Edge Ring and Etching Device

Abstract

The present invention provides an edge ring and an etching apparatus. An edge ring capable of suppressing consumption of an inner peripheral portion thereof is provided. An edge ring surrounds an outer periphery of an object to be etched supported by a substrate support portion in a plasma processing chamber. The edge ring has an inclined surface that becomes lower from an outer peripheral portion toward an inner peripheral portion. Let the thickness of the edge ring before plasma processing at a location Xa on the inclined surface, which is closer to the inner peripheral portion than a midline equidistant from the innermost periphery and the outermost periphery of the edge ring, be T1, let the thickness of the edge ring before plasma processing at a location Xb on the inclined surface, which is closer to the outer peripheral portion than the midline, be T2, let the thickness of the edge ring after plasma processing at the location Xa be T3, and let the thickness of the edge ring after plasma processing at the location Xb be T4. At this time, the relationship T2 / T1 > T4 / T3 is satisfied.

Description

Technical Field

[0001] The present disclosure relates to an edge ring and an etching apparatus. Background Art

[0002] Etching and other plasma processes cause consumption of an edge ring which is a component disposed near a substrate. When the thickness of the edge ring decreases due to the consumption of the edge ring, the shape of the outer sheath at the upper part of the edge ring changes, and the incident direction of ions from the plasma incident on the edge region of the substrate is inclined inward with respect to the vertical direction (hereinafter also referred to as "tilt"). As a result, the in-plane uniformity of the plasma process is impaired. Since the consumption of the inner peripheral portion of the edge ring, which is closer to the edge region of the substrate, has a greater influence on the tilt, an edge ring capable of suppressing the consumption of the inner peripheral portion is desired. In addition, the edge ring is also referred to as a focus ring.

[0003] For example, Patent Document 1 provides a plasma processing method that can minimize the adverse effects on processing results such as etching shape caused by the consumption of the focus ring and can extend the service life of the focus ring. In Patent Document 1, a DC power supply is connected to the focus ring, and a prescribed DC voltage is applied to the focus ring based on the degree of consumption of the focus ring, the detection result of the electric field change above the focus ring, or the plasma processing result that has been implemented.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2007-258417 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] The present disclosure provides an edge ring capable of suppressing the consumption of the inner peripheral portion of the edge ring.

[0009] Solutions for Solving the Problems

[0010] According to one technical solution of the present disclosure, an edge ring is provided, which surrounds the outer periphery of an object to be etched supported by a substrate support portion in a plasma processing chamber. Wherein, the edge ring has an inclined surface that becomes lower from the outer peripheral portion toward the inner peripheral portion. The thickness of the edge ring before plasma processing at a location Xa on the inclined surface, which is closer to the inner peripheral portion than a midline equidistant from the innermost and outermost peripheries of the edge ring, is set as T1. The thickness of the edge ring before plasma processing at a location Xb on the inclined surface, which is closer to the outer peripheral portion than the midline, is set as T2. The thickness of the edge ring after plasma processing at the location Xa is set as T3. The thickness of the edge ring after plasma processing at the location Xb is set as T4. At this time, the relationship of T2 / T1 > T4 / T3 is satisfied.

[0011] Effects of the Invention

[0012] According to one technical solution, an edge ring capable of suppressing the consumption of the inner peripheral portion of the edge ring can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 (a) of is a diagram showing the edge ring of the reference example, Figure 1 and (b) of is a diagram showing the edge ring of the embodiment.

[0014] Figure 2 is a diagram showing an example of the periphery of the edge ring of the embodiment.

[0015] Figure 3 is a graph showing the electric field strength of the edge rings of the embodiment and the reference example.

[0016] Figure 4 and (a) of Figure 4 and (b) of are graphs showing the correlation between the electric field strength ratio and the consumption rate ratio of the inner peripheral portion to the outer peripheral portion of the edge rings of the embodiment and the reference example.

[0017] Figure 5 is a top view showing the edge ring of the first embodiment.

[0018] Figure 6 is a cross-sectional view showing the edge ring of the first embodiment ( Figure 5 cross-sectional view taken along line A - A of ).

[0019] Figure 7 is a cross-sectional view showing the edge rings of the second to fourth embodiments.

[0020] Figure 8 is a schematic cross-sectional view showing an example of the etching apparatus of the embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] Hereinafter, embodiments for implementing the present disclosure will be described with reference to the drawings. In each drawing, the same reference numerals are assigned to the same structural parts, and repeated descriptions are sometimes omitted.

[0022] [Edge ring]

[0023] First, with reference to Figure 1 and Figure 2 the edge ring FR of the embodiment will be described. Figure 1 (a) of is a diagram showing the edge ring FR' of the reference example, Figure 1 and (b) of is a diagram showing the edge ring FR of the embodiment. Figure 2 is a diagram showing an example of the edge ring FR of the embodiment and its periphery.

[0024] The edge ring FR is a ring-shaped member configured to surround the outer periphery of a substrate (hereinafter referred to as "wafer W") as an example of an object to be etched, and this substrate is supported by a substrate support portion ST in a plasma processing chamber 12 of an etching apparatus 10 (refer to Figure 8 ). In one example, the edge ring FR is formed of a conductive material such as Si or SiC. The cover ring 14a is a ring-shaped member configured to surround the outer periphery of the edge ring FR. In one example, the cover ring 14a is formed of an insulating material such as quartz. The etching apparatus 10 is a device for performing plasma processing (etching) on an object to be etched (etching target film) on the wafer W. The substrate support portion ST includes a base 16 and an electrostatic chuck 18. Other structures of the etching apparatus 10 will be described later.

[0025] The Figure 1 edge ring FR' of the reference example in (a) of and Figure 1 the edge ring FR of the embodiment in (b) of (hereinafter also referred to as Taper FR) will be described. The shapes of the upper surfaces of the edge ring FR' of the reference example and the edge ring FR of the embodiment are different, and the other shapes are the same.

