JP7224621B2 - Anti-adhesion plate for inductively coupled plasma processing equipment - Google Patents

Description

The present invention relates to an anti-adhesion plate for an inductively coupled plasma processing apparatus.

2. Description of the Related Art A sputter etching method has been conventionally known as a method for performing fine processing on the surface of an object to be processed. In this method, an object to be processed having a processing pattern mask formed on the surface to be processed is placed in an airtight processing chamber, and a processing gas (Ar, Cl _{2 ,} etc.) is introduced into the processing chamber while maintaining the processing chamber at a low pressure. is supplied to generate a high-frequency electromagnetic field in the processing chamber, thereby plasmatizing the processing gas. Ions contained in this plasma are accelerated by a bias voltage and made to collide with the surface to be processed of the object to be processed, thereby scraping off the unmasked portion of the surface to be processed.

An inductively coupled plasma (ICP) processing apparatus is known as one of the apparatuses for performing the above processing. An ICP processing apparatus generally includes a processing chamber for performing plasma processing on an object to be processed, a coil electrode provided outside the processing chamber for supplying high-frequency power for plasma generation to the processing chamber, and a coil electrode generated by the coil electrode. A window serving as an electromagnetic field introduction port for introducing the generated high frequency electromagnetic field into the processing chamber, and a high frequency power supply for applying a high frequency voltage to the coil electrode are provided. Since the window must pass high-frequency electromagnetic fields, it is generally made of a dielectric such as quartz and is called a dielectric window.

In microfabrication using ICP processing equipment, substrates, thin films, etc. containing metals (e.g., platinum (Pt), iridium (Ir), nickel (Ni)) or metal oxides (e.g., iridium oxide, tin oxide, etc.) It is often used as an object to be processed. When a large number of such metal-based processing objects (processing objects containing metal atoms) are processed for a long period of time, the metal sputtered by plasma ions and scattered from the processing objects gradually adheres to the surface of the dielectric window. and a conductive film is formed there. When the conductive film is formed on the surface of the dielectric window in this way, an induced current is induced in the conductive film by the magnetic field of the high-frequency electromagnetic field generated by the coil electrode, and high-frequency power is consumed by this induced current. Therefore, the supply of high-frequency power to the processing chamber is hindered.

Therefore, a second dielectric plate, which is easy to attach and detach, is provided under the dielectric window (first dielectric plate) (on the side of the object to be processed) so that the scattered matter from the object to be processed adheres to that side. After that, a method of shortening the maintenance time by replacing it has been devised (Patent Document 1).

In order to lengthen the exchange time (period), a disc-shaped plate having approximately the same size as the dielectric window is used as the anti-adhesion plate (corresponding to the second dielectric plate) provided under the dielectric window. A configuration has been devised in which linear slits extending radially from the center of a member are formed (Patent Document 2). In the case of an ICP processing apparatus, the coil electrode is usually installed so that its central axis is perpendicular to the dielectric window, so the induced current generated in the conductive film formed on the surface of the dielectric window, etc. flow in the direction approximately along the winding of the Therefore, by forming linear slits radially extending from the center of the deposition prevention plate, an induced current is generated in both the deposition prevention plate and the conductive film formed on the lower surface of the dielectric window. can be prevented.

Japanese Patent Application Laid-Open No. 2000-068252 JP-A-2001-254188

By providing the anti-adhesion plate as described above, it is possible to prevent an induced current from being generated in the dielectric window, and to continue supplying high-frequency power from the coil electrode to the processing chamber for a long period of time.

However, the problem caused by the adhesion of the conductive film is not limited to the problem of attenuation of high-frequency power, but also the conductive objects (often in the form of small particles) formed by adhesion to the dielectric window. ) peels off and falls onto the workpiece. Attenuation of high-frequency power leads to a decrease in processing efficiency, but has little effect on product quality. However, if the dropped particles or the like adhere to the object to be processed, the object to be processed becomes a defective product. In the case of a semiconductor device or the like in which many products are manufactured from one processing object, the influence is great.

