JP2001254188A - Inductively coupled plasma treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inductively coupled plasma treatment apparatus in which the supply of the high frequency power into a treatment chamber is not impeded by depositing a metal film on the surface of a dielectric window. SOLUTION: A plurality of slits 503 are formed in a mask member 50 mounted on the lower side of the dielectric window (a unified body of a window member 25 and a disposable plate 27). A part of the metal atoms ground from a sample during the plasma etching and scattered therearound is adhered to the surface of the mask member 50 to deposit the metal film, while no metal film is deposited on positions of the slits 503, and a blank area is formed. Since the passage of the induced current along a winding of a coil electrode 26 is broken by the blank area, no loss is generated in the high frequency power by the current.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an inductively coupled plasma processing apparatus.

[0002]

2. Description of the Related Art Sputter etching has been conventionally known as a method for performing fine processing on the surface of a workpiece.
In this method, a processing target having a processing pattern mask formed on a surface to be processed is housed in an airtight processing chamber. Then, while maintaining the processing chamber at a low pressure, a processing gas (Ar, Cl _2, or the like) is supplied into the processing chamber, and a high-frequency magnetic field is generated in the processing chamber to convert the processing gas into plasma. The ions contained in the plasma are accelerated by a bias voltage and collide with the surface to be processed of the object to be processed, thereby removing the unmasked portion of the surface to be processed (sputtering).

[0003] An inductively coupled plasma (ICP) processing apparatus is known as one of the apparatuses for performing the above processing. The ICP processing apparatus includes a window serving as a power inlet for supplying high-frequency power into the processing chamber, a coil electrode provided outside the window, and a high-frequency power supply for applying a high-frequency voltage to the coil electrode. . The window is generally composed of a dielectric such as quartz. Such a window is hereinafter referred to as a dielectric window.

[0004] The dielectric window is called a window in view of the functional aspect that a high-frequency magnetic field generated from the coil electrode serves as a window through which the high-frequency magnetic field enters the processing chamber. The shape of the dielectric window is not necessarily a window shape. There is no. On the other hand, when the shape of the dielectric window is determined, the shape of the coil electrode is substantially determined accordingly. For example, if the dielectric window has a disk shape,
A spiral coil is arranged on the back of the dielectric window (the side opposite to the processing chamber). When the dielectric window is cylindrical or bell-shaped, a spiral coil is mounted on the outer peripheral wall surface.

[0005]

In micromachining using an ICP processing apparatus, generally, metals (for example, Pt, Ir, N
In many cases, a conductive thin film made of i) or a metal oxide (for example, iridium oxide, tin oxide, or the like) is used as a processing target. When such a metal-based object is processed for a large number of times or for a long time, the metal sputtered by the plasma ions and scattered from the object gradually adheres to the surface of the dielectric window to form a film there. When the metal film is formed on the surface of the dielectric window in this manner, it becomes difficult to supply high frequency power from the coil electrode into the processing chamber. The present invention has been made to solve such a problem, and an object of the present invention is to provide an inductive coupling in which supply of high frequency power is not hindered by formation of a metal film on the surface of a dielectric window. An object of the present invention is to provide a plasma processing apparatus.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a processing chamber for accommodating an etching target containing metal atoms, and a method for introducing high-frequency power into the processing chamber. In an inductively-coupled plasma processing apparatus including a dielectric window provided in a processing chamber, a coil electrode disposed behind the dielectric window, and a high-frequency power supply for applying a high-frequency voltage to the coil electrode, during an etching process, The geometric shape of the metal film formed on the surface of the dielectric window facing the inside of the processing chamber of the dielectric window due to the metal atoms scattered from the object to be processed is a high frequency magnetic field generated by the coil electrode. A mask member for concealing a part of the surface of the dielectric window so that a current flow induced in the metal film is interrupted on the way by the action of Providing an inductively coupled plasma processing apparatus.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, when a metal film is formed on the surface of a dielectric window, the supply of high-frequency power into a processing chamber is inhibited because of the action of a high-frequency magnetic field generated in the metal film. It is considered that high frequency power is consumed by the induced current. In the case of the inductively coupled plasma processing apparatus, the induced current tends to flow in a direction substantially along the winding of the coil electrode. Therefore, in the ICP processing apparatus according to the present invention, by masking a part of the surface of the dielectric window facing the inside of the processing chamber (hereinafter, referred to as the inner surface of the dielectric window) with the mask member, The geometrical shape is such that the current flow induced by the high-frequency magnetic field generated by the coil electrode is interrupted on the way.

