KR20200122208A - Capacitively-coupled plasma substrate processing apparatus including a focus ring and a substrate processing method using the same - Google Patents

Abstract

The present invention relates to a substrate processing device comprising: a processing chamber; a shower head; a fixing ring; and a support. The shower head includes: an upper electrode; and an electrode support body. The support includes: an electrostatic chuck; and a ring unit. The electrostatic chuck may include: a lower electrode; and a dielectric layer. The ring unit includes: a focus ring; and a covering ring. The focus ring includes a lower layer containing Al_2O_3 and an upper layer containing Si on the lower layer. The thickness of the dielectric layer is 3 to 4 mm, and the thickness of the lower layer of the focus ring is 0.25 to 0.4 times the thickness of the focus ring. The fixing ring overlaps with a part of a cover ring in the top view, and a vertical line aligned with an inner surface of the fixing ring is spaced apart from the vertical line perpendicular to an inner surface of the cover ring by a predetermined distance, wherein the predetermined distance may be greater than 3/4 of the width of an upper surface of the cover ring and smaller than the width of the upper surface of the cover ring.

Description

Capacitively coupled plasma substrate processing apparatus including focus ring and substrate processing method using the same {CAPACITIVELY-COUPLED PLASMA SUBSTRATE PROCESSING APPARATUS INCLUDING A FOCUS RING AND A SUBSTRATE PROCESSING METHOD USING THE SAME}

The present disclosure relates to a capacitively coupled plasma substrate processing apparatus and a substrate processing method using the same.

As semiconductor devices are miniaturized, demand for a high aspect ratio pattern structure increases, and as the substrate becomes larger, etching defects occur in the edge region of the substrate even with a slight change in plasma uniformity. As a result, the yield of the edge region of the substrate in the plasma etching process is significantly reduced. Accordingly, there is a need to develop a new plasma etching apparatus capable of increasing plasma uniformity.

Tasks according to embodiments of the present disclosure A capacitively coupled plasma substrate processing apparatus and a substrate processing method using the apparatus for increasing a process speed and production yield by evenly distributing plasma density in a plasma process for processing a semiconductor substrate using plasma. To provide.

An apparatus for processing a capacitively coupled plasma substrate according to an embodiment of the present disclosure includes: a process chamber; A shower head positioned above the process chamber; A fixing ring positioned at the upper portion of the process chamber and near the outer side of the shower head; A support disposed below the process chamber, the shower head including an upper electrode on the support, the support comprising: an electrostatic chuck disposed under the upper electrode; And a ring unit disposed on the electrostatic chuck, wherein the electrostatic chuck comprises: a lower electrode on which the ring unit is mounted; And a dielectric layer disposed on the lower electrode, wherein the ring unit comprises: a focus ring surrounding an outer portion of the dielectric layer; And a cover ring disposed outside the focus ring, wherein the focus ring includes a lower layer containing Al ₂ O ₃ and an upper layer containing Si on the lower layer, wherein the dielectric layer has a thickness of 3 to 4 mm Or less, wherein the thickness of the lower layer of the focus ring is 0.25 to 0.4 times the thickness of the focus ring, and the fixing ring overlaps a part of the cover ring in a top view, but a vertical line aligned with the inner surface of the fixing ring is the cover It is spaced apart from a vertical line perpendicular to the inner surface of the ring by a predetermined distance, and the predetermined distance may be greater than 3/4 times the width of the upper surface of the cover ring and smaller than the width of the upper surface of the cover ring.

An apparatus for processing a capacitively coupled plasma substrate according to an embodiment of the present disclosure includes: a process chamber; A shower head positioned above the process chamber; A fixing ring located near the outside of the shower head; It includes a support positioned under the shower head, the shower head includes an upper electrode in which a spray hole is formed, the support includes an electrostatic chuck and a ring unit disposed on the electrostatic chuck, the electrostatic chuck , A lower electrode and a dielectric layer on the lower electrode, wherein the ring unit includes: a focus ring disposed outside the lower electrode; And a cover ring disposed outside the focus ring on the lower electrode, wherein the focus ring has a width of an upper surface of 2 to 10 times a width of an upper surface of the cover ring, and the fixing ring is the cover in a top view. It overlaps with a part of the ring, but a vertical line aligned with the inner surface of the fixed ring is spaced apart from a vertical line perpendicular to the inner surface of the cover ring by a predetermined distance, and the predetermined distance is 3/4 of the width of the upper surface of the cover ring. It may be larger than a ship and smaller than the width of the upper surface of the cover ring.

A substrate processing method using a capacitively coupled plasma substrate processing apparatus according to an exemplary embodiment of the present disclosure includes loading a substrate on an electrostatic chuck disposed in a process chamber included in the substrate processing apparatus; Supplying a processing gas onto the substrate in the process chamber; Generating plasma by providing an RF signal to the electrostatic chuck; And processing the substrate using the plasma, wherein the substrate processing apparatus comprises: a ring unit disposed on the electrostatic chuck, a shower head disposed on the electrostatic chuck and the ring unit, and an upper portion of the process chamber And a fixing ring positioned at a corner, wherein the electrostatic chuck includes a lower electrode to which the RF signal is provided and a dielectric layer on the lower electrode, and the ring unit includes a focus ring adjacent to the substrate and an outer side of the focus ring. It includes a cover ring disposed, the thickness of the dielectric layer is 3 ~ 4mm or less, the focus ring includes an upper layer containing Si and a lower layer containing Al ₂ O ₃ , the upper layer includes a concave recess, , A vertical line aligned with the inner surface of the fixing ring is spaced apart from a vertical line perpendicular to the inner surface of the cover ring by a predetermined distance, and the predetermined distance is greater than 3/4 of the width of the upper surface of the cover ring and the upper surface of the cover ring May be smaller than the width of

According to the exemplary embodiment of the present disclosure, the capacitively coupled plasma substrate processing apparatus may increase a radius at which plasma is generated by reducing an impedance difference between an electrostatic chuck on which a substrate is mounted and a focus ring disposed at an edge of the electrostatic chuck against high frequency power. The high-density plasma region located on the edge region of the substrate may be generated outside the edge region of the substrate, so that a uniform etch rate may appear over the entire substrate.

