JPH06290897A - Plasma generating device - Google Patents

Abstract

PURPOSE:To maintain the uniformity at a high etching rate while dispersion in the plasma distribution is lessened, and prevent the plasma generating device from being damaged, by installing a pair of main magnetic poles confronting in the direction perpendicular to the electric field on the outside of an etching chamber, and also installing a pair of aux. magnetic poles oppositely situated in the direction perpendicular to the first named direction of confronting. CONSTITUTION:In an etching chamber 1, a counter-electrode 5b is installed confronting an electrode 5a, and an electric field is applied perpendicularly to the plane of this description. In a plasma generating device, an iron core 11 and a plurality of coils 14,... wound on the core are arranged so that the main magnetic poles 12, 13 of a main electric magnet 10 are opposed while the chamber 1 is interposed. On both outer sides of this chamber 1, aux. magnets 15, 16 are arranged perpendicular to the confronting direction of the main magnetic poles 12, 13. The magnets 15, 16 are composed of iron cores 17, 18 having aux. magnetic poles 21, 22 and coils 19, 20 wound thereon. When current is fed to the coil 14 of the magnet 10 and coils 19, 20 of the magnets 15, 16, the magnetic poles 21, 22 become S-pole to the N-pole of the magnetic pole 12, to become N-pole apparently relative to the S-pole of the magnetic pole 13, and the line of magnetic force from the magnetic pole 12 enters to the magnetic pole 13 and the ones 21, 22, and also the lines of magnetic force from the magnetic poles 21, 22 enter to the magnetic pole 13. As a result, the lines of magnetic force are free from risk of widening and can well be controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma generator for generating plasma in a high vacuum and performing dry etching by sputtering or a chemical reaction used together therewith, and more particularly to a plasma generator utilizing magnetic lines of force. Regarding

[0002]

2. Description of the Related Art An etching apparatus for generating plasma in a high vacuum and performing dry etching by sputtering or a chemical reaction used in combination with the plasma, densifies the plasma with magnetic lines of force under a high vacuum to obtain a high etching rate. There is a thing that enables the etching of.

In a concrete parallel plate type plasma etching apparatus, as shown in FIG. 10, a pair of electromagnets (or permanent magnets) 2 and 3 are arranged so as to face each other outside the etching chamber 1. The electromagnet 2 on the left side of the figure is the N pole, and the electromagnet 3 on the right side of the figure is the S pole.
The magnetic lines of force are applied to the magnetic field as shown by the solid line in FIG. In addition, an electric field is applied in the direction perpendicular to the paper surface. As a result, the electrons in the electric field of the plasma generated in the etching chamber 1 travel in a direction perpendicular to the electric field and perpendicular to the lines of magnetic force, as shown by the broken line in FIG. As a result, the plasma density becomes dense in the upper part of FIG. 10, and becomes sparse in the lower part of FIG. Therefore, during etching, the electrode 5a
On the (wafer 4), the portion indicated by the symbol a in FIG. 10 has a higher etching rate than the portion indicated by the symbol b,
By rotating the wafer 4 or reversing the direction of the magnetic field, the wafer 4 as a whole can be etched at a high etching rate.

[0004]

However, as shown in FIG.
As shown in, since the magnetic field lines are spread on the surface of the electrode 5a (wafer 4), the electrons in the electric field of the plasma try to travel in the direction perpendicular to the magnetic field lines.
As shown by the broken lines c and d, the light travels in a lateral direction, and as a result, there are two electron traveling directions in the electric field. As a result, the plasma has various distributions on the surface of the electrode 5a (wafer 4), and the plasma distribution varies. That is, there appears a locally different plasma density. Therefore, there is a problem that the uniformity of the etching rate may deteriorate.

Further, there are various conventional devices for applying a magnetic field to plasma, but the weight of the device itself is large, the divergent magnetic field is large, and the structure of the device is complicated, which makes it difficult to realize the device. There was also the problem of being there.

The object of the present invention has been made in view of the above-mentioned circumstances, and it is possible to reduce the variation of the plasma distribution to maintain the uniformity of the etching rate at a high rate and to prevent the damage of the device. Less,
An object of the present invention is to provide a plasma generator in which the weight of the device itself is small, the divergent magnetic field is small, and the structure of the device is simple.

