JPS634080A - Etching device - Google Patents

Abstract

PURPOSE:To suppress the damage of a sample and to prevent the decrease in an etching rate with a device for dry etching of the sample in a vacuum vessel by selectively executing ion beam etching and ion etching. CONSTITUTION:A plasma forming means is constituted of a disk 18 serving also as an electrode for high-frequency discharge, a shutter 24, a gas source 11, a mass flow controller 12, a high-frequency power source 38, etc. A selection means is constituted of a gas branching switch 36, a control unit 48, etc., and a magnetic field generating means is constituted by providing an annular magnetic field coil 52 having the bore to enclose the sample 22 on the disk 18 between the shutter 24 and the disk 18. The gas branching switch 36 supplies the gas to be supplied from the gas source 11 through the mass flow controller 12 by selecting the same to a plasma chamber 4 of an ion source 2 and to the neighborhood of the sample 22 on the disk 18.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an etching device for dry etching a sample housed in a vacuum container, and particularly to an etching device that can switch between ion beam etching and ion etching. Regarding.

[Conventional technology]

FIG. 4 is a schematic diagram showing an example of a conventional etching apparatus. This device is an ion beam etching device,
A disk 18 is provided in the vacuum container 16 and is rotated at high speed by a drive device 20.
A plurality of samples 22 are mounted on the periphery of the sample 8 .

Then, the ion beam 14 from the ion source 2 is applied to this sample 22.
It is etched by irradiating it.

Specifically, the ion source 2 is an ECR type ion source in this example, and includes a plasma chamber 4 for creating plasma, a magnetic field coil 6 for plasma confinement, and an extraction electrode for extracting the ion beam 14 from the plasma chamber 4. The plasma chamber 4 is supplied with microwave power from a microwave oscillator 10, and gas (for example, reactive gas) is supplied from a gas source 11 via a mass flow controller 12 for adjusting the flow rate. , thereby the ion source 2
For example, an ion beam 14 containing reactive ions is extracted from the ion beam.

A movable inner lid 24 is provided on the path of the ion beam 14 from the ion source 2 to interrupt the ion beam 14. 26 is its driving device. Further, 28 and 3o are amplifiers for measuring the beam current of the ion beam 14 irradiated onto the shutter 24 or the disk 18. Note that the disk 18 and the shaft 24 are each insulated from the ground.

The sample 22 is, for example, as shown in FIG. 5, in which the surface of a substrate 221 made of silicon is covered with an etching layer 222 made of silicon oxide, which is further covered with a resist 223 having a desired pattern. .

When etching the sample 22, for example, after adjusting the beam current of the ion beam 14 to a predetermined value using a shutter 24 or the like, the shutter 24 is opened and the ion beam is applied to the sample 22 on the disk 18 rotating at high speed. 14. As a result, the etching layer 222 of each sample 22 is etched according to the pattern of the resist 223, as shown, for example, by the broken line in FIG.

[Problem that the invention seeks to solve]

When etching the sample 22 using the ion beam 14 as described above, even if the energy of the ion beam 14 is high in the pre-etching stage, the damaged parts of the sample 22 (for example, parts such as lattice defects) due to etching are This is unlikely to be a problem because it is scraped away by step-by-step etching, but when the etching ends, a certain amount of this damaged portion remains within the sample 22, which causes various problems when manufacturing devices etc. using the sample 22.

To deal with this, it may be possible to reduce the energy of the ion beam 14 as much as possible near the end of etching to minimize damage to the sample 22, but if you do so,
Due to the characteristics of the ion source 2, the beam current of the ion beam 14 inevitably decreases significantly, resulting in a decrease in the etching rate and a new problem in terms of productivity.

SUMMARY OF THE INVENTION An object of the present invention is to provide an etching apparatus that can minimize damage to a sample and prevent a decrease in etching rate.

[Means for solving problems]

The etching apparatus of the present invention is an apparatus for dry etching a sample housed in a vacuum container, and includes: an ion source that irradiates the sample with an ion beam; a plasma generation means that generates plasma near the sample by high-frequency discharge;
It is characterized by comprising a magnetic field generating means for generating a magnetic field in the vicinity of the sample, and a switching means for switching between the operation of the ion source and the operation of the plasma generating means.

[Effect]

When the ion source is operated, the sample is irradiated with an ion beam, thereby performing ion beam etching on the sample at a high etching rate and with excellent anisotropy. - When the plasma generation means is operated, plasma is generated near the sample by high-frequency discharge, and the magnetic field generation means uses the magnetic field to confine the plasma and increase the plasma density near the sample, thereby increasing etching efficiency. . Therefore, ion etching is performed at a high etching rate while minimizing damage to the sample.

