JPH0251228A - Plasma dry processor - Google Patents

Abstract

PURPOSE:To strictly control a magnetic field, and to eliminate the disorder of a magnetic field intensity distribution near a wafer and the loss of the function of a mask material by composing a plasma dry processor of a magnetic field generating coil, and a pulse voltage generator for applying a periodic pulse voltage thereto. CONSTITUTION:A wafer 17 as a material to be etched is placed at a predetermined position on a lower electrode 13, and etching gas is supplied into a reaction vessel 11 as designated by an arrow D. Simultaneously, the gas is discharged from a discharge port 11a, and so controlled that the vessel 11 becomes a predetermined gas pressure. If high frequency power is supplied to the electrode 13 in this state, a high frequency electric field is formed between the electrodes 12 and 13 in a direction of an arrow E, and a plasma 18 is generated. In this case, when a periodic pulse voltage is applied from a pulse voltage generator 16 to the solenoid coils 15a-15f of a magnetic field generating coil 15, a periodic magnetic field is generated in a direction of an arrow F perpendicular to the high frequency electric field. This magnetic field can be formed uniformly in parallel with the pair of electrodes 12, 13 by regulating the amplitudes of the voltages Va-Vf of pulse electrodes 16a-16f.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a plasma dry processing apparatus that utilizes the interaction between an electric field and a magnetic field, and particularly to its magnetic field generation mechanism.

(Prior art) Conventionally, as a technology in this field, Japanese Patent Application Laid-Open No. 59-1
．． There was one described in Publication No. 39627. below,
Its configuration will be explained using figures.

FIG. 2 is a sectional view showing an example of the configuration of a conventional plasma dry processing apparatus described in the above-mentioned document.

This plasma dry processing apparatus is a dry etching apparatus, and has a high frequency electric field generating mechanism and a magnetic field generating mechanism within the reaction vessel 1-. The reaction vessel 1- has an inlet (not shown) for introducing an etching gas and an exhaust port 2 for discharging the etching gas.

The high-frequency electric field generation mechanism includes a pair of electrodes including an upper electrode 3 and a lower electrode 4 arranged opposite to each other, and a high-frequency power source 5 for supplying high-frequency power to the electrodes. Also,
The magnetic field generator 1:h is the lower side of the 1U part electrode 3 and the lower electrode 4
It is composed of permanent magnets 6 provided on the two sides of -C. ” On the lower side of the permanent magnet 6 on the side of the two-part electrode 3,
A protective film 7 is provided. This protective film 7 is made of quartz, fluororesin, silicon, high purity aluminum, etc.
This is to protect the permanent magnet 6 from corrosion and rust caused by plasma. A susceptor 8 is provided on the second side of the permanent magnet 6'' on the lower electrode 4 side, and a wafer 9 to be subjected to dry etching' is placed at -E of the susceptor 8.

In the plasma dry processing apparatus constructed as described above, dry etching of the wafer 9 is performed as follows.

First, an etching gas is introduced into the reaction vessel 1 as indicated by arrow A and simultaneously exhausted from the exhaust port 2 to maintain the inside of the reaction vessel 1 at a constant gas pressure. This etching gas is used so that the film to be etched on the wafer 9 changes from, for example, 5102 to Si3N4.
Depending on the situation, a mixed gas of CF4 and 02 or C2FB,
C3FB, ClIF5, etc. are used.

In this state, a plasma 10 is formed by applying a high frequency power of, for example, several MH7 to several tens of MT-(1) between the upper electrode 3 and the lower electrode 4.

Then, a magnetic field is formed by the permanent magnet 6 in the direction of arrow C, which is perpendicular to the direction of the high-frequency electric field shown by arrow B. As a result, the electrons in the plasma 1-0 undergo cycloid motion due to the interaction between the electric and magnetic fields perpendicular to each other, and are effectively used to dissociate the etching gas.
Dissociation efficiency is increased. In this manner, dry etching is performed on the wafer 9.

2. Description of the Related Art As semiconductor devices have become highly integrated in recent years, the aspect ratio of a pattern (the ratio of a pattern's depth dimension to its surface dimension) has been increasing. Therefore, in order to respond to high-precision patterning techniques, dry etching techniques that can obtain high etching rates at low pressures have become indispensable.

(Problem to be solved by the invention) However, the plasma dry processing apparatus with the above configuration,
Etching precision, etching rate, etc. were not always satisfactory.

That is, the plasma dry processing apparatus described above simply has an N pole and an S pole.
A permanent magnet 6 with opposing poles is placed near the electrode 3.4, and it is not possible to strictly control the magnetic field strength or its uniformity, so the interaction between the electric and magnetic fields is effectively used. Yu was not enough.