1 is a schematic cross-sectional view of a substrate processing apparatus according to an exemplary embodiment of the present disclosure.
FIG. 2 is a perspective cross-sectional view illustrating a focus ring, a cover ring, a protruding electrode, and a fixing ring included in the substrate processing apparatus of FIG. 1.
3 is a graph showing an etch rate according to an area of a substrate in a conventional substrate processing apparatus.
4 is an enlarged cross-sectional view of region P according to the exemplary embodiment of FIG. 1.
5A is an enlarged cross-sectional view of area P according to the exemplary embodiment of FIG. 1.
5B is an enlarged cross-sectional view of region P according to the exemplary embodiment of FIG. 1.
6A is an enlarged cross-sectional view of region P according to the exemplary embodiment of FIG. 1.
6B is an enlarged cross-sectional view of region P according to the exemplary embodiment of FIG. 1.
7A is an enlarged cross-sectional view of area P according to the exemplary embodiment of FIG. 1.
7B is an enlarged cross-sectional view of region P according to the exemplary embodiment of FIG. 1.
8A is an enlarged cross-sectional view of region P according to the exemplary embodiment of FIG. 1.
8B is an enlarged cross-sectional view of region P according to the exemplary embodiment of FIG. 1.
9 is a flowchart illustrating a method of processing a substrate by operating a substrate processing apparatus according to an exemplary embodiment of the present disclosure.
10 are graphs showing a comparison of changes in locations of high-density plasma regions according to the embodiments of FIGS. 4, 5B, 6B, 7A, and 8A.
11A, 11B, and 11C are simulation results showing a plasma density distribution according to the conventional substrate processing apparatus and the embodiments of FIGS. 4, 5B, 6B, 7A and 8A.
12A, 12B, 13A, 13B, 14A, and 14B are graphs showing the impedance phase of the substrate and the focus ring versus the high frequency power according to the thickness ratio of the upper layer and the lower layer of the focus ring in the substrate processing apparatus. Simulation results showing plasma density distribution are shown.

1 is a schematic cross-sectional view of a substrate processing apparatus according to an exemplary embodiment of the present disclosure. FIG. 2 is a perspective cross-sectional view illustrating a focus ring, a cover ring, a protruding electrode, and a fixing ring included in the substrate processing apparatus of FIG. 1. The same reference numerals in FIGS. 1 and 2 may refer to configurations corresponding to each other. The substrate processing apparatus 10 according to the embodiments of the present disclosure may process the substrate W using plasma. For example, the substrate processing apparatus 10 may be a capacitively coupled plasma (CCP) substrate processing apparatus capable of performing an etching process on the substrate W.

Referring to FIG. 1, the substrate processing apparatus 10 may include a process chamber 100, a support 200, and a plasma source unit 400. The substrate processing apparatus 10 may further include an exhaust unit 105, a power supply unit 300, and a gas supply unit 500.

The process chamber 100 may have an internal space. For example, the process chamber 100 may have a cylindrical shape. The process chamber 100 may include aluminum. The process chamber 100 may electrically have a ground potential.

An exhaust port 101 is formed at the bottom of the process chamber 100, and the exhaust port 101 may be connected to an exhaust part 105 installed below the process chamber 100 through an exhaust pipe 103. The exhaust unit 105 may include a vacuum pump such as a turbo pump to adjust the processing space inside the process chamber 100 to a pressure of a desired degree of vacuum. For example, reaction by-products and residual gases generated during the substrate processing process are exhausted to the outside through the exhaust port 101 and the exhaust pipe 103, and the exhaust unit 105 may adjust the pressure in the process chamber 100.

The support 200 may be disposed below the process chamber 100. The support 200 may support the substrate W. The support 200 may adsorb the substrate W using electrostatic force. In one embodiment, the support 200 may support the substrate W in the same manner as mechanical clamping. For example, the support 200 may be a susceptor for supporting the substrate W.

The support 200 may include an electrostatic chuck (ESC) 220 and a ring unit 230. The electrostatic chuck 220 may support the substrate W and the ring unit 230. The electrostatic chuck 220 may include a first circulation passage 220a through which a heat transfer medium circulates and a second circulation passage 220b through which a refrigerant circulates. The electrostatic chuck 220 may include a dielectric layer 221 and a lower electrode 225.

The dielectric layer 221 may be disposed on the lower electrode 225. The dielectric layer 221 may be a disk-shaped dielectric. The substrate W may be directly mounted on the upper surface of the dielectric layer 221. The upper surface of the dielectric layer 221 may face the lower surface of the plasma source unit 400. The dielectric layer 221 may have a diameter smaller than that of the substrate W. In the top view, the edge region of the substrate W may not overlap with the dielectric layer 221.

A dielectric layer 221 and a ring unit 230 may be disposed on the lower electrode 225. The lower electrode 225 may include a metallic material. For example, the lower electrode 225 may include aluminum. A power supply unit 300 including a high frequency power supply 310, a low frequency power supply 320, and a matching device 330 may be connected to the lower electrode 225. A high-frequency power supply 310 and a low-frequency power supply 320 may be provided to the lower electrode 225 through a matching device 330. The high frequency power supply 310 may provide power of a relatively high frequency to the lower electrode 225, and the low frequency power supply 320 may provide power of a relatively low frequency to the lower electrode 225. For example, the high frequency power supply 310 may provide power of 40 to 60 MHz, and the low frequency power supply 320 may provide power of 400 kHz. The lower electrode 225 provided with high frequency power may provide high frequency power to the processing space.

The ring unit 230 may be disposed on the electrostatic chuck 220. The ring unit 230 has a ring shape in a top view, and may surround an upper portion of the electrostatic chuck 220. For example, the ring unit 230 may surround the dielectric layer 221 and the substrate W on the dielectric layer 221. The ring unit 230 may be mounted on the lower electrode 225. The ring unit 230 may surround the upper portion of the lower electrode 225.

The plasma source unit 400 may be located above the process chamber 100. The plasma source unit 400 may be positioned on the support 200 to be spaced apart from the support 200. A processing space (plasma generation region) may be provided between the plasma source unit 400 and the electrostatic chuck 220. The plasma source unit 400 may generate plasma from a processing gas supplied into the process chamber 100.

