JP3868620B2 - Plasma generator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma generator suitable for efficiently performing plasma processing such as etching, film formation, and ashing in high-precision manufacturing processes such as IC and LCD, and more specifically, plasma generation that uniformly supplies high-quality plasma. Relates to the device.
[0002]
[Prior art]
Conventionally, as a plasma generator used for plasma processing such as CVD, etching, ashing, etc., plasma generation is insufficient when only plasma is applied to an electric field. Therefore, a high-density plasma (HDP) is generated by sealing the plasma by applying a magnetic field. MRIE (magnetron reactive ion etcher) and the like are known. There is also known an apparatus which attempts to prevent damage by uniformizing a magnetic field using a planar coil as described in JP-A-3-79025.
[0003]
Furthermore, the plasma space is separated into a plasma processing space and a plasma generation space that communicate with each other in order to reduce damage to the object due to ions and prevent the object from being directly exposed to the high-density plasma being generated. Plasma with high-density plasma in a strong magnetic field such as ECR (Electron Cyclotron Resonance) or those in which both spaces are separated from each other, such as those described in JP-A-4-81324, ICP (Inductive Coupled Plasma), etc. It is the same in that the plasma generation space is confined to the plasma generation space adjacent to the processing space and the plasma generation space is adjacent to the plasma processing space. There are also known devices that confine high-density plasma using polarized electromagnetic waves.
[0004]
On the other hand, since it is difficult to uniformly supply plasma in a single plasma generation space as the processing target such as a liquid crystal substrate is enlarged and the plasma processing space is expanded, as described in JP-A-8-222399, In some cases, a plurality of plasma generation spaces are provided, and a control valve is provided for each of them to supply reaction gas and processing gas. In this case, the plasma generation space is divided into vertical cylindrical spaces so that the opening area does not decrease even if the number of plasma generation spaces is increased. Each side surface is surrounded by a high-frequency coil for excitation, and the magnetism for sealing the plasma is cylindrical. It is sent from the upper and lower end surfaces.
[0005]
[Problems to be solved by the invention]
By the way, in these conventional plasma generators, the plasma space is separated into the plasma generation space and the plasma processing space to reduce plasma damage and charge-up, but the distance between the plasma generation space and the plasma processing space is not so great. If they are separated from each other, ion species are suppressed more than necessary, while if both spaces are adjacent to each other, more gas flows backward from the plasma processing space to the plasma generation space. Such a backflow gas also contains components that should be discharged immediately, such as those generated by processing the object to be processed. When this gas enters the plasma generation space, it is violently decomposed and ionized by the high-density plasma, causing contamination, etc. It is inconvenient because it often changes to an undesirable one.
[0006]
This is not solved even if the plasma generation space is made plural, if the opening area from the plasma generation space to the plasma processing space remains the same. Further, it is sufficient for high-density plasma to interpose a magnet or the like between the plasma generation space and the plasma processing space in order to apply a static magnetic bias for sealing the plasma from above and below the plasma generation space. If it is going to secure magnetic force, processing and mounting of a magnetic member will become troublesome.
[0007]
On the other hand, the same applicant effectively prevents undesired gas inflow from the plasma processing space to the plasma generation space, and can easily mount the magnetic member and the like so that the magnetic member can be easily mounted. The structure of the member has been devised (Japanese Patent Application No. 9-159190, Japanese Patent Application No. 9-250111, etc.). Specifically, the magnetic member is arranged so that the plasma generation space is linearly distributed along the adjacent surface to the plasma processing space and the plasma generation space is sandwiched between them.
[0008]
However, when the plasma generation spaces are dispersed, the plasma generation efficiency does not always match even if the spatial sectional shape, the magnet shape, and the like are unified. The generation efficiency varies depending on various factors such as the arrangement state of the linear space and the variation in applied power for exciting the plasma. Further, even if the plasma generation efficiency at the various locations is consistent, the plasma density is often uneven or inclined depending on where the exhaust port is provided in the plasma processing space.
[0009]
For this, it is also conceivable to divide the application of electric power and supply of plasma generating gas into small openings and adjust the applied electric power and plasma generating gas for each place.
However, these adjustments usually have other roles such as control of the ion-to-radical concentration ratio, and the variables and changes in plasma generation efficiency are not generally linearly related to such adjustments. There are only a few situations where the adjustment can work effectively.
[0010]
Therefore, it is an issue to correct the non-uniformity of the plasma density caused by the variation in the plasma generation efficiency in the dispersed plasma generation space and the plasma flow in the plasma processing space without depending on the applied power or plasma generation gas. It becomes.
The present invention has been made to solve such problems, and an object of the present invention is to realize a plasma generator that uniformly supplies high-quality plasma.
