JPH11214366A - Plasma treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make abnormal discharges hard to be generated in an electrode. SOLUTION: This plasma treatment device is constituted to have an electrode 10 for mounting a treatment object 1 facing a plasma space and insulator layers 12 to 15 provided to be interposed with a buffer layer 110 with respect to the electrode 10. A conductive adhesive is added to the buffer layer 110. A conductors 111 is embedded in the buffer layer 110. Thereby, the capacity between the electrode 10 and the object to be theated 1 increases and even application of a low voltage to the electrode 10 is sufficient so that abnormal discharges becomes hardly generated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a plasma processing apparatus (plasma reactor) such as a plasma etching apparatus and a plasma film forming apparatus, and relates to an IC (semiconductor device).
The present invention relates to a plasma processing apparatus suitable for performing a plasma process, that is, a process based on a plasma reaction on a substrate or the like in a high-precision manufacturing process such as an LCD, a liquid crystal display panel (LCD), or a plasma display panel (PDP). More specifically, the present invention relates to an improvement in an electrode on which an object to be processed is mounted during plasma processing.

[0002]

2. Description of the Related Art As a typical example of a plasma processing apparatus, an etching apparatus whose schematic structure is shown in FIG. 4 forms a plasma space between a pair of parallel flat plates serving as counter electrodes and forms a substrate (such as a silicon wafer). This is a so-called parallel plate etcher (RIE) for performing an etching process (plasma process) on the object to be processed. In such a parallel plate type plasma processing apparatus, a pair of parallel plates 3 and 10 are provided in vacuum chambers 4 and 5 in a line up and down or left and right, and a plasma formed between the two plates 3 and 10 is provided. Plasma 2 in space
Is generated or introduced, and a predetermined processing gas A or the like is also introduced into the plasma space (2). Then, a plasma reaction is performed in the plasma space (2), whereby the surface of the substrate 1 in the plasma space (2) is subjected to an etching process.

In this case, an openable / closable vacuum chamber lid 5 is attached to the upper part of the open box-shaped vacuum chamber main body 4 in order to secure a vacuum state necessary for maintaining plasma. And a vacuum pump 7 such as a turbo pump provided with a variable valve 6 for controlling vacuum pressure
Is connected. In addition, in order to excite the plasma 2 or to enhance the anisotropy of the plasma processing, the cathode capacitor 10 serving as an electrode on which an object to be processed is mounted during the plasma processing among the counter electrodes facing the plasma space is provided with a blocking capacitor. The RF power supply 9 is connected via the power supply 8. RF power supply 9
Of these, a variable output power with a frequency of 500 KHz to 2 MHz is often used, and an alternating electric field is applied to the grounded anode unit 3 and a bias voltage is generated.

[0004]

2. Description of the Related Art In order to increase a bias voltage applied to the wafer 1, such a cathode section 10, that is, an electrode for mounting an object to be processed, has a buffer layer and an insulating layer on the surface of the electrode on which the object is to be mounted. A body layer is laminated, and at that time, a buffer layer is used as an intermediate layer and an insulator layer is used as an upper layer, and a layered conductor is embedded in the insulator layer. FIG. 5 shows a vertical cross-sectional structure diagram of such an electrode. In this drawing, a portion of the cathode portion 10 stacked on the upper surface is particularly enlarged in the vertical direction to clearly show the layer structure. .

[0005] An adhesive 11,
The insulator film 12, the adhesive 13, the metal film 14, and the insulator film 15 are sequentially stacked in layers, and when the wafer 1 is placed on the cathode unit 10, the wafer 1 is not directly placed on the cathode unit 10 but on a laminate thereof. Ride indirectly through. The layer of the metal film 14 is buried between the adhesive 13 and the insulator film 15 so that the spread is suppressed to a range narrower than the spread of the other layers.

