JP2015015342A - Plasma processing apparatus, and plasma distribution control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inductively-coupled plasma processing apparatus which enables the suppression of sputter erosion of a metal window owing to plasma, and the control of strength distribution of the plasma.SOLUTION: A plasma processing apparatus 100 for processing a substrate G by plasma comprises: a high-frequency antenna 11 for generating inductively coupled plasma in a plasma-generating region; and a metal window 3 disposed between the plasma-generating region and the high-frequency antenna 11, and isolated from a main body container. The metal window 3 has metal windows 30a-30d isolated from each other by an insulator; each of the metal windows 30a-30d is connected to the ground at a ground point.

Description

  The present invention relates to an inductively coupled plasma processing apparatus for performing plasma processing on a substrate such as a glass substrate used in a flat panel display (FPD) such as a liquid crystal display device, and a plasma distribution adjusting method in the plasma processing apparatus.

  In a manufacturing process of a liquid crystal display device or the like, various plasma processing apparatuses such as a plasma etching apparatus and a plasma CVD film forming apparatus are used to perform a predetermined process on a glass substrate. As such a plasma processing apparatus, there is an inductively coupled plasma (ICP) processing apparatus capable of obtaining high-density plasma.

  The inductively coupled plasma processing apparatus divides a processing chamber that accommodates a substrate to be processed and an antenna chamber disposed above the processing chamber with a dielectric window, a high-frequency antenna is disposed in the antenna chamber, and a processing gas is disposed in the processing chamber. And inductively coupled plasma is generated in the processing chamber by supplying high frequency power to the high frequency antenna, and the substrate to be processed is subjected to predetermined plasma processing by the generated inductively coupled plasma.

  Here, recently, the size of the substrate to be processed has been increased. For example, when a rectangular glass substrate for LCD is taken as an example, the length of the short side × long side is about 1500 mm × about 1800 mm. The enlargement is remarkable to a size of 2200 mm × about 2400 mm, and further to a size of about 2800 mm × about 3000 mm. When the substrate to be processed is increased in size as described above, it is necessary to increase the size of the processing chamber and the antenna chamber, and accordingly, it is necessary to increase the size of the dielectric window. In order to meet such a demand, a technique for increasing the size of the substrate to be processed has been proposed by increasing the strength by using a metal window made of a nonmagnetic metal material instead of the dielectric window.

  In this technology, an eddy current is generated on the upper surface of the metal window due to the current flowing in the high-frequency antenna, and the eddy current becomes a loop current that returns to the upper surface through the side and lower surfaces of the metal window. It has a mechanism different from the case of using a dielectric window in which plasma is generated by forming an induction electric field in the processing chamber (see, for example, Patent Document 1).

JP 2011-29584 A

  However, the above-described conventional technique has a problem in that the metal window is scraped by sputtering due to plasma due to the potential generated in the metal window, and the service life is shortened. Moreover, it is not easy to improve the distribution of the strength of eddy current generated for each metal window only by designing the shape of the metal window, and a technique for adjusting the distribution of the strength of the plasma is required.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an inductively coupled plasma processing apparatus that suppresses spattering of a metal window by plasma and enables adjustment of plasma intensity distribution, and a plasma distribution adjustment method using the plasma processing apparatus. It is in.

  In order to solve the above-mentioned problem, a plasma processing apparatus according to claim 1 is a plasma processing apparatus for plasma processing a substrate, wherein a high frequency antenna that generates inductively coupled plasma in a plasma generation region, the plasma generation region, and the high frequency The metal window is disposed between the antenna and the main body container and is insulated, and the metal window is composed of a plurality of metal windows insulated from each other by an insulator, and the plurality of metal windows are respectively It is characterized in that it is grounded at one grounding point.

  The plasma processing apparatus according to claim 2 is the plasma processing apparatus according to claim 1, wherein the one grounding point is provided at substantially the center of each of the outer peripheral side or the inner peripheral side of the plurality of metal windows. It is characterized by.

  The plasma processing apparatus according to claim 3 is the plasma processing apparatus according to claim 1 or 2, wherein the one ground point is grounded via a resistor.

  The plasma processing apparatus according to claim 4 is the plasma processing apparatus according to any one of claims 1 to 3, wherein the plurality of antenna chambers in which the high-frequency antenna is disposed and processing chambers including the plasma generation regions are the plurality. A container partitioned by a metal window, wherein the one grounding point is grounded by being connected to a side wall of the antenna chamber.

  The plasma processing apparatus according to claim 5 is the plasma processing apparatus according to any one of claims 1 to 4, wherein at least one of the plurality of metal windows is further at one ground point. By being ground-connected, it is characterized in that the ground connection is made at two ground points.