1 and 2, the ring unit 230 may include a ring-shaped focus ring 231 and a cover ring 232. The focus ring 231 may have a diameter smaller than that of the cover ring 232. The focus ring 231 may be disposed on the electrostatic chuck 220 to surround an outer portion of the dielectric layer 221. The cover ring 232 may be disposed outside the focus ring 231 on the electrostatic chuck 220. The cover ring 232 may be disposed to surround the outer portion of the focus ring 231. The focus ring 231 may control the electromagnetic field so that the plasma density is uniformly distributed over the entire area of the substrate W. Accordingly, each region of the substrate W may be uniformly etched. The cover ring 232 may serve to support the focus ring 231.

The plasma source unit 400 may include a shower head 410 and a fixing ring 420. The shower head 410 is positioned above the process chamber 100 and may be disposed to face the electrostatic chuck 220 of the support 200. For example, the shower head 410 may include silicon (Si).

The shower head 410 may include an upper electrode 411 and an electrode support 415. The upper electrode 411 may be detachably coupled to the electrode support 415. The electrostatic chuck 220 may be positioned under the upper electrode 411. The upper electrode 411 may be positioned on the support 200 to face the lower electrode 225. The upper electrode 411 may be a circular electrode plate. Injection holes 411a penetrating in the thickness direction may be formed in the upper electrode 411. For example, the upper electrode 411 may include silicon (Si).

The electrode support 415 may be positioned on the upper electrode 411. The electrode support 415 may have a disk-shaped empty accommodation space RS therein. A plurality of through holes may be formed in the bottom of the electrode support 415. Each of the through holes may overlap the injection holes 411a of the upper electrode 411 in the top view. Accordingly, the receiving space RS and the processing space may communicate with each other through the through holes and the injection holes 411a. The electrode support 415 may include a water cooling structure to cool the shower head 410 to a desired temperature during plasma etching. A gas supply hole may be formed on the electrode support 415. For example, the electrode support 415 may be made of a conductive material.

The upper electrode 411 of the substrate processing apparatus 10 may include an inner electrode 412, an outer electrode 413, and a protruding electrode 414. The inner electrode 412 may have a disk shape. The inner electrode 412 may penetrate in the thickness direction to form injection holes 411a communicating with the through hole of the electrode support 415. The inner electrode 412 serves to generate plasma together with the lower electrode 225.

The outer electrode 413 has a ring shape and may be disposed to surround the inner electrode 412. The outer electrode 413 may electrically connect the inner electrode 412 and the protruding electrode 414. The outer electrode 413 may be placed on the fixing ring 420 to stably fix the upper electrode 411. In one embodiment, the outer electrode 413 is located inside the fixing ring 420 in the top view, and may not contact the fixing ring 420.

The protruding electrode 414 has a ring shape and may be located under the outer electrode 413. The protruding electrode 414 may be located inside the fixing ring 420. The protruding electrode 414 may serve to physically confine the generated plasma in the processing space.

The fixing ring 420 may be located at the upper corner of the process chamber 100. The fixing ring 420 may be located near the outside of the shower head 410. The fixing ring 420 may have a ring shape. The fixing ring 420 may have a larger diameter than the protruding electrode 414. In one embodiment, the fixing ring 420 may fix the shower head 410 to the upper portion of the process chamber 100. For example, the fixing ring 420 may support the outer electrode 413 under the outer electrode 413 of the upper electrode 411. For example, the fixing ring 420 may include quartz.

The gas supply unit 500 may be connected to the shower head 410. The gas supply unit 500 may include a gas supply pipe 510, a flow controller, and a gas supply source 530. The gas supply pipe 510 is connected to the receiving space RS through the gas supply hole of the electrode support 415, and the flow controller is the supply flow rate of the processing gas flowing into the process chamber 100 through the gas supply pipe 510 Can be controlled. For example, the gas supply source 530 may include a plurality of gas tanks, and the flow controller may include a plurality of mass flow controllers respectively corresponding to the gas tanks. The mass flow controllers can each independently control the supply flow rates of the process gases.

3 is a graph showing an etch rate according to an area of a substrate in a conventional substrate processing apparatus.

Referring to FIG. 3, it can be seen that in a conventional substrate processing apparatus, an etch rate is high in an edge region of a substrate (eg, near a radius of 150 mm). When high frequency power is applied to the support of a conventional substrate processing apparatus, the electrostatic chuck and the focus ring including different materials have an impedance difference with respect to the high frequency power. Depending on the impedance difference between the electrostatic chuck and the focus ring, the RF phase difference occurs in the processing space on the electrostatic chuck and the processing space on the focus ring. A high-density plasma region in which plasma is concentrated may be formed on the region. Accordingly, the etch rate may not be uniform on the substrate, and the etch rate may vary according to the position of the substrate as shown in FIG. 3.

In order to solve this problem, the present invention provides a substrate processing apparatus in which plasma density is uniform on a substrate by generating plasma to have a wider radius than a substrate so that a high-density plasma region is formed outside the edge region of the substrate. . For example, in the present invention, a skin depth approximately than a radius at which plasma is generated in a conventional substrate processing apparatus (for example, it may be a skin depth determined according to a frequency of high frequency power in the substrate processing apparatus). It is possible to provide a substrate processing apparatus capable of generating plasma in a wider radius range.

To this end, in the substrate processing apparatus as shown in FIG. 1, the present invention 1) physically diffuses plasma, or 2) reduces the impedance difference between the electrostatic chuck 220 and the focus ring 231 with respect to the high frequency power, and thus RF Embodiments capable of minimizing the phase difference are disclosed.

Specifically, the present invention relates to the shape, material, thickness, and/or focus ring 231 of the focus ring 231 capable of minimizing the impedance difference between the electrostatic chuck 220 and the focus ring 231 against high frequency power. The resistivity of and the thickness of the dielectric layer 221 of the electrostatic chuck 220 are disclosed. In the focus ring 231 and the dielectric layer 221 that can minimize the impedance difference disclosed in the present invention, the maximum potential value according to the phase difference of the RF with respect to the electrostatic chuck 220 and the focus ring 231 does not exceed the ionization threshold. It can have a configuration that does not.