[0007]

In order to achieve this object, the first aspect of the present invention is that, when plasma is generated in a high vacuum and dry etching is performed by sputtering or a chemical reaction, the plasma has a high density due to magnetic lines of force. In a plasma generating device, the main magnet having a pair of main magnetic poles arranged outside the etching chamber in a direction perpendicular to the electric field and facing each other in a direction substantially perpendicular to the facing direction of the pair of main magnets. And a magnet having a pair of auxiliary magnetic poles arranged outside the etching chamber.

According to claim 2 of the present invention, one main magnet receives a magnetic force line from the other main magnet and a pair of auxiliary magnets, and the other main magnet receives a magnetic force line from the one main magnet and a pair of auxiliary magnets. It is characterized by further comprising control means for controlling the main magnet and the auxiliary magnet so as to switch between the case of receiving and the case of receiving.

Further, according to a third aspect of the present invention, in a plasma generator for densifying plasma by magnetic lines of force when plasma is generated in a high vacuum to perform dry etching by sputtering or chemical reaction, outside the etching chamber. A loop-shaped iron core arranged so as to surround the circumference and first to fourth loop-shaped iron cores which are arranged outside the etching chamber so as to face each other in a direction perpendicular to the electric field and are formed in the loop-shaped iron core.
Magnetic poles and first to fourth coils wound around a loop-shaped iron core between each of the first to fourth magnetic poles.

Further, according to a fourth aspect of the present invention, among the first to fourth magnetic poles, the first to fourth magnetic poles are sequentially switched so that any one of the magnetic poles receives a magnetic force line from the remaining three magnetic poles. It is characterized in that it further comprises control means for the first to fourth coils.

[0011]

According to the first aspect of the present invention, the pair of main magnetic poles are arranged to face each other, and the pair of auxiliary magnetic poles are arranged to face each other in a direction substantially perpendicular to the facing direction of the pair of main magnetic poles. There is. Therefore, when one main magnetic pole receives a magnetic force line from the other main magnetic pole and a pair of auxiliary magnetic poles, the magnetic force line does not spread in the electric field (in the parallel plate electrode) as in the conventional case, and the magnetic force line does not spread. It can be controlled arbitrarily. Therefore, the electrons in the electric field of the plasma are
Since the vehicle travels in one direction, it cannot be divided into two directions as in the conventional case. As a result, the plasma is densely collected with a gentle inclination in the traveling direction of the electrons in the electric field, but the variation in the plasma distribution is reduced. That is, it is possible to effectively prevent the plasma density from being locally different. As a result, the etching rate on the object to be processed can be made uniform. Further, since the plasma distribution is gentle, it is also effective in reducing damage to the object to be processed.

In the second aspect, the magnetic field directions are switched in two ways. Thereby, the traveling direction of the electrons in the electric field is switched, and the plasma densely collected in the traveling direction of the electrons in the electric field can be uniformly distributed on the object to be processed. The uniformity of the etching rate is further improved.

Further, according to a third aspect of the present invention, the loop-shaped iron core arranged so as to surround the outer periphery of the etching chamber is provided with the first to fourth magnetic poles arranged to face each other outside the etching chamber. The first to fourth coils are wound around the loop-shaped iron core at predetermined positions. Therefore, the variation in the plasma distribution is reduced, that is, while effectively preventing the plasma density from being locally different, that is, while making the etching rate of the object to be processed uniform,
The weight of the device itself is light, the divergent magnetic field is small, and the structure of the device can be simplified.

Further, in claim 4, the magnetic field direction is switched to four ways. As a result, the distribution of plasma on the object to be processed can be made more uniform than in the case of claim 2.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A plasma generator according to an embodiment of the present invention will be described below with reference to the drawings.

First, a plasma generator according to a first embodiment of the present invention will be described with reference to FIGS. Figure 1
1 is a schematic plan sectional view of a plasma generator according to a first embodiment of the present invention, FIG. 2 is a schematic front sectional view of the plasma generator shown in FIG. 1, and FIG. It is a typical side view of the plasma generator shown. The same members as those of the related art are designated by the same reference numerals.

As shown in FIGS. 1 to 3, in the etching chamber 1, an object to be processed 4 and an electrode 5a are arranged.
A counter electrode 5b is arranged so as to face the electrode 5a.
As a result, an electric field is applied perpendicularly to the paper surface. A main electromagnet 10 is arranged in the plasma generator so as to straddle the etching chamber 1. This main electromagnet 10
Is an iron core 11 extending over the etching chamber 1 and extended so that the main magnetic poles 12 and 13 are located on both sides of the etching chamber 1, and a plurality of coils 14 wound around the iron core 11. , 14 ... Main pole 1
2 and 13 are arranged to face each other.