Furthermore, during plasma discharge, the plasma density increases every month due to the interaction between the electric field and the magnetic field, which causes a problem in that the magnetic field strength distribution near the wafer 9 is disturbed due to the temperature rise of the permanent magnet 6.

Furthermore, due to the temperature rise of the wafer 9, the dry etching resistance of the photoresist etc. used as a mask material decreases, causing problems such as it no longer functioning as a mask material, and it is difficult to solve these problems. Ta.

The present invention solves the problems of the above-mentioned prior art, in that the magnetic field strength and its uniformity cannot be strictly controlled, that the magnetic field strength distribution near the wafer is disturbed, and that the function of the mask material may be lost. The present invention provides a plasma dry processing apparatus that solves the above problems.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a high-frequency electric field generating mechanism that has a pair of electrodes arranged oppositely in a reaction vessel and generates a high-frequency electric field between the electrodes, and In the plasma processing apparatus, the magnetic field generator is provided with a magnetic field generator that generates a magnetic field in a direction substantially orthogonal to the high-frequency electric field. The magnetic field generating coil is composed of a magnetic field generating coil and a pulse voltage generator that applies a periodic pulse voltage to the magnetic field generating coil.

(Function) According to the present invention, since the plasma dry processing apparatus is configured as described above, the magnetic field generating coil and the pulse voltage generator that applies a periodic pulse voltage to the magnetic field generating coil can strictly control the magnetic field. This makes it possible to effectively utilize the interaction between electric and magnetic fields.

Moreover, a high-density plasma state and a low-density plasma state are periodically formed by the periodic pulse voltage, thereby preventing a rise in the temperature of the wafer. Therefore, the dry etching resistance of the mask material does not become low F, and its function is maintained. Furthermore, disturbances in the magnetic field strength distribution due to temperature rise, such as those in permanent magnets, are accurately prevented.

Therefore, the above problem can be solved.

(Example) FIG. 1 is a sectional view of a plasma dry processing apparatus showing an example of the present invention. This plasma dry processing apparatus is used as a dry etching apparatus, and its configuration will be explained below.

Inside the reaction vessel 11, a pair of electrodes consisting of a flat plate-shaped two-part electrode 12 and a lower electrode 13 are arranged facing each other. The two-part electrode 12 is grounded, and the lower electrode 13 is connected to a high frequency power source 14. These pairs of electrodes 12.13
A high frequency electric field generation function is constituted by the high frequency electrode 14 and the like.

A plurality of magnetic field generating coils 15 are provided to surround the pair of electrodes 12,13. The magnetic field generation coil 15 includes, for example, six solenoid coils 15a.
~15f, each connected to the pulse power sources 16a~16f of the pulse voltage generator 16. A magnetic field generation mechanism is constituted by the magnetic field generation coil 15, pulse generator 16, and the like.

Dry etching using the plasma dry processing apparatus configured as described above is performed as follows.

First, a wafer 17 as a material to be etched is placed at a predetermined position on the lower electrode 13'2, and etching gas is supplied into the reaction vessel 11 as shown by the arrow. At the same time, the etching gas is discharged from the exhaust port 11-a to control the inside of the reaction vessel 11 to a predetermined gas pressure.

In this state, if high frequency power is supplied to the lower electrode 13, a high frequency electric field in the direction of arrow E is formed between the electrodes 12 and 13, and plasma 18 is generated.

At that time, each solenoid coil 1 of the magnetic field generation coil 15
When a periodic pulse voltage is applied from the pulse voltage generator 16 to 5a to 15f, a periodic magnetic field is generated in the direction of arrow F orthogonal to the high frequency electric field.

The pulse waveforms of the voltage and current supplied from the pulse voltage generator 16 to the magnetic field generating coil 15 are shown in FIGS. 3 and 4, for example. Figure 3 shows the pulse voltage generator 16.
FIG. 4 is a pulse current waveform diagram flowing through the magnetic field generating coil 15.

In FIG. 3, the low voltage Vmin at time τ1 and the time τ
The high voltage Vrnax of 2 applies a pulse voltage varying with a period τ from each pulse power source 16a to 1-6f to the corresponding solenoid coil 15a to 15f, respectively. As a result, a pulse current in which a low current Imin and a high current 1max change at a period τ flows through each solenoid coil 1.5a to 15f as shown in FIG. 4, and a periodic magnetic field is generated in the direction of the arrow F mentioned above. occurs. This magnetic field is generated by the pulsed power source 1.
By adjusting the magnitude of the voltages Va-V'' of 6a to 16f, the electrodes 12.13 can be formed parallel to the pair of electrodes 12.13 with good uniformity.