Hereinafter, as described above, embodiments of the substrate processing apparatus of the present invention capable of generating plasma to have a larger radius than the substrate W will be described in detail.

4 is an enlarged cross-sectional view of region P according to the exemplary embodiment of FIG. 1. In FIGS. 1, 2, and 4, the same reference numerals denote the same components, and hereinafter, descriptions of contents overlapping with those described in FIGS. 1 and 2 will be omitted.

Referring to FIG. 4, the ring unit 230 may include a focus ring 231 and a cover ring 232. The focus ring 231 may be mounted on the upper surface of the electrostatic chuck 220. The focus ring 231 may be disposed on the lower electrode 225. The focus ring 231 may have a stepped upper portion. For example, when the substrate W is mounted on the support 200, the focus ring 231 is at a level lower than the first upper surface and the lower surface of the substrate W positioned at a higher level than the lower surface of the substrate W. It may include a second upper surface located at.

The cover ring 232 may be disposed outside the focus ring 231 on the electrostatic chuck 220. The cover ring 232 may have a ring shape having a larger radius than the focus ring 231. The cover ring 232 may include an overhang portion OH having a lower surface coplanar with the lower surface of the focus ring 231. The overhang part OH may cover a part of the upper surface of the lower electrode 225. For example, the cover ring 232 may include quartz.

In one embodiment, the focus ring 231 may include an upper layer 231a and a lower layer 231b. The upper layer 231a may be located on the lower layer 231b. For example, the upper layer 231a may include silicon (Si), and the lower layer 231b may include alumina (Al ₂ O ₃ ). In an embodiment, silicon (Si) of the upper layer 231a may be doped with impurities. The specific resistance of the focus ring 231 may vary depending on the material of the upper layer 231a, the material of the lower layer 231b, the type of impurities doped in the upper layer 231a, and/or the concentration of the impurities doped into the upper layer 231a. For example, the upper layer 231a of the focus ring 231 may be doped with impurities so that the focus ring 231 has a specific resistance of approximately 100 Ω·cm.

The ratio of the thickness of the upper layer 231a and the lower layer 231b may be 1 to 2: 3 (ie, the thickness of the lower layer is 0.25 to 0.4 times the total thickness of the focus ring 231 ). The specific resistance of the focus ring 231 may be approximately 100 Ω·cm. The dielectric layer 221 of the electrostatic chuck 220 may have a thickness of 1 to 4 mm. Preferably, the thickness of the dielectric layer 221 may be 3 to 4 mm. When the thickness of the dielectric layer 221 is 3 to 4 mm, the dielectric layer 221 may have excellent durability.

When the etching process is performed in the substrate processing apparatus 10 including the focus ring 231 and the dielectric layer 221 as described above, the difference in impedance for high frequency power between the electrostatic chuck 220 and the focus ring 231 is reduced. , RF phase difference can be reduced. As a result, the difference between the plasma density on the electrostatic chuck 220 and the plasma density on the focus ring 231 is reduced, and a high-density plasma region may be formed outside the edge region of the substrate W. Accordingly, an overall uniform plasma region may be formed on the substrate W.

In one embodiment, the upper electrode 411 of the shower head 410 may include an inner electrode 412 and an outer electrode 413. The lower surface of the outer electrode 413 may be exposed, and the upper electrode 411 may not include the protruding electrode 414. A portion of the lower surface of the outer electrode 413 may contact the upper surface of the fixing ring 420.

The fixing ring 420 may be extended inwardly to the top of the cover ring 232 in a wide width. The fixing ring 420 may overlap the upper surface of the cover ring 232 in a top view. The fixed ring 420 may have an inner diameter larger than the inner diameter of the cover ring 232 and smaller than the outer diameter of the cover ring 232. In one embodiment, the horizontal distance D between the first vertical line V1 aligned with the inner surface of the fixing ring 420 and the second vertical line V2 aligned with the inner surface of the cover ring 232 is the cover ring It is 3/4 or more of the width of the upper surface of the 232 and may be smaller than the width of the upper surface of the cover ring 232. When the protruding electrode 414 that prevents the diffusion of plasma and confines the plasma into the processing space is removed, the edge region of the substrate W and/or the high-density plasma region formed near the edge region of the substrate W are outward from the edge region of the substrate W. Can be formed further away. In addition, since the length in which the fixing ring 420 extends inward is limited, plasma diffusion is prevented by the fixing ring 420, so that a high-density plasma region is not formed in the edge region of the substrate W. In addition, the upper electrode 411 can be stably supported.

5A is an enlarged cross-sectional view of area P according to the exemplary embodiment of FIG. 1. 5B is an enlarged cross-sectional view of region P according to the exemplary embodiment of FIG. 1. In FIGS. 1, 2, 4, 5A, and 5B, the same reference numerals denote the same components, and descriptions of contents overlapping with those described in FIGS. 1, 2, and 4 will be omitted.

5A, the upper electrode 411 of the shower head 410 may include an inner electrode 412, an outer electrode 413, and a protruding electrode 414. The protruding electrode 414 may be coupled to the lower portion of the outer electrode 413. The protruding electrode 414 may be coupled to the outer electrode 413 to be detachable. In one embodiment, the protruding electrode 414 may be integrally formed with the outer electrode 413. The protruding electrode 414 may have a ring shape. The protruding electrode 414 may have an inner diameter substantially equal to or greater than the outer diameter of the inner electrode 412.

The protruding electrode 414 may include a first lower surface 414b having an inclination with respect to the upper surface 414a in contact with the lower surface of the outer electrode 413 and a second lower surface 414c parallel to the upper surface. The first lower surface 414b may be positioned adjacent to the inner electrode 412, and the second lower surface 414c may be positioned outside the first lower surface 414b. For example, the first lower surface 414b may have an inclination of 45° or less with respect to the upper surface 414a. Preferably, the first lower surface 414b may have an inclination of 20 to 25° with respect to the upper surface 414a. The protruding electrode 414 may include the same material as the inner electrode 412. For example, the protrusion electrode 414 may include silicon (Si).