[0026] Figure 1 The longitudinal section of the edge ring FR' of the reference example shown in (a) of is a surface surrounded by each cut line when cutting along the radial direction of the edge ring FR' the inner peripheral side surface 160b, the outer peripheral side surface 160d, the bottom surface 160e connecting the lower ends of the inner peripheral side surface 160b and the outer peripheral side surface 160d, and the upper surface 160a connecting the upper ends of the inner peripheral side surface 160b and the outer peripheral side surface 160d. The upper surface 160a of the edge ring FR' includes a surface 160a1, a surface 160a2, and a step portion 160c.

[0027] Figure 1The longitudinal section of the edge ring FR in the embodiment shown in (b) is a surface surrounded by each cut line when the inner peripheral side surface 60b, the outer peripheral side surface 60d, the bottom surface 60e connecting the lower end of the inner peripheral side surface 60b and the lower end of the outer peripheral side surface 60d, and the upper surface 60a connecting the upper end of the inner peripheral side surface 60b and the upper end of the outer peripheral side surface 60d are cut along the radial direction of the edge ring FR. The upper surface 60a of the edge ring FR includes a surface 60a1, a surface 60a2, a surface 60a3, and a step portion 60c. In addition, with respect to the intermediate line Ax that is equidistant from the inner peripheral side surface 60b and the outer peripheral side surface 60d of the edge ring FR when viewed in the horizontal direction, the inner region thereof is set as the inner peripheral portion (FR inner peripheral portion) of the edge ring FR, and the outer region thereof is set as the outer peripheral portion (FR outer peripheral portion) of the edge ring FR. Similarly, with respect to an intermediate line (not shown) that is equidistant from the inner peripheral side surface 160b and the outer peripheral side surface 160d of the edge ring FR' when viewed in the horizontal direction, the inner region thereof is set as the inner peripheral portion (FR' inner peripheral portion) of the edge ring FR', and the outer region thereof is set as the outer peripheral portion (FR' outer peripheral portion) of the edge ring FR'.

[0028] In the edge ring FR' supported by the base 16 and the annular member 15, the surfaces 160a1 and 160a2 in the upper surface 160a are horizontal surfaces. In addition, in the edge ring FR supported by the base 16 and the annular member 15, the surfaces 60a2 and 60a3 in the upper surface 60a are horizontal surfaces, and the surface 60a1 is an inclined surface that becomes lower from the outer peripheral portion of the edge ring FR toward the inner peripheral portion. The bottom surface 160e, the surface 160a1, and the surface 160a2 are substantially parallel surfaces. Similarly, the bottom surface 60e, the surface 60a2, and the surface 60a3 are substantially parallel surfaces. In this specification, the above-mentioned each surface being a "horizontal surface" means that when the edge rings FR' and FR are arranged on the ring support surface 16b of the base 16, the surfaces 160a1 and 160a2, and the surfaces 60a2 and 60a3 are horizontal surfaces. Similarly, in this specification, an "inclined surface" means that when the edge ring FR is arranged on the ring support surface 16b of the base 16, the surface 60a1 is an inclined surface that becomes lower from the outer peripheral portion toward the inner peripheral portion.

[0029] The base 16 has a central region (central support surface 16a) for supporting the electrostatic chuck 18 and an annular region (ring support surface 16b) for supporting the edge rings FR and FR'. The ring support surface 16b of the base 16 surrounds the central support surface 16a in a plan view. The electrostatic chuck 18 is arranged on the central support surface 16a of the base 16, and the edge rings FR and FR' are arranged on the ring support surface 16b of the base 16.

[0030] The base 16 includes a conductive member. The conductive member of the base 16 functions as a lower electrode. The upper surface of the electrostatic chuck 18 has a substrate support surface 18a, and the wafer W is disposed above the substrate support surface 18a. The edge rings FR, FR' are arranged so as to surround the wafer W above the electrostatic chuck 18.

[0031] As Figure 2 shown, the ring assembly 14 includes an edge ring FR and a cover ring 14a. A part of the edge ring FR and the cover ring 14a are supported by an annular member 15. The annular member 15 is formed of an insulator such as quartz. The annular member 15 is configured to surround the outer periphery of the base 16.

[0032] The height (thickness) of the outermost periphery of the edge ring FR is substantially the same as the height (thickness) of the innermost periphery of the cover ring 14a. That is, there is no height difference between the upper surface of the outermost periphery of the edge ring FR and at least the upper surface of the innermost periphery of the cover ring 14a. The outer peripheral side of the lower surface of the cover ring 14a protrudes downward in a ring shape more than the inner peripheral side and engages with a ring-shaped recess formed on the outer peripheral side of the upper surface of the annular member 15. In addition, the edge ring FR may be disposed on the ring support surface 16b of the base 16 with a heat transfer sheet interposed therebetween.

[0033] Returning to Figure 1 , the edge rings FR, FR' are configured such that the ends of the wafer W protrude outward beyond the inner peripheral sides 60b, 160b of the edge rings FR, FR'. On the upper surfaces 60a, 160a of the edge rings FR, FR', step portions 60c, 160c are formed near the ends of the wafer W and at positions outside the ends of the wafer W. The surfaces 60a3, 160a2 of the upper surfaces 60a, 160a of the edge rings FR, FR' from the innermost periphery to the step portions 60c, 160c are flat horizontal surfaces. Hereinafter, the surface 60a3 is referred to as the first surface.