At time τ2 when the voltages 31 to Vf of the pulse power supplies 16a to 16f reach the high voltage Vmax, the electrodes 12.1
Electrons in the plasma 18 formed during the three-dimensional period move in a cycloid motion under the action of an electric field and a magnetic field that are orthogonal to each other. Thereby, the etching gas is effectively dissociated and the dissociation efficiency is increased. Therefore, a high density plasma is formed and the concentration of active species involved in etching is increased. On the other hand, at time τ1 when the voltages Va to Vf reach the low voltage Vmin, the effect of the magnetic field is small, resulting in a low-density plasma state.

In this way, since the high-density plasma state and the low-density plasma state are periodically formed on the surface of the wafer 17, the time τ1
．． By appropriately setting the ratio of τ2, the ratio of high voltage Vmax, low voltage Vmin, etc., it is possible to suppress the temperature rise of wafer 17 and control the ratio of ions to radicals on the surface of wafer 17.

In this embodiment, a magnetic field generating coil 15 and a pulse voltage generator 16, which can control the magnetic field, are used in place of the conventional permanent magnet, so that the magnetic field strength and its uniformity can be strictly controlled. can. Therefore, it becomes possible to effectively utilize the interaction between electric and magnetic fields. In addition, disturbances in the magnetic field strength distribution caused by temperature rise, such as in permanent magnets, can be accurately prevented. Furthermore, since the temperature rise of the wafer 17 is suppressed, the dry etching resistance of the mask material is maintained, and its function as a mask material is not impaired.

Note that the present invention is not limited to the illustrated embodiment, and can be modified in various ways, such as the following modifications.

(1) In FIG. 1, a glazma dry etching device is illustrated as an example of a plasma dry processing device, but the present invention is also applicable to other plasma dry processing devices such as a plasma deposition device, and similar effect can be obtained.

(2) In Figure 1, six solenoid coils 1.5a~
15f is provided, but the number may be other than six, and other types of coils may be used. Also,
The shapes of the solenoid coils 15a to 15f, the electric coils 1112, 13, etc. are not limited to those shown in the drawings, and can be freely modified according to the purpose.

(3) Although the six pulse power supplies 16a to 16f are provided in correspondence with the six solenoid coils 15a to 15f, these pulse power supplies 16a to 16f may be controlled individually or collectively. You may. Moreover, it is also possible to use 16f as a collective power source for each pulse power source 1.6a.

(Effects of the Invention) As described above in detail, according to the present invention, the magnetic field voltage generation mechanism is constructed with a plurality of magnetic field generation coils and a pulse voltage generator instead of conventional permanent magnets, so that each coil By applying a periodic pulse voltage to the magnetic field, the magnetic field can be precisely controlled. Therefore, it becomes possible to strictly control the magnetic field strength and the uniformity of its distribution, and it also becomes possible to accurately control the ratio of ions to radicals on the wafer surface.

Furthermore, since a high-density plasma state and a low-density plasma state are periodically formed on the wafer surface due to the periodic pulse voltage, the temperature rise of the wafer can be controlled by appropriately setting the pulse frequency, etc. . Therefore, the mask material etc. can reliably perform its function and be subjected to accurate plasma drying treatment.

Therefore, it is possible to obtain a highly accurate and highly reliable plasma dry processing apparatus that can arbitrarily control the magnetic field and temperature depending on the purpose.

[Brief explanation of the drawing]

FIG. 1 is a plasma dry processing apparatus showing an embodiment of the present invention;
2 is a sectional view showing an example of the configuration of a conventional plasma dry processing apparatus, FIG. 3 is a pulse power waveform diagram of the pulse voltage generator of FIG. 1, and FIG. FIG. 3 is a pulse current waveform diagram flowing through the magnetic field generating coil shown in the figure. 11... Reaction container, 12... Upper electrode, 13... Lower electrode, 1.5... Coil for magnetic field generation, 16... Pulse voltage generator, 17
...Wafer, 18...Plasma.

Claims (1)

[Scope of Claims] A high-frequency electric field generating mechanism that has a pair of electrodes arranged opposite to each other in a reaction vessel and generates a high-frequency electric field between the electrodes, and generates a magnetic field between the electrodes in a direction substantially orthogonal to the high-frequency electric field. A plasma dry processing apparatus comprising a magnetic field generating mechanism, the magnetic field generating mechanism comprising: a plurality of magnetic field generating coils provided to surround the pair of electrodes; and a periodic pulse voltage applied to the magnetic field generating coils. A plasma dry processing apparatus characterized in that it is configured with a pulse voltage generator for applying.