JP3037848B2 - Plasma generating apparatus and plasma generating method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma generating apparatus and a plasma generating method applied to thin film formation and etching.

[0002]

2. Description of the Related Art In recent years, plasma processing has been widely used in semiconductor manufacturing processes requiring fine processing. Generally, as a device for performing a plasma process, for example, a cylindrical plasma etching device, a parallel plate plasma etching device, a microwave plasma etching device, and the like are known. In addition, a magnetron etching apparatus for converting a processing gas into plasma (magnetic field plasma) by magnetron discharge using a high-frequency electric field and a magnetic field has been developed. In a magnetron etching apparatus, the generation efficiency of plasma is increased by applying a magnetic field to the plasma.

Hereinafter, a conventional example of a plasma processing apparatus and a plasma processing method will be described with reference to the drawings.

FIG. 17 schematically shows a front sectional structure of a conventional plasma processing apparatus, and FIG. 18 schematically shows a plan sectional structure thereof. In both figures, 1 is a processing chamber, 2 is a cathode, 3 is an anode, 4 is a material to be processed, 5 is a power source, 6 is a gas inlet, 7 is an exhaust port, and 8 is a magnetic field applying device.

[0005] As shown in FIG.
It is installed above. The power supply 5 is connected to the cathode 2 and the anode 3 is grounded. The processing chamber 1 has a gas inlet 6
The processing gas is introduced from. The processing gas is, for example, CHF ₃
The gas is set to 50 sccm. The inside of the processing chamber 1 is evacuated through the exhaust port 7 to be controlled to a reduced pressure of, for example, 5 Pa. Thereafter, 13.56M for example from the power supply 5
A high frequency power of 800 Hz is supplied to a space between the cathode 2 and the anode 3 to generate plasma. The direction of the electric field 9 between the cathode 2 and the anode 3 is indicated by an arrow in FIG.

In the space between the cathode 2 and the anode 3, simultaneously with the application of the electric field, as shown in FIG.
Is applied by the magnetic field applying device 8. Although the electric field 9 in FIG. 17 is not shown in FIG. 18, the electric field is applied perpendicularly to the plane of FIG.

When an electric field 9 and a magnetic field 10 cross each other, charged particles in the plasma receive Lorentz force. Accordingly, the charged particles drift in the direction of arrow D in FIG. 18 while performing cycloidal motion. This drift increases the number of collisions of charged particles. Further, the degree of ionization of the gas is increased, and highly efficient plasma can be obtained. The workpiece 4 is exposed to this plasma, and plasma processing such as etching is performed.

However, in the configurations shown in FIGS. 17 and 18, since the magnetic field 10 is applied in parallel to the material to be processed 4, the drifted charged particles greatly bias the plasma density. In other words, the charged particles move in the direction indicated by arrow D in FIG. 18, that is, toward the top of the paper.
For this reason, positively and negatively polarized charged regions are generated at both ends (upper and lower portions of the sheet) of the material 4 to be processed. Such charge-up damages the workpiece 4 due to static electricity. For example, in a manufacturing process of a semiconductor device, the semiconductor device is broken or deteriorated. Therefore, there is a problem that the yield is reduced when manufacturing a highly integrated semiconductor device.

In order to solve this problem, a method has been adopted in which a magnet is rotated to make the plasma density uniform. FIG. 19 shows a front sectional structure of a conventional magnetron etching apparatus having a rotating magnet. A main part of the magnetron etching apparatus 30 includes a closed processing chamber 21, a pair of upper electrode 22 and a lower electrode 23 which are arranged in the processing chamber 21 so as to be opposed to each other, for example, in a vertical direction. And a high-frequency power supply 3 for supplying high-frequency power to a space between the upper electrode 22 and the lower electrode 23, which is rotatably disposed outside the processing chamber 21 as a magnetic field applying device.
And 2.