[0034] In Figure 1In the edge ring FR' of the reference example of (a), the upper surface 160a has a surface 160a2 from the innermost circumference of the edge ring FR' to the step portion 160c and a surface 160a1 from the step portion 160c to the outermost circumference of the edge ring FR'. The surface 160a2 has a width of about 1 to 2 mm from the upper end of the inner peripheral side surface 160b. The thickness of the portion of the edge ring FR' from the inner peripheral side surface 160b of the edge ring FR' to the step portion 160c is the same. In addition, the thickness of the portion of the edge ring FR' from the step portion 160c to the outer peripheral side surface 160d of the edge ring FR' is the same. The thickness of the portion of the edge ring FR' from the step portion 160c to the outer peripheral side surface 160d of the edge ring FR' is thicker than the thickness of the portion of the edge ring FR' from the inner peripheral side surface 160b of the edge ring FR' to the step portion 160c. That is, the height of the surface 160a1 on the outer peripheral side of the step portion 160c is higher than the height of the surface 160a2 on the inner peripheral side of the step portion 160c.

[0035] In contrast, in Figure 1 the edge ring FR of the embodiment of (b), the upper surface 60a includes a first surface 60a3 from the inner peripheral side surface 60b of the edge ring FR to the step portion 60c, an inclined surface 60a1 on the outer peripheral side of the step portion 60c, and a second surface 60a2. The first surface 60a3 has a width of about 1 to 2 mm from the upper end of the inner peripheral side surface 60b. The first surface 60a3 and the second surface 60a2 are both horizontal planes when the edge ring FR is disposed on the ring support surface 16b of the base 16. The thickness of the portion of the edge ring FR from the inner peripheral side surface 60b to the step portion 60c is the same. The second surface 60a2 can be either a horizontal plane or an inclined surface when the edge ring FR is disposed on the ring support surface 16b of the base 16. The inclined surface 60a1 is the surface between the first surface 60a3 and the second surface 60a2. Each of the first surface 60a3, the second surface 60a2, and the inclined surface 60a1 is flat. In the inner peripheral portion of the inclined surface 60a1, the thickness of the portion of the edge ring FR outside the step portion 60c is thinner than the thickness of the portion of the edge ring FR inside the step portion 60c, while in the outer peripheral portion of the inclined surface 60a1, the thickness of the portion of the edge ring FR outside the step portion 60c is thicker than the thickness of the portion of the edge ring FR inside the step portion 60c.

[0036] According to this structure, in Figure 1 the edge ring FR' of the reference example of (a), the thickness of the portion of the edge ring FR' outside the step portion 160c is the same. In contrast, in Figure 1 the edge ring FR of the embodiment of (b), the thickness of the portion of the edge ring FR outside the step portion 60c becomes thicker (inclined surface 60a1) toward the outside.

[0037] Accordingly, the thickness of the portion from the inner peripheral side surfaces 60b and 160b to the stepped portions 60c and 160c of the edge rings FR and FR’ is the same in each of the edge rings FR and FR’, but outside the stepped portions 60c and 160c, the relative height with respect to the upper surface of the wafer W is different between the edge ring FR and the edge ring FR’. That is, in the edge ring FR’ of the reference example of (a) in Figure 1 since the upper surface 160a is also a horizontal plane outside the stepped portion 160c, the relative height of the upper surface 160a with respect to the upper surface of the wafer W is the same. In contrast, in the edge ring FR of the embodiment of (b) in Figure 1 at least in the inclined surface 60a1 of the portion of the upper surface 60a located outside the stepped portion 60c, the relative height with respect to the upper surface of the wafer W becomes lower from the outer peripheral portion toward the inner peripheral portion.

[0038] As will be described later, for the edge rings FR and FR’, high-frequency power is applied to the base 16 from the first high-frequency power supply HFS and / or the second high-frequency power supply LFS (refer to Figure 8 ), and high-frequency current (RF current) flows in the edge rings FR and FR’.

[0039] Under the same conditions, the overall electric field strength of the outer sheath formed by the high-frequency current above the edge rings FR and FR’ is constant, and for example, it is impossible to make the electric field strength zero. By changing the height of the portions of the upper surfaces 60a and 160a of the edge rings FR and FR’ that are closer to the outer peripheral side than the stepped portions 60c and 160c, it is possible to relatively change the electric field strength of the outer peripheral portion and the inner peripheral portion.

[0040] For example, in the edge ring FR’ of the reference example, the relative height of the portion of the upper surface 160a located outside the stepped portion 160c with respect to the upper surface of the wafer W is the same. Therefore, the proportion of the high-frequency current flowing through the surface layer of the edge ring FR’ is substantially the same in the outer peripheral portion and the inner peripheral portion. As a result, the electric field strength of the outer sheath also becomes substantially the same value in the outer peripheral portion and the inner peripheral portion.

[0041] In addition, in the edge ring FR of the embodiment, in the inclined surface 60a1, the relative height of the inner peripheral portion with respect to the upper surface of the wafer W is lower than the relative height of the outer peripheral portion with respect to the upper surface of the wafer W. Therefore, the high-frequency current flowing through the surface layer of the edge ring FR changes relatively, and the electric field strength of the outer peripheral portion of the outer sheath is higher than the electric field strength of the inner peripheral portion of the outer sheath.

[0042] Figure 3The graph shows the simulation results of the electric field strength (vertical axis) generated by the high-frequency current flowing through the edge rings FR and FR’. The electric field strength is plotted against the position in the radial direction of the edge rings FR and FR’. 150 mm on the graph represents the position of the end A of the wafer W, which is at a radius of 150 mm from the center of the wafer W. 180 mm on the graph represents the position of the end B of the edge rings FR and FR’, which is at a distance of 180 mm from the center of the wafer W (see Figure 1 in (a) of Figure 1 and (b) of

[0043] <Simulation Conditions>

[0044] The angle of the inclined surface 60a1 of the edge ring FR with respect to the horizontal plane (tilt angle): 3°

[0045] The angle of the surface 160a1 of the edge ring FR’ with respect to the horizontal plane: 0°

[0046] Etching gas: A mixed gas of C4F6 gas, O2 gas, and Ar gas

[0047] Pressure: 50 mTorr (6.67 Pa)

[0048] RF (HF) output from the first high-frequency power supply HFS: 100 MHz

[0049] RF (LF) output from the second high-frequency power supply LFS: 3.2 MHz

[0050] It is set to supply the RF (HF) of 100 MHz output from the first high-frequency power supply HFS and the RF (LF) of 3.2 MHz output from the second high-frequency power supply LFS to the lower electrode.

