JP2016096342A - Plasma processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma processing device having upper and lower electrodes, which is arranged so as to prevent the occurrence of discharge when applying a DC voltage to the upper electrode.SOLUTION: A plasma processing device arranged so as to process, by plasma, an object to be processed by applying a high frequency power between an upper electrode 42 and a lower electrode comprises: a ground member 61 provided over the upper electrode 42 through insulating members 60; an electrode support body 52 supporting the upper electrode 42; and a DC power source 81 operable to apply a DC voltage to the upper electrode 42. In the upper electrode 42, gas diffusion rooms 54, 55 communicating to gas supply ports 53 provided in a lower surface of the upper electrode 42 are provided. In the insulating members 60, gas passages 62 are formed, communicating to the gas diffusion rooms 54, 55. In each gas passage 62, a bent part 63 is provided so that one end of the gas passage 62 cannot be visually recognized from the other end in plan view, and the bent part serves to flow gas in a direction where the gas has at least a horizontal component.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a plasma processing apparatus for performing plasma processing on an object to be processed.

  As a device for performing fine processing such as etching or film formation on a target object such as a semiconductor wafer (hereinafter referred to as “wafer”) by the action of plasma, for example, a parallel plate type (capacitive coupling type) plasma processing device, induction Coupled plasma processing apparatuses, microwave plasma processing apparatuses, and the like have been put into practical use.

  Among these, in the parallel plate type plasma processing apparatus, high-frequency power is applied to at least one of the upper electrode and the lower electrode provided to face each other, and gas is excited by the electric field energy to generate plasma. The object to be processed is finely processed by the discharge plasma. Such a parallel plate type plasma processing apparatus is mainly used when performing an etching process, for example.

  In such a parallel plate type plasma processing apparatus, a processing gas is introduced into a processing vessel provided with an upper electrode and a lower electrode, and high-frequency power is applied to at least one of the electrodes to generate a processing gas plasma. Thus, for example, an etching process is performed on the wafer.

  By the way, in forming an etching hole by an etching process, a photoresist is used as an etching mask. However, the photoresist is negatively charged, and in the initial stage of etching, the charge is neutralized on the etching surface. However, as the etching progresses and the aspect ratio increases, positive ions are deposited at the bottom of the etching hole, and the etching surface is charged with a positive charge. There was a problem that the etching was bent due to the repulsion of the charge, and the shape of the etching hole was bent or distorted. In addition, since positive ions hardly reach the bottom of the etching hole, there is a problem that the etching rate is lowered.

  Therefore, in order to solve such problems, the application of high-frequency power to the electrodes is alternately turned on and off alternately, plasma generation and extinction in the processing container are repeated, plasma processing is performed, and high-frequency power is turned on. For example, Patent Document 1 proposes a method of applying a negative DC voltage to the upper electrode so that the applied voltage is higher in the period in which the high-frequency power is turned off than the period in which the power is applied.

  According to such a method, by applying a negative DC voltage while the high-frequency power source is turned off, more secondary electrons are generated and accelerated greatly to enter the etching hole. Therefore, many secondary electrons and negative ions can be supplied into the contact hole while the high frequency power supply is turned off. As a result, it is possible to neutralize the charge in the contact hole that has been charged to a positive charge, so that when the plasma is generated by turning on the high frequency power supply, positive ions are not bent in the etching hole, Good etching can be performed.

JP 2010-219491 A

  By the way, in recent years, miniaturization of semiconductor devices has progressed, and it is required to form etching holes with a high aspect ratio. In order to form such high aspect ratio etching holes, it is necessary to increase the negative DC voltage applied during the period when the high-frequency power source is turned off in order to accelerate the secondary electrons and ions more greatly. .

  However, when the negative DC voltage is increased, abnormal discharge occurs in the vicinity of the upper electrode, and the reaction product generated by the discharge falls on the upper surface of the wafer, causing a decrease in the yield of semiconductor device products. The problem that occurred. This abnormal discharge will be described.

