JPS60103620A - Plasma treatment device - Google Patents

Abstract

PURPOSE:To perform the plasma treatment for sample such as etching and thin film formation at a high speed by providing an electrode with plural magnets and putting plural samples on the magnets facing said magnets. CONSTITUTION:A lower electrode 10 and an upper electrode 11 shaped of flat plates are arranged in parallel. The lower electrode 10 carries a sample table 12 on which plural pieces of wafers 13 as samples are put and it is rotatable and is connected to a high-frequency source 15 through an aligning circuit 14 for equalizing impedances of the low and upper electrodes 10 and 11. Meanwhile, in the upper electrode 11, plural magnets 16 are arranged to generated a magnetic field in the direction which crosses the direction of a high-frequency electric field formed between the low and upper electrodes 10 and 11 at right angles. To this upper electrode 11, a D.C. bias application circuit 17 is connected. Furthermore, a gas introducing pipe 18 for supplying a reactive gas for a reactor 9 and a gas exhaust vent 19 are provided to generate plasma P.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to plasma processing technology, and particularly to technology that is effective when used in etching and thin film formation using plasma.

[Background technology]

As a conventional batch type plasma etching apparatus, the first
There is something like the one shown in the figure. (Electronic materials November 1981
Monthly special issue, Kogyo Kenkyukai, November 10, 1981, pages 131-136). In the figure, l is a reaction vessel, which can be opened and closed and has a structure with good airtightness.

2 and 3 are a flat plate-shaped lower electrode and an upper electrode, respectively.
The partner electrodes are arranged in parallel. A sample stage 4 on which a plurality of wafers 5 can be loaded is loaded on the lower electrode 2 . The lower electrode 2 is connected to a high frequency power source 6, and the other end of the high frequency power source 6 is grounded. -The hero part electrode is also grounded. 7 is a gas introduction pipe for supplying a reaction gas into the reaction vessel 1; 8 is a pump 4;
! K (not shown) is a gas exhaust port for exhausting the reaction gas in the reaction vessel 1. Further, the symbol P in the figure indicates plasma.

For example, when etching the silicon oxide film on the wafer 5 using the above-mentioned apparatus, a reaction gas such as CHF is used and is introduced from the gas introduction pipe 7. By discharging the gas from the gas exhaust port 8, the inside of the reaction vessel 1 is maintained at a pressure that facilitates plasma generation. Therefore, a high frequency power of about 10 or more MH2 is applied between the electrodes 2 and 3 by the high frequency power supply 6, and the reactive gas is discharged between the upper electrode 3 and the lower part 11&20, plasma P is generated, and the silicon on the wafer 5 is The part of the oxide film to be etched, that is, the organic photosensitive resin film (photoresist film) as an etching mask
The silicon oxide film in the areas that have not been etched is etched.

By the way, the present inventor uses the above-mentioned apparatus to form fine patterns of semiconductor integrated circuits, and demands faster etching of silicon oxide films, etc., and as patterns become finer, etching accuracy is improved. I thought it was necessary to increase it. Therefore, by increasing the radio frequency power density and decreasing the reaction gas pressure, the ions are accelerated to increase the etching rate, and the mean free path of the ions is increased, and the DC electric field is used to change the incident angle of the ions to the wafer loading surface. The idea was to perform precise etching in a direction perpendicular to the surface.

However, the incident energy of the ions increases,
It has been found that physical etching, ie sputtering, with a strong ion bombardment effect also occurs. Therefore, when ions collide with an insulating film such as a silicon oxide film or a PSG film, pinholes are created, and as a result, the pattern changes when wiring is performed, causing harmful effects. In addition, due to the above-mentioned factors, ions may
It has been found that the substrate formed under the silicon nitride film or the like collides with the substrate, thereby deteriorating the electrical characteristics of the semiconductor element formed on the substrate. Furthermore, it has been found that the particles collide with the photoresist film that serves as an etching mask, causing deformation and damage to the photoresist film.

In addition, the inventors have discovered that when the reaction gas pressure is lowered to perform etching with high precision, there are problems such as the reaction gas molecule concentration being low due to the low pressure state and etching efficiency becoming poor. revealed.

On the other hand, even when the plasma processing equipment described above is used for thin film formation technology, it is possible to increase the thin film formation speed based on the above-mentioned concept, but in this case, non-uniformity of the electric field occurs and it is not possible to form a thin film with a uniform thickness. The inventors have discovered that there are problems such as difficulty in forming.