  The plasma processing apparatus according to claim 6 is the plasma processing apparatus according to claim 5, wherein the plurality of metal windows are arranged corresponding to the substrate having a rectangular shape, and the two grounding points are the plurality of grounding points. Among the metal windows, the metal window is provided at a position corresponding to the long side of the substrate.

  The plasma processing apparatus according to claim 7 is the plasma processing apparatus according to claim 5 or 6, wherein the two grounding points are not provided in each of the plurality of metal windows. It is provided in a region where a relatively large amount of eddy current flows.

  The plasma processing apparatus according to claim 8 is the plasma processing apparatus according to any one of claims 1 to 3, wherein two adjacent metal windows of the plurality of metal windows are connected via a capacitor. The one ground point provided in each of the two metal windows is electrically connected to form a current loop circuit.

  The plasma processing apparatus according to claim 9 is characterized in that, in the plasma processing apparatus according to claim 8, the capacitance of the capacitor is adjusted so that the reactance of the current loop circuit is negative.

  The plasma processing apparatus according to claim 10 is the plasma processing apparatus according to claim 8 or 9, wherein the capacitor is a metal window provided at a position corresponding to a corner of the substrate among the plurality of metal windows. It is connected to a position corresponding to a corner.

  The plasma processing apparatus according to claim 11 is the plasma processing apparatus according to any one of claims 8 to 10, wherein the antenna chamber in which the high-frequency antenna is arranged and a plurality of processing chambers including the plasma generation region are provided. A container partitioned by a metal window, wherein the one grounding point is connected to a ceiling wall of the antenna room.

  In order to solve the above-mentioned problem, the plasma distribution adjusting method according to claim 12 is characterized in that the plasma generation region and the high-frequency antenna are isolated by a plurality of metal windows insulated from the main body container and insulated from each other by an insulator. A plasma distribution adjustment method in a plasma processing apparatus for plasma processing a substrate by generating inductively coupled plasma in the plasma generation region by flowing a high frequency current through an antenna, wherein each of the plurality of metal windows is connected to a single ground point. It is characterized by ground connection.

  The plasma distribution adjustment method according to claim 13 is the plasma distribution adjustment method according to claim 12, wherein at least one metal window of the plurality of metal windows is further grounded at one point of ground. It is characterized in that it is grounded at the grounding point.

  The plasma distribution adjustment method according to claim 14 is the plasma distribution adjustment method according to claim 13, wherein the distance between the two grounding points is adjusted to adjust the distance between the two grounding points of the one metal window. It is characterized by adjusting the current flowing through the.

  15. A current loop circuit is formed by connecting two adjacent metal windows of the plurality of metal windows via a capacitor and electrically connecting a ground point provided on each of the two metal windows. It is characterized by doing.

  A plasma distribution adjusting method according to a sixteenth aspect is the plasma distribution adjusting method according to the fifteenth aspect, wherein the capacitance of the capacitor is adjusted so that reactance of the current loop circuit becomes negative.

  According to the present invention, the metal window disposed between the high-frequency antenna and the plasma generation region is constituted by a plurality of metal windows, and each metal window is connected to the ground at one point (GND connection). Thus, plasma can be generated without lowering the source efficiency, and the window potential of the metal window can be lowered, so that it is possible to suppress spattering of the metal window due to plasma. This also indicates that the plasma intensity is adjusted. In addition, by connecting the metal window to the ground at two grounding points, the magnitude of the eddy current flowing on the lower surface of the metal window can be adjusted, and thereby, in the plasma generation region corresponding to the two grounding points. The plasma intensity can be adjusted. Further, by connecting two adjacent metal windows via a capacitor and forming a current loop circuit, the eddy current flowing between the connection positions of the capacitor is increased, and the plasma in the corresponding plasma generation region is strengthened. be able to.

  As described above, according to the present invention, it is possible to control the distribution of the intensity of the plasma, and thereby it is possible to make the plasma treatment uniform on the substrate. Such an effect can be obtained particularly remarkably in plasma processing for a substrate having a side length of more than 1 m.