Further, in this embodiment, the pair of auxiliary electromagnets 1 are arranged so as to face each other on both outer sides of the etching chamber 1.
5, 16 are arranged. These auxiliary electromagnets 15,
16 is an iron core 17 having auxiliary magnetic poles 21 and 22, respectively.
18 and coils 19 and 20 wound around this.

The main electromagnet 10 and the auxiliary electromagnets 15 and 16 thus constructed are controlled by a control means (not shown).
It is configured to control the current applied to them.

First, the case where each magnetic pole is as shown in FIG. 1 will be described. Main pole 12 and main pole 13
Each have an N pole and an S pole when a current is passed through the coil 14 of the main electromagnet 10. On the other hand, the auxiliary magnet 1
A current is caused to flow through the coils 19 and 20 of the coils 5 and 16, and the intensity of the current is adjusted, whereby the auxiliary magnetic poles 21 and 22 are
Has an S pole with respect to the N pole of the main magnetic pole 12, but has an apparent N pole with respect to the S pole of the main magnetic pole 13. As a result, as shown by the solid line in FIG. 1, the magnetic force lines from the main magnetic pole 12 are received by the main magnetic pole 13 and the auxiliary magnetic poles 21 and 22, and the magnetic force lines from the auxiliary magnets 21 and 22 are also received by the main magnetic pole 13. As a result, the lines of magnetic force do not spread in the electric field as in the conventional case, and the lines of magnetic force can be controlled arbitrarily. Therefore, the electrons in the electric field of plasma proceed in one direction in the electric field as shown by the broken line in FIG. 1, and are not divided into two directions as in the conventional case. As a result, the plasma is densely gathered with a gentle slope in the traveling direction of the electrons in the electric field (ie,
Plasma is collected in the upper part of FIG. 1), but there is less variation in plasma distribution. That is, it is possible to effectively prevent the plasma density from being locally different. Therefore, the etching rate in the electric field can be made uniform. Further, since the plasma distribution is gentle, it is also effective in reducing damage to the wafer 4.

Next, the case where the direction of the current to the main electromagnet 10 is switched and each magnetic pole is as shown in FIG. 4 will be described. In this case, the main magnetic pole 13 takes the N pole,
The main pole 12 takes the S pole, and the currents to the coils 19 and 20 of the auxiliary magnets 15 and 16 are adjusted to adjust the auxiliary poles 21 and 22.
Has an S pole with respect to the N pole of the main magnetic pole 13, but has an apparent N pole with respect to the S pole of the main magnetic pole 12. Also in this case, as shown by the solid line in FIG. 4, the magnetic force lines from the main magnetic pole 13 are received by the main magnetic pole 12 and the auxiliary magnetic poles 21 and 22, and the magnetic force lines from the auxiliary magnets 21 and 22 are also received.
Accepted by. As a result, in the electric field, the magnetic force lines are densely gathered, and the electrons in the electric field of the plasma travel in one direction in the electric field, as shown by the broken line in FIG. Although the electrons are densely collected with a gentle inclination in the traveling direction of the electrons (that is, the plasma is collected in the lower part of FIG. 4), the variation in the plasma distribution is small, and therefore the etching rate on the wafer 4 is made uniform. be able to.

Further, as described above, by switching between the case of FIG. 1 and the case of FIG. 4 in two ways, the place where the plasma is densely gathered is from above (in the case of FIG. 1) to below (in the case of FIG. 4). The plasma can be switched to
It can be uniformly distributed in the electric field, and the uniformity of the etching rate can be further improved.

The auxiliary electromagnets 15 and 16 may be permanent magnets. Further, the auxiliary magnetic poles 21 and 22 of the auxiliary electromagnets 15 and 16 may be fixed to either the N pole or the S pole.
1, 22 may be inverted.

Next, a plasma generator according to a second embodiment of the present invention will be described with reference to FIGS. 5 is a schematic plan sectional view of a plasma generator according to a second embodiment of the present invention, and FIG. 6 is a schematic side sectional view of the plasma generator shown in FIG.