The present invention has been made to solve such problems, and its object is to prevent the conductive particles formed on the surface of the dielectric window from dropping as much as possible.

The present invention, which has been made to solve the above problems, comprises a processing chamber having a workpiece mounting table, a coil electrode arranged outside the processing chamber for generating a high-frequency electromagnetic field, and the workpiece mounting table. In an inductively coupled plasma processing apparatus comprising a dielectric window provided between the coil electrodes,
A plate provided between the dielectric window and the workpiece mounting table, the plate having a substrate and a particle capturing layer provided on a surface of the substrate on the workpiece mounting table side, wherein the coil It is characterized by comprising an anti-adhesion plate having a slit for blocking an induced current induced by the electrode.

The inductively coupled plasma processing apparatus according to the present invention includes an anti-adhesion plate between the dielectric window and the workpiece mounting table. Alternatively, if the substrate is provided with a conductive layer, a slit is provided to block the induced current induced by the coil electrode. This anti-adhesion plate has a substrate and a particle capturing layer provided on the surface of the substrate on the workpiece mounting table side.

The substrate should be made of metal, ceramic, glass, quartz, or the like, which is easy to handle during replacement and has sufficient rigidity so as not to deform due to heat during plasma processing. is desirable.

The particle trapping layer is made of a material that does not easily peel off once the scattered matter released from the object to be processed adheres to it. For example, if the object to be processed is mainly made of silicon and it is assumed that silicon will mainly adhere, a metal such as nickel, chromium, or titanium, which has a hardness lower than that of silicon, is used as the particle trapping layer. be able to. It is preferable that the particle trapping layer is formed by laminating two or more layers of different metals in order to increase the adhesion strength to the substrate. For example, when the substrate is quartz, it is preferable to laminate nickel or chromium, which has high adhesion strength to quartz, and then laminate nickel. On the other hand, when the object to be processed is mainly made of metal, the particle trapping layer is made of a metal of the same kind as the object to be processed, or a metal with a lower hardness than the metal of the object to be processed even if it is of a different kind. It is desirable to If a metal is used as the particle trapping layer, the substrate can also be the same metal. That is, in this case, the substrate and the particle trapping layer are integrally formed, and the attachment prevention plate can be configured as a single metal plate having slits. The same applies to the case of using other materials as the raw material. In order to trap particles made of various materials such as compound semiconductors such as indium phosphide (InP), gallium arsenide (GaAs), gallium nitride (GaN), or silicon carbide (SiC), the trapping layer is made of resin. However, in this case, if the entire anti-adhesion plate is made of resin, there may be a problem with strength (especially strength at high temperatures), so the substrate should be made of quartz, metal, ceramic, etc. should be used.

When the particle trapping layer is made of metal, it can be formed by a plating method, a vacuum deposition method, or a sputtering method. On the other hand, when the particle trapping layer is made of resin, it is convenient to form it by coating.

In the inductively coupled plasma processing apparatus according to the present invention, when an object to be processed containing metal atoms is placed on the object mounting table and subjected to plasma treatment, a substance containing metal atoms scatters from the object to be processed, Also head towards the dielectric window. However, in the inductively coupled plasma processing apparatus according to the present invention, since the anti-adhesion plate is provided between the workpiece mounting table and the dielectric window, a substance containing metal atoms adheres to the dielectric window, making it conductive. It rarely forms a film.

The substance containing metal atoms scattered from the object to be processed mainly adheres to the surface of the anti-adhesion plate on the side of the object mounting table. However, since this attachment prevention plate is provided with a slit that blocks the induced current induced by the coil electrode, no induced current is generated in the attachment prevention plate either. As a result, in the inductively coupled plasma processing apparatus according to the present invention, high-frequency power that is not attenuated can be continuously introduced into the processing chamber over a long period of time.

