JP7394694B2 - plasma processing equipment - Google Patents

Description

The present disclosure relates to a plasma processing apparatus.

For example, Patent Document 1 proposes removing by-products formed by etching by including a bias power supply section that applies a pulse-modulated DC voltage to a support structure as a bias voltage for ion attraction. do.

JP2016-82020A

The present disclosure provides a plasma processing apparatus that efficiently etches a substrate while suppressing by-products formed by etching from adhering to a window for introducing high frequency waves.

According to one aspect of the present disclosure, there is provided a plasma processing apparatus that performs plasma processing on a substrate, including a plasma generation unit that generates plasma in a processing container, and a mounting surface that is inclined in the processing container. a support structure on which a substrate is placed and rotatably supports the substrate; a first slit plate made of quartz provided between the plasma generation section and the support structure and having a first slit formed therein; a second slit plate made of quartz that is provided between the plasma generation unit and the support structure under the first slit plate and has a second slit formed therein, the first slit comprising: A plasma processing apparatus is provided in which the second slit is offset from the adjacent second slit in a direction opposite to the inclination direction of the mounting surface.

According to one aspect, while efficiently etching the substrate, it is possible to suppress by-products formed by etching from adhering to the high frequency introduction window.

FIG. 1 is a cross-sectional view schematically showing an example of a tilt pre-clean device according to an embodiment. FIG. 3 is a diagram showing an example of an internal structure of a container section according to an embodiment. FIG. 2 is a diagram for explaining a support structure according to an embodiment. AA sectional view of FIG. 1. FIG. 3 is a diagram illustrating an example of a structure for holding a shield plate according to an embodiment. The figure which showed an example of the position of the slit of the slit plate based on one embodiment. FIG. 3 is a diagram for explaining the position of a slit and the movement of ions and deposits according to one embodiment. FIG. 3 is a diagram illustrating an example of a simulation for optimizing the position of a slit according to an embodiment. The figure which shows an example of the simulation result for optimizing the masking of the slit based on the modification of one embodiment.

Hereinafter, embodiments for implementing the present disclosure will be described with reference to the drawings. In each drawing, the same components are given the same reference numerals, and redundant explanations may be omitted.

[Tilt pre-clean device]
First, a tilt pre-clean device 10 according to an embodiment will be described with reference to FIGS. 1 to 5. FIG. 1 is a cross-sectional view schematically showing an example of a tilt pre-clean device 10 according to an embodiment. FIG. 2 is a diagram showing an example of the internal structure of the container section 40 according to one embodiment. FIG. 3 is a diagram for explaining the support structure 11 according to one embodiment. FIG. 4 is a sectional view taken along line AA in FIG. FIG. 5 is a diagram showing an example of a structure for gripping the shield plate 13 according to an embodiment.

1 and 3 show the tilt pre-clean device 10 in which the processing container 12 is cut in one plane including the axis PX extending in the vertical direction. The tilt pre-clean device 10 is an example of a plasma processing device that performs plasma processing on a substrate W. Note that FIG. 1 shows the tilt pre-clean device 10 with the support structure 11 not tilted, and FIG. 3 shows the tilt pre-clean device 10 with the support structure 11 tilted. The support structure 11 places the substrate W on an inclined mounting surface 11a within the processing container 12, and rotatably supports the substrate.

The tilt pre-clean device 10 includes a support structure 11, a processing container 12, a gas supply section 14, an ICP source unit 16, an exhaust system 20, a bias power supply section 62, and a control section Cnt. The processing container 12 has a substantially cylindrical shape and is made of aluminum. In one embodiment, the central axis of the processing vessel 12 coincides with the axis PX. This processing container 12 provides a space S for performing plasma processing on a substrate W such as a wafer.

In one embodiment, the processing container 12 has a substantially constant width at an intermediate portion 12a in the height direction, that is, a portion that accommodates the support structure 11. Further, the processing container 12 has a tapered shape whose width gradually narrows from the lower end of the intermediate portion toward the bottom. Further, the bottom of the processing container 12 provides an exhaust port 12e, and the exhaust port 12e is formed axially symmetrically with respect to the axis PX.

A support structure 11 is provided within the processing container 12 . The support structure 11 attracts and holds the substrate W using an electrostatic chuck 31 . The support structure 11 is rotatable about a first axis AX1 orthogonal to the axis PX. The support structure 11 can be tilted with respect to the axis PX by rotating the tilted shaft portion 50 about the first axis AX1. In order to tilt the support structure 11, the tilt pre-clean device 10 has a drive device 24. The drive device 24 is provided outside the processing container 12 and generates a driving force for rotating the support structure 11 about the first axis AX1. Further, the support structure 11 is configured to rotate the substrate W around a second axis AX2 orthogonal to the first axis AX1. Note that when the support structure 11 is not tilted, the second axis AX2 coincides with the axis PX, as shown in FIG. On the other hand, when the support structure 11 is tilted, the second axis AX2 is tilted with respect to the axis PX, as shown in FIG. Details of the support structure 11 will be described later.

