JP3343819B2 - Ion etching method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material etching technique, and more particularly to a magnetron type ion etching method and apparatus.

[0002]

2. Description of the Related Art A magnetron-type ion etching apparatus (hereinafter referred to as an M-IE apparatus) is equipped with a magnetic field generator in a normal ion etching apparatus (hereinafter referred to as an IE apparatus), and utilizes a magnetic field in addition to an electric field. This is a configuration of FIG. 1 shows an example of such a conventional M-IE device. In FIG. 1, reference numeral 1 denotes a chamber.
A grounded anode electrode 2 and a cathode electrode 4 attached to a cathode support, that is, a substrate stage 3 and opposed to the anode electrode 2 are arranged in parallel. A support 7A of a yoke 7 described below is provided below the cathode support 3.
A cylindrical portion 3A is provided to penetrate and fix. A substrate 5 as a sample is placed on the surface of the cathode electrode 4 on the side facing the anode electrode 2. A permanent magnet 6 is arranged near the lower portion of the cathode electrode 4, that is, on the back side of the cathode support 3. Reference numeral 7 denotes a yoke that forms a magnetic path of the magnet 6. 8 indicates a magnetic flux passing from the magnet 6 to the sample 5. Reference numeral 9 denotes an insulator interposed between the cathode support 3 and the cathode support 3 when the cathode support 3 is mounted in the chamber 1. Reference numeral 10 denotes a cooling water outlet pipe provided on the cathode support 3. Reference numeral 20 denotes a gas inlet for introducing a gas into the chamber 1, and reference numeral 21 denotes a vacuum pump system for evacuating the chamber 1. A high frequency power from a high frequency (RF) power supply 15 is supplied to the cathode electrode 4 by the matching box 16 and the cathode support 3.
Is applied. Reference numeral 17 denotes a high-frequency voltmeter for measuring the output voltage of the matching box 16.

In an M-IE device in which an electric field E and a magnetic field B are orthogonal to each other, electrons in a cathode sheath perform cyclotron motion. This movement increases the probability that neutral atoms and molecules collide with electrons, thereby increasing the ionization probability.
Thus, a high-density plasma (a large amount of ions and electrons) can be formed between the cathode and the anode.

There are four processing parameters in the IE apparatus and the M-IE apparatus: input power, gas pressure, self-bias voltage and magnetic field strength (only the M-IE apparatus) described below.

Usually, when high-frequency power is applied to a cathode electrode in a rare gas, a plasma is thereby formed and a sheath of positive ions is formed on the surface of the cathode electrode. Due to the self-bias voltage in this sheath region, ions between the cathode and the anode are accelerated in the cathode direction and the material is etched.

Even if good anisotropic etching can be performed with a certain gas voltage, power and pressure, if the input power is increased in order to increase the etching rate, the self-bias voltage also increases, resulting in processing. Damage increases.

[0007] Further, in the IE, although a non-uniform magnetic field does not exist, a uniform etching region can be obtained over a wide range, but there is a problem that the etching rate is low due to low plasma density.

The ion sheath is affected by the plasma density distribution. In the M-IE applying a magnetic field, the distribution of the magnetic field intensity causes the distribution of ions in the plasma density and the sheath region. Is high and the density is low where the strength is low. Due to the distribution of these plasma densities, the etching area could not be made uniform.

[0009]

As described above, the M-IE apparatus uses a magnetic field, so that the etching rate is higher than that of the IE apparatus, and is superior from an industrial viewpoint such as high-speed processing, low damage, and high selectivity. Has the characteristics
Since the applied magnetic field intensity has a distribution, a uniform etching region could not be obtained. Therefore, it is important to make the etching distribution uniform.

An object of the present invention, by rotating the magnetic field, removes the deficiencies of the prior art described above, and times
It is an object of the present invention to provide an ion etching method and apparatus capable of performing high-speed and high-quality etching with a large area and uniformity by devising an arrangement shape of a magnet to be rotated .