1 is a cross-sectional view showing a schematic structure of an inductively coupled plasma processing apparatus according to an embodiment of the present invention. It is a schematic plan view of the metal window with which the plasma processing apparatus of FIG. 1 is provided. It is a schematic diagram explaining the plasma production | generation principle in the plasma processing apparatus of FIG. It is a top view which shows the 1st and 2nd example of a connection of a metal window and a GND connection member in the plasma processing apparatus of FIG. FIG. 4 is a diagram showing a comparison between an electron density distribution when plasma is generated with the metal window of FIG. 4A in a float state and an electron density distribution when plasma is generated by connecting the corners of the metal window to GND. It is. FIG. 5 is a diagram showing an equivalent circuit when plasma is generated with the metal window of FIG. 4A electrically floated, and an equivalent circuit when plasma is generated by connecting the metal windows to GND. The figure which shows typically the electric potential (window electric potential) distribution between the A point and B point which were set to the metal window of FIG.4 (b) with the case where the metal window is made into the float state, and the case where it connects with GND. It is. It is a top view which shows the 3rd and 4th example of a connection with a metal window and a GND connection member in the plasma processing apparatus of FIG. It is a figure which shows the equivalent circuit corresponding to the 3rd and 4th connection example of FIG. It is a top view which shows the 5th example of a connection with a metal window and a GND connection member in the plasma processing apparatus of FIG. It is a figure which shows the equivalent circuit corresponding to the 5th example of a connection of FIG. It is a figure which shows the result of having simulated the distribution of the electric field strength ratio on the length axis shown in FIG. It is a figure which shows the result of having simulated the distribution of the electric field strength ratio on the length axis shown in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view showing a schematic structure of an inductively coupled plasma processing apparatus 100 according to an embodiment of the present invention. The plasma processing apparatus 100 is used for, for example, plasma processing such as etching of a metal film, ITO film, oxide film or the like when forming a thin film transistor on a glass substrate for a flat panel display (FPD), or ashing processing of a resist film. Can do. In addition, as FPD, a liquid crystal display, an electroluminescent display, a plasma display etc. are mentioned. Moreover, the plasma processing apparatus 100 can be used not only for the glass substrate for FPD but also for various plasma processes applied to the glass substrate for solar cell panel in the manufacturing process.

  The plasma processing apparatus 100 includes an airtight main body container 1 having a rectangular tube shape made of a conductive material, for example, aluminum having an alumite film formed on an inner wall surface by anodization. The main body container 1 is grounded (ground connection (hereinafter referred to as “GND connection”)) by a ground wire 2. The inside of the main body container 1 is connected to an upper antenna chamber 4 and a lower processing chamber 5 by a metal window 3. It is partitioned.

  FIG. 2 is a schematic plan view of the metal window 3. The metal window 3 in FIG. 1 shows a cross section taken along the line AA in FIG. The metal window 3 includes a support shelf 6 and a support beam 7 provided so as to protrude inside the main body container 1 between the side wall 4a of the antenna chamber 4 and the side wall 5a of the processing chamber 5 in the main body container 1, and a support shelf. 6 and four beam windows 30a to 30d mounted on the support beam 7 with an insulator 28 interposed therebetween.

  A plurality of metal windows 30a to 30d occupy most of the metal window 3 serving as a ceiling wall of the processing chamber 5. For example, a nonmagnetic metal is used for the metal windows 30a to 30d, and for example, aluminum or an aluminum alloy can be used. When the metal windows 30a to 30d are made of aluminum or aluminum alloy, at least the anodized film or the ceramic sprayed film, or the ceramic or quartz cover on the surface (lower surface) on the processing chamber 5 side in order to improve the corrosion resistance. Is preferably formed.

  Each of the metal windows 30a to 30d is electrically connected to a GND connection member 50 made of a highly conductive material such as a copper plate at one or two ground points in the window, and the other end of the GND connection member 50 Is electrically connected to the side wall 4 a of the antenna chamber 4 in the main body container 1. Since the side wall 4 a is a part of the main body container 1, the metal windows 30 a to 30 d are GND-connected through the GND connection member 50, the side wall 4 a and the ground wire 2. A connection form between the metal windows 30a to 30d and the side wall 4a (main body container 1) via the GND connection member 50 will be described in detail later.

  The support shelf 6 and the support beam 7 are made of a conductive material, for example, a nonmagnetic metal such as aluminum, and are electrically connected to the main body container 1. The insulator 28 is an electrical insulator, and for example, ceramic, quartz, polytetrafluoroethylene (PTFE), or the like is used. In the plasma processing apparatus 100, the support beam 7 also serves as a shower casing for supplying a processing gas, and the inside of the support beam 7 is against a surface to be processed of a substrate G to be processed (hereinafter referred to as “substrate G”). A gas flow path 8 extending in parallel is formed. In the gas flow path 8, a plurality of gas discharge holes 8 a for ejecting a processing gas into the processing chamber 5 are formed, and the gas flow path 8 is supplied from the processing gas supply mechanism 9 to the gas flow path 8 through the gas supply pipe 10. Processing gas is discharged into the processing chamber 5 from the gas discharge hole 8a. The processing gas can also be supplied from the metal windows 30a to 30d if the metal windows 30a to 30d are configured as a shower head.

