JPH0850997A - Electrode for high-frequency discharge and high-frequency plasma substrate treatment device - Google Patents

Abstract

PURPOSE:To eliminate a problem in nonuniformity of plasma density to utilize in substrate treatment in high-frequency discharge for forming high-density plasma with hollow discharge generated. CONSTITUTION:Grooves 35 consisting of a plurality of peripheral grooves 35-1 to 35-17 are concentrically formed on the surface of an electrode for rf hollow discharge. The opening size of the grooves 35 is fixed to the size to generate the hollow discharge. In the depth of the grooves 35, the grooves 35 are shallow in depth at the position corresponding to the portion liable to have high plasma density in plasma space, and are deep in depth at the position corresponding to the portion liable to have low plasma density by appropriately engaging and inserting an auxiliary electrode member 36 with and in the said grooves 35. As the result, the grooves 35 have a depth profile enabling to uniform the distribution of the plasma density in the discharge space.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention utilizes a high frequency discharge electrode used for high frequency discharge for surface treatment of various substrates such as semiconductor wafers and glass substrates for liquid crystal displays, and the electrode. The present invention relates to a high frequency plasma substrate processing apparatus.

[0002]

2. Description of the Related Art Conventionally, a substrate such as a semiconductor wafer or a liquid crystal substrate has been utilized by utilizing plasma generated by a capacitively coupled high frequency discharge (hereinafter simply referred to as rf discharge) in which a high frequency circuit is coupled by a capacity of a discharge space. Various processes are performed on the. For example, various thin films such as a semiconductor film and an insulating film are manufactured by a CVD (vapor phase chemical growth) method using plasma generated by rf discharge, and RIE (reactive ion etching) also causes rf discharge. Utilization of the plasma generated by has been actively performed.
Although the definition of rf, that is, "high frequency" is slightly different depending on the field, in the present invention, a frequency of several hundreds Hz or higher will be referred to as "high frequency". Therefore, in some cases, the electric power may be discharged with a frequency not strictly called radio frequency (rf).

The rf discharge method has a simpler structure for discharge, as compared with the method of increasing plasma density by utilizing electron cyclotron resonance or increasing electric energy input efficiency by using helicon waves. However, the plasma density of the formed plasma is relatively low, and thus it is generally unsuitable for a process requiring a high density plasma. As a method of solving such a defect, an attempt is made to increase the plasma density by applying a well-known hollow cathode structure in DC discharge and also in rf discharge by a mechanism similar to the hollow cathode discharge. It is proposed in Japanese Patent Publication No. 3-38345. In the following description, such an rf discharge that employs a mechanism similar to the hollow cathode discharge is referred to as "rf hollow discharge".

10 to 12 are schematic views for explaining the conventional high-frequency discharge electrode disclosed in the above publication, and FIG. 10 is a diagram of the entire high-frequency discharge device adopting the conventional high-frequency discharge electrode, 11 and 12 are diagrams showing examples of conventional electrodes that achieve rf hollow discharge. First, FIG.
The high frequency discharge device shown in FIG. 1 includes a discharge chamber 1, an exhaust system 11 for exhausting the inside of the discharge chamber 1, a gas introduction system 12 for introducing a predetermined gas into the discharge chamber 1, and a pair arranged inside the discharge chamber 1. The electrodes 2 and 3 and a high frequency power source 4 for applying a high frequency to one of the pair of electrodes 2 and 3 are provided. The discharge device shown in FIG. 10 is specifically a device that uses high-frequency discharge for substrate processing such as etching, and the substrate 10 to be processed faces the other electrode 2 of the pair of electrodes 2 and 3. It is placed on the surface and high frequency power is applied to the other electrode 2. In the following description, the electrode on the side where the substrate is placed is called the "substrate electrode", and the other electrode facing the substrate electrode is called the "counter electrode". Further, the facing front surfaces of the pair of electrodes are referred to as “opposing surfaces” in the present application.

Hollow cathode discharge uses a hollow or hollow cathode and utilizes the phenomenon that plasma is drawn into the hollow portion. In this case, the electrons are electrostatically trapped in the hollow portion by the potential barrier around the cathode (negative potential of the cathode) and cumulatively ionize and multiply. As a result, high density plasma is obtained in this portion. In rf discharge, there is no “cathode” in the sense as in DC discharge. However, even in rf discharge,
The device shown in FIG. 10 forms a groove or a recess on the surface of an electrode to cause an electron trapping phenomenon similar to a hollow cathode discharge, and uses this to form high density plasma.

