JP2879302B2 - Magnetic field generator for magnetron plasma etching - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic field generator for magnetron plasma etching which generates a magnetic field having good uniformity. The magnetic field generator for magnetron plasma etching according to the present invention is suitable for use in magnetron etching performed in the field of electric and electronic devices.

[0002]

2. Description of the Related Art Magnetron etching (dry etching), in which etching is performed using high-density plasma (magnetron plasma) generated by a magnetron, has been widely performed.

FIG. 4 shows an example of a conventional magnetron etching apparatus (a flat-type bipolar discharge etching apparatus).

FIG. 4A is a longitudinal sectional view of a magnetron etching apparatus, and illustrations other than the section are omitted for simplification of the drawing. FIG. 4B is a perspective view in which a part of the magnetron etching apparatus of FIG. 4A is separately illustrated for the sake of convenience, and is a view for explaining the movement of electrons in the magnetron etching apparatus.

A wafer 14 is provided between the parallel plates 10 and 12, and a magnetic field generator 18 for magnetron plasma etching is provided on the back surface of the plate 12. The magnetic field generator 18 for magnetron plasma etching includes:
For example, a disk-shaped permanent magnet 24 is arranged in the hole of the donut-shaped permanent magnet 22, and the upper surfaces of the permanent magnets 22 and 24 are connected by a yoke 26 (FIG. 4).
(See separation diagram in (b)).

The electrode plate 12 is grounded, and a high-frequency voltage is applied to the electrode plate 10. In FIG. 4A, the direction of an electric field generated when the electrode plate 10 becomes a cathode is indicated by an arrow 20.

[0007] The magnetic field lines 28a and 2a
8b (FIG. 4 (a)) or magnetic force line 30 (FIG. 4 (b))
A magnetic field represented by

When performing the magnetron etching, the magnetron etching apparatus shown in FIG. 4 is placed in a container filled with a process gas (usually using a halogen gas). The gas is ionized by the discharge, and the electrons 32 generated at this time are
Due to the action of the electric field in the direction of the arrow 20 and the magnetic field (the component perpendicular to the electric field) represented by the magnetic force lines 30, the endless orbit 34 is drawn while drifting. As a result, the electrons 32 are bound near the surface of the wafer 14 and promote ionization of gas. Then, the newly generated electrons also draw the endless orbit 34, and further ionize the gas. Therefore, the ionization efficiency is very high, and high-density plasma can be generated.

For this reason, the magnetron etching method has an advantage that the efficiency can be obtained two to three times as compared with the normal high pressure discharge method.

However, in the magnetic field generated by the magnetron plasma etching magnetic field generator 18 shown in FIG. 4, a magnetic field component perpendicular to the electric field (a component horizontal to the surface of the wafer 14 in FIG. 4; hereinafter, referred to as a horizontal magnetic field). Does not show a uniform distribution.

FIG. 5 shows this state. Horizontal axis r of graph
Is the distance measured from the origin to the periphery of the wafer along the wafer surface from the origin of the center of the wafer 14, and the vertical axis B represents the horizontal magnetic field intensity at the position of the distance r. From FIG. 5, it can be seen that the horizontal magnetic field intensity varies greatly depending on the location.

In a region where the strength of the horizontal magnetic field is high, ionization of gas is promoted and a high-density plasma is generated. Therefore, quality problems such as intensive etching of a part of the wafer occur. Furthermore, there is also a problem that a non-uniform plasma density causes a potential distribution in the wafer surface (charge-up), thereby destroying the wafer.

In order to solve the above problem, an attempt has been made to use a magnet in which a plurality of anisotropic segment magnets are arranged in a ring shape (hereinafter referred to as a dipole ring magnet) as a magnetic field generator.

FIG. 6 shows a case where an example of a magnetic field generating device comprising a dipole ring magnet is used in a magnetron etching device. FIG. 6A is a plan view (partially omitted) of a magnetron etching apparatus using the above-described magnetic field generator, and FIG.
FIG. 1 shows a cross-sectional view taken along line (illustrations other than the cross-section are omitted for simplification of the drawing).

The dipole ring magnet is cylindrical, and a plurality of anisotropic segmented columnar magnets 40 are mounted on a non-magnetic mount 42.
The structure is stored in The arrow drawn in each columnar magnet 40 indicates the direction of magnetization of each columnar magnet.
By arranging the directions of magnetization as shown in FIG. 6, a magnetic field having a direction indicated by an arrow 43 is generated at the center of the dipole ring magnet.