  In the antenna chamber 4 formed on the upper side of the metal window 3, the high frequency antenna 11 is disposed so as to face the metal windows 30a to 30d. The high-frequency antenna 11 is disposed so as to be spaced apart from the metal windows 30a to 30d by a spacer 12 made of an insulating member. During the plasma processing, high-frequency power for forming an induction electric field is supplied to the high-frequency antenna 11 from the first high-frequency power source 13 through the matching unit 14 and the power supply member 15. The frequency of the high frequency power is, for example, 13.56 MHz. By supplying high-frequency power to the high-frequency antenna 11, eddy currents are induced in the metal windows 30 a to 30 d, and an induced electric field is formed in the plasma generation region in the processing chamber 5 by the eddy currents. Then, the processing gas supplied from the gas discharge holes 8 a is turned into plasma in the plasma generation region in the processing chamber 5 by the formed induction electric field. The relationship between induction of eddy currents in the metal windows 30a to 30d and plasma generation will be described later with reference to FIG.

  In the processing chamber 5, a mounting table 16 on which the substrate G is mounted so as to face the metal windows 30 a to 30 d is disposed in a state of being electrically insulated from the main body container 1 by the insulating member 17. The mounting table 16 is made of a conductive material, for example, aluminum, and its surface is anodized. The mounting table 16 is provided with an electrostatic chuck (not shown), and the substrate G is attracted and held on the mounting table 16 by the electrostatic chuck.

  A second high-frequency power source 18 is connected to the mounting table 16 via a matching unit 19 and a power supply line 20, and high-frequency power having a frequency of, for example, 3.2 MHz for bias is applied during the plasma processing. 16 is applied. Thereby, ions in plasma generated in the processing chamber 5 can be effectively drawn into the substrate G.

  Although not shown, a temperature control mechanism including a heating means such as a ceramic heater for controlling the temperature of the substrate G, a refrigerant flow path, and the like are provided inside the mounting table 16. Further, the support means for the substrate G is not limited to the mounting table 16, and when a bias high-frequency power supply or a temperature adjustment mechanism is not required, a pin or You may support by a rod-shaped member, or you may support by the pick of a conveyance mechanism, etc.

  A loading / unloading port 21 for loading / unloading the substrate G into / from the processing chamber 5 is provided on the side wall 5 a of the processing chamber 5, and the loading / unloading port 21 is opened and closed by a gate valve 22. An exhaust port 23 for exhausting the inside of the processing chamber 5 is provided in the bottom wall 5 b of the processing chamber 5, and an exhaust device 24 including a vacuum pump is connected to the exhaust port 23. The inside of the processing chamber 5 is exhausted by the exhaust device 24, and the pressure inside the processing chamber 5 is set and maintained at a predetermined vacuum atmosphere (for example, 1.33 Pa) while the plasma processing is being performed.

  Operation control of the plasma processing apparatus 100 is performed by a control unit 25 including a computer, and a user interface 26 and a storage unit 27 are connected to the control unit 25. The user interface 26 includes a keyboard on which a process manager manages command input for managing the plasma processing apparatus 100, a display for visualizing and displaying the operating status of the plasma processing apparatus 100, and the like. The storage unit 27 is configured to execute various processes executed by the plasma processing apparatus 100 under the control of the control unit 25 and to cause each part of the plasma processing apparatus 100 to execute processes (operations) according to the processing conditions. This program (process recipe) is stored. The control unit 25 calls a predetermined process recipe from the storage unit 27 in accordance with an instruction from the user interface 26 or the like, and executes a process according to the process recipe, thereby performing plasma processing.

  FIG. 3 is a schematic diagram for explaining the principle of plasma generation in the plasma processing apparatus 100. In FIG. 3A, the high-frequency antenna 11, the metal window 30a, and the plasma generation region are simply shown in a side view similar to FIG. 1, and FIG. An equivalent circuit corresponding to is shown. Here, it is assumed that the metal window 30a is in an electrically floating state.

In the plasma processing apparatus 100, when the high-frequency current I _RF flows through the high-frequency antenna 11, an eddy current I _LOOP is generated on the upper surface of the metal window 30a (the high-frequency antenna 11 side surface). Since the metal window 30 a is insulated from the support shelf 6, the support beam 7, and the main body container 1, the eddy current I _{LOOP that} has flowed to the upper surface of the metal window 30 a flows to the support shelf 6, the support beam 7, or the main body container 1. Instead, after flowing to one side surface of the metal window 30a, it flows to the lower surface (surface on the processing chamber 5 side) of the metal window 30a, and further flows to the other side surface of the metal window 30a and returns to the upper surface of the metal window 30a. In this way, an eddy current I _LOOP that loops from the upper surface to the lower surface of the metal window 30a is generated. An induced electric field E is formed in the plasma generation region in the processing chamber 5 by a current flowing in the lower surface of the metal window 30a in the eddy current I _LOOP . By forming the induction electric field E in the processing chamber 5 in this manner, the gas inside the processing chamber 5 is excited, and plasma is generated in the plasma generation region in the processing chamber 5.