Such a hollow cathode discharge structure is incorporated in the counter electrode 3, and FIGS. 11 and 12 schematically show the state of the facing surface of the counter electrode 3. That is,
As shown in FIG. 11, a large number of small circular recesses 31 are provided on the facing surface of the counter electrode 3, or as shown in FIG.
By providing a plurality of circumferential grooves 32 concentrically, rf hollow discharge is attempted to be achieved in the recess 31 and the groove 32. That is, plasma is drawn into the recesses 31 and grooves 32 and enters, and electrons are electrostatically trapped in the recesses 31 and grooves 32 and cumulatively increase. As a result, high-density plasma is formed. It will be.

[0007]

As described above, research has been conducted to improve the plasma density even in rf discharge by positively utilizing the rf hollow discharge. However, as a remaining problem, the rf discharge plasma still has a problem of non-uniformity of plasma density, and improvement is needed. That is, in the high-frequency discharge device shown in FIG. 10, for example, when the electrode having the structure shown in FIG. 11 is adopted, there is a problem that the amount of plasma captured in each recess 31 cannot be made uniform among the recesses 31. That is, FIG. 13 is a schematic cross-sectional view showing a state where plasma is drawn into and enters the recess 31 of the counter electrode 3 of FIG. 11, but as shown in this figure, plasma enters a certain recess 31 and captures electrons. Although the mechanism for increasing the plasma density due to the above-mentioned is working, the plasma may not be drawn into another adjacent recess 31. On the other hand, when the electrode having the structure shown in FIG. 12 is adopted, the above-mentioned problem is unlikely to occur because the concave portions are circumferentially connected, but the counter electrode 3
There is a problem that the problem of inhomogeneity of the plasma density in the radial direction is not solved.

The invention of the present application has been made in order to solve such a problem, and in rf discharge for forming high density plasma while causing rf hollow discharge,
The first purpose is to solve the problem of nonuniform plasma density. Then, the substrate processing is performed using the high-density plasma in which the problem of such non-uniformity is solved,
The second purpose is to enable highly efficient and highly uniform substrate processing.

[0009]

In order to achieve the first object, the invention according to claim 1 of the present application is arranged so as to face another electrode so as to sandwich a discharge space in which a discharge gas exists. A high-frequency discharge electrode for applying a high-frequency power to one or both of the high-frequency discharge electrode and the other electrode to generate high-frequency discharge to form plasma. A plurality of grooves are formed on the facing surface facing the other electrode of, and the size of the openings of the plurality of grooves is set to a size that causes hollow discharge, and the depth of these grooves is The groove at the position corresponding to the portion where the plasma density is likely to increase in the facing surface direction of the discharge space between the pair of electrodes is shallow and the groove at the position corresponding to the portion where the plasma density is likely to become low in the direction. Kuna' and, with this result, configuration of making uniform the distribution of the plasma density in the discharge space in the direction is in the groove of depth distribution possible. Similarly, in order to achieve the above-mentioned first object, the invention according to claim 2 of the present application is such that, in the configuration of claim 1, the plurality of grooves are arranged concentrically around the center of the facing surface. It has a structure of a circumferential groove. Similarly, in order to achieve the first object, according to the invention of claim 3 of the present application, in the structure of claim 2, a rectangular substrate to be processed is arranged on the opposite surface side of the other electrode. hand,
A high-frequency discharge electrode used when treating the substrate with the plasma, the plurality of grooves is a predetermined angular peripheral shape corresponding to the rectangular shape of the substrate the substrate is a square, The plurality of grooves have a configuration of a predetermined angular shape corresponding to the shape of the substrate. Similarly, in order to achieve the first object, the invention according to claim 4 of the present application is the structure of claim 1, 2 or 3, wherein the depth of the plurality of grooves is the size of the opening in the groove. The auxiliary electrode member having a shape suitable for the height is adjusted by being fitted in the groove. In order to achieve the second object, the invention according to claim 5 of the present application is a processing chamber provided with an exhaust system and a gas introduction system, and a pair of electrodes arranged inside the processing chamber so as to face each other. A high-frequency plasma substrate processing apparatus for processing a substrate by applying high-frequency power to one or both of the pair of electrodes,
One of the pair of electrodes is an electrode.
The electrode for high frequency discharge described in 2, 3, or 4, and the other electrode is a substrate electrode on which the substrate is arranged on the facing surface side.