In addition, since a particle capture layer is provided on the surface of the anti-adhesion plate on the side of the work piece mounting table, substances containing metal atoms scattered from the work object can be removed compared to the conventional dielectric anti-adhesion plate. As a result, it adheres more strongly to this anti-adhesion plate and is captured. Therefore, it is less likely that substances containing metal atoms will peel off from the anti-adhesion plate, fall off, and adhere to the workpiece as particles.

The anti-adhesion plate is formed in consideration of the shape of the dielectric window (and the coil electrode). For example, when the dielectric window is disc-shaped, the anti-adhesion plate is a disc having approximately the same size as the dielectric window, and a plurality of anti-adhesion plates radially extending from the center of the disc (that is, the central axis of the coil electrode). can be formed with slits.

When this deposition-preventing plate 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 formed on the lower surface of the deposition-preventing plate (surface on the workpiece side) is Short-circuiting between the film and the metal film deposited on the underside of the dielectric window may result in loss of the induced current blocking action described above. In order to prevent such a situation, it is preferable to dispose the anti-adhesion plate at a minute distance from the dielectric window. By doing so, the insulation between the anti-adhesion plate and the dielectric window becomes more reliable. If the gap is too small, the edge of the metal film formed on the lower surface of the dielectric window may block the gap between the anti-adhesion plate and the dielectric window. If the thickness is too large, the metal atoms passing through the slit may reach the rear surface of the deposition-inhibiting plate and adhere to the lower surface of the dielectric window. Such a problem can be solved, for example, by setting the distance between the anti-adhesion plate and the dielectric window to 0.1 to 0.5 mm.

When the attachment-preventing plate has the above configuration, the plurality of slits are arranged in a radial spiral shape with respect to the central axis of the coil electrode, and none of the slits are positioned on the same straight line as other slits. is desirable.

The form of the attachment-preventing plate is not limited to having slits as described above. For example, even if a star-shaped (asterisk-shaped) anti-adhesion plate having a plurality of arms radially extending outward from the center is used, the induced current blocking effect as described above can be obtained.

In addition, when the dielectric window is cylindrical or bell-shaped, a substantially cylindrical anti-adhesion plate is prepared so as to hide the inner wall surface of the dielectric window, and the anti-adhesion plate is provided with multiple By providing the slit, it is possible to prevent the generation of an induced current along the winding of the coil electrode.

When an object to be processed containing metal atoms is plasma-processed in the inductively coupled plasma processing apparatus according to the present invention, the substance containing metal atoms scatters from the object to be processed and travels toward the dielectric window. However, in the inductively coupled plasma processing apparatus according to the present invention, the anti-adhesion plate is provided between the workpiece mounting table (that is, the workpiece placed thereon) and the dielectric window. It is rare for a substance containing metal atoms to adhere to the surface of the substrate to form a conductive film.

The substance containing metal atoms scattered from the object to be processed mainly adheres to the surface of the anti-adhesion plate on the side of the object mounting table. However, since this attachment prevention plate is provided with a slit that blocks the induced current induced by the coil electrode, no induced current is generated in the attachment prevention plate either. As a result, in the inductively coupled plasma processing apparatus according to the present invention, high-frequency power that is not attenuated can be continuously introduced into the processing chamber over a long period of time.

In addition, since a particle trapping layer is provided on the surface of the anti-adhesion plate on the side of the work piece mounting table, substances including metal atoms scattered from the work object are prevented from Comparatively, it adheres more strongly to this particle trapping layer. Therefore, it is less likely that substances containing metal atoms or the like are peeled off from the adhesion-preventing plate, fall off, and adhere to the workpiece as particles.

