Edge ring and etching equipment

Abstract

To provide an edge ring capable of suppressing exhaustion of an internal peripheral part of the edge ring.SOLUTION: A present invention provides an edge ring surrounding an outer periphery of an etched material supported by a substrate support part in a plasma processing chamber, in which the edge ring includes an inclination surface that becomes lower toward an inner peripheral part from the outer peripheral part, and when a thickness of the edge ring before a plasma processing at a point Xa positioned on the inclination surface of the inner peripheral part from an intermediate line existed in an equidistance from the innermost periphery and the outermost periphery of the edge ring is T1, a thickness of the edge ring before the plasma processing at a point Xb positioned on an upside of the inclination surface of the outer periphery from the intermediate line is T2, a thickness of the edge ring after the plasma processing at the point Xa is T3, and a thickness of the edge ring after the plasma processing at the point Xb is T4, the following equation of T2 / T1>T4 / T3 are satisfied.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] Plasma processing such as etching causes wear of the edge ring, which is a component located near the substrate. When the thickness of the edge ring decreases due to wear, the shape of the sheath above the edge ring changes, and the incident direction of ions from the plasma on the edge region of the substrate tilts inward from the vertical direction (hereinafter also referred to as "tilt"). As a result, the in-plane uniformity of the plasma processing is impaired. Since wear of the inner periphery of the edge ring close to the edge region of the substrate has a significant effect on the tilt, an edge ring that can suppress wear of the inner periphery is desired. The edge ring is also called a focus ring.

[0003] For example, Patent Document 1 provides a plasma processing method that minimizes adverse effects on processing results such as etching shapes caused by wear of the focus ring and enables the use period of the focus ring to be extended. In Patent Document 1, a DC power supply is connected to the focus ring, and a predetermined DC voltage is applied to the focus ring based on the degree of wear of the focus ring, the detection result of the change in the electric field above the focus ring, or the result of a plasma processing that has already been performed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-258417 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure provides an edge ring that can suppress wear of the inner periphery of the edge ring. [Means for solving the problem]

[0006] According to one aspect of the present disclosure, there is provided an edge ring surrounding an outer periphery of an object to be etched supported by a substrate support in a plasma processing chamber, the edge ring having an inclined surface that becomes lower from an outer periphery toward an inner periphery, a thickness of the edge ring before plasma processing at a point Xa located on the inclined surface of the inner periphery of the edge ring relative to a midline that is equidistant from the innermost and outermost peripheries of the edge ring is defined as T1, Department When the thickness of the edge ring before plasma treatment at a point Xb located on the inclined surface is T2, the thickness of the edge ring after plasma treatment at the point Xa is T3, and the thickness of the edge ring after plasma treatment at the point Xb is T4, an edge ring is provided which satisfies the relationship T2 / T1>T4 / T3. Effect of the Invention

[0007] According to one aspect, an edge ring capable of suppressing wear of an inner periphery of the edge ring can be provided. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1A is a diagram showing an edge ring according to a reference example, and FIG. 1B is a diagram showing an edge ring according to an embodiment. [Diagram 2] FIG. 2 is a diagram illustrating an example of the periphery of an edge ring according to an embodiment. [Diagram 3] FIG. 3 is a graph showing the electric field intensity of the edge ring in the embodiment and the reference example. [Figure 4] 4(a) and (b) are graphs showing the correlation between the electric field intensity ratio and the wear rate ratio of the edge ring at the inner periphery relative to the outer periphery in the embodiment and the reference example. [Diagram 5] FIG. 5 is a plan view showing the edge ring according to the first embodiment. [Figure 6] FIG. 6 is a cross-sectional view (cross-sectional view taken along line AA in FIG. 5) showing the edge ring according to the first embodiment. [Figure 7] FIG. 7 is a cross-sectional view showing the edge ring according to the second to fourth embodiments. [Figure 8] FIG. 8 is a schematic cross-sectional view showing an example of an etching apparatus according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In each drawing, the same components are denoted by the same reference numerals, and the description thereof may be omitted.

[0010] [Edge Ring] First, an edge ring FR according to an embodiment will be described with reference to Fig. 1 and Fig. 2. Fig. 1(a) is a diagram showing an edge ring FR' according to a reference example, and Fig. 1(b) is a diagram showing an edge ring FR according to an embodiment. Fig. 2 is a diagram showing an example of the edge ring FR according to the embodiment and its periphery.

[0011] The edge ring FR is an annular member arranged to surround the outer periphery of a substrate (hereinafter referred to as "wafer W"), which is an example of an object to be etched, supported by a substrate support ST in a plasma processing chamber 12 of an etching apparatus 10 (see FIG. 8). In one example, the edge ring FR is made of a conductive material such as Si or SiC. The cover ring 14a is an annular member arranged to surround the outer periphery of the edge ring FR. In one example, the cover ring 14a is made of an insulating material such as quartz. The etching apparatus 10 is an apparatus that performs plasma processing (etching) on ​​an object to be etched (film to be etched) on the wafer W. The substrate support ST includes a base 16 and an electrostatic chuck 18. Other components of the etching apparatus 10 will be described later.

[0012] An edge ring FR' according to a reference example in Fig. 1(a) and an edge ring FR (hereinafter also referred to as Taper FR) according to an embodiment in Fig. 1(b) will be described. The edge ring FR' according to the reference example and the edge ring FR according to the embodiment have different shapes of the upper surface, but the other shapes are the same.