[0010]

According to the first aspect of the present invention having the above-mentioned structure, the rf hollow discharge is formed at the plurality of grooves, whereby a high density plasma is obtained. At this time, since the groove located in the portion where the plasma density is likely to be high has a shallow depth, the function of increasing the plasma density by electron trapping in the groove becomes weak. Also,
Since the groove located in the portion where the plasma density tends to be low has a large depth, the function of increasing the plasma density in the groove becomes strong. As a result, the plasma density in the facing surface direction of the discharge space between the pair of electrodes is made uniform. Further, in the invention of claim 2, in addition to the operation of claim 1, the plasma that has entered from a specific point of the circumferential groove diffuses in the groove in the circumferential direction to fill the groove. As a result, the plasma density in the groove in the circumferential direction becomes uniform. Further, in the invention of claim 3, in addition to the effect of claim 2, the plasma drawn into the groove diffuses in a square shape along the circumferential shape of the groove. In addition, in the invention of claim 4, in addition to the operation of claim 1, 2 or 3, the depth of the groove is determined according to the thickness and number of the auxiliary electrode members to be inserted and arranged, so as to make the plasma density uniform. The optimum thickness and number are appropriately selected. further,
In the invention of claim 5, the substrate processing is performed by utilizing the action of claim 1, 2, 3 or 4.

[0011]

EXAMPLES Examples of the present invention will be described below. FIG.
FIG. 1 is a schematic diagram illustrating a high-frequency discharge electrode of an embodiment of the present invention and a high-frequency plasma substrate processing apparatus of an embodiment adopting the high-frequency discharge electrode. The device shown in FIG.
In the processing chamber 1 provided with the exhaust system 11 and the gas introduction system 12, the substrate electrode 2 arranged inside the processing chamber 1 so as to face each other, the counter electrode 3 as the high frequency discharge electrode of this embodiment, and the counter electrode 3. It is mainly composed of a high frequency power source 4 and the like for applying high frequency power.

First, the processing chamber 1 is an airtight vacuum container except for the connection points of the exhaust system 11 and the gas introduction system 12 and the entrance / exit for loading / unloading the substrate 10. The attached exhaust system 11 exhausts the inside of the processing chamber 1 to a pressure required for the processing, and the gas introduction system 12 is configured to introduce the gas required for the processing into the processing chamber 1.

The substrate electrode 2 also serves as a substrate holder for holding the substrate 10 at a predetermined position in the processing chamber 1. Further, in the case where a member such as a protective film for preventing damage by plasma or a dielectric film for electrostatically adsorbing the substrate 10 by interaction of plasma and high frequency is provided on the surface of the substrate electrode 2. There is. The substrate may be in direct contact with the facing surface of the electrode, or some specific member may be interposed between the facing surface and the substrate. The substrate electrode 2 is grounded and has a ground potential in this embodiment.

The counter electrode 3 is arranged so as to face the substrate electrode 2. The counter electrode 3 is attached to the base 33 and the rf mounted on the facing surface side of the base 33.
It is composed of a hollow discharge electrode 34. The rf hollow discharge electrode 34 is a member that achieves rf hollow discharge, and has a plurality of grooves, which will be described later, formed on its surface. The base 33 is made of a conductor such as stainless steel. The rf hollow discharge electrode 34 is attached to the base 33 by a method such as screwing or fixing with an adhesive.

As the high frequency power source 4, 13.56 MHz
The one that oscillates high frequency is used. That is, in this embodiment, a high frequency band of several MHz to several hundred MHz is adopted. In this embodiment, the electric power is applied only to the counter electrode 3, but it may be applied to the substrate electrode 2 side, or may be applied to both of them.