[0011]
[Means for Solving the Problems]
About the 1st thru | or 2nd solution means invented in order to solve such a subject, the structure and effect are demonstrated below.
[0012]
[First Solution]
The plasma generator of the first solving means includes a first mechanism in which a plasma processing space is formed, and a second mechanism in which a plasma generation space is formed by being attached to or integrated with the first mechanism. In the plasma generator in which the plasma generation space is adjacent to and communicates with the plasma processing space, the plasma generation space is formed in a linear shape, and sandwiches the plasma generation space, Magnetic force is generated in the plasma generation space A magnetic member is attached, and a (single or plural) communication path extending member that extends the communication path between the plasma generation space and the plasma processing space is added to the plasma processing space side. The communication path extending member is adjusted to a different thickness depending on the location. It is characterized by.
[0013]
Here, the above-mentioned “form in a line” means that a single straight line, a curved line, a broken line, etc. are formed, and in addition to this, a plurality or a mixture of them is a plasma processing space. It is also distributed when it is distributed in the adjacent part / communication part, and it is also applicable to the case where a ring, circle, polygon, spiral is concentric or non-concentric, many are arranged in a row, or are widely formed independently. That means
In addition to the permanent magnet, the “magnetic member” includes a member formed by a DC exciting coil.
[0014]
In such a plasma generator of the first solution, by maintaining the conditions of separation of the plasma space and adjacent communication, plasma damage and charge-up are reduced, and the radical species component and ion species in the plasma are reduced. We are responding to the basic request of optimizing the ratio with other ingredients. In addition, the magnetic members attached so as to sandwich the plasma generation space are necessarily provided on the same side of the second mechanism as the plasma generation space along the adjacent surface to the plasma processing space, so that the magnetic force can be strengthened. In addition, the cross-sectional area of the plasma generating space itself along the surface adjacent to the plasma processing space and the plasma processing space is necessarily smaller than that of the plasma processing space at least by the amount occupied by the magnetic member. If there is a difference between the areas of the two spaces in this way, the ratio of the area of the communication adjacent surface and the cross-sectional area of the plasma processing space along this is the first ratio, and the area of the communication adjacent surface and the plasma generation space along this area. The first ratio is less than 1 and smaller than the second ratio, where the ratio of the cross-sectional area is the second ratio.
[0015]
When the first ratio is less than 1, the amount of gas flowing from the plasma processing space into the plasma generation space decreases. On the other hand, when the second ratio is 1, the amount of gas flowing out from the plasma generation space to the plasma processing space does not decrease. Further, even when the second ratio is less than 1 and the amount of outflow gas decreases, if the second ratio is greater than the first ratio, the degree of decrease may be small. In any case, the ratio of the gas flowing out from the plasma generation space into the plasma processing space is relatively higher than the ratio of the gas flowing into the plasma generation space from the plasma processing space. This not only suppresses the flow of undesired gas into the plasma generation space, but even when the gas enters the plasma generation space, the gas is quickly discharged into the plasma processing space together with the plasma flow. , Gas alteration due to high-density plasma can be prevented and suppressed.
[0016]
In addition, the high-quality plasma generated in this way is confined in the plasma generation space for a long time by the magnetic force of the magnetic member sandwiching the plasma generation space, and the density increases, but the magnetic force is concentrated in the plasma generation space and adjacent plasma processing It is weak in space. For this reason, when the high-density plasma flows out from the plasma generation space to the plasma processing space, the high-density plasma is released from the magnetic force restriction and diffuses after passing through the communication passages in both spaces. The plasma component diffused at the passage extension portion collides with the wall surface of the communication passage extension portion, that is, the communication passage extension member, and loses energy. In addition, the ratio of such plasma components is determined depending on the length of the communication path extending portion.
[0017]
Thereby, it is possible to finely adjust the amount of plasma supplied from the plasma generation space to the plasma processing space simply by changing the thickness of the communication path extending member. Therefore, there is no need to adjust the applied power or plasma generation gas, and the plasma generation efficiency varies in the dispersed plasma generation space, and the plasma density is not uniform due to the plasma flow in the plasma processing space. Correctly, the plasma density in the plasma processing space can be made uniform.
[0018]
Furthermore, since it is sufficient to arrange small pieces of magnetic members along the linear plasma generation space, it is sufficient to make a rod-like object that is relatively easy to manufacture in advance and cut it into small pieces. As a result, the manufacture of a magnetic member or the like is facilitated. In addition, since the magnetic member is provided on the same second mechanism side as the plasma generation space, there is no need to interpose between the plasma generation space and the plasma processing space, so that layout design, mounting work, and later components are eliminated. Maintenance work such as replacement is also easier.
[0019]
Therefore, according to the present invention, it is possible to realize a plasma generator that uniformly supplies high-quality plasma.