The cathode portion 10 is a plate, tube or rod made of a metal such as aluminum.
The first layer has a thickness of about 80 μm made of a non-conductive adhesive such as an epoxy-based adhesive, and the layer of the insulator film 12 has a thickness of about 25 μm made of an insulator such as polyimide. The layer of the adhesive 13 is made of a non-conductive adhesive such as an epoxy-based adhesive and has a thickness of about 20 μm.
The layer 4 is made of a good conductor such as copper and has a thickness of about 5 to 20 μm, and the layer of the insulator film 15 is made of an insulator such as polyimide and has a thickness of about 50 μm or an insulator such as alumina ceramic. It has a thickness of about 300 μm. Then, of these, the layer of the adhesive 11 serves as a buffer layer, and the multilayer portion from the insulator film 12 to the insulator film 15
It is an insulator layer in which a conductor is embedded.

In order to form such an insulator layer, a metal film 14 is applied to a predetermined area of one surface of the insulator film 15 by sputtering or the like, and then an adhesive 13 is applied thereon. At the same time, the insulating film 12 is attached and sandwiched by a parallel holding tool or the like until the adhesive 13 is hardened so that the thickness becomes constant. Then, an unnecessary peripheral portion is cut off while leaving a place having a size suitable for the workpiece mounting surface of the cathode portion 10. In this manner, when the insulator layers 12 to 15 in which the conductors 14 are embedded are completed, the adhesive 11 is applied to the surface of the cathode portion 10 on which the workpiece is mounted, and the insulator film 12 is placed thereon. Layer 1
2 to 15 are placed, and the positions of the insulator layers 12 to 15 are made to coincide with the processing object mounting surface of the cathode portion 10, and then pressed with a flat jig so that the thickness of the adhesive 11 becomes constant. . The protruding portion of the adhesive 11 is removed after the adhesive 11 has hardened.

In this manner, the cathode section 10 is
Are interposed, and the insulator layers 12 to 15 are laminated, and further housed in the vacuum chamber main body 4 and subjected to plasma processing. At this time, each member in the vacuum chamber thermally expands due to heat generated by the plasma processing, and the insulating layers 12 to 15 having different coefficients of thermal expansion and the cathode section 10 have different thermal expansion methods. If there is no undesired force, an undesired deformation force or a force for peeling off is applied to the relatively thin insulator layers 12 to 15, whereas the presence of the buffer layer 11 reduces such force. Impact is mitigated.

When a high frequency is applied from the RF power supply 9 to the cathode section 10, a bias voltage determined based on the dielectric constant and thickness of each of the above members is applied to the wafer 1.
Is also applied. Specifically, assuming that the dielectric constants of the adhesives 11 and 13 and the insulator films 12 and 15 are substantially the same, the wafer 1
400 kHz to apply the desired bias voltage to
When a high frequency of z is supplied at a power of 300 W, the cathode section 10 has a peak-to-peak (Vpp) of about 3000 V
Will be applied.

[0010]

In such a conventional plasma processing apparatus, an insulator layer is bonded to an electrode in order to apply a bias voltage to an object to be processed. Since it also serves as a buffer layer for alleviating the difference in thermal expansion between the two, the thickness is made thicker than merely bonding. For this reason, the capacity between the electrode and the object to be processed, which is determined depending on the insulator layer and the buffer layer, is smaller than that without the buffer layer. And if this capacity is small,
In order to apply a desired bias voltage to an object to be processed, the voltage applied to the electrode must be increased.

However, when the voltage applied to the electrode is high, abnormal discharge related to the electrode is likely to occur. When abnormal discharge occurs, the plasma is disturbed, and the plasma processing is impaired. For this reason, we want to keep the voltage applied to the electrodes as low as possible.However, it is difficult to make the insulator layer and buffer layer thinner than this, and it is also difficult to use another member with a high dielectric constant in those places. It is still difficult from the viewpoint of properties and adhesion. Therefore, it is necessary to improve the capacity of the buffer layer and the like while following the conventional thickness and material of the buffer layer and the like.

The present invention has been made to solve such a problem, and has as its object to realize a plasma processing apparatus in which abnormal discharge is unlikely to occur in electrodes.

[0013]

Means for Solving the Problems First to third solving means invented to solve such problems are as follows.
The configuration and operation and effect will be described below.