The ring unit 230 may include a focus ring 231 having an expanded width and a cover ring 232 having a reduced width. In an embodiment, the horizontal width Wf of the upper surface of the focus ring 231 may be 2 to 10 times the horizontal width Wc of the first upper surface 232a of the cover ring 232. As the width of the focus ring 231 that concentrates the plasma into the processing region is widened, the diffusion of plasma is increased, and thus, a high-density plasma region may be formed outside the edge region of the substrate W.

As shown in FIG. 4, the focus ring 231 may include an upper layer 231a including silicon (Si) and a lower layer 231b including alumina (Al ₂ O ₃ ). The ratio of the thickness of the upper layer 231a and the lower layer 231b may be 1 to 2: 3 (ie, the thickness of the lower layer is 0.25 to 0.4 times the thickness of the focus ring 231 ). The specific resistance of the focus ring 231 may be approximately 100 Ω·cm. The dielectric layer 221 of the electrostatic chuck 220 may have a thickness of approximately 3 to 4 mm.

Referring to FIG. 5B, in one embodiment, when the horizontal width Wf of the upper surface of the focus ring 231 is 2 to 10 times the horizontal width Wc of the first upper surface 232a of the cover ring 232 A portion of the focus ring 231 (inner portion) may be disposed on the lower electrode 225 and the remaining portion (outer portion) of the focus ring 231 may be disposed on the cover ring 232. The cover ring 232 may have a first upper surface 232a and a second upper surface 232b having a step difference, and the first upper surface 232a may be positioned at a higher level than the second upper surface 232b. The first upper surface 232a may be located inside the second upper surface 232b. The outer portion of the focus ring 231 may be placed on the second upper surface 232b.

6A is an enlarged cross-sectional view of region P according to the exemplary embodiment of FIG. 1. 6B is an enlarged cross-sectional view of region P according to the exemplary embodiment of FIG. 1. In FIGS. 1, 2 and 4 to 6B, the same reference numerals denote the same components, and hereinafter, descriptions of contents overlapping with those described in FIGS. 1, 2 and 4 to 5B will be omitted.

Referring to FIG. 6A, the dielectric layer 221 of the electrostatic chuck 220, the focus ring 231 of the ring unit 230, and the cover ring 232 may have the same configuration as that of FIG. 5A. For example, the horizontal width Wf of the upper surface of the focus ring 231 may be 2 to 10 times the horizontal width Wc of the upper surface of the cover ring 232.

The upper electrode 411 of the shower head 410 may include an inner electrode 412 and an outer electrode 413. In contrast to FIG. 5A, the upper electrode 411 does not include the protruding electrode 414, and at least a portion of the lower surface of the outer electrode 413 may be exposed.

The fixing ring 420 positioned below the outer electrode 413 has a relatively wider width than the fixing ring 420 of FIG. 5A, and may extend inward to the top of the cover ring 232. In one embodiment, the inner diameter of the fixing ring 420 may be larger than the inner diameter of the cover ring 232 and smaller than the outer diameter of the cover ring 232. In one embodiment, the horizontal distance D between the first vertical line V1 aligned with the inner surface of the fixing ring 420 and the second vertical line V2 aligned with the inner surface of the cover ring 232 is the cover ring It is 3/4 or more of the horizontal width Wc of the upper surface of the 232 and may be smaller than the horizontal width Wc of the upper surface of the cover ring 232.

6B, the dielectric layer 221 of the electrostatic chuck 220, the focus ring 231 and the cover ring 232 of the ring unit 230, and the upper electrode 411 of the shower head 410 are shown in FIG. 5B. It can have the same configuration. For example, the horizontal width Wf of the upper surface of the focus ring 231 is 2 to 10 times the horizontal width Wc of the first upper surface 232a of the cover ring 232, and the outer portion of the focus ring 231 It may be located on the second upper surface 232b of the cover ring 232.

The upper electrode 411 of the shower head 410 may include an inner electrode 412 and an outer electrode 413. The upper electrode 411 does not include the protruding electrode 414, and a portion of the lower surface of the outer electrode 413 may be exposed. The fixing ring 420 may be disposed to overlap the cover ring 232 in the top view. For example, the first vertical line V1 aligned with the inner surface of the fixing ring 420 may pass through the first upper surface 232a or the second upper surface 232b of the cover ring 232.

When the etching process is performed in the substrate processing apparatus 10 having the configurations of FIGS. 5A, 5B, 6A, and 6B, compared to the conventional substrate processing apparatus, the thickness of the dielectric layer 221 and the focus ring 231 are Depending on the specific resistance, the difference in impedance with respect to the high frequency power is reduced, the RF phase difference is reduced, and the plasma concentration phenomenon caused by the extended focus ring 231 may be reduced.

As shown in FIGS. 6A and 6B, when the protruding electrode 414 that prevents the diffusion of plasma and confines the plasma into the processing space is removed, diffusion of the plasma may be facilitated. Accordingly, the high-density plasma region formed in the edge region of the substrate W may be formed outside the edge region of the substrate W. In addition, since the length in which the fixing ring 420 extends inward is limited, plasma diffusion is suppressed by the fixing ring 420 to prevent formation of a high-density plasma region in the edge region of the substrate W. In addition, while the fixing ring 420 stably supports the upper electrode 411 of the shower head 410, the high-density plasma region may be formed outside the edge region.

7A is an enlarged cross-sectional view of area P according to the exemplary embodiment of FIG. 1. 7B is an enlarged cross-sectional view of region P according to the exemplary embodiment of FIG. 1. In FIGS. 1, 2, and 4 to 7B, the same reference numerals denote the same components, and hereinafter, descriptions of contents overlapping with those described in FIGS. 1 to 6B will be omitted.

Referring to FIG. 7A, the dielectric layer 221 may have a thickness of 3 to 4 mm. The focus ring 231 may include an upper layer 231a including silicon (Si) and a lower layer 231b including alumina (Al ₂ O ₃ ). In an embodiment, silicon (Si) of the upper layer 231a may be doped with impurities. The ratio of the thickness of the upper layer 231a and the lower layer 231b may be 1 to 2: 3 (ie, the thickness of the lower layer is 0.25 to 0.4 times the thickness of the focus ring 231 ). The upper electrode 411 of the shower head 410 may include an inner electrode 412, an outer electrode 413, and a protruding electrode 414.