[0020]
[Second Solution]
A plasma generator of the second solution means (as described in claim 2 at the beginning of the application) is the plasma generator of the first solution means, wherein the communication path extending member is connected to the second mechanism. On the other hand, it is detachably mounted.
[0021]
In such a plasma generating apparatus of the second solution means, the degree of extension of the communication path by the communication path extending member is determined when the processing object after the plasma processing is examined and the uniformity of the processing is insufficient. Although the fine adjustment is performed, since the communication path extending member and the second mechanism are detachable, the adjustment of the adjustment operation is performed by removing the communication path extending member from the second mechanism. It is possible to perform additional machining or the like. Moreover, if the processing uniformity appears on the object to be processed as a moire image by irradiation of parallel light, the state of the processing surface of the object to be processed and the adjustment location of the communication path extending member are in a one-to-one relationship. Therefore, even if the adjustment to the communication path extending member is local or dissipated, adjustment work such as additional work is intuitive and easy.
[0022]
Thereby, even if the communication path extending member is added to the plasma processing space side, fine adjustment can be easily performed based on intuition.
Therefore, according to the present invention, it is possible to realize a plasma generator that can be easily adjusted when uniformly supplying high-quality plasma.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
The plasma generator of the present invention achieved by such a solution is generally used by being mounted in an appropriate vacuum chamber. For this purpose, each mechanism such as the first mechanism in which the plasma processing space is formed and the second mechanism in which the plasma generation space is formed has a balance between the ease of incorporation into the vacuum chamber and the necessity of the degree of vacuum. In many cases, it is attached separately after being formed from the standpoint of, for example, but it is often closely attached and fixed, but part or all of the same or a single member such as a clad material is used. It may be integrally formed by processing or the like.
[0024]
Hereinafter, specific embodiments for implementing such a plasma generator will be described with reference to the first and second embodiments. The first embodiment embodies the first and second solving means described above. In addition, in the second embodiment, in order to further increase the uniformity, the plasma generation space extending linearly along the adjacent surface to the plasma processing space is widened toward the plasma processing space. It has become. In this case, when the plasma generated in the plasma generation space flows out toward the plasma processing space, it does not become a constricted jet state but expands in a fan shape or a trumpet shape. Then, the high-density plasma immediately diffuses in the plasma processing space and becomes homogeneous quickly, so that the plasma state in the plasma processing space is kept more uniform without unevenness.
[0025]
[First embodiment]
A specific configuration of the plasma generator according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a longitudinal sectional view of the main part including the plasma generation space in addition to the plasma generation space, FIG. 2 is a vertical sectional perspective view around the plasma generation space, and FIG. 3 shows one of the plasma generation spaces. It is an enlarged view.
[0026]
This plasma generator generally includes a first mechanism for securing a plasma processing space and its additional portion, a second mechanism for securing a plasma generation space and its additional portion, and an electric field or magnetic field applied to each plasma. And an application circuit section for the purpose.
In both the first mechanism and the second mechanism, when a rectangular object such as a liquid crystal substrate is processed, a main part is formed in a substantially rectangular shape, but here, a round object such as an IC silicon wafer is formed. A case where the main part is formed in a substantially round shape, a cylindrical shape, or an annular shape in order to process a processed object will be described (see FIG. 2).
[0027]
In the first mechanism, a metal anode portion 11 is disposed on the upper side, and a metal cathode portion 12 that is insulated on the upper surface is disposed on the lower side for mounting the workpiece 1 such as a wafer. A plasma processing space 13 for the low temperature plasma 10 is formed at the sandwiched position (see FIG. 1). In addition, the anode portion 11 is previously formed with a plurality of communication ports 14 penetrating therethrough and a processing gas supply port 15 opening toward the plasma processing space 13 is also formed (FIGS. 1 to 1). (See FIG. 3). In this example, the ratio of the cross-sectional area of the communication port 14 to the effective cross-sectional area of the plasma processing space 13, that is, the first ratio is 0.05. The processing gas B supplied to the plasma processing space 13 through the processing gas supply port 15 is supplied by mixing a suitable amount of diluent gas with a reactive gas such as CF gas or silane gas. It is also.
[0028]
The second mechanism is mainly composed of a plasma generation chamber 21 made of an insulating material such as ceramic. The plasma generation chamber 21 has a plurality of (four in FIG. 1) annular grooves that form plasma generation spaces 22 concentrically. It is engraved and formed. Thereby, the plasma generation space 22 is dispersed in a linear shape. The plasma generation chamber 21 is fixed in a state where the opening side (the lower surface in the longitudinal sectional view) of the plasma generation space 22 is in close contact with the upper surface of the anode portion 11. At that time, alignment is performed so that the opening of the plasma generation space 22 overlaps the communication port 14 of the anode portion 11. As a result, the plasma generation space 22 and the plasma processing space 13 are adjacent to and communicated with each other, and the plasma generation space 22 extends linearly along the adjacent surface to the plasma processing space 13. In this example, the ratio between the cross-sectional area of the communication port 14 and the cross-sectional area of the plasma generation space 22, that is, the second ratio is 0.5. Note that these ratio values can be freely changed as long as the magnitude relationship is not reversed.