The exhaust system 20 is configured to reduce the pressure of the space inside the processing container 12 to a high vacuum of, for example, 10 ⁻⁸ Torr to 10 ⁻⁹ Torr (1.33×10 ⁻⁶ Pa to 1.33×10 ⁻⁷ Pa). has been done. In one embodiment, the exhaust system 20 includes an automatic pressure controller 20a, a cryopump or turbomolecular pump 20b, and a dry pump 20c. Turbomolecular pump 20b is provided downstream of automatic pressure controller 20a. The dry pump 20c is directly connected to the space inside the processing container 12 via a valve 20d. Further, the dry pump 20c is provided downstream of the turbo molecular pump 20b via a valve 20e.

An exhaust system 20 including an automatic pressure controller 20a and a turbomolecular pump 20b is attached to the bottom of the processing vessel 12. Further, an exhaust system 20 including an automatic pressure controller 20a and a turbo molecular pump 20b is provided directly below the support structure 11. Therefore, in this tilt pre-clean device 10, a uniform exhaust flow can be formed from the periphery of the support structure 11 to the exhaust system 20. Thereby, efficient evacuation can be achieved. Furthermore, it is possible to uniformly diffuse the plasma generated within the processing container 12.

In one embodiment, a shield 17 is removably provided on the upper side surface of the inner wall of the processing container 12 in the space S, and a shield 26 is removably provided on the lower side surface and the bottom surface. Further, a shield 21 is removably provided on a wall surface other than the mounting surface 11a of the support structure 11 and on the outer peripheral surface of the inclined shaft portion 50. The shields 17, 21, and 26 prevent byproducts (hereinafter also referred to as "depots") generated by etching from adhering to the inside of the processing container 12. The shields 17, 21, and 26 are constructed, for example, by blasting the surface of a base material made of aluminum or by additionally forming an aluminum sprayed film. The shield 26 is divided into a plurality of parts to form a labyrinth structure, and gas is guided to the exhaust system 20 through the gaps therebetween. Shields 17, 21, and 26 are replaced as appropriate.

An opening is provided in the ceiling of the processing container 12, and the opening is closed by a dielectric window 19. The dielectric window 19 is a plate-shaped body made of quartz glass or ceramics.

The gas supply unit 14 supplies a processing gas into the processing container 12 through channels 14a and 14b. Details of the gas supply section 14 will be described later with reference to FIG. 4.

The ICP (Inductively Coupled Plasma) source unit 16 excites the processing gas supplied into the processing chamber 12 . In one embodiment, the ICP source unit 16 is provided on a dielectric window 19 in the ceiling of the processing vessel 12 . Further, in one embodiment, the central axis of the ICP source unit 16 coincides with the axis PX. The space in the ICP source unit 16 above the dielectric window 19 is an atmospheric space, and the space inside the processing chamber 12 below the dielectric window 19 is a vacuum space.

The ICP source unit 16 has a high frequency antenna 53 and a shield member 52. High frequency antenna 53 is covered with shield member 52. The high-frequency antenna 53 is made of a conductor such as copper, aluminum, or stainless steel, and extends in a spiral shape about the axis PX. A high frequency power source 51 is connected to the high frequency antenna 53. The high frequency power source 51 is a high frequency power source for plasma generation.

When a high frequency wave of a predetermined frequency is supplied to the high frequency antenna 53 from the high frequency power supply 51 with a predetermined power, the high frequency wave passes through the dielectric window 19 and forms an induced magnetic field in the processing container 12. The introduced processing gas is excited. As a result, donut-shaped plasma is generated on the substrate W. These plasmas generate radicals and ions from the process gas. The frequency of the high frequency power supplied from the high frequency power supply 51 may be 13.56 MHz, 27 MHz, 40 MHz, or 60 MHz.

A shield plate 13 is arranged below the dielectric window 19 in the processing container 12 and above the positions of the flow channels 14a and 14b. The shield plate 13 is a thin quartz film, and is provided near the dielectric window 19 to prevent by-products generated by etching from flying from the substrate W side and adhering to the dielectric window 19.

The bias power supply unit 62 is configured to apply high frequency bias power to the support structure 11 to draw ions into the substrate W. The high frequency power supply 51, the high frequency antenna 53, the dielectric window 19, and the gas supply unit 14 function as a plasma generation unit that generates plasma in the space U for generating plasma.

A slit plate 15 is provided between the dielectric window 19 and the support structure 11 and below the shield plate 13. The slit plate 15 includes a quartz slit plate 15a in which a plurality of slits 15a1 are formed, and a quartz slit plate 15b arranged under the slit plate 15a and in which a plurality of slits 15b1 are formed. The slit plate 15a is an example of a first slit plate, and the slit 15a1 is an example of a slit formed in the first slit plate. The slit plate 15b is an example of a second slit plate, and the slit 15b1 is an example of a slit formed in the second slit plate.

The outer edge of the slit plate 15 is gripped in the circumferential direction by the inner wall of the processing container 12, and partitions a space U for generating plasma and a space S for performing plasma processing. The slit 15a1 is offset from the slit 15b1 in a direction opposite to the inclination direction of the mounting surface 11a of the support structure 11 (see FIG. 3), and the slit 15a1 and the slit 15b1 do not overlap in plan view.

The side wall of the processing chamber 12 in the space U for generating plasma above the slit plate 15a is covered with a cylindrical quartz member 18. The insulating properties of the quartz member 18 prevent the plasma generated in the space U from being drawn into the processing container 12 connected to the ground and disappearing.