In one embodiment, the upper layer 231a of the focus ring 231 may be formed with a recess R having a predetermined width and a predetermined depth from an upper surface along the circumferential direction of the focus ring 231. The volume of the recess R may be 0.4 to 4 times the volume of the focus ring 231. That is, the volume of the recess R may be 20% to 80% of the volume of the focus ring 231 before the recess R is formed (for example, the volume of the focus ring 231 in FIG. 4 ). have. In FIG. 7A, the cross section of the recess R is shown in a square shape, but the present invention is not limited thereto, and the recess R has various shapes in which the upper layer 231a of the focus ring 231 is recessed downward. Can have When the recess R is formed in the focus ring 231, the impedance with respect to the frequency of the high frequency power is reduced in the plasma etching process, and the high-density plasma region may move outward from the edge region of the substrate W.

Referring to FIG. 7B, the recess R of the focus ring 231 may also be formed in the focus ring 231 having an extended width. The substrate processing apparatus of FIG. 7B includes a configuration corresponding to that of FIG. 7A, wherein the horizontal width Wf of the upper surface of the focus ring 231 in which the recess R is formed is the horizontal width Wc of the upper surface of the cover ring 232. ) Can be 2 to 10 times. The volume of the recess R may be 0.4 to 4 times the volume of the focus ring 231. That is, the volume of the recess R may be 20% to 80% of the volume of the focus ring 231 before the recess R is formed (for example, the volume of the focus ring 231 in FIG. 5A ). have. The substrate processing apparatus including the focus ring 231 having a recess R formed and an extended width as shown in FIG. 7B has a higher density plasma region in the edge region of the substrate W than the substrate processing apparatus of FIG. 7A. Can move farther outward.

8A is an enlarged cross-sectional view of region P according to the exemplary embodiment of FIG. 1. 8B is an enlarged cross-sectional view of region P according to the exemplary embodiment of FIG. 1. In FIGS. 1, 2, and 4 to 8B, the same reference numerals denote the same components, and hereinafter, descriptions of contents overlapping with those described in FIGS. 1 to 7B will be omitted.

Referring to FIG. 8A, the dielectric layer 221 of the electrostatic chuck 220, the focus ring 231 and the cover ring 232 of the ring unit 230, the inner electrode 412 and the outer electrode of the upper electrode 411 ( 413) may be the same as the configurations of FIG. 7A.

In FIG. 8A, compared to FIG. 7A, the upper electrode 411 does not include the protruding electrode 414, and the fixing ring 420 may have a relatively expanded width. The fixing ring 420 and the cover ring 232 may overlap in the same manner as described in FIG. 4. Since the upper electrode 411 does not include the protruding electrode 414, diffusion of the plasma is increased, so that the high-density plasma region may move farther outward than the edge region of the substrate W. Accordingly, the edge region of the substrate W may have a uniform etch rate with other regions.

Referring to FIG. 8B, in the substrate processing apparatus, the dielectric layer 221 of the electrostatic chuck 220, the focus ring 231, and the cover ring 232 of the ring unit 230 may be the same as those of FIG. 7B. That is, a recess (R) is formed in the focus ring 231, and the horizontal width (Wf) of the upper surface of the focus ring 231 is 2 to 10 times the horizontal width (Wc) of the upper surface of the cover ring 232 I can. The volume of the recess R may be 0.4 to 4 times the volume of the focus ring 231. In FIG. 8B, compared to FIG. 7B, the upper electrode 411 does not include the protruding electrode 414, and the first vertical line V1 aligned with the inner surface of the fixing ring 420 and the inner surface of the cover ring 232 The horizontal distance D of the second vertical line V2 aligned to is 3/4 or more of the width of the top surface of the cover ring 232 and may be smaller than the width of the top surface of the cover ring 232. Accordingly, diffusion of the plasma is increased, so that the high-density plasma region may move farther outward than the edge region of the substrate W. Accordingly, the edge region of the substrate W may have a uniform etch rate with other regions.

9 is a flowchart illustrating a method of processing a substrate by operating a substrate processing apparatus according to an exemplary embodiment of the present disclosure.

1 and 9, in the substrate processing method according to an embodiment of the present disclosure, the substrate W is loaded on the electrostatic chuck 220 in the process chamber 100 (S100), and the process chamber 100 Supplying a processing gas to the inside (S120), providing an RF signal to the lower electrode 225 (S130), and processing the substrate (W) (S140).

Loading the substrate W onto the electrostatic chuck 220 in the process chamber 100 (S100) is to introduce the substrate W to be processed from the outside through the gate 14 into the process chamber 100 , Mounting the substrate W on the electrostatic chuck 220 of the support 200 and adsorbing the substrate W onto the dielectric layer 221 of the electrostatic chuck 220.

Supplying the processing gas into the process chamber 100 (S120) is to supply the processing gas from the gas supply unit 500 to the receiving space RS of the shower head 410, and the processing gas is injected by the shower head 410 It may include passing through the holes 411a and being distributed in a shower shape in the process chamber 100 to be supplied to the processing space in the process chamber 100.

Providing the RF signal to the lower electrode 225 (S130) is to provide RF power to the lower electrode 225 from the power supply 300 to excite the processing gas in a plasma state, and the substrate (W) and/or It may include selectively etching the etching target layer on the substrate W. The RF signal may include high frequency power provided from the high frequency power supply 310 and low frequency power provided from the low frequency power supply 320. In an embodiment, the high-frequency power supply 310 of the power supply unit may generate a capacitively coupled plasma in the process chamber 100. The low frequency power supply 320 may induce the generated capacitively coupled plasma to the substrate W. For example, the high frequency power supply 310 of the power supply unit may provide high frequency power of 40 to 60 MHz to the electrostatic chuck 220. Simultaneously with the high frequency power supply 310, the low frequency power supply 320 may apply a low frequency power of 400 kHz to the electrostatic chuck 220.