The processing chamber 21 is for etching an object therein, for example, a semiconductor wafer A (hereinafter simply referred to as a wafer), which is a substrate to be processed, and is connected to an exhaust port 31 provided at the lower side of the processing chamber. By evacuating by a evacuating means (vacuum pump) 25, the inside thereof is kept in a vacuum. An insulating member 34 insulates between the lower electrode 23 provided in the processing chamber 21 and the side wall of the processing chamber 21. The lower electrode 23 has a disk-shaped susceptor 24 at the upper center thereof.
The wafer A is supported on 4. In order to securely support the wafer A on the susceptor 24, a chuck mechanism, for example, an electrostatic chuck 26 is provided on the susceptor 24 to hold the wafer A by suction.

A disk-shaped space 27 is formed inside the upper electrode 22 so as to face the susceptor 24, and a number of gas diffusion holes 28 are formed in communication with the space 27 toward the inside of the processing chamber 21. Have been. A processing gas supply source 37 is connected to a gas introduction pipe 35 connected to a gas supply path 39 communicating with the space 27 via a mass flow controller 36.
Is connected, and the processing gas (eg, 100 sccm CHF ₃ or the like) supplied from the processing gas supply source 37 is supplied to the space 27.
And into the processing chamber 21 through the diffusion hole 28. In some cases, a means for heating the processing gas to room temperature or higher is provided as needed, and the processing gas is supplied through this heating means.

The lower electrode 23 is provided with a temperature control mechanism (not shown) that can set the temperature of the wafer A to a desired temperature (for example, -100 ° C. to + 200 ° C.). A high-frequency power supply 32 is connected to the lower electrode 23 via a capacitor 33, and one end of the high-frequency power supply 32 is grounded. From the high-frequency power supply 32, a high-frequency power of, for example, 13.56 MHz is supplied between the upper electrode 22 and the lower electrode 23.

The upper electrode 22 outside the processing chamber 21
Is a magnet for generating a magnetic field in the surface direction of the wafer A. The magnet 29 is rotated at a desired rotation speed by a driving mechanism (not shown) such as a motor, thereby forming a magnetic field in a direction crossing the electric field applied to the wafer A.

In order to perform the etching process on the wafer A by the above-configured apparatus, first, the wafer A is loaded into the processing chamber 21 from a preliminary chamber (not shown) via a load lock chamber, and the wafer A is loaded. It is positioned on the electrostatic chuck 26 and sucked. Thereafter, the inside of the processing chamber 21 is evacuated from the exhaust port 31 by the vacuum pump 25, and the degree of vacuum is set to, for example, 5 Pa.

Next, a processing gas is supplied from the space 27 through the diffusion holes 28. When electric power is supplied between the upper electrode 22 and the lower electrode 23 by the high frequency power supply 32, an electric field perpendicular to the surface of the wafer A is generated. At this time, a magnetic field is simultaneously applied to the space between the upper electrode 22 and the lower electrode 23 by the magnet 29, so that a horizontal magnetic field 38 and an electric field crossing the magnetic field 38 are formed on the surface of the wafer A. Magnetic field plasma is generated by magnetron discharge,
The etching of the wafer A is performed by this plasma.

[0016]

According to the conventional magnetron etching apparatus provided with the rotating magnet, the plasma density can be made uniform when the time average is taken. However, at a certain moment, the plasma density is still biased.

FIG. 20 is a schematic plan view showing an instantaneous relationship between a magnetic field 38 and a wafer A as a substrate to be processed in the magnetron etching apparatus 30 of FIG. FIG.
0, a section orthogonal to the magnetic field 38 (XX section, P-
FIG. 21 shows the distribution of the plasma density, the etching rate (etch rate: E / R), and the potential (V _DC ) on the (Q plane). Due to the drift of the charged particles in the direction of arrow D in FIG. 20 due to the Lorentz force, as shown in FIG.
The plasma density on the PQ surface of the wafer A and the etching rate (E / R) decrease from P to Q, and the potential (V _DC )
Increases conversely. That is, the plasma density becomes non-uniform and the potential (V _DC ) becomes non-uniform, and positively and negatively polarized charged regions are generated at both ends of the wafer A. Such a charge-up phenomenon causes dielectric breakdown of the gate oxide film of the wafer A or deteriorates its characteristics. Also,
Since the potential (V _DC ) has a gradient in the plane of the wafer A, the wafer A
It is considered that the ion sheath also has an inclination in the plane, and there is also a problem that the etching shape is bent because the ions travel in a direction perpendicular to the sheath.

