JPS62169418A - Dry etching unit - Google Patents

Abstract

PURPOSE:To utilize magnetron discharge for etching a substrate quickly, by arranging a magnetic applying means such as a magnetic field generator on the back side of an electrode facing to another electrode on which the substrate is carried. CONSTITUTION:A magnetic field generator 19 with permanent magnet arranged in the order of NSNS is mounted near the top face of a second electrode 12 outside a container 10. The magnetic field generator 19 for forming a predetermined magnetic field between first and second electrodes 11 and 12 through the second electrode 12 is moved reciprocally in the directions along the second electrode 12 as indicated by arrows P by means of a moving mechanism 20. A predetermined gas is supplied into the container 10 so as to keep a pressure within the container 10 at a predetermined level. Meanwhile, a high-frequency voltage is applied between the electrode 11 and 12 and the magnetic field generator 19 is moved reciprocally. In this manner, uniform plasma with a high density can be produced over a substrate to be etched 13 and, therefore, the substrate 13 can be etched uniformly and quickly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a dry etching apparatus, and more particularly to a dry etching apparatus using magnetron discharge.

[Technical background of the invention and its problems]

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 In this method, high frequency power is applied between the 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 diameter of Si wafers will continue to increase to 8 inches and 12 inches. Therefore, in order to uniformly form ultra-fine patterns on the surface of a large-diameter wafer, a single-wafer type apparatus is more advantageous, and is 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. 12 shows a schematic configuration of a conventional dry etching etching apparatus using magnetron discharge.

In the mouth 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 R source, 8
6 is a magnetic field generator in which bar magnets 86a are arranged in the order of N5NS, 87 is a moving mechanism that moves the LA field generator 86 in parallel with the cathode 82, 88 is a gas inlet, 89 is a gas exhaust port, 90
indicate the respective insulators. In this device, the cathode 8
Electrons move cycloidally in a region where the electric field across the sheath formed on the surface of the magnetic field generator 86 and the magnetic field formed by the magnetic field generator 86 are perpendicular to each other, and a dense plasma is formed. The substrate to be etched 83 is etched at high speed by the ions in this plasma. Further, since the magnetic field generator 86 is moved back and forth, plasma can be uniformly formed, and the substrate 83 to be etched can be uniformly etched.

However, this type of device has the following problems. That is, as shown in FIG. 2(a), a spatial potential difference is generated between the dense plasma region 1491 on the magnet gap and the non-dense plasma region, and as a result, ions that 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 object to be etched 93 is etched vertically along the mask 92 as shown in FIG. 2(b), but in a pattern perpendicular to the magnetic field scanning direction, as shown in FIG. As shown in (C), an undercut occurs in the etched shape.In other words, there is a problem in that the processed shapes of orthogonal patterns are different.

[Purpose of the invention]

The present invention has been made in consideration of the above circumstances, and its purpose is to enable high-speed etching of a substrate to be etched using magnetron discharge, and to prevent the phenomenon in which the processed shapes of orthogonal patterns are different. The object of the present invention is to provide a dry etching device that can be used for dry etching.

[Summary of the invention]

The gist of the present invention is to arrange a magnetic field applying means such as a magnetic field generator on the back side of the electrode facing the electrode on which the substrate to be etched is placed, in order to prevent ions from being bent by the magnetic field.

That is, the present invention provides a dry etching apparatus using magnetron discharge, which includes a first electrode on which a substrate to be etched is placed, a second electrode disposed opposite to this electrode, and a container including a λl. means for supplying gas into 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, and the second electrode. magnetic field applying means disposed on a side opposite to the first electrode to apply a magnetic field between each of the electrodes and to move the magnetic field along the second electrode. It is.

〔Effect of the invention〕

In the present invention, the electrode (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 is short and the etching pressure is set in a relatively low region (for example, 10 By setting the sheath on the cathode surface (on the order of 2 torr), the sheath formed on the cathode surface stretches, and the sheath with the DC electric field overlaps within the area covered by the magnetic field.As a result, the area where the magnetic field and the DC electric field of the sheath are orthogonal A magnetron discharge occurs in the wafer, 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. In addition, the self-bias generated in the sheath is larger than when the magnetic field generating means is provided directly under the cathode, so the energy of the ions is large and it is difficult to be affected by the potential difference between the magnetron discharge region and the normal discharge region. Become.