The switching means can operate the ion source to perform ion beam etching in the pre-etching stage, and operate the plasma generation means to perform ion etching in the post-etching stage, thereby minimizing damage to the sample. At the same time, a decrease in etching rate can be prevented.

〔Example〕

FIG. 1 is a schematic diagram showing an etching apparatus according to an embodiment of the present invention. Components that are the same as or correspond to those in FIG. 4 are given the same reference numerals and their explanations will be omitted.

In this embodiment, plasma generating means is composed of a disk 18 which also serves as an electrode for high frequency discharge, a shutter 24, a gas source 11, a mass flow controller 12, a high frequency power supply 38, and the like.

Further, the gas branching switch 36, the control device 48, etc. constitute a switching means. Furthermore, between the shutter 24 and the disk 18, at least the sample 22 on the disk 18 is
A magnetic field generating means is constituted by providing an annular magnetic field coil 52 having an inner diameter that surrounds the magnetic field coil 52.

The gas branch switch 36 transfers the gas supplied from the gas source 11 via the mass flow controller 12 to the ion source 2.
The plasma is switched between the plasma chamber 4 and the vicinity of the sample 22 on the disk 18. The control device 48 controls the ion source 2, the gas branch switch 36, the high frequency power source 38, etc., in response to a signal from a counting device 46, which will be described later, for example. The switch 40a switches the electrical connection of the disk 18 between the amplifier 30 and the high-frequency power source 38, and the switch 40b, for example, works in conjunction with the switch 40a to switch the electrical connection of the shutter 24 between the amplifier 28 and the ground. This is to switch to .

A gas for plasma generation (for example, a reactive gas) is supplied between the disk 18 and the shutter 24 via the gas branch switch 36 as described above. The high frequency power supply 38 supplies high frequency (including microwaves, for example 13.
A voltage of 56 MHz) is applied. As a result, sample 22
Plasma 50 of the gas can be generated by generating a high frequency discharge between the disk 18 attached thereto and the shutter 24.

The magnetic field coil 52 is excited by a DC power source (not shown) and mainly generates a magnetic field for plasma confinement in the vicinity of the sample 22. The reason for providing this is as follows. That is, even if the plasma 50 is simply generated between the shatter 24 and the disk 18, if there is no means to confine it, it will be difficult to increase its density ((Thus, it will be difficult to improve the etching rate of the sample 22 by the plasma 50. On the other hand, if the magnetic field coil 52 is provided to generate a magnetic field for plasma confinement, the plasma density near the sample 22 can be increased and the etching efficiency of the plasma 50, that is, the etching rate can be further increased.

Note that the magnetic field coil 52 may be operated during irradiation with the ion beam 14, and in this case, the magnetic field suppresses the divergence of the ion beam 14 when the energy is lowered, and the beam current density irradiated onto the sample 22 is reduced. In other words, it can be expected that the etching rate by the ion beam 14 will be increased.

Next, an example of the overall operation of the above device will be explained.

For example, if a predetermined stage of etching is performed from the beginning, for example, sample 22.
Ion beam 1 until near the end stage where damage to the
Sample 22 is etched using etching method No. 4. That is, first, the inside of the vacuum container 16 is evacuated to a predetermined degree of vacuum by using, for example, a rough vacuum evacuation device 32 and a high vacuum evacuation device 34.

Then, switch the gas branch switch 36 to the ion source 2 side,
With the shutter 24 closed, the ion beam 14 of a desired size is extracted from the ion source 2, and the beam current is measured via an amplifier 28 etc. to obtain the desired beam current. The degree of vacuum inside the vacuum container 16 at this time is 10-' to 10-'T or
It is about r. At that time, switch 40b (and 40a
) is set to measurement side A. Thereafter, the shutter 24 is opened, and the ion beam 14 is irradiated onto the samples 22 on the disk 18 rotating at high speed, thereby etching each sample 22.

In that case, the problem of damage to the sample 22 can be solved by later ion etching using the plasma 50, so etching can be performed by increasing the energy of the ion beam 14, and therefore, the etching rate can be increased and the etching can be performed using ion beam etching. Because of this, etching with excellent anisotropy can be performed.

Next, when the etching reaches a predetermined stage, for example near the end stage mentioned above, the ion beam 14 is stopped and the plasma 50 is generated instead to etch the sample 22.

In that case, the detection that the etching has reached a predetermined stage may be performed by known means such as etching time management, but here, the
In place of the sample 22, an etching amount detecting device consisting of a detecting body 42, a detecting device 44, and a counting device 46 is used.