The control unit Cnt is, for example, a computer including a processor, a storage unit, an input device, a display device, and the like. The control unit Cnt operates according to a program based on the input recipe and sends out a control signal. Each part of the tilt pre-clean device 10 is controlled by a control signal from a control unit Cnt.

Each of the structures for holding the support structure 11, the gas supply section 14, and the shield plate 13 will be described in detail below.

[Support structure]
As shown in FIG. 3, the support structure 11 places the substrate W on the inclined mounting surface 11a, and supports the substrate W so as to be rotatable at a predetermined tilt angle in the vertical direction. FIG. 1 shows a cross-sectional view of the support structure 11 viewed from the Y direction, and FIG. 3 shows a cross-sectional view of the support structure 11 viewed from the X direction. As shown in FIGS. 1 and 3, the support structure 11 includes a holding section 30, a container section 40, and an inclined shaft section 50.

The holding unit 30 is a mechanism that holds the substrate W and rotates the substrate W in the horizontal direction by rotating around the second axis AX2. Note that, as described above, the second axis AX2 coincides with the axis PX when the support structure 11 is not inclined. The holding section 30 includes an electrostatic chuck 31, a lower electrode 32, and a rotating shaft section 33.

The electrostatic chuck 31 holds the substrate W on the mounting surface 11a, which is its upper surface. The electrostatic chuck 31 has a substantially disk shape with the second axis AX2 as its central axis, and includes an electrode film provided as an inner layer of an insulating film. The electrostatic chuck 31 generates electrostatic force when a voltage is applied to the electrode film. Due to this electrostatic force, the electrostatic chuck 31 electrostatically attracts the substrate W placed on the mounting surface 11a. A heat transfer gas such as He gas or Ar gas is supplied between the electrostatic chuck 31 and the substrate W. Further, a heater for heating the substrate W may be built in the electrostatic chuck 31. This electrostatic chuck 31 is provided on the lower electrode 32.

Referring to FIGS. 1 and 2, the lower electrode 32 has a substantially disk shape with the second axis AX2 as its central axis. The lower electrode 32 is made of a conductor such as aluminum. The lower electrode 32 is electrically connected to the bias power supply section 62 . The electrostatic chuck 31 is provided with a coolant channel, and the temperature of the substrate W is controlled by supplying the coolant to the coolant channel.

The rotating shaft portion 33 has a substantially cylindrical shape and is coupled to the lower surface of the lower electrode 32 at the center. The central axis of the rotating shaft portion 33 coincides with the second axis AX2. By applying a rotational force to the rotating shaft portion 33, the holding portion 30 rotates.

The holding section 30 having such a configuration forms the support structure 11 together with the container section 40. A through hole through which the rotating shaft portion 33 passes is formed in the center of the container portion 40 . A magnetic fluid seal section 104 is provided between the container section 40 and the rotating shaft section 33. The magnetic fluid seal portion 104 hermetically seals the internal space of the support structure 11 . The magnetic fluid seal portion maintains the internal space of the support structure 11 at atmospheric pressure and isolates it from the vacuum space S.

Furthermore, with reference to FIG. 2, the internal structure of the container section 40 will be described in detail. FIG. 2 is a diagram showing an example of the internal structure of the container section 40 of FIG. 1. A rotary joint (rotary refrigerant joint) 102 for supplying refrigerant to the refrigerant flow path 101 is arranged around the rotation shaft portion 33 on the outer periphery of the rotation shaft portion 33, and a rotary joint (rotary refrigerant joint) 102 is arranged around the rotation shaft portion 33 to supply refrigerant to the refrigerant flow path 101. A refrigerant is supplied to the flow path 31a. A hollow cylindrical lower electrode holding portion 103 is arranged around the outer periphery of the rotary joint 102 . Further, a magnetic fluid sealing part 104 is disposed around the outer periphery of the lower electrode holding part 103 for sealing the vacuum space S in the processing container 12 from the atmospheric space in the container part 40 . By arranging the rotary joint 102 inside the magnetic fluid sealing part 104 in this way, it is not necessary to extend the rotating shaft part 33 in the direction of the axis AX2 in order to arrange the rotary joint 102. As a result, the length of the container portion 40 in the axis AX2 direction can be shortened, so the support structure 11 can be tilted significantly without increasing the internal volume of the processing container 12. This makes it possible to reduce the footprint.

A slip ring 105 is arranged below the rotary joint 102 for supplying power to the chuck electrode 31b and heater 31c of the electrostatic chuck 31 and for applying a bias. In the space between the outer periphery of the magnetic fluid sealing part 104 and the inner inner wall of the container part 40, a lifter pin 107a for lifting up and down the rotation motor 106 of the rotating shaft part 33 and the substrate W from the holding part 30 is provided. A lift mechanism 107 including a lift mechanism 107 is arranged. Further, a gas line 108 for supplying backside gas to the back surface of the substrate W can be provided in the rotating shaft portion 33 and the lower electrode holding portion 103 as appropriate.

Returning to FIG. 1, the inner end portion of the inclined shaft portion 50 is fitted into the opening formed in the container portion 40. The inclined shaft portion 50 is offset to the height of the substrate W before reaching the processing container 12. Thereby, the first axis AX1 is at the same height as the substrate, and the center of the substrate W is located on the second axis AX2 no matter what angle the container section 40 is tilted. Thereby, a margin for process controllability can be provided. Further, the inclined shaft portion 50 extends to the outside of the processing container 12, as shown in FIG. A drive device 24 is coupled to one outer end of the inclined shaft portion 50 .

