KR20100109492A - Plasma processing apparatus - Google Patents

Abstract

PURPOSE: A plasma processing device is provided to improve the uniformity of plasma in the diameter direction of a wafer by distributing power which is supplied to each winding coil. CONSTITUTION: A plasma processing to an object is executed in a processing container(100). A first high frequency power(140) outputs the power in the high frequency. A high frequency antenna(120) comprises the n number of middle coils which are installed between an external coil and an inner coil. The external coil, the inner coil, and the middle coil are wound into a concentric shape around the center axis of the high frequency antenna in the outside of the processing container. A dielectric window(105) is installed in the opening of the processing container. The dielectric window guides the energy of the electromagnetic field which is generated from the high frequency antenna into the processing container.

Description

PLASMA PROCESSING APPARATUS

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus for performing plasma processing on a target object, and more particularly, to a high frequency antenna.

Examples of an apparatus for exciting a plasma to finely process a target object include a capacitively coupled plasma processing apparatus, an inductively coupled plasma processing apparatus, and a microwave plasma processing apparatus. Among them, an Inductively Coupled Plasma (ICP) processing apparatus arranges a high frequency antenna in a dielectric window provided on a ceiling surface of a processing vessel, flows a high frequency current through a coil of the antenna, and generates an electromagnetic field around the coil. The electric field energy is introduced into the processing vessel through the dielectric window, and the gas is excited by the electric field energy to generate plasma (see Patent Document 1, for example).

In Patent Document 1, the high frequency antenna is formed by two spiral coils on the outer circumferential side and the inner circumferential side in a planar shape. The two spiral coils are power split, thereby adjusting the plasma density distribution of the inductively coupled plasma formed in the process chamber.

Japanese Patent Publication No. 2007-311182

However, in the above-described high frequency antenna, two donut-shaped plasmas are produced from a circular current pattern obtained by two coils on the outer circumferential side and the inner circumferential side, and the plasma density decreases between the two donut-shaped plasmas, As a result, the in-plane uniformity of plasma processing with respect to the to-be-processed object falls. In addition, plasma density, such as pressure, also caused a change in plasma density, making it difficult to ensure plasma uniformity.

In particular, with the recent increase in the size of the object to be processed, the device has also increased in size. Therefore, even in a large plasma processing apparatus, it is necessary to generate plasma uniformly in a wide plasma excitation space, and it becomes a situation that it is more difficult to ensure the uniformity of plasma.

In view of the above problems, an object of the present invention is to provide a plasma processing apparatus capable of improving in-plane uniformity of plasma density to plasma processing characteristics.

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, according to one aspect of this invention, the processing container in which a plasma processing is performed to a to-be-processed object inside, the 1st high frequency power supply which outputs a high frequency, the outer coil from the outside of the said processing container, an inside A high frequency antenna in which a coil and n intermediate coils (n is an integer equal to or greater than 1) provided between the coil and the central axis are concentrically formed, and a part of a wall surface of the processing container, and an electromagnetic field generated from the high frequency antenna. A plasma processing apparatus having a dielectric window for introducing energy into the processing vessel is provided.

According to this configuration, the high frequency antenna has an outer coil wound in a concentric shape with respect to the central axis, an inner coil and n intermediate coils (n is an integer of 1 or more) provided therebetween. As a result, the plasma can be produced by the number n (n ≧ 1) of intermediate coils in addition to the inner coil and the outer coil in the plasma excitation region. Therefore, the stagnation of the plasma density in the intermediate region between the coils generated when the plasma is made of only two coils can be eliminated, and the plasma can be uniform as a whole. Thereby, in-plane uniformity of the process of a to-be-processed object can be maintained.

It may be provided at least between the said outer coil and the said inner coil, and may have the power division part which divides the high frequency power output from the said 1st high frequency power supply into a desired ratio, and supplies it to each coil.

For example, first, the high frequency power of the largest high power is input to the outer coil, and then the lower high frequency power is input to the inner coil, and finally, the remaining high frequency power is input to the middle coil.

On the edge side of the object to be treated, electrons or ions in the plasma diffuse to the wall and disappear, so that the plasma density tends to be lowered. In consideration of this, first, high power is applied to the outer coil so that the outer plasma density is the highest. Thereby, the fall of the etching rate of the edge part of a to-be-processed object, etc. can be prevented. The remaining high frequency power divided by the power divider is divided into an inner coil and an intermediate coil and input.

As a result, it is possible to control the plasma density on the outside of the plasma excitation region to be slightly higher than the overall plasma density, and to prevent the drop in the plasma density at the central portion between the inside and the outside, thereby making the overall plasma uniform. Thereby, in-plane uniformity of the process of a to-be-processed object can be maintained.

The power dividing unit may be provided between the coils and divide the power of the high frequency output from the first high frequency power supply at a desired ratio, respectively, and supply them to each coil.

At least one of the coils may be movable such that the distance to the dielectric window is variable.

When the said power division part is not provided between two coils, either of the said two coils may be movable.

The two or more power dividers may be provided symmetrically with respect to the central axis.

The two or more power dividers may be provided asymmetrically with respect to the central axis, and may be shielded by a shield member.