[0013] 1A shows an edge ring FR' according to a reference example, and its longitudinal section is a surface surrounded by cutting lines when the edge ring FR' is cut in the radial direction through an inner peripheral side surface 160b, an outer peripheral side surface 160d, a bottom surface 160e connecting the lower ends of the inner peripheral side surface 160b and the outer peripheral side surface 160d, and an 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' is composed of a surface 160a1, a surface 160a2, and a step portion 160c.

[0014] The vertical cross section of the edge ring FR according to the embodiment shown in FIG. 1(b) is a surface surrounded by the cut lines when the edge ring FR is cut in the radial direction through the inner peripheral side surface 60b, the outer peripheral side surface 60d, the bottom surface 60e connecting the lower ends of the inner peripheral side surface 60b and the outer peripheral side surface 60d, and the top surface 60a connecting the upper ends of the inner peripheral side surface 60b and the outer peripheral side surface 60d. The top surface 60a of the edge ring FR is composed of a surface 60a1, a surface 60a2, a surface 60a3, and a step portion 60c. Note that, with respect to an 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 of the edge ring FR (FR inner peripheral portion) and the outer region of the edge ring FR (FR outer peripheral portion) are defined as the inner peripheral portion of the edge ring FR. Similarly, with respect to an unillustrated midline that is equidistant horizontally from the inner peripheral side surface 160b and the outer peripheral side surface 160d of the edge ring FR, the inner region of the edge ring FR is defined as the inner peripheral portion of the edge ring FR (FR inner peripheral portion), and the outer region of the edge ring FR is defined as the outer peripheral portion of the edge ring FR (FR outer peripheral portion).

[0015] In the edge ring FR' supported by the base 16 or the annular member 15, the surfaces 160a1 and 160a2 of the upper surface 160a are horizontal surfaces. In the edge ring FR supported by the base 16 or the annular member 15, the surfaces 60a2 and 60a3 of the upper surface 60a are horizontal surfaces, and the surface 60a1 is an inclined surface that becomes lower from the outer periphery toward the inner periphery of the edge ring FR. The bottom surface 160e, the surfaces 160a1 and 160a2 are substantially parallel surfaces. Similarly, the bottom surface 60e, the surfaces 60a2 and 60a3 are substantially parallel surfaces. In this specification, the above-mentioned surfaces being "horizontal surfaces" means that when the edge rings FR' and FR are placed on the ring support surface 16b of the base 16, the surfaces 160a1 and 160a2, and the surfaces 60a2 and 60a3 become horizontal surfaces. Similarly, in this specification, the term "inclined surface" means that when the edge ring FR is placed on the ring support surface 16b of the base 16, the surface 60a1 becomes an inclined surface that becomes lower from the outer periphery toward the inner periphery.

[0016] 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, 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 disposed on the central support surface 16a of the base 16, and the edge rings FR, FR' are disposed on the ring support surface 16b of the base 16.

[0017] 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 on the substrate support surface 18a. The edge rings FR, FR' are disposed to surround the wafer W on the electrostatic chuck 18.

[0018] 2, the ring assembly 14 is composed of 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 made of an insulator such as quartz. The annular member 15 is configured to surround the outer periphery of a base 16.

[0019] The height (thickness) of the outermost periphery of the edge ring FR and the height (thickness) of the innermost periphery of the cover ring 14a are substantially the same. In other words, there is no step between the outermost periphery top surface of the edge ring FR and at least the innermost periphery top surface of the cover ring 14a. The outer periphery of the bottom surface of the cover ring 14a protrudes downward in a ring shape below the inner periphery, and is engaged with a ring-shaped recess formed on the outer periphery side of the top surface of the annular member 15. The edge ring FR may be placed on the ring support surface 16b of the base 16 via a heat transfer sheet.

[0020] Returning to FIG. 1, the edge rings FR, FR' are configured so that the edge of the wafer W extends outward beyond the inner peripheral side surfaces 60b, 160b of the edge rings FR, FR'. A step portion 60c, 160c is formed on the upper surface 60a, 160a of the edge rings FR, FR' near the edge of the wafer W and outside the edge of the wafer W. Surfaces 60a3, 160a2 of the upper surfaces 60a, 160a of the edge rings FR, FR' from the innermost periphery to the step portion 60c, 160c are flat horizontal surfaces. Hereinafter, the surface 60a3 will be referred to as the first surface.

[0021] In the edge ring FR' of the reference example in FIG. 1(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', and the surface 160a2 has a width of about 1 to 2 mm from the upper end of the inner side surface 160b. The thickness of the edge ring FR' from the inner side surface 160b of the edge ring FR' to the step portion 160c is the same. Also, the thickness 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 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 edge ring FR' from the inner side surface 160b of the edge ring FR' to the step portion 160c. In other words, the height of a surface 160a1 on the outer circumferential side of the step portion 160c is higher than the height of a surface 160a2 on the inner circumferential side of the step portion 160c.

[0022] In contrast, in the edge ring FR of the embodiment of FIG. 1(b), the upper surface 60a is composed of 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 toward the outer peripheral side of the step portion 60c, and a second surface 60a2, and 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 horizontal surfaces when placed on the ring support surface 16b of the base 16, and the thickness of the edge ring FR from the inner peripheral side surface 60b to the step portion 60c is the same. The second surface 60a2 may be a horizontal surface or an inclined surface when placed on the ring support surface 16b of the base 16. The inclined surface 60a1 is a surface between the first surface 60a3 and the second surface 60a2. The first surface 60a3, the second surface 60a2, and the inclined surface 60a1 are flat. The thickness of the edge ring FR on the outer side of the step portion 60c is thinner at the inner peripheral portion of the inclined surface 60a1 and thicker at the outer peripheral portion than the thickness of the edge ring FR on the inner side of the step portion 60c.