[0051] Figure 3 The curve S in the graph of Figure 1 represents the electric field strength at each position from the end A of the wafer W to the end B of the edge ring FR’ in the radial direction of the edge ring FR’ shown in (a) of

[0052] Figure 3 In the curve S, at positions on the outer peripheral side of the step portion 160c near about 153 mm, in the range of about 153 mm to about 175 mm from the center of the wafer W in the radial direction, the electric field strength is substantially the same. Figure 1The electric field strength at each position in the radial direction of the edge ring FR (Taper FR) in the embodiment shown in (b). In curve T, at positions on the outer peripheral side of the step portion 60c near about 153 mm, within the range of about 153 mm to about 175 mm from the center of the wafer W in the radial direction, there is a difference in the electric field strength between the outer peripheral portion and the inner peripheral portion. In particular, in the edge ring FR, within the range of about 153 mm to about 160 mm from the center of the wafer W, the electric field strength of the inner peripheral portion is lower than that of the edge ring FR', and within the range of about 170 mm to about 180 mm from the center of the wafer W, the electric field strength of the outer peripheral portion is higher than that of the edge ring FR'.

[0053] Based on the above results, in the edge ring FR of the embodiment, since the upper surface 60a has the inclined surface 60a1 such that the inner peripheral portion is lower than the outer peripheral portion in the radial direction, in the radial direction of the edge ring FR, the electric field strength of the FR outer peripheral portion of the outer sheath can be made higher than the electric field strength of the FR inner peripheral portion of the outer sheath. That is, as shown in (b) of Figure 1 For the edge ring FR, by using the inclined surface 60a1 that becomes lower from the FR outer peripheral portion toward the FR inner peripheral portion, the electric field strength of the inner peripheral portion can be made relatively smaller than that of the outer peripheral portion. Thus, the energy of the ions incident into the outer sheath is smaller in the FR inner peripheral portion with a relatively lower electric field strength than in the FR outer peripheral portion with a relatively higher electric field strength. As a result, the consumption rate of the edge ring FR can be made lower in the FR inner peripheral portion than in the FR outer peripheral portion.

[0054] In this way, in the edge ring FR of the embodiment shown in (b) of Figure 1 , since it has the structure in which the upper surface 60a is inclined with the inner peripheral portion being lower than the outer peripheral portion, an electric field strength difference is generated between the outer peripheral side and the inner peripheral side of the edge ring FR. Thus, the local consumption rate of the edge ring FR can be intentionally controlled.

[0055] As an example of the positions Xa and Xb shown in Figure 2 , the relative height of the position Xa on the upper surface 60a located in the inner peripheral portion with respect to the intermediate line Ax is lower than the relative height of the position Xb on the upper surface 60a located in the outer peripheral portion with respect to the intermediate line Ax. For example, in the edge ring FR of the embodiment shown in curve T of the graph in Figure 3 , at the position Xa in the inner peripheral portion (for example, about 153 mm from the center of the wafer W), the electric field strength can be made relatively lower than that at the position Xb in the outer peripheral portion (for example, about 176 mm from the center of the wafer W). In addition, in the edge ring FR' of the reference example shown in curve S of the graph in Figure 3 , the electric field strengths of the position Xa in the inner peripheral portion and the position Xb in the outer peripheral portion are substantially the same.

[0056] Next, regarding the consumption of the edge rings FR' and FR, experiments were conducted under the following experimental conditions.

[0057] <Experimental conditions>

[0058] Angle (tilt angle) of the inclined surface 60a1 of the edge ring FR with respect to the horizontal plane: 3°;

[0059] Angle of the surface 160a1 of the edge ring FR' with respect to the horizontal plane: 0°;

[0060] Etch target (etch target film): SiO2;

[0061] Etching gas: Mixed gas of C4F6 gas, O2 gas, and Ar gas;

[0062] In this experiment, the substrate W was etched for a cumulative 200 hours.

[0063] As a result of the experiment, when the consumption rate of the edge ring FR' was normalized to 1, at a position 3 mm from the innermost circumference of the edge rings FR' and FR, that is, at a position 153 mm from the center of the wafer W, the ratio of the consumption rate of the edge ring FR to the consumption rate of the edge ring FR' was approximately 0.6 times. At a position 4 mm from the outermost circumference of the edge rings FR' and FR, that is, at a position 176 mm from the center of the wafer W, the ratio of the consumption rate of the edge ring FR to the consumption rate of the edge ring FR' was approximately 0.9 times. When the tilt angle θ of the inclined surface of the edge ring FR in the above <Experimental conditions> with respect to the horizontal plane was set to 7° and other conditions were the same, in the inner circumference part, the ratio of the consumption rate of the edge ring FR to the consumption rate of the edge ring FR' was approximately 0.5 times, and in the outer circumference part, the ratio of the consumption rate of the edge ring FR to the consumption rate of the edge ring FR' was approximately 1.0 times. In either case, the consumption amount (consumption rate) in the inner circumference part was less than that in the outer circumference part.