[0008] The mask member is configured in consideration of the shape of the dielectric window (and the coil electrode). For example, when the dielectric window has a disk shape, the mask member is formed of a plurality of disks extending substantially radially from the center of a disk made of the same material as the dielectric window and having substantially the same size as the dielectric window. May be formed.

When the mask member having the slit is mounted on the inner surface of the dielectric window, most of the metal atoms scattered from the object to be etched face the interior of the processing chamber of the mask member (hereinafter, the exposed surface of the mask member is referred to as the exposed surface). And only some of the metal atoms pass through the slit and adhere to the inner surface of the dielectric window. As a result, the metal film is formed only on the plurality of linear regions corresponding to the slits of the mask member on the inner surface of the dielectric window, but these regions are separated from each other in the winding direction of the coil electrode. Therefore, the above induced current does not flow. On the other hand, a metal film having a radial blank area corresponding to the slit is formed on the exposed surface of the mask member. Even if an induced electromotive force that generates a current along the winding of the coil electrode acts on this metal film, the induced current is generated because the path along the winding is divided into a plurality of sections by the blank region. do not do.

When the mask member is brought into close contact with the dielectric window, for example, when a metal film is formed on the inner peripheral wall surface of the slit, the metal film on the exposed surface of the mask member and the metal film on the inner surface of the dielectric window are thereby formed. There is a risk that the short circuit will occur with the film, and the above-described current interrupting action will be impaired. In order to prevent such a situation, it is preferable to dispose the mask member at a minute interval from the dielectric window. In this case, the insulation between the mask member and the dielectric window becomes more reliable. If the gap is too small, the gap between the mask member and the dielectric window may be closed by the edge of the metal film formed on the inner surface of the dielectric window, while the gap is too large. Then, there is a possibility that the metal atoms that have passed through the slit go around the back surface of the mask member and widely adhere to the inner surface of the dielectric window.
Such a problem can be solved, for example, by setting the distance between the mask member and the dielectric window to 0.1 to 0.5 mm.

The form of the mask member is not limited to the one having the slit as described above. For example, even if a star-shaped mask member having a plurality of extensions extending radially outward from the center is used, the above-described current interruption effect can be obtained.

When the dielectric window is cylindrical or bell-shaped, a substantially cylindrical mask member for concealing the inner wall surface is formed, and the mask member includes a plurality of mask members substantially parallel to the cylindrical generatrix. The generation of the induced current along the winding of the coil electrode can be prevented by providing the slit.

[0013]

According to the present invention, the problem that the supply of high frequency power is obstructed by the formation of the metal film on the surface of the dielectric window is solved. Therefore, the plasma etching process can be performed efficiently and stably for a long time or many times without cleaning or replacing the dielectric window.

[0014]

FIG. 1 is a schematic structural view of an ICP processing apparatus according to an embodiment of the present invention. ICP processing apparatus 1 of the present embodiment
Has an airtight processing chamber 20 for containing a sample 10 made of metal or metal oxide. A processing gas passage 21 is connected to an upper portion of the processing chamber 20, and a gas for plasma etching processing is supplied from the processing gas supply unit 22 into the processing chamber 20 through the processing gas passage 21. The pressure inside the processing chamber 20 is controlled to a low pressure by a pressure control mechanism including a rotary pump 31, a turbo molecular pump 32, a valve 33, a pressure controller 34, and the like.

At the bottom of the processing chamber 20, a lower electrode 23 for mounting the sample 10 is provided. The lower electrode 23 is connected to a first high frequency (R) through a first matching circuit 35.
F) connected to generator 36; First RF generator 3
6 applies to the lower electrode 23 a bias voltage for accelerating plasma ions generated in the processing chamber 20 toward the sample 10.