The outer coil, the inner coil and the intermediate coil are each formed of a plurality of coils, each feed point of the plurality of coils forming the outer coil is provided at a position symmetrical with respect to the central axis, Each feed point of the plurality of coils to be formed may be provided at a position symmetrical with respect to the central axis, and each feed point of the plurality of coils forming the inner coil may be provided at a position symmetrical with respect to the center axis.

The feed point of each said coil may be arrange | positioned at any one of 180 degrees, 120 degrees, 90 degrees, 72 degrees, and 60 degrees with respect to the said central axis.

A blocking capacitor may be interposed in each of the coils.

Two or more power dividers may have a variable capacitor.

The power divider is divided into a measuring device that measures at least one of high current, voltage, and phase supplied to each of the coils, and at least one of high current, voltage, and phase measured by the measuring device. You may have the control apparatus which controls the power ratio which becomes.

The control apparatus may have a memory and control a power ratio divided into the power dividing unit according to a recipe previously stored in the memory.

A second high frequency power source for outputting a high frequency, wherein one of the outer coil, the inner coil and the intermediate coil is connected to the first high frequency power source, and the remaining two coils not connected to the first high frequency power source are You may further have a power division part connected to a 2nd high frequency power supply which divides the high frequency power output from the said 2nd high frequency power supply into a desired ratio, and supplies it to the said remaining two coils.

The first high frequency power supply may be connected to the outer coil, and the second high frequency power supply may be connected to the inner coil and the intermediate coil.

The second and third high frequency power supplies for outputting a high frequency, wherein any one of the outer coil, the inner coil and the intermediate coil is connected to the first high frequency power supply, the remaining two not connected to the first high frequency power supply One of the coils may be connected to the second high frequency power supply, and the other of the remaining two coils may be connected to the third high frequency power supply.

As described above, according to the present invention, in-plane uniformity of plasma density to plasma treatment characteristics can be improved.

1 is a longitudinal sectional view of a plasma processing apparatus according to a first embodiment of the present invention.
2 is a diagram for explaining the configuration of a high frequency antenna according to this embodiment.
FIG. 3A shows the plasma density in the radial direction of the wafer, and FIG. 3B is a diagram for explaining the operation of the blocking capacitor.
4 shows an equivalent circuit according to this embodiment.
5 is a diagram showing a modification of the plasma processing apparatus according to the first embodiment.
6 is a diagram showing another modified example of the plasma processing apparatus according to the first embodiment.
7 is a diagram showing another modified example of the plasma processing apparatus according to the first embodiment.
FIG. 8A is a longitudinal sectional view of the plasma processing apparatus according to the second embodiment of the present invention, and FIG. 8B is a view for explaining the configuration of the high frequency antenna according to this embodiment.
9 is a diagram for explaining a voltage state in the circumferential direction of the wafer.
10 is a longitudinal sectional view of the plasma processing apparatus according to the third embodiment of the present invention.
FIG. 11A is a longitudinal sectional view of the plasma processing apparatus according to the fourth embodiment of the present invention, and FIG. 11B is a diagram for explaining the configuration of the high frequency antenna according to this embodiment.
12 is a longitudinal sectional view of a plasma processing apparatus according to a fifth embodiment of the present invention.
13 is a longitudinal sectional view of the plasma processing apparatus according to the sixth embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, in this specification and drawing, the same code | symbol is attached | subjected about the component which has a substantially same functional structure, and abbreviate | omits duplication description.

<First Embodiment>

(Overall Configuration of Plasma Processing Unit)

First, the overall configuration of the plasma processing apparatus according to the first embodiment of the present invention will be described with reference to FIGS. 1 and 2. 1 is a diagram schematically illustrating a longitudinal section of an inductively coupled plasma processing apparatus. 2 is a diagram for explaining the configuration of a high frequency antenna.

As shown in FIG. 1, the plasma processing apparatus 10, such as an etching apparatus, for example, has the processing container 100 which plasma-processes the wafer W carried in from the gate valve GV. The processing container 100 is formed in a cylindrical shape, for example, made of metal such as aluminum, and grounded. The inner wall of the processing container 100 is anodized. In addition, the inner wall of the processing container 100 may be covered with a dielectric such as quartz or yttria.

The dielectric window 105 is inserted into the opening of the processing container 100 on the ceiling surface of the processing container 100, thereby maintaining the airtightness of the space in the processing container 100. The dielectric window 105 is a circular plate formed of alumina or quartz or the like. The dielectric window 105 transmits energy of the electromagnetic field generated from the high frequency antenna 120 and introduces the energy into the processing container 100.

The shower plate 110 is embedded in the lower surface of the dielectric window 105. The gas introduction pipe 110a is installed in the shower plate 110. The gas introduction pipe 110a discharges gas into the processing container 100 from the plurality of gas holes 110b opened to the wafer W side. The gas introduction pipe 110a penetrates toward the outside from the center of the ceiling surface of the processing container 100 and is connected to the gas supply source 115.

The high frequency (RF) antenna 120 is disposed in the atmospheric side of the dielectric window 105. As shown in FIG. 2, the axis passing through the center of the dielectric window 105 as the central axis O is virtually divided into the outer zone, the inner zone, and the middle zone.