  FIG. 9 is a longitudinal sectional view showing an outline of the configuration in the vicinity of the upper electrode of the plasma processing apparatus that performs the above-described etching process. As shown in FIG. 9, the upper electrode 200 includes an electrode plate 201 provided to face the wafer, and an electrode support 202 that supports the electrode plate 201. The electrode plate 201 is made of a semiconductor such as silicon, and the electrode support 202 is made of a conductor such as aluminum. Above the electrode support 202, a grounding member 204 formed of a conductor is provided in parallel with the electrode support 202 via a cylindrical insulating member 203. A gas diffusion chamber 211 that communicates with a gas supply port 210 formed in the electrode plate 201 is provided inside the electrode support 202, and the gas diffusion chamber 211 is formed inside the insulating member 203. Process gas is supplied through the gas flow passage 212. A DC power supply 220 is electrically connected to the upper electrode 200 and the ground member 204 so that the upper electrode 200 side is a negative electrode and the ground member 204 side is a positive electrode.

  In such a plasma processing apparatus, conventionally, a negative DC voltage of about 300 V, for example, is applied to the upper electrode 200. In that case, although no problem occurs, in order to further accelerate the secondary electrons and ions, if the negative DC voltage to be applied is increased to, for example, about 1200 V, the electrode support that constitutes the upper electrode 200 that is the negative electrode It has been confirmed by the present inventors that a discharge is generated via the flow passage 212 between the 202 and the grounding member 204 which is a positive electrode. Therefore, even when a higher DC voltage than that in the past is applied, measures are required to prevent discharge.

  The present invention has been made in view of such a point, and in a plasma processing apparatus having an upper electrode and a lower electrode, it is intended to prevent discharge from being generated when a higher DC voltage than that of the prior art is applied to the upper electrode. It is aimed.

  In order to achieve the above object, the present invention provides a plasma for applying a high-frequency power between an upper electrode and a lower electrode provided in a processing vessel to convert a processing gas into plasma, and subjecting the object to plasma processing with the plasma. A processing apparatus, a grounding member provided above the upper electrode through an insulating member, an electrode support that supports the upper electrode, a DC power source that applies a negative DC voltage to the upper electrode, A gas diffusion chamber communicating with a gas supply port provided on a lower surface of the upper electrode is provided inside the upper electrode, and a gas flow communicating with the gas diffusion chamber is provided inside the insulating member. A direction is formed in the gas flow passage so that the gas flowing in the gas flow passage has at least a horizontal component so that the other end cannot be seen from one end of the gas flow passage in a plan view. Shed A bent portion is provided, and a bent portion of the gas flow passage is provided in an insulating member interposed between the grounding member and the electrode support from the end of the grounding member toward the end of the electrode support. The passage length is formed by the relationship between the pressure in the gas diffusion chamber and the DC voltage to be applied.

  The voltage at which discharge occurs between parallel electrodes is determined by the product of the distance between the electrodes and the gas pressure between the electrodes according to Paschen's law. The inventors increase the voltage at which discharge occurs if the distance between the electrodes, that is, the length of the gas flow path, can be increased. In other words, the discharge is not generated even when a high voltage is applied. We focused on the points that can be prevented. The present invention is based on this idea, and according to the present invention, a gas flow passage formed in an insulating member interposed between the upper electrode and the ground member is connected to one of the gas flow passages in a plan view. Since the bent portion is provided so that the gas flowing in the gas flow passage flows in a direction having at least a horizontal component so that the other end portion cannot be visually recognized from the end portion of the upper electrode and the ground member, The distance of the gas flow passage can be made longer than the case where the gas flow passage is formed linearly between the two. As a result, the distance between the electrodes, which is the determinant of the discharge voltage, and the gas pressure between the electrodes can be substantially increased, thereby suppressing the occurrence of discharge due to the application of the DC voltage. can do.

