JP2023115472A - Plasma processing apparatus - Google Patents

Abstract

To provide a plasma processing apparatus that can control residence time of a gas introduced into a chamber.SOLUTION: A plasma processing apparatus that is disclosed comprises: a chamber; and a substrate support part. The chamber provides a processing space to an inside of the chamber. The substrate support part is provided in the chamber. The chamber has a side wall and a top part. The side wall extends in a side direction of the processing space to surround the processing space. The top part extends in an upward direction of the substrate support part. The top part includes an upper electrode. The upper electrode provides a plurality of gas holes and a plurality of grooves. The plurality of gas holes are opened toward the processing space to introduce a gas into the processing space. The plurality of grooves are opened toward the processing space. The plurality of grooves include two or more grooves having different cross-sectional shapes to each other.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to plasma processing apparatuses.

Plasma processing apparatuses are used in plasma processing of substrates. Patent Document 1 below describes a kind of plasma processing apparatus. A plasma processing apparatus described in Patent Document 1 includes a chamber, a substrate support, a showerhead, a dielectric window, and a VHF source. The chamber provides a processing space within it. A substrate support is provided within the chamber. The showerhead is provided above the substrate support. A showerhead introduces gas into the chamber. Gas introduced into the chamber forms a gas stream within the chamber. A dielectric window is interposed between the showerhead and the chamber to surround the showerhead. The VHF source generates electromagnetic waves in the VHF waveband. Electromagnetic waves from a VHF source are introduced into the chamber through the dielectric window. Plasma is generated from gas within the chamber by electromagnetic waves introduced into the chamber.

Japanese Patent Application Laid-Open No. 2020-53245

The present disclosure provides a plasma processing apparatus capable of controlling residence time of gas introduced into the chamber.

In one exemplary embodiment, a plasma processing apparatus is provided. A plasma processing apparatus includes a chamber and a substrate support. The chamber provides a processing space within it. A substrate support is provided within the chamber. The chamber has side walls and a top. A sidewall extends laterally of the processing space to surround the processing space. The top extends above the substrate support. The top includes an upper electrode. The top electrode provides a plurality of gas holes and a plurality of grooves. A plurality of gas holes open toward the processing space to introduce gas into the processing space. A plurality of grooves open toward the processing space. The plurality of grooves includes two or more grooves having cross-sectional shapes different from each other.

According to one exemplary embodiment, it is possible to control the residence time of the gas introduced into the chamber.

1 is a schematic cross-sectional view of a plasma processing apparatus according to one exemplary embodiment; FIG. FIG. 4 is an enlarged cross-sectional view of a top electrode according to one exemplary embodiment; 2 is an enlarged view of an upper electrode of a plasma processing apparatus according to one exemplary embodiment, viewed from below; FIG.

Various exemplary embodiments are described below.

In one exemplary embodiment, a plasma processing apparatus is provided. A plasma processing apparatus includes a chamber and a substrate support. The chamber provides a processing space within it. A substrate support is provided within the chamber. The chamber has side walls and a top. A sidewall extends laterally of the processing space to surround the processing space. The top extends above the substrate support. The top includes an upper electrode. The top electrode provides a plurality of gas holes and a plurality of grooves. A plurality of gas holes open toward the processing space to introduce gas into the processing space. A plurality of grooves open toward the processing space. The plurality of grooves includes two or more grooves having cross-sectional shapes different from each other.

In the above embodiments, gas introduced into the processing space through the plurality of gas holes forms a gas flow within the chamber. The gas that forms the gas stream resides in a plurality of grooves provided by the upper electrode. Since two or more of the plurality of grooves have cross-sectional shapes different from each other, the residence time of the gas in each of the plurality of grooves is adjusted according to the cross-sectional shape of each groove. Therefore, according to the above embodiment, it is possible to control the residence time of the gas introduced into the chamber.

In one exemplary embodiment, the plurality of gas holes may not include gas holes that open toward the plurality of grooves. A plurality of gas holes may be opened in a region where a plurality of grooves are not formed on the lower surface of the upper electrode. In this embodiment, gas is not introduced directly into the plurality of grooves. A relatively long residence time of the gas in the plurality of grooves is thus ensured.