[0029]
In the plasma generation chamber 21, a plasma gas supply path 23 is also formed in an annular shape and a linear shape by a gas distribution member 21 a attached to the deeper part of the plasma generation space 22 (upward in the longitudinal sectional view). Are connected by a large number of small holes, and the plasma generation space 22 is supplied with the plasma generating gas A from the bottom (upward in the longitudinal sectional view) to generate the high-density plasma 20 and the plasma processing space 14 through the communication port 14. It will be sent to 13. As the plasma generating gas A, an inert gas that does not chemically react, such as argon, is used.
[0030]
Further, the back surface (upper surface in the longitudinal sectional view) of the plasma generation chamber 22 is cut away so that the side wall and the bottom portion surrounding the plasma generation space 22 are left in the plasma generation chamber 21. Then, one permanent magnet 25b (lower side in the longitudinal sectional view of FIG. 3), the coil 24, and the other permanent magnet 25a (upper side in the longitudinal sectional view of FIG. 3) are sequentially stacked and packed therein. These magnetic members 25, that is, the pair of permanent magnets 25a and 25b, are packed between the concentric annular plasma generation spaces 22 to form an annular shape, but are divided into small pieces in order to cut off the undesired induced current in the annular shape. ing. A large number of permanent magnet pieces 25 are arranged along the side wall of the plasma generation space 22, thereby forming an annular magnetic circuit corresponding to the plasma generation space 22. Thereby, the magnetic member 25 is provided on the second mechanism side and attached to the plasma generation space 22 and extends linearly along the plasma generation space 22 and the adjacent surface of the plasma generation space 22 and the plasma processing space 13. It runs alongside the plasma generation space.
[0031]
The permanent magnet 25 has a height obtained by adding the coil 24 to the pair 25a, 25b substantially equal to that of the plasma generation space 22, and the magnetic poles are directed in the direction of the horizontal plasma generation space 22 (see FIG. 3). . The lower magnet 25b has a simple shape with a rectangular cross section, and is placed horizontally so as to be parallel to the top surface of the anode section 11 and the plasma generation chamber 21 which are cut out. The magnetization direction is also the same horizontal direction as the vertical symmetry axis in the cross section. The lower magnet 25b is made smaller.
[0032]
The upper magnet 25a is larger than that. This is also made of the same simple rectangular shape that is magnetized in the horizontal direction, but its both side surfaces are cut off diagonally to form a trapezoid whose section is inverted. And while the lower side is short, the upper side is made longer than the width of the lower magnet 25b. Thus, the magnetic member 25a has a side surface directed toward the plasma generation space 22 that is not parallel to the side wall surface of the plasma generation space and is not orthogonal to the adjacent surface of the plasma generation space and the plasma processing space. The shape is slanted. Although the magnetization direction is not inclined, the magnetic flux lines 26 from the vicinity of the upper side protrude strongly and widely based on the inclined shape, whereas the magnetic flux lines 26 from the vicinity of the lower side and the magnetic flux lines from the lower magnet 25b. 26 is relatively weak and narrow.
[0033]
The magnetic force state will be described in detail. Since the magnetic flux lines 26 that protrude from the lower half of the upper magnet 25a to the side in the figure pass near the coil 24 and return to the opposite side in the figure, the permanent line at the upper side in the figure. A magnetic peak is formed with the lower end of the magnet 25a at the top. A substantially similar magnetic peak is also formed at the upper end of the lower magnet 25b. Since the permanent magnet 25 is attached to both sides of the plasma generation space 22, four magnetic peaks are formed around the plasma generation space 22. Therefore, in the plasma generation space 22, a so-called magnetic basin (minimum point of magnetic field strength) surrounded by magnetic mountains is formed. Then, electrons are captured here. Although described as a potential field wind, it is actually a vector field, so it will be complicated to describe accurately. However, in general, electrons are sealed in a ring shape in the columnar / beam-like plasma generation space 22 as a whole. is there.
[0034]
Then, the magnetic flux lines 26 appearing from the upper half of the upper magnet 25a to the side in the figure are located on the opposite side while becoming dense in the plasma generation space 22 (upward in the figure) and in the plasma gas supply path 23. Returning, further, a part of the magnetic flux of the upper magnet 25a extends downward and wraps around the lower magnet 25b, so that the state of the overall magnetic force distribution in the longitudinal section is similar to an image in which the virtue is reversed. And tightly tightened in the back of the plasma generation space 22 and loosened and swelled in the middle of the plasma generation space 22 and squeezed slightly at the adjacent surface between the plasma generation space 22 and the plasma processing space 13, and finally the plasma It is in a state of being released at the processing space 13.