[0064] In the edge ring FR of the embodiment, the height of the outer peripheral portion of the upper surface is made higher than the height of the inner peripheral portion. Thereby, compared with the edge ring FR' of a flat reference example having the same height on the upper surface, the consumption amount (change amount) of the inner peripheral portion near the wafer W can be reduced. That is, according to the edge ring FR of the embodiment, the consumption rate of the edge ring FR can be made lower in the FR inner peripheral portion than in the FR outer peripheral portion. That is, the thickness of the edge ring FR before plasma treatment at the location Xa is set to T1, the thickness of the edge ring FR before plasma treatment at the location Xb on the inclined surface 60a1 on the upper surface 60a and closer to the outer peripheral portion than the intermediate line Ax is set to T2, the thickness of the edge ring FR after plasma treatment at the location Xa is set to T3, and the thickness of the edge ring FR after plasma treatment at the location Xb is set to T4. At this time, the consumption amount (consumption rate) of the inner peripheral portion can be expressed as T1 - T3, and the consumption amount (consumption rate) of the outer peripheral portion can be expressed as T2 - T4, and the relationship of (T1 - T3) < (T2 - T4) holds. In addition, tilting can be suppressed, and etching can be performed vertically also at the edge of the wafer W. Thereby, the in-plane uniformity of etching is improved. In addition, by intentionally controlling the local consumption rate of the edge ring FR, the life of the edge ring FR is extended, and there is also an advantage in terms of cost. Moreover, the deviation of the tilt amount between the nth (n≥1) wafer W and the (n + 1)th wafer W can be improved.

[0065] Figure 4 (a) and Figure 4 of (b) show the edge ring FR of the embodiment in which only the inclined surface 60a1 is inclined and the second surface 60a2 is a horizontal plane in the upper surface 60a shown in Figure 1 (b) of and Figure 1 the edge ring FR' of the reference example with a flat upper surface 160a shown in Figure 3 the correlation between the simulation results shown and the above experimental results.

[0066] Figure 4 (a) has the ratio of the electric field strengths of the electric fields generated by the high-frequency currents flowing through the edge rings FR and FR' of the inner peripheral portion and the outer peripheral portion on the horizontal axis ( Figure 3 ), and the consumption rate ratio on the vertical axis. Figure 4 (a) is a graph obtained by plotting this correlation. In addition, the inner peripheral portion is at a position 153 mm away from the center of the wafer W, and the outer peripheral portion is at a position 176 mm away from the center of the wafer W. Figure 1The consumption rate of the outer peripheral portion of the edge ring FR' in the reference example shown in (a) is normalized to a consumption rate ratio of "1", and the electric field strength of the outer peripheral portion of the edge ring FR' is normalized to an electric field strength ratio of "1". F1-inner represents the inner peripheral portion of the edge ring FR', F1-outer represents the outer peripheral portion of the edge ring FR', T1-inner represents the inner peripheral portion of the edge ring FR, and T1-outer represents the outer peripheral portion of the edge ring FR.

[0067] As Figure 4 shown in (a) and Figure 4 shown in (b), in the edge ring FR' of the reference example, the electric field strength ratio and consumption rate ratio of the inner peripheral portion (F1-inner) to the outer peripheral portion (F1-outer) are substantially the same. In contrast, in the edge ring FR of the embodiment, the electric field strength of the outer peripheral portion (T1-outer) is the same as that of the outer peripheral portion (F1-outer) of the edge ring FR', but the electric field strength ratio of the inner peripheral portion (T1-inner) of the edge ring FR to the outer peripheral portion (F1-outer) of the edge ring FR' and the outer peripheral portion (T1-outer) of the edge ring FR is 0.7 times. The consumption rate ratio of the edge ring FR in the embodiment is 0.9 times for the outer peripheral portion (T1-outer) with respect to the outer peripheral portion (F1-outer) of the edge ring FR' and 0.6 times for the inner peripheral portion (T1-inner) with respect to the outer peripheral portion (F1-outer) of the edge ring FR'. That is, in the edge ring FR, the smaller the relative height ratio of the edge ring FR to the wafer W, the smaller the consumption rate ratio. In addition, in the edge ring FR, the relative height of the edge ring FR at the inner peripheral portion (inner) with respect to the wafer W is lower than that at the outer peripheral portion, the electric field strength ratio of the inner peripheral portion of the edge ring FR to the outer peripheral portion decreases, and the consumption rate ratio decreases. As described above, by changing the relative height ratio of the edge ring FR to the wafer W, the electric field strength ratio and consumption rate ratio of the inner peripheral portion to the outer peripheral portion can be changed, and thus, the consumption amount of the inner peripheral portion of the edge ring FR can be reduced.

[0068] [First to Fourth Embodiments of Edge Ring]

[0069] (First Embodiment)

[0070] Next, refer to Figure 5 and Figure 6 to describe the edge ring FR of the first embodiment. Figure 5 is a top view showing the edge ring FR of the first embodiment. Figure 6 is a cross-sectional view showing the edge ring FR of the first embodiment ( Figure 5 cross-sectional view A-A of

[0071] AsFigure 5 As shown, in the first embodiment, an edge ring FR is arranged around the outer periphery of a wafer W with a radius of approximately 150 mm. The edge ring FR shares the axis with the central axis O of the wafer W and is arranged in a substantially concentric circle shape.

[0072] The inner diameter I of the edge ring FR is approximately 300 mm to approximately 305 mm, the outer diameter J of the edge ring FR is approximately 360 - 365 mm, and the radial width C of the edge ring FR is approximately 28 mm to 32 mm. The radial width E of the edge ring FR from the innermost circumference to the step portion 60c only needs to be approximately 1 mm or more and approximately 2 mm or less.

[0073] The upper surface 60a of the edge ring FR has an inclined surface 60a1 and a second surface 60a2 outside the step portion 60c. The upper surface 60a of the edge ring FR has a first surface 60a3 inside the step portion 60c. The first surface 60a3, the inclined surface 60a1, and the second surface 60a2 are flat. The upper surface 60a can be partially inclined or entirely inclined. That is, the second surface 60a2 can be either an inclined surface or a horizontal surface. In the example of the Figure 5 A - A cross-section shown Figure 6 the second surface 60a2 is a horizontal surface.