The inventors of the present invention focused on the fact that the cause of the various problems described above lies in the movement of electrons during plasma processing, and as a result of extensive studies, they arrived at the present invention.

[Purpose of the invention]

An object of the present invention is to provide a technique that can increase the speed of plasma processing such as etching and thin film formation by plasma processing.

Another object of the present invention is to provide a technique that allows plasma processing to be performed without causing various damages to a sample.

Another object of the present invention is to provide a technique capable of forming highly concentrated plasma even under low pressure.

Another object of the present invention is to perform etching by plasma treatment;
The purpose of the present invention is to provide a technique that can speed up the processing speed without causing various damage to the sample during thin film formation, etc.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Summary of the invention]

A brief overview of typical inventions disclosed in this application is as follows.

That is, a plurality of magnets that generate a closed loop magnetic field in a direction perpendicular to the high-frequency electric field are provided on the electrode, and
By loading a plurality of samples on the electrode facing the electrode, plasma processing such as etching and thin film formation can be performed on the samples at high speed.

[Embodiment 1] FIG. 2 is a schematic diagram showing a batch type plasma etching apparatus which is an embodiment of the present invention.

In the figure, 9 is a reaction container, which has a structure that can be opened and closed and has good airtightness. Reference numerals 10 and 11 denote a lower electrode and an upper electrode each having a flat plate shape, and the partner electrodes are arranged in parallel. The lower electrode 9 has a rotatable structure on which a sample stage 12 is loaded and a plurality of wafers 13 as samples are loaded thereon. The lower electrode 10 is connected to a high frequency power source 15 via a matching circuit 14 for equalizing the impedances of the upper electrode 11 and the lower electrode IO.

On the other hand, a plurality of magnets 16 are provided inside the upper electrode 11, and the magnets 16 generate a magnetic field in a direction perpendicular to the direction of the high-frequency electric field formed between the lower electrode 10 and the upper electrode 11. It is set up to occur. A DC bias application circuit 17 is connected to this upper electrode 11 . 18 is a gas introduction pipe for supplying a reaction gas into the reaction container 9. 19 is a gas exhaust port for exhausting gas by a pump or the like (not shown). Also,
The symbol P in the figure indicates plasma.

FIG. 3 shows a plurality of magnets 1 provided within the upper electrode 11.
6 is a partially exploded plan view showing the arrangement of wafers 6 and 6, in the case where eight wafers are processed at once. Figure 4 shows
4 is a sectional view taken along the line IV-IV' in FIG. 3. FIG. In the figure, 8
Although shown to process one wafer at a time,
It is not limited to this. The virtual phase line 13 shown in the figure is a hypothetical state in which eight wafers are loaded at equal intervals on a sample stage (not shown).

Reference numeral 20 denotes a disk-shaped bottom plate, which is a part of forming the upper electrode. The magnets 16 are located above the circular center of each wafer 13 when the lower electrode (not shown) is stationary, and are fixed at regular intervals along one circle of the bottom plate 20. There is. Additionally, the magnet 16 is arranged such that its longitudinal direction faces toward the center of the bottom plate 20.

Reference numeral 21 denotes a ring that is a part of the upper electrode 11, and its height dimension is slightly larger than the height dimension of the magnet 16. The disk-shaped top plate 22 is connected to the bottom plate 20. In combination with the ring 21, the upper electrode 11 is formed.

FIG. 5 is a plan view of the magnet 16. 6 is a sectional view taken along the line Vl-VI in FIG. 5. FIG. FIG. 7 is a sectional view taken along the line ■-■ in FIG. 5. In the figure, 23 is a rectangular metal plate that serves as the bottom plate of the magnet 16.
Its longitudinal dimension is slightly larger than the diameter of the wafer that is the sample.

24 is a rectangular magnet whose longitudinal dimension is:
The diameter is slightly larger than the wafer diameter, which is the sample.
A magnet 25 whose longitudinal dimension is slightly smaller than this magnet 24
They are placed on the metal plate 23 in such a way that they are parallel to each other. Magnets 26 are parallel to each other and are erected on the metal plate 23 so as to be orthogonal to the longitudinal direction of the magnets 24 and 25. Further, the polarities of the magnets 24 and 25 are formed as shown in FIG. 7, and the magnetic field B shown by the arrow in the figure is formed in a direction perpendicular to the high frequency electric field.

Next, the operation of the nine devices described above will be explained.