For example, as shown in FIG. 2, the detection body 42 has a layer 422 made of the same material as the etching layer 222 of the sample 22 to be etched, and a thin film layer 423 made of a material different from the layer 422, which are alternately laminated. on the substrate 421. Although the spacing T between the laminations of the thin film layers 423 may be arbitrary, it is preferable to set the spacing T to be equal because calculations described later become easier. The detection device 44 is, for example, an emission spectrometer or a mass spectrometer, and detects that the thin film layer 423 in the detection object 42 has been etched by emission spectroscopy or mass spectrometry, and each time detects the etching, for example, in a pulsed manner. A detection signal S is output.

An example of this is shown in FIG. The counting device 46 includes, for example, a counter, and counts the number of detection signals S from the detection device 44.

The detection object 42 on the disk 18 is exposed to the sample 2 by the ion beam 14 (or by the plasma 50 described later).
2 and at approximately the same etching rate as that, and the detection signal S as described above is obtained. In this case, since the interval T between the thin film layers 423 is predetermined, the number of detection signals S corresponds to the etching amount (etching thickness) of the detection object 42 and, in turn, to the etching amount of the sample 22. Therefore, the amount of etching on the sample 22 at any stage can be accurately detected by (number of detection signals S) x (interval T).

Therefore, for example, by using the above-mentioned etching amount detection device, it is possible to detect when the etching of the sample 22 has progressed to near the end stage (for example, one or two steps before the final etching amount in terms of the interval T). Signal control device 48
give to In response, the controller 48 controls the ion source 2.
Switching is performed such as stopping the operation of the plasma generating means and starting the operation of the plasma generating means such as the high frequency power source 38 instead.

That is, the shutter 24 is closed and the operation of the ion source 2 is stopped. Further, the gas branching switch 36 is switched to supply the above-mentioned gas into the vacuum container 16, and the switches 40a and 40a
0b is switched to the plasma generation side B, and a high frequency voltage as described above is applied between the disk 18 and the shutter 24 from the high frequency power supply 38. Further, the magnetic field coil 52 is excited to generate a magnetic field for plasma confinement. In that case, the degree of vacuum in the vacuum container 16 can be determined by, for example, stopping the evacuation device 34 for high vacuum, or stopping the evacuation device 32 for rough evacuation.
The degree of vacuum (for example, about 10° to 1° Torr) is made convenient for generating plasma at 5° by operating the

As a result, plasma 50 is generated between the disk 18 rotating at high speed and the shatter 24, and the plurality of samples 22 and the detection object 42 mounted on the disk 18 pass through the area of the plasma 50, and at that time, plasma 50
etched by ions inside. In that case, the plasma density near the sample 22 is increased by the magnetic field coil 52, so the etching rate is high (and the energy of the ions is small (for example, about several tens of electrons), so the damage to the sample 22 is extremely large. Therefore, the sample 22 can be efficiently etched to a predetermined final stage while minimizing damage to the sample 22, or from another perspective, removing the damaged portion caused by the ion beam etching in the previous step. The fact that the etching has reached the final stage is detected by the etching amount detection device described above, and the generation of the plasma 50 is thereby stopped and the etching is completed.

Therefore, according to the etching apparatus as described above, the sample 22
Damage to the etching layer can be suppressed as much as possible, and a decrease in the etching rate can be prevented.

In the above, an example has been described in which the control device 48 is used to automatically switch between the operation of the ion source 2 and the operation of the plasma generation means such as the high frequency power source 38. The two operations may be switched by, etc.

Alternatively, the gas source 11 and the mass flow controller 12 may be provided separately for the ion source 2 and for the plasma generation means, without providing the gas branching switch 36.

〔Effect of the invention〕

As described above, according to the present invention, ion beam etching and ion etching can be performed by switching.
Thereby, damage to the sample can be suppressed as much as possible and a decrease in the etching rate can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing an etching apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged partial cross-sectional view of an example of the detection body used in the apparatus shown in FIG. FIG. 3 is a schematic diagram showing an example of a detection signal output from the detection device of FIG. 1. FIG. 4 is a schematic diagram showing an example of a conventional etching apparatus. FIG. 5 is a partial sectional view showing an example of a sample. 2... Ion source, 11... Gas source, 14... Ion beam, 16... Vacuum container, 18... Disk,
22... Sample, 24... Shutter, 36... Gas branch switch, 38... High frequency power supply, 48... Control device, 50... Plasma, 52... Magnetic field coil.

Claims (1)

[Claims] (1) An apparatus for dry etching a sample housed in a vacuum container, which includes an ion source that irradiates the sample with an ion beam, a plasma generation means that generates plasma near the sample by high-frequency discharge, and a magnetic field near the sample. What is claimed is: 1. An etching apparatus comprising: magnetic field generating means for generating a magnetic field; and switching means for switching between operation of an ion source and operation of a plasma generating means.