Although there is an etching method for reducing the plasma density to such an extent that the wafer A is not damaged, this method has a problem that the etching rate (E / R) decreases and the throughput decreases.

An object of the present invention is to provide a plasma generation apparatus and a plasma generation method capable of reducing the bias of plasma and suppressing charge-up of a material to be processed in view of the above problems.

[0020]

In order to solve the above problems, in the present invention, an electric field and a magnetic field are applied to the plasma space so as to diverge the drift direction of charged particles in the plasma.

More specifically, a first aspect of the present invention is a plasma generating apparatus for converting a gas in a chamber holding a reduced pressure into a plasma by magnetron discharge using an electric field and a magnetic field. At least two electrodes installed in the chamber so as to apply an electric field for ionizing the gas to the space, and charged particles generated from gas in the space in a direction crossing the electric field by the electrodes and Lorentz each. A configuration is provided that includes a magnetic field applying device for applying a magnetic field to the space so as to drift in directions in which they diverge under a force.

In the plasma generator according to the second aspect of the present invention, at least two electrodes installed in the chamber so as to apply an electric field for ionizing gas in a space between each other to the space. And a magnetic field applying device for applying a magnetic field to the space in a direction crossing the electric field generated by the electrodes. However, the magnetic field applied by the magnetic field applying device has a gradient in which the magnetic flux density becomes weaker in the direction of drift of the charged particles due to Lorentz force acting on each of the charged particles generated from the gas in the space.

According to a third aspect of the present invention, there is provided a plasma generating method for converting a gas in a depressurized space into a plasma by magnetron discharge using an electric field and a magnetic field. Applying an electric field to the depressurized space so as to ionize the gas introduced into the depressurized space, and charged particles generated from the gas in the depressurized space in a direction crossing the applied electric field and receiving the Lorentz force, respectively. Applying a magnetic field to the decompressed space so as to drift in directions diverging from each other.

Further, in the plasma generating method according to the present invention, the step of introducing a gas into the reduced pressure space and the step of applying an electric field to the reduced pressure space so as to ionize the gas introduced into the reduced pressure space. And a step of applying a magnetic field to the reduced pressure space in a direction crossing the applied electric field. However, the magnetic field applied in the magnetic field applying step has a gradient in which the magnetic flux density becomes weaker sequentially in the direction of drift of the charged particles due to Lorentz force acting on each of the charged particles generated from the gas in the reduced pressure space. .

[0025]

According to the first to fourth aspects of the present invention, the direction of drift of charged particles in the plasma is not parallel as in the prior art,
It is possible to diverge, and the bias of the plasma can be reduced. That is, since the plasma density is made uniform, charge-up of the material to be processed is reduced, and damage due to static electricity is reduced.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a plasma processing apparatus and a plasma processing method according to an embodiment of the present invention will be described with reference to the drawings.

FIGS. 1 and 2 are principle diagrams of a plasma processing method according to an embodiment of the present invention, and both correspond to FIG. 18 relating to a conventional example.

According to FIG. 1, a magnetic field 12 is applied from the magnetic field applying device 8 so that the directions of lines of magnetic force adjacent to each other on the surface of the workpiece 4 are not parallel to each other. That is, the magnetic field lines of the magnetic field 12 are generated radially from one end (the lower part of the paper surface in FIG. 1) of the workpiece 4. Such a line of magnetic force is obtained when a magnet is placed at the bottom of the drawing.
The magnet has an N pole to the right of the center at the bottom of the page, and an S pole to the left.
There are poles. For this reason, the lines of magnetic force never become parallel on the workpiece 4. Simultaneously with the application of the magnetic field, an electric field (not shown) is applied perpendicular to the plane of the drawing.