Processing the substrate W (S140) may include etching an etching target layer on the substrate W using plasma. The processing gas excited by the plasma by the high frequency power can be accelerated to the surface of the substrate W by the low frequency power and can react with the substrate W.

The etching process of the substrate W is completed, and residual gas in the processing space may be discharged to the outside of the process chamber 100 through the exhaust hole. Residual gases may include reaction by-products. The substrate W may be separated from the electrostatic chuck 220 and the substrate W may be recovered from the process chamber 100.

10 are graphs showing a comparison of changes in locations of high-density plasma regions according to the embodiments of FIGS. 4, 5B, 6B, 7A, and 8A. 11A, 11B, and 11C are simulation results showing a plasma density distribution according to the conventional substrate processing apparatus and the embodiments of FIGS. 4, 5B, 6B, 7A and 8A.

Reference of FIG. 10 and Reference of FIG. 11A show plasma density distributions of a conventional substrate processing apparatus. 10(a) and 11a(1) show the plasma density distribution of the substrate processing apparatus of FIG. 4, and FIG. 10(b) and FIG. 11b(2) show the plasma density distribution of the substrate processing apparatus of FIG. 5b. Fig. 10(c) and Fig. 11b(3) show the plasma density distribution of the substrate processing apparatus of Fig. 6b, and Figs. 10(d) and 11c(4) are shown in Fig. 7a. The plasma density distribution of the substrate processing apparatus of Fig. 10E and Fig. 11C (5) show the plasma density distribution of the substrate processing apparatus of Fig. 8A.

1, 4 to 8B, 10, and 11A to 11C, 1) no protruding electrode 414 2) an extended width of the focus ring 231, 3) a focus ring 231 ) In the case where the recess R is formed along the circumferential direction of the focus ring 231, or 4) the dielectric has a thickness of 4 mm or less, and the focus ring 231 is an upper layer 231a of silicon (Si) ) And a lower layer 231b of alumina (Al ₂ O ₃ ), and a substrate processing apparatus comprising at least one of the cases in which the ratio of the thickness of the upper layer 231a and the lower layer 231b is 1 to 2: 3 ( 10), it can be seen that the central axis of the high-density plasma region formed in the edge region of the substrate W deviates from the substrate edge region to the outside of the substrate W.

When the substrate processing apparatus 10 has a configuration of 1) or 2), the degree of diffusion of the plasma is increased to increase the plasma generation radius, and accordingly, the location of the high-density plasma is also wider than that of the edge area of the substrate (W). It can be formed in a radius.

When the substrate processing apparatus 10 has a configuration of 3) or 4), the impedance difference between the dielectric layer 221 on the electrostatic chuck 220 and the focus ring 231 for high frequency power is reduced, and the RF phase difference is minimized. can do. Accordingly, it is possible to reduce a phenomenon in which the plasma density increases in the edge region of the substrate W according to the RF phase difference.

12A, 12B, 13A, 13B, 14A, and 14B are graphs showing the impedance phase of the substrate and the focus ring versus the high frequency power according to the thickness ratio of the upper layer and the lower layer of the focus ring in the substrate processing apparatus. Simulation results showing plasma density distribution are shown.

In the substrate processing apparatus according to the embodiments of the present disclosure, the ratio of the thickness of the upper layer including silicon (Si) of the focus ring and the lower layer including alumina (Al ₂ O ₃ ) is 1 to 2: 3 (that is, the thickness of the lower layer Is 0.25 to 0.4 times the total thickness of the focus ring 231). In this case, the specific resistance of the focus ring may have approximately 100 Ω·cm. When the ratio of the thickness of the upper layer and the lower layer is 1 to 2: 3 and the specific resistance of the focus ring is approximately 100 Ω·cm, the impedance phase difference between the substrate and the focus ring against high frequency power is minimized. It is not dense, and a uniform etch rate may appear over the entire area of the substrate, which can be confirmed through FIGS. 12A to 14B.

Specifically, in the substrate processing apparatus showing the results of FIGS. 12A and 12B, the specific resistance of the focus ring is 100 Ω·cm, the thickness of the upper layer including silicon (Si) of the focus ring is 3 mm, and the lower layer including alumina (Al 2 O 3 ). The thickness is 1mm. In the substrate processing apparatus showing the results of FIGS. 13A and 13B, the specific resistance of the focus ring is 100 Ω·cm, the thickness of the upper layer including silicon (Si) of the focus ring is 3 mm, and the thickness of the lower layer including alumina (Al2O3) is 2 mm. to be. In the substrate processing apparatus showing the results of FIGS. 14A and 14B, the thickness of the upper layer including silicon (Si) of the focus ring is 4 mm, and the thickness of the lower layer including alumina (Al 2 O 3) is 1 mm. In FIGS. 12A and 13A, the phase difference between the substrate and the focus ring for high frequency power is relatively small compared to FIG. 14A. Accordingly, the simulation results of FIGS. 12B and 13B show a relatively uniform plasma density than the simulation results of FIG. 14B. It can be seen that it has a distribution.

In the above, embodiments according to the technical idea of the present invention have been described with reference to the accompanying drawings, but those of ordinary skill in the technical field to which the present invention pertains, the present invention does not change the technical idea or essential features of the present invention. It will be appreciated that it can be implemented with. It is to be understood that the embodiments described above are illustrative in all respects and not limiting.