  In addition, since the distance of the gas flow passage is increased, the pressure loss of the processing gas in the gas flow passage is also increased. As a result, the gas pressure between the electrodes increases, and this can also suppress the occurrence of discharge due to the application of the DC voltage.

  Furthermore, since the bent portion functions as an obstacle by forming the bent portion so that the other end portion cannot be seen from one end portion of the gas flow passage in a plan view, Thus, no discharge is generated linearly between the upper electrode and the ground member. Therefore, also from this point, the occurrence of discharge due to the application of the DC voltage can be suppressed.

  Between the gas supply port and the gas diffusion chamber, there may be provided a resistance portion that increases the pipe resistance between the gas supply port and the gas diffusion chamber.

  The upper electrode is constituted by an electrode plate facing the object to be processed and an electrode support provided on the upper surface of the electrode plate, and the resistance portion may be provided on the electrode support. It may be provided on the plate side.

  According to the present invention, in a plasma processing apparatus including an upper electrode and a lower electrode, it is possible to prevent discharge from occurring when a DC voltage is applied to the upper electrode.

It is a schematic longitudinal cross-sectional view which shows an example of a structure of the plasma processing apparatus which implements this invention. It is a longitudinal cross-sectional view which shows the outline of a structure of the upper electrode vicinity concerning this Embodiment. It is a timing chart which shows the operation state of each power supply at the time of plasma processing. It is a longitudinal cross-sectional view which shows the outline of the structure of the upper electrode vicinity concerning other embodiment. It is a longitudinal cross-sectional view which shows the outline of the structure of the upper electrode vicinity concerning other embodiment. It is a longitudinal cross-sectional view which shows the outline of the structure of the upper electrode vicinity concerning other embodiment. It is explanatory drawing which shows the state which provided the resistance part in the upper electrode. It is explanatory drawing which shows the state which provided the resistance part in the upper electrode. It is a longitudinal cross-sectional view which shows the outline of the structure of the conventional upper electrode vicinity.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view showing a schematic configuration of a plasma processing apparatus 1 according to an embodiment of the present invention. The plasma processing apparatus 1 according to the present embodiment is, for example, a parallel plate type plasma etching processing apparatus.

  The plasma processing apparatus 1 includes a substantially cylindrical processing container 11 provided with a wafer chuck 10 that holds a wafer W that is a silicon substrate. The processing container 11 is electrically connected to the ground line 12 and grounded. An electrode (not shown) is provided inside the wafer chuck 10 so that the wafer W can be adsorbed and held by an electrostatic force generated by applying a DC voltage to the electrode.

  The lower surface of the wafer chuck 10 is supported by a susceptor 13 serving as a lower electrode. The susceptor 13 is formed in a substantially disk shape from a metal such as aluminum. A support base 15 is provided at the bottom of the processing container 10 via an insulating plate 14, and the susceptor 13 is supported on the upper surface of the support base 15.

  A conductive correction ring 20 made of, for example, silicon is provided on the upper surface of the susceptor 13 and on the outer peripheral portion of the wafer chuck 10 to improve the uniformity of plasma processing. The outer surface of the susceptor 13, the support base 15, and the correction ring 20 is covered with a cylindrical member 21 made of, for example, quartz.

  A coolant path 15a through which a coolant flows is provided in the support base 15 in, for example, an annular shape. By controlling the temperature of the coolant supplied by the coolant path 15a, the wafer W held by the wafer chuck 10 is controlled. The temperature can be controlled. Further, a heat transfer gas pipe 22 for supplying, for example, helium gas as a heat transfer gas between the wafer chuck 10 and the wafer W held by the wafer chuck 10, for example, connects the susceptor 13, the support base 15, and the insulating plate 14. It is provided through.