1 is a schematic configuration diagram of an ICP processing apparatus embodying the present invention; FIG. FIG. 1(a) is a bottom view of the first form of the anti-adhesion plate of the ICP processing apparatus, (b) is a sectional view taken along the line IIb-IIb, and (c) is an enlarged view of the portion IIc. FIG. 5 is an explanatory diagram illustrating the process of forming a metal film on the surface of a dielectric window and the surface of a deposition-preventing plate when a plasma etching process is performed on an object to be processed in an ICP processing apparatus; (b) is an ICP processing apparatus according to an embodiment of the present invention, and (c) is an enlarged view of the portion IIIc of (b). The figure (a) which looked at the thing of the 2nd form of the attachment-proof board from the bottom, and the enlarged view (b) of the attachment part. The figure which looked at the thing of the 3rd form of the attachment-proof board from the bottom. The figure which looked at the thing of the 4th form of the attachment-proof board from the bottom. The figure which looked at the thing of the 5th form of the attachment-proof board from the bottom.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of an ICP processing apparatus embodying the present invention. This ICP processing apparatus 1 has a sealable processing chamber 20 in which a workpiece 10 is housed. A processing gas passage 21 is connected to the upper portion of the processing chamber 20 , through which gas for plasma etching processing is supplied from a processing gas supply section 22 into the processing chamber 20 . The pressure inside the processing chamber 20 is controlled to a low pressure by a pressure control mechanism including a rotary pump (RP) 31, a turbomolecular pump (TMP) 32, a valve 33 and a pressure controller .

A lower electrode 23 for placing the workpiece 10 is provided in the lower part of the processing chamber 20 . The bottom electrode 23 is connected through a first matching circuit 35 to a first radio frequency (RF) generator 36 . The first RF generator 36 applies a bias voltage to the lower electrode 23 for accelerating plasma ions generated within the processing chamber 20 toward the workpiece 10 . This lower electrode 23 corresponds to the workpiece mounting table of the present invention.

A circular window plate receiving portion 202 having an opening is provided on the upper wall surface (ceiling) 201 of the processing chamber 20, and a disk-shaped window plate 25 made of a dielectric material is placed therein. The window plate receiving portion 202 is set so that the center of the window plate 25 attached thereto substantially coincides with the center of the lower electrode 23 . The inner surface of the window plate 25 (the surface facing the workpiece 10) is covered with an exchange plate 27 (FIG. 2(b)), and an anti-adhesion plate 50 is attached to the lower surface of the exchange plate 27. As shown in FIG. A combination of the window plate 25 and the exchange plate 27 corresponds to the dielectric window of the present invention. While the window plate 25 is used for a long period of time while being attached to the processing chamber 20, the replacement plate 27 is replaced together with the anti-adhesion plate 50 in an appropriate period shorter than that, so it is cheaper than the window plate 25. and is easy to replace. The anti-adhesion plate 50 will be described later.

A spiral coil electrode 26 is arranged on the upper surface of the window plate 25 . The coil electrode 26 is arranged such that its central axis is substantially perpendicular to the window plate 25 and substantially coincides with its center. Therefore, the central axis of the coil electrode 26 passes through substantially the center of the lower electrode 23 . The coil electrode 26 is connected through a second matching circuit 37 to a second RF generator 38 . The second RF generator 38 applies a high frequency voltage to the coil electrodes 26 to generate a high frequency magnetic field from the coil electrodes 26 .

The structure of the anti-adhesion plate 50 is shown in FIG. In FIG. 2, (a) shows the anti-adhesion plate 50 viewed from inside the processing chamber 20 (from the side of the workpiece 10). (b) shows a cross section of the anti-adhesion plate 50 taken along line IIb-IIb in (a) (both sides are omitted), and (c) is an enlarged view of the IIc portion. A ring-shaped anti-adhesion plate support 52 is fixed by a plurality of screws 51 around a circular opening 203 formed in the window plate receiving portion 202 , and the anti-adhesion plate 50 is supported by this anti-adhesion plate support 52 . , are fixed under the exchange plate 27 . A stepped portion 501 is formed along the circumference of the upper surface of the attachment-preventing plate 50 (the surface that faces the replacement plate 27 when properly attached). A gap 502 is formed. A plurality of linear slits 503 extending radially from the center are formed inside the stepped portion 501 of the attachment-preventing plate 50 .