The electric field and the magnetic field 12 crossing each other,
Charged particles in the plasma receive Lorentz force. The charged particles that have received the Lorentz force drift in the direction of arrow D while performing cycloidal motion. At this time, the magnetic field 12 is applied such that the drift direction of the charged particles diverges from one end of the workpiece 4 toward the opposite end. Due to this drift, the number of collisions of charged particles increases, the degree of ionization of the processing gas increases, and highly efficient plasma can be obtained. The workpiece 4 is exposed to this plasma, and plasma processing such as etching is performed. In addition, since the direction of drift of the charged particles diverges as shown by arrow D in FIG. 1, the bias of the plasma is reduced as compared with the conventional case (FIG. 18) in which a parallel magnetic field is applied. For this reason, destruction due to charge-up of a semiconductor device or the like can be prevented.

According to FIG. 2, the magnetic field 14 generated by the magnetic field applying device 8 has a line of magnetic force gradually curved from a straight line passing substantially through the center of the workpiece 4 toward both sides of the workpiece 4. doing. A straight line passing substantially through the center of the material to be processed 4 is the left-right direction on the paper surface. Magnet N on right side of paper
When the S pole is placed on the left side of the pole, such a line of magnetic force is formed. For this reason, the direction of drift of the charged particles is, as indicated by arrow D, a direction in which the charged particles located below the center of the workpiece 4 diverge toward the end of the workpiece 4 (upper side of the paper). . However, the magnetic field 14 is applied to the processing chamber 1
Are applied such that the distribution in the inside is symmetrical in the vertical and horizontal directions on the plane of FIG.

Also in this case, the drift direction of the charged particles diverges as shown by the arrow D in FIG. 2, so that the bias of the plasma is smaller than in the conventional case (FIG. 18) in which a parallel magnetic field is applied. Therefore, destruction due to charge-up of a semiconductor device or the like can be prevented. Moreover, the distribution of the magnetic field 14
Is symmetrical in the vertical and horizontal directions with respect to the plane shown in FIG. 1, and when the material to be processed 4 is a disk, the uniformity of the plasma processing can be improved by rotating the direction in which the magnetic field 14 is applied.

Next, a specific example of a magnetron etching apparatus utilizing the above principle will be described. If a magnetic field applying device having the following configuration is employed instead of the magnet 29 in the conventional magnetron etching device 30 shown in FIG.
8 can have a desired gradient (hereinafter, referred to as a magnetic field gradient) in the magnetic field density, that is, the drift direction of the charged particles in the plasma can be diverged, and the plasma density can be made uniform. That is, by placing the wafer A in a space having this magnetic field gradient, charge-up of the surface of the wafer A can be prevented or suppressed as described later in detail.

Hereinafter, eight specific means for forming the magnetic field gradient will be described. However, it is assumed that a high-frequency electric field is applied perpendicular to the surface of the wafer A simultaneously with the application of the magnetic field by each specific means.

FIGS. 3A and 3B show a schematic perspective view and a schematic plan view of a first configuration example of a magnetic field application device for forming a magnetic field gradient. In the first configuration example, a magnet 29 is arranged on the side of the wafer A to form a magnetic field gradient. That is, by disposing the magnet 29 on the side of the processing chamber 21, FIG.
As shown in (b), a magnetic field gradient is formed which becomes weaker in the direction of drift D due to the Lorentz force so as to make the plasma density uniform.

FIGS. 4A and 4B show a schematic plan view and a schematic perspective view of a second configuration example of the magnetic field applying device. In the second configuration example, the N pole and the S pole are positioned obliquely on the left and right sides of the wafer A in the processing chamber 21.
This adopts the configuration of the inner magnet type magnet 29 in which the poles are arranged to face each other. That is, the north pole and the south pole of the magnet 29 also having the similar curved surface are arranged on the inner surface of the side wall of the processing chamber 21 having the curved surface substantially similar to the outer peripheral circle of the wafer A. By arranging the S pole on the side opposite to the direction D of the drift due to the Lorentz force, the plasma density is made uniform.

FIG. 5 is a schematic perspective view of a third configuration example of the magnetic field applying device. This third configuration example uses a magnet 29
Is arranged above the wafer A on the side opposite to the direction D of drift due to Lorentz force, away from the center of the wafer A, thereby forming a magnetic field gradient. By arranging the magnet 29 away from right above the wafer A in this manner, the weak magnetic field 38 can be applied to a portion where the plasma density is high.
a is applied, and conversely, a strong magnetic field 38b is applied to a portion having a low plasma density, so that the plasma density on the surface of the wafer A becomes uniform.