  The susceptor 13 is electrically connected via a first matching unit 31 to a first high frequency power supply 30 for supplying high frequency power to the susceptor 13 to generate plasma. The first high frequency power supply 30 is configured to output a high frequency power of 27 to 100 MHz, for example, 40 MHz in the present embodiment, for example. The first matching unit 31 matches the internal impedance of the first high-frequency power source 30 and the load impedance, and when the plasma is generated in the processing container 11, the internal impedance of the first high-frequency power source 30. And the load impedance appear to coincide with each other.

  The susceptor 13 is provided with a second high-frequency power supply 40 for supplying ions to the wafer W by supplying a high-frequency power to the susceptor 13 and applying a bias to the wafer W via a second matching unit 41. Are electrically connected. The second high frequency power supply 40 is configured to output a high frequency power of 400 kHz to 13.56 MHz, for example, 3.2 MHz in the present embodiment, for example. Similar to the first matching device 41, the second matching device 41 matches the internal impedance of the second high-frequency power source 40 with the load impedance.

  Above the susceptor 13, which is the lower electrode, an upper electrode 42 is provided in parallel to face the susceptor 13. The upper electrode 42 is supported on the upper portion of the processing container 11 via an insulating shielding member 50. The upper electrode 42 includes an electrode plate 51 that forms a surface facing the wafer W held by the wafer chuck 10, and an electrode support 52 that supports the electrode plate 51 from above. In the electrode plate 51, a plurality of gas supply ports 53 for supplying a processing gas into the processing container 11 are formed so as to penetrate the electrode plate 51. The electrode plate 51 is made of, for example, a low-resistance conductor or semiconductor with low Joule heat, and silicon, for example, is used in the present embodiment. Moreover, the electrode support body 52 is comprised with the conductor, and aluminum is used in this Embodiment, for example.

  A DC power supply 81 is electrically connected to the upper electrode 42 through a low-pass filter 80 that traps high frequencies from the first high frequency power supply 30 and the second high frequency power supply 40. The DC power supply 81 is connected such that the upper electrode 42 side is a negative electrode and the ground member 61 side is a positive electrode. Thereby, a negative DC voltage can be applied to the upper electrode 42. In the present embodiment, the negative DC voltage is 1200V.

  The first high-frequency power source 30, the first matching unit 31, the second high-frequency power source 40, the second matching unit 41, and the DC power source 81 are connected to the control unit 100, which will be described later. 100.

  A gas diffusion chamber 54 formed in a substantially disk shape is provided in the center portion inside the electrode support 52. A gas diffusion chamber 55 formed in an annular shape is further provided outside the gas diffusion chamber 54. A plurality of gas holes 56 extending downward from the gas diffusion chambers 54 and 55 are formed in the lower part of the electrode support 52, and the gas supply port 53 is connected to the gas diffusion chambers 54 and 55 through the gas holes 56. ing. The gas diffusion chamber 54 and the gas diffusion chamber 55 are provided separately by adjusting the internal pressures of the gas diffusion chamber 54 and the gas diffusion chamber 55, respectively, and the gas hole 56 near the center of the electrode support 52 and the vicinity of the outer periphery. This is because the flow rate of the processing gas flowing from the gas holes 56 is adjusted independently, and the arrangement and shape of the gas diffusion chambers 54 and 55 are not limited to the present embodiment.

  Above the electrode support 52, a substantially disk-shaped grounding member 61 is provided in parallel to face the electrode support 52 via an approximately cylindrical insulating member 60. The ground member 61 is made of a conductor, and for example, aluminum is used in the present embodiment.

  As shown in FIG. 2, a gas flow passage 62 communicating with the gas diffusion chambers 54 and 55 is formed inside the insulating member 60. The gas flow passage 62 has a gas flowing in the gas flow passage 62 so that the end portion on the electrode support 52 side cannot be seen through the gas flow passage 62 from the end portion on the grounding member 61 side in a plan view. Is provided with a bent portion 63 that flows in a direction having at least a horizontal component. For example, as shown in FIG. 2, the bent portion 63 in the present embodiment is formed so that gas flows spirally from the end on the grounding member 61 side toward the end on the electrode support 52 side. In addition, the direction having a horizontal component means that all directions other than the vertical direction, such as diagonally upward and diagonally downward, are included in addition to the horizontal direction.