The high frequency antenna 120 has an outer coil 120a disposed in the outer zone, an inner coil 120c disposed in the inner zone, and an intermediate coil 120b disposed in the intermediate zone. The outer coil 120a, the intermediate coil 120b, and the inner coil 120c are provided concentrically with respect to the center axis O. As shown in FIG.

In addition, although each coil 120a-120c is circumferentially circumscribing each zone, it is not limited to this, You may wind up multiple times. In addition, although one intermediate zone is provided in this embodiment, it is not limited to this, The middle coil may be divided | segmented into two or more zones, and the intermediate coil may be provided one to one in each intermediate zone.

Feed rods 125a to 125c are connected to one end of each of the coils 120a to 120c, respectively. The feed rods 125a to 125c are connected to the first high frequency power supply 140 via the matching unit 135. The high frequency power output from the first high frequency power supply 140 passes through the matching unit 135 and each of the feeding rods 125a to 125c and is applied to each of the coils 120a to 120c, whereby the respective coils 120a to 120c. High frequency current flows through

The power splitter 130 is interposed between the coils 120a to 120c. The power divider 130 has variable impedance circuits (for example, variable capacitors) 130a and 130b. The outer antenna circuit is composed of only the outer coil 120a. The intermediate antenna circuit is composed of a variable impedance circuit 130a and an intermediate coil 120b. The inner antenna circuit is composed of a variable impedance circuit 130a, a variable impedance circuit 130b, and an inner coil 120c.

The variable impedance circuits 130a and 130b function as impedance adjusting units. That is, by adjusting the capacitance of the variable impedance circuit 130a, the impedance of the middle and inner antenna circuits can be controlled to control the ratio of the current flowing through the outer and middle antenna circuits as described later. Similarly, by adjusting the capacitance of the variable impedance circuit 130b, the impedances of the intermediate antenna circuit and the inner antenna circuit can be controlled to control the ratio of the current flowing through the intermediate antenna circuit and the inner antenna circuit.

As described above, the variable impedance circuits 130a and 130b have a power division function of dividing the high frequency power output from the first high frequency power supply 140 into a desired ratio and supplying the coils to the respective coils. In addition, although the variable capacitor should just be provided between the outer coil 120a and the inner coil 120c, if it is provided between each coil like the present Example, the precision of power division control will improve.

According to this configuration, high frequency power, for example, 13.56 MHz, is supplied from the first high frequency power supply 140 to the high frequency antenna 120 during the plasma processing, so that high frequency current is applied to each of the coils 120a to 120c of the high frequency antenna 120. Flow. As a result, an electromagnetic field is generated around the coil, and the electric field energy is injected into the processing container 100 through the dielectric window 105. The energy input excites the gas and thus generates a plasma. The density distribution of the plasma at this time is controlled by the impedance control of the outer coil 120a, the intermediate coil 120b, and the inner coil 120c by the variable impedance circuits 130a and 130b, which will be described later.

Blocking capacitors 145a to 145c are interposed in the other ends of the outer coil 120a, the intermediate coil 120b, and the inner coil 120c, respectively, and are grounded. The functions of the blocking capacitors 145a to 145c will also be described later.

Inside the processing container 100, a mounting table 150 on which the wafer W is placed is provided. The wafer W placed on the mounting table 150 is attracted and held by an electrostatic chuck (not shown). The high frequency bias power supply 160 is connected to the mounting table 150 via the matching unit 155. The high frequency bias power supply 160 applies a high frequency power for bias, for example, a high frequency power having a frequency of 2 MHz to the mounting table 150 during plasma processing. By the bias high-frequency power, ions in the plasma generated in the processing container 100 are effectively introduced into the wafer W.

An exhaust device 170 including a vacuum pump is connected to the bottom of the processing container 100 via an exhaust pipe 165, and the inside of the processing container 100 has a desired vacuum degree of, for example, about 1.33 Pa. do.

The power divider 130 is connected to the control device 220. The control apparatus 220 has the CPU 220a, the memory 220b, and the interface (I / F) 220c, and each part is enabled to exchange signals by the internal bus 220d.

In the memory 220b, a recipe for controlling the respective capacitances of the variable impedance circuits 130a and 130b of the power divider 130 is stored in advance. In the recipe, the capacitances of the variable impedance circuits 130a and 130b are determined for each process. The CPU 220a selects a recipe that matches the process, and controls the respective capacities of the variable impedance circuits 130a and 130b according to the recipe. The recipe may be stored in a hard disk or the like, may be stored in a storage medium such as a CDROM, or may be appropriately downloaded through a network.

(Antenna configuration)

For example, if the high frequency antenna is formed by two spiral coils on the outer circumferential side and the inner circumferential side, two donut-shaped plasmas are produced from a circular current pattern obtained by the two coils on the outer circumferential side and the inner circumferential side. The plasma density decreases between these two donut type plasmas. For example, the curve Np of FIG. 3A shows an example of the plasma density distribution obtained by two spiral coils on the outer circumferential side and the inner circumferential side. The plasma density is high at the outer peripheral part and the inner peripheral part of the wafer having a diameter of 300 mm, and the plasma density between them is low. According to this, since the in-plane uniformity of plasma processing with respect to a wafer worsens, a yield will become low and productivity will fall.

