Dry etching device

Abstract

A dry etching apparatus capable of concentrically adjusting an etching rate is provided. The dry etching apparatus includes a sample stage provided with a sample and capable of self-rotation, an etching source that irradiates an etching medium to the sample, and a shielding portion provided at a position separate from the sample stage to hinder a portion of the irradiated etching medium from reaching the sample.

Description

Technical Field

[0001] This invention relates to a dry etching apparatus. Background Technology

[0002] Dry etching apparatuses that cut samples by irradiating ion beams are known (see, for example, Patent Documents 1 and 2).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2013-101851

[0006] Patent Document 2: Japanese Patent Application Publication No. 9-33410 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] Dry etching apparatuses are used, for example, to uniformly etch the surface of thin films deposited on wafers. Here, thin films formed on wafers using film-forming apparatuses such as sputtering devices tend to have a concentric thickness distribution due to the nature of their film-forming method. Specifically, the thickness of thin films formed on wafers sometimes gradually decreases from the periphery towards the center, or vice versa. In such cases, it is sometimes necessary to eliminate the thickness distribution of the film and make the thickness uniform within the plane. Conversely, for films with uniform thickness within the plane, it is sometimes necessary to create a concentric thickness distribution. These requirements can be achieved by changing the etching rate concentrically to cut the sample. However, even if existing dry etching apparatuses can uniformly etch the surface of the workpiece, it is difficult to change the etching rate concentrically to etch the surface of the workpiece.

[0009] The present invention was made to solve this problem by providing a dry etching apparatus capable of adjusting the etching rate in a concentric circle.

[0010] Technical solutions for solving the problem

[0011] This disclosure provides a dry etching apparatus comprising: a sample stage on which a sample is disposed and capable of rotation; an etching source that irradiates the sample with an etching medium; and a shielding portion disposed at a position separate from the sample stage to prevent a portion of the irradiated etching medium from reaching the sample.

[0012] Invention Effects

[0013] This invention provides a dry etching apparatus capable of concentrically adjusting the etching rate. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of a dry etching apparatus.

[0015] Figure 2 This is a top view showing an example of the top-view shape of the obscured area.

[0016] Figure 3 This is a top view showing an example of the top-view shape of the obscured area.

[0017] Figure 4 This is a top view showing an example of an etching rate that increases from the periphery of the sample toward the center.

[0018] Figure 5 This is a top view illustrating an example of an etching rate that increases from the center of the sample toward the periphery.

[0019] Figure 6 This is a schematic diagram illustrating the process of homogenizing the thickness of a thin film that thickens from the periphery toward the center of the sample within the plane.

[0020] Figure 7 This is a schematic diagram illustrating the process of homogenizing the thickness of a thin film that thickens from the center of the sample toward the periphery within the plane.

[0021] Figure 8 This is a schematic diagram illustrating the process of producing a concentric circle thickness distribution that thickens from the center of the sample toward the periphery when a thin film of uniform thickness in the plane is generated.

[0022] Figure 9 This is a schematic diagram illustrating the process of producing a concentric circle thickness distribution that thickens from the periphery towards the center of a thin film with uniform thickness in the plane.

[0023] Figure 10 It represents a part of the sample. Figure 1 An enlarged view of part A in the image.

[0024] Figure 11 This is a schematic diagram of grinding the sample surface using chemical mechanical grinding.

[0025] Figure 12 This is a schematic diagram of cutting the surface of a sample using a dressing tool.

[0026] Figure 13 This is a schematic diagram of etching the sample surface using the dry etching apparatus of this embodiment.

[0027] Figure 14 This is a graph representing the etching rate [nm / sec].

[0028] Figure 15 It is a graph showing the thickness of the film [nm] before etching, after short-time etching, and after long-time etching. Detailed Implementation

[0029] Embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, components labeled with the same reference numerals have the same or identical structures. Furthermore, the invention as claimed is not limited to the following embodiments. Additionally, all structures described in the embodiments are not necessarily essential technical solutions for solving the problem.