  By providing the bent portion 63 in the gas flow passage 62, the distance of the gas flow passage 62 can be made longer than in the case where the gas flow passage 212 is provided linearly as in the conventional insulating member 203 shown in FIG. it can. The bent portion 63 in the present embodiment is configured such that the distance of the gas flow passage 62 is about three times that of the gas flow passage 212 of the conventional insulating member 203. The bent portion 63 makes the distance between the electrodes, ie, the gas flow path 62 between the ground member 61 and the upper electrode 42 out of the distance between the electrodes and the gas pressure between the electrodes, which is a determinant of the discharge voltage. Therefore, it acts to suppress the occurrence of discharge due to the application of a DC voltage. The length of the gas flow passage 62 is arbitrarily set within a range where no discharge occurs based on the relationship between the pressure in the gas diffusion chambers 54 and 55 and the applied DC voltage. However, the present invention is not limited to this embodiment.

  Further, by providing the bent portion 63, the other end portion cannot be visually recognized from one end portion of the gas flow passage 62 in a plan view, so that the bent portion 63 is formed between the upper electrode 42 and the ground member 61. It functions as an obstacle that prevents the discharge from occurring linearly between them. Therefore, it is possible to more reliably suppress the occurrence of discharge due to the application of the DC voltage.

In the grounding member 61, a gas introduction port 70 is formed through the grounding member 61 at a position corresponding to the gas flow path 62. A gas supply pipe 71 is connected to the gas inlet 70. A processing gas supply source 72 is connected to the gas supply pipe 71 as shown in FIG. 1, and the processing gas supplied from the processing gas supply source 72 is gas through the gas supply pipe 71 and the gas flow passage 62. It is supplied to the diffusion chambers 54 and 55. Then, the processing gas supplied to the gas diffusion chambers 54 and 55 is introduced into the processing container 11 through the gas hole 56 and the gas supply port 53. That is, the upper electrode 42 functions as a shower head that supplies a processing gas into the processing container 11. As the processing gas, various gases used in conventional plasma etching can be employed. For example, a fluorocarbon gas such as C ₄ F ₈ may be used, and other gases such as Ar and O ₂ may be used. Gas may be included.

  The gas supply pipe 71 is provided with a flow rate adjusting mechanism 73, and the amount of gas supplied from the processing gas supply source 72 to the gas diffusion chambers 54 and 55 can be controlled. The flow rate adjusting mechanism 73 is configured by, for example, a mass flow controller and a valve.

  An exhaust port 90 is provided on the bottom surface of the processing container 11. An exhaust device 92 is connected to the exhaust port 90 via an exhaust pipe 91. By driving the exhaust device 92, the atmosphere in the processing container 11 can be decompressed to a predetermined degree of vacuum. In addition, the inner wall of the processing vessel 11 is covered with a liner 93 having a sprayed coating made of a plasma-resistant material formed on the surface.

  The plasma processing apparatus 1 is provided with the control unit 100 as described above. The control unit 100 is, for example, a computer and has a program storage unit (not shown). The program storage unit also stores a program for operating the plasma processing apparatus 1 by controlling the power supplies 30, 40, 81, the matching units 31, 41, the flow rate adjusting mechanism 73, and the like.

  For example, this program can control the on / off and output of the first high-frequency power supply 30. Therefore, for example, the first high-frequency power supply 30 is continuously turned on to generate plasma continuously, or alternately turned on and off to apply high-frequency power in a pulsed manner and the plasma exists. It is possible to alternately form a state in which is disappeared. Also, the second high frequency power supply 40 for bias can be controlled to be turned on, off, and output similarly to the first high frequency power supply 30, and a bias can be applied continuously during the plasma processing, It is possible to apply a bias in a pulsed manner in synchronization with on / off of the high-frequency power supply 30. Further, the DC power supply 81 can be turned on / off and the voltage and current can be controlled.