[0074] The second surface 60a2 has a width G that is approximately 5 mm or more and approximately 7 mm or less in the radial direction from the innermost circumferential side of the edge ring FR. The width of the inclined surface 60a1 in the radial direction can also be approximately 20 mm or more and approximately 30 mm or less. In the present disclosure, the inclined surface 60a1 can be a flat surface that uniformly decreases from the outer peripheral portion toward the inner peripheral portion such that the inclination angle θ (°) with respect to the horizontal plane is 2.5° or more and 10° or less. When the inclination angle θ (°) is less than 2.5°, the effect of reducing the consumption of the inner peripheral portion of FR is not sufficient. When the inclination angle θ (°) exceeds 10°, it may cause deterioration of the in-plane uniformity (difficulty in suppressing inclination) at the initial stage of substrate processing (before the outer peripheral portion of the edge ring is consumed). When the angle becomes larger, the deformation of the lower end of the outer sheath becomes larger, and it becomes difficult to control the inclination (the inclination (outward inclination) toward the outside of the substrate edge becomes larger), so it needs to be set to 10° or less. Considering both the view of inclination controllability and the degree of reduction in consumption of the inner peripheral portion of the edge ring, it is more preferable that the inclination angle θ (°) is 3° or more and 7° or less. That is, by setting the inclination angle θ (°) to 3° or more, the ratio of the high-frequency current flowing through the inner peripheral portion of FR to the high-frequency current flowing through the outer peripheral portion of FR is further decreased, and the effect of reducing the consumption of the inner peripheral portion can be sufficiently obtained. In addition, by setting the inclination angle θ (°) to 7° or less, it is possible to prevent the inclination amount of the outward inclination (outward inclination) at the edge of the wafer W from becoming large, and it is possible to perform etching of a vertical shape in the plane of the wafer W including the edge of the wafer W.

[0075] The thickness D of the innermost circumference of the edge ring FR is approximately 3 mm. The maximum value of the thickness H of the outermost circumference of the edge ring FR is approximately 3.5 mm or more and approximately 7.0 mm or less. The height F of the step portion 60c is approximately 0.2 mm.

[0076] By Figure 6 The inclined surface 60a1 indicated by the dashed line represents the height of the edge ring FR before plasma processing, and the inclined surface 60a1 indicated by the solid line is an example of the height of the edge ring FR after plasma processing. The edge ring FR before plasma processing may also refer to an unused (new) edge ring FR. In addition, the edge ring FR after plasma processing may also refer to a used-up edge ring FR, that is, an edge ring FR after being consumed by plasma processing (for example, at the time of replacement).

[0077] A location Xa on the upper surface 60a that is located on the inclined surface 60a1 and is closer to the inner peripheral portion than the intermediate line Ax that is equidistant from the innermost and outermost circumferences of the edge ring FR when viewed in the horizontal direction is set, and the thickness of the edge ring FR before plasma processing at the location Xa is set to T1. The thickness of the edge ring FR before plasma processing at a location Xb on the upper surface 60a that is located on the inclined surface 60a1 and is closer to the outer peripheral portion than the intermediate line Ax is set to T2.

[0078] The thickness of the edge ring FR after plasma treatment at the location Xa is set as T3, and the thickness of the edge ring FR after plasma treatment at the location Xb is set as T4. At this time, the relationship of T2 / T1 > T4 / T3 holds.

[0079] (Second to Fourth Embodiments)

[0080] Next, refer to Figure 7 to describe the edge ring FR of the second to fourth embodiments. Figure 7 FIG. is a cross-sectional view showing the edge ring FR of the second to fourth embodiments. In the second to fourth embodiments, the aspect different from the first embodiment is that the inclined surface 60a1 on the upper surface 60a of the edge ring FR is not a flat surface. Other structures of the edge ring FR are the same as those of the first embodiment. That is, in the second to fourth embodiments, the inclined surface 60a1 can be at least any one of a concave surface, a convex surface, and a curved surface.

[0081] In Figure 7 the second embodiment of (a), the inclined surface 60a1 becomes a concave surface. In Figure 7 the third embodiment of (b), the inclined surface 60a1 becomes a convex surface. In Figure 7 the fourth embodiment of (c), the outer peripheral portion of the inclined surface 60a1 becomes a convex surface, and the inner peripheral portion becomes a concave surface.

[0082] In the second to fourth embodiments, the radial distance between the positions Xmax and Xmin of the horizontal planes corresponding to the positions where the height from the edge ring FR to the inclined surface 60a1 in the inclined surface 60a1 becomes the maximum value Hmax and the minimum value Hmin is set as (Xmax - Xmin). The relative amount of the height difference (Hmax - Hmin) between the maximum value and the minimum value with respect to the distance (Xmax - Xmin) is represented by tanθ. The edge ring FR of the first to fourth embodiments is configured such that tanθ (= (Hmax - Hmin) / (Xmax - Xmin)) is 9 / 210 or more and 37 / 210 or less.

[0083] [Etching Device]

[0084] Finally, refer to Figure 8 to describe an example of the etching device 10 provided with the edge ring FR of the embodiment. Figure 8 FIG. is a schematic cross-sectional view showing an example of the etching device 10 of the embodiment. The etching device 10 of the embodiment etches an etching target film by exposing a wafer W to plasma of a processing gas (etching gas). Thereby, a hole or the like is formed in the etching target film.

[0085] The etching apparatus 10 is a capacitively coupled plasma etching apparatus, including a substantially cylindrical plasma processing chamber 12. The plasma processing chamber 12 is made of, for example, aluminum whose surface has been anodized. The plasma processing chamber 12 is safely grounded.

[0086] Above the bottom of the plasma processing chamber 12, a cylindrical annular member 15 made of an insulating material is disposed. The annular member 15 supports the susceptor 16 on its inner wall surface. An annular assembly 14 is disposed above the annular member 15. The susceptor 16 is made of a metal such as aluminum and has a substantially disk shape.

[0087] The susceptor 16 is connected to a first high-frequency power supply HFS via a matcher MU1. The first high-frequency power supply HFS is a power supply for generating high-frequency power for plasma generation, generates a frequency in the range of 27 MHz to 100 MHz, and in one example, generates a high frequency of 100 MHz. The matcher MU1 has a circuit for matching the output impedance of the first high-frequency power supply HFS with the input impedance of the load side (the susceptor 16 side).