When used in a magnetron etching apparatus, the plates 36 and 37 are provided inside the dipole ring magnet.
And a wafer 38 are provided as shown in FIG. A high-frequency voltage is applied between the bipolar plates 36 and 37 to generate an electric field in the direction of the symbol 44 (FIG. 6A) or the direction of the arrow 45 (FIG. 6B). By the action of the electric field and the magnetic field in the direction of the arrow 43, the plasma can be generated and bound as in FIG.

At this time, the vicinity of the central section in the length direction of the dipole ring magnet (vertical direction in FIG. 6B) and the plasma generation space 46 (the space for performing etching, which corresponds to the surface of the wafer 14 in FIG. 4). Space)
The position of the wafer 38 is adjusted (see FIG. 6B).

This is because, in principle, only a horizontal magnetic field (magnetic field in the direction of arrow 43) exists at the center of the dipole ring magnet, and the magnetic field uniformity at the center of the dipole ring magnet is better than that of the dipole ring magnet. Is better than the uniformity of the magnetic field at the end. That is, a plasma of uniform density is generated at the center of the dipole ring magnet,
This is because uniform etching is performed.

FIG. 7 shows a horizontal magnetic field generated by the magnetic field generator (FIG. 6) comprising the dipole ring magnet.

FIG. 7 is a graph showing a horizontal magnetic field strength on a straight line CD of a central cross section (a plane including the straight line CD and perpendicular to the length direction of the dipole ring magnet) of the plasma generation space 46. The horizontal axis r of the graph is a distance measured from the origin at the center point 48 of the plasma generation space 46 along the straight line CD in the direction of the straight line CD (the right direction in the figure is defined as positive).
The vertical axis B represents the intensity of the horizontal magnetic field (the magnetic field in the direction of the arrow 43 (FIG. 6)) at the position of the distance r. Also,
L is the size of the radius of the plasma generation space 46.

According to the graph of FIG. 7, the uniformity of the horizontal magnetic field intensity by the magnetic field generator (FIG. 6) composed of the dipole ring magnet is the same as the horizontal magnetic field generated by the conventional magnetic field generator (plane type two-pole discharge sputtering apparatus (FIG. 4)). It can be seen that the magnetic field strength is much better than the uniformity (FIG. 5).

However, in order to sufficiently improve the magnetic field uniformity, it is necessary to increase the length of the dipole ring magnet (RL in FIG. 6). However, when used in a magnetron etching apparatus, it is desired to reduce the size of the dipole ring magnet. FIG. 8 shows an overall view of an apparatus for performing magnetron etching, and the necessity of miniaturization will be described.

In the magnetron etching, an etching chamber (A) incorporating a magnetron etching apparatus, a cassette chamber (B) on which a wafer is mounted, and a wafer in the cassette chamber (B) are transported to the etching chamber (A). This is performed by an apparatus including a load lock chamber (C) provided with an arm.

Each chamber is connected by a passage provided with a valve 49. One of the plurality of wafers 50 placed in the cassette chamber (B) is transferred to the etching chamber (A) by the transfer arm 54 of the load lock chamber (C). After the transported wafer 52 is placed on the electrode plate 56 in the etching chamber (A), the sample table 58 integrated with the electrode plate 56 is moved to an etching position (a position drawn by a broken line) 60. The electric field generated by the electrode plates 56 and 62 and the magnetic field generated by the magnetic field generator 64 generate and restrict the magnetron plasma for etching. At this time, the process gas is injected in the direction of arrow 66 and exhaust is performed in the direction of arrow 68.

Therefore, if the dipole ring magnet used in the magnetron etching apparatus is long, the moving distance of the sample stage 58 to the etching position 60 becomes long. That is, there is a problem that the etching chamber needs to be enlarged, and a large moving distance of the sample stage requires a large amount of driving energy, thereby increasing the manufacturing and operating costs.

Therefore, the length R of the dipole ring magnet
Since L cannot be made too long, there has conventionally been a problem that the uniformity of the magnetic field in the plasma generation space 46 cannot be made very good.

Therefore, when incorporated in a magnetron etching apparatus, a magnetic field generator composed of a dipole ring magnet can obtain a desired horizontal magnetic field uniformity without increasing the size of the etching chamber or increasing the moving distance of the sample stage. Is desired.

[0028]

SUMMARY OF THE INVENTION It is an object of the present invention to obtain a desired uniformity of a horizontal magnetic field without increasing the size of an etching chamber or increasing the moving distance of a sample stage when the magnet is incorporated in a magnetron etching apparatus. It is an object of the present invention to provide a magnetron plasma etching magnetic field generator comprising a dipole ring magnet.