In FIG. 3B, L _A and R _A are the inductance and resistance of the high-frequency antenna 11, respectively, and L _M1 and L _M2 are the inductance on the upper surface side and the inductance on the lower surface side of the metal window 30a, respectively. , I _P , L _P and R _P are the plasma current, inductance and resistance, respectively.

  FIG. 4 is a plan view showing first and second connection examples between the metal window and the GND connection member 50. Both of these first and second connection examples are common in that the GND connection member 50 is connected to one metal window at one ground point, and the shape of the metal window and / or The number is different. 4 (a) and 4 (b), the high-frequency antenna 11 is simplified and shown as a rectangle, but the high-frequency antenna 11 actually forms the circuit shown in FIG. 3 (b). For example, they are arranged in a spiral shape.

  In the first connection example shown in FIG. 4A, the metal window has four metal windows 30a to 30d having a square planar shape (the outer shape of the support shelf 6 is also square), and the metal windows 30a to 30d. A connection position of the GND connection member 50 (hereinafter referred to as “GND connection position”) is provided at a corner portion (near the intersection of two sides constituting the outer periphery) which is a central portion of each of the outer peripheral sides. The shapes of the metal windows 30a to 30d are appropriately changed to, for example, a rectangle according to the shape of the substrate G.

  FIG. 5 is a result of measuring an electron density distribution when plasma is generated with the metal windows 30a to 30d of FIG. 4A electrically floated (without connecting the GND connection member 50) (FIG. 5). And the result of measuring the electron density distribution when plasma is generated by connecting the GND connection member 50 to the corners of the metal windows 30a to 30d ("Metal window 1" in FIG. 5). It is a figure which compares and shows a point GND connection ").

Note that plasma generation conditions are such that the pressure of the processing chamber 5 is 20 mTorr, the source power is 5 kW, and the electron density of plasma generated using oxygen (O ₂ ) as a processing gas is measured. Further, the points A, O, and B on the horizontal axis in FIG. 5 correspond to the points A, O, and B indicated by black triangles (▲) in FIG.

  As is apparent from FIG. 5, even when the one-point GND connection is performed on each of the metal windows 30a to 30d by the GND connection member 50 (first connection example), the metal windows 30a to 30d are electrically floated. It can be seen that there is almost no decrease in the electron density of the plasma as compared with the case where the state is set, that is, the plasma can be induced with almost no change in the source efficiency. This is shown in an equivalent circuit as shown in FIG.

FIG. 6A is a diagram showing an equivalent circuit when plasma is generated with the metal window 30a of FIG. 4A being in an electrically floating state, and FIG. 6B is a diagram showing a GND in the metal window 30a. It is a figure which shows the equivalent circuit when the connection member 50 is connected and a plasma is generated. FIGS. 6A and 6B are both drawn in the same form as FIG. In FIG. 6, for the sake of convenience, the inductance on the upper surface side of the metal window 30a is divided into inductance components L _M1a and L _M1b in the middle of the two opposing side surfaces, and the inductance on the lower surface side of the metal window 30a is correspondingly divided. The two inductance components L _M2a and L _M2b are shown separately.

FIG. 6 (a) is substantially the same as FIG. 3 (b). The result of FIG. 5 shows that in FIG. 6, the one-point GND connection by the GND connection member 50 to the metal window 30a does not affect the eddy current looping from the upper surface side to the lower surface side of the metal window 30a. The size of the eddy current I _{LOOP (FLOAT)} that flows on the lower surface of the metal window 30a when the metal window 30a is in the float state, and the eddy current I _{LOOP (GND} that occurs when the metal window 30a is in a state of being connected to the GND at one point ₎ Is considered to be the same size.

  The metal window shown in the second connection example of FIG. 4B has the same metal windows 30a to 30d as the metal window 3 shown in FIG. A connection position (GND connection position) of the GND connection member 50 is provided. In FIG. 4B, the GND connection member 50 is not shown, and the GND connection position where the GND connection member 50 is connected in the metal windows 30a to 30d is indicated by black dots (●).

  FIG. 7 shows the distribution of potential (window potential) between point A and point B (between the ends on the outer peripheral side) indicated by black triangles (▲) set in the metal window 30b of FIG. It is a figure which shows typically about the case where 30b is made into an electrically floating state, and the case where the metal window 30b is one-point GND connected.