The drive device 24 pivotally supports one outer end of the inclined shaft portion 50 . By rotating the tilting shaft part 50 by the drive device 24, the support structure 11 is rotated in the vertical direction about the first axis AX1, and as a result, the support structure 11 is tilted with respect to the axis PX. It has become. For example, the support structure 11 may be tilted such that the second axis AX2 forms an angle within 0 degrees to 90 degrees with respect to the axis PX.

Various electrical system wiring, heat transfer gas piping, and refrigerant piping are passed through the inner hole of the inclined shaft portion 50. These wiring and piping are connected to the rotating shaft portion 33.

As shown in FIG. 2, a rotation motor 106 is provided in the internal space of the support structure 11. The rotation motor 106 generates a driving force for rotating the rotation shaft portion 33. In one embodiment, the rotation motor 106 is provided on the side of the rotation shaft portion 33. The rotation motor 106 is connected to a pulley attached to the rotating shaft portion 33 via a transmission belt. Thereby, the rotational driving force of the rotation motor 106 is transmitted to the rotating shaft portion 33, and the holding portion 30 rotates in the horizontal direction about the second axis AX2. The rotation speed of the holding part 30 is, for example, within a range of 48 rpm or less. For example, the holding part 30 is rotated at a rotation speed of 20 rpm during the process. Note that the wiring for supplying power to the rotation motor 106 is drawn out to the outside of the processing container 12 through the inner hole of the inclined shaft portion 50, and is connected to a power source for the motor provided outside the processing container 12. Ru.

In this way, the support structure 11 can provide various mechanisms in the internal space that can be maintained at atmospheric pressure. The support structure 11 also connects wiring or piping to the outside of the processing container 12 for connecting the mechanism housed in its internal space to devices such as a power source, a gas source, and a chiller unit provided outside the processing container 12. It is configured so that it can be pulled out. In addition to the wiring and piping described above, wiring connecting the heater power supply provided outside the processing container 12 and the heater provided in the electrostatic chuck 31 is connected from the internal space of the support structure 11 to the processing container 12. It may be pulled out to the outside of the inclined shaft portion 50 through the inner hole.

[Gas supply system]
Next, the gas supply system will be explained with reference to FIG. 4, which shows a cross section taken along line AA in FIG. The gas supply section 14 is connected to a gas introduction pipe 14c. The gas introduction pipe 14c is branched and connected to a flow path 14c1 and a flow path 14c2 formed inside the inner wall of the processing container 12. The flow path 14c1 and the flow path 14c2 are formed in semicircular shapes opposite to each other in the circumferential direction, and are connected to a flow path 14a and a flow path 14b that extend substantially perpendicularly inward in the radial direction at their respective ends.

The flow path 14a branches into a flow path 14a1 and a flow path 14a2 that are formed in the circumferential direction inside a quartz member 18 that covers the inner wall of the processing container 12. Gas holes 22a, 22b, 22c, and 22d that open toward the center of the processing container 12 at equal intervals are formed in the flow path 14a1 and the flow path 14a2.

The flow path 14b branches into a flow path 14b1 and a flow path 14b2 that are formed in the circumferential direction inside the quartz member 18 on the opposite side of the flow path 14a1 and the flow path 14a2. Gas holes 22e, 22f, 22g, and 22h that open toward the center of the processing container 12 at equal intervals are formed in the flow path 14b1 and the flow path 14b2. The flow path 14a1 and the flow path 14a2, and the flow path 14b1 and the flow path 14b2 are vertically separated and formed approximately in a ring shape on the same circumference, and have eight gas holes 22a, 22b, 22c, 22d, 22e, 22f, 22g, and 22h (hereinafter also collectively referred to as "gas holes 22") are arranged at equal intervals.

With this configuration, the gas supply unit 14 introduces the processing gas into the space U for generating plasma through the eight gas holes 22 arranged at equal intervals. The processing gas introduced into the processing container 12 from the eight gas holes 22 at equal intervals is turned into plasma by the RF power introduced from the ICP source unit 16 via the high frequency antenna 53, and thereby, the processing gas is uniformly distributed in the space U. Can generate plasma. Note that the number of gas holes is not limited to eight, and a plurality of gas holes may be provided at equal intervals in the circumferential direction with respect to the axis PX.

Gas supply 14 may include one or more gas sources, one or more flow controllers, and one or more valves. Therefore, the flow rate of the processing gas from one or more gas sources in the gas supply section 14 is adjustable. The flow rate of the processing gas from the gas supply section 14 and the timing of supply of the processing gas are individually adjusted by the control section Cnt.

[Structure for holding the shield plate]
Next, a structure for holding the shield plate 13 will be described with reference to FIG. 5. The outer edge (outer periphery) of the shield plate 13 is held with an elastic body 23 sandwiched between the processing container 12 and a ring-shaped clamp 25 provided at a step formed on the side wall of the processing container 12. There is. The elastic body 23 is a spiral-shaped cushioning material disposed between the lower surface of the outer edge of the shield plate 13 and a stepped portion formed on the side wall of the processing container 12 . The elastic body 23 may be composed of a metal spiral ring, for example.