[0029]

In a magnetic field generator for magnetron plasma etching comprising a dipole ring magnet in which a plurality of anisotropic segment columnar magnets are arranged in a ring shape, a part of the plurality of anisotropic segment columnar magnets is provided. An anisotropic segment magnet whose magnetization direction is the axial direction of the anisotropic segment columnar magnet is provided on all or a part of the side surfaces of the plurality of anisotropic segment columnar magnets.

[0030]

FIG. 1 shows an example of a magnetic field generator for magnetron plasma etching according to the present invention, which is an improvement of the magnetic field generator (FIG. 6) comprising the above-mentioned dipole ring magnet. FIG. 1A is a plan view of a magnetron plasma etching magnetic field generator according to the present invention, and FIG. 1B is a cross-sectional view taken along a cutting line EF of FIG. Are omitted to simplify the drawing).

When the magnetic field generator according to the present invention is used for magnetron etching, an electrode plate or the like is provided in the magnetic field generator as in the conventional example shown in FIG. For simplicity,
FIG. 1 omits illustration of the electrode plate and the like.

The dipole ring magnet (FIG. 1) used in the magnetic field generator for magnetron plasma etching according to the present invention includes a plurality of anisotropic segment columnar magnets 70 (1) to 70 (1).
70 (16) is housed in a non-magnetic gantry 72.
Arrows drawn in the respective columnar magnets indicate the directions of magnetization of the respective columnar magnets. By arranging the direction of magnetization as shown in FIG. 1, a magnetic field having a direction indicated by an arrow 73 is generated at the center of the dipole ring magnet.

The number of columnar magnets is eight or more, and is usually selected from eight to thirty-two. FIG. 1 shows a case where 16 columnar magnets are provided. Also, the cross-sectional shape of the columnar magnet (FIG. 1)
The shape shown in (a) is arbitrary, and may be, for example, a cross-section such as a circle or a rectangle. However, FIG. 1 illustrates a case of a square cross-section where manufacturing cost is low.

A feature of the present invention is that the plurality of columnar magnets 70
An anisotropic segment magnet 74 whose magnetization direction is the axial direction of the anisotropic segment columnar magnet is provided on all or a part of the side surfaces of the plurality of columnar magnets, which is a part of (1) to 70 (16). It is in the point provided.

FIG. 1 shows the plurality of columnar magnets 70 (1).
To a columnar magnet 70 (16), which is a part of
70 (1), 70 (2), 70 (8), 70
On one side of each of (9) and 70 (10), anisotropic segment magnets 74 (16), 74 (1), 74 (2) and 74 (8), 74 (9), 74 (10) ) Is provided.

As shown in FIG. 1A, each of the anisotropic segment magnets 74 (16), 74 (1), 74 (2) and 74 (8), 74 (9), 74 (10) The magnetization direction of () is the axial direction of the columnar magnet 70, and their directions are denoted by reference numerals 76 (16), 76 (1), 76 (2), and 76, respectively.
(8), 76 (9) and 76 (10). This is shown by arrows 78 (1) and 78 in FIG.
(9).

With reference to FIG. 2, the difference in the state of the generated magnetic field between the conventional magnetic field generator (FIG. 6) and the magnetic field generator according to the present invention (FIG. 1) will be described.

FIG. 2A shows the state of a magnetic field generated by a conventional magnetic field generator (FIG. 6) comprising a dipole ring magnet in the same sectional view (partially omitted) as FIG. 6B. FIG. The broken line is the magnetic force line 82, and the magnetic force line 82
Indicate the direction of the magnetic force lines 82.

FIG. 2 (b) shows a magnetic field generated by a magnetic field generator (FIG. 1) comprising a dipole ring magnet according to the present invention in the same sectional view as FIG. 1 (b). (Omitted). The broken line is the line of magnetic force 84, and the arrow drawn on the line of magnetic force 84 indicates the direction of the line of magnetic force 84.

As can be seen from FIG. 2 (a), in the conventional magnetic field generator (FIG. 6), the magnetic field is horizontal near the central section in the length direction of the dipole ring magnet. Therefore, conventionally, etching is performed by adjusting the position of a wafer (not shown) so that the plasma generation space 80 (see FIG. 1) coincides with the vicinity of the central section in the length direction of the dipole ring magnet.

