JPS6321833A - Dry etching apparatus - Google Patents

Abstract

PURPOSE:To prevent ions from being bent due to a magnetic field and to prevent the working shape of an orthogonal pattern from being differentiated by disposing the locating position of first magnetic field applying means at the rear side of an electrode opposed to an electrode which places a substrate to be etched. CONSTITUTION:First magnetic field generators 19 aligned in the order of NSNS of permanent magnets 19a are disposed near on the upper surface of a second electrode 12 out of a vessel 10, a predetermined magnetic field is formed between the first and second electrodes 11 and 12 through the electrode 12, and reciprocated in a direction of an arrow P along the electrode 12 by a moving mechanism 20. A second magnetic field generator 21 made of a plurality of permanent magnets 21a is disposed at the position opposed to the sidewall of the vessel 10 out of the vessel 10. The generator 21 has the magnets 21 in the order of NSNS on the same circumference at an equal interval and supplies a magnetic field of direction perpendicular to the opposing directions of the electrodes 11, 12 between the electrodes 11 and 12. Thus, incident ions are prevented from being bent due to the magnetic field, and a phenomenon that the working shape of an orthogonal pattern is different can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a dry etching apparatus, and particularly to a dry etching apparatus using magnetron discharge.

(Prior Art) In recent years, reactive ion etching technology has been mainly used for microfabrication for manufacturing highly integrated devices. In the reactive ion etching method, a substrate to be etched is placed on one electrode in a vacuum chamber having a pair of opposing electrodes, a gas containing halogen atoms such as CF4 is introduced into the chamber, and the above-mentioned This is a method in which high-frequency power is applied between a pair of electrodes to discharge gas, and the generated ions and radicals are used to etch the substrate to be etched.

Etching apparatuses using the above method include a batch-type apparatus in which, for example, 10 to 20 substrates to be etched are placed in a large chamber at a time, and a batch type apparatus in which only one substrate to be etched is placed in a small chamber. There is a single-wafer type device that performs etching. In the future, the dimensions of LSI will continue to become smaller and the S1 wafer diameter will continue to increase to 8 inches or 12 inches. Therefore, in order to uniformly form ultra-fine patterns on the surface of large diameter strips, single-wafer type devices are more advantageous and are gradually becoming mainstream. Naturally, single-wafer etching equipment
If the etching speed is the same, the throughput is lower than that of a batch type etching apparatus. Therefore, in single-wafer etching apparatuses, measures have been taken to increase the discharge efficiency, such as by using a magnetic field to generate magnetron discharge or by generating hollow cathode discharge.

FIG. 4 shows a schematic configuration of a conventional dry etching apparatus using magnetron discharge. In the figure, 81 is a vacuum container, 82 is a cathode, 83 is a substrate to be etched, 84 is a matching circuit, 85 is a high frequency power source, and 86 is a bar magnet 86a.
are arranged in the order of N5NS, 87 is a movement ms for moving the magnetic field generator 86 parallel to the cathode 82, 88 is a gas inlet, 89 is a gas exhaust port, and 90 is an insulator. In this device, electrons move cycloidally in a region where the electric field crossing the sheath formed on the surface of the cathode 82 and the magnetic field formed by the magnetic field generator 86 are perpendicular to each other, forming a dense plasma. The substrate to be etched 83 is etched at high speed by the ions in this plasma. Furthermore, since the magnetic field generator 86 is reciprocated, plasma can be uniformly formed, and the substrate to be etched 8
3 can be etched uniformly.

However, this type of device has the following problems. That is, as shown in FIG. 5(a), dense plasma 1j on the gap flows into the magnet 1! A spatial potential difference is created between 91 and the other regions, so that ions which should be perpendicularly incident on the substrate to be etched are bent. On the other hand, such ion bending does not occur in a direction perpendicular to the scanning direction (moving direction) of the magnetic field. Therefore, in a pattern parallel to the magnetic field scanning direction, the mask 9
2, the object to be etched 93 is etched perpendicularly to the pattern perpendicular to the magnetic field scanning direction.
), an undercut occurs in the etched shape. In other words, there is a problem in that the processed shapes of the orthogonal patterns are different.

On the other hand, in order to solve the above-mentioned problem, the present inventors proposed a dry etching device having a structure in which a magnetic field generator is placed on the back side of the anode opposite to the cathode (Japanese Patent Application No. 1126/1983).
No. 6). As a result, the drawback that the etching shapes differ in the orthogonal patterns as described above could be solved. However,
In this structure, r! on the cathode! Since the /i field is small, the self-bias inherent in reactive ion etching becomes large, leading to the problem that the ion bombardment effect becomes larger than when a magnetic field is placed directly under the cathode.