[0023] With this configuration, the edge ring FR' of the reference example in Fig. 1(a) has a constant thickness on the outer circumferential side of the step portion 160c. In contrast, in the edge ring FR of the embodiment in Fig. 1(b), the thickness of the edge ring FR on the outer circumferential side of the step portion 60c becomes thicker toward the outside (inclined surface 60a1).

[0024] As a result, the thickness from the inner peripheral side surface 60b, 160b of the edge ring FR, FR' to the step portion 60c, 160c is the same for each edge ring FR, FR', but the relative height from the upper surface of the wafer W outside the step portion 60c, 160c is different between the edge ring FR and the edge ring FR'. That is, in the edge ring FR' of the reference example in FIG. 1(a), the upper surface 160a is a horizontal plane even outside the step portion 160c, so the relative height of the upper surface 160a from the upper surface of the wafer W is the same. In contrast, in the edge ring FR of the embodiment in FIG. 1(b), the relative height from the upper surface of the wafer W at least the inclined surface 60a1 of the upper surface 60a outside the step portion 60c decreases from the outer peripheral portion toward the inner peripheral portion.

[0025] As described later, high frequency power is applied to the edge rings FR, FR' from the first high frequency power supply HFS and / or the second high frequency power supply LFS to the base 16 (see FIG. 8), and a high frequency current (RF current) flows through the edge rings FR, FR'.

[0026] Under the same conditions, the electric field strength in the sheath formed on the edge rings FR, FR' by the high-frequency current is constant overall, and for example, the electric field strength cannot be made 0. By changing the height of the upper faces 60a, 160a on the outer periphery side of the step portions 60c, 160c of the edge rings FR, FR', the electric field strengths in the outer periphery and inner periphery can be changed relatively.

[0027] For example, in the edge ring FR' of the reference example, the relative height of the upper surface 160a outside the step portion 160c from the upper surface of the wafer W is the same. Therefore, the ratio of the high frequency current flowing through the surface layer of the edge ring FR' is approximately the same at the outer circumferential portion and the inner circumferential portion. As a result, the electric field intensity in the sheath is also approximately the same at the outer circumferential portion and the inner circumferential portion.

[0028] On the other hand, in the edge ring FR of the embodiment, the inner peripheral portion of the inclined surface 60a1 has a lower relative height from the upper surface of the wafer W than the outer peripheral portion. 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 FR in the sheath becomes higher than the electric field strength of the inner peripheral portion of the FR.

[0029] The graph in Figure 3 shows the simulation results in which the electric field strength (vertical axis) generated by the high-frequency current flowing through the edge rings FR, FR' under the following conditions is plotted against the radial position of the edge rings FR, FR' on the horizontal axis: 150 mm on the graph is the position of edge A of the wafer W, which is located at a radius of 150 mm from the center of the wafer W, and 180 mm is the position of edge B of the edge rings FR, FR', which is located at a radius of 180 mm from the center of the wafer W (see Figures 1(a) and (b)). <Simulation conditions> Angle (inclination angle) of the inclined surface 60a1 of the edge ring FR with respect to the horizontal plane: 3° Angle of surface 160a1 of edge ring FR' with respect to the horizontal plane: 0° Etching gas: A mixture of C4F6 gas, O2 gas and Ar gas Pressure: 50mTorr (6.67Pa) RF (HF) output from the first high frequency power supply HFS: 100MHz RF (LF) output from the second high frequency power supply LFS: 3.2MHz The RF (HF): 100 MHz output from the first high frequency power supply HFS and the RF (LF): 3.2 MHz output from the second high frequency power supply LFS were set to be supplied to the lower electrode.

[0030] Curve S in the graph of Fig. 3 indicates the electric field intensity at each position in the radial direction of the edge ring FR' of the reference example shown in Fig. 1(a) from end A of the wafer W to end B of the edge ring FR'. In curve S, the electric field intensity is approximately constant in the range from approximately 153 mm to approximately 175 mm from the center of the wafer W in the radial direction on the outer circumferential side of step portion 160c at approximately 153 mm.

[0031] Curve T in the graph of Fig. 3 indicates the electric field intensity at each position in the radial direction of the edge ring FR (Taper FR) of the embodiment shown in Fig. 1(b). In curve T, on the outer periphery side of step portion 60c at about 153 mm, highs and lows occur in the electric field intensity at the outer periphery and the electric field intensity at the inner periphery in the range of about 153 mm to about 175 mm from the center of the wafer W in the radial direction. In particular, in the edge ring FR, the electric field intensity at the inner periphery is lower than that of the edge ring FR' in the range of about 153 mm to about 160 mm from the center of the wafer W, and the electric field intensity at the outer periphery is higher in the range of about 170 mm to about 180 mm.