The shield plate 13 repeatedly expands and compresses due to the heat from the plasma generated in the space U. As a result, tensile stress and compressive stress are applied to the shield plate 13. In contrast, in the structure for gripping the shield plate 13 of this embodiment, the outer edge of the shield plate 13 is movable between the clamp 25 and the elastic body 23. Therefore, the structure is such that damage such as cracking of the shield plate 13 does not occur due to the above stress.

[Shield structure]
Next, a problem that occurs when conductive by-products generated by etching the substrate W adheres to the dielectric window 19, which is a window for introducing radio frequency (RF) and serves as a vacuum partition wall, will be described. When a metal film is formed on the dielectric window 19, the metal film prevents high frequencies from passing through the dielectric window 19. In addition, the high frequency waves are absorbed by the metal film formed on the dielectric window 19 and turned into heat, causing eddy current heating, resulting in a decrease in the amount of high frequency waves introduced and the risk of the dielectric window 19 breaking due to thermal stress. . Therefore, it becomes necessary to periodically replace the dielectric window 19 on which the metal film is formed.

In order to solve this problem, if the shield structure using the slit plate 15 and the shield plate 13 is made to have a structure specialized for the function of preventing adhesion to the dielectric window 19, the ions necessary for etching the substrate W can be supplied to the slit. This may be obstructed by the plate 15 and cause a decrease in the etching rate. Therefore, it is desirable to efficiently extract ions in the plasma toward the substrate W to etch the substrate W. In other words, it is important to establish a structure that achieves both the maintenance of the adhesion prevention function to the dielectric window 19 and the ion extraction function.

On the other hand, in one embodiment, a shield plate 13 is arranged directly below (vacuum side) the dielectric window 19 which is a vacuum partition, and a slit plate 15 is provided between the space U for generating plasma and the substrate W. It has a shield structure in which two sheets are arranged. Further, the slits 15a1 and 15b1 of the two slit plates 15a and 15b are alternated, and a shield structure is formed in which the space U for directly generating plasma vertically from the substrate W side through the slits is not visible. This can prevent by-products during etching from adhering to the dielectric window 19 as a metal film.

As the slit width (SW in FIG. 6) of the slit plates 15a and 15b is narrowed, the effect of preventing adhesion to the dielectric window 19 increases, but the supply of ions to the substrate W side is hindered and the etching rate decreases. Therefore, in this embodiment, the width, position, etc. of each slit 15a1, 15b1 of the slit plates 15a, 15b are optimized. Thereby, it is possible to enhance the effect of preventing adhesion to the dielectric window 19 and prevent a decrease in the etching rate.

In particular, the support structure 11 on which the substrate W is placed has a function of controlling rotation and tilt angle. Therefore, the substrate W is tilted by the support structure 11 within the range of 0 degrees to 90 degrees, and the positional relationship between the slits 15a1 and 15b1 is adjusted appropriately. As a result, a shield structure is achieved that both ensures the amount of ions extracted from the space U for generating plasma and suppresses the amount of etching by-products passing through from the substrate W. The shield structure according to this embodiment will be described in more detail below.

[Slit plate]
As shown in the lower diagram of FIG. 6, which is an enlarged view of the upper part of the processing container 12 in FIG. The positions are staggered. That is, the slits 15a1 and 15b1 are in a positional relationship that does not overlap in plan view. Hereinafter, the positional relationship in which the slits 15a1 and 15b1 are alternated will also be referred to as "offset".

The tilt pre-clean device 10 has a structure in which the support structure 11 can control the rotation of the substrate W and the tilt angle of the mounting surface 11a. The tilt angle of the mounting surface 11a is adjusted within the range of 0 degrees to 90 degrees. In the example of FIG. 7, the tilt angle of the mounting surface 11a is adjusted to 45 degrees. In this way, by combining the control of the rotation of the substrate W and the tilt angle of the mounting surface 11a by the support structure 11, and the adjustment of the width and position of each slit 15a1, 15b1 of the slit plates 15a, 15b, the adhesion prevention performance is improved. This makes it possible to simultaneously secure the etching rate. In addition, by arranging the shield plate 13 directly under the dielectric window 19, by-products are prevented from adhering to the dielectric window 19, which is a window for introducing high frequency waves, and maintenance-free dielectric window 19 is achieved. It is possible to improve maintainability.

Adjustment of the width and position of each slit 15a1, 15b1 of the slit plates 15a, 15b will be specifically explained with reference to FIG. FIG. 7 is a diagram for explaining the width and position of the slits 15a1 and 15b1 and the movement of by-products (deposits) due to ion etching according to one embodiment. As shown in FIG. 7, ionized argon ions (Ar ⁺ ) in the space U for generating plasma on the slit plate 15 are drawn out to the substrate W side through the slits 15a1 and 15b1, and the action of the argon ions is It is important to ensure an etching rate that satisfies the process conditions. Furthermore, it is important to prevent the deposit from flying into the space U through the slits 15a1 and 15b1 and adhering to the dielectric window 19. In order to achieve both of these trade-offs (prevention of adhesion to the dielectric window 19 and the like and drawing of argon ions to the substrate W), in this embodiment, the substrate W (mounted) by the support structure 11 is The inclination of the surface 11a) and the offset of the slits 15a1 and 15b1 are combined. Note that argon ions are an example of ions, and the ion type is not limited to this, and the type of ions varies depending on the type of gas supplied from the gas supply unit 14.