Next, the dimensions and shapes of the plurality of grooves will be described in detail with reference to FIGS. 2 and 3. 2 is a schematic plan view illustrating a plurality of grooves formed in the electrode 34 for rf hollow discharge in FIG. 1, and FIG. 3 is a schematic cross-sectional view of the electrode 34 for rf hollow discharge in FIG. As shown in FIGS. 2 and 3, the rf hollow discharge electrode 34 is a substantially disk-shaped member as a whole, and its diameter R is about 200 mm. The plurality of grooves 35 are, specifically, circumferential grooves arranged concentrically around the center of the rf hollow discharge electrode 34 as shown in FIG.

In this embodiment, the width W of the plurality of grooves 35 is W.
1 is about 5 to 10 mm and all have the same width. The thickness W2 of the wall that partitions each groove 35 is also the same.
It is about mm. Further, the depth D of each groove 35 is about 15 to 30 mm, which is about three times the groove width, in a state where an auxiliary electrode member described later is not provided, and all have the same depth. The rf hollow discharge electrode 34 having such a size and shape is formed of aluminum alloy, stainless steel, nickel alloy, or the like. As a forming method, a method such as shaving is adopted.

Now, such an rf hollow discharge electrode 3
The auxiliary electrode members 36 shown in FIGS. 5 to 7 are appropriately fitted into the plurality of grooves 35 of No. 4 to achieve uniform plasma density. The auxiliary electrode member 36 is the electrode 3 for rf hollow discharge.
It is an annular member that can be fitted into the groove 35 of No. 4, and the thickness thereof is, for example, about 1 to 2 mm. Such an auxiliary electrode member 36 is appropriately inserted and arranged in a specific groove 35 according to the distribution of the plasma density in the discharge space between the counter electrode 3 and the substrate electrode 2 shown in FIG. Is adjusted. That is, the thickness of the auxiliary electrode member 36 and the number of the auxiliary electrode members 36 to be fitted in a superposed manner are appropriately selected. As a result, the groove 35 located in the portion of the discharge space where the plasma density is likely to be high is shallow and the groove 35 located in the portion where the plasma density is likely to be low is deep.
The material of the auxiliary electrode member 36 is usually the same as the material of the counter electrode 3. Although the arrangement structure may be simply fitted, when the counter electrode 3 is arranged on the upper side of FIG. 1 and the groove 35 faces the opening downward, a method such as welding, bonding or screwing is used. It may be fixed.

Next, the operation of the high-frequency discharge electrode of the present embodiment will be described while explaining the operation of the plasma substrate processing apparatus having the above structure. First, the substrate 10 carried by the substrate carrying mechanism or the like is carried in from a doorway (not shown) and placed on the facing surface of the substrate electrode 2. Then, it is fixed on the substrate electrode 2 by means of electrostatic attraction or mechanical holding. Next, the exhaust system 11 operates to exhaust the inside of the processing chamber 1 to a predetermined pressure, and the gas introduction system 12 introduces the gas required for processing into the processing chamber 1. A vacuum gauge (not shown) is provided in the processing chamber 1, and the pressure in the processing chamber 1 is controlled to a predetermined value by controlling the exhaust system 11 and the gas introduction system 12 while monitoring the pressure in the processing chamber 1. Maintained at.

In this state, the high frequency power source 4 operates and a high frequency voltage of, for example, 13.56 MHz is applied to the counter electrode 3. As a result, a high frequency electric field is generated in the discharge space between the counter electrode 3 and the substrate electrode 2, and the introduced gas is ionized by this electric field to form plasma in the space. At this time, the rf hollow discharge electrode 34 provided on the counter electrode 3
By the action of, the plasma density in the discharge space is made uniform in the facing surface direction, that is, the substrate processing surface direction. Then, a desired treatment is applied to the substrate treatment surface according to the type of introduced gas and the like.

A specific process will be described. For example, when the apparatus employing the high-frequency discharge electrode of this embodiment is used as a CVD apparatus to perform a process of depositing an amorphous silicon film on a substrate, a raw material is introduced from a gas introduction system. Monosilane as a gas and hydrogen as a carrier gas are introduced, and the plasma is operated as described above to react the raw material gas to deposit an amorphous silicon film on the substrate. As described above, since the formed plasma has a uniform density distribution in the direction of the substrate processing surface, the film thickness and film quality of the deposited film are uniform, so that a good quality film should be manufactured. You can

Next, the reason why the distribution of the plasma density in the discharge space can be adjusted by adjusting the depth of the groove will be supplementarily described. In the rf hollow discharge, the plasma density is increased by electrostatically trapping electrons, but the high-frequency discharge electrode of this embodiment adjusts the plasma density by adjusting the amount of electrons trapped in each groove. It is carried out.