In this embodiment, the main body (substrate) of the adhesion-preventing plate 50 is made of quartz, ceramic, or metal, and the lower surface (the surface facing the workpiece 10 when properly attached) is plated with a metal layer. 505, or a resin layer 505 is provided. Alumina, silicon nitride, silicon carbide, and quartz can be used as the ceramic material for the main body of the adhesion-preventing plate 50, and aluminum, stainless steel, or the same material as the metal layer 505 described later can be used as the metal. can be done. Nickel (Ni), chromium (Cr), titanium (Ti), etc. can be used as the material of the metal layer 505, and polyimide resin, polyetheretherketone resin (PEEK), etc. can be used as the material of the resin layer 505. can be used. The metal layer 505 can be formed on the lower surface of the main body (substrate) by plating, vapor deposition, or the like. The resin layer 505 can be provided by applying resin to the lower surface of the main body (substrate) and then curing the resin.

In addition, the anti-adhesion plate can also be made entirely of metal. In this case, the surface of the lower surface of the anti-adhesion plate itself serves as the particle trapping layer of the present invention.

In the ICP processing apparatus of the present embodiment, when performing plasma etching processing on the workpiece 10 containing a substance made of metal or metal oxide (that is, containing metal atoms), a dielectric window accompanying the progress of processing (more specifically, the surface of the exchange plate 27) and the surface of the adhesion preventing plate 50 will be described with reference to FIGS. 3(a) and 3(b). FIG. 3(c) is an enlarged view of the portion IIIc of (b).

When high frequency power (RF) is supplied into the processing chamber 20 from the coil electrode 26 through the window plate 25 and the exchange plate 27, the processing gas in the processing chamber 20 is turned into plasma. Ions contained in this plasma are accelerated by the electric field generated by the bias voltage applied to the lower electrode 23 and collide with the upper surface of the workpiece 10 . Due to this ion bombardment, the metal or metal oxide is scraped off from the upper surface of the workpiece 10 and scattered into the processing chamber 20 (sputtering, FIG. 3(a)). Some of the sputtered metal atoms and the like are gradually deposited on the lower surface of the anti-adhesion plate 50 to form the metal film 551 , but the metal atoms and the like are not deposited on the slit 503 . As a result, the metal film 551 has a circular shape in which a plurality of slit-like holes are radially opened. On the other hand, other parts of the sputtered metal atoms pass through the slits 503 of the attachment-preventing plate 50 and reach the exchange plate 27, where they form a metal film 552 having substantially the same shape and dimensions as the slits 503. (Fig. 3(b) and (c)). In this way, since the metal films 551 and 552 are separately formed on the surfaces of the anti-adhesion plate 50 and the exchange plate 27, no induced current is generated along the winding direction of the coil electrode 26, and the high frequency Supplying the power RF into the processing chamber 20 is not difficult.

In addition, since the metal layer 505 or the resin layer 505 is provided on the lower surface of the anti-adhesion plate 50, metal atoms or metal oxides sputtered from the workpiece 10 and gradually deposited on the lower surface of the anti-adhesion plate 50 are , and adheres to the metal layer 505 or the resin layer 505 on the lower surface of the adhesion-preventing plate 50 with a high adhesive force, so that it does not peel off. Therefore, the workpiece 10 is prevented from being contaminated by particles falling from the anti-adhesion plate 50 .

FIGS. 4(a) and 4(b) are diagrams showing another form of the anti-adhesion plate. The anti-adhesion plate 60 of FIG. 4 has an asterisk shape consisting of eight arms 601 extending radially outward from the center. A stepped portion 603 is formed on the rear surface (upper surface) of the tip of each arm 601 , thereby forming a gap 602 between the attachment prevention plate 60 and the replacement plate 27 . The main body of the anti-adhesion plate 60 is also made of quartz, and a metal layer 605 is formed on the lower surface by plating or vapor deposition, or a resin layer 505 is formed by coating. Even if such an anti-adhesion plate 60 is used, the same effects as obtained with the anti-adhesion plate 50 can be obtained.