[0035]
Depending on how the magnetic fluxes from the upper and lower magnets 25a and 25b overlap, a plurality of locally small magnetic basins may be generated in addition to the above magnetic basin, which may undesirably contain electrons or plasma or plasma Although it causes a collision with the inner wall of the generation space 22, they are also located outside the plasma generation space 22. Then, the magnetic circuit surrounding the large magnetic basin at the center of the plasma generation space 22 is inclined such that the upper magnetic field is stronger and the lower magnetic field is weaker. The high-density plasma 20 composed of components that are not ionized or have a large mass even if ionized is likely to flow out from the plasma generation space 22 to the plasma processing space 13.
[0036]
An additional plate 110 (communication path extending member) is attached to the non-adjacent surface (the lower surface in the figure) of the both surfaces of the anode portion 11 to the plasma generation chamber 21. The additional plate 110 is made of a conductive material such as metal so as not to impair the function of the anode portion 11 as an electrode, and is processed into a slightly smaller disk shape so as to substantially cover the central portion of the lower surface of the anode portion 11. Formed (see FIG. 1). Then, the bolts 111 are attached to the anode part 11 in close contact with the bolts 111, but if the bolts 111 are removed, they are peeled off from the anode part 11. Thus, the additional plate 110 is detachably attached to the second mechanism from the plasma processing space 13 side.
[0037]
A similar communication port is formed through the additional plate 110 at a position that coincides with the communication port 14 of the anode unit 11 when mounted on the anode unit 11. Accordingly, the additional plate 110 becomes a communication path extending member that extends the communication path 14 between the plasma generation space 22 and the plasma processing space 13 by the communication port extension 114. In addition, a similar communication port is formed through the portion that coincides with the processing gas supply port 15 of the anode section 11, and the processing gas supply port 15 of the anode section 11 is also extended by the supply port extension section 115. Yes.
[0038]
Then, based on the fact that the density of the low temperature plasma 10 in the plasma processing space 13 is generally high in the central portion and tends to be low in the peripheral portion, the additional plate 110 is finished so that the central portion is thick and the peripheral portion is thin. As a result, the additional plate 110 changes such that the length of the supply port extension 115 is longer at the center and gradually becomes shorter from the center to the periphery.
[0039]
The application circuit unit is divided into a first application circuit centered on the RF power source 31 and a second application circuit centered on the RF power source 32.
The RF power supply 31 has a variable output power, and applies an alternating electric field to the grounded anode part and generates a bias voltage, so that its output is sent to the cathode part 12 via a blocking capacitor. (See FIG. 1). For this, a frequency of 500 KHz to 2 MHz is often used. As a result, the first application circuit applies an electric field that contributes to the enhancement of the low temperature plasma 10 to the plasma processing space 13 to some extent.
[0040]
The RF power source 32 also has variable output power, and drives both coils 24 sandwiching the plasma generation space 22 to apply an alternating magnetic field to the plasma generation space 22 (see FIG. 2). The maximum output power is large, and the frequency is often set to 13 MHz to 100 MHz. Thus, the second application circuit applies a magnetic field that contributes to generation and strengthening of the high-density plasma 20 to the plasma generation space 22.
[0041]
The use mode and operation of the plasma generator of the first embodiment will be described with reference to the drawings. FIG. 4 is a longitudinal sectional view showing a state where the vacuum chamber is mounted.
[0042]
Prior to use, the cathode 12 of the plasma generator is installed at the center of the box-shaped vacuum chamber body 2 with the top opened and supported by support legs 12a. The vacuum chamber main body 2 has a vacuum chamber lid 3 attached to the top so that it can be opened and closed, and a vacuum pump 5 such as a turbo pump is connected to the bottom or side through a variable valve 4 for vacuum pressure control. ing. The vacuum chamber main body 2 is attached with the plasma generation chamber 21 and the anode 11 and can be cooled with water. When the vacuum chamber main body 2 is closed, the inside of the vacuum chamber main body 2 as well as the plasma processing space 13 and the plasma generation space 22 are Sealed. Then, the vacuum pump 5 is operated, and the supply of the plasma gas A through the plasma gas supply path 23 and the supply of the processing gas B through the processing gas supply port 15 and the supply port extension 115 are started as appropriate. As a result, preparations for plasma processing are performed for the workpiece 1 mounted on the cathode portion 12.