[0032] From the above results, in the edge ring FR according to the embodiment, the upper surface 60a has an inclined surface 60a1 such that the inner circumference is lower than the outer circumference in the radial direction, so that the electric field strength of the outer circumference of the FR in the sheath can be made higher than the electric field strength of the inner circumference of the FR in the radial direction of the edge ring FR. That is, as shown in FIG. 1(b), the edge ring FR can make the electric field strength of the inner circumference relatively smaller than the electric field strength of the outer circumference by the inclined surface 60a1 that becomes lower from the outer circumference of the FR toward the inner circumference of the FR. As a result, the energy of ions entering the sheath is smaller in the inner circumference of the FR, where the electric field strength is relatively low, than in the outer circumference of the FR, where the electric field strength is relatively high. As a result, the wear rate of the edge ring FR can be made lower in the inner circumference of the FR than in the outer circumference of the FR.

[0033] 1B, the edge ring FR according to the embodiment has a structure in which the upper surface 60a is inclined so that the inner periphery is lower than the outer periphery, thereby generating an electric field strength difference between the outer periphery and the inner periphery of the edge ring FR. This makes it possible to intentionally control the wear rate of the edge ring FR.

[0034] As shown in Fig. 2 as an example of positions Xa and Xb, position Xa on the upper surface 60a located on the inner periphery with respect to the midpoint Ax is relatively lower than position Xb on the upper surface 60a located on the outer periphery with respect to the midpoint Ax. For example, in the edge ring FR according to the embodiment shown by curve T in the graph of Fig. 3, the electric field intensity can be relatively lower at position Xa on the inner periphery (e.g., about 153 mm from the center of the wafer W) than at position Xb on the outer periphery (e.g., about 176 mm from the center of the wafer W). On the other hand, in the edge ring FR' according to the reference example shown by curve S in the graph of Fig. 3, the electric field intensity is approximately the same at position Xa on the inner periphery and position Xb on the outer periphery.

[0035] Next, an experiment was carried out on the wear of the edge ring FR'FR under the following experimental conditions. <Experimental conditions> Angle (inclination angle) of the inclined surface 60a1 of the edge ring FR with respect to the horizontal plane: 3° Angle of surface 160a1 of edge ring FR' with respect to the horizontal plane: 0° Material to be etched (film to be etched): SiO2 Etching gas: A mixture of C4F6 gas, O2 gas and Ar gas In this experiment, the substrate W was etched for a cumulative period of 200 hours.

[0036] As a result of the experiment, when the wear rate of the edge ring FR' was normalized to 1, the wear rate ratio of the edge ring FR to the wear rate of the edge ring FR' was about 0.6 times at a position 3 mm from the innermost circumference of the edge ring FR', FR, i.e., at a position 153 mm from the center of the wafer W, and was about 0.9 times at a position 4 mm from the outermost circumference of the edge ring FR', FR, i.e., at a position 176 mm from the center of the wafer W. Among the above <experimental conditions>, when the inclination angle θ of the inclined surface of the edge ring FR with respect to the horizontal plane was set to 7° and the other conditions were the same, the ratio of the wear rate of the edge ring FR to the wear rate of the edge ring FR' was about 0.5 times at the inner circumference and about 1.0 times at the outer circumference. In either case, the wear amount (wear rate) of the inner circumference was smaller than the wear amount (wear rate) of the outer circumference.

[0037] In the edge ring FR according to the embodiment, the height of the outer periphery of the upper surface is made higher than the height of the inner periphery. This makes it possible to reduce the wear amount (change amount) of the inner periphery near the wafer W compared to the edge ring FR' of the reference example having the same flat upper surface height. That is, according to the edge ring FR according to the embodiment, the wear rate of the edge ring FR can be made lower at the inner periphery of FR than at the outer periphery of FR. That is, when the thickness of the edge ring FR before plasma processing at the point Xa is T1, the thickness of the edge ring FR before plasma processing at the point Xb on the upper surface 60a located on the inclined surface 60a1 of the outer periphery from the middle line Ax is T2, the thickness of the edge ring FR after plasma processing at the point Xa is T3, and the thickness of the edge ring FR after plasma processing at the point Xb is T4, the wear amount (wear rate) of the inner periphery can be expressed as T1-T3 and the wear amount (wear rate) of the outer periphery can be expressed as T2-T4, and the relationship (T1-T3)<(T2-T4) is established. In addition, tilt is suppressed, enabling vertical etching even at the edge of the wafer W. This improves the in-plane etching uniformity. In addition, intentionally controlling the wear rate of the edge ring FR extends the life of the edge ring FR, which also has cost benefits. Furthermore, the variation in the amount of tilt between the nth (n≧1)th wafer W and the n+1th wafer W can be improved.

[0038] 4(a) and (b) show the correlation between the simulation results shown in FIG. 3 and the above experimental results using an edge ring FR according to an embodiment in which only the inclined surface 60a1 of the upper surface 60a shown in FIG. 1(b) is inclined and the second surface 60a2 is a horizontal surface, and an edge ring FR' of a reference example in which the upper surface 160a shown in FIG. 1(a) is flat.

[0039] FIG. 4(a) is a graph showing the correlation between the simulation results (FIG. 3) of the electric field strength ratio between the inner and outer peripheries of the electric field strength generated by the high-frequency current flowing through the edge rings FR and FR', with the horizontal axis showing the electric field strength ratio at the inner and outer peripheries being the electric field strength ratio at the outer peripheries and the wear rate ratio being the vertical axis. The inner periphery is located 153 mm from the center of the wafer W, and the outer periphery is located 176 mm from the center of the wafer W. The wear amount at the outer periphery of the edge ring FR' of the reference example shown in FIG. 1(a) is standardized to a wear rate ratio of "1," and the electric field strength at the outer periphery of the edge ring FR' is standardized to an electric field strength ratio of "1." F1-inner indicates the inner periphery of the edge ring FR', F1-outer indicates the outer periphery of the edge ring FR', T1-inner indicates the inner periphery of the edge ring FR, and T1-outer indicates the outer periphery of the edge ring FR.