In contrast, in the high frequency antenna 120 according to the present embodiment, three coils of the outer coil 120a, the intermediate coil 120b and the inner coil 120c are wound concentrically about the central axis O. Accordingly, as shown by the curve Nc of FIG. 3A, in the plasma density distribution obtained by the three coils of the outer coil 120a, the intermediate coil 120b, and the inner coil 120c, the outer peripheral portion and the inner peripheral portion of the wafer are provided. Since the plasma density is high and the intermediate coil 120b is present, the plasma density therebetween does not decrease. According to this, since the in-plane uniformity of the plasma processing with respect to a wafer is favorable, a yield will become high and productivity will improve.

In particular, in the present situation, a wafer mainly having a diameter of 300 mm is the object, but in the future, plasma processing will be performed on a wafer having a diameter of 450 mm. FPD substrates are also being enlarged year by year, and plasma processing will also be performed on these substrates. Therefore, in order to improve the yield and productivity, the uniformity of plasma in a large area will be more important. In this embodiment, the number n (n? 1) of the intermediate coils is increased in accordance with the size of the object to be enlarged. In this manner, the shape of the high frequency antenna 120 is optimized so that the plasma density does not decrease between the outer circumferential side and the inner circumferential side.

(Power division / impedance adjustment)

In addition, the high frequency power applied to each coil is divided by the power divider 130 at a desired ratio. An impedance adjusting function of the high frequency antenna 120 will be described with reference to FIG. 4.

4 shows an equivalent circuit of the feed portion of the high frequency antenna 120. As described above, the high frequency output from the first high frequency power supply 140 is supplied to the outer coil 120a, the intermediate coil 120b, and the inner coil 120c via the matching unit 135. The outer coil 120a is directly supplied with high frequency power. The intermediate coil 120b is supplied with a high frequency power via a variable impedance circuit (for example, a variable capacitor) 130a. The inner coil 120c is supplied with high frequency power via a variable impedance circuit (for example, a variable capacitor) 130a and a variable impedance circuit (for example, a variable capacitor) 130b.

The adjustment method of the impedances Zo, Zc, Zi of the outer coil 120a, the intermediate coil 120b, and the inner coil 120c is described. Since the outer coil 120a is formed only of the coil, the impedance Zo takes a fixed value. The impedance Zc of the intermediate coil 120b can be changed by changing the capacitance of the variable impedance circuit 130a. The impedance Zi of the inner coil 120c can be changed by changing the capacitances of the variable impedance circuit 130a and the variable impedance circuit 130b, respectively.

The high frequency current Ii, the high frequency current Ic, and the high frequency current Io change according to the ratio of the impedance Zi, the impedance Zc, and the impedance Zo. By using this, in the present embodiment, the capacitances of the variable impedance circuit 130a and the variable impedance circuit 130b are respectively controlled in accordance with the command of the control device 220. Thereby, the ratio of each impedance Zi, Zc, Zo is changed by changing impedance Zi and impedance Zc. Thereby, the ratio of the high frequency currents Ii, Ic, and Io which flow through each coil can be adjusted.

On the peripheral side of the wafer W, the plasma density decreases because electrons or ions in the plasma touch the wall and disappear. In consideration of this, the high frequency power of the largest high power is input to the outer coil 120a so that the outer plasma density is the highest. The remaining high frequency power divided by the power divider 130 is divided into the inner coil 120c and the intermediate coil 120b and input. In this manner, the three coils 120a to 120c and the power splitter 130 of the high frequency antenna 120 can adjust the inductive coupling state of the high frequency antenna 120 and the plasma. As a result, it is possible to control the plasma density at the outer side of the plasma excitation region to be slightly higher than the overall plasma density, and to prevent the decrease in the plasma density at the intermediate portion between the inner side and the outer side, thereby achieving the uniformity of the plasma as a whole. As a result, in-plane uniformity of the processing of the object can be maintained.

In particular, there is a demand from a user to perform various processes in one chamber recently. However, in the conventional plasma processing apparatus, the uniformity of the plasma is changed by the kind of gas, the pressure, and the RF power for each plasma process, and it is difficult to secure the uniformity. On the other hand, according to the plasma processing apparatus according to the present embodiment, if power division control according to a process is performed on an antenna having three zones or more, proper power supply is possible according to various processes, thereby ensuring uniformity of plasma for each process. Can be.

(Feedback control)

The control apparatus 220 may feedback-control the ratio of the high frequency electric power applied to each coil. In this case, measuring devices 250a, 250b, and 250c are connected to the feed rods 125a, 125b, and 125c to measure at least one of high-frequency current, voltage, and phase flowing through the coils 120a, 120b, and 120c. It is supposed to be.

The control device 220 controls the power ratio divided by the power splitter 130 based on the current, voltage, and phase of the high frequency measured by the measuring devices 250a to 250c. More specifically, the control device 220 determines how high-frequency power is applied to the coil from the current, voltage, and phase flowing through the coils 120a, 120b, and 120c. P = VI x cosθ (V: voltage, Calculated based on I: current and θ: phase, the feedback control of the variable impedance circuits 130a and 130b is made such that the difference between the high frequency power to be applied to each of the coils 120a to 120c and the current being supplied is small. As the measuring devices 250a to 250c, a voltmeter, a probe, and a CT (Current Transfer) are used.