[First Solution] A plasma processing apparatus according to a first solution (as described in claim 1 at the beginning of the application) comprises: an electrode for mounting an object to be processed facing a plasma space; In contrast, the present invention provides a plasma processing apparatus comprising an insulating layer provided with a buffer layer interposed therebetween, wherein the buffer layer contains a conductive adhesive. That is, an electrode in which an insulator layer (with the first conductor embedded in a layer or without such a conductor) is laminated via a buffer layer (consisting of a slightly thicker adhesive layer);
In a plasma processing apparatus for performing a plasma process by mounting an object to be processed on the electrode, a conductive adhesive is used in at least a central portion of the buffer layer.

In the plasma processing apparatus of the first solution, the buffer layer which has become conductive from insulating functions electrically as an electrode extension instead of an insulator layer. Since the capacitance between the electrode and the object to be processed is determined based not on the thickness of the buffer layer and the insulator layer but on the basis of only the thickness of the insulator layer, the capacitance between the buffer layer and the object to be processed is determined. Equals or approaches the capacity of

As a result, the substantial capacitance between the electrode and the object to be processed is increased, and the bias voltage is sufficient even if the voltage directly applied to the electrode is low, so that abnormal discharge related to the electrode occurs. It becomes difficult. Therefore, according to the present invention, it is possible to realize a plasma processing apparatus in which abnormal discharge hardly occurs in the electrodes.

[Second Solution] The plasma processing apparatus according to the second solution (as described in claim 2 at the beginning of the application) is the plasma processing apparatus according to the first solution, wherein It is characterized in that the (also second) conductor is embedded (again in a layered form) at the buffer layer.

Here, "embedded at the buffer layer" means that the condition is applicable if the semiconductor device is embedded in the buffer layer. For example, if it is embedded only by the member used for the buffer layer, it is of course applicable,
It is not necessary to be embedded only by the member used for the buffer layer, and it is applicable even if embedded by the member used for the buffer layer and another adjacent member.

In the plasma processing apparatus of the second solution, since the electric potential is made uniform at the conductor, the conductivity is unstable or non-uniform depending on the situation when the adhesive is solidified. Even if the potential distribution becomes uneven at the conductive adhesive of the buffer layer, which tends to become uneven, the unevenness is canceled by the presence of the conductor. Thereby, the conductive adhesive can be used for the buffer layer without worrying about the situation at the time of solidification and the like, so that the performance is stabilized and the manufacturing process is facilitated. Therefore, according to the present invention, it is possible to easily realize a plasma processing apparatus in which abnormal discharge hardly occurs in the electrodes.

[Third Solution] The plasma processing apparatus of the third solution (as described in claim 3 at the beginning of the application) is the plasma processing apparatus of the first and second solutions. Further, a non-conductive member is disposed on a peripheral portion of the buffer layer.

In the plasma processing apparatus according to the third solution, even if the central portion of the buffer layer electrically functions as an extension of the electrode, the peripheral portion of the buffer layer can be used. Since still functions as an extension of the insulator layer, the state in which an abnormal discharge hardly occurs on the outer surface of the buffer layer is maintained without being damaged. This eliminates a factor that reduces the effect of suppressing the abnormal discharge based on the increase in the capacity between the electrode and the object to be processed, so that the effect of suppressing the discharge can be surely enjoyed. Therefore, according to the present invention, it is possible to realize a plasma processing apparatus in which abnormal discharge is less likely to occur in the electrodes.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the plasma processing apparatus of the present invention achieved by such a solution will be described in the first to first embodiments.
This will be described more specifically with reference to a third embodiment.
The present invention embodies the first and second solving means described above,
The second and third embodiments also embody the third solution means described above. Note that what has been described in the background art is common to any of the embodiments, so that the description thereof will not be repeated, and the following description will focus on differences from the conventional example.

[0023]

First Embodiment A first embodiment of the plasma processing apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional structural view of the electrode, and corresponds to FIG. 5 in the conventional example. This plasma processing apparatus is different from the conventional apparatus in that the non-conductive adhesive 1
1 in that a conductive adhesive 110 is used for the buffer layer, and a metal film 111 is newly provided in a central portion of a boundary surface between the insulator film 12 and the adhesive 110. It is.