  In the present embodiment, for example, as shown in FIG. 3, the first high frequency power supply 30 is alternately turned on and off, and the second high frequency power supply 40 is alternately turned on and off in synchronization therewith. The state where the plasma is generated and the state where the plasma disappears are alternately repeated. At the same time, a negative DC voltage is applied from the DC power supply 81 to the upper electrode 42 in synchronization with the on / off of the first high frequency power supply 30. At this time, the DC power supply 81 is controlled such that the absolute value of the negative DC voltage applied is larger during the period in which the plasma is extinguished than during the period in which the plasma is generated.

  By controlling the power sources 30, 40, 81 in this way, the plasma sheath of the plasma generated by the first high frequency power source 30 and the second high frequency power source 40 are generated during the power source 30, 40 on period. A thick plasma sheath is formed. As a result, the electrons are reflected by the plasma sheath while the power sources 30 and 40 are on, but the plasma sheath disappears and the secondary electrons easily reach the wafer W when the power sources 30 and 40 are off.

  During this time, the absolute value of the negative DC voltage applied by the DC power supply 81 is applied so that the period in which the plasma is extinguished is larger than the period in which the plasma is generated, thereby the power source 30, A large amount of electrons can be supplied to the surface of the wafer W during the 40-off period. Therefore, it is possible to neutralize the charge in the contact hole charged with positive charge, so that positive ions will not bend in the etching hole when the high frequency power supply is turned on and plasma is generated. Etching can be performed.

  The above program is recorded on a computer-readable storage medium H such as a computer-readable hard disk (HD), a flexible disk (FD), a compact disk (CD), a magnetic optical desk (MO), or a memory card. May have been installed in the control unit 100 from the storage medium H.

  The plasma processing apparatus 1 according to the present embodiment is configured as described above. Next, the plasma etching process in the plasma processing apparatus 1 according to the present embodiment will be described.

  In the plasma etching process, first, the wafer W is loaded into the processing container 11 and is placed and held on the wafer chuck 10. Next, the inside of the processing container 11 is exhausted by the exhaust device 92, and at the same time, the processing gas is supplied from the processing gas supply source 72 into the processing container 11 at a predetermined flow rate. At this time, the flow rate of the processing gas is adjusted by the flow rate adjusting mechanism 73 so that the pressure in the processing container 11 falls within a range of, for example, 10 to 150 Pa.

  Thereafter, high frequency power is continuously applied to the susceptor 13 as the lower electrode by the first high frequency power supply 30 and the second high frequency power supply 40, and a DC voltage is continuously applied to the upper electrode 42 by the DC power supply 81. Apply. Thereby, the processing gas supplied into the processing container 11 is turned into plasma between the upper electrode 42 and the susceptor 13.

  Thereafter, the power supplies 30, 40, and 81 are controlled by the pattern shown in FIG.

  At this time, since the gas flow passage 62 is provided with the bent portion 63, the discharge caused by the application of the DC voltage does not occur between the ground member 61 and the upper electrode 42, and the reaction generated by the discharge. A decrease in the yield of the semiconductor device product due to the product falling on the wafer can be avoided. As a result, it is possible to apply a high negative DC voltage, so that it is possible to form an etching hole having a higher aspect ratio than in the prior art.

  According to the above embodiment, the gas flowing through the gas flow passage 62 has at least a horizontal component in the gas flow passage 62 formed in the insulating member 60 interposed between the upper electrode 42 and the ground member 61. Since the bent portion 63 is provided so as to flow in the direction in which the other end portion cannot be seen from the end portion of the gas flow passage 62 in plan view, the upper electrode and the grounding member are conventionally provided. The distance of the gas flow passage can be made longer than the case where the gas flow passage is formed linearly between the two. Accordingly, the distance between the electrodes, that is, the electrical distance between the upper electrode 42 and the ground member 61 among the distance between the electrodes and the gas pressure between the electrodes, which is a determinant of the discharge voltage, is determined. It can be made substantially longer without being physically moved with the grounding member 61. Therefore, even when a DC voltage is applied at a higher voltage than before by the DC power supply 81, the occurrence of discharge due to the application of the DC voltage can be suppressed.