According to the above feedback control, as shown in FIG. 3A, the nonuniformity of the plasma density can be corrected as in the curve Np-> curve Nc-> curve Nu to generate a more uniform plasma.

In addition, the control apparatus 220 may have the memory 220b, and may control the power ratio divided by the power division part 130 according to the recipe previously memorize | stored in the memory 220b. In this case, a plurality of recipes for controlling the power ratio divided by the power dividing unit 130 are stored in the memory 220b in advance. In the recipe, the capacitances of the variable impedance circuits 130a and 130b are preset. The CPU 220a selects a recipe matching a process to be executed in the future and controls the respective capacities of the variable impedance circuits 130a and 130b according to the recipe.

In an inductively coupled plasma processing apparatus, the symmetry of the apparatus becomes important in order to supply energy uniformly to the plasma in that high frequency electromagnetic fields are used to generate the plasma. Therefore, in this embodiment, as shown in Figs. 1 and 2, the variable impedance circuits 130a and 130b are arranged in series on the center axis O of the apparatus, and are high frequency antennas that are three coils installed in three zones. Symmetry between the 120 and the variable impedance circuits 130a and 130b is maintained. That is, the high frequency antenna 120 has symmetry with respect to the center axis O, and the power splitter 130 also has symmetry with respect to the center axis O.

(Blocking capacitor)

Blocking capacitors 145a to 145c are interposed in the terminal portions of the coils 120a to 120c. Referring to FIG. 3B, a blocking capacitor (V _p1 ) is applied to the voltage V _p1 of the feed points Sa, Sb, and Sc of the coils 120a, 120b, and 120c when the blocking capacitors 145a to 145c are not used. When 145a to 145c are used, the voltage V _p2 at the feed points Sa, Sb and Sc can be lowered to about half of the voltage V _p1 . Thereby, the top plate near the feed points Sa, Sb, and Sc can be avoided from being sputtered violently by the acceleration of electrons.

<Modification of the first embodiment>

5 to 7 show modifications of the first embodiment. Although the inside of the processing container 100 is omitted in the plasma processing apparatus 10 of FIGS. 5-7, it is the same structure as FIG. In the plasma processing apparatus 10 of FIG. 5, the feed point Sc of the inner coil 120c is disposed 180 degrees with respect to the feed points Sa and Sb of the outer coil 120a and the intermediate coil 120b. have. In the plasma processing apparatus 10 of FIG. 6, the intermediate coil 120b and the feeding points Sb and Sc of the inner coil 120c are disposed 180 degrees with respect to the feeding point Sa of the outer coil 120a. have.

In the plasma processing apparatus 10 of FIG. 7, the feed point Sc of the inner coil 120c is disposed 180 degrees with respect to the feed points Sa and Sb of the outer coil 120a and the intermediate coil 120b. have. In addition, in FIG. 5 and FIG. 6, the variable impedance circuits 130a and 130b are connected in series, whereas in FIG. 7, the variable impedance circuits 130a and 130b are connected in parallel. However, all have symmetry with respect to the central axis O.

According to the modification, the uniformity of the plasma can be improved by supplying the high frequency power of which power is appropriately divided into the high frequency antenna 120 having three or more zones.

&Lt; Embodiment 2 >

In general, in an inductively coupled plasma processing apparatus, (1) not only the plasma generation due to the acceleration of electrons using the electromagnetic energy from the high frequency antenna 120 is considered, but (2) the electrons coupled to the plasma through the capacitor are considered. It is necessary to aim at the uniformity of the plasma. Therefore, it is necessary to design the device in consideration of the capacitive component of (2) as well as the antenna design of (1).

In the plasma processing apparatus 10 according to the first embodiment, the uniformity of the plasma density with respect to the radial direction of the wafer W is achieved. That is, in the first embodiment, in consideration of (1), the high frequency antenna 120 is virtually divided into three zones, an outer zone, an inner zone, and an intermediate zone, and coils are provided in each zone, whereby Uniformity was increased.

In addition, in Example 1, the voltage at the feed point was lowered by using a blocking capacitor in consideration of (2). As a result, since the voltage at the feed point is high, the dielectric window 105 near the feed point is avoided from being attacked by the plasma.

In the second embodiment, the plasma density is uniform in the circumferential direction of the wafer W. That is, in the second embodiment, the uniformity of the plasma density in the circumferential direction is improved by arranging a plurality of feed points having symmetry.

A high-frequency antenna wound one coil or two or more layers has a voltage distribution that is asymmetric in the circumferential direction. 9 shows the distribution of the voltage V _pl of the coil when the coil was wound once (360 °). At this time, the voltage V _pl of the coil is the highest at the feed point P and gradually falls. Therefore, the plasma density in the circumferential direction is the highest at the feed point P and gradually lowers. Thus, just winding one coil in one layer cannot attain uniformity of plasma density in the circumferential direction.

Therefore, in this embodiment, two coils are provided in each zone to achieve uniformity of plasma density in the circumferential direction. 8A is a diagram schematically showing a longitudinal section of the plasma processing apparatus 10 according to the present embodiment. Although the inside of the processing container 100 is omitted in the plasma processing apparatus 10, it is the same structure as FIG. 1. 8B is a diagram schematically showing a power supply portion of the plasma processing apparatus 10 according to the present embodiment.