The buffer layer made of the adhesive 110 has a thickness of about 80 μm as in the past, but exhibits conductivity due to the carbon powder and silver paste mixed into the adhesive 11. The layer of the metal film 111 is made of a good conductor such as copper like the metal film 14 and has a thickness of about 5 to 20 μm.
Before the insulating film 12 is attached to the insulating film 15, the insulating film 12 is formed by previously applying a predetermined area on one surface of the insulating film 12 by sputtering or the like.

As a result, the buffer layer interposed between the electrode and the insulator layer contains the conductive adhesive not only in the center but also in the entire area. The second conductor is embedded.

When such a plasma processing apparatus is operated, an undesired deformation force applied to the insulator layers 12 to 15 and the cathode section 10 with respect to the insulator layers 12 to 15 and the cathode portion 10 having different coefficients of thermal expansion or peeling may occur. Is reduced by the presence of the buffer layer 11. In this way, the function of the buffer layer, ie the buffer function and the adhesive function, is maintained as before without any loss.

When a high frequency is applied from the RF power supply 9 to the cathode section 10, a bias voltage determined based on the dielectric constant and thickness of each of the above members is applied to the wafer 1.
Is also applied. Specifically, based on the thicknesses of the insulator film 12, the adhesive 13, and the insulator film 15 excluding the adhesive 111, the capacitance between the cathode unit 10 and the wafer 1 becomes the thickness of the adhesive 11. (80 + 2
5 + 20 + 50) / (25 + 20 + 50)).

Therefore, a high frequency of 400 kHz is set to 3
In the case of supplying with a power of 00 W, in order to apply a desired bias voltage to the wafer 1, it is sufficient to apply a voltage of about 1600 V peak-to-peak (Vpp) to the cathode portion 10. Thus, the plasma processing can be performed on the wafer 1 with the voltage applied to the cathode unit 10 kept lower than in the past.

[0029]

Second Embodiment A plasma processing apparatus according to a second embodiment of the present invention whose longitudinal sectional structure is shown in FIG. 2 is different from that of the first embodiment in that the conductive adhesive 110 is used. The non-conductive adhesive 113 is used at the peripheral portion of the buffer layer while the range is reduced to the central portion of the buffer layer.
0 in that the escape groove 112 is formed on the upper surface.
As the adhesive 113, the same as the adhesive 11 is used. Thus, the buffer layer interposed between the electrode and the insulator layer includes a conductive adhesive and a conductor in a central portion thereof, and a non-conductive member is disposed in a peripheral portion thereof. It has become.

The relief groove 112 is formed by engraving the buffer layer into an annular or rectangular shape corresponding to the boundary between the center and the edge. Then, an adhesive 110 and an adhesive 113 are applied to the upper surface of the cathode portion 10 and then the insulating layers 12 to
The adhesive which is pushed when the 15 is attached to the cathode portion 10 and overflows is poured and released.

In the case of such a plasma processing apparatus, RF
Even when a high frequency is applied from the power supply 9 to the cathode unit 10 and the potential of the cathode unit 10 fluctuates greatly at that time, the potential of the adhesive 110 and the metal film 111 also changes greatly, the potential of the adhesive 113 remains unchanged. , Because they are insulated from them, they do not change much. Thus, even if a high voltage is applied to the central portion of the buffer layer, that is, the inside of the buffer layer except for the peripheral portion, only a lower voltage needs to be applied to the outer surface of the buffer layer related to the abnormal discharge. .

[0032]

Third Embodiment A plasma processing apparatus according to a third embodiment of the present invention whose longitudinal sectional structure is shown in FIG. 3 is different from that of the second embodiment in that the edge portion of the buffer layer is different. Is that an insulator film 114 is placed instead of the adhesive 113 in FIG. The insulator film 114 is formed by punching out a center portion of a film made of an insulator such as polyimide and having a thickness of about 80 μm to form an annular shape. As a result, also in this case, the buffer layer interposed between the electrode and the insulator layer includes a conductive adhesive and a conductor in the center portion thereof, and has a non-conductive portion in the periphery thereof. The members are arranged.