[0043]
Next, when the RF power source 32 is operated, an RF electromagnetic field is applied to the plasma generation space 22 via the coil 24, and the electrons of the plasma gas A are vigorously moved. At this time, the electrons stay for a long time in the plasma generation space 22 by the action of the magnetic circuit by the permanent magnet piece 25, and fly around in the annular space while spirally exciting the plasma gas A. In this way, the high-density plasma 20 is generated, but since the electrons sealed in the plasma generation space 22 contain a large amount of high energy of 10 to 15 eV or more that greatly contributes to ionic species generation, the high-density plasma 20 Has a high ratio of ionic species components.
[0044]
In the high-density plasma 20 expanded in the plasma generation space 22, the radical species and ionic species components in particular try to jump out of the plasma generation space 22 due to the expansion pressure. When it is pushed back to the center and the expansion pressure increases, it flows out from the communication port 14 having a relatively weak magnetic force. When the expansion pressure is further increased, it quickly flows out from the communication port 14 and the communication port extension 114 to the plasma processing space 13. At that time, since the collision is suppressed by being pushed back against the inner surface and the bottom surface of the side wall of the plasma generation space 22 having a relatively strong magnetic force, energy loss due to the collision with the wall surface is reduced, and plasma generation efficiency is increased. Most of them flow out through the communication port 14 and the communication port extension 114.
[0045]
Thus, the high-density plasma 20 generated in the plasma generation space 22 is efficiently transferred to the plasma processing space 13 based on the expansion pressure and the gradient of the magnetic force distribution, but the magnetic flux lines that have reached the communication port 14. 26 is released at the communication port extension 114 from the restraint by 26. And the part which spreads from the advancing direction to the side, that is, the horizontal direction, but larger than the diameter of the communication port extension 114 (see the two-dot chain line portion in FIG. 3) collides with the inner wall of the communication port extension 114. As a result, the plasma energy is lost to the additional plate 110, and the plasma returns to a normal gas state at a considerable rate.
[0046]
When the communication port extension 114 is long, the ratio also increases. However, since the communication port extension 114 has a long central portion and a short periphery, the high-density plasma 20 generated in the plasma generation space 22 is plasma. At the time of supply to the processing space 13, the central portion is strongly suppressed, whereas the peripheral portion is supplied without being suppressed.
Thus, if the additional plate 110 is not provided, the density of the low-temperature plasma 10 in the plasma processing space 13 is higher in the central portion and lower in the peripheral portion. However, the high-density plasma 20 is mainly supplied to the peripheral portion. The plasma density in the plasma processing space 13 is made uniform over the entire area.
[0047]
When the RF power source 31 is operated, an RF electric field is also applied to the plasma processing space 13 via the anode part 11 and the cathode part 12. Since there is no magnetic circuit or the like for containing electrons, high-density plasma cannot be produced even when the processing gas B or the like is excited. When only the power from the RF power source 31 is used, the low temperature plasma 10 has a small number of electrons having energy of 10 to 15 eV or more, and therefore the ratio of the radical species component becomes high. However, in the case of the low-temperature plasma 10 in this apparatus, since the above-described high-density plasma 20 is mixed, the ratio of the actual radical species component to the ionic species component is any ratio between the two.
[0048]
When the output of the RF power source 32 is increased, electrons of 10 to 15 eV or more in the plasma generation space 22 increase. And the production amount of the high-density plasma 20 increases. As a result of the mixing, the ratio of the ion species component is raised in the low temperature plasma 10. On the other hand, when the output of the RF power source 32 is lowered, electrons of 10 to 15 eV or more in the plasma generation space 22 are reduced. And the production amount of the high-density plasma 20 decreases. As a result of the mixing, the ratio of the ion species component in the low temperature plasma 10 is lowered.
[0049]
Furthermore, when the output of the RF power supply 32 is slightly lowered while the output of the RF power supply 31 is increased, the following is obtained. First, as the output of the RF power source 31 is increased, the electron density in the plasma processing space 13 shifts to a higher density and higher energy side, and low-temperature plasma in the plasma processing space 13 increases. This increases the radical concentration there, but at the same time increases the ion ratio slightly. Next, as the output of the RF power source 32 is reduced, the electron density in the plasma generation space 22 is shifted to a low density and low energy side, and the high density plasma in the plasma generation space 22 is slightly reduced. As a result, the radical concentration and the ion ratio are lowered. However, since the high energy component is originally large, the ion ratio is greatly lowered even if the output is slightly reduced. When such a high-density plasma 20 is mixed with the low-temperature plasma 10 in the plasma processing space 13, the increase or decrease in the ion ratio is almost offset, while the radical concentration increases. That is, the plasma concentration of the low temperature plasma 10 is increased without much changing the ratio of the radical species component and the ion species component. Similarly, when the outputs of the RF power sources 31 and 32 are increased or decreased in the opposite direction, the plasma concentration of the low temperature plasma 10 is lowered.