To create an offset positional relationship between the slits 15a1 and 15b1 that makes it easy to extract argon ions necessary for etching from the space U and makes it difficult to directly see the shield plate 13 from the tilted substrate W, the slits 15a1 and 15b1 should be offset. The direction of is important.

Therefore, the offset direction of the slits 15a1 and 15b1 is optimized by taking advantage of the fact that the substrate W tilts only in a certain direction. For example, in the example shown in FIG. 7, the substrate W is rotated around the axis PX while being tilted in the upper left direction (in FIG. 7, the angle θ with respect to the horizontal direction is 45 degrees) with the axis PX as the center. . The turning direction at that time is shown by an arrow R, and the turning locus of the outer diameter of the substrate W (for example, diameter 200 mm) is shown by a circle PA.

The positions of the slits 15a1 and 15b1 of the two slit plates 15a and 15b are offset with respect to the inclination of the substrate W, so that argon ions can easily reach the substrate W through the two slit plates 15a and 15b. do. Therefore, the slit 15a1 is located in the turning direction of the support structure 11 rather than the center between the two slits 15b1 adjacent to the slit 15a1. In other words, the slit 15a1 is located in the direction in which the substrate W is inclined (here, to the left) with respect to the center between the two slits 15b1 adjacent to the slit 15a1. This makes it easier for the argon ions generated in the space U to pass through the slit 15a1 offset with respect to the slit 15b1, and to enter the space S for performing plasma processing through the slit 15b1. Due to the offset between the slit 15a1 and the slit 15b1, the argon ions enter the space S diagonally downward to the left, move radially, and are more likely to be incident on the substrate W which is tilted diagonally upward to the left. The etching rate is determined by the number of ions drawn into the substrate W from the space U through the slits 15a1 and 15b1. According to this configuration, the number of argon ions incident on the space S can be increased and the etching rate can be increased by adjusting the offset positional relationship of the slits 15a1 and 15b1.

Deposits generated during etching by bombarding the substrate W with argon ions fly toward inner walls such as the ceiling and side walls of the processing container 12 . However, taking advantage of the fact that the substrate W is tilted in a certain direction, the slit 15a1 is offset from the slit 15b1 in a direction in which the dielectric window 19 is difficult to see from the substrate W side. Therefore, most of the deposits flying toward the ceiling within the space S attach to the lower surface of the slit plate 15b or pass through the slit 15b1 and adhere to the lower surface of the slit plate 15a. Thereby, it is possible to suppress deposits from adhering to the dielectric window 19 and formation of a metal film on the dielectric window 19.

From the above, the slit 15a1 is located in the turning direction of the support structure 11 rather than the center between the two slits 15b1 adjacent to the slit 15a1. That is, the slits 15a1 and 15b1 are offset to positions where argon ions are easily sputtered onto the surface of the substrate W and deposits are difficult to pass through the slits 15a1 and 15b1. Thereby, while efficiently etching the substrate W, it is possible to suppress by-products formed by etching from adhering to the dielectric window 19 for introducing high frequency waves.

The upper diagram in FIG. 6 shows an enlarged area within the C frame in the lower diagram in FIG. 6 . By optimizing the position between the slits 15a1 and 15b1 which are offset from each other, a structure is created in which a large amount of the deposited metal film generated when the substrate W is etched does not adhere to the shield plate 13 and the dielectric window 19. ing.

The distance between the lower surface of the slit plate 15a and the upper surface of the slit plate 15b is defined as "SD", and each width of the slit 15a1 and the slit 15b1 is defined as "SW". Each width of the slit 15a1 and the slit 15b1 is the same. Increasing the slit width SW makes it easier for argon ions to pass through and increases the etching rate, but the effect of preventing adhesion to the dielectric window 19 decreases. As the distance between the slits 15a1 and 15b1 increases, the etching rate decreases, but the effect of preventing adhesion to the dielectric window 19 improves.

As shown in the upper diagram of FIG. 6, while plasma is being generated, ion sheaths Sh are generated on the surfaces of the quartz slit plates 15a and 15b. When the argon ions touch the sheath while moving between the slit plates 15a, 15b, the argon ions disappear. From the above, as the distance SD between the slit plates 15a and 15b becomes smaller, the probability that ions collide with the slit plates increases, so the number of argon ions that disappear increases and the etching rate decreases.

Note that the intervals between the slits 15a1 and the intervals between the slits 15b1 may or may not be the same pitch. Moreover, the longitudinal directions of the slits 15a1 and 15b1 are arranged in the same direction. That is, the corresponding slits 15a1 and 15b1 of the upper and lower slit plates 15a and 15b are shifted by the same amount.

A simulation was performed to find an appropriate value for the offset between the slits 15a1 and 15b1. The appropriate value of the offset between the slits 15a1 and 15b1 will be explained with reference to FIG. FIG. 8 is a diagram illustrating an example of a simulation for optimizing the position of the slit according to one embodiment.

