. The other ends of the exhaust pipes 24 are connected to a common exhaust pipe 27 in which a pressure regulator 25 such as a butterfly valve and a vacuum pump 26 are interposed, as shown in FIG. Further, in this embodiment, the exhaust system is provided with a pressure detecting unit provided in the chamber 2 so as to gently evacuate the particles at the beginning of evacuation so as not to wind up the particles, and to evacuate the particles quickly after evacuation to some extent. The exhaust controller 29 is configured to adjust the pressure regulator 25 based on the detected pressure value from.

Next, the operation of the above embodiment will be described.
First, an object to be processed, for example, a wafer W, is loaded into the chamber 2 by a transfer arm (not shown) and placed on the electrostatic chuck sheet 4. Then, the chamber 2 is evacuated to a predetermined vacuum atmosphere through the exhaust pipe 24 by the vacuum pump 26, and an etching gas such as CF4 gas is supplied from the gas supply pipe 7 through the internal space of the high-frequency antenna 6 to the chamber 2 through the blowing hole 71. The inside of the chamber 2 is evacuated by evacuation from the exhaust pipe 24 while supplying the
r and a high frequency voltage is applied to the high frequency antenna 6 from the high frequency power supply unit 61. When a high-frequency current flows through the high-frequency antenna 6 due to the application of the high-frequency voltage, an alternating magnetic field is generated around the antenna conductor, and most of the magnetic flux passes through the center of the antenna in the vertical direction to form a closed loop. Such an alternating magnetic field induces an alternating electric field in a circumferential direction substantially concentrically right below the antenna 6, and the electrons accelerated in the circumferential direction by the alternating electric field collide with neutral particles of the processing gas. Is ionized to generate plasma. The surface of the wafer W is etched by the reactive ions in the plasma thus generated.

When high-frequency power is applied to the high-frequency antenna 6 as described above, radio waves tend to spread to the surroundings. However, since the chamber 2 is made of aluminum material and grounded, the chamber 2 is shielded by this chamber 2 and, therefore, the device is not used. There is no risk of radio interference to the surroundings. Although the size of the apparatus can be reduced by the amount that the high-frequency antenna 6 does not exist outside the chamber 2, a particularly advantageous point is that the high-frequency antenna 6
When the shield body is provided outside the chamber 2 and the shield body is disposed outside the chamber 2, the outer wall surface of the chamber 2 must be processed. However, such a processing is not required if the chamber 2 is used as a shield body. And the shield is chamber 2
Since it is not arranged outside the device, the size and simplification of the device can be achieved.

Further, since the high-frequency antenna also serves as the processing gas introduction section, the structure is simpler than when a processing gas supply section is separately provided along the outer peripheral portion of the high-frequency antenna, for example. By forming the processing gas blowout holes 71 along the periphery of the coil, these overlap with the projection surface of the wafer W on the mounting table 3 and, furthermore, since the blowout holes 71 are arranged in a coil shape, Can be supplied with high uniformity, and uniform plasma processing can be performed. However, the gas outlet may be a slit instead of a hole. Further, since the high-frequency antenna 6 is cooled from the inside by the flow of the processing gas, the cooling effect can prevent the corrosion-resistant material adhered to the inner and outer peripheral surfaces of the high-frequency antenna 6 from peeling off.

FIGS. 4 and 5 show another embodiment of the present invention. In the embodiment shown in FIG. 4, an annular protruding wall 72b is formed at the periphery of the lower surface of the cylindrical portion 72a, and these internal spaces are used as ventilation chambers.
3 are formed along the circumferential direction to constitute a processing gas supply unit. The processing gas supply unit communicates with a gas mixing chamber 74, and a plurality of gas supply pipes 75 (two in the illustrated example) are connected to the gas mixing chamber 74. And annular protruding wall 7
2b, a high-frequency antenna 6 is provided on the cooling plate 8
It is placed and arranged on top. In such a configuration,
Since a plurality of types of processing gases are mixed by the gas mixing chamber 74, a processing gas having a uniform component can be supplied to the surface of the wafer W. As a material of the processing gas supply unit, for example, alumina-based ceramics, SiC, or the like can be preferably used. The former material is hard to be cut by the halogen gas, and the latter material has no adverse effect on the wafer because it is a silicon-based component even if it is cut.