[0088] In addition, the susceptor 16 is connected to a second high-frequency power supply LFS via a matcher MU2. The second high-frequency power supply LFS generates high-frequency power (high-frequency bias power) for introducing ions into the wafer W and supplies the high-frequency bias power to the susceptor 16. The frequency of the high-frequency bias power is a frequency in the range of 400 kHz to 13.56 MHz, and in one example, is 3.2 MHz. The matcher MU2 has a circuit for matching the output impedance of the second high-frequency power supply LFS with the input impedance of the load side (the susceptor 16 side).

[0089] However, the first high-frequency power supply HFS and the second high-frequency power supply LFS are not limited to the structure connected to the susceptor 16 (lower electrode). It may also be a structure in which the first high-frequency power supply HFS is connected to an upper electrode 30 described later and the second high-frequency power supply LFS is connected to the lower electrode.

[0090] An electrostatic chuck 18 is provided on the susceptor 16. The substrate support portion ST includes a lower electrode and the electrostatic chuck 18. The electrostatic chuck 18 and the susceptor 16 together constitute a mounting table for supporting the wafer W. The electrostatic chuck 18 has a structure in which an electrode 20 as a conductive film is disposed between a pair of insulating layers or insulating sheets. The electrode 20 is electrically connected to a DC power supply 22. The electrostatic chuck 18 can adsorb and hold the wafer W by an electrostatic force such as a Coulomb force generated by a DC voltage from the DC power supply 22.

[0091] The focusing ring FR of the present disclosure is disposed on the upper surface of the susceptor 16 and around the electrostatic chuck 18. In Figure 8 shows schematically the shape of the focusing ring FR.

[0092] A flow path 24 is provided inside the chuck 16. A temperature-controlled medium, such as cooling water, at a specified temperature is circulated and supplied to the flow path 24 from a cooling unit provided outside via pipes 26a and 26b. By controlling the temperature of the temperature-controlled medium circulated in this way, the temperature of the wafer W placed on the electrostatic chuck 18 is controlled.

[0093] In addition, a gas supply line 28 is provided in the etching apparatus 10. The gas supply line 28 supplies a heat transfer gas, such as He gas, from a heat transfer gas supply mechanism between the upper surface of the electrostatic chuck 18 and the back surface of the wafer W.

[0094] In addition, the etching apparatus 10 includes an upper electrode 30. The upper electrode 30 is disposed opposite to the chuck 16 above the chuck 16, and the chuck 16 and the upper electrode 30 are arranged substantially parallel to each other. A processing space S for plasma etching the wafer W is defined between the upper electrode 30 and the chuck 16.

[0095] The upper electrode 30 is supported by an insulating shielding member 32 at the upper part of the plasma processing chamber 12. The upper electrode 30 can include an electrode plate 34 and an electrode support 36. The electrode plate 34 faces the processing space S, and a plurality of gas ejection holes 34a are defined in the electrode plate 34. The electrode plate 34 can be made of a low-resistance conductor or semiconductor with less Joule heat.

[0096] The electrode support 36 is used to support the electrode plate 34 in a detachable manner and can be made of a conductive material such as aluminum, for example. The electrode support 36 can have a water-cooling structure. A gas diffusion chamber 36a is provided inside the electrode support 36. A plurality of gas flow holes 36b communicating with the gas ejection holes 34a extend downward from the gas diffusion chamber 36a. In addition, a gas inlet 36c for guiding the processing gas to the gas diffusion chamber 36a is formed in the electrode support 36, and a gas supply pipe 38 is connected to the gas inlet 36c.

[0097] A gas source group 40 is connected to the gas supply pipe 38 via a valve group 42 and a flow controller group 44. The gas source group 40 includes a plurality of gas sources. The flow controller group 44 includes a plurality of flow controllers, and these plurality of flow controllers can be mass flow controllers respectively. The valve group 42 includes a plurality of valves, and these plurality of valves are respectively connected to the respective flow controllers.

[0098] In the etching apparatus 10, the gas from the selected gas source among the gas sources is supplied to the gas supply pipe 38 in a state where the flow rate is controlled via the corresponding flow controller and valve. The gas supplied to the gas supply pipe 38 reaches the gas diffusion chamber 36a and is ejected into the processing space S via the gas flow holes 36b and the gas ejection holes 34a.

[0099] In addition, the etching apparatus 10 may further include a ground conductor 12a. The ground conductor 12a is a substantially cylindrical ground conductor, and is disposed so as to extend from the side wall of the plasma processing chamber 12 to a position above the height position of the upper electrode 30.

[0100] In addition, in the etching apparatus 10, a deposit shield 46 is detachably provided along the inner wall of the plasma processing chamber 12. Further, the deposit shield 46 is also provided on the outer periphery of the annular member 15. The deposit shield 46 is used to prevent etching by-products (deposits) from adhering to the plasma processing chamber 12, and the deposit shield 46 can be formed by covering ceramics such as Y2O3 with aluminum.

[0101] On the bottom side of the plasma processing chamber 12, an exhaust plate 48 is provided between the inner wall of the plasma processing chamber 12 and the annular member 15. The exhaust plate 48 can be formed, for example, by covering ceramics such as Y2O3 with aluminum. Below the exhaust plate 48, an exhaust port 12e is provided in the plasma processing chamber 12. An exhaust device 50 is connected to the exhaust port 12e via an exhaust pipe 52. The exhaust device 50 includes a vacuum pump such as a turbo molecular pump, and can reduce the pressure in the plasma processing chamber 12 to a desired vacuum level. In addition, a loading / unloading port 12g for the wafer W is provided on the side wall of the plasma processing chamber 12, and the loading / unloading port 12g can be opened and closed by a gate valve 54.

[0102] In addition, a conductive member (GND module) 56 is provided on the inner wall of the plasma processing chamber 12. The conductive member 56 is mounted on the inner wall of the plasma processing chamber 12 so as to be at substantially the same height as the wafer W in the height direction. The conductive member 56 is directly grounded and has the effect of preventing abnormal discharge.