FIG. 4 is a diagram showing the spatial potential distribution inside a groove and in the vicinity of the outlet of the groove, where x is the width direction of the groove,
y represents the depth direction of the groove, and z represents the magnitude of the space potential. In the rf hollow discharge, plasma is drawn into the groove formed on the electrode surface to form high density plasma. The degree to which the plasma density increases depends on the depth of the groove. When the plasma diffuses in the y direction in FIG. 4 and enters the inside of the groove, the plasma potential enters the center of the groove due to the "property of making the plasma have an equal potential everywhere". That is, the space potential at the center of the groove becomes the plasma potential due to the plasma entering the groove. Since the plasma potential is always kept higher than the potential of the groove wall, the space potential distribution eventually becomes high as shown in the figure, with the central portion of the groove being high and being abruptly lowered as it approaches the groove walls on both sides. This distribution has an upwardly convex potential distribution when viewed in the x direction. An upwardly convex potential distribution for an electron corresponds to a concave potential distribution. That is, the electrons placed at the position indicated by e- in FIG. 4 fall along the direction of the arrow in the figure (upward). The electrons that have reached the potential valley (potential peak in the figure) climb up the potential slope on the opposite side and fall again. The reciprocating motion like this swing is the essence of electron trapping.

Increasing the depth of the groove means providing a wider place (depth of the edge in the y direction) necessary for this reciprocating motion, that is, the deeper the groove, the more electrons. Will reciprocate. The reciprocating motion of many electrons increases the chances that they will collide with neutral particles, thus promoting ionization and increasing plasma density. That is, the amount of trapped electrons is adjusted by adjusting the depth of the groove, and as a result, the ionization action inside the groove is adjusted and the plasma density of the plasma formed near the exit of the groove is adjusted. Of.

Therefore, the depth of the groove 35 located at the portion where the plasma density is likely to be high is made shallow, and the depth of the groove 35 located at the portion where the plasma density is likely to be low is made deep as a result. The plasma density in the discharge space is made uniform. Which part of the discharge space is likely to have a high density and which part is likely to have a low density varies depending on the shape of each electrode, the mode of the applied high-frequency power, and the like, and therefore cannot be generally determined. However, in the device having the configuration shown in FIG. 1, the electric field may become strong near the end of the counter electrode 3, and in this case, the density tends to be high near the electrode end in the discharge space.

Next, an experimental example in which the auxiliary electrode member 36 is appropriately arranged to adjust the plasma density distribution will be described. 5 to 7 show an experiment in which an rf hollow discharge electrode similar to the rf hollow discharge electrode 34 shown in the above-described embodiment (groove width and groove depth are different) was used to perform rf hollow discharge. It is a figure which shows a result. The experimental conditions in these figures are as shown in Table 1 below. Argon is used as the discharge gas.

[Table 1]

5 to 7, the horizontal axis represents the distance from the center of the counter electrode and the vertical axis represents the ion current. A double probe type electrostatic probe was used as a measuring element for measuring the ion current. In such an electrostatic probe, it is known that when a bias potential of a certain level or more is applied to the probe, the inflowing ion current value is saturated, and the saturation current value is proportional to the plasma density. Therefore, the potential of the electrostatic probe was set to a value in a region where the ionic current was saturated, and measurement was performed while moving the tip of the probe in this state. Therefore, the vertical axis in FIGS. 5 to 7 is the ion saturation current. The arrangement of the auxiliary electrode member 36 used in the experimental example of each drawing (that is, the depth distribution of the groove of the rf hollow discharge electrode) is shown in the lower column of each drawing.