FIG. 6 is a schematic perspective view of a fourth configuration example of the magnetic field applying device. In the fourth configuration example, the magnet 29
The magnetic field gradient is formed by changing the magnetic force of itself. That is, by mounting a plurality of magnetic field control rod magnets 29b having the same and opposite magnetization directions as the magnetization direction of the magnet main body 29a on the upper surface of the magnet main body 29a disposed above the wafer A, The magnetic flux density of the whole 29 has a gradient.
For example, as shown in FIG. 6, on the upper surface of the magnet main body 29a, three bar magnets 29b having a magnetization direction opposite to the magnetization direction of the magnet main body 29a are arranged at an end on the direction D side of the drift due to the Lorentz force. And two bar magnets 29b having the same magnetization direction are arranged next to the three bar magnets,
Two bar magnets 29b having opposite magnetization directions are arranged next to the two bar magnets, and three bar magnets 29b having the same magnetization direction are arranged next to the two bar magnets. Arrange. Thereby, the direction D of the drift due to the Lorentz force
A weak magnetic field 38a is applied to the opposite side, and a strong magnetic field 38b is applied to the opposite side.
Is applied to make the plasma uniform. If the bar magnets 29b whose magnetization directions are opposite to each other with the center of the magnet body 29a as a boundary are arranged, the bar magnets 2
The number of 9b can be arbitrarily selected.

FIG. 7 is a schematic perspective view of a fifth configuration example of the magnetic field applying device. This fifth configuration example uses a magnet 29
Is tilted by a predetermined angle α with respect to the parallel plane of the surface of the wafer A, that is, inclined so as to raise the direction D of drift due to Lorentz force upward, thereby forming a magnetic field gradient. . Thus, magnet 2
By inclining the surface 9 with respect to the parallel surface of the wafer A, a magnetic field distribution convexly curved in the D direction is obtained on the surface of the wafer A. Therefore, the drift direction D of the charged particles diverges on the surface of the wafer A. That is, since the weak magnetic field 38a is applied to the portion where the plasma density is high, and the strong magnetic field 38b is applied to the portion where the plasma density is low, the plasma density on the surface of the wafer A becomes uniform.

FIG. 8 is a schematic perspective view of a sixth configuration example of the magnetic field applying device. In the sixth configuration example, the magnet 29
The magnetic field gradient is formed by changing the volume of itself. That is, the magnet 2 whose thickness is gradually reduced toward the direction D of drift due to Lorentz force
9 is arranged above the wafer A, a weak magnetic field 38a is applied to the drift direction D side, and a strong magnetic field 3a is applied to the opposite side.
8b is applied to make the plasma uniform.

FIGS. 9A and 9B are a schematic plan view of a seventh configuration example of the magnetic field applying device and an explanatory diagram of the magnetic field gradient. In the seventh configuration example, a magnetic field gradient is formed using an electromagnet. That is,
The sub-electromagnets 29d are provided by arranging two pairs of electromagnets 29c in pairs in the four circumferential directions outside the wafer A, and arranging the sub-electromagnets 29d on the back side of the ends of the respective electromagnets 29c. In this case, the magnetic field on the side of the side is strengthened so as to have a magnetic field gradient (see FIG. 9B). In this case, the electromagnet 29c and the sub-electromagnet 29d may be fixed, but by rotating them, the plasma density can be made more uniform.

FIGS. 10A and 10B are schematic plan views of an eighth configuration example of the magnetic field applying device. In the eighth configuration example, a magnetic field gradient is formed using electromagnets as in the seventh configuration example. Electromagnets 29c are arranged in four circumferential directions outside the wafer A, and two adjacent electromagnets are arranged. An electric current in the opposite direction is applied to 29c to form a magnetic field gradient, and the electromagnets 29c are sequentially electrically switched (FIG. 10B).
When two adjacent electromagnets 29c are turned on, the remaining two electromagnets 29c are turned off so that the plasma density becomes uniform.