In the case of such a plasma processing apparatus, when the insulator layers 12 to 15 are adhered to the surface of the cathode portion 10 on which the object to be processed is mounted, that is, the upper surface thereof, a dedicated buffer layer for keeping the thickness of the buffer layer constant. Even if there is no jig or the like, the thickness of the buffer layer is uniquely determined based on the thickness of the insulator film 114 simply by simply pressing down. Thus, a plasma processing apparatus in which abnormal discharge is less likely to occur in the electrode can be easily manufactured.

[0034]

As is clear from the above description, in the plasma processing apparatus according to the first solution of the present invention, the buffer layer also functions as an extension of the electrode. The substantial capacity between the object and the object increases,
As a result, there is an advantageous effect that a plasma processing apparatus in which abnormal discharge hardly occurs in the electrodes can be realized.

Further, in the plasma processing apparatus according to the second solution of the present invention, since the potential distribution is made uniform even at the conductive adhesive, the plasma processing apparatus in which abnormal discharge is unlikely to occur in the electrodes is provided. There is an advantageous effect that the device can be easily realized.

Further, in the plasma processing apparatus according to the third solution of the present invention, since only the central portion of the buffer layer functions as an extension of the electrode, abnormal discharge is more likely to occur in the electrode. There is an advantageous effect that a difficult plasma processing apparatus can be realized.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional structural view of an electrode in a first embodiment of a plasma processing apparatus of the present invention.

FIG. 2 is a longitudinal sectional view of an electrode according to a second embodiment of the present invention.

FIG. 3 is a longitudinal sectional structural view of an electrode according to a third embodiment of the present invention.

FIG. 4 is a schematic diagram illustrating an overall structure of a plasma processing apparatus.

FIG. 5 is a longitudinal sectional structural view of a conventional electrode.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Wafer (substrate, to-be-processed object) 2 Plasma 3 Anode part (one of a parallel plate, upper electrode, counter electrode) 4 Vacuum chamber main body 5 Vacuum chamber lid part 6 Variable valve (pressure control mechanism, exhaust means) 7 Vacuum pump (Vacuum pressure generation source, exhaust means) 8 Blocking capacitor 9 RF power supply (high frequency application circuit) 10 Cathode unit (the other of parallel plates, lower electrode, workpiece mounting electrode, electrode) 11 Adhesive (insulating adhesive, Non-conductive adhesive layer, buffer adhesive layer, buffer layer) 12 Insulator film (insulator thin plate, sealing insulating layer, conductor embedded insulator layer, insulator layer) 13 Adhesive (insulating, non-conductive adhesive layer) , Sealing adhesive layer,
Conductor embedded insulator layer 14 Metal film (embedded conductor foil, conductive embedded layer, first conductor,
Conductor embedded insulator layer) 15 Insulator film (insulator thin plate, sealing insulating layer, conductor embedded insulator layer, insulator layer) 110 Adhesive (conductive adhesive layer, buffer adhesive layer, buffer layer) 111 metal Film (good conductor foil, conductive buried layer, second conductor,
Conductor) 112 Escape groove (adhesive overflow space, partition groove) 113 Adhesive (annular insulating adhesive, non-conductive adhesive member, edge of buffer layer) 114 Insulator film (annular insulator plate, non-conductive interface) Insertion member,
Edge of buffer layer)

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kazuki Shigeyama 1-5-5 Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture Inside Kobe Research Institute, Kobe Steel Ltd. (72) Inventor Toshihisa Nozawa, Nishi-ku, Kobe City, Hyogo Prefecture 1-5-5 Takatsukadai Kobe Steel, Ltd. Kobe Research Institute

Claims (3)

[Claims] 1. A plasma processing apparatus comprising: an electrode for mounting a workpiece facing a plasma space; and an insulator layer provided with a buffer layer interposed between the electrode and the electrode. A plasma processing apparatus comprising an adhesive. 2. The plasma processing apparatus according to claim 1, wherein a conductor is buried at the buffer layer. 3. The buffer layer according to claim 1, wherein a non-conductive member is disposed at an edge of the buffer layer.
The plasma processing apparatus described in the above.