In one exemplary embodiment, each of the plurality of grooves may have a unique ratio of its depth to its width. Each of the two or more grooves may have a ratio that differs from the ratio of other grooves of the two or more grooves.

In one exemplary embodiment, the two or more grooves may include a first groove and a second groove. The width of the first groove may be greater than the depth of the first groove. The width of the second groove may be smaller than the depth of the second groove. In this embodiment, the residence time of the gas staying in the second groove is longer than the residence time of the gas staying in the first groove.

In one exemplary embodiment, the plurality of grooves may have an annular shape. The plurality of grooves may extend circumferentially with respect to the central axis of the upper electrode. The number of grooves may be five or more. The plurality of grooves may be arranged along the radial direction perpendicular to the central axis. According to this embodiment, it is possible to control the residence time of the gas in the radial direction so as to obtain a desired density distribution of the active species in the radial direction.

In one exemplary embodiment, the radial pitch of the gas holes may be the same as the radial pitch of the grooves.

In one exemplary embodiment, the width of each of the plurality of grooves may be 1/2 or more of the pitch of the plurality of gas holes in the radial direction.

In one exemplary embodiment, the depth distribution of the plurality of grooves in the radial direction perpendicular to the central axis may be stepped. According to this embodiment, the residence time of the gas in the radial direction can be controlled step by step so as to obtain a desired density distribution of the active species in the radial direction.

In one exemplary embodiment, the area of the open ends of the plurality of grooves may be larger than the area of the region where the plurality of grooves are not formed on the lower surface of the upper electrode.

In one exemplary embodiment, the sidewalls of the chamber may provide one or more grooves opening into the processing space. The one or more grooves may have an annular shape and extend circumferentially about the central axis of the sidewall. In this embodiment, gas resides in one or more grooves formed in the sidewalls. Therefore, according to this embodiment, it is possible to increase the density of active species in the vicinity of the sidewall by increasing the residence time of the gas in the vicinity of the sidewall.

In one exemplary embodiment, the plasma processing apparatus may further comprise an inlet for propagating electromagnetic waves, which are VHF waves or UHF waves, to generate plasma in the processing space. A high-frequency electromagnetic wave in the VHF band or UHF band can generate a standing wave directly below the upper electrode. In this embodiment, it is possible to control the residence time of the gas so as to obtain a desired density distribution of the active species even in the presence of standing waves.

Various exemplary embodiments are described in detail below with reference to the drawings. In addition, suppose that the same code|symbol is attached|subjected to the part which is the same or equivalent in each drawing.

FIG. 1 is a schematic diagram of a plasma processing apparatus according to one exemplary embodiment. A plasma processing apparatus 1 shown in FIG. 1 is a parallel plate type plasma processing apparatus. The plasma processing apparatus 1 is configured to generate plasma using electromagnetic waves. A plasma processing apparatus 1 includes a chamber 10 and a substrate support 11 .

Chamber 10 has a generally cylindrical shape. The chamber 10 provides a processing space S within it. The chamber 10 extends along the vertical direction. The center axis of the chamber 10 is the center axis AX extending in the vertical direction. The chamber 10 is made of metal such as aluminum or an aluminum alloy, for example. A corrosion-resistant film may be formed on the surface of the chamber 10 on the processing space S side. Chamber 10 is grounded.

A substrate support 11 is provided within the chamber 10 . The substrate support part 11 is arranged in the processing space S. As shown in FIG. The substrate support part 11 is configured to substantially horizontally support the substrate W placed on its upper surface. The substrate support portion 11 has a substantially disk shape. In one embodiment, the central axis of the substrate support 11 is the central axis AX. A substrate W placed on the substrate support 11 is processed in the processing space S. As shown in FIG. The bottom of chamber 10 provides an exhaust port 12 . An exhaust device is connected to the exhaust port 12 .

Chamber 10 has side walls 20 and a top 30 . Side wall 20 has, for example, a substantially cylindrical shape. The sidewall 20 extends laterally of the processing space S so as to surround the processing space S. As shown in FIG. In one embodiment, the central axis of sidewall 20 is central axis AX. Side wall 20 may have a cylindrical shape. The sidewalls 20 are made of metal such as aluminum or an aluminum alloy, for example.