[0030] like Figure 1 As shown, the dry etching apparatus 10 of this embodiment includes a sample stage 11, an etching source 12, and a shielding portion 13. The etching method in the dry etching apparatus 10 can be any of sputtering etching, reactive ion etching (RIE), and gas etching, but from the viewpoint of easily adjusting the etching rate, sputtering etching or reactive ion etching with high anisotropy is preferred. Furthermore, from the viewpoint of easily adjusting the irradiation angle of the etching medium 20 onto the sample 30, the etching method is particularly preferred as it involves ion beam etching (IBE) within sputtering etching. Ion beam etching includes ion milling.

[0031] The sample stage 11 is used to hold the sample 30 when using the dry etching apparatus 10. The sample stage 11 is capable of rotation. The rotation is, for example, performed by a motor, and the rotation speed can be adjusted arbitrarily. The sample stage 11 can also be a stage capable of changing the tilt of the sample 30, so as to adjust the irradiation angle of the etching medium 20 onto the sample 30.

[0032] Etching source 12 irradiates etching medium 20 onto sample 30. In the case of ion beam etching, etching source 12 is an ion gun, and etching medium 20 is an ion beam. The ions in the ion beam can be, for example, argon ions, helium ions, xenon ions, krypton ions, etc. There can be one or more etching sources 12. The position and / or orientation of etching source 12 can also be changed to adjust the irradiation angle of etching medium 20 onto sample 30.

[0033] When the shielding part 13 is not obstructed, the etching source 12 irradiates the entire surface of the sample 30 disposed on the sample stage 11 with the etching medium 20. That is, when the shielding part 13 is not obstructed, the irradiation range of the etching medium 20 may also include the entire surface of the sample 30 disposed on the sample stage 11.

[0034] The shielding portion 13 is positioned separately from the sample stage 11 to prevent a portion of the irradiated etching medium 20 from reaching the sample 30. The material of the shielding portion 13 is not particularly limited as long as it can obstruct the etching medium 20; for example, it can be made of metal, ceramic, resin, etc. In this embodiment, the shape of the shielding portion 13 is assumed to be an arc-shaped wall vertically mounted on the base 14, but it is not particularly limited. Furthermore, the shape of the shielding portion 13 is only required to partially obstruct the etching medium; various changes can be made to its height from the base 14 and its outline when viewed from above. The top view of the shielding portion 13 is the shape of the shielding portion 13 when viewed parallel to the rotation axis of the sample 30; for example, it can be as follows: Figure 2 As shown, it is an arc shape, or it can be like... Figure 3 As shown, it is an annular shape surrounding the sample 30. The shielding part 13 can be composed of a single structure or a combination of multiple structures.

[0035] like Figure 1 As shown, the etching source 12 irradiates the etching medium 20, for example, from a direction inclined relative to the rotation axis of the sample stage 11. In this case, the shielding portion 13 is positioned at an appropriate height in the transverse direction (perpendicular to the rotation axis) of the sample stage 11, thereby partially obstructing the etching medium 20. Alternatively, the etching source 12 may irradiate the etching medium 20 parallel to the rotation axis of the sample stage 11. In this case, the shielding portion 13 can partially obstruct the etching medium 20, for example, by partially covering the sample stage 11.

[0036] like Figure 1 As shown, the sample stage 11 and the shielding part 13, which are separate from each other, can also be simultaneously disposed on the base 14. In this case, the base 14 does not rotate when the sample stage 11 rotates. That is, the shielding part 13, which is disposed separately from the sample stage 11 on the base 14, does not follow the rotation of the sample stage 11 when the sample stage 11 rotates. Furthermore, the position and / or orientation of the base 14 can also be changed to adjust the irradiation angle of the etching medium 20 onto the sample 30.

[0037] As described above, the dry etching apparatus 10 of this embodiment includes a rotatable sample stage 11 and a shielding portion 13. The shielding portion 13 is positioned separately from the sample stage 11 to prevent a portion of the irradiated etching medium 20 from reaching the sample 30. Using this shielding portion 13, etched and unetched areas are formed on the surface of the sample 30. Furthermore, in this state, as the sample stage 11 rotates, the sample 30 rotates, thereby forming, for example, always etched and unetched areas, resulting in an etching rate distribution. This etching rate distribution, generated due to the rotation of the sample 30, is concentric. This concentric etching rate can be adjusted by using the shielding portion 13 to adjust the range of the area (obstruction area) on the sample 30 that obstructs the etching medium 20. The range of the obstruction area can be adjusted by adjusting the shape of the shielding portion 13, its position, the irradiation angle, etc. The irradiation angle can be adjusted by adjusting the relative position and angle between the etching source 12 and the sample stage 11. Thus, the dry etching apparatus 10 of this embodiment can adjust the etching rate to a concentric circle.

