JPS634081A - 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:This device is provided with a gas branching switch 36, etc., as means for selecting gases. The gas supplied from a gas source 11 through a mass flow controller 12 is selectively supplied to a plasma chamber 4 of an ion source 2 and to the neighborhood of the sample 22 on a disk 18 by using the switch 36. This device is also provided with a circulator 38, etc., as means for selecting microwaves. The microwave electric power outputted from a microwave oscillator 10 is selectively supplied to the plasma chamber 4 of the ion source 2 and to the neighborhood of the sample 22 on the disk 18 by using the circulator 38.

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,
It is equipped with a plasma chamber 4 for creating plasma, a magnetic field coil 6 for plasma confinement, an extraction electrode system 8 for extracting the ion beam 14 from the plasma chamber 4, etc.
The plasma chamber 4 is supplied with, for example, two
．． 45 GHz microwave power is supplied and the gas source 11
A gas (for example, a reactive gas) is supplied from the ion source 2 through a mass flow controller 12 for flow rate adjustment, and thereby an ion beam 14 containing, for example, reactive ions is extracted from the ion source 2 .

A movable shutter 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 30 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 the shutter 24, etc., 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, the energy of the ion beam 14 is high in the pre-etching stage (but the damaged parts of the sample 22 due to etching (for example, parts such as lattice defects) are This is unlikely to be a problem because it is removed by the step-by-step etching, but when the etching ends, some 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 ECR type ion source that irradiates the sample with an ion beam, a gas source that supplies gas, and a microwave power generator. a microwave oscillator; a gas switching means that switches and supplies gas from the gas source to the ion source and the vicinity of the sample; and a microwave that switches and supplies the microwave power from the microwave oscillator to the ion source and the vicinity of the sample. It is characterized by comprising a wave switching means and a magnetic field generating means for generating a magnetic field in the vicinity of the sample.

[Effect]

By switching the gas switching means and microwave switching means to the ion source side, it is possible to irradiate the sample with an ion beam from the ion source, thereby producing an ion beam with a large etching rate and excellent anisotropy for the sample. Etching is performed. By switching the side gas switching means and the microwave switching means to the sample side, it is possible to generate microwave discharge near the sample and generate plasma, and the magnetic field generating means confines the plasma with the magnetic field and generates plasma near the sample. It works to increase plasma density, thereby increasing etching efficiency. Therefore, ion etching is performed at a high etching rate while minimizing damage to the sample. Therefore, in this etching apparatus, for example, it is possible to switch between ion beam etching in the pre-etching stage and ion etching in the post-etching stage, thereby minimizing damage to the sample and preventing a drop in the etching rate. Can be done.

[Embodiment] 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, a gas branching switch 36 etc. is provided as a gas switching means, and as described above, the Unakasu source 11
The gas supplied from the ion source 2 via the mass flow controller 12 is switched and supplied to the plasma chamber 4 of the ion source 2 and the vicinity of the sample 22 on the disk 18 using the gas branch switch 36. 37a and 37b are piping for this purpose.

It also includes a circulator 38 etc. as a microwave switching means, and the microwave power output from the microwave oscillator 10 as described above is transferred to the circulator 38.
The ion source 2 is used to selectively supply the plasma to the plasma chamber 4 of the ion source 2 and the vicinity of the sample 22 on the disk 18. 39a and 39b are waveguides for this purpose.

In addition, the shutter 24 and the disk 18 serve as magnetic field generating means.
An annular magnetic field coil 52 having an inner diameter so as to surround at least the sample 22 on the disk 18 is provided between them.

Furthermore, this embodiment is provided with a control device 48 that controls switching of the gas branching switch 36, the circulator 38, and various other devices.

Therefore, the shutter 24 is opened and the gas branch switch 36 is opened.
By switching the circulator 38 to the ion source 2 side, the sample 2 on the disk 18 is transferred from the ion source 2 to the ion source 2 side.
Ion beam etching can be performed by irradiating 2 with an ion beam 14. On the contrary, by closing the shutter 24 and switching the gas branching switch 36 and the circulator 38 to the sample 22 side, plasma 50 is generated by macro wave discharge between the disk 18 and the shutter 24, and ion etching of the sample 22 is performed. Can be done.

Further, 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, the density of the plasma 50 will be increased (and therefore, 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 (in this way, the magnetic field suppresses the divergence of the ion beam 14 when the energy is lowered and the beam current irradiated onto the sample 22 It can also be expected that the density, that is, 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 using, for example, a rough vacuum evacuation device 32 and a high vacuum evacuation device 34, and the gas branching switch 36 and circulator 38 are ionized. The ion beam 14 of a desired size is drawn out from the ion source 2 with the shutter 24 closed, and the beam current is measured via an amplifier 28 etc. to obtain a desired beam current. Vacuum container 1 at this time
The degree of vacuum within the chamber 6 is approximately 10-' to 10-STorr. 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 etched together with the sample 22 by the ion beam 14 (or by the plasma 50) at substantially the same etching rate as the sample 22, 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 switches between ion beam etching using the ion beam 14 and ion etching using the plasma 50.

That is, the shutter 24 is closed and the gas branch switch 36 is closed.
Then, the circulator 38 is switched to switch the gas from the gas source 11 and the microwave power from the microwave oscillator IO to the sample 22 side. 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 vessel 16 can be adjusted to a level convenient for generating the plasma 50 by, for example, stopping the high-vacuum evacuation device 34 or operating only the rough evacuation device 32. degree (e.g. 10-' to 1O-2 Tor
(approximately r).

This causes the disk 18 and the shaft 7, which are rotating at high speed, to
A plasma 50 is generated between the disks 24, and the plurality of samples 22 and the detection object 42 mounted on the disk 18 pass through the region of the 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 eV), so the damage to the sample 22 is very small. Therefore, it is possible to efficiently etch the sample 22 to a predetermined final stage while minimizing damage to the sample 22, or, from a different perspective, by removing the damaged parts caused by the ion beam etching in the previous process. can. 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.

Although an example has been described above in which the control device 48 is used to automatically switch between ion beam etching and ion etching, the control device 48 may not be provided and both etchings may be switched manually, for example.

〔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. Furthermore, since the microwave oscillator and the like are shared, the configuration is relatively simplified.

[Brief explanation of 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...ECR type ion source, 10...Microwave oscillator, 11...Gas source, 14...Ion beam, 16
...Vacuum container, 18...Disk, 22...Sample, 24...Shutter, 36...Gas branch switch,
38...Circulator, 48...Control device, 50
...Plasma, 52...Magnetic field coil.

Claims (1)

[Claims] (1) In an apparatus for dry etching a sample housed in a vacuum container, EC irradiates the sample with an ion beam.
An R-shaped ion source, a gas source that supplies gas, a microwave oscillator that generates microwave power, a gas switching means that switches and supplies gas from the gas source to the ion source and the vicinity of the sample, An etching apparatus comprising: microwave switching means for switching and supplying microwave power from a wave oscillator to an ion source and a vicinity of a sample; and a magnetic field generation means for generating a magnetic field in the vicinity of a sample.