  Further, as the distance of the gas flow passage 62 becomes longer, as a result, the pressure loss of the processing gas in the gas flow passage 62 also increases. Therefore, the pressure difference at both ends of the gas flow passage 62 increases. In other words, when the processing gas is supplied from the processing gas supply source 72, the pressure of the processing gas on the ground member 61 side increases. Therefore, it is possible to suppress the occurrence of discharge due to the application of the DC voltage.

  Furthermore, the bent portion 63 is formed so that the other end portion cannot be seen from the end portion of the gas flow passage 62 in a plan view, so that the bent portion 63 is formed between the upper electrode 42 and the ground member 61. It functions as an obstacle that prevents the discharge from occurring linearly between them. Therefore, according to the above embodiment, generation | occurrence | production suppression resulting from the application of DC voltage can be performed more reliably.

  In the above embodiment, the bent portion 63 of the gas flow passage 62 is formed in a spiral shape, but the shape of the gas flow passage 62 is not limited to this embodiment, and the bent portion 63 If it is formed so that the other end portion cannot be viewed from one end portion of the gas flow passage 62 in a plan view, various shapes can be obtained. Specifically, for example, as shown in FIG. 4, the longitudinal cross-sectional shape of the bent portion 63 may be substantially U-shaped, or may be substantially V-shaped as shown in FIG. 5.

  Further, as shown in FIG. 6, for example, the processing gas is introduced into the gas flow passage so that the end on the electrode support 52 side cannot be visually recognized from the end on the grounding member 61 side through the gas flow passage 62. The straightening member 110 may be provided inside the gas flow passage 62 so as to prevent the straight movement in the 62, and the bent portion 63 may be formed corresponding to the outer shape of the straightening member 110. Further, the rectifying member 110 is connected to, for example, a driving mechanism (not shown) so as to be movable, and the vertical and horizontal positions of the rectifying member 110 in the gas flow passage 62 are changed to change the gas flow passage 62. The pressure loss may be adjusted according to the situation. In such a case, the flow regulating member 110 may be formed into a preferable shape by pressure adjustment, such as a valve body of a needle valve. In any case, it is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the scope of claims. It is understood that it belongs to the technical scope of the present invention.

  In the above embodiment, the bent portion 63 is provided in the gas flow passage 62 so that the electrical distance between the upper electrode 42 and the ground member 61 is increased. The gas pressure between the electrodes, which is a determinant of the above, has also increased. However, in order to positively increase the gas pressure between the electrodes, for example, the resistor 120 that increases the pressure loss of the processing gas on the gas diffusion chambers 54 and 55 side May be provided.

  Specifically, for example, as shown in FIG. 7, a part of the gas hole 56 of the electrode support 52 is formed into an orifice shape, that is, an annular projecting portion that projects toward the center of the gas hole 56 is provided. Thus, the resistance portion 120 may be formed. For example, as shown in FIG. 8, a part of the gas supply port 53 of the electrode plate 51 may be formed in an orifice shape to form the resistance portion 120. Moreover, the resistance part 120 may be provided in both the gas hole 56 and the gas supply port 53, and the resistance part 120 can be provided if the pipe line resistance between the gas diffusion chambers 54 and 55 and the gas supply port 53 can be increased. The shape and arrangement can be arbitrarily set. Therefore, it can be said that the resistance portion 120 is formed even when the diameter of the gas hole 56 is made small over the entire gas hole 56, for example, instead of providing a protruding portion at a part of the gas hole 56. In any case, the differential pressure before and after the resistance portion 120 increases, and thereby the pressure in the gas diffusion chambers 54 and 55 with respect to the pressure in the processing container 11 increases. As a result, the pressure of the processing gas in the gas flow passage 62 on the upstream side of the gas diffusion chambers 54 and 55 is also increased, thereby suppressing the occurrence of discharge due to the application of a DC voltage.