In the etching chamber 1, an object 4 to be processed and an electrode 5a are arranged, and a counter electrode 5b is arranged so as to face the electrode 5a. As a result, an electric field is applied perpendicularly to the paper surface. In the present embodiment, the loop-shaped iron core 30 is arranged so as to surround the four side surfaces of the etching chamber 1.
Is provided. From the loop-shaped iron core 30, first to fourth magnetic poles 31, 32, 33, 34 are projected so as to face each side surface of the etching chamber 1. First to fourth coils 35, 36, 37, 38 are wound around the corners of the loop core 30 between the first to fourth magnetic poles 31, 32, 33, 34. ing.
These first to fourth coils 35, 36, 37, 38
Are independent of each other, and the direction and magnitude of the current can be adjusted individually, and the magnetic field lines formed by these coils are the same as those in the first embodiment.

Next, the operation will be described.

The first to fourth coils 35, 36, 37,
As the current to be passed through 38, the first coil 35 and the fourth coil 38 are set in the same current direction, and the second coil 36 and the third coil 37 are set in the same current direction. The first coil 35 and the second coil 36 have the same current strength, the third coil 37 and the fourth coil 38 have the same current strength, and further, the current strength of the first coil 35 is the same. Is set to be smaller than the current intensity of the fourth coil 37.

As a result, the third magnetic pole 33 apparently takes the N pole, and the second and fourth magnetic poles 32 and 34 become the S pole with respect to the third magnetic pole, but the apparent N pole. And the first magnetic pole 31 has an S pole. Therefore, in the etching chamber 1, as shown by the solid line in FIG.
From the first, second, and fourth magnetic poles 31, 3
2, 34, and second and fourth magnetic poles 32, 3
The magnetic field lines from No. 4 are received by the first magnetic pole 31.
As a result, in the electric field, the magnetic force lines do not spread as in the conventional case, and the magnetic force lines are densely gathered. Therefore, the electrons in the electric field of the plasma move in one direction in the electric field as shown by the broken line in FIG. 5, and the plasma is densely collected with a gentle inclination in the traveling direction of the electrons in the electric field. Although the plasma is collected (that is, the plasma is collected in the upper right part of FIG. 5), the variation in the plasma distribution is reduced, so that the etching rate on the wafer 4 can be made uniform. Further, since the plasma distribution is gentle, it is also effective in reducing damage to the wafer 4.

Next, the first to fourth coils 35, 36,
By switching the strength and direction of the current flowing to 37 and 38,
The fourth magnetic poles 31, 32, 33, and 34 have N and S poles as shown in FIG. In this case, the fourth magnetic pole 34 is an S pole, and the magnetic force lines are collected on the fourth magnetic pole 34, so that the plasma is densely collected in the upper left part of FIG. 7 and the plasma distribution has variations. The number of wafers is reduced, and the etching rate on the wafer 4 can be made uniform.

Similarly, the first to fourth coils 35, 3
Switching the strength and direction of the current flowing through 6, 37, 38,
The first to fourth magnetic poles 31, 32, 33, and 34 have N and S poles as shown in FIG. In this case, the third magnetic pole 33 is an S pole, and the third magnetic pole 33 is
Since the magnetic lines of force are concentrated on the lower part of FIG. 8, the plasma is densely concentrated on the lower left side of FIG. 8 and the variation in the plasma distribution is reduced, so that the etching rate on the wafer 4 can be made uniform.

Further, similarly, the first to fourth coils 3
The strengths and directions of the currents to be passed through 5, 36, 37 and 38 are switched so that the first to fourth magnetic poles 31, 32, 33 and 34 have N and S poles as shown in FIG. In this case, the second magnetic pole 32 is the S pole, and the magnetic force lines are collected on the second magnetic pole 32, so that the plasma is densely collected in the lower right part of FIG. 9 and the plasma distribution has a variation. The number of wafers is reduced, and the etching rate on the wafer 4 can be made uniform.

As described above, by switching the magnetic field directions in four ways, the places where plasma is densely collected are located in the upper right (in the case of FIG. 5), the upper left (in the case of FIG. 7), and the lower left (in the case of FIG. 8).
In this case), the lower right side (in the case of FIG. 9) can be switched, whereby the plasma can be uniformly distributed as a total in the electric field, and the uniformity of the etching rate can be further improved.

Further, the plasma generator of this embodiment is
Since the iron core 30 has a loop shape, the total weight of the iron core can be reduced as compared with the case of the first embodiment, the shape thereof is compact, and the device can be easily made. Further, since the iron core 30 has a loop shape and the first to fourth coils 35, 36, 37, 38 are distributed winding, the divergent magnetic field to the outside can be reduced. .

The present invention is not limited to the above-mentioned embodiments, and can be variously modified.