[0040] As shown in Figures 4(a) and (b), in the edge ring FR' of the reference example, the electric field strength ratio and wear rate ratio of the inner circumference (F1-inner) to the outer circumference (F1-outer) were almost the same. In contrast, in the edge ring FR of the embodiment, the electric field strength of the outer circumference (T1-outer) was the same as that of the outer circumference (F1-outer) of the edge ring FR', but the electric field strength ratio of the inner circumference (T1-inner) of the edge ring FR to the outer circumference (F1-outer) of the edge ring FR' and the outer circumference (T1-outer) of the edge ring FR was about 0.7 times. The wear rate ratio of the edge ring FR of the embodiment was 0.9 times at the outer circumference (T1-outer) to the outer circumference (F1-outer) of the edge ring FR', and 0.6 times at the inner circumference (T1-inner) to the outer circumference (F1-outer) of the edge ring FR'. That is, in the edge ring FR, the wear rate ratio decreased as the relative height ratio of the edge ring FR from the wafer W decreased. Also, in the edge ring FR, the relative height of the inner portion of the edge ring FR from the wafer W was lower than that of the outer portion, and the electric field strength ratio of the inner portion to the outer portion of the edge ring FR decreased, resulting in a decrease in the wear rate ratio. From the above, it is possible to change the electric field strength ratio and wear rate ratio of the inner portion to the outer portion by changing the relative height ratio of the edge ring FR from the wafer W, thereby enabling the amount of wear in the inner portion of the edge ring FR to be reduced.

[0041] [First to fourth embodiments of edge ring] (First embodiment) Next, the edge ring FR according to the first embodiment will be described with reference to Fig. 5 and Fig. 6. Fig. 5 is a plan view showing the edge ring FR according to the first embodiment. Fig. 6 is a cross-sectional view (cross-sectional view taken along line AA in Fig. 5) showing the edge ring FR according to the first embodiment.

[0042] 5, in the first embodiment, an edge ring FR is disposed so as to surround the outer periphery of a wafer W having a radius of approximately 150 mm. The edge ring FR is disposed generally concentrically with the central axis O of the wafer W.

[0043] The inner diameter I of the edge ring FR is about 300 mm to about 305 mm, the outer diameter J of the edge ring FR is about 360 mm to 365 mm, and the radial width C of the edge ring FR is about 28 mm to 32 mm. The radial width E of the edge ring FR from the innermost circumference to the step portion 60c may be about 1 mm or more and about 2 mm or less.

[0044] The upper surface 60a of the edge ring FR has an inclined surface 60a1 and a second surface 60a2 on the outside of the step portion 60c. The upper surface 60a of the edge ring FR has a first surface 60a3 on the inside of the step portion 60c. The first surface 60a3, the inclined surface 60a1, and the second surface 60a2 are flat. The upper surface 60a may be partially inclined or entirely inclined. In other words, the second surface 60a2 may be an inclined surface or a horizontal surface. In the example of FIG. 6 showing the AA cross section of FIG. 5, the second surface 60a2 is a horizontal surface.

[0045] The second surface 60a2 has a width G of about 5 mm or more and about 7 mm or less in the radial direction from the outermost circumference of the edge ring FR to the inside. The radial width of the inclined surface 60a1 may be about 20 mm or more and about 30 mm or less. In the present disclosure, the inclined surface 60a1 may be a flat surface that uniformly decreases from the outer circumference to the inner circumference such that the inclination angle θ (°) with respect to the horizontal plane is 2.5° or more and 10° or less. If the inclination angle θ (°) is less than 2.5°, the effect of reducing wear of the inner circumference of the FR is not sufficient, and if it exceeds 10°, there is a risk that the in-plane uniformity at the beginning of the substrate processing (before the outer circumference of the edge ring is worn) will deteriorate (it becomes difficult to suppress tilt). If the angle is large, the distortion of the lower end of the sheath becomes large, making it difficult to control the tilt (tilt toward the outside of the substrate edge (outer tilt) becomes large). Therefore, it is necessary to set the angle to 10° or less. Considering the two viewpoints of tilt controllability and the degree of reduction in wear of the inner circumference of the edge ring, it is more preferable that the tilt angle θ (°) is 3° or more and 7° or less. That is, by setting the tilt angle θ (°) to 3° or more, the ratio of the high frequency current flowing through the inner circumference of the FR to the high frequency current flowing through the outer circumference of the FR can be further reduced, and the effect of reducing wear in the inner circumference can be sufficiently obtained. In addition, by setting the tilt angle θ (°) to 7° or less, it is possible to prevent the amount of outward tilt (outer tilt) at the edge of the wafer W from becoming large, and vertical etching of the wafer W can be achieved within the plane of the wafer W, including the edge of the wafer W.

[0046] The thickness D of the innermost periphery of the edge ring FR is about 3 mm. The maximum value of the thickness H of the outermost periphery of the edge ring FR is not less than about 3.5 mm and not more than about 7.0 mm. The height F of the step portion 60c is about 0.2 mm.