10: substrate processing apparatus 100: process chamber
101: exhaust port 103: exhaust pipe
105: exhaust part 200: support
220: electrostatic chuck 220a: first circulation flow path
220b: second circulation passage 221: dielectric layer
225: lower electrode 230: ring unit
231: focus ring 231a: upper layer
231b: lower layer R: recess
232: cover ring 232a: first upper surface
232b: second upper surface 300: power supply
310: high frequency power supply 320: high frequency power supply
330: matcher 400: plasma source unit
410: shower head 411: upper electrode
411a: injection hole 412: inner electrode
413: outer electrode 414: protruding electrode
415: electrode support 420: fixing ring
500: gas supply unit 510: gas supply pipe
520: flow controller 530: gas source

Claims (20)

Process chamber;
A shower head positioned above the process chamber;
A fixing ring positioned at the upper portion of the process chamber and near the outer side of the shower head;
Including a support disposed below the process chamber,
The shower head,
Including an upper electrode on the support,
The support,
An electrostatic chuck disposed under the upper electrode; And
And a ring unit disposed on the electrostatic chuck,
The electrostatic chuck,
A lower electrode on which the ring unit is seated; And
Including a dielectric layer disposed on the lower electrode,
The ring unit,
A focus ring surrounding an outer portion of the dielectric layer; And
It includes a cover ring disposed outside the focus ring,
The focus ring,
Including a lower layer containing Al ₂ O ₃ and an upper layer containing Si on the lower layer,
The thickness of the dielectric layer is 3 to 4 mm or less,
The thickness of the lower layer of the focus ring is 0.25 to 0.4 times the thickness of the focus ring,
The fixing ring overlaps a part of the cover ring in a top view, but a vertical line aligned with the inner surface of the fixing ring is spaced apart from a vertical line perpendicular to the inner surface of the cover ring by a predetermined distance, and the predetermined distance is the A capacitively coupled plasma substrate processing apparatus that is larger than 3/4 times the width of the upper surface of the cover ring and smaller than the width of the upper surface of the cover ring. The method of claim 1,
The fixing ring,
Has an inner diameter larger than the inner diameter of the cover ring,
The cover ring,
A capacitively coupled plasma substrate processing apparatus comprising an overhang portion having a lower surface coplanar with the lower surface of the focus ring. The method of claim 1,
The specific resistance of the focus ring is 100 Ω·cm. The method of claim 1,
The focus ring,
A capacitively coupled plasma substrate processing apparatus including Si doped with impurities. The method of claim 1,
The focus ring,
A capacitively coupled plasma substrate processing apparatus in which the horizontal width of the upper surface is 2 to 10 times the horizontal width of the upper surface of the cover ring. The method of claim 5,
The cover ring,
It has a first upper surface and a second upper surface having a step, the first upper surface is located at a level higher than the second upper surface,
The focus ring covers the second upper surface of the capacitively coupled plasma substrate processing apparatus. The method of claim 1,
The focus ring,
A capacitively coupled plasma substrate processing apparatus further comprising a concave recess. The method of claim 7,
The volume of the recess is 20 to 80% of the volume of the focus ring capacitively coupled plasma substrate processing apparatus. The method of claim 1,
The upper electrode,
An inner electrode having a spray hole penetrating through the thickness direction; And
Capacitively coupled plasma substrate processing apparatus comprising an outer electrode surrounding the inner electrode. The method of claim 9,
The outer electrode,
A capacitively coupled plasma substrate processing apparatus in which the portion of the fixing ring is in contact with an upper surface of the fixed ring. The method of claim 9,
The upper electrode,
A capacitively coupled plasma substrate processing apparatus further comprising a protruding electrode coupled to a lower portion of the outer electrode. The method of claim 1,
The cover ring and the fixing ring include quartz,
The upper electrode is a capacitively coupled plasma substrate processing apparatus including silicon (Si). Process chamber;
A shower head positioned above the process chamber;
A fixing ring located near the outside of the shower head;
It includes a support located under the shower head,
The shower head,
Including an upper electrode formed with a spray hole,
The support,
It includes an electrostatic chuck and a ring unit disposed on the electrostatic chuck,
The electrostatic chuck,
Including a lower electrode and a dielectric layer on the lower electrode,
The ring unit,
A focus ring disposed outside the lower electrode; And
And a cover ring disposed outside the focus ring on the lower electrode,
The focus ring,
The width of the upper surface is 2 to 10 times the width of the upper surface of the cover ring,
The fixing ring overlaps a part of the cover ring in the top view, but a vertical line aligned with the inner surface of the fixing ring is spaced apart from a vertical line perpendicular to the inner surface of the cover ring by a predetermined distance, and the predetermined distance is the A capacitively coupled plasma substrate processing apparatus that is larger than 3/4 times the width of the upper surface of the cover ring and smaller than the width of the upper surface of the cover ring. The method of claim 13,
The focus ring,
A capacitively coupled plasma substrate processing apparatus comprising a lower layer containing Al ₂ O ₃ and an upper layer containing Si on the lower layer. The method of claim 14,
The thickness of the dielectric layer is 3 to 4 mm,
The focus ring has a specific resistance of 100 Ω·cm,
The lower layer is a capacitively coupled plasma substrate processing apparatus having a thickness of 0.25 to 0.4 times the thickness of the focus ring. The method of claim 13,
The focus ring,
A capacitively coupled plasma substrate processing apparatus including Si doped with impurities. The method of claim 13,
The focus ring,
A capacitively coupled plasma substrate processing apparatus further comprising a concave recess. The method of claim 17,
The volume of the recess is 20 to 80% of the volume of the focus ring capacitively coupled plasma substrate processing apparatus. Loading a substrate onto an electrostatic chuck disposed in a process chamber included in the substrate processing apparatus;
Supplying a processing gas onto the substrate in the process chamber;
Generating plasma by providing an RF signal to the electrostatic chuck; And
Including processing the substrate using the plasma,
The substrate processing apparatus,
A ring unit disposed on the electrostatic chuck, a shower head disposed on the electrostatic chuck and the ring unit, and a fixing ring disposed at an upper corner of the process chamber,
The electrostatic chuck,
A lower electrode to which the RF signal is provided and a dielectric layer on the lower electrode,
The ring unit,
A focus ring adjacent to the substrate and a cover ring disposed outside the focus ring,
The thickness of the dielectric layer is 3 to 4 mm or less,
The focus ring includes an upper layer including Si and a lower layer including Al ₂ O ₃ ,
The upper layer comprises a concave recess,
A vertical line aligned with the inner surface of the fixing ring is spaced apart from a vertical line perpendicular to the inner surface of the cover ring by a predetermined distance,
The predetermined distance is greater than 3/4 of the width of the upper surface of the cover ring and smaller than the width of the upper surface of the cover ring, a substrate processing method using a capacitively coupled plasma substrate processing apparatus. The method of claim 19,
The volume of the concave recess is,
A substrate processing method using a capacitively coupled plasma substrate processing apparatus, which is 20% to 80% of the volume of the focus ring.

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