Figs. 5 to 7 show still another form of the anti-adhesion plate. The anti-adhesion plate 70 of FIG. 5 and the anti-adhesion plate 80 of FIG. are arranged so as not to be positioned on the same straight line as the slits 71 and 81 of . By doing so, it is possible to prevent stress from concentrating on the main body portion between the ends of the slits 71 and 81 and to suppress the occurrence of cracks from the ends of the slits 71 and 81 . Also, even if cracks occur at the ends of the slits 71 and 81, the cracks are unlikely to be combined with cracks occurring at the ends of the other slits 71 and 81, resulting in significant damage to the anti-adhesion plates 70 and 80. can be suppressed. The adhesion-preventing plate 90 of FIG. 7 has nine slits 91 arranged radially in a regular nine-sided shape. Such an arrangement of slits can also provide the above effects. Of course, such a configuration can be generalized to other regular polygons by setting the number n of slits to an odd number of 3 or more. A metal layer or a resin layer as described above is also provided on the bottom surface of each of the anti-adhesion plates 70 , 80 , 90 .

DESCRIPTION OF SYMBOLS 1... ICP processing apparatus 10... Object to be processed 20... Processing chamber 23... Lower electrode 25... Window plate 26... Coil electrode 27... Replacement plate 50... Anti-adhesion plate 501... Stepped portion 502... Gap 503... Slit 505... Metal layer, Resin layer 52 Anti-adhesion plate support 551 Metal film 552 Metal films 60, 70, 80, 90 Anti-adhesion plates 71, 81, 91 Slits

Claims (8)

A processing chamber having a processing object mounting table on which a processing object containing metal atoms is mounted, a coil electrode arranged outside the processing chamber and generating a high-frequency electromagnetic field, the processing object mounting table and the In an inductively coupled plasma processing apparatus comprising a dielectric window provided between coil electrodes,
A plate provided between the dielectric window and the workpiece mounting table, the plate having a substrate and a particle capturing layer provided on a surface of the substrate on the workpiece mounting table side, wherein the coil Equipped with an anti-adhesion plate having a slit that blocks an induced current induced by the electrode,
1. An inductively coupled plasma processing apparatus, wherein said particle trapping layer is a metal layer of the same kind as metal atoms contained in said object to be processed . 2. An inductively coupled plasma processing apparatus according to claim 1, wherein said substrate is made of quartz, ceramic or metal. The substrate is made of quartz,
3. The inductive coupling type according to claim 1, wherein the particle trapping layer is a laminate of two or more metal layers, and the substrate side of the particle trapping layer is a metal layer of nickel or chromium. Plasma processing equipment. 3. The anti-adhesion plate is a plate made of the same metal as the metal atoms contained in the object, wherein the substrate and the particle trapping layer are integrally formed. The inductively coupled plasma processing apparatus according to 1. 4. The inductive coupling according to any one of claims 1 to 3, wherein the particle capturing layer is a deposited film, a sputtered film, or a plated film provided on the surface of the substrate on the workpiece mounting table side. type plasma processing equipment. 6. The inductively coupled plasma processing apparatus according to any one of claims 1 to 5 , characterized in that said anti-adhesion plate is arranged at a minute distance from said dielectric window. 7. The anti-adhesion plate according to any one of claims 1 to 6 , wherein the plate has the same shape as the dielectric window and has a plurality of slits extending radially from the central axis of the coil electrode. The inductively coupled plasma processing apparatus according to 1. The anti-adhesion plate has a plurality of slits arranged radially spirally with respect to the central axis of the coil electrode in a plate having the same shape as the dielectric window, and all the slits are on the same straight line as the other slits. 8. The inductively coupled plasma processing apparatus according to any one of claims 1 to 7 , wherein the inductively coupled plasma processing apparatus is configured so as not to be positioned at

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