A circular dielectric receiving portion 202 having an opening is provided on an upper wall surface (ceiling) 201 of the processing chamber 20, and a disk-shaped window member 25 made of a dielectric material is disposed here. The inner surface of the window material 25 is concealed by a discard plate 27 (see FIG. 2), and a mask member 50 is mounted on the lower surface of the discard plate. On the other hand, a spiral coil electrode 26 is arranged on the upper surface of the window material 25. Coil electrode 2
6 is a second RF generator 38 via a second matching circuit 37.
It is connected to the. The second RF generator 38 applies a high frequency voltage for generating a high frequency magnetic field from the coil electrode 26 to the coil electrode 26.

FIG. 2 shows the structure of the mask member 50. FIG.
2A shows the mask member 50 viewed from below in the processing chamber 20, and FIG. 2B shows a cross section of the mask member 50 taken along the line IIB-IIB in FIG. As mentioned earlier, window material 2
5 is concealed by a discard plate 27. The whole of the discarded plate 27 and the window material 25 corresponds to a dielectric window according to the present invention. The mask member 50 is disposed in a circular opening 203 formed in the dielectric receiving portion 202 of the processing chamber 20, and is disposed below the disposal plate 27 by a ring-shaped mask support component 52 fixed to the ceiling 201 by screws 51. Supported. The upper surface of the mask member 50 has a step 5 along the circumference.
01 is formed, whereby a gap 502 is formed between the discard plate 27 and the mask member 50. Also,
A number of slits 503 are formed radially inside the step portion 501 of the mask member 50.

The process of forming a metal film on the surface of the dielectric window (the surface of the disposal plate 27 in this embodiment) as the plasma etching process proceeds will be described with reference to FIGS. 3A and 3B show a process of forming a metal film in a conventional ICP processing apparatus. FIG.
(A) and (B) show a process of forming a metal film in the ICP processing apparatus 1 of the present embodiment, and (C) is an enlarged view of a portion surrounded by a circle C in (B).

First, the process of forming a metal film in a conventional device will be described. High frequency power (RF) from the coil electrode 26 into the processing chamber 20 through the window material 25 and the waste plate 27
Is supplied, the processing gas in the processing chamber 20 is turned into plasma. The ions contained in the plasma are supplied to the lower electrode 2
3 is accelerated by the electric field generated by the bias voltage applied to the sample 3 and collides with the upper surface of the sample 10. By this ion collision, metal atoms are scraped off from the upper surface of the sample 10,
Spattering into the processing chamber 20 (sputtering; FIG. 3)
(A)). Part of the sputtered metal atoms is discarded 27
Reaches the surface and gradually deposits there. When the metal atom film 55 is formed on the surface of the discard plate 27 in this manner, an induced current is generated in the film 55 as described above and the high-frequency power RF is consumed. It becomes difficult to supply the high-frequency power RF, and finally the power supply stops (FIG. 3B). In this case, conventionally, the discard plate 27 has been washed or replaced with a new one.

Next, a process of forming a metal film in the device 1 of the present embodiment will be described. First, the process in which metal atoms are scattered in the processing chamber 20 during sputtering is the same as in the case of the conventional apparatus (FIG. 3A) (FIG. 4A).
Some of the sputtered metal atoms are gradually deposited on the lower surface of the mask member 50 to form a metal film 551, but no metal atoms are deposited on the slit 503. As a result, the metal film 551 has a circular shape in which a plurality of slit-shaped holes are radially opened. On the other hand, the other part of the sputtered metal atoms passes through the slit 503 of the mask member 50 and reaches the discard plate 27, where a plurality of elongated metal atoms having substantially the same shape and dimensions as the slit 503 are provided. A film 552 is formed (FIGS. 4B and 4C). As described above, in the apparatus according to the present embodiment, since the metal films 551 and 552 are separately formed on the surfaces of the mask member 50 and the discard plate 27, an induced current is generated along the winding direction of the coil electrode 26. Therefore, it is not difficult to supply the high-frequency power RF into the processing chamber 20 (FIGS. 4B and 4C).