The outer coil of the outer zone is formed of two of the first outer coil 120a1 and the second outer coil 120a2. One end of the first outer coil 120a1 and the second outer coil 120a2 is connected to the feed rods 125a1 and 125a2 at feed points Sa1 and Sa2, respectively. The high frequency power output from the first high frequency power supply 140 is applied to the first outer coil 120a1 and the second outer coil 120a2 through the matching unit 135 and the feed rods 125a1 and 125a2. The first outer coil 120a1 and the second outer coil 120a2 are rounded in the same direction with respect to the central axis O, and then grounded through the blocking capacitors 145a1 and 145a2. The feed points Sa1 and Sa2 are disposed at points opposite to the central axis O, which are 180 degrees apart.

Returning to Figure 9, shows the distribution of the coil once (360 °) Voltage (V _pl2) of the distribution and the second outer coil (120a2) of the voltage (V _pl1) of the first outer coil (120a1) at the time the wound . At this time, the voltage (V _pl1) and voltage (V _pl2) of each coil is highest and gradually falls from the feed point (Sa1, Sa2). However, the voltages V _pl1 and V _pl2 at the feed points Sa1 and Sa2 are lower than the voltage V _pl at the feed point P when one coil is wound. In addition, the feed points Sa1 and Sa2 are 180 degrees apart. Therefore, the energy of the electromagnetic field generated around the two coils of the first outer coil 120a1 and the second outer coil 120a2 becomes uniform in the circumferential direction than the energy of the electromagnetic field generated around the one coil.

Similarly, the intermediate coil of the intermediate zone is formed of two of the first intermediate coil 120b1 and the second intermediate coil 120b2. One ends of the first intermediate coil 120b1 and the second intermediate coil 120b2 are connected to the feed rods 125b1 and 125b2 at feed points Sb1 and Sb2, respectively. The high frequency power output from the first high frequency power supply 140 passes through the feed rods 125b1 and 125b2 and is applied to the first intermediate coil 120b1 and the second intermediate coil 120b2. The first intermediate coil 120b1 and the second intermediate coil 120b2 are rounded and then grounded through the blocking capacitors 145b1 and 145b2.

Similarly, the inner coil of the inner zone is formed of two of the first inner coil 120c1 and the second inner coil 120c2. One end of the first inner coil 120c1 and the second inner coil 120c2 is connected to the feed rods 125c1 and 125c2 at feed points Sc1 and Sc2, respectively. The high frequency power output from the first high frequency power supply 140 passes through the feed rods 125c1 and 125c2 and is applied to the first inner coil 120c1 and the second inner coil 120c2. The first inner coil 120c1 and the second inner coil 120c2 are rounded and then grounded through the blocking capacitors 145c1 and 145c2.

As a result, the uniformity of the plasma density in the circumferential direction could not be achieved only by winding one coil in one layer, whereas the two coils were wound in the same direction to position the feed point of each coil 180 ° apart, As shown in FIG. 9, the uniformity of the voltage is improved in the circumferential direction of the two coils, thereby increasing the uniformity of the electric field energy introduced into the processing container 100. As a result, the attack force of the dielectric window 105 near the feed point is reduced, and the uniformity of the plasma density in the circumferential direction can be improved for each zone.

In the second embodiment, the uniformity of the plasma density in the radial direction by at least three zones and the power division described in the first embodiment can be achieved. As described above, in the plasma processing apparatus 10 according to the second embodiment, more uniform plasma can be generated over the entire plasma excitation region, and the plasma processing apparatus can also be enlarged.

In addition, the outer coil, the inner coil and the intermediate coil may each be formed of a plurality of coils, and each feed point of the plurality of coils forming the outer coil may be provided at a position symmetrical with respect to the central axis O. For example, in the high frequency antenna 120 of this embodiment, each coil enters from both sides, goes round, and ends in the ground, and the feed point has two points of symmetry of 180 degrees. In this case, the feeding point may be three points and may be 120 ° symmetrical, or the feeding point may be four points and 90 ° symmetry may be used.

The feed point of each coil may be arrange | positioned at intervals of any of 180 degrees, 120 degrees, 90 degrees, 72 degrees, and 60 degrees with respect to the center axis | shaft O. FIG. As the number of feed points arranged symmetrically increases, the plasma density becomes uniform in the circumferential direction, and the attack force of the dielectric window 105 near the feed point is reduced. In addition, as there are more feed points, not only the plasma distribution uniformity by the electromagnetic field distribution but also the plasma distribution uniformity by the capacitance distribution can be made uniform.

Third Embodiment

In the first embodiment, the variable impedance circuits (for example, variable capacitors) 130a and 130b in the power divider 130 were arranged symmetrically with respect to the central axis O. As shown in FIG. In contrast, in the third embodiment, the variable impedance circuits 130a and 130b are arranged asymmetrically with respect to the central axis O. In this case, as shown in FIG. 10, the space where the power divider 130 and the high frequency antenna 120 exist is shielded by the shield member 300. The shield member 300 is made of a conductive member such as aluminum. The high frequency antenna 120 is embedded in the antenna chamber 310.

Accordingly, asymmetrical coupling between the power splitter 130 and the high frequency antenna 120 may be avoided and symmetry of the stray capacitance component may be maintained. This makes it possible to prevent the generation of plasma from affecting the state of the magnetic field around the antenna and the like. In addition, the interference between the electric field between the power splitter 130 and the high frequency antenna 120 may be eliminated so as not to destroy the balance of voltage or amplitude in the antenna.