Therefore, the phenomenon in which the processed shapes differ between orthogonal 2fl patterns as in the conventional example is prevented.

[Embodiments of the invention]

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 from 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 is uniformly blown out from the lower surface of the second electrode 12 onto the surface of the base 13. In addition, the first and second
The areas of the electrodes 11.12 are mutually equal, and the areas of the electrodes 11.1
The distance 1111tR between the two is set to, for example, 15[#].

Further, an annular vibrator 17 having a plurality of gas blowing holes on the inner circumferential side is arranged between the first and second electrodes 11 and 12. A gas introduction pipe 18 is connected to this vibrator 17 . And from this vibrator 17, container 1
Gas is introduced into the etching chamber 1, and together with the gas supply from the second electrode 12, the gas is uniformly supplied to the surface of the substrate 13 to be etched.

On the upper surface of the second electrode 12 outside the container 10,
One 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 forms a predetermined magnetic field between the first and second electrodes 11 and 12 through the second electric fi 112, and the moving mechanism 20 moves the second electrode 12 along the direction indicated by the arrow in the figure. It is to be moved back and forth in the P direction. Note that the magnetic field generator 19 and the moving mechanism 20 constitute the magnetic field applying means of the present invention.

Further, a plurality of gas exhaust ports are provided at the bottom of the container 10, and a mechanical booster pump 22 is connected to these gas exhaust ports via a main valve 21. pump 23
is connected.

The gas supplied into the container 11 is exhausted by these pumps 22 and 23. Note that 24 and 25 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.

Figure 3 shows that a C12/CHI-3 (20%) mixed gas is supplied into the container 10 at a total amount of 20 [sccm], the pressure inside the container is 4 [Pa], and the applied high-frequency power is 2 [W/cI].
Distance between electrodes of cathode drop voltage when R2 is set (electrode 11.
12 is a diagram showing changes depending on the distance between Solid line B in the diagram
As shown in the figure, when there is no magnetic field, it is constant regardless of the distance between the poles, but when there is a magnetic field (for example, 900 Gauss), as shown by the solid line A in the figure, the cathode drop voltage decreases as the pole-to-pole distance becomes shorter. Also, the gills of single crystal Si.

Comparing the cutting speed with a distance between poles of 1126 [mm], it is about 400 [people/min] without a magnetic field, whereas it reaches 700 [people/min] with a magnetic field.

On the other hand, when comparing the shape of the etching attack, it was found that when the interspecies distance was less than 10 ram3, the shape of the orthogonal patterns was slightly different, similar to the conventional case where a magnet exists directly under the electrode on which the substrate to be etched is placed. It was something. However, when the distance between the poles was 11M10 [a+] or more as in this example, no difference in the processed shape was observed at all.

From the above results, it can be seen that this example forms a dense plasma by the action of a magnetic field and achieves a high etching rate. It is clear that the conventional problem that the processed shapes of orthogonal patterns are different can be solved without impairing the advantages of the conventional apparatus.

By the way, in order to obtain a high etching rate simply by the action of a magnetic field, the first and second electrodes 11 and 12 do not need to have equal areas. However, in the case of the present invention, since it is a short distance plasma device operated at a low pressure of 10 [Pal or less], the discharge path is not formed at a short distance, but is formed to swell from the periphery of the substrate to be etched. Ru.

FIG. 4 is a diagram schematically showing discharge when the area of the second electrode 12 is larger than that of the first electrode 11. Discharge path 3
2 tends to concentrate around both electrodes 11 and 12. Therefore, in the configuration shown in FIG. 4, for example, when gas is supplied from the opposing second electrode 12 and a 5-inch diameter wafer is etched, the etching rate will decrease toward the center of the wafer, as shown by the solid line B in FIG. The peripheral parts are faster in comparison.