First, the experimental example of FIG. 5 will be described. When A10, A20, and A30 in FIG. 5 are adjusted by using the auxiliary electrode member 36, the groove depth distribution as shown in the lower column of FIG. B10, B20, and B30 are ion currents when measured with the groove having the same depth without using the auxiliary electrode member 36. And of these, A1
0 and B10 are A2 when the distance from the opposing surface of the opposing electrode (the upper surface of the groove wall of the rf hollow discharge electrode) is 10 mm.
0, B20 is 20mm, A30, B30 is 30m
The measurement result in the case of m is shown. As shown in FIG. 5, it is understood that the plasma density in the discharge space is made uniform at any distance in the experiment using the auxiliary electrode member 36 as compared with the case where it is not used. In particular, it was found that a uniformity of ± 1.7% was achieved when the distance from the facing surface was 30 mm. The depth distribution of the groove after adjustment shown in FIG. 5 will be described. If the grooves are 35-1, 35-2, 35-3, ...
5-1 to groove 35-8 has a depth of 15 mm, groove 35-
9 to groove 35-13 has a depth of 13 mm, groove 35-14
Has a depth of 12 mm, the groove 35-15 has a depth of 13 mm, the groove 35-16 has a depth of 0 mm (no groove), and the groove 35-17 has a depth of 15 mm.

In the experimental example shown in FIG. 6, C10, C
20, C25, C30, when using the auxiliary electrode member 36, the distance from the facing surface is 10 mm, 20 mm, 25
The measurement results at the positions of mm and 30 mm are shown as D10, D
Reference numeral 30 indicates the measurement results when the distance from the facing surface is 10 mm and 30 mm when the auxiliary electrode member 36 is not used. Also in FIG. 6, the auxiliary electrode member 36
When used, the uniformity is much higher than when not used, especially when the distance from the facing surface is 30 m.
It was found that the uniformity was ± 1.8% at the position m. Similarly, the depth distribution of the groove after adjustment in this case will be described. The groove depth from the groove 35-1 to the groove 35-6 is 20.
mm depth, groove 35-7 has a depth of 18 mm, groove 35-8 to groove 35-10 has a depth of 17 mm, groove 35-11 has a depth of 0 mm (no groove), groove 35-12 has 20 mm. Was the distribution of.

Further, in the experimental example shown in FIG. 7, E10,
E30 shows the measurement results at the positions where the distance from the facing surface is 10 mm and 30 mm when the auxiliary electrode member 36 is used, and the distance from the facing surface when F10 and F30 do not use the auxiliary electrode member 36. Indicates the measurement results at the positions of 10 mm and 30 mm, respectively. In FIG. 7 as well, when the auxiliary electrode member 36 is used, much higher uniformity is obtained as compared with the case where it is not used, and in particular, it is ± 2.9% when the distance from the facing surface is 30 mm. It was found to be uniform. Similarly, the depth distribution of the groove after adjustment in this case will be described. The depth from the groove 35-1 to the groove 35-6 is 18 mm, the depth of the groove 35-7 is 7 mm, and the depth of the groove 35-8 is 0 mm. Depth (without groove), groove 35
-12 had a depth distribution of 30 mm.

As is apparent from the above experimental example, the auxiliary electrode member 36 is used to adjust the depth distribution of the groove, and the depth of the groove 35 at the position corresponding to the portion where the plasma density tends to be high is made shallow. Groove 3 at a position corresponding to a portion that tends to be lowered
By making the depth of 5 deeper, the non-uniformity of the plasma density can be improved very well and a highly uniform plasma can be obtained. Incidentally, in the rf hollow discharge, it is generally required that the product dp of the opening size d of the hollow and the atmospheric pressure p is within a certain range. Accordingly, rf hollow discharge electrodes having different groove widths are appropriately used. The range to which dp should be is not determined unconditionally because it depends on the specific shape of the electrode, the type of gas, and the material of the electrode, and is often determined experimentally.

Next, another embodiment of the high frequency plasma substrate processing apparatus of the present application will be described. FIG. 8 is a schematic plan view illustrating the structure of a high frequency discharge electrode according to another embodiment of the present invention. The electrode of this embodiment is used in an apparatus for processing a rectangular substrate such as a liquid crystal substrate when manufacturing a liquid crystal display. In this case, the opposing surface of the substrate electrode on which the rectangular substrate is arranged is formed in a predetermined angular shape that matches the shape of the substrate, but as an example of the high-frequency discharge electrode facing the substrate electrode, The facing surface of the counter electrode 3 is also formed in a circumferential shape that matches the shape of the substrate. That is, it is configured so that the discharge space between the substrate electrode and the counter electrode 3 has a rectangular cross section and a plasma region having a rectangular cross section is formed. With such a structure, it is possible to perform uniform treatment on the surface of the rectangular substrate.