[0011]

To achieve this object, a method according to the present invention comprises placing a first and a second electrode in a vacuum chamber parallel to each other, grounding the first electrode, A high-frequency power is supplied to the second electrode, a sample is placed on the main surface of the second electrode facing the first electrode, and a magnet is placed below the other main surface of the second electrode. Place ,
Using a magnetron-type ion etching apparatus capable of rotating the magnet , the magnet is rotated so that the etching region formed on the second electrode during ion etching is always uniform, and the high-frequency power and the vacuum chamber regardless of the pressure of the gas introduced into the inside, an ion etching method to be set, the magnet
Are located within a plane along the surface of the second electrode.
A plurality of shapes that are almost fan-shaped open from the center to the outer periphery
The magnet and each of the plurality of substantially sector-shaped magnets have polarities
Are different from each other in the outer periphery of each of the plurality of substantially sector-shaped magnets.
The plurality of substantially sector-shaped magnets are arranged on the outside so as to face each other.
And a plurality of magnets are arranged, said substantially sector-shaped
Are formed, the S pole and the N pole are circumferential in the plane.
And the magnets are arranged alternately in
The shape of the sector is a plurality of
Magnetic flux leaking from the magnet to the surface of the second electrode
Is radially outward from the center of the second electrode.
Characterized in that the shape increases in proportion to .

In the apparatus of the present invention, a first electrode and a second electrode are arranged in a vacuum chamber in parallel with each other, the first electrode is grounded, high frequency power is supplied to the second electrode, and the second electrode is Placing a sample on the main surface on the side facing the first electrode, disposing a magnet below the other main surface of the second electrode ;
A magnetron-type ion etching apparatus in which the magnet is rotatable, wherein the magnet is located along a surface of the second electrode.
A substantially sector shape from the center of the second electrode to the outer periphery in a plane
A plurality of magnets having an open shape and a plurality of substantially fan-shaped magnets
The polarity is different from each of the magnets,
The plurality of substantially sector-shaped magnets are provided outside the outer circumference of each of the magnets.
Multiple magnets placed opposite each stone
And the plurality of substantially fan-shaped magnets are
The S pole and the N pole are alternately arranged in the circumferential direction in the plane.
The substantially sector shape of the plurality of magnets is
From the plurality of substantially sector-shaped magnets in the second electrode
The magnetic flux leaking toward the surface is half a distance from the center of the second electrode.
The shape increases radially outward in proportion to the distance.
Characterized in that that.

[0013]

According to the present invention, the permanent magnets arranged on the back side of the substrate stage can be rotated with respect to the substrate stage
At the same time, the arrangement of the magnets was devised , so that the etching depth per unit time, that is, the etching rate can be made uniform by appropriately determining the distribution of the ion sheath and plasma formed on the substrate stage during discharge. it can. The etching rate increases when the plasma density on the substrate stage increases when the self-bias voltage is constant, and decreases when the plasma density decreases. Therefore, the arrangement of the etching region and the permanent magnet can be set based on the relationship between the plasma density (magnetic flux density) on the substrate stage surface and the etching rate.

In order to solve the above-mentioned problem, the present inventors have reduced the self-bias voltage value by using a permanent magnet having a large magnetic field strength and increasing the applied magnetic field strength by about an order of magnitude compared to the prior art. The desired values could be obtained. Furthermore, by properly arranging the magnet,
Having a desired etching area distribution on the substrate stage,
By combining this etching area distribution control and the magnetic field rotating mechanism, an etching area having a uniform depth over a wide range on the substrate stage could be obtained.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 2 shows the configuration of an embodiment of the ion etching apparatus of the present invention. In this apparatus, the same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

A cylindrical portion 3A provided on the cathode support 3 slidably supports the yoke support 7A, and an O-ring 11 is provided inside the cylindrical portion 3A to hermetically seal the inside of the chamber 1. Arrange. A gear knob 12 is formed below the column 7A. A gear 13 made of an insulator is engaged with the gear knob 12. The gear 13 is driven stepwise by a stepping motor 14 so as to rotate the column 7 around the axis.
It can control up to 00 rpm. Note that the stepping motor 14 may be a normal motor. According to the above configuration, the magnet 6 can rotate.

The stepping motor 14 rotates the permanent magnet to make the etching rate uniform.

In this embodiment, an electromagnet may be used instead of the permanent magnet 6, but a permanent magnet is preferable as the movable and rotatable magnet having a strong magnetic field, and the material is samarium cobalt. Rare earth magnets are suitable.