[0035]

As described above, according to the first aspect of the present invention, the magnetic force lines do not have a spread, and the magnetic force lines can be arbitrarily controlled. Therefore, the electrons in the electric field of the plasma relatively move in one direction in the electric field, and as a result, the plasma is densely gathered with a gentle inclination in the traveling direction of the electrons in the electric field. That is, it is possible to effectively prevent the plasma density from being locally different. As a result, the etching rate on the object to be processed can be made uniform. Further, since the plasma distribution is gentle, it is also effective in reducing damage to the object to be processed.

In the second aspect, the magnetic field directions are switched in two ways. As a result, the traveling direction of the electrons in the electric field is switched, and the plasma densely gathered in the traveling direction of the electrons in the electric field can consequently be uniformly distributed in the electric field. The uniformity of the etching rate is further improved.

Further, in claim 3, the loop-shaped iron core arranged so as to surround the outer periphery of the etching chamber is formed with the first to fourth magnetic poles arranged to face each other outside the etching chamber. The first to fourth coils are wound around the loop-shaped iron core at predetermined positions. Therefore, the variation in the plasma distribution is reduced, that is, while effectively preventing the plasma density from being locally different, that is, while making the etching rate of the object to be processed uniform,
The weight of the device itself is light, the divergent magnetic field is small, and the structure of the device can be simplified.

Further, in claim 4, the magnetic field direction is switched to four ways. As a result, the distribution of plasma on the object to be processed can be made more uniform than in the case of claim 2.

[Brief description of drawings]

FIG. 1 is a schematic plan sectional view of a plasma generator according to a first embodiment of the present invention.

FIG. 2 is a schematic front sectional view of the plasma generator shown in FIG.

FIG. 3 is a schematic side view of the plasma generator shown in FIG.

FIG. 4 is a schematic plan sectional view of the plasma generator shown in FIG. 1, showing a case where a current to a coil is switched.

FIG. 5 is a schematic plan sectional view of a plasma generator according to a second embodiment of the present invention.

6 is a schematic side sectional view of the plasma generator shown in FIG.

7 is a schematic plan cross-sectional view of the plasma generator shown in FIG. 5, showing a case where the current to the coil is switched.

8 is a schematic plan cross-sectional view of the plasma generator shown in FIG. 5, showing a case where the current to the coil is switched.

9 is a schematic plan sectional view of the plasma generator shown in FIG. 5, showing a case where the current to the coil is switched.

FIG. 10 is a schematic plan sectional view of a conventional plasma generator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 etching chamber 10 main electromagnet (main magnet) 12 main magnetic pole 13 main magnetic pole 15 auxiliary electromagnet (auxiliary magnet) 16 auxiliary electromagnet (auxiliary magnet) 21 auxiliary magnetic pole 22 auxiliary magnetic pole 30 looped core 31 first magnetic pole 32 second magnetic pole 33 3rd magnetic pole 34 4th magnetic pole 35 1st coil 36 2nd coil 37 3rd coil 38 4th coil

Claims (4)

[Claims] 1. A plasma generator that densifies plasma by magnetic lines when plasma is generated in a high vacuum and dry etching is performed by sputtering or chemical reaction. A main magnet having a pair of main magnetic poles arranged to face each other, and a magnet having a pair of auxiliary magnetic poles arranged outside the etching chamber so as to face each other in a direction substantially perpendicular to the facing direction of the pair of main magnets. A plasma generator comprising: 2. A method for switching between a case where one main magnet receives a magnetic force line from the other main magnet and a pair of auxiliary magnets and a case where the other main magnet receives a magnetic force line from one main magnet and a pair of auxiliary magnets. The control means for controlling the main magnet and the auxiliary magnet is further provided.
The plasma generator described in 1. 3. A plasma generator that densifies plasma by magnetic lines when plasma is generated in a high vacuum and dry etching is performed by sputtering or chemical reaction, and is arranged so as to surround the outer periphery of the etching chamber. A loop-shaped iron core, first to fourth magnetic poles formed on the loop-shaped iron core, which are arranged to face each other outside the etching chamber in a direction perpendicular to the electric field, and the first to fourth magnetic poles. And a first to a fourth coil wound around a loop-shaped iron core between the respective plasma generators. 4. A first to a fourth coil for sequentially switching the first to fourth magnetic poles so that any one of the first to fourth magnetic poles receives a magnetic force line from the remaining three magnetic poles. The plasma generator according to claim 3, further comprising control means.