  When an eddy current flows between points A and B of the metal window 30b, a potential difference occurs due to the inductive reactance and capacitive reactance of the metal window 30b, and when the point A becomes a low potential, A potential gradient that becomes a high potential is generated, and becomes approximately 0 V at a low potential point. On the other hand, when one-point GND connection is performed at the approximate center between the points A and B of the metal window 30b, the same potential gradient is generated between the points A and B, but the GND connection position. As a result, the window potential is lowered as a whole so as to become the GND potential (0 V). Therefore, when the metal window 30b is connected at one point GND at the approximate center between the points A and B, the absolute value of the window potential of the metal window 30b is made smaller than when the metal window 30b is in a float state. Accordingly, it is possible to suppress the occurrence of spattering of the metal window 30b due to plasma.

  The effect of lowering the window potentials of the metal windows 30a to 30d in FIG. 4B as a whole can be obtained in the same manner with the metal windows 30a to 30d in FIG. The GND connection position for performing the one-point GND connection is preferably set at a position where the effect of lowering the window potential of the metal windows 30a to 30d can be obtained more remarkably. For example, it is preferable to set the GND connection position at the center portion between the point having the minimum potential and the point having the maximum potential in the metal window. In FIGS. 4 (a) and 4 (b), the GND connection position is set to the outer peripheral side of each metal window. This is the reason why it is provided in the vicinity of the center. On the other hand, for example, when the GND connection position is set at point A in FIG. 4B, the effect of lowering the window potential cannot be fully enjoyed.

  However, the GND connection position is actually affected by the arrangement of the high-frequency antenna 11. That is, it is required to provide a GND connection position in a region where the effect of lowering the window potential can be obtained in a region where the arrangement of the high frequency antenna 11 is not hindered. For example, the GND connection position may be provided near the center of the inner peripheral side of each metal window. As an example, in the case of FIG. 4B, the metal windows 30a to 30d face the GND connection position shown in the figure. A GND connection position can also be provided in the vicinity of the apex (near the center of the metal window).

  FIG. 8 is a plan view showing third and fourth connection examples between the metal window and the GND connection member 50. Here, the same metal windows 30a to 30d as those in FIGS. 2B and 4B are used. It is taken up. In the third and fourth connection examples, the GND connection member 50 is connected to the metal windows 30b and 30d arranged on the long side of the metal window 3 at two ground points (two-point GND connection). Although common in point, it is different in that the interval between the two GND connection positions is different. The GND connection member 50 is connected to the surface of the metal window 30b at the GND connection positions C and D in the third connection example, and is connected to the surface of the metal window 30b at the GND connection positions A and B in the fourth connection example. Yes.

FIGS. 9A and 9B are diagrams showing equivalent circuits corresponding to the third and fourth connection examples of FIGS. 8A and 8B for the metal window 30b, respectively. In FIG. 9, L _M1a1 is an inductance component between point A and point C, L _M1b1 is an inductance component between point D and point B, and L _M1c1 is an inductance component between point C and point _D. Inductance components L _M1a , L _M1b, etc. shown in FIG.

As shown in FIG. 9A, in the third connection example, a part of the eddy current I _LOOP generated on the upper surface of the metal window 30b flows to the circuit formed by the GND connection member 50. The eddy current I _LOOP circulating to the lower surface becomes smaller. As a result, the intensity of the induced electric field is weak, the plasma current I _P becomes small. In the fourth connection example, most of the eddy current I _LOOP generated on the upper surface of the metal window 30b flows to the circuit formed by the GND connection member 50, so that the eddy current I _LOOP circulating to the lower surface of the metal window 30b disappears. Or it becomes very small, and as a result, an induced electric field is not generated and plasma is not generated.

In this way, by adjusting the distance between the GND connection positions when performing the two-point GND connection, the magnitude of the eddy current I _LOOP that wraps around the lower surface of the metal window can be adjusted. Thus, the intensity distribution of the induced electric field can be improved or adjusted. That is, when the metal window 30b is electrically floated, two GND connection positions are provided in a portion where a relatively large eddy current I _LOOP flows on the upper surface of the metal window 30b. by reducing the magnitude of the eddy current I _LOOP sneaking from the side to the lower side, to weaken the strength of the corresponding induced electric field, it is possible to reduce the size of the thus plasma current I _P. In this way, it is possible to improve the uniformity of the plasma strength (uniformity of electron density) or adjust the plasma so as to generate a desired intensity distribution.

  In addition, when the two-point GND connection of the metal window is performed, the effect of lowering the window potential of the metal window can be obtained as in the case of the one-point GND connection of the metal window.