<Fourth Embodiment>

In the fourth embodiment, the coupling with the plasma is controlled by changing the distance between the high frequency antenna 120 and the plasma. 11A and 11B, there is one variable impedance circuit 130a of the power divider 130 and performs power division between the outer coil 120a2 and the intermediate coil 120b2. In this embodiment, the feed points are four of Sa1, Sa2, Sb1, and Sb2.

The intermediate coil 120b1 and the inner coil 120c1 are connected by the conducting wire 125c1. The intermediate coil 120b2 and the inner coil 120c2 are connected by the conducting wire 125c2. Blocking capacitors 145a1, 145a2, 145c1, and 145c2 are provided at the ends of the outer coils 120a1 and 120a2 and the inner coils 120c1 and 120c2.

The inner coils 120c1 and 120c2 are movable so that the distance from the dielectric window 105 is variable. The space 400 is formed between the inner coils 120c1 and 120c2 and the dielectric window 105.

According to this, when the high frequency antenna 120 is lowered, since the distance to the plasma is closer, the acceleration of the electrons is improved. On the other hand, when the high frequency antenna 120 is raised, the distance from the plasma becomes farther, and thus the acceleration of electrons becomes worse.

An effect equivalent to changing the power ratio of the coil and the coil is obtained according to the perspective of the distance between the dielectric window 105 and the coil. For example, by making the distance between one coil and the plasma larger than the distance between the other coil and the plasma, even if the same current flows, the degree of coupling between the coil and the plasma becomes smaller than that between the coil and the plasma.

In the above, the inner coils 120c1 and 120c2 are movable, but at least one of the outer coils 120a1 and 120a2, the intermediate coils 120b1 and 120b2, and the inner coils 120c1 and 120c2 has a distance from the dielectric window 105. It may be movable so that it may become variable. All of the outer coil, inner coil and intermediate coil may be movable.

In addition, a dielectric may be interposed in the space 400 between the high frequency antenna 120 and the dielectric window 105, or the space 400 may be filled with galden. Reducing the distance between the high frequency antenna 120 and the dielectric window 105, interposing a dielectric material therebetween, filling the space 400 between the high frequency antenna 120 and the dielectric window 105 with galden, etc. It is a method of changing a capacitive distribution without using a capacitor | condenser by adding capacitive component in all. The intervening dielectric should have a higher dielectric constant.

In addition, by changing the thickness of the dielectric between the high frequency antenna 120 and the dielectric window 105, the coupling state with the plasma may be changed. It is inexpensive because a simple mechanism can change the distribution of plasma.

<Fifth Embodiment>

In the fifth embodiment, in addition to the first high frequency power source 140, as shown in FIG. 12, a second high frequency power source 141 for outputting a desired high frequency frequency is provided. In this embodiment, the first high frequency power supply 140 is connected to the outer coil 120a via the matching unit 135. The second high frequency power supply 141 is connected to the inner coil 120c and the intermediate coil 120b via the matching unit 136. The variable impedance circuit 130a divides the high frequency power output from the second high frequency power supply 141 into a desired ratio and supplies the power to the inner coil 120c and the intermediate coil 120b.

According to this embodiment, the controllability is improved in the process of applying the optimum power by each of the three zones, thereby enabling high-precision power division.

In the present embodiment, the outer coil 120a is connected to the first high frequency power supply 140 and the remaining two coils (inner coil 120c and the intermediate coil 120b) are connected to the second high frequency power supply 141. However, the present invention is not limited thereto, and any one of the outer coil 120a, the inner coil 120c, and the intermediate coil 120b is connected to the first high frequency power supply 140 and not connected to the first high frequency power supply 140. Coils may be connected to the second high frequency power supply 141.

Sixth Embodiment

In the sixth embodiment, as shown in Fig. 13, in addition to the first high frequency power source 140, second and third high frequency power sources 141 and 142 which output a desired high frequency are provided. In this embodiment, the first high frequency power supply 140 is connected to the outer coil 120a via the matching unit 135. The second high frequency power supply 141 is connected to the intermediate coil 120b via the matching unit 136. The third high frequency power supply 142 is connected to the inner coil 120c via the matching unit 137.

As such, in the present embodiment, any one of the outer coil 120a, the inner coil 120c, and the intermediate coil 120b is connected to the first high frequency power supply 140 and is not connected to the first high frequency power supply 140. One of the remaining two coils is connected to the second high frequency power supply 141, and the other of the remaining two coils is connected to the third high frequency power supply 142.

According to this embodiment, the controllability is improved in the process of applying the optimum power by each of the three zones, thereby enabling high-precision power division.

As described above, according to each embodiment, high frequency power is input to the antenna having three or more zones by varying the power input ratio by the variable capacitor. This divides the power supplied to each winding coil. Thereby, the uniformity of the plasma in the radial direction of the wafer W can be aimed at.

In addition, by providing a plurality of feed points symmetrically for each antenna (coil) in each zone, the uniformity of the plasma in the circumferential direction of the wafer W can be achieved. If a plurality of power supplies are used for each coil, the cost is high, but if the power input to each coil is divided using the power divider 130, the cost is low.