This device operates as follows. First, the chamber 1 is approximately 1 × 1 by the vacuum pump system 21.
After evacuating to about 0 ^-7 Torr, the gas inlet 2
From 0, the etching gas, for example, O ₂ gas is 1 × 10 ^−3.
Introduce until Torr. Next, when RF power is applied to the cathode electrode 4 by the RF power supply 15, a discharge is generated between the cathode electrode 4 and the anode electrode 2, and plasma is formed. At this time, the substrate 5 is placed on the cathode electrode 4 placed on the cathode support 3 and is cooled by the cooling water flowing from the cooling water outlet pipe 10. A certain self-bias voltage is induced in the high-frequency wattmeter 17 by the above-described discharge. Here, the permanent magnet moving gear knob 12, the insulator gear 13, and the stepping motor 1
By using 4, the permanent magnet 6 can be rotated in the direction of the arrow in the figure, that is, under the substrate 5.
With this mechanism, the rotation speed of the permanent magnet is set to 0 to 2000 rpm.
m can be controlled.

FIG. 3 shows the magnetic field dependence of the etching rate for designing the magnetic field. The etching conditions are power density 2
W / cm ² , etching gas; argon, sample; tungsten, gas pressure 1 × 10 ⁻² Torr, substrate temperature 20 ° C. As the magnetic field increases, the etching rate monotonically increases and reaches a maximum at 500 Gauss. Further increases will decrease the rate monotonically.

Next, a magnetic field is designed based on this figure. A design example is described below. First, a schematic view of the arrangement of the cathode permanent magnet is shown in FIG.

The magnet design of this cathode is such that the magnet arrangement is such that the average magnetic field strength per unit time per unit area during rotation is constant, that is, the permanent magnets are arranged so that the magnetic field strength is proportional to the radial distance at the time of stop. It is an example of the arrangement. The magnet material is the same, and the magnetizing moment is constant in all parts of the magnet. Here, the shape of the magnet will be described.
Assume that the center of the circle is the origin 0, the x-axis and the y-axis are taken as shown in the figure, the magnet is composed of four parts, and the S pole and the N pole are alternately arranged. In the magnet arrangement of FIG.
Is that of a plurality of S-poles and N-poles that are alternately arranged
On the outside of each circumference, arc-shaped
A magnet is located. That is, the overall arrangement of the magnets
Therefore, in the circumferential direction (rotational direction), an almost sector-shaped S pole and N pole
Are arranged alternately facing each other, and outwardly in the radial direction.
Magnets of opposite polarity are arranged opposite each of the sector-shaped S pole and N pole
It is the shape that has been done.

[0024]

[Outside 1]

[0025]

[Outside 2]

[0026]

[Outside 3]

[0027]

[Outside 4]

In the cathode designed by the above method,
The leakage magnetic field on the cathode surface was measured in the radial direction. In this case, 1 was 15 cm, and the gap between the S pole and the N pole in the outer peripheral portion was 2 cm. FIG. 5 shows the results. As designed, the leakage magnetic field is approximately 5 in proportion to the radial direction from the center.
It increased to 00 gauss and the desired magnetic field distribution was obtained.

As the backing plate on the cathode surface, a composite plate with a magnetic shielding material such as permalloy is used, and by changing the thickness of the plate, the average leakage magnetic field intensity over the entire target surface is optimized (from the central magnetic field intensity). The average magnetic field strength is set in advance so that the etching rate is proportional to the magnetic field strength at the outer periphery.).

In the above description, the number of magnets in which the S pole and the N pole are paired is four. However, two or eight magnets may be used. If the number is eight or more, leakage of the magnetic field lines to the outside is reduced, which is not appropriate. Of the two-, four-, and eight-sheet configurations,
The four-sheet configuration is most suitable in view of the magnetic field distribution and the leakage of the magnetic field lines.

Further, as described above, the specific dimension of l is suitably 15 cm, for example, and the gap between the S pole and the N pole in the outer peripheral portion is suitably about 2 cm.

Further, in order to actually process the outer peripheral shape of the magnet represented by y = f (x), a method of repeating linear processing in multiple stages is adopted, and the processing linear width is set within a range where cost is attractive. This is dealt with by making it smaller (more steps).

Further, in the above-described magnet arrangement, the center ends of the respective magnet pieces are made coincident. However, in practice, there is no problem if the respective ends are made coincident, separated, or even overlapped.
Therefore, it may be appropriately selected in actual processing.