In order to confirm the effect of the present invention, a conventional IC
Comparative experiments of etching rates using a P processing apparatus and an ICP processing apparatus configured according to the present invention were performed. In this experiment, platinum etching processing was performed a plurality of times using a quartz wafer (platinum thickness = 200 nm) with platinum (Pt) having a diameter of about 125 mm as a sample, and a change in the etching rate according to the number of processing times was examined. The etching rate is
The calculation was based on endpoint data obtained using a plasma monitor manufactured by Hamamatsu Photonics. The experimental results are shown in FIG. As can be seen from FIG. 5, in the conventional apparatus, the processing proceeded at a high etching rate only for the first time,
After the first time, the etching rate rapidly decreased as the number of treatments increased, and after the fifth time, the etching did not progress at all. This indicates that, as described above, the supply of the high-frequency power into the processing chamber sharply decreases, and the plasma generation efficiency sharply decreases. On the other hand, in the apparatus according to the present invention, even after the processing was performed 20 times or more, the same high etching rate as that of the first etching was maintained.

FIG. 6 is a view showing another form of the mask member. The mask member 60 in FIG. 6 has eight extending portions 603 that extend radially outward from the center. A step 601 is formed on the back surface of the distal end of each extension 603, whereby a gap 602 is formed between the mask member 60 and the discard plate 27. Even when such a mask member 60 is used, the same effect as that obtained by the mask member 50 can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an ICP processing apparatus according to an embodiment of the present invention.

FIG. 2A is a view of the mask member viewed from below, and FIG.
2A is a cross-sectional view taken along line IIB-IIB in FIG.

FIGS. 3A and 3B are diagrams showing a process of forming a metal film on the surface of a dielectric window in a conventional ICP processing apparatus.

4A and 4B are diagrams showing a process of forming a metal film on the surface of a dielectric window in a conventional ICP processing apparatus.
(C) is an enlarged view of a portion surrounded by a circle C in (B).

FIG. 5 is a graph showing the results of a comparison experiment of etching rates performed using a conventional ICP processing apparatus and an ICP processing apparatus configured according to the present invention.

FIG. 6 is a diagram showing another form of a mask member,
(A) is a view of the mask member viewed from below, and (B) is a view of (A).
Sectional drawing in line VIB-VIB.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Inductive coupling type plasma processing apparatus (ICP processing apparatus) 10 ... Sample 20 ... Processing chamber 23 ... Lower electrode 25 ... Window material 26 ... Coil electrode 36, 38 ... High frequency (RF) generator 50, 60 ... Mask member 501, 601: step portion 502, 602: gap 503: slit

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Osamu Tsuji F-term in the Samco International Laboratories, 33 Fukumi-ku, Kyoto, Japan F-term (reference) 4K057 DA20 DB01 DB03 DC10 DD01 DM05 DM14 DN02 5F004 BA20 BB13 DA04 DA23 DB08 DB13 EB02 5F045 AA08 BB08 BB14 DP02 EB02 EH03 EH04 EH12 EH20

Claims (3)

[Claims] A processing chamber for storing an etching target containing metal atoms; a dielectric window provided in the processing chamber for introducing high-frequency power into the processing chamber; and a dielectric window disposed behind the dielectric window. An inductively coupled plasma processing apparatus comprising a coil electrode, and a high-frequency power supply for applying a high-frequency voltage to the coil electrode, wherein the metal atoms scattered from the object to be processed during the etching process are disposed in the dielectric window. The geometric shape of the metal film attached to the surface facing the inside of the processing chamber and formed on the surface is such that the flow of current induced in the metal film by the action of the high-frequency magnetic field generated by the coil electrode is interrupted on the way. An inductively coupled plasma processing apparatus, comprising: a mask member for concealing a part of the surface of the dielectric window so as to have a shape as shown in FIG. 2. A method according to claim 1, wherein the mask member is formed by forming a slit extending in the member covering the surface of the dielectric window facing the inside of the processing chamber so as to intersect the winding direction of the coil electrode. The inductively coupled plasma processing apparatus according to claim 1, wherein: 3. The inductively coupled plasma processing apparatus according to claim 2, wherein the mask member is arranged at a minute interval from the dielectric window.