On the other hand, in this embodiment in which the areas of the first and second electrodes 11 and 12 are equal, the discharge path swells somewhat around the electrodes and is formed in a cylindrical shape, but the etching rate distribution is
As shown by the solid line A in the figure, it is approximately uniform.

In addition, the first and second 1! In the method of making the poles 11 and 12 equal in area, it is not necessarily necessary to make the areas of the electrodes themselves equal.5For example, as shown in FIG.
The same effect can be obtained if the electrodes 2 are covered with an insulator 33 and the areas of the parts that effectively move as electrodes during discharge are made equal.

Furthermore, the gas flow also influences the etching rate distribution. As already mentioned, the areas of the first and second electrodes are made equal, and the gas blowing holes 12a of the second electrode 12 are formed in 11 pieces as shown in FIG. The distribution of the etching rate when gas is supplied is shown by the solid line A in FIG.

On the other hand, as shown in Fig. 7(b), the second electricity (Tetsu 12
If all but one of the gas blow-off holes 12a provided in the center are crushed, the etching rate distribution will be as shown by the solid line A in FIG. 8.

That is, although the etching rate increases slightly in the peripheral area, it is approximately equal overall. In addition, when only the ring-shaped pipe 17 is used without blowing out gas from the second IL&12, the etching distribution with a large difference between the central part and the peripheral part is shown as shown by the solid line B in Fig. 8. becomes.

From the above, by making the first and second electrodes 11 and 12 have the same area and uniformly spraying the gas onto the substrate to be etched 13, it is possible to uniformly etch even a large diameter substrate to be etched. Become.

Further, the method of uniformly spraying gas onto the surface of the substrate to be etched has another effect of improving the etching rate ratio to SiO2 (Si/5iO2) depending on the structure. Now, as shown in FIG. 9, as the second electrode 1i12, a metal plate (for example, a stainless steel plate) 31 on which the gas blowing hole 12a is provided has a thickness T of 2 [M] and a diameter of 1 [mm].
When using a hole in which the holes are arranged at intervals of 10 cm,
As shown in FIG. 10, the etching rate ratio is only 2 to 3 at most. In the figure, the 0 mark shows the etching speed of 3i, the X mark shows the etching speed ratio, and the Φ mark shows the etching speed of S i 02.

On the other hand, when the thickness T of the metal plate 31 is 0.5 [s+] and when the diameter and distribution of the gas blowing holes 12a are exactly the same, the etching rate of Si is as shown in FIG. As the etching rate of SiO2 increases slightly, the etching rate of SiO2 decreases to below 1/''2j, and the selectivity improves markedly.

Although the reason for this cannot be clearly stated, it is believed that when the metal plate 31 is thin, the discharge enters the space of the second electrode 12, forming a kind of hollow cathode discharge and promoting gas dissociation. Conceivable. Therefore, the ratio between the thickness of the metal plate 31 and the diameter of the gas blowing hole 12a is important, and the ratio is 2
The following is desirable.

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 substrate 13 to be etched is placed on the back side of the second electrode 12 rather than the first electrode 11 on which the substrate 13 is mounted, ions incident on the substrate 13 to be etched from the high-density plasma region are bent by the magnetic field. It is possible to prevent inconveniences such as the occurrence of a difference in the processed shape of orthogonal patterns. In addition, since the areas of the electrodes ff111 and 12 are made equal to each other and the gas is uniformly supplied to the surface of the substrate 13 to be etched, it is possible to achieve more uniform etching, which is suitable for future large-diameter wafers. be able to cope with it adequately. Roughly speaking, gas is blown out at the bottom surface of the second electrode 12 (
) By forming the metal plate 31 forming the hole 12a to be sufficiently thin, the etching speed ratio (selectivity) between 3i as the object to be etched and SiO2 etc. as the mask can be increased.
There are advantages such as improved performance.

Note that the present invention is not limited to the embodiments described above. For example, the number of permanent magnets forming the magnetic field generator can be changed as appropriate depending on specifications. Furthermore, it is also possible to use a belt, chain, etc. provided in a closed loop so as to have an endless track as the movement 1 for moving the magnetic field generator.