A case will be described in which the silicon oxide film formed on the wafer 13 is selectively etched using a reactive gas such as CHF5. Reaction vessel 9 via gas exhaust port 19
The inside should be roughly drawn. Next, a reaction gas is introduced from the gas introduction pipe 18 and maintained at a low gas pressure of about 10-3 Torr. Therefore, the high frequency power supply 15
high frequency power is applied to both electrodes. Then, plasma indicated by P is generated. At this time, the upper electrode 11
Electrons are confined within the plasma loop by a magnetic field created by the plurality of magnets 16 provided in the wafer 13 in a direction perpendicular to the electric field and larger than the diameter of the wafer 13 with respect to the longitudinal direction of the magnets 16.

Furthermore, the electrons undergo cycloidal motion.

As a result, the dissociation and ionization of reactive gas molecules is enhanced. Thereby, high concentration plasma can be obtained even under low pressure. Then, the silicon oxide film on the wafer 13 is etched while the lower electrode 10 rotates. At this time, since the electrons are confined within the plasma loop, the layer of space charge created by positive ions gathering around the electrons formed on the wafer 7113, that is, the ion sheath (ion 5heath), becomes thinner and the lower part Electrode 1
The DC bias on the 0 side can be lowered. While the incident energy is thereby weakened, the ions directed by the DC electric field do not cause a deterioration of the electrical properties of the semiconductor device formed in the underlying substrate of silicon oxide. Moreover, it does not cause deformation or damage to the photoresist group, which is an etching mask. Therefore, it can be etched accurately and quickly.

In addition, in FIGS. 3 and 4, the magnet 16''lI: is provided inside the upper electrode, but it can also be attached to the upper surface of the upper plate 22 or the lower surface of the bottom plate 20, and the magnet can be easily attached. .The magnet 16 may be a permanent magnet or an electromagnet.

The former has the advantage of being compact, and the latter has the advantage of being able to arbitrarily set the strength of the magnetic force depending on the applied power.

[Embodiment 2] FIG. 8 is a perspective view showing a magnet provided on an electrode as another embodiment of the present invention. A pair of magnets 27 and 28 formed in a semicircular shape are opposed with the same polarity, and a highly permeable material 29, 30 such as iron material is interposed between the respective poles, and then these are welded together by means of welding force. They are connected together to form a substantially annular shape as a whole.

The internal space of the substantially annular magnet having the highly permeable materials 29 and 30 is preferably larger than the sample in order to uniformly plasma-treat the entire sample, which is a cedar treated body. and,
When such a magnet is installed on the upper electrode, it is attached to the lower surface of the upper electrode so that the direction B of the magnetic field is directed toward the center of the electrode, and when the electrode is stationary, it is located above each sample.

This magnet has an effect similar to that of the magnet shown in Example 1, and can be etched without causing deterioration of the electrical characteristics of the semiconductor element formed on the substrate under the silicon oxide film by ions. Etching can be performed accurately and quickly without causing deformation or damage to the photoresist film used as a mask.

In Examples 1 and 2, when fluoride is used as the reaction gas, the magnet is made of high-purity aluminum.

By coating with quartz, or Teflon, etc., it is possible to prevent sample contamination due to the reaction between the reaction gas and the magnet. Furthermore, the lifetime of the magnet can be extended by flowing a cooling medium between the magnet and the coating material and by preventing the temperature of the magnet from rising with a temperature control device provided outside the reaction system.

Also, the magnet may be an electromagnet or a permanent magnet, but
If the latter is used, it will be easier to handle and more compact.

Furthermore, although the lower electrode on which the sample is loaded is rotated, the upper electrode may also be rotated.

The present invention achieves the following by changing the reaction gas and reaction conditions.
Silicon, silicon oxide film, silicon nitride film,
It goes without saying that it can also be used to form various thin film layers such as molybdenum.

〔effect〕

1. By providing a plurality of magnets on the electrode, an effect can be obtained in which electrons are confined within a plasma loop by a magnetic field formed in a direction perpendicular to the electric field.

2. Since a plurality of magnets are provided on the electrodes, the effect that electrons perform cycloidal motion due to the magnetic field formed in the direction orthogonal to the electric field can be obtained.

3. By providing a plurality of magnets on the electrode, electrons are confined within the plasma loop by a magnetic field formed in a direction perpendicular to the electric field. Therefore, the ion sheath formed on the sample becomes thinner, and the DC bias on the electrode side on which the sample is loaded can be lowered.

4. By installing multiple magnets in electrical contact, the electrons are confined within the plasma loop by the magnetic field formed in the direction perpendicular to the electric field and perform cycloidal motion, which improves the dissociation of the reactant gas molecules.

The effect of increasing ionizability can be obtained.