[0038] In addition, by changing the shape, position, and irradiation angle of the shielding part 13 in stages or gradually during etching, the distribution of the etching rate can also be changed in stages or gradually. Figure 4 This illustrates an example where the etching rate increases from the periphery toward the center of the sample 30. Figure 5 This illustrates an example where the etching rate increases from the center of sample 30 towards the periphery. Furthermore, in... Figure 4 and Figure 5 In this context, the depth of color indicates the magnitude of the etching rate.

[0039] By adjusting the etching rate to a concentric circle as described above, for example, the thickness of the concentrically distributed thin film 33 and the like can be made uniform in the plane. Figure 6 This is a schematic diagram of a dry etching apparatus 10 that adjusts the range of the obstruction area by increasing the etching rate from the periphery to the center, so that the thickness of the thin film 33, which thickens from the periphery to the center, is uniform in the plane. Figure 7 This is a schematic diagram illustrating the process of using a dry etching apparatus 10, which adjusts the range of the obstruction region by increasing the etching rate from the center towards the periphery, to homogenize the thickness of the thin film 33, which thickens from the center towards the periphery, within its plane. The dashed lines in the diagram represent the surface of the thin film 33 before etching. Figure 6 The examples shown and Figure 7 In the example shown, by appropriately adjusting the distance between the shielding part 13 and the sample 30, the height of the shielding part 13, and the irradiation angle, the range of the obstruction area is different for each case, resulting in different distributions of etching rates.

[0040] Furthermore, by adjusting the etching rate to a concentric circle, a concentric circle thickness distribution can also be generated for films such as 33 with uniform thickness in the plane. Figure 8 This is a schematic diagram of a dry etching apparatus 10 that adjusts the range of the obstruction area by increasing the etching rate from the periphery to the center, producing a concentric circle thickness distribution that increases from the center to the periphery for a thin film 33 with uniform thickness in the plane. Figure 9 This is a schematic diagram illustrating the use of a dry etching apparatus 10, which adjusts the range of the obstruction area by increasing the etching rate from the center towards the periphery, to produce a concentric circle thickness distribution that thickens from the periphery towards the center for a thin film 33 with uniform thickness in the plane. Figure 8 The examples shown and Figure 9 In the example shown, by appropriately adjusting the distance between the shielding part 13 and the sample 30, the height of the shielding part 13, and the irradiation angle, the range of the obstruction area is different for each case, resulting in different distributions of etching rates.

[0041] In this embodiment, the dry etching apparatus 10 can easily etch the thin film 33 when the thin film 33 formed on the lower structure 32 such as the electrode is the object to be etched, without significantly changing the thickness of the thin film 33 in the portion overlapping with the lower structure 32 and the thickness of the thin film 33 in the portion not overlapping with the lower structure 32.

[0042] Figure 10 yes Figure 1 The enlarged view of part A in the image shows a portion of sample 30. In a comparative example, the surface of the thin film 33 formed on the underlying structure 32 is polished by chemical mechanical polishing (CMP). Figure 11 As shown, the surface of the thin film 33 is smoothed. However, in this case, the thickness of the thin film 33 varies significantly between the overlapping and non-overlapping portions with the underlying structure 32. Furthermore, in Figures 11-13 In the image, the dashed line represents the surface of the thin film 33 before etching.

[0043] Additionally, as another comparative example, an example using a trimmer is presented. The trimmer described here is a device that cuts the material by irradiating gas clusters while scanning the sample 30. When using a trimmer to cut the surface of the thin film 33 formed on the lower structure 32, even if the thickness of the thin film 33 is to be homogenized considering the presence of the lower structure 32, the scanning will result in overlapping and non-overlapping areas of the gas cluster irradiation range, or sometimes adjacent irradiation ranges with different cutting amounts. Therefore, as... Figure 12 As shown, steps are formed.