The plurality of grooves 35 formed in the counter electrode 3 of this embodiment are also circumferentially arranged concentrically around the center of the facing surface as in the above embodiment.
Unlike the above-described embodiment, as shown in FIG. 8, it has a rectangular shape substantially similar to the rectangular shape of the substrate. When the configuration of the present invention is applied to the rectangular counter electrode 3 used for processing such a rectangular substrate, more advantageous effects can be obtained as compared with the case of the circular counter electrode as in the above embodiment. That is, FIG.
It is relatively easy to form a plasma region having a circular cross section by using a circular counter electrode as shown in FIG. However, it is generally difficult to form a plasma region having a rectangular cross section by using the rectangular counter electrode 3 as shown in FIG.
That is, even if the electrodes are formed in a square shape, the plasma does not have a uniform square shape distribution, and the plasma density becomes extremely low at the corners or conversely the discharge concentrates and becomes extremely high. .

However, as in the present embodiment, a plurality of grooves 35 for causing the electrode discharge for rf hollow discharge are formed in FIG.
If a rectangular shape is formed in accordance with the shape of the counter electrode 3 as shown in FIG.
Since it diffuses in a circular shape in the inside, the plasma in the discharge space is uniformly formed in a square shape by being attracted by the plasma in the groove 35. That is, by forcibly diffusing the plasma along the circumferential groove 35, the shape of the plasma region can be shaped in a so-called rectangular shape. Then, by adjusting the amount of plasma drawn into the groove 35 of each circumference by adjusting the depth distribution of the groove as described above, it is possible to form a uniform plasma in the discharge space having a rectangular cross section. .
The "square" is of course a concept including both squares and rectangles.

Next, another example of the plurality of grooves of the present invention will be briefly described. FIG. 9 is a schematic plan view illustrating another example of the plurality of grooves of the present invention. As shown in FIG. 9, there can be many variations in the configuration of the plurality of grooves 35. That is, for example, FIGS. 9 (a) and 9 (b)
A plurality of grooves 35 having a circumferential shape (a) or a circumferential shape (b) which are concentric as shown in FIG. 9 but are not a complete circumference of 360 degrees, or non-concentric as shown in FIG. 9C. Multiple grooves 3 arranged
No. 5 can be adopted in the present invention. So at least
It suffices if the grooves 35 are separately provided at the position corresponding to the portion where the plasma density is likely to increase and the position corresponding to the portion where the plasma density is likely to be low in the discharge space.

In the above description, the auxiliary electrode member 36 is used.
Although the example in which the depths of the plurality of grooves 35 are adjusted by using is described, the auxiliary electrode member 36 is not used, and the grooves 35 having different depths are directly formed by shaping the rf hollow discharge electrode itself. Of course, it is okay to do so.

[0037]

As described above, according to the invention described in claim 1 of the present application, the depth distribution of the groove that causes the hollow discharge is configured to be a predetermined distribution, so that the plasma density in the discharge space is uniform. Be converted. Further, according to the invention of claim 2, in addition to the effect of claim 1, since the plasma diffuses along the circumferential groove, the non-uniformity of the plasma in the circumferential direction is further resolved. In this case, plasma can be obtained with good uniformity. According to the invention of claim 3, in addition to the effect of claim 2, since the plasma can be forcibly diffused along the circumferential groove, it is difficult to obtain a uniform plasma. Also in the processing on the substrate, it is possible to obtain uniform plasma and perform uniform processing. Further, according to the invention of claim 4, in addition to the effect of claim 1, 2 or 3, the depth distribution of the groove is adjusted by the placement of the auxiliary electrode member in the groove, so that the adjustment work is extremely difficult. The effect that it becomes easy is obtained. Further, according to the invention of claim 5, the above-mentioned claims 1, 2,
Since the substrate processing is performed by utilizing the effect 3 or 4, the effect that the substrate processing with high efficiency and high uniformity can be obtained is obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating a high frequency discharge electrode according to an embodiment of the present invention and a high frequency plasma substrate processing apparatus according to an embodiment employing the high frequency discharge electrode.