When the wafer A is placed in the space where the magnetic field gradient is formed as described above, as shown in FIG. 11, the plasma density on the PQ surface of the wafer A and the etching rate (E /
R) and the potential (V _DC ) are substantially uniform, so that charge-up on the surface of the wafer A can be prevented or suppressed. FIG. 14 is a diagram corresponding to FIG. 21 relating to a conventional magnetron etching apparatus in the case of the present embodiment. Further, according to the present embodiment, since the ion sheath is made uniform, the problem that the etched shape is bent to one side can also be solved. As a result, it becomes easy to align the processing shape in the plane of the wafer A not only for an 8-inch wafer but also for a larger diameter in the future.

As described above, according to the magnetron etching apparatus according to the above-described embodiment, when the processing gas is turned into plasma by the magnetron discharge caused by the high-frequency electric field and the magnetic field, the wafer A is etched in a direction crossing the high-frequency electric field. The magnetic field 38 is given a gradient in which the magnetic flux density becomes weaker in the drift direction D due to the Lorentz force. This makes the plasma density uniform, so that the etching process can be made uniform without lowering the etching rate. The magnet 29 is connected to the wafer A
May be provided on the back side, or on both the front side and the back side, and a magnetic field gradient may be formed in the plasma space. Therefore, the position of the wafer A is not limited to the position of the magnet 29, and the position of the wafer A may be changed. That is, the positional relationship between the wafer A and the magnet 29 may be set relatively.

Next, the optimum conditions of the magnetic field distribution in the magnetron etching apparatus will be described. Optimal conditions are
(1) The lines of magnetic force are parallel to and do not intersect with the surface of the wafer A; (2) The magnetic flux densities at the center and the periphery of the wafer A are the same; (3) Due to the Lorentz force That is, the three conditions that the magnetic flux density has a gradient so as to become weaker in the direction of drift of the charged particles are satisfied simultaneously.

FIG. 12 is a schematic front sectional view of a magnetron etching apparatus showing a comparative example, and FIG. 13 shows a case where an optimum condition is satisfied (example). The arrows in both figures indicate the magnetic field 38.
And its length represents the magnitude of the magnetic flux density. The magnetic field 38 in FIG. 12 is almost parallel to the surface near the center of the wafer A, and the magnetic flux density is small.
At the left end of the wafer A, the magnetic flux density is large, but the magnetic field 38 is curved in the divergent direction as the distance from the surface of the wafer A increases. Conversely, on the right side of the wafer A, the magnetic field 38 is curved in the direction of convergence. On the other hand, in FIG.
Are parallel to the surface of the wafer A and are distributed with substantially the same magnetic flux density.

Here, for the component of the magnetic field 38 in the direction (horizontal direction) parallel to the wafer A, the ratio of the magnetic flux density B2 at the peripheral portion to the magnetic flux density B1 at the central portion of the wafer A is represented by R
(= B2 / B1). In FIG. 12, R> 1 and in FIG. 13, R = 1 (minimum value and ideal value).

In a wafer A having, for example, an EEPROM element formed on the surface, the flat band voltage of the element shifts during the etching process due to charge-up of the insulating film. Therefore, the rate at which the flat band voltage shifts outside the range of -0.5 V to +0.5 V due to the change in R, that is, the failure occurrence rate due to charge-up (hereinafter, referred to as
Defect rate. ) Was experimentally investigated. The etching conditions were a pressure of 5 Pa, an applied high-frequency power of 1000 W, and a gas CH.
F ₃ , the gas flow rate is 50 sccm. The magnetic flux density at the center of the wafer A was set to 12 to 24 mT.

As a result of the experiment, when R = 2.4, about 70%
However, when R = 1.85, the defect rate was reduced to about 28%. Further, it can be confirmed that if R is set in the range of about 1.0 to 1.5, it is possible to prevent the charge-up of the wafer A in the direction (N-S direction) between the N pole and the S pole of the two magnets 29. Was. This is because when R approaches 1, not only the magnetic field 38 on the wafer A surface but also the shape of the magnetic field 38 in the plasma discharge space approaches horizontal (see FIG. 13).
This is because uniform plasma is formed.