On the other hand, FIG. 2B shows that in the magnetic field generator (FIG. 1) according to the present invention, the magnetic field generated near the lower end face of the dipole ring magnet is horizontal. This is because the magnetic field generated by the dipole ring magnet is corrected by the magnetic field generated by the anisotropic segment magnet 74 (the direction of magnetization is indicated by an arrow 78).

Therefore, the plasma generation space 80 may be made to coincide not with the vicinity of the central section in the length direction of the dipole ring magnet but with the vicinity of the lower end surface of the dipole ring magnet. Therefore, in the etching chamber of FIG. 8, the etching position 60 may be lower. That is, the sample stage 58
Can be shortened, and accordingly the etching chamber can be made smaller.

Moreover, in the magnetic field generator according to the present invention (FIG. 1), the uniformity of the horizontal magnetic field generated near the lower end face of the dipole ring magnet is better than that of the conventional magnetic field generator (FIG. 6). .

In FIG. 3, a conventional magnetic field generator (FIG. 6)
And the magnetic field generator according to the present invention (FIG. 1) will be compared, and the above points will be described. FIG. 3A shows a conventional magnetic field generator in which the length RL1 is short so that it can be incorporated into an etching chamber, and the distance between the lower end surface and the portion serving as the plasma generation space 46 (central cross section) is L1. On the other hand, FIG.
(B) is a magnetic field generator according to the present invention, wherein the length RL2 is long (RL2> RL1), and the lower end face and the plasma generation space 80
This is an apparatus in which the distance to a portion (a portion near the lower end surface) is L2.

Here, when L1 = L2, the uniformity of the horizontal magnetic field generated in the plasma generation space 80 by the magnetic field generator according to the present invention is better. That is, when the moving distance of the sample stage is kept equal to that of the related art, the use of the magnetic field generator according to the present invention can improve the uniformity of the horizontal magnetic field at the etching position as compared with the related art.

However, the magnetic field generated by the magnetron plasma etching magnetic field generator (FIG. 1) according to the present invention is different from the donut-shaped magnetic field generated by the conventional magnetron plasma etching magnetic field generator (FIG. 4).
A horizontal magnetic field in only one direction. Therefore, the electrons move in one direction by drifting and do not draw an infinite orbit. However, by rotating the dipole ring magnet along its circumference or using a high frequency power supply as the applied power supply,
You can change the direction of the drift motion of the electron and draw an endless orbit.

[0047]

According to the magnetic field generator for magnetron plasma etching according to the present invention, a desired horizontal position can be obtained without increasing the size of the etching chamber or increasing the moving distance of the sample stage when incorporating the magnetron plasma etching apparatus. Magnetic field uniformity could be obtained.

[Brief description of the drawings]

FIG. 1 is a view for explaining a magnetic field generator for magnetron plasma etching according to the present invention.

FIG. 2 is a view showing a state of a horizontal magnetic field generated in a magnetron plasma etching magnetic field generator (FIG. 1) according to the present invention.

FIG. 3 is a diagram for comparing a conventional magnetic field generator for magnetron plasma etching (FIG. 6) with a magnetic field generator for magnetron plasma etching according to the present invention (FIG. 1).

FIG. 4 is a view for explaining a magnetron etching apparatus (a flat-type bipolar discharge etching apparatus) using a conventional magnetron plasma etching magnetic field generator.

FIG. 5 is a diagram showing a distribution of a horizontal magnetic field intensity generated in a conventional magnetron plasma etching magnetic field generator (FIG. 4).

FIG. 6 is a view for explaining a conventional magnetic field generator for magnetron plasma etching using a dipole ring magnet.

FIG. 7 is a diagram showing a distribution of a horizontal magnetic field intensity generated in a conventional magnetic field generator for magnetron plasma etching using a dipole ring magnet (FIG. 6).

FIG. 8 is a diagram illustrating an entire apparatus for performing magnetron etching.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ identification code FI H01L 21/31 H01L 21/302 C (58) Field surveyed (Int.Cl. ⁶ , DB name) H05H 1/46 C23C 14 / 35 C23F 4/00 H01L 21/203 H01L 21/3065 H01L 21/31

Claims (1)

(57) [Claims] 1. A magnetron plasma etching magnetic field generation device comprising a dipole ring magnet in which a plurality of anisotropic segment columnar magnets are arranged in a ring shape, wherein the magnetron generator is a part of the plurality of anisotropic segment columnar magnets.
A magnetron plasma, wherein an anisotropic segment magnet whose magnetization direction is the axial direction of the anisotropic segment columnar magnet is provided on all or a part of the side surfaces of the plurality of anisotropic segment columnar magnets. Magnetic field generator for etching.