The top portion 30 extends above the substrate support portion 11 . The top portion 30 closes the upper end opening of the side wall 20 . The top portion 30 includes an upper electrode 40 . The top portion 30 may further include a cover 31 . The upper electrode 40 has a substantially disk shape. In one embodiment, the center axis of the upper electrode 40 is the center axis AX. The upper electrode 40 is made of metal such as aluminum or an aluminum alloy. The cover 31 covers the upper electrode 40 and partially extends above the upper electrode 40 . The cover 31 is made of metal such as aluminum or an aluminum alloy, for example. The cover 31 forms an electromagnetic wave waveguide between the upper electrode 40 and the cover 31 .

FIG. 2 will be referred to together with FIG. 1 below. FIG. 2 is an enlarged cross-sectional view of a top electrode according to one exemplary embodiment. Top electrode 40 provides a plurality of gas holes 41 and gas diffusion chambers 42 . A plurality of gas holes 41 are open toward the processing space S to introduce gas into the processing space S. As shown in FIG. A gas diffusion chamber 42 is provided inside the upper electrode 40 . A plurality of gas holes 41 are connected to the gas diffusion chamber 42 and extend downward from the gas diffusion chamber 42 .

Top electrode 40 provides a plurality of grooves 43 . The plurality of grooves 43 are open toward the processing space S. The multiple grooves 43 include two or more grooves having cross-sectional shapes different from each other. “Cross-sectional shape” means the shape of the groove in a cross section perpendicular to the direction in which the groove extends. As shown in FIG. 2, in one embodiment, the cross-sectional shapes of the plurality of grooves 43 may be different rectangular shapes. Moreover, "including two or more grooves having cross-sectional shapes different from each other" means that there is always another groove 43 having a cross-sectional shape different from that of one groove 43 .

In one embodiment, the plurality of gas holes 41 of the upper electrode 40 may not include gas holes that open toward the plurality of grooves 43 . As shown in FIG. 2, the plurality of gas holes 41 may open in a region 40c on the lower surface of the upper electrode 40 where the plurality of grooves 43 are not formed. For example, the region 40 c is positioned between two adjacent grooves among the plurality of grooves 43 on the lower surface of the upper electrode 40 .

In one embodiment, each of the plurality of grooves 43 has a unique ratio of its depth to its width. "Width" means the distance from one end to the other end of the open end of the groove in a cross section perpendicular to the direction in which the groove extends. "Depth" means the distance between the open end of the groove and the deep end of the groove. In one embodiment, two or more grooves having different cross-sectional shapes among the plurality of grooves 43 have different specific ratios. As shown in FIG. 2, for example, among the plurality of grooves 43, the groove 43a has a width W1 and a depth D1. Further, among the plurality of grooves 43, the groove 43b has a width W2 and a depth D2. The ratio D1/W1 of the groove 43a and the ratio D2/W2 of the groove 43b are different from each other.

In one embodiment, two or more grooves having different cross-sectional shapes among the plurality of grooves 43 include a first groove and a second groove. The width of the first groove may be greater than the depth of the first groove, and the width of the second groove may be less than the depth of the second groove. In the example shown in FIG. 2, the width W1 of the groove 43a is greater than the depth D1 of the groove 43a. That is, the ratio D1/W1 is less than one. Also, the width W2 of the groove 43b is smaller than the depth D2 of the groove 43b. That is, the ratio D2/W2 is greater than one.

In one embodiment, the distribution of depths of the plurality of grooves 43 in the radial direction perpendicular to the central axis AX of the upper electrode 40 may change stepwise. For example, as shown in FIG. 1, the plurality of grooves 43 are arranged so that the groove having the maximum depth among the plurality of grooves 43 is located midway between the center of the upper electrode 40 and the outer edge of the upper electrode 40. The depth distribution of may change stepwise.

Moreover, the distribution of the depths of the plurality of grooves 43 may increase stepwise from the center of the upper electrode 40 to the middle between the center and the outer edge of the upper electrode 40, or stepwise from the outer edge to the middle. may be increased to That is, among the plurality of grooves 43, the groove formed near the middle between the center of the upper electrode 40 and the outer edge of the upper electrode 40 may have a large depth. The depth of the grooves formed near the center and near the outer edge of the upper electrode 40 may be small.