FIG. 14 is a plan view for explaining the definition of the divergence angle θ with respect to the magnetic field distribution on the surface of the wafer A.
The arrow in the figure indicates the direction of the magnetic field 38, and the length indicates the magnitude of the magnetic flux density. An electric field (not shown) is applied in a direction perpendicular to the paper surface. The direction connecting the two magnets (NS direction) is defined as the x-axis, and the direction perpendicular thereto (E-
W direction) is defined as the y-axis. Assuming that the projected length of the magnetic field 38 acting on the right end of the wafer A on the x axis is Bx and that on the y axis is By, the divergence angle θ = tan ⁻¹ (By /
Bx).

FIG. 15 shows a case where θ <0 (comparative example).
FIG. 6 is a plan view of a magnetic field distribution showing each case where θ> 0 (Example). In FIG. 15, the magnetic field 38 is distributed so as to expand toward the E side (θ <0), and the magnetic flux density increases in the drift directions D0 to D2 of the charged particles due to Lorentz force (that is, from E to W) sequentially. Have such a gradient.
Therefore, the drift directions D0 to D2 tend to converge, and the charge-up amount in the EW direction is larger than in the related art (see FIG. 18). On the other hand, in FIG. 16, the magnetic field 38 is distributed so as to expand toward the W side (θ> 0),
The magnetic flux density has a gradient such that it gradually becomes weaker in the drift directions D0 to D2 of charged particles (that is, from E to W). Therefore, the drift directions D0 to D2 tend to diverge, and the charge-up amount in the EW direction is reduced.

When the θ dependency of the defect rate was examined under the same etching conditions as in the case of the R dependency, the defect rate when θ = 0 was 58%, and worse when θ <0. . On the other hand, if θ = + 3.8 °, the defective rate could be reduced to 5%. Also, θ is about + 1 ° to +
It was confirmed that setting the angle in the range of 89 ° could prevent charge-up of the wafer A in the EW direction.

Although the above embodiment specifically describes the case where the present invention is applied to plasma etching,
The present invention is applicable to all cases where a magnetron plasma is generated. For example, the present invention may be applied to any of a sputtering device, a plasma CVD device, an ion source, an electron beam source, an X-ray source, an ashing device, and the like.

In the above-described embodiment, the gradient of the magnetic field distribution is set. However, by providing the gradient of the electric field distribution,
It is also possible to control the drift direction of charged particles due to Lorentz force. As a result, the same effect as when the magnetic field has a gradient can be obtained.

Although the present invention has been described in detail by way of illustration and example for purposes of clarity of understanding, certain changes and modifications may be made in the claims.

[0055]

As described above, claims 1 to 4 are described.
According to the invention, the configuration in which the electric field and the magnetic field are applied to the plasma space so as to diverge the drift direction of the charged particles in the plasma is adopted, so that the bias of the plasma is reduced,
Damage to the material to be processed due to charge-up can be reduced. When the present invention is applied to, for example, the manufacturing process of a semiconductor device, highly efficient and low-damage plasma processing can be realized, and the yield and reliability of the semiconductor device can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic plan sectional view of a plasma processing apparatus for explaining a magnetic field distribution in a plasma processing method according to an embodiment of the present invention.

FIG. 2 is a view similar to FIG. 1 for explaining another magnetic field distribution in the plasma processing method according to the embodiment of the present invention.

FIG. 3A is a schematic perspective view showing a first configuration example of a magnetic field applying device for forming a magnetic field gradient in a magnetron etching apparatus according to an embodiment of the present invention, and FIG. 3B is a schematic plan view thereof. It is.

FIG. 4A is a schematic plan view showing a second configuration example of the magnetic field applying device, and FIG. 4B is a schematic perspective view thereof.

FIG. 5 is a schematic perspective view showing a third configuration example of the magnetic field application device.

FIG. 6 is a schematic perspective view showing a fourth configuration example of the magnetic field application device.

FIG. 7 is a schematic perspective view showing a fifth configuration example of the magnetic field application device.

FIG. 8 is a schematic perspective view showing a sixth configuration example of the magnetic field application device.

9A is a schematic plan view showing a seventh configuration example of the magnetic field applying device, and FIG. 9B is an explanatory diagram of the magnetic field gradient.