[0050]
Thus, in the low temperature plasma 10, the ratio between the radical species component and the ion species component is easily variably controlled over a wide range. Further, in this apparatus, since the cross-sectional area of the plasma generation space 22 is much smaller than the cross-sectional area of the plasma processing space 13 and the first ratio is much smaller than the second ratio, the high-density plasma 20 In addition to being quickly sent out from the plasma generation space 22 to the plasma processing space 13, the amount of gas that flows back into the plasma generation space 22 from the plasma processing space 13 is small so that the processing gas B is directly excited by the high-density plasma 20. It is almost never decomposed or ionized until it is undesired.
[0051]
By the way, as a result of inspecting the workpiece 1 that has been subjected to such plasma processing, if the processing state is uneven and the uniformity is not satisfactory, fine adjustment is performed as follows. .
First, a place where the plasma processing is insufficient on the processing surface of the workpiece 1 is marked with appropriate shades. Then, the bolt 111 is removed to remove the additional plate 110 from the anode portion 11, and the mark of the workpiece 1 is transferred to the lower surface of the additional plate 110. Since this transfer does not require expansion / contraction, it can be easily performed using a soft film or the like. Then, additional processing is performed on the lower surface of the additional plate 110 using the transfer mark as a mark, and then the additional plate 110 is returned to the anode portion 11.
[0052]
Thus, by adjusting the thickness of each part of the additional plate 110, the plasma density distribution can be easily adjusted to be uniform, and the uniformity of the plasma processing can be improved.
In addition, when one adjustment is not enough, it is possible to ensure uniform plasma processing by repeating the same adjustment.
Note that the trapezoidal upper magnet 25a and the lower magnet 25b having a rectangular cross section are simple convex polygons and can be easily formed.
[0053]
[Second embodiment]
A second embodiment of the plasma generator of the present invention will be described. FIG. 5 is an enlarged vertical cross-sectional view of the main part, and corresponds to FIG. 3 described above.
The plasma generator differs from that of the first embodiment in that a pair of upper magnets 25c and 25d are provided in place of the upper magnet 25a, and the outer wall 21b of the plasma generation space 22 is inclined. The plasma generation space 22 formed is narrower toward the back (upward in the figure), and the side wall inside the plasma generation space 22 correspondingly has an inclined inner side surface 21c. The mouth 14 and the communication port extension 114 are greatly expanded, and the inner surface thereof is an extended surface of the inclined inner surface 21c. Thereby, the plasma generation space is expanded toward the plasma processing space including the adjacent portion and the communication portion.
[0054]
The upper magnet 25c is a vertically long, simple rectangular shape, and is magnetized so that the magnetization direction is horizontal in a straight state. The same applies to the upper magnet 25d, but they are arranged side by side when installed between the concentric annular plasma generation spaces 22, and are opposite to each other so that the lower part is narrow and the upper part is wide in a V shape. Set diagonally. As a result, these magnetic members 25c and 25d have their side surfaces directed toward the plasma generation space 22 not parallel to the side wall surface of the plasma generation space, but orthogonal to the adjacent surfaces of the plasma generation space and the plasma processing space. Further, the magnetization direction is not horizontal, and both the shape and the magnetization direction are inclined.
[0055]
In this case, the upper magnets 25c and 25d sandwiching the plasma generation space 22 from both sides and viewed from both sides are narrow in the shape of a letter C and wide in the lower part. While the lines are strong and dense, the magnetic flux lines are relatively weak and rough below the anode portion 11 side. Such a magnetic force inclination state is further emphasized by the fact that the magnetic flux lines come out obliquely from the upper magnets 25c and 25d.
[0056]
Thus, also in this case, the high-density plasma generated in the plasma generation space 22 is efficiently conveyed to the plasma processing space 13 based on the expansion pressure and the gradient of the magnetic force distribution.
In addition, since not only the lower magnet 25b but also the upper magnets 25c and 25d have a simple shape with a rectangular cross section, they can be easily manufactured.
[0057]
Further, since the plasma generation space is widened toward the plasma processing space including the adjacent portion and the communication portion, the inclination of the upper magnets 25c and 25d is further increased, and the plasma is generated from the plasma generation space 22 due to the inclination of the magnetic member. In addition to further enhancing the plasma supply efficiency to the processing space 13, the high-density plasma 20 is not restricted by the communication port 14 and the communication port extension 114 when flowing out from the plasma generation space 22 to the plasma processing space 13. It is carried from the beginning so as to follow the expansion of the inclined inner side surface 21c, the communication port 14, and the communication port extension 114.