[0044] In the case of etching the surface of the thin film 33 formed on the lower structure 32 using the dry etching apparatus 10 of this embodiment, based on the characteristics of dry etching, such as Figure 13 As shown, the thickness of the thin film 33 is less likely to differ between the overlapping and non-overlapping portions of the underlying structure 32. Because of this effect, the dry etching apparatus 10 of this embodiment is particularly useful, for example, when the thin film 33 is the object to be etched, and it is desired that the thickness of the thin film 33 be equal in the overlapping and non-overlapping portions of the underlying structure 32.

[0045] As described above, the range of the area (obstruction area) on the sample 30 that is blocked by the shielding part 13 from the etching medium 20 can be adjusted according to the position of the shielding part 13, the shape of the shielding part 13, the irradiation angle of the etching medium 20 onto the sample 30, etc.

[0046] The location of the shielding portion 13 is, for example, the distance from the sample 30 to the shielding portion 13. If other conditions are the same, the closer the shielding portion 13 is to the sample 30, the larger the range of the obstruction area tends to be, and the farther the shielding portion 13 is from the sample 30, the smaller the range of the obstruction area tends to be.

[0047] As mentioned above, the shape of the shielding part 13 includes its height, top view shape, etc. If other conditions are the same, the greater the height of the shielding part 13, the larger the obstructed area tends to be; conversely, the smaller the height of the shielding part 13, the smaller the obstructed area tends to be. Regarding the top view shape of the shielding part 13, for example, if the shielding part 13 is arc-shaped when viewed from above, if other conditions are the same, the larger the central angle of the arc, the larger the obstructed area tends to be; and the smaller the central angle of the arc, the smaller the obstructed area tends to be.

[0048] The irradiation angle of the etching medium 20 onto the sample 30, in other words, is the irradiation angle of the etching medium 20 relative to the in-plane direction of the sample 30. If other conditions are the same, a smaller irradiation angle tends to result in a larger obstructed area, and a larger irradiation angle tends to result in a smaller obstructed area. The irradiation angle of the etching medium 20 onto the sample 30 can be adjusted by changing the relative position and angle between the etching source 12 and the sample stage 11.

[0049] At least one of the following can be changed: the presence or absence of the shielding part 13, the position of the shielding part 13, the shape of the shielding part 13, and the irradiation angle of the etching medium 20 onto the sample 30. Furthermore, it is preferable that at least any one of the following can be changed: the presence or absence of the shielding part 13, the position of the shielding part 13, the shape of the shielding part 13, and the irradiation angle of the etching medium 20 onto the sample 30; preferably, all of these can be changed. In the dry etching apparatus 10 of this embodiment, because the shielding part 13 is separated from the sample stage 11, the presence or absence of the shielding part 13, its position, and its shape can be easily changed.

[0050] The ability to change the presence or absence of the shielding part 13 means removing the shielding part 13 from the dry etching apparatus 10 or moving the shielding part 13 to a position that does not affect the irradiation of the etching medium 20. Examples of positions that do not affect the irradiation of the etching medium 20 include, for example, the side opposite to the etching source 12 across the sample stage 11, or below the base 14. By changing the presence or absence of the shielding part 13, the dry etching apparatus 10 of this embodiment can also be used in common applications where the entire surface of the sample 30 needs to be etched uniformly.

[0051] In addition, the shielding part 13 can also be fixed as an integral part of the dry etching device 10. In this case, the manufacturing cost of the device may be kept low by simplifying the device structure.

[0052] The dry etching apparatus 10 may also include a control unit 15, which controls at least one of the etching source 12, the sample stage 11, and the shielding part 13, and adjusts the area where the shielding part 13 obstructs the etching medium 20. In this case, the control unit 15 can also change the irradiation angle of the etching medium 20 onto the sample 30 by controlling the etching source 12 and / or the sample stage 11. In addition, the control unit 15 can also change at least one of the following by controlling the shielding part 13: whether the shielding part 13 is provided or not, the position of the shielding part 13, and the shape of the shielding part 13.

[0053] The control unit 15 can move the shielding part 13 below the base 14 when the shielding part 13 is not needed, and move the shielding part 13 to a position that can block the etching medium 20 when the shielding part 13 is needed. Thus, the position of the shielding part 13 can be changed.

[0054] The control unit 15 can change the shape of the shielding portion 13, for example, by increasing or decreasing the size of the shielding portion 13 in the circumferential and / or height directions of the sample 30. Furthermore, for example, when the shielding portion 13 is formed by combining multiple plates bent into thin rectangular fan shapes into a corrugated shape, the control unit 15 can change the shape of the shielding portion 13 by folding the corrugated shielding portion 13 or by moving only a portion of the plates.