FIG. 10A is a schematic plan view at an instant showing an eighth configuration example of the magnetic field applying device, and FIG. 10B is a similar diagram at another instant.

FIG. 11 is a graph showing a distribution of a plasma density, an etching rate, and a potential in a magnetron etching apparatus according to an example of the present invention.

FIG. 12 is a schematic front sectional view of a magnetron etching apparatus showing a magnetic field distribution in a plasma processing method according to a comparative example of the present invention.

FIG. 13 is a view similar to FIG. 12, showing a magnetic field distribution in the plasma processing method according to the embodiment of the present invention.

FIG. 14 is a plan view for explaining a definition of a divergence angle θ with respect to a magnetic field distribution on a wafer surface.

FIG. 15 is a plan view of a magnetic field distribution in a plasma processing method according to a comparative example of the present invention.

FIG. 16 is a view similar to FIG. 15, illustrating a plasma processing method according to an embodiment of the present invention;

FIG. 17 is a schematic front sectional view of a conventional plasma processing apparatus.

18 is a schematic plan sectional view of the plasma processing apparatus of FIG.

FIG. 19 is a front sectional structural view of a conventional magnetron etching apparatus.

20 is a schematic plan view showing a relationship between a magnetic field and a wafer as a substrate to be processed in the magnetron etching apparatus of FIG. 19;

FIG. 21 is a graph showing distributions of plasma density, etching rate, and potential in the XX section in FIG. 20;

[Explanation of symbols]

 1,21 Processing chamber 2,3,22,23 Electrode 4 Material to be processed 5,32 (High frequency) power supply 8 Magnetic field applying device 9 Electric field 10,12,14,38 Magnetic field 29 Magnet 29a Magnet body 29b Bar magnet 29c Electromagnet 29d Sub Electromagnet 30 Magnetron etching apparatus A Substrate to be processed (semiconductor wafer) D Drift direction of charged particles due to Lorentz force

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Nakagawa 1006 Kazuma Kadoma, Kazuma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (58) Field surveyed (Int.Cl. ⁷ , DB name) H05H 1/46 C23C 16/50 C23F 4/00 H01L 21/3065

Claims (4)

(57) [Claims] 1. A plasma generator for converting a gas in a chamber holding a reduced pressure into a plasma by magnetron discharge using an electric field and a magnetic field, wherein the electric field for ionizing the gas in a space between the two is provided. At least two electrodes installed in the chamber so as to be applied to a space, and charged particles generated from gas in the space in a direction crossing an electric field by the electrodes, and scattered from each other under Lorentz force And a magnetic field applying device for applying a magnetic field to the space so as to drift in a direction. 2. A plasma generator for converting a gas in a chamber holding a reduced pressure into a plasma by magnetron discharge using an electric field and a magnetic field, wherein the electric field for ionizing the gas in a space between each other is provided. At least two electrodes installed in the chamber so as to be applied to a space, and in a direction crossing an electric field by the electrodes, the charged particles generated by the Lorentz force acting on each of the charged particles generated from the gas in the space. A magnetic field applying device for applying a magnetic field having a gradient in which the magnetic flux density becomes weaker in the direction of drift to the space sequentially. 3. A method for generating a plasma in a gas in a reduced-pressure space by magnetron discharge using an electric field and a magnetic field, the method comprising: introducing a gas into the reduced-pressure space; Applying an electric field to the reduced-pressure space so as to ionize the gas, and charged particles generated from the gas in the reduced-pressure space in a direction intersecting with the applied electric field, and diverge from each other under Lorentz force. Applying a magnetic field to the decompressed space so as to drift in a direction in which the plasma is generated. 4. A method for generating a plasma in a gas in a reduced pressure space by magnetron discharge using an electric field and a magnetic field, the method comprising: introducing a gas into the reduced pressure space; Applying an electric field to the decompressed space so as to ionize the gas, and the charged particles due to Lorentz force acting on each of the charged particles generated from the gas in the depressurized space in a direction crossing the applied electric field. Applying a magnetic field having a gradient in which the magnetic flux density becomes weaker in the drift direction sequentially to the decompression space.