The conditions for the simulation are as follows.
・Slit plate: 2 discs with a diameter of 150 mm, top and bottom ・Slit width SW 8.5 mm
・Thickness of each slit plate: 5mm
・Slit plate spacing SD 8.5mm
In FIG. 8A, the slit 15a1 is located less in the rotation direction of the support structure 11 than the central axis O between the adjacent slits 15b1. In other words, the slit 15a1 is not located in the direction in which the substrate W is inclined (to the left in FIG. 7) with respect to the central axis O between the slits 15b1 adjacent to the slit 15a1.

On the other hand, in FIG. 8(b), the slit 15a1 is located in the rotation direction of the support structure 11 with respect to the central axis O between the adjacent slits 15b1. In other words, the slit 15a1 is located in the direction in which the substrate W is inclined (leftward in FIG. 7) with respect to the central axis O between the slits 15b1 adjacent to the slit 15a1.

As a result of calculating the etching results of six substrates W (200 mm wafers) using the offset shown in FIG. 8(a) and the offset shown in FIG. 8(b), the results showed that the offset shown in FIG. 8(b) In this case, the in-plane etching distribution of each of the six substrates W varied by 2.62 to 2.95%. On the other hand, in the case of the offset shown in FIG. 8(a), the in-plane distribution of etching on the six substrates W became uneven and the etching rate was lower than in the case of the offset shown in FIG. 8(b). .

From the above, the offset value is determined so that the slit 15a1 is located in the rotation direction of the support structure 11 (the direction of inclination indicated by the tilt angle θ in FIG. 7) with respect to the center between the slits 15b1 adjacent to the slit 15a1. is found to be appropriate. That is, as shown in FIG. 7, when the substrate W is tilted diagonally upward to the left, the position of the slit 15a1 based on the slit 15b1 is shifted to the left in the turning direction from the center between the slits 15b1. Thereby, an appropriate offset positional relationship between the slits 15a1 and 15b1 can be established, the number of argon ions entering the space S can be increased, and the etching rate can be increased. In addition, since the substrate W is tilted diagonally upward to the left, the slits 15a1 and 15b1 are offset to positions where it is difficult for the deposit to pass through the slits 15a1 and 15b1. Thereby, while efficiently etching the substrate W, it is possible to suppress by-products formed by etching from adhering to the dielectric window 19.

[Modified example]
The plasma distribution has a high density at the center above the substrate W. In order to obtain a good etching distribution, it is important to uniformly supply gas to the space U for generating plasma and to have a structure that controls the ion distribution on the substrate W. Therefore, next, a slit plate 15 according to a modification of the embodiment will be described with reference to FIG. 9. FIG. 9 is a diagram showing an example of a simulation result for optimizing the masking of the slits 15a1 and 15b1 according to a modification of the embodiment.

In the embodiment described above, the slits 15a1 and 15b1 are formed at regular intervals over the entire surface of the slit plates 15a and 15b, as shown in the slit plate 15a "without mask" in FIG. 9(a). In FIG. 9, the slit 15b1 on the lower side of the slit plate 15a is not shown.

On the other hand, in the slit plate 15 according to a modification of the embodiment, the slit plate is designed based on the fact that plasma is likely to be formed on the center side of the substrate W, and the plasma density is likely to be higher on the center side of the substrate W than on the outer peripheral side. Mask the center part of 15. Specifically, as shown in FIGS. 9(b) to 9(e), in order to spread the plasma, the slits 15a1 and 15b1 are not opened at the centers of the slit plates 15a and 15b, but only at the outer peripheries of the slit plates 15a and 15b. It has a structure in which slits 15a1 and 15b1 are arranged. That is, the slits 15a1 and 15b1 located at the center of the slit plates 15a and 15b are closed by the mask M, thereby allowing ions in the plasma to pass into the space S through the slits 15a1 and 15b1 opened at the outer periphery of the slit plates 15a and 15b. Thereby, ions drawn into the substrate W can be prevented from concentrating on the center of the substrate W, and variations in the etching in-plane distribution can be reduced.

The simulation conditions when etching a substrate W having a diameter of 200 mm are as follows.
・Slit plate diameter 400mm, 2 pieces above and below ・Slit width SW 8.5mm
・Thickness of slit plate 5mm
・Slit plate spacing SD 8.5mm
The bar graph in FIG. 9 shows the degree of variation in the in-plane etching distribution with respect to the presence or absence and size of the masks M provided on the slit plates 15a and 15b.

FIG. 9(a) shows that the variation in the etching in-plane distribution when etching is performed based on argon ions extracted from the slits 15a1 and 15b1 of the slit plates 15a and 15b when there is no mask M is 10.4%. show.

FIGS. 9(b) to 9(e) show the etched surfaces when etching is performed based on extracted argon ions when a predetermined area from the center of the slits 15a1 and 15b1 of the slit plates 15a and 15b is covered by the mask M. Each shows the variation in the internal distribution. The mask M in FIG. 9(b) is a circle with a diameter of 100 mm. The mask M in FIG. 9(c) is a circle with a diameter of 150 mm. The mask M in FIG. 9(d) is a circle with a diameter of 200 mm. The mask M in FIG. 9(e) is a circle with a diameter of 250 mm.

As a result, when a predetermined area from the center of the slit plates 15a and 15b is covered by the mask M, the variation in the etching in-plane distribution is 4.5% to 6.9%, compared to the case where the mask M is not provided. You can see that it becomes smaller. It can also be seen that the larger the mask M is, the smaller the variation in the etching in-plane distribution becomes.