[0047] 6, the inclined surface 60a1 indicated by the dashed line indicates the height of the edge ring FR before the plasma treatment, and the inclined surface 60a1 indicated by the solid line is an example indicating the height of the edge ring FR after the plasma treatment. The edge ring FR before the plasma treatment may mean an unused (new) edge ring FR. The edge ring FR after the plasma treatment may mean a used edge ring FR, that is, an edge ring FR that has been worn out through the plasma treatment (e.g., at the time of replacement).

[0048] A point on the upper surface 60a located on the inner inclined surface 60a1 relative to the midline Ax that is equidistant horizontally from the innermost and outermost circumferences of the edge ring FR is designated as Xa, and the thickness of the edge ring FR before plasma processing at point Xa is designated as T1. The thickness of the edge ring FR before plasma processing at point Xb on the upper surface 60a located on the outer peripheral inclined surface 60a1 relative to the midline Ax is designated as T2.

[0049] The thickness of the edge ring FR after the plasma processing at the point Xa is T3, and the thickness of the edge ring FR after the plasma processing at the point Xb is T4, where the relationship T2 / T1>T4 / T3 holds.

[0050] (Second to fourth embodiments) Next, an edge ring FR according to second to fourth embodiments will be described with reference to FIG. 7. FIG. 7 is a cross-sectional view showing an edge ring FR according to second to fourth embodiments. The second to fourth embodiments differ from the first embodiment in that the inclined surface 60a1 of the upper surface 60a of the edge ring FR is not a flat surface. The other configurations 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 may be at least one of a flat surface, a concave surface, a convex surface, and a curved surface.

[0051] In the second embodiment shown in Fig. 7(a), the inclined surface 60a1 is concave. In the third embodiment shown in Fig. 7(b), the inclined surface 60a1 is convex. In the fourth embodiment shown in Fig. 7(c), the outer periphery of the inclined surface 60a1 is convex and the inner periphery is concave.

[0052] In the second to fourth embodiments, the radial distance between horizontal positions Xmax and Xmin corresponding to the positions of the inclined surface 60a1 where the height to the inclined surface 60a1 of the edge ring FR is the maximum value Hmax and the minimum value Hmin is defined as (Xmax-Xmin). The difference (Hmax-Hmin) between the maximum and minimum heights for the distance (Xmax-Xmin) is represented by tan θ. The edge ring FR in the first to fourth embodiments is configured such that tan θ (=(Hmax-Hmin) / (Xmax-Xmin)) is 9 / 210 or more and 37 / 210 or less.

[0053] [Etching equipment] Finally, an example of an etching apparatus 10 in which an edge ring FR according to the embodiment is disposed will be described with reference to FIG. 8. FIG. 8 is a schematic cross-sectional view showing an example of the etching apparatus 10 according to the embodiment. The etching apparatus 10 according to the embodiment exposes a wafer W to plasma of a processing gas (etching gas) to etch a film to be etched. As a result, a shape such as a hole is formed in the film to be etched.

[0054] The etching apparatus 10 is a capacitively coupled plasma etching apparatus and includes a substantially cylindrical plasma processing chamber 12. The surface of the plasma processing chamber 12 is made of, for example, aluminum with anodized treatment. The plasma processing chamber 12 is protectively grounded.

[0055] A cylindrical annular member 15 made of an insulating material is disposed on the bottom of the plasma processing chamber 12. The inner wall surface of this annular member 15 supports a base 16. A ring assembly 14 is disposed on the upper part of the annular member 15. The base 16 is made of a metal such as aluminum, and has a generally disk-like shape.

[0056] A first high frequency power supply HFS is connected to the base 16 via a matching unit MU1. The first high frequency power supply HFS is a power supply that generates high frequency power for generating plasma, and generates a high frequency power having a frequency in the range of 27 to 100 MHz, for example, 100 MHz. The matching unit MU1 has a circuit for matching the output impedance of the first high frequency power supply HFS with the input impedance on the load side (base 16 side).

[0057] A second high frequency power supply LFS is also connected to the base 16 via a matching unit MU2. The second high frequency power supply LFS generates high frequency power (high frequency bias power) for attracting ions into the wafer W and supplies the high frequency bias power to the base 16. The frequency of the high frequency bias power is within a range of 400 kHz to 13.56 MHz, and is 3.2 MHz in one example. The matching unit MU2 has a circuit for matching the output impedance of the second high frequency power supply LFS with the input impedance on the load side (base 16 side).

[0058] However, the first high frequency power supply HFS and the second high frequency power supply LFS are not limited to being coupled to the base 16 (lower electrode). The first high frequency power supply HFS may be coupled to an upper electrode 30, which will be described later, and the second high frequency power supply LFS may be coupled to the lower electrode.

[0059] An electrostatic chuck 18 is provided on the base 16. The substrate support part ST includes a lower electrode and the electrostatic chuck 18. The electrostatic chuck 18, together with the base 16, constitutes a mounting table for supporting the wafer W. The electrostatic chuck 18 has a structure in which an electrode 20, which is a conductive film, is disposed between a pair of insulating layers or insulating sheets. A DC power supply 22 is electrically connected to the electrode 20. The electrostatic chuck 18 can attract and hold the wafer W by electrostatic force such as Coulomb force generated by a DC voltage from the DC power supply 22.