3 together with FIGS. 1 and 2. FIG. FIG. 3 is an enlarged view from below of the upper electrode of the plasma processing apparatus according to one exemplary embodiment. As shown in FIG. 3, the plurality of grooves 43 may have an annular shape. The plurality of grooves 43 may extend in the circumferential direction with respect to the central axis AX.

In one embodiment, the number of grooves 43 may be five or more. In the example shown in FIG. 3, the number of grooves 43 is eleven. The plurality of grooves 43 are arranged along the radial direction perpendicular to the center axis AX. For example, the plurality of grooves 43 are radially arranged between the center 40a and the outer circumference 40b.

In one embodiment, the pitch of the plurality of gas holes 41 in the radial direction may be the same as the pitch of the plurality of grooves 43 in the radial direction. The “pitch” of the plurality of gas holes 41 is the distance between two adjacent gas holes among the plurality of gas holes 41 in the radial direction. The “pitch” of the plurality of grooves 43 is the distance between two adjacent grooves among the plurality of grooves 43 in the radial direction.

In one embodiment, the width of each of the plurality of grooves 43 may be 1/2 or more of the pitch of the plurality of gas holes 41 in the radial direction. That is, the width of the groove 43 provided between two adjacent gas holes among the plurality of gas holes 41 may be 1/2 or more of the radial distance between the two gas holes. .

In one embodiment, the total area of the open ends of the plurality of grooves 43 may be larger than the total area of the region 40c in which the plurality of grooves 43 are not formed on the lower surface of the upper electrode 40 . The area of the open ends of the plurality of grooves 43 may be 1/2 or more of the area of the lower surface of the upper electrode 40 (the area of the upper electrode 40 when viewed from below).

In one embodiment, the sidewalls 20 described above may provide one or more grooves 21 opening into the processing space S. In the example shown in FIG. 1, sidewall 20 provides a plurality of grooves 21 as one or more grooves 21 . As shown in FIG. 1, the plurality of grooves 21 may include grooves 21a, 21b, and 21c. The plurality of grooves 21 may include two or more grooves having different cross-sectional shapes. Each of the plurality of grooves 21 may have a unique ratio of its depth to its width. For example, the width of groove 21a is greater than the depth of groove 21a. The width of groove 21b is smaller than the depth of groove 21b.

The plurality of grooves 21 may have an annular shape. The plurality of grooves 21 may extend in the circumferential direction with respect to the center axis AX. Further, in one embodiment, at least one of the plurality of grooves 21 may be positioned above the upper surface of the substrate support portion 11 .

In one embodiment, the plasma processing apparatus 1 may further include a power source 3 and an introduction section 4 . The power source 3 is a generator of electromagnetic waves. The electromagnetic waves may be VHF waves or UHF waves. The band of VHF waves is 30 MHz to 300 MHz, and the band of UHF waves is 300 MHz to 3 GHz. The power supply 3 is connected to the upper electrode 40 via the impedance matching circuit 3m.

The introduction portion 4 forms part of the top portion 30 . The lead-in 4 is made of a dielectric such as aluminum oxide. The introduction portion 4 has a ring shape and extends in the circumferential direction along the outer periphery of the upper electrode 40 . Electromagnetic waves from the power supply 3 pass through the waveguide between the cover 31 and the upper electrode 40 and are introduced into the processing space S from the introduction section 4 . The electromagnetic waves excite the gas introduced into the processing space S to generate plasma from the gas.

Plasma processing apparatus 1 further comprises a gas source 2 . A gas from the gas source 2 is introduced into the processing space S through the gas diffusion chamber 42 and the plurality of gas holes 41 . The gas introduced into the processing space S from the gas source 2 is, for example, a film forming gas or a cleaning gas. The pressure in the processing space S is set within the range of 1 Pa to 300 Pa, for example. The width of the plurality of grooves 43 and the width of the plurality of grooves 21 are larger than the mean free path of gas molecules within the processing space S.