  FIG. 10 is a plan view showing a fifth connection example between the metal window and the GND connection member 50, and here, the same metal window as in FIG. 4C is taken up. FIG. 11 is a diagram illustrating an equivalent circuit corresponding to the fifth connection example. In the fifth connection example, the corners on the outer peripheral side of the metal windows 30e and 30f (the same reference numerals are assigned to equivalent metal windows) located at the corners of the metal window are connected by the variable capacitance capacitor 55, and the metal window By connecting 30e and 30f to the ceiling wall 4b of the antenna room 4, a current loop circuit is formed.

  Note that the metal windows (reference numerals omitted) other than the metal windows 30e and 30f are one-point GND connected by the GND connecting member 50 as in the first and second connection examples. Further, the electrical connection between the metal windows 30e and 30f for forming the current loop circuit including the variable capacitance capacitor 55 is not limited to the form using the ceiling wall 4b, and a member such as a copper plate or an aluminum plate is separately arranged. You may make it carry out using. The capacitance adjustment of the capacitance variable capacitor 55 may be directly performed manually by the process manager, or may be executed by the control unit 25 by inputting a setting command through the user interface 26.

  Empirically, eddy currents hardly flow at the corners of the metal windows 30e and 30f located at the corners of the metal window. For this reason, in the region corresponding to the corners of the metal windows 30e and 30f in the plasma generation region, The strength of the plasma is weakened. Therefore, by adjusting that the impedance Z of the current loop circuit is given by Z = ωL−1 / ωC (ω: angular frequency, L: inductance, C: conductance), the capacitance of the variable capacitance capacitor 55 is adjusted. The eddy current is increased by reducing the impedance Z, and the current flowing through the corners of the metal windows 30e and 30f is increased. Thereby, the plasma in the region corresponding to the corners of the metal windows 30e and 30f in the plasma generation region can be strengthened. In particular, when the impedance Z is negative and close to zero, a large eddy current flows through the variable capacitor 55 in the same direction as the high-frequency antenna 11, thus increasing the eddy current flowing on the lower surfaces of the corners of the metal windows 30 e and 30 f. Thus, a large induction electric field can be generated.

  In the fifth connection example, the current loop circuit is formed by connecting the variable capacitance capacitor 55 only to the metal windows 30e and 30f located at the corners of the metal window, but the same configuration is applied to other metal windows. Thus, the plasma intensity distribution can be adjusted.

  As described above, according to the embodiment of the present invention, it is possible to lower the window potential of the metal window while generating plasma without lowering the source efficiency by connecting the metal windows to one point GND. Further, it is possible to suppress spatter scraping of the metal window due to plasma. In addition, by connecting the two GND windows to the metal window and adjusting the distance of the GND connection position at that time, the magnitude of the eddy current flowing through the lower surface of the metal window is adjusted, and the plasma generation region corresponding to the GND connection position The plasma intensity at can be adjusted. Furthermore, by forming a current loop circuit connected between the corners of the metal window via a capacitor of a predetermined capacity, the eddy current flowing through the corner of the metal window is increased to cope with the corner of the metal window. It is possible to adjust the plasma intensity in the plasma generation region. By controlling the plasma intensity distribution in this way, it is possible to make the plasma processing on the substrate G uniform and to control the plasma processing more finely.

  FIG. 12 is a diagram showing the result of simulating the distribution of the electric field strength ratio on the length axis (straight line connecting points A, O, and B) shown in FIG. As shown in FIG. 12, it can be seen that in the one-point GND connection, there is almost no decrease in the electric field strength at the GND connection position (0 m). Comparing two-point GND connections (1/4 width, both ends), the GND connection position is longer at both ends, and the GND connection position is shorter than the 1/4 connection width when the GND connection position distance is short. It can be confirmed that the decrease in the electric field strength between the positions is remarkable. This is because the eddy current flowing on the lower surface side of the metal window 30s is reduced when the distance between the GND connection positions is long. Is shown.

  FIG. 13 is a diagram showing a result of simulating the distribution of the electric field strength ratio on the length axis (straight line connecting points O and B) shown in FIG. As shown in FIG. 13, by adjusting the capacitance of the variable capacitance capacitor 55, the electric field strength is increased in the vicinity of the length axis corresponding to the corners of the metal windows 30e and 30f as compared with the open case. I understand that. This indicates that eddy currents flowing on the lower surfaces of the metal windows 30e and 30f are increasing at the corners of the metal windows 30e and 30f.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to said embodiment. For example, in the above embodiment, the metal window is dropped to GND by connecting the metal window and the side wall 4a of the antenna chamber 4 via the GND connection member 50 made of a copper plate or the like. That is, although the low-resistance GND connection member 50 is used, the present invention is not limited to this. For example, a configuration may be adopted in which a metal window is dropped to GND through a certain resistance. In that case, as the GND connection member 50, a conductive member having a resistance higher than that of a copper plate, a member in which a resistance element is sandwiched between metal members such as a copper plate and an aluminum plate, and the like can be used.