[0060] A focus ring FR according to the present disclosure is disposed on the upper surface of base 16 and around electrostatic chuck 18. Fig. 8 shows a schematic shape of focus ring FR.

[0061] A flow path 24 is provided inside the base 16. A temperature control medium, such as cooling water, at a predetermined temperature is circulated and supplied to the flow path 24 from a chiller unit provided outside through pipes 26a and 26b. By controlling the temperature of the temperature control medium circulated in this manner, the temperature of the wafer W placed on the electrostatic chuck 18 is controlled.

[0062] The etching apparatus 10 is also provided with a gas supply line 28. The gas supply line 28 supplies a heat transfer gas, for example, He gas, from a heat transfer gas supply mechanism to between the upper surface of the electrostatic chuck 18 and the back surface of the wafer W.

[0063] The etching apparatus 10 also includes an upper electrode 30. The upper electrode 30 is disposed above the base 16 and faces the base 16, and the base 16 and the upper electrode 30 are disposed approximately parallel to each other. A processing space S for performing plasma etching on the wafer W is defined between the upper electrode 30 and the base 16.

[0064] The upper electrode 30 is supported on the upper part of the plasma processing chamber 12 via an insulating shielding member 32. The upper electrode 30 may include an electrode plate 34 and an electrode support 36. The electrode plate 34 faces the processing space S and defines a plurality of gas ejection holes 34a. The electrode plate 34 may be made of a conductor or semiconductor with low electrical resistance that generates little Joule heat.

[0065] The electrode support 36 detachably supports the electrode plate 34 and may be made of a conductive material such as aluminum. The electrode support 36 may have a water-cooled structure. A gas diffusion chamber 36a is provided inside the electrode support 36. A plurality of gas flow holes 36b that communicate with the gas discharge holes 34a extend downward from the gas diffusion chamber 36a. The electrode support 36 is also formed with a gas inlet 36c that introduces a process gas into the gas diffusion chamber 36a, and a gas supply pipe 38 is connected to the gas inlet 36c.

[0066] A gas source group 40 is connected to the gas supply pipe 38 via a valve group 42 and a flow rate controller group 44. The gas source group 40 includes a plurality of gas sources. The flow rate controller group 44 includes a plurality of flow rate controllers, each of which may be a mass flow controller. The valve group 42 includes a plurality of valves, each of which is connected to a respective flow rate controller.

[0067] In the etching apparatus 10, gas from a selected gas source among the gas sources is supplied to the gas supply pipe 38 at a controlled flow rate via a corresponding flow rate controller and valve. The gas supplied to the gas supply pipe 38 reaches the gas diffusion chamber 36a and is discharged into the processing space S via the gas flow holes 36b and the gas discharge holes 34a.

[0068] The etching apparatus 10 may further include a ground conductor 12a. The ground conductor 12a is a substantially cylindrical ground conductor that is provided to extend from the side wall of the plasma processing chamber 12 to a position above the height of the upper electrode 30.

[0069] Furthermore, in the etching apparatus 10, a deposit shield 46 is detachably provided along the inner wall of the plasma processing chamber 12. The deposit shield 46 is also provided on the outer periphery of the annular member 15. The deposit shield 46 prevents etching by-products (deposits) from adhering to the plasma processing chamber 12, and may be formed by coating an aluminum material with ceramics such as Y2O3.

[0070] An exhaust plate 48 is provided on the bottom side of the plasma processing chamber 12 between the annular member 15 and the inner wall of the plasma processing chamber 12. The exhaust plate 48 can be formed, for example, by coating an aluminum material with ceramics such as Y2O3. An exhaust port 12e is provided in the plasma processing chamber 12 below the exhaust plate 48. An exhaust device 50 is connected to the exhaust port 12e via an exhaust pipe 52. The exhaust device 50 has a vacuum pump such as a turbo molecular pump, and can reduce the pressure inside the plasma processing chamber 12 to a desired vacuum level. In addition, a transfer port 12g for a wafer W is provided on a side wall of the plasma processing chamber 12, and the transfer port 12g can be opened and closed by a gate valve 54.

[0071] Further, a conductive member (GND block) 56 is provided on the inner wall of the plasma processing chamber 12. The conductive member 56 is attached to the inner wall of the plasma processing chamber 12 so as to be located at approximately the same height as the wafer W in the height direction. The conductive member 56 is connected to the ground in a DC manner, and exerts an effect of preventing abnormal discharge.

[0072] 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, and the like, and controls each unit of the etching apparatus 10. In the control unit Cnt, an operator can use the input device to input commands to manage the etching apparatus 10, and the display device can visualize and display the operating status of the etching apparatus 10. Furthermore, the storage unit of the control unit Cnt stores a control program for controlling various processes executed by the etching apparatus 10 using a processor, and a program for causing each component of the etching apparatus 10 to execute a process according to processing conditions, i.e., a processing recipe.

[0073] The edge ring FR of the embodiment can be disposed in an etching apparatus 10. The configuration of the plasma processing apparatus (etching apparatus) other than the configuration near the edge ring FR can be, for example, the apparatus described in Japanese Patent Application Publication No. 2015-41624 (corresponding to US2015056808.A1) shown in FIG. 8. However, the present disclosure is not limited to this, and the etching apparatus 10 can be applied to any type of apparatus, such as an Inductively Coupled Plasma (ICP), a Radial Line Slot Antenna (RLSA), an Electron Cyclotron Resonance Plasma (ECR), or a Helicon Wave Plasma (HWP).