In the plasma processing apparatus 1 , gas introduced into the processing space S through the plurality of gas holes 41 forms a gas flow within the chamber 10 . The gases that form the gas stream reside within a plurality of grooves 43 provided by the upper electrode 40 . Since two or more of the plurality of grooves 43 have different cross-sectional shapes, the residence time of the gas in each of the plurality of grooves 43 is adjusted according to the cross-sectional shape of each groove. Therefore, it becomes possible to control the residence time of the gas introduced into the chamber 10 . Also, the density of active species in the plasma generated within the chamber 10 is proportional to the residence time of the gas. Therefore, according to the plasma processing apparatus 1, it is possible to control the density of active species. As a result, plasma processing of the substrate W with high in-plane uniformity becomes possible.

As described above, in one embodiment, the plurality of gas holes 41 may not include gas holes that open toward the plurality of grooves 43 . The plurality of gas holes 41 may be opened in a region 40c on the lower surface of the upper electrode 40 where the plurality of grooves 43 are not formed. In this embodiment, gas is not introduced directly into the plurality of grooves 43 . Therefore, a relatively long residence time of gas in the plurality of grooves 43 is ensured.

Also, as described above, in one embodiment, the two or more grooves described above among the plurality of grooves 43 may include a first groove (eg, groove 43a) and a second groove (eg, groove 43b). good. The width of the first groove may be greater than the depth of the first groove. The width of the second groove may be smaller than the depth of the second groove. In this embodiment, for example, when the width of the first groove and the width of the second groove are the same, the retention time of the gas retained in the second groove is longer than the retention time of the gas retained in the first groove. Time is long.

Further, as described above, in one embodiment, the plurality of grooves 43 may have an annular shape, may extend in the circumferential direction with respect to the central axis AX, and may extend along the central axis AX. They may be arranged along orthogonal radial directions. Also, the number of the plurality of grooves 43 may be five or more. According to this embodiment, it is possible to control the residence time of the gas in the radial direction so as to obtain a desired density distribution of the active species in the radial direction.

Further, as described above, in one embodiment, the distribution of the depths of the plurality of grooves 43 in the radial direction perpendicular to the central axis AX may change stepwise. According to this embodiment, the residence time of the gas in the radial direction can be controlled step by step so as to obtain a desired density distribution of the active species in the radial direction.

Also, as noted above, sidewall 20 may provide one or more grooves 21 in one embodiment. In this embodiment, gas resides in one or more grooves 21 formed in sidewall 20 . Therefore, according to this embodiment, it is possible to increase the density of active species in the vicinity of the sidewall 20 by increasing the retention time of the processing gas in the vicinity of the sidewall 20 .

Also, as described above, in one embodiment, the VHF band or the UHF band may be introduced into the processing space S via the introduction section 4 . The electromagnetic waves introduced from the introduction portion 4 can generate standing waves directly below the upper electrode 40 . According to the plasma processing apparatus 1, it is possible to control the residence time of the gas so as to obtain a desired density distribution of active species even under the condition that standing waves are generated.

Further, when a node of the standing wave is generated below the middle between the center and the outer edge of the upper electrode 40, the groove located in the middle among the plurality of grooves 43 is arranged to have the maximum depth. , the depth distribution of the plurality of grooves 43 may change stepwise. In this case, the residence time of the gas becomes longer at the node position of the standing wave where the potential change is small, so it is possible to obtain a relatively uniform density distribution of the active species in the radial direction.

While various exemplary embodiments have been described above, various additions, omissions, substitutions, and modifications may be made without being limited to the exemplary embodiments described above. Also, elements from different embodiments can be combined to form other embodiments.

For example, the cross-sectional shape of each of the plurality of grooves 43 may be a shape other than a rectangle. The cross-sectional shape of each of the plurality of grooves 43 may be polygonal and may include curved lines. Each of the plurality of grooves 43 may have a tapered shape with a maximum width at its open end.