However, as the mask M becomes larger, the number of ions reaching the substrate W decreases, and thus the etching rate decreases. Therefore, the size of the mask M is appropriately 60 to 90% of the size of the substrate W. Thereby, the etching rate of the substrate W can be maintained while reducing variations in the in-plane etching distribution. Note that even if both of the two slit plates 15a and 15b are not masked, it is sufficient that at least one of them is masked.

According to this, by using the mask M to block the slit in the center of the plasma generated by the ICP source unit 16 and having a high density in the center, it is possible to reduce variations in the in-plane etching distribution. By combining this configuration with the support structure 11 having the function of rotating and tilting the substrate W, it is possible to ensure a good in-plane etching distribution.

Further, the area masked by the mask M is preferably a circle having a diameter within a range of 60% to 90% from the center of the diameter of the substrate W placed on the placement surface 11a. This makes it possible to maintain the etching rate while reducing variations in the etching in-plane distribution.

The tilt pre-clean device 10 can be used to clean the inside of the processing container 12 before film formation. Further, the tilt pre-clean device 10 can be used to remove oxides on the substrate W between the formation of one film and the next film, or to thin and planarize the formed film.

Since the tilt pre-clean apparatus 10 is in a high vacuum (10 ^-8 Torr to 10 ^-9 Torr) when performing plasma processing, once the inside of the processing container 12 is changed from a vacuum state to an atmospheric state during maintenance, the next substrate W is It takes time to create a vacuum state during processing. Therefore, the shields 1, 21, and 26 placed in the processing container 12 are provided with a function that allows byproducts from etching to be deposited for a certain period of time while maintaining process performance, thereby minimizing equipment downtime. Therefore, maintenance (shield replacement) will be performed at the same time as other processing equipment.

In such a situation, the tilt pre-clean device 10 has a shield structure using the slit plate 15 and the shield plate 13, so that by-products formed by etching can be removed from the dielectric window while efficiently etching the substrate W. It is possible to suppress adhesion to 19.

The plasma processing apparatus according to the embodiment and the modified example disclosed this time should be considered to be illustrative in all respects and not restrictive. The embodiments described above can be modified and improved in various ways without departing from the scope and spirit of the appended claims. The matters described in the plurality of embodiments described above may be configured in other ways without being inconsistent, and may be combined without being inconsistent.

10 Tilt pre-clean device 11 Support structure 12 Processing container 13 Shield plate 14 Gas supply part 15 Slit plate 15a Slit plate 15a1 Slit 15b Slit plate 15b1 Slit 16 ICP source unit 17, 21, 26 Shield 18 Quartz member 19 Dielectric window 25 Clamp 30 Holding part 31 Electrostatic chuck 32 Lower electrode 33 Rotating shaft part 40 Container part 50 Inclined shaft part 51 High frequency power supply 53 High frequency antenna 102 Rotary joint 103 Lower electrode holding part 104 Magnetic fluid seal part 105 Slip ring 106 Rotation motor 107 Lift Mechanism S Space for plasma processing U Space for generating plasma

Claims (10)

A plasma processing apparatus that performs plasma processing on a substrate,
a plasma generation unit that generates plasma in the processing container;
a support structure that rotatably supports the substrate by placing the substrate on an inclined mounting surface within the processing container;
a first slit plate made of quartz provided between the plasma generation section and the support structure and having a first slit formed therein;
a second slit plate made of quartz that is provided between the plasma generation unit and the support structure under the first slit plate and has a second slit formed therein;
The first slit is offset from the adjacent second slit in a direction opposite to the direction of inclination of the mounting surface.
Plasma processing equipment. The plurality of first slits are located in the rotation direction of the support structure relative to the central axis between the two adjacent second slits,
The plasma processing apparatus according to claim 1. The first slit and the second slit do not overlap in plan view,
The plasma processing apparatus according to claim 1 or 2. At least one of the first slit plate and the second slit plate is masked in a radial direction from the center of the first slit plate and the second slit plate,
The plasma processing apparatus according to any one of claims 1 to 3. The masked area is a circle having a diameter ranging from 60% to 90% from the center of the diameter of the substrate placed on the placement surface.
The plasma processing apparatus according to claim 4. The plasma generation section has a high frequency antenna,
A quartz shield plate is disposed below the dielectric window that transmits high frequency waves from the high frequency antenna.
The plasma processing apparatus according to any one of claims 1 to 5. The outer edge of the shield plate is held between an elastic body and a clamp provided at a step formed on a side wall of the processing container.
The plasma processing apparatus according to claim 6. A side wall of the processing container forming a space for generating plasma above the first slit plate is covered with a cylindrical quartz member.
The plasma processing apparatus according to any one of claims 1 to 7. The plasma generation section has a gas supply section that supplies gas,
The gas supply unit introduces gas into the space for generating the plasma from a plurality of gas holes provided at equal intervals on the side wall of the quartz member.
The plasma processing apparatus according to claim 8. A magnetic fluid sealing portion is provided inside the container portion of the support structure for sealing the inside of the processing container from the space within the container portion;
disposing a rotary joint inside the magnetic fluid seal portion;
The plasma processing apparatus according to any one of claims 1 to 9.

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