In the embodiment shown in FIG. 5, the processing gas supply unit is provided with a cylindrical body 7 having a large number of gas blowing holes 76 on the lower surface.
7, and a high-frequency antenna 6 is provided therein. Although the cooling plate 8 for cooling the high-frequency antenna 6 is shown in the examples of FIGS. 4 and 5, this is not always required. When the high-frequency antenna is provided in the chamber, the high-frequency antenna may be covered with a container made of an insulating and corrosion-resistant material. Alternatively, as shown in FIG. The high frequency antenna 6 may be placed on the plate 9 and placed thereon.

Although the above description has been made with reference to the example of the etching process as the plasma process, the present invention relates to a plasma CV
It can be applied to other plasma processing apparatuses such as D apparatus, plasma ashing apparatus, and plasma sputtering apparatus.
The object to be processed is not limited to a semiconductor wafer, but may be an LCD substrate or the like.

[0032]

According to the present invention, by providing a high-frequency antenna in a chamber and grounding the chamber,
Since the chamber plays the role of a shield, even if high-frequency power is applied to the high-frequency antenna, no radio interference will occur around the high-frequency antenna.In addition, since the high-frequency antenna and the shield need not be provided outside the chamber, the device can be downsized. be simplified
You.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the overall configuration of an embodiment of the present invention.

FIG. 2 is a schematic exploded perspective view schematically showing the overall configuration of the embodiment of the present invention.

FIG. 3 is a bottom view showing the high-frequency antenna.

FIG. 4 is a sectional view showing a part of another embodiment of the present invention.

FIG. 5 is a sectional view showing a part of still another embodiment of the present invention.

FIG. 6 is a sectional view showing a part of still another embodiment of the present invention.

FIG. 7 is a cross-sectional view showing a conventional example of a plasma processing apparatus.

[Explanation of symbols]

 Reference Signs List 2 chamber 3 mounting table 35 refrigerant reservoir 4 electrostatic chuck sheet 53 backside gas supply pipe 6 high-frequency antenna 61 high-frequency power supply unit 7 gas supply pipe 71, 73 gas blowing hole 74 gas mixing chamber

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁷ Identification code FI H01Q 9/27 H01L 21/302 CH

Claims (6)

(57) [Claims] An airtight structure made of a grounded conductive material.
Chamber and a mounting table provided in the chamber for mounting an object to be processed.
If, means for supplying a process gas into said chamber, in said chamber so as to partition the space of the chamber
It is provided opposite to the mounting table and is made of insulating and corrosion-resistant material.
A partition plate, and a flat plate provided on the partition plate so as to face the mounting table.
A high-frequency antenna consisting of a planar coil and a high-frequency antenna for applying high-frequency power to this high-frequency antenna
And a wave power supply unit.
The processing gas is turned into plasma by the alternating electric field
Processing the object to be processed on the mounting table by
Plasma processing equipment. 2. The partition plate is made of ceramics.
The plasma processing apparatus according to claim 1, wherein: 3. An airtight structure made of a grounded conductive material.
And a chamber of A mounting table provided in this chamber for mounting the object to be processed
When, Means for supplying a processing gas into the chamber; A planar shape provided opposite the mounting table in the chamber
A high-frequency antenna comprising a coil of The insulating and corrosion-resistant material covering the high-frequency antenna
Vessels, High frequency for applying high frequency power to the high frequency antenna
And a wave power supply unit.
The processing gas is turned into plasma by the alternating electric field
Processing the object to be processed on the mounting table by
Plasma processing equipment. 4. A cooling means for cooling a high-frequency antenna is provided.
4. The plug according to claim 1, 2 or 3, wherein
Plasma processing equipment. 5. A high-frequency voltage applied to a high-frequency antenna
Frequency lower than the frequency of High applying wavenumber bias voltage
2. The apparatus according to claim 1, further comprising a frequency power supply unit.
5. The plasma processing apparatus according to any one of items 4. 6. A mounting table is provided in a chamber having an airtight structure,
A processing gas is introduced into the chamber to generate plasma, and
Plasma processing the object on the mounting table by the plasma
In the processing method, In a chamber made of a grounded conductive material,
Provided on a partition plate that partitions the space
High-frequency antenna consisting of a flat coil
Applying power; Emitted from the high-frequency antenna to which the high-frequency power is applied.
The processing gas is turned into plasma by the alternating electric field
Processing the object to be processed on the mounting table with the
A plasma processing method.