[0074] As described above, according to the edge ring FR and the etching apparatus 10 of the present disclosure, the electric field strength at the outer periphery of the edge ring FR is relatively higher than the electric field strength at the inner periphery of the edge ring FR close to the edge region of the wafer W. This relatively lowers the electric field strength at the inner periphery of the edge ring FR. This reduces the ion energy at the inner periphery of the edge ring FR where the electric field strength is relatively low, and reduces the wear rate of the edge ring FR. Specifically, by making the outer periphery of the edge ring FR thicker than the inner periphery, wear of the inner periphery of the edge ring FR near the wafer W can be suppressed and tilt controllability can be improved.

[0075] Furthermore, the disclosed embodiments further include the following additional aspects. (Appendix 1) An edge ring surrounding an outer periphery of an object to be etched supported on a substrate support in a plasma processing chamber, the edge ring has an inclined surface that becomes lower from an outer periphery toward an inner periphery, a thickness of the edge ring before plasma processing at a point Xa located on the inclined surface at an inner periphery portion relative to a middle line equidistant from the innermost periphery and the outermost periphery of the edge ring is defined as T1; a thickness of the edge ring before plasma processing at a point Xb located on the outer circumferential inclined surface from the intermediate line is defined as T2; The thickness of the edge ring after the plasma treatment at the point Xa is T3, The thickness of the edge ring after the plasma treatment at the point Xb is T4. The relationship (T1-T3)<(T2-T4) is satisfied. (Supplementary Note 2) The edge ring according to (Supplementary Note 1), wherein the angle of the inclined surface with respect to the horizontal plane is 3° to 7°.

[0076] The edge ring and etching apparatus according to the presently disclosed embodiments should be considered in all respects as illustrative and not restrictive. The embodiments can be modified and improved in various ways without departing from the scope and spirit of the appended claims. The matters described in the above embodiments can be configured in other ways without contradiction, and can be combined without contradiction. [Explanation of symbols]

[0077] 10 Etching equipment 12 Plasma Processing Chamber 14 Ring Assembly 14a Covering 16 Foundation 18 Electrostatic Chuck 60a1 sloped surface FR Edge Ring ST board support part

Claims

1. 1. An edge ring surrounding an outer periphery of an object to be etched supported on a substrate support in a plasma processing chamber, comprising: the edge ring has an inclined surface that becomes lower from an outer periphery toward an inner periphery, a thickness of the edge ring before plasma processing at a point Xa located on the inclined surface at an inner periphery portion relative to a middle line equidistant from the innermost periphery and the outermost periphery of the edge ring is defined as T1; a thickness of the edge ring before plasma processing at a point Xb located on the inclined surface at an outer periphery portion from the intermediate line is defined as T2; The thickness of the edge ring after the plasma treatment at the point Xa is T3, When the thickness of the edge ring after the plasma treatment at the point Xb is T4, The relationship T2 / T1>T4 / T3 is satisfied. Edge ring.

2. 1. An edge ring surrounding an outer periphery of an object to be etched supported on a substrate support in a plasma processing chamber, comprising: the edge ring has an inclined surface that becomes lower from an outer periphery toward an inner periphery, a thickness of the edge ring before plasma processing at a point Xa located on the inclined surface at an inner periphery portion relative to a middle line equidistant from the innermost periphery and the outermost periphery of the edge ring is defined as T1; a thickness of the edge ring before plasma processing at a point Xb located on the inclined surface at an outer periphery portion from the intermediate line is defined as T2; The thickness of the edge ring after the plasma treatment at the point Xa is T3, When the thickness of the edge ring after the plasma treatment at the point Xb is T4, The relationship (T1-T3) < (T2-T4) is satisfied. Edge ring.

3. The edge ring before the plasma treatment is an unused edge ring in an etching apparatus, The edge ring after the plasma processing is an edge ring that has been used in the etching apparatus. The edge ring according to claim 1 or 2.

4. a step portion on an upper surface of the edge ring, the step portion being located inside the midline and having an outer side lower than an inner side; The inclined surface is provided on a part or the whole of the outer side of the step portion. The edge ring according to claim 1 .

5. The edge ring is formed of Si or SiC. The edge ring according to claim 1 .

6. The object to be etched is held on the substrate support; an end of the object to be etched is configured to extend outward beyond an inner peripheral side surface of the edge ring; The inclined surface is located outside an edge of the object to be etched. The edge ring according to claim 1 .

7. The angle of the inclined surface with respect to the horizontal plane is greater than or equal to 3° and less than or equal to 7°. The edge ring according to claim 1 .

8. a plasma processing chamber; a substrate support disposed within the plasma processing chamber; an edge ring surrounding an outer periphery of an object to be etched supported by the substrate support, the edge ring has an inclined surface that becomes lower from an outer periphery toward an inner periphery, a thickness of the edge ring before plasma processing at a point Xa located on the inclined surface at an inner periphery portion relative to a middle line equidistant from the innermost periphery and the outermost periphery of the edge ring is defined as T1; a thickness of the edge ring before plasma processing at a point Xb located on the outer circumferential inclined surface from the intermediate line is defined as T2; The thickness of the edge ring after the plasma treatment at the point Xa is T3, When the thickness of the edge ring after the plasma treatment at the point Xb is T4, An etching apparatus configured to satisfy the relationship T2 / T1>T4 / T3.

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