5. By installing multiple magnets on the electrodes, the magnetic field formed in the direction perpendicular to the electric field confines electrons within the plasma loop, thins the ion sheath formed on the sample, and loads the sample. DC bias on the electrode side can be lowered. Therefore, the incident energy of the ions is reduced, and it is possible to perform etching without causing various kinds of damage to the sample.

6. By installing multiple magnets on the electrode, electrons are confined within the plasma loop by the magnetic field formed in the direction perpendicular to the electrode, and the ion sheath formed on the sample becomes thinner, causing the sample to The DC bias on the electrode side to be loaded can be lowered. Therefore, the adhesion energy of solid species for forming a thin film is reduced, and it is possible to form a thin film without causing various damage to the sample.

7. By providing a plurality of magnets on the electrodes, electrons are confined within the plasma loop by the magnetic field formed in the direction orthogonal to the electrodes, causing cycloidal motion. Therefore, the dissociation and ionization properties of the reaction gas molecules are enhanced, and a highly concentrated plasma can be obtained even under low gas pressure.

8. By providing multiple magnets on the electrode, electrons are confined within the plasma loop due to the magnetic field formed in the direction perpendicular to the electric field, and the ion sheath formed on the sample becomes thin υ. The DC bias on the electrode side on which the sample is loaded can be lowered. Therefore, the incident energy of the ions is reduced, and the effect is that the high frequency power density can be increased and the etching speed can be increased without causing various damage to the sample.

9. By installing multiple magnets on the electrodes, the magnetic field formed in the direction perpendicular to the electric field confines electrons within the plasma loop, thins the ion sheath formed on the sample, and loads the sample. DC bias on the electrode side can be lowered. (-(7)), the adhesion energy of solid species for thin film formation is reduced, and the effect is that the high frequency power density can be increased and the thin film formation speed can be increased without causing various damage to the sample. It will be done.

10. By providing a plurality of magnets on the electrodes, electrons are confined within the plasma loop by the magnetic field formed in the direction orthogonal to the electric field, and perform cycloidal motion.

Therefore, the dissociation and ionization properties of the reactive gas molecules are enhanced, so that even under low gas pressure, plasma processing speeds such as etching and thin film formation can be accelerated by high-concentration plasma.

11. The angle of incidence of ions is determined by the action of the DC electric field.

The direction of deposition of the solid species for thin film formation is oriented perpendicular to the sample loading surface. What's more, the electrode that loads the sample, or the electrode that faces the electrode that loads the sample, rotates while etching.

Plasma processing such as thin film formation can be performed.

Therefore, it is possible to obtain the effect that plasma processing can be performed with precise processing accuracy.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the above Examples and can be modified in various ways without departing from the gist thereof. Nor.

[Application field]

The above explanation has mainly been about the case where the invention made by the present inventor is applied to the manufacturing technology of semiconductor devices, which is the background field of application, but the invention is not limited to this. It can be applied to electronic components or object surface treatment technology.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram for explaining a conventional batch-type plasma etching apparatus, FIG. 2 is a schematic diagram for explaining a batch-type plasma etching apparatus according to an embodiment of the present invention, and FIG. , a partially exploded plan view showing an upper electrode in a batch type plasma etching apparatus according to an embodiment of the present invention, FIG. 4 is a sectional view taken along the line IV'-N in FIG. 3, and FIG. 6 is a sectional view taken along the line Vl--Vl in FIG. 5; FIG. 7 is a sectional view taken along the line ■-■ in FIG. 5; The figure is a perspective view showing a magnet as another example. 1.9... Reaction container, 2. lO...lower electrode, 3゜11...upper electrode, 4,12...sample stage, 5,13
...Wafer, 6,15...High frequency power supply, 7,18
...Gas inlet pipe, 8, 19...Gas exhaust port, 14.
・Matching circuit, 16.24, 25, 26, 27.28・
...Magnet, 17...DC bias application circuit, 2o...
・Bottom plate, 21...Ring, 22...Top plate, 23...
・Metal plate, 29,3o...high magnetic permeability material, P...plasma, B...magnetic field. Figure 1

Claims (1)

[Claims] 1. Plasma in which a plurality of samples are loaded on the first electrode of a first electrode and a second electrode provided opposite each other in a reaction vessel and subjected to plasma treatment. In the processing device, the second
A plasma processing apparatus characterized in that a plurality of magnets are provided on the electrode. 2. The plasma processing apparatus according to claim 1, wherein a rotational drive mechanism capable of rotating at least one of the first electrode and the second electrode is connected to the electrode. .