As mentioned above, although preferred embodiment of this invention was described in detail with reference to an accompanying drawing, it cannot be overemphasized that this invention is not limited to this example. Those skilled in the art to which the present invention pertains will obviously be able to derive various modifications or modifications within the scope of the technical idea described in the claims. It is understood to belong to the technical scope of the invention.

For example, the number of windings of the coil in each zone of the high frequency antenna according to the present invention may be wound two or more times in a planar shape, or the coils may be arranged vertically.

Although not shown, when the gas is discharged into the processing container, the flow rate of the gas or the kind of gas may be controlled in a concentric multi-zone consisting of an outer zone, an inner zone, and an intermediate zone.

In addition, the plasma processing apparatus of this invention is not limited to an etching apparatus, What is necessary is just an apparatus which performs plasma processing, such as ashing, surface modification, CVD (Chemical Vapor Deposition).

In addition, the object to be plasma-processed by the plasma processing apparatus of the present invention is not limited to a silicon wafer, and may be a substrate for flat panel display (FPD), a substrate for a solar cell, or the like. Examples of the FPD include a liquid crystal display (LCD), a light emitting diode (LED) display, an electro luminescence (EL) display, a fluorescent fluorescence display (VFD), a plasma display panel (PDP), and the like.

10: plasma processing device
100 processing container
105: dielectric window
115: gas source
120: high frequency antenna
120a, 120a1, 120a2: outer coil
120b, 120b1, 120b2: middle coil
120c, 120c1, 120c2: inner coil
125a, 125b, 125c: feed rod
130: power divider
135, 136, 137, 155: matching device
130a, 130b: variable impedance circuit
140: first high frequency power supply
160: high frequency bias power supply
141: second high frequency power supply
142: third high frequency power supply
145a, 145a1, 145a2: blocking capacitor
145b, 145b1, 145b2: blocking capacitor
145c, 145c1, 145c2: blocking capacitor
150: wit
220: control unit
250a, 250b, 250c: measuring instrument
300: shield member
310: antenna chamber

Claims (16)

A processing container in which a plasma processing is performed on the target object inside;
A first high frequency power source for outputting high frequency power,
A high frequency antenna in which an outer coil, an inner coil and n intermediate coils (n is an integer of 1 or more) provided in a concentric shape with respect to a central axis outside the processing container;
And a dielectric window provided in an opening of the processing container and introducing a energy of an electromagnetic field generated from the high frequency antenna into the processing container. The method of claim 1,
And a power dividing unit provided between at least the outer coil and the inner coil and dividing the high frequency power output from the first high frequency power supply in a desired ratio to supply the coils to the respective coils. The method of claim 2,
And the power dividing unit is provided between the coils and divides the high frequency power output from the first high frequency power supply in a desired ratio to supply the coils to the respective coils. The method of claim 1,
At least one of the coils is movable so that a distance from the dielectric window is variable. The method of claim 4, wherein
In the case where the power divider is not provided between two coils, one of the two coils is movable. The method of claim 2,
And two or more power division units are provided symmetrically with respect to the central axis. The method of claim 2,
The power divider is provided two or more asymmetrically with respect to the central axis,
And a space in which the power splitter and the high frequency antenna exist is shielded by a shield member. The method according to any one of claims 1 to 7,
The outer coil, the inner coil and the intermediate coil are each formed of a plurality of coils,
Each feed point of the plurality of coils forming the outer coil is provided at a position symmetrical with respect to the central axis,
Each feed point of the plurality of coils forming the intermediate coil is provided at a position symmetrical with respect to the central axis,
And a feed point of each of the plurality of coils forming the inner coil is provided at a position symmetrical with respect to the central axis. The method of claim 8,
The feed point of each coil is disposed at any one of the interval of 180 °, 120 °, 90 °, 72 °, 60 ° with respect to the central axis. The method of claim 1,
And a blocking capacitor is respectively disposed in each of the coils. The method of claim 2,
And the power splitter has a variable capacitor and is provided with two or more. The method of claim 2,
A measuring device for measuring at least one of a high frequency current, a voltage, and a phase supplied to each of the coils;
And a control device for controlling the power ratio divided by the power divider based on at least one of high current, voltage, and phase measured by the measuring device. The method of claim 12,
And the control device has a memory and controls a power ratio that is divided into the power divider according to a recipe previously stored in the memory. The method of claim 1,
And a second high frequency power source for outputting high frequency power,
Any one of the outer coil, the inner coil and the intermediate coil is connected to the first high frequency power source,
The remaining two coils not connected to the first high frequency power supply are connected to the second high frequency power supply,
And a power dividing unit for dividing the high frequency power output from the second high frequency power supply into a desired ratio and supplying the remaining two coils. The method of claim 14,
The first high frequency power supply is connected to the outer coil,
And the second high frequency power supply is connected to the inner coil and the intermediate coil. The method of claim 1,
2nd and 3rd high frequency power supply which outputs a high frequency power,
Any one of the outer coil, the inner coil and the intermediate coil is connected to the first high frequency power source,
One of the remaining two coils not connected to the first high frequency power supply is connected to the second high frequency power supply, and the other of the remaining two coils is connected to the third high frequency power supply.

Images