[0103] In addition, the etching apparatus 10 may further include a control unit Cnt. The control unit Cnt is a computer including a processor, a storage unit, an input device, a display device, etc., and controls each part of the etching apparatus 10. In the control unit Cnt, an operator can perform input operations of commands and the like using the input device to manage the etching apparatus 10. In addition, the operating status of the etching apparatus 10 can be visually displayed using the display device. Moreover, a control program for controlling various processes executed by the etching apparatus 10 using the processor and a process recipe for causing each structural part of the etching apparatus 10 to execute a process according to process conditions are stored in the storage unit of the control unit Cnt.

[0104] The edge ring FR of the embodiment can be disposed in the etching apparatus 10. Structures other than those near the edge ring FR of the plasma processing apparatus (etching apparatus) can be used, for example Figure 8The device described in Japanese Patent Application Laid-Open No. 2015-41624 (corresponding to US2015056808.A1). However, the present disclosure is not limited thereto, and the etching device 10 of the present disclosure can also be applied to any type of device among Inductively Coupled Plasma (ICP), Radial Line Slot Antenna (RLSA), Electron Cyclotron Resonance Plasma (ECR), and Helicon Wave Plasma (HWP).

[0105] As described above, according to the edge ring FR and the etching device 10 of the present disclosure, the electric field strength of the outer peripheral portion of the edge ring FR is relatively increased compared to the electric field strength of the inner peripheral portion of the edge ring FR that is closer to the edge region of the wafer W. As a result, the electric field strength of the inner peripheral portion of the edge ring FR is relatively decreased. As a result, in the inner peripheral portion where the electric field strength of the edge ring FR is relatively low, the ion energy is reduced, and the consumption rate of the edge ring FR is decreased. Specifically, by making the outer peripheral portion of the edge ring FR thicker than the inner peripheral portion of the edge ring FR, it is possible to suppress the consumption of the inner peripheral portion of the edge ring FR located near the wafer W and improve the tilt controllability.

[0106] In addition, the disclosed embodiment also includes the following appended forms.

[0107] (Appended Note 1) An edge ring that surrounds the outer periphery of an object to be etched supported by a substrate support portion in a plasma processing chamber, wherein

[0108] the edge ring has an inclined surface that becomes lower from the outer peripheral portion toward the inner peripheral portion,

[0109] the thickness of the edge ring before plasma processing at a location Xa on the inclined surface that is closer to the inner peripheral portion than a midline equidistant from the innermost and outermost peripheries of the edge ring is set as T1,

[0110] the thickness of the edge ring before plasma processing at a location Xb on the inclined surface that is closer to the outer periphery than the midline is set as T2,

[0111] the thickness of the edge ring after plasma processing at the location Xa is set as T3,

[0112] the thickness of the edge ring after plasma processing at the location Xb is set as T4, and at this time,

[0113] the relationship of (T1 - T3) < (T2 - T4) is satisfied.

[0114] (Supplementary Note 2) Regarding the edge ring described in (Supplementary Note 1), the angle of the inclined surface with respect to the horizontal plane is 3° to 7°.

[0115] It should be considered that the edge ring and the etching device of the embodiments disclosed this time are illustrative in all aspects and not restrictive. The embodiments can be deformed and improved in various forms without departing from the scope of the claims and their gist. The matters described in the above-mentioned multiple embodiments can also adopt other structures within the range without causing contradictions, and can be combined within the range without causing contradictions.

Claims

1. An edge ring that surrounds the outer periphery of an object to be etched supported by a substrate support portion within a plasma processing chamber, wherein the edge ring has an inclined surface that becomes lower from the outer peripheral portion toward the inner peripheral portion, the thickness of the edge ring before plasma processing at a location Xa on the inclined surface that is closer to the inner peripheral portion than the intermediate line that is equidistant from the innermost and outermost peripheries of the edge ring is defined as T1, the thickness of the edge ring before plasma processing at a location Xb on the inclined surface that is closer to the outer peripheral portion than the intermediate line is defined as T2, the thickness of the edge ring after plasma processing at the location Xa is defined as T3, the thickness of the edge ring after plasma processing at the location Xb is defined as T4, and at this time, the relationship T2 / T1 > T4 / T3 is satisfied.

2. The edge ring according to claim 1, wherein the edge ring before plasma processing is an edge ring not used within the etching apparatus, the edge ring after plasma processing is an edge ring that has been used up within the etching apparatus.

3. The edge ring according to claim 1 or 2, wherein part or all of the outer side of the stepped portion on the upper surface of the edge ring is an inclined surface.

4. The edge ring according to claim 1 or 2, wherein the edge ring is formed of Si or SiC.

5. The edge ring according to claim 1 or 2, wherein the object to be etched is held above the substrate support portion, the end portion of the object to be etched is configured to protrude outward beyond the inner peripheral side surface of the edge ring, the inclined surface is located at a position outside the end portion of the object to be etched.

6. An etching apparatus having: a plasma processing chamber; a substrate support portion disposed within the plasma processing chamber; and an edge ring that surrounds the outer periphery of an object to be etched supported by the substrate support portion, wherein the edge ring has an inclined surface that becomes lower from the outer peripheral portion toward the inner peripheral portion, the thickness of the edge ring before plasma processing at a location Xa on the inclined surface that is closer to the inner peripheral portion than the intermediate line that is equidistant from the innermost and outermost peripheries of the edge ring is defined as T1, the thickness of the edge ring before plasma processing at a location Xb on the inclined surface that is closer to the outer peripheral portion than the intermediate line is defined as T2, the thickness of the edge ring after plasma processing at the location Xa is defined as T3, the thickness of the edge ring after plasma processing at the location Xb is defined as T4, and at this time, the relationship T2 / T1 > T4 / T3 is satisfied.

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