(Problems to be Solved by the Invention) As described above, the conventional apparatus has a problem in that when etching is performed using magnetron discharge, the processed shape of the orthogonal pattern is different. Furthermore, to prevent this,
Placing the magnetic field on the anode side led to the problem of increased irradiation damage due to ion bombardment.

The present invention has been made in consideration of the above circumstances, and its self-edging feature is that it can prevent the current situation where the orthogonal pattern is processed in a different shape, and it also aims to reduce irradiation damage caused by ion bombardment. An object of the present invention is to provide a dry etching device of 1q.

[Structure of the Invention] (Means for Solving the Problems) The gist of the present invention is that, in order to prevent ions from being bent by a magnetic field, a magnetic field generator is connected to the back surface of an electrode opposite to the electrode on which the substrate to be etched is placed. It is to be placed on the side. In addition to this, another magnetic field generator is placed around the outer periphery of the container in order to reduce the self-bias.

That is, the present invention provides a dry etching apparatus using magnetron discharge, including a container having a first electrode on which a substrate to be etched is placed and a second electrode disposed opposite to this electrode; means for supplying gas to the container; means for exhausting the gas in the container; means for applying high frequency power to the first electrode or the first and second electrodes; a first magnetic field applying means for applying a magnetic field between each of the N rods disposed on a side opposite to the side facing the first electrode, and moving the magnetic field in a direction perpendicular to the direction in which each electrode faces; A second magnetic field applying means is provided on the outer periphery of the container and applies a magnetic field between each of the electrodes in a direction perpendicular to the direction in which these electrodes face each other.

(Function) With the above configuration, the electrode Ti (cathode) on which the substrate to be etched is placed and to which high frequency power is applied is located away from the magnetic field generator, etc., but the distance between the electrodes can be shortened and the etching pressure can be kept relatively low. By setting a low region vi (for example, on the order of 104 torr), the sheath formed on the cathode surface stretches, and the sheath having the DC electric field overlaps within the region covered by the magnetic field. As a result, magnetron discharge occurs in the area where the magnetic field and the DC electric field of the sheath are perpendicular to each other, forming a dense plasma and achieving a high etching rate. Furthermore, compared to the conventional example which has a magnetic field generation mechanism directly under the cathode, there is no magnetic field on the side closer to the substrate than the magnetron discharge region, and the movement of ions is not affected by the magnetic field. Therefore, the phenomenon in which the processed shapes differ between two types of orthogonal patterns as in the conventional example is prevented.

On the other hand, the cathode (first
is the magnetic field on the electrode). First, a magnetic field is supplied to the cathode surface by the first magnetic field applying means. The self-bias reduction effect of the second magnetic field applying means that supplies a magnetic field from around the container is determined by the relative magnitude relationship with the magnetic field supplied by the first magnetic field applying means. If the magnetic field on the cathode surface can be increased by supplying a magnetic field from the side of the container, a denser plasma will be formed and the plasma impedance will be lowered, resulting in a lower self-bias.

(Example) Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

FIG. 1 is a schematic diagram showing a dry etching apparatus according to an embodiment of the present invention. In the figure, 10 is a vacuum container, and inside this container 10, first and second electrodes 11 and 12 are arranged facing each other. The first electrode (cathode) 11 has a substrate 13 to be etched placed on its upper surface, and a high frequency power source 15 is connected to this electrode 11 through a matching circuit 14.
high-frequency power is applied. And the first electrode 11
The second electrode facing the is grounded.

Here, the second electrode 12 has a hollow structure as shown in FIG. 2, and a thin plate (for example, a stainless steel plate) on the lower surface
31 is provided with a plurality of gas blowing holes 12a.

Then, a gas introduction pipe 16 is connected to the second electrode 12,
Gas (for example, CHF3) is uniformly blown out from the lower surface of the second electrode 12 onto the surface of the base 13. Note that the areas of the first and second electrodes 11 and 12 are equal to each other, and the distance R between the electrodes 11 and 12 is, for example, 15[,
M] is set.