[0058]
In addition, at that time, the high-density plasma 20 released from the magnetic force restriction at the communication port extension 114 spreads further to the side, so that even if the communication port extension 114 is not narrow, It collides with the inner wall of the communication port extension 114 at a ratio corresponding to the length, and the plasma is returned to the normal gas state (see the two-dot chain line in FIG. 5).
[0059]
Thus, the processing gas supply port 15 having a low plasma density and the function of finely adjusting the plasma supply amount from the plasma generation space 22 to the plasma processing space 13 in accordance with the length of the communication port extension 114 can be obtained. Since the high-density plasma flows obliquely into the portion immediately below the supply port extension 115 and is quickly mixed and diffused, the low-temperature plasma 10 in the plasma processing space 13 has few spots even in the vicinity of the anode portion 11, and is to be processed. In the vicinity of the cathode portion 12 where 1 is placed, a more uniform state is obtained.
As a result, even if a good quality plasma is efficiently supplied, the distribution state of the plasma is kept uniform, so that a good quality plasma treatment is efficiently performed.
[0060]
In the above embodiment, the inner diameter of the supply port extension 115 is the same as the inner diameter of the processing gas supply port 15, but the shape of the supply port extension 115 is not limited to this. The inner diameter of the extension 115 may be larger than the inner diameter of the processing gas supply port 15, or may be formed in a tapered shape or a trumpet shape.
Moreover, although the above-mentioned additional plate 110 consists of a single plate, a communicating path extending | stretching member is not limited to a single member, As long as the shape of the communicating path extension part 114 can be ensured, it will be several. It may be divided into pieces and provided separately for each communication port 14.
[0061]
【The invention's effect】
As is apparent from the above description, in the plasma generating apparatus of the first solving means of the present invention, the shape and arrangement of the plasma generating space and the magnetic member are devised and the plasma generating space and the plasma processing space are separated. By adjusting the plasma supply amount on the side of the plasma processing space where the cross-sectional area ratio changes and the magnetic force weakens, the flow of gas from the plasma processing space to the plasma generation space is prevented and high quality plasma is supplied and connected. Fine adjustment can be easily performed only by adjusting the extension of the passage, and as a result, there is an advantageous effect that a plasma generator that uniformly supplies high-quality plasma can be realized.
[0062]
Further, in the plasma generating apparatus of the second solving means of the present invention, fine adjustment can be easily performed on the basis of intuition even if a communication path extending member is added to the plasma processing space side. Thus, there is an advantageous effect that a plasma generator that can be easily adjusted when uniformly supplying a high-quality plasma can be realized.
[0063]
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of the main part of a plasma generator according to a first embodiment of the present invention.
FIG. 2 is a longitudinal sectional perspective view around the plasma generation space.
FIG. 3 is an enlarged view of one of the plasma generation spaces.
FIG. 4 is a cross-sectional view showing a mounting state in a vacuum chamber.
FIG. 5 is an enlarged vertical cross-sectional view of the plasma generation space of a second embodiment of the plasma generator of the present invention.
[Explanation of symbols]
1 Workpiece
2 Vacuum chamber body
3 Vacuum chamber lid
4 Variable valve
5 Vacuum pump
10 Low temperature plasma
11 Anode section (first mechanism; first application circuit)
12 Cathode (first mechanism; first application circuit)
13 Plasma processing space
14 Communication port (communication passage)
15 Processing gas supply port
20 High density plasma
21 Plasma generation chamber (second mechanism)
21a Gas distribution member (second mechanism)
21b Inclined outer surface
21c Inclined inner surface
22 Plasma generation space
23 Gas supply path for plasma
24 Coil (second application circuit)
25 Permanent magnet (Magnetic member for magnetic circuit)
25a Upper magnet
25b Lower magnet
25c Upper magnet
25d upper magnet
26 Magnetic flux lines (magnetic circuit)
31 RF power supply (first application circuit)
32 RF power supply (second application circuit)
110 Additional plate (communication path extending member)
111 bolts (fasteners, mounting means)
114 Communication port extension (Communication path extension)
115 Supply port extension
A Argon gas (non-reactive gas, plasma generating gas)
B CF gas (reactive gas, processing gas)

Claims (2)

A first mechanism in which a plasma processing space is formed; and a second mechanism attached to or integrated with the first mechanism to form a plasma generation space, wherein the plasma generation space is the plasma processing space. In a plasma generator adjacent to and communicating with a space,
The plasma generation space is formed in a linear shape,
In addition, a magnetic member for generating a magnetic force is attached to the plasma generation space across the plasma generation space, and
A communication path extending member for extending a communication path between the plasma generation space and the plasma processing space is added to the plasma processing space side, and the communication path extending member is adjusted to have a different thickness depending on a location. A plasma generator . The plasma generating apparatus according to claim 1 , wherein the communication path extending member is detachably attached to the second mechanism.

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