  In particular, since the diameter of the gas supply port 53 of the electrode plate 51 gradually increases as it is exposed to the plasma in the processing vessel 11 and is eroded, the pipe resistance of the gas supply port 53 itself decreases with time. End up. In this case, the pressure of the processing gas in the gas diffusion chambers 54 and 55 is lowered, and as a result, the pressure in the gas flow passage 62 is also lowered and discharge is likely to occur. Therefore, in the past, it was necessary to periodically replace the electrode plate 51. However, as in the present embodiment, the resistance portion 120 is provided to ensure pressure loss and maintain the pressure in the gas diffusion chambers 54 and 55. By doing so, it is possible to suppress a decrease in gas pressure over time. Thereby, the exchange frequency of the electrode plate 51 can also be suppressed low. As described above, since the gas supply port 53 of the electrode plate 51 is exposed to the plasma in the processing container 11 and is eroded, the resistance portion 120 is separated from the lower end surface of the electrode plate 51 by a predetermined distance or more. It is preferable to provide it at a position.

  As mentioned above, although preferred embodiment of this invention was described, this invention is not limited to this example. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to.

DESCRIPTION OF SYMBOLS 1 Plasma processing apparatus 2 Microwave supply part 10 Wafer chuck 11 Processing container 12 Ground wire 13 Susceptor 14 Insulating plate 15 Support stand 20 Compensation ring 21 Cylindrical member 22 Heat-transfer gas pipe 30 1st high frequency power supply 31 1st matching device 40 Second high frequency power source 41 Second matching unit 42 Upper electrode 50 Shield member 51 Electrode plate 52 Electrode support 53 Gas supply port 54, 55 Gas diffusion chamber 56 Gas hole 60 Insulating member 61 Grounding member 62 Gas flow path 70 Gas introduction Port 71 Gas supply pipe 72 Processing gas supply source 73 Flow rate adjusting mechanism 80 Low-pass filter 81 DC power supply 90 Exhaust port 91 Exhaust pipe 92 Exhaust device 93 Liner 100 Control unit 110 Rectifying member 120 Resistance unit W Wafer

Claims (3)

A plasma processing apparatus for applying a high frequency power between an upper electrode and a lower electrode provided in a processing container to convert a processing gas into plasma, and subjecting the target object to plasma processing with the plasma,
A grounding member provided above the upper electrode via an insulating member;
An electrode support for supporting the upper electrode;
A DC power supply for applying a negative DC voltage to the upper electrode,
Inside the upper electrode, a gas diffusion chamber communicating with a gas supply port provided on the lower surface of the upper electrode is provided,
A gas flow path communicating with the gas diffusion chamber is formed inside the insulating member,
The gas flow passage has a bent portion for flowing a gas flowing in the gas flow passage in a direction having at least a horizontal component so that the other end cannot be visually recognized from one end of the gas flow passage in a plan view. Provided,
The bent portion of the gas flow passage is formed in an insulating member interposed between the grounding member and the electrode support from the end of the grounding member toward the end of the electrode support, and the length of the passage The plasma processing apparatus is set according to a relationship between a pressure in the gas diffusion chamber and a DC voltage to be applied. The resistance part which increases the pipe line resistance between the said gas supply port and a gas diffusion chamber is provided between the said gas supply port and the said gas diffusion chamber, The Claim 1 characterized by the above-mentioned. Plasma processing equipment. The upper electrode includes an electrode plate facing the object to be processed and an electrode support provided on the upper surface of the electrode plate, and the resistance portion is provided on the electrode support. The plasma processing apparatus according to claim 2.

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