In this case, the moving direction of the magnetic field generator is defined in one direction, and the second electrode is provided with a hole in which the magnet is always opposed, so that it is also possible to further increase the etching speed.

Furthermore, r11Sli! Instead of the permanent magnet and the moving mechanism, an electromagnet may be used as the applying means to move the magnetic field generated by the electromagnet along the second electrode.

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

Further, the distance between the electrodes is not limited to 15 [s+], and can be changed as appropriate according to specifications. however,
When the distance between the electrodes becomes 10 [mm] or less, ions are bent by the magnetic field, and differences in the processed shapes of the orthogonal patterns begin to occur. Further, if the distance between the electrodes exceeds 60 [mm], the magnetic field will not overlap with the sheath having the DC electric field, and the effect of magnetron discharge will decrease. Therefore, the distance between the electrodes is preferably 10 to 60 [mm]. Alternatively, the first and second electrodes can be arranged upside down and the substrate to be etched can be etched with its etching surface facing downward. In this case, an electrostatic chuck or the like may be provided on the lower surface of the first electrode. In addition, various modifications can be made without departing from the gist of the present invention.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing a dry etching device 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 device, and diagram M3 is a diagram showing the arrangement of the first and second electrodes used in the above device. 7) Characteristic diagram showing the relationship between the inter-electrode distance and the cathode drop voltage, Figure 4 is a schematic diagram showing the state where the area of the second electrode is larger than the first electrode, Figure 5 is a diagram showing the relationship between the electrode distance and the cathode drop voltage. A characteristic diagram showing the relationship between the position on the wafer and the etching speed due to the difference in area, Figure 6 is a schematic configuration diagram showing an example in which the electrode areas are equivalently equal, and Figure 7 is a schematic diagram showing an example of the arrangement of gas blowing holes. Figure 8 is a characteristic diagram showing the relationship between the position on the wafer and the etching rate in uniform gas supply and non-uniform gas supply, Figure 9 is a sectional view specifically showing the second electrode structure, and Figure 10 is A characteristic diagram showing the etching rate ratio of Sf and 5iQ2 when the metal plate thickness is 2 cm3. Figure 11 is a characteristic diagram showing the etching rate ratio of Sf and 5iQ2 when the metal plate thickness is 0.5 cm.
A characteristic diagram showing the etching speed ratio of Si, 5i02 in the case of [s+], FIG. 12 is a schematic configuration diagram showing a conventional device, and FIG. 13 is a configuration diagram for explaining problems with the conventional device. 10... Vacuum container, 11... First electrode, 12...
- Second electrode, 13...substrate to be etched, 14...
・Matching circuit, 15...High frequency power supply, 16.18
...Gas supply pipe, 17...Vibe, 19...Magnetic field generator, 20...Movement mechanism, 21...Main valve, 22...Mechanical booster pump, 23...Oil rotary pump , 24.25.33... Insulator, 31...
- Metal plate, 32...discharge path. Applicant's representative Patent attorney Takehiko Suzue, cough government haiku poet (V) - Figure 5 Figure 6 (a) (b) Figure 7 Width Iha 1m? Fig. 10 Fig. 11 (a) (b) (c) Fig. 13

Claims (9)

[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;
means for applying high frequency power to the electrodes;
A dry etching apparatus comprising a magnetic field applying means that moves along the electrode. (2) The magnetic field applying means includes a permanent magnet having a bar-shaped or closed-loop magnetic pole gap in which N poles and S poles are arranged with gaps alternately, and a permanent magnet that moves the magnet along the second electrode. The dry etching apparatus according to claim 1, characterized in that the dry etching apparatus comprises a moving mechanism that moves. (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 magnetic field applying means comprises a stator of a linear motor. (5) The dry etching apparatus according to claim 1, wherein the distance between each electrode is set to 10 to 60 [mm]. (6) The first and second electrodes have the same area.
Dry etching equipment described in Section 1. (7) 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. (8) 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. 8. The dry etching apparatus according to claim 7, wherein one or more gas supply holes are formed on opposite sides of the dry etching apparatus. (9) The dry etching apparatus according to claim 1, wherein the first electrode is provided with an electrostatic chuck mechanism.