  In the fifth connection example (FIG. 10) described above, the variable capacitance capacitor 55 is used. However, the present invention is not limited to this, and it is not necessary to change the distribution of the plasma intensity. May be used. The frequency of the high frequency power supplied to the high frequency antenna 11 is not limited to 13.56 MHz.

  In the plasma processing apparatus 100, the process recipe may be stored in a hard disk or a semiconductor memory, or is set in the storage unit 27 while being stored in a portable storage medium such as a CD-ROM or DVD. It may be. Furthermore, the process recipe may be appropriately transmitted from another apparatus via a dedicated line, for example.

DESCRIPTION OF SYMBOLS 1 Main body container 3 Metal window 4 Antenna room 4a Side wall 4a (antenna room) Ceiling wall 5 Processing room 11 High frequency antenna 28 Insulator 30a-30f, 30s-30v Metal window 50 GND connection member 55 Capacitance variable capacitor 100 Plasma processing equipment G Substrate

Claims (16)

A plasma processing apparatus for plasma processing a substrate,
A high-frequency antenna that generates inductively coupled plasma in the plasma generation region;
A metal window disposed between the plasma generation region and the high-frequency antenna and insulated from a main body container;
The metal window is composed of a plurality of metal windows insulated from each other by an insulator,
The plasma processing apparatus, wherein each of the plurality of metal windows is grounded at a single ground point.   2. The plasma processing apparatus according to claim 1, wherein the one grounding point is provided at a substantially center of an outer peripheral side or an inner peripheral side of each of the plurality of metal windows.   3. The plasma processing apparatus according to claim 1, wherein the one ground point is grounded via a resistor. An antenna chamber in which the high-frequency antenna is disposed and a processing chamber including the plasma generation region are provided with a container partitioned by a metal window including the plurality of metal windows,
The plasma processing apparatus according to claim 1, wherein the one grounding point is grounded by being connected to a side wall of the antenna chamber.   5. The at least one metal window of the plurality of metal windows is further connected to the ground at two grounding points by further being grounded at one grounding point. 6. The plasma processing apparatus of any one of Claims. The plurality of metal windows are arranged corresponding to the substrate having a rectangular shape,
6. The plasma processing apparatus according to claim 5, wherein the two grounding points are provided for a metal window provided at a position corresponding to a long side of the substrate among the plurality of metal windows.   7. The two grounding points are provided in regions where a relatively large amount of eddy current flows in each of the plurality of metal windows when the two grounding points are not provided. The plasma processing apparatus as described.   Two adjacent metal windows of the plurality of metal windows are connected via a capacitor, and the one grounding point provided in each of the two metal windows is electrically connected to form a current loop. The plasma processing apparatus according to claim 1, wherein a circuit is formed.   9. The plasma processing apparatus according to claim 8, wherein the capacitance of the capacitor is adjusted so that reactance of the current loop circuit is negative.   The said capacitor | condenser is connected to the position corresponding to the said corner | angular part of the metal window provided in the position corresponding to the corner | angular part of the said board | substrate among these metal windows. Plasma processing equipment. An antenna chamber in which the high-frequency antenna is disposed and a processing chamber including the plasma generation region are provided with a container partitioned by a metal window including the plurality of metal windows,
The plasma processing apparatus according to claim 8, wherein the one ground point is connected to a ceiling wall of the antenna room. The plasma generation region and the high-frequency antenna are isolated from each other by a metal window composed of a plurality of metal windows insulated from the main body container and insulated from each other by an insulator, and a high-frequency current is passed through the high-frequency antenna to thereby generate the plasma generation region. A plasma distribution adjustment method in a plasma processing apparatus for generating plasma by inductively coupled plasma to a substrate,
A plasma distribution adjusting method, wherein the plurality of metal windows are grounded at a single ground point.   13. The plasma distribution adjusting method according to claim 12, wherein at least one metal window of the plurality of metal windows is further grounded at one grounding point and grounded at two grounding points.   14. The plasma distribution adjusting method according to claim 13, wherein a current flowing between the two grounding points of the one metal window is adjusted by adjusting an interval between the two grounding points.   Two adjacent metal windows of the plurality of metal windows are connected via a capacitor, and a ground point provided on each of the two metal windows is electrically connected to form a current loop circuit. The plasma distribution adjustment method according to claim 12, wherein:   16. The plasma distribution adjustment method according to claim 15, wherein the capacitance of the capacitor is adjusted so that the reactance of the current loop circuit is negative.

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