Next, the uniformity of the etching depth when the cathode was etched by rotating the magnet for one hour was examined. FIG. 6 shows the results. As is clear from the figure, the etching is uniform except for the center and the outer periphery.

Similarly, other materials (a dielectric such as SiO ₂ ,
In the case of etching a magnetic material such as CoCr), etching was performed at a uniform depth by using the same method as described above.

[0036]

As described above, according to the present invention, by rotating the permanent magnet disposed on the back surface side of the substrate stage with respect to the substrate stage, the etching area formed on the substrate stage at the time of discharge can be reduced. The etching can be uniform over a wide area, and uniform depth etching can be performed over a large area. For this reason, the present invention is suitable for processing such as pattern formation of parts and the like in an industrial process that requires a high-speed, large-area, uniform etching region.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a conventional example.

FIG. 2 is a configuration diagram showing one embodiment of the present invention.

FIG. 3 is a diagram showing a magnetic field strength dependency of an etching rate for a magnetic field design.

FIG. 4 is a plan view schematically showing a cathode permanent magnet.

FIG. 5 is a characteristic diagram showing a relationship between a magnetic field strength and a distance from a cathode center.

FIG. 6 is a characteristic diagram showing a relationship between an etching depth and a distance from a cathode center.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Chamber 2 Anode electrode 3 Cathode support base (substrate stage) 3A cylindrical part 4 Cathode electrode 5 Substrate 6 Permanent magnet 7 Yoke 7A Column 8 Magnetic flux 9 Insulator 10 Cooling water outlet pipe 11 O ring 12 Gear knob 13 Insulator gear 14 Stepping Motor 15 RF power supply 16 Matching box 17 High frequency voltmeter 20 Gas inlet 21 Vacuum pump

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C23F 4/00 H01L 21/3065

Claims (2)

(57) [Claims] A first electrode disposed in the vacuum chamber in parallel with the second electrode, the first electrode being grounded, and
High-frequency power is supplied to the electrode, placing the sample on the said main surface of the first electrode opposite to the side of the second electrode, a magnet is disposed on the lower side of the other main surface of the second electrode The magnet can be rotated
A magnetron type ion etching apparatus and ability,
The magnet is rotated so that the second
Etching region formed in the electrode, always uniform, and the independently of the RF power and pressure of the gas introduced into the vacuum chamber, an ion etching method to be set, the magnet Is in a plane along the surface of the second electrode.
A shape that opens almost in a fan shape from the center of the two electrodes to the outer periphery
Each of the plurality of magnets and the plurality of substantially fan-shaped magnets
Different in polarity from each of the plurality of substantially sector-shaped magnets.
Each of the plurality of substantially sector-shaped magnets
And a plurality of magnets, which are substantially fan-shaped , are arranged in the plane with an S pole.
N poles are alternately arranged in the circumferential direction.
The substantially sectorial shape of the magnet of
From a plurality of sector-shaped magnets toward the surface of the second electrode
The leaked magnetic flux is radially outward from the center of the second electrode.
An ion etching method having a shape that increases in proportion to the distance toward the ion etching. 2. A method according to claim 1, wherein a first electrode and a second electrode are arranged in a vacuum chamber in parallel with each other, said first electrode is grounded,
High-frequency power is supplied to the electrode, placing the sample on the said main surface of the first electrode opposite to the side of the second electrode, a magnet is disposed on the lower side of the other main surface of the second electrode The magnet can be rotated
Magnetron ion etching apparatus was Noh met
The magnet is positioned in a plane along the surface of the second electrode.
A shape that opens almost in a fan shape from the center of the two electrodes to the outer periphery
Each of the plurality of magnets and the plurality of substantially fan-shaped magnets
Different in polarity from each of the plurality of substantially sector-shaped magnets.
Each of the plurality of substantially sector-shaped magnets
And a plurality of magnets, which are substantially fan-shaped , are arranged in the plane with an S pole.
N poles are alternately arranged in the circumferential direction.
The substantially sectorial shape of the magnet of
From a plurality of sector-shaped magnets toward the surface of the second electrode
The leaked magnetic flux is radially outward from the center of the second electrode.
An ion etching apparatus having a shape that increases in proportion to the distance toward the ion etching apparatus.