On the top surface of the second l112 outside the container 10,
One first magnetic field generator in which permanent magnets 19a are arranged in the order of N5NS is arranged in close proximity. This magnetic field generator 19 is
The first and second electrodes 11.12 through the second electrode 12
A predetermined thickness 1 is formed on the gate, and the gate is reciprocated in the direction of arrow P in the figure along the second electrode 12 by a shifting opening groove 20. Further, a plurality of permanent magnets 21a are located outside the container 1o at a position facing the side wall of the container 10.
A second magnetic field generator 21 is arranged. As shown in FIG. 3, this magnetic field generator 21 is constructed by arranging a plurality of permanent magnets 21a on the same circumference at equal intervals in the order of N5NS, and the first and second electrodes 11.1' A magnetic field in a direction perpendicular to these opposing directions is supplied between the two. Note that the first magnetic field generator and the moving mechanism 20 constitute the first magnetic field applying means of the present invention, and the second magnetic field generator 21 constitutes the second magnetic field applying means of the present invention. Ru.

Furthermore, a plurality of gas exhaust ports are provided at the bottom of the container 10, and a mechanical booster pump 23 is connected to these gas exhaust ports via a main valve 22. pump 24
is connected.

The gas supplied into the container 10 is exhausted by these pumps 23 and 24. Note that 25 and 26 in FIG. 1 indicate insulators, respectively.

With such a configuration, a predetermined gas is supplied into the container 10 to maintain the inside of the container 10 at a predetermined pressure, and the electrodes 11, 12
By applying high frequency power between the etching points and reciprocating the magnetic field generator 19, it is possible to form a high-density and uniform plasma on the substrate 13 to be etched, thereby uniformly etching the substrate 13 at high speed. be able to.

Here, without using the second magnetic field generator 21,
First F! 1@Configuration in which the generator 19 is placed on the anode 12 side (configuration similar to the earlier application, Japanese Patent Application No. 11266/1983)
Now, when the distance between electrodes 11 and 12 is 40 [m],
Etching progresses with the best uniformity. And the distance between poles is 4
0 [8], the magnetic field at the cathode surface is about 140 Gauss, and the self-bias is about 200 [V] when CHF3 gas is 10' [torr, applied high frequency: l 1 [W/cm2]. there were.

On the other hand, in the case of the configuration of this embodiment in which the second magnetic field generator 21 is installed, the magnetic field at the cathode surface is about 180 Gauss, and the self-bias under the same conditions as above is about 120 Gauss.
V]. In other words, by adding the second magnetic field generator 21, the ion bombardment effect can be reduced, and ion radiation damage can be reduced.

On the other hand, when comparing the processed shape after etching, in the same configuration as the previous application, when the distance between the poles is less than 1i11t10, it is similar to the conventional case where the magnet is located directly under the electric standard on which the substrate to be etched is placed. The processed shapes of the orthogonal patterns were slightly different. However, the distance between poles is 10
[8] In the above cases, no difference in processed shape was observed at all.

Further, even in the configuration of this embodiment in which the second magnetic field generator 21 was further added, the above-mentioned difference in the processed shape was hardly observed when the distance between the poles was 10 [s+] or more.

Next, the self-bias reduction effect by the second wi field generator 21 will be explained.

First, a plurality of P-type Si wafers with a surface orientation (100) and a resistivity of 6 to 8 [Ωα] were prepared, and each of the apparatus shown in FIG. 1 and the apparatus from which the second VII field generator 21 was removed was prepared. into the container 10, and set the CHF3 gas pressure to 10°' [torr].
Etching was performed for 3 minutes under the condition of applied high frequency power of 1 EW/cm2]. Then, B If is set to an accelerating voltage of 1
After ion implantation at 30 [KeV] and a dose of '3013 Ccttr4, 950 ['C] wet oxidation was performed for 5 hours. Next, the wafer was immersed in an HF aqueous solution to peel off the oxide film on the surface, and etching was performed again for 1 minute. After that, when the wafer is observed under a microscope, the second magnetic field generator 2
When etching is performed using equipment that does not use 1, approximately 10'
[A stacking fault of 0m4J was observed. On the other hand, when etching was performed using the apparatus shown in FIG. 1, the above defects were hardly observed.

According to this embodiment, since high-density plasma is formed between the first and second electrodes 11 and 12 using magnetron discharge, it is possible to increase the etching speed. It has the following advantages: That is, since the first magnetic field generator 19 is disposed not on the first i-pole 11 on which the substrate 13 to be etched is placed, but on the back side of the second electrode 12, the substrate to be etched is removed from the density plasma region. It is possible to prevent inconveniences such as ions incident on the magnetic field 13 being bent by the magnetic field, and to eliminate the phenomenon that the processed shapes of the orthogonal patterns are different. Moreover, since the second magnetic field generator 21 is disposed around the outer periphery of the container 10, the self-bias can be lowered, thereby making it possible to reduce damage caused by ion irradiation. Moreover, the electrode 11.
12 areas are formed to be equal to each other, and the substrate 1 to be etched is
Since the gas is uniformly supplied to the surface of the wafer 3, etching can be made more uniform, and it is possible to sufficiently cope with future large-diameter wafers.