Further, the distribution of the depth of each of the plurality of grooves 43 changes stepwise in the radial direction such that the groove having the smallest depth among the plurality of grooves 43 is positioned near the outer edge of the upper electrode 40. may For example, the distribution of depths of the plurality of grooves 43 may decrease stepwise from the center of the upper electrode 40 to the outer edge of the upper electrode in the radial direction. Specifically, the groove formed near the center of the upper electrode 40 among the plurality of grooves 43 may have a large depth, and the groove formed near the outer edge of the upper electrode 40 among the plurality of grooves 43 may have a large depth. can be small. If the gas is introduced into the chamber from the center of the top electrode 40 and flows radially outward, the convection time of the gas just below the center of the top electrode 40 is longer than the convection time of the gas just below the center of the top electrode 40 , without the plurality of grooves 43 . The residence time of the gas just below the outer edge of the However, with the plurality of grooves 43 having such a depth distribution, it is possible to reduce the unevenness of the gas residence time in the radial direction.

Also, the pitch of the plurality of gas holes 41 in the radial direction may not be constant. Also, the pitch of the plurality of grooves 43 in the radial direction may not be constant. A plurality of grooves 43 may be connected to each other. For example, grooves 43 may be connected to each other by radially extending grooves.

From the foregoing description, it will be appreciated that various embodiments of the present disclosure have been set forth herein for purposes of illustration, and that various changes may be made without departing from the scope and spirit of the present disclosure. Will. Therefore, the various embodiments disclosed herein are not intended to be limiting, with a true scope and spirit being indicated by the following claims.

DESCRIPTION OF SYMBOLS 1... Plasma processing apparatus 4... Introduction part 10... Chamber 11... Substrate support part 20... Side wall 21... One or more grooves 30... Ceiling part 40... Upper electrode 40c... Region 41... Plural gas hole, 43: a plurality of grooves, S: processing space, AX: central axis.

Claims (11)

a chamber providing a processing space therein;
a substrate support provided within the chamber;
with
The chamber is
a side wall extending laterally of the processing space so as to surround the processing space;
a ceiling extending above the substrate support, the ceiling including an upper electrode providing a plurality of gas holes opening toward the processing space for introducing gases into the processing space;
has
the upper electrode provides a plurality of grooves opening toward the processing space;
The plurality of grooves includes two or more grooves having cross-sectional shapes different from each other,
Plasma processing equipment. the plurality of gas holes do not include gas holes that open toward the plurality of grooves, and are open in regions where the plurality of grooves are not formed on the lower surface of the upper electrode;
The plasma processing apparatus according to claim 1. each of the plurality of grooves has a unique ratio of its depth to its width;
each of said two or more grooves has said ratio different from said ratio of other grooves among said two or more grooves;
The plasma processing apparatus according to claim 1 or 2. the two or more grooves include a first groove and a second groove;
the width of the first groove is greater than the depth of the first groove, and the width of the second groove is less than the depth of the second groove;
The plasma processing apparatus according to claim 3. the plurality of grooves have an annular shape and extend in a circumferential direction with respect to a central axis of the upper electrode;
The number of the plurality of grooves is five or more,
The plurality of grooves are arranged along a radial direction orthogonal to the central axis,
The plasma processing apparatus according to claim 4. 6. The plasma processing apparatus according to claim 5, wherein a pitch of said plurality of gas holes in said radial direction is the same as a pitch of said plurality of grooves in said radial direction. 7. The plasma processing apparatus according to claim 5, wherein the width of each of said plurality of grooves is 1/2 or more of the pitch of said plurality of gas holes in said radial direction. 8. The plasma processing apparatus according to any one of claims 1 to 7, wherein a distribution of depths of said plurality of grooves in a radial direction orthogonal to a central axis of said upper electrode changes stepwise. 9. The plasma processing apparatus according to any one of claims 1 to 8, wherein an area of an open end of said plurality of grooves is larger than an area of a region where said plurality of grooves are not formed on the lower surface of said upper electrode. the sidewalls provide one or more grooves opening into the processing space;
the one or more grooves have an annular shape and extend circumferentially with respect to a central axis of the sidewall;
The plasma processing apparatus according to any one of claims 1-9. an inlet formed of a dielectric material and extending circumferentially along the outer periphery of the upper electrode for propagating electromagnetic waves, which are VHF or UHF waves, to generate plasma in the processing space. further comprising a part,
The plasma processing apparatus according to any one of claims 1-10.

Images