2 is a schematic plan view illustrating a plurality of grooves formed in an rf hollow discharge electrode in FIG.

FIG. 3 is a schematic cross-sectional view of the rf hollow discharge electrode of FIG.

FIG. 4 is a diagram showing the spatial potential distribution inside a groove and in the vicinity of the outlet of the groove, where x is the width direction of the groove, y is the depth direction of the groove, and z is the magnitude of the space potential.

FIG. 5 is a diagram showing an experimental result of high-frequency plasma discharge using an rf hollow discharge electrode similar to the rf hollow discharge electrode shown in the example.

FIG. 6 is a diagram showing another experimental result under different conditions from FIG.

FIG. 7 is a diagram showing another experimental result under different conditions from FIGS. 5 and 6;

FIG. 8 is a schematic plan view illustrating a configuration of a counter electrode in another example.

FIG. 9 is a schematic plan view illustrating another example of the plurality of grooves of the present invention.

FIG. 10 is a schematic diagram illustrating a conventional high-frequency discharge electrode, and is a diagram of an entire high-frequency discharge device in which the conventional high-frequency discharge electrode is adopted.

FIG. 11 is a diagram showing an example of an electrode structure for achieving electrode discharge for rf hollow discharge in FIG.

FIG. 12 is a diagram showing an example of another electrode structure for achieving electrode discharge for rf hollow discharge in FIG.

FIG. 13 is a schematic cross-sectional view showing a state where plasma is drawn into and enters the concave portion of the counter electrode of FIG.

[Explanation of symbols]

 1 Processing Chamber 11 Exhaust System 12 Gas Introduction System 2 Substrate Electrode 3 Counter Electrode 34 rf Hollow Discharge Electrode 35 Groove 4 High Frequency Power Supply

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Daisuke Aonuma 5-8-1, Yotsuya, Fuchu-shi, Tokyo Nichiden Anneruba Co., Ltd. (72) Inventor Ka Watanabe 5-8-1, Yotsuya, Fuchu-shi, Tokyo Inside Anelva Co., Ltd.

Claims (5)

[Claims] 1. A high-frequency discharge electrode arranged to face another electrode so as to sandwich a discharge space in which a discharge gas is present, wherein the high-frequency discharge electrode and / or the other electrode have a high-frequency wave. In an electrode for high-frequency discharge that applies electric power to generate high-frequency discharge to form plasma, a plurality of grooves are formed on a surface of the high-frequency discharge electrode facing the other electrode. The size of the opening is set to a size that causes a hollow discharge, and the depth of the grooves is a position corresponding to a portion where the plasma density is likely to increase in the direction of the facing surface of the discharge space between the pair of electrodes. The groove is shallow, and the groove at the position corresponding to the portion where the plasma density is likely to be low in the relevant direction is deep. High-frequency discharge electrode, wherein a be Ichika has in the groove of depth distribution possible. 2. The high-frequency discharge electrode according to claim 1, wherein the plurality of grooves are circumferential grooves arranged concentrically around the center of the facing surface. 3. The electrode for high-frequency discharge according to claim 2, wherein a rectangular substrate to be treated is arranged on the opposite surface side of the other electrode and is used when treating the substrate with the plasma. The high frequency discharge electrode, wherein the plurality of grooves have a predetermined angular shape corresponding to the rectangular shape of the substrate. 4. The depth of the plurality of grooves is adjusted by inserting and arranging an auxiliary electrode member having a shape matching the size of the opening in the groove. The electrode for high frequency discharge according to 1, 2, or 3. 5. A processing chamber having an exhaust system and a gas introduction system, and a pair of electrodes arranged inside the processing chamber so as to face each other, and high-frequency power is supplied to one or both of the pair of electrodes. A high frequency plasma substrate processing apparatus for applying a voltage to process a substrate, wherein one of the pair of electrodes is an electrode.
2. The high-frequency plasma substrate processing apparatus, wherein the high-frequency discharge electrode is described in 2, 3, or 4, and the other electrode is a substrate electrode on which a substrate is arranged on the opposite surface side.