Note that the present invention is not limited to the embodiments described above. For example, as a moving mechanism for moving the first magnetic field generator, it is also possible to use a belt, chain, or the like provided in a closed loop so as to have an endless track. In this case, since the moving direction of the first magnetic field generator can be defined in one direction and the magnet can always be opposed to the second electrode, it is also possible to further increase the etching speed. Furthermore, as the first magnetic field applying means, an electromagnet may be used instead of the permanent magnet and the moving mechanism, and the magnetic field caused by the electromagnet may be moved along the second electrode.

That is, it is possible to use the stator of a linear motor as the first magnetic field applying means.

Further, as the second magnetic field generator, it is not necessarily necessary to arrange N5NS alternately, and furthermore, the number of magnets arranged around the magnet is not limited in any way. Furthermore, the same effect can be obtained by arranging electromagnets around the container instead of permanent magnets. Furthermore, an electromagnet, such as a linear motor, for forming a moving magnetic field may be provided around the container. others,
Various modifications can be made without departing from the spirit of the invention.

[Effects of the Invention] As described in detail above, according to the present invention, the first magnetic field applying means is arranged on the back side of the electrode opposite to the N pole on which the substrate to be etched is placed, so that the ions caused by the magnetic field are bending can be prevented, and differences in the processed shapes of orthogonal patterns can be eliminated. Furthermore, since the second magnetic field applying means is provided on the outer periphery of the container, the self-bias can be lowered, and irradiation damage caused by ion bombardment can be reduced. Therefore, it can be effectively used for microfabrication of various semiconductor devices.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a dry etching apparatus according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing an example of the arrangement of the first and second electrodes used in the above-mentioned apparatus, and FIG. Schematic diagram showing an example of the arrangement of the second magnetic field generator used in the device, No. 4
The figure is a schematic configuration diagram showing a conventional device, and FIG. 5 is a schematic diagram for explaining the problems of the conventional device. 10... Vacuum container, 11... First electrode, 12...
- Second electrode, 13...substrate to be etched, 14...
・Matching circuit, 15... High frequency 'R source, 16...
・Gas supply pipe, 19...first magnetic field generator, 2o...
- Moving mechanism, 21... second magnetic field generator, 22...
Main valve, 23... mechanical booster pump,
24...Oil rotary pump, 25.26...Insulator, 3
1...Metal plate. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3

Claims (6)

[Claims] (1) A container equipped with a first electrode on which a substrate to be etched is placed and a second electrode arranged opposite to this electrode, a means for supplying gas into the container, and a means for supplying gas in the container. a means for evacuating the first electrode or the first and second electrodes;
a means for applying high-frequency power to the electrodes; and a means for applying high frequency power to the electrodes of the electrodes; a first magnetic field applying means that moves in a direction perpendicular to the facing direction; and a second magnetic field applying means arranged on the outer periphery of the container and applying a magnetic field in a direction perpendicular to the facing direction between each of the electrodes. A dry etching device comprising: (2) The first magnetic field applying means includes a permanent magnet having a rod-shaped or closed-loop magnetic pole gap in which N poles and S poles are arranged with gaps alternately, and the magnet is connected to the second electrode. 2. The dry etching apparatus according to claim 1, further comprising a moving mechanism that moves along the dry etching apparatus. (3) The moving mechanism is comprised of a belt or chain having an endless track disposed on a side opposite to the first electrode of the second electrode. Dry etching apparatus according to scope 2. (4) The dry etching apparatus according to claim 1, wherein the means for supplying gas into the container sprays the gas uniformly onto the surface of the substrate to be etched. (5) The means for uniformly blowing gas onto the surface of the substrate to be etched includes forming the second electrode in a hollow shape and providing a large number of gas blowing holes on the surface of the electrode facing the first electrode. 5. The dry etching apparatus according to claim 4, wherein one or more gas supply holes are formed on opposite surfaces of the dry etching apparatus. (6) The second magnetic field applying means is comprised of permanent magnets or electromagnets arranged alternately in the order of north pole and south pole on the outer periphery of the container. Dry etching equipment described in Section 1.