[0055] The control unit 15 can also change the range of the obstruction area and the distribution of the etching rate by changing the shape, position, and irradiation angle of the shielding part 13 in stages during etching.

[0056] The control unit 15 can also adjust the range of the obstruction area by controlling at least one of the etching source 12, the sample stage 11, and the shielding part 13 based on the etching target. The "etching target" is the target of etching the sample 30 to what extent each part is to be etched.

[0057] The control unit 15 sets an etching target, for example, based on the state of the sample 30 before etching and the state of the sample 30 after etching, which becomes the target.

[0058] The presence or absence of the shielding part 13, the position of the shielding part 13, the shape of the shielding part 13, and the change of the irradiation angle of the etching medium 20 onto the sample 30 can also be manually controlled by the user.

[0059] Example

[0060] The present invention will be described in more detail below through embodiments, but the present invention is not limited to the following embodiments.

[0061] A sample 30 is prepared on a 6-inch substrate 31 having a thin film 33 that thickens from the periphery towards the center. The thin film 33 is a metal oxide film that serves as a thermistor film. As a comparative example, the dry etching apparatus 10 uses an ion beam etching apparatus without the shielding portion 13; as an embodiment, the dry etching apparatus 10 uses an ion beam etching apparatus with the shielding portion 13. In the embodiment, the shielding portion 13 is positioned separately from the sample stage 11 to prevent a portion of the irradiated etching medium 20 from reaching the sample 30.

[0062] The etching rates [nm / sec] in the comparative examples and embodiments are as follows at the top, center, and bottom of the thin film 33: Figure 14 As shown in the graph. The difference in etching rate between the periphery (upper and lower ends) and the center of the thin film 33 in the comparative example and embodiment is shown in Table 1.

[0063] [Table 1]

[0064] Difference in etching rate Comparative example (unshielded area) Approximately 0.01nm Example (with shielding) Approximately 0.05nm

[0065] according to Figure 14 The results shown in the charts and Table 1 confirm that the shielding portion 13 can increase the difference in etching rates between the periphery and the center of the thin film 33.

[0066] Furthermore, in the embodiment using the shielding portion 13, the thickness [nm] of the thin film 33 in the three stages—before etching, after a short etching time of 165 seconds, and after a long etching time of 330 seconds—is as follows: from the top end to the bottom end of the thin film 33... Figure 15 As shown in the chart. Furthermore, the in-plane film thickness distribution [%] in the above three stages is shown in Table 2. The in-plane film thickness distribution [%] is calculated using the following formula.

[0067] D=(T1-T2) / (T1+T2)×100

[0068] D: Intrafacial membrane thickness distribution [%)

[0069] T1: The thickness of the point with the greatest thickness among the measured points [nm]

[0070] T2: The thickness of the point with the smallest thickness among the measured points [nm]

[0071] [Table 2]

[0072] Inner membrane thickness distribution Before etching 3.77％ After short etching 2.93％ After long-term etching 1.54％

[0073] according to Figure 15 The results shown in the charts and Table 2 confirm that by using the dry etching apparatus 10 of this embodiment, the thickness of the film 33, which thickens from the periphery toward the center, can be made to be nearly uniform in the plane.

[0074] Explanation of reference numerals in the attached figures

[0075] 10…dry etching apparatus, 11…sample stage, 12…etching source, 13…shielding part, 14…base, 15…control part, 20…etching medium, 30…sample, 31…substrate, 32…lower structure, 33…film.

Claims

1. A dry etching apparatus, comprising: A sample stage on which a sample is placed and which is capable of rotating. An etching source that irradiates the sample with an etching medium; and A shielding portion is provided at a position separate from the sample stage to prevent a portion of the irradiated etching medium from reaching the sample.

2. The dry etching apparatus according to claim 1, wherein, The presence or absence of the shielding portion, the position of the shielding portion, the shape of the shielding portion, and the irradiation angle of the etching medium onto the sample can be changed at least one of the following:

3. The dry etching apparatus according to claim 1, wherein, The device includes a control unit that controls at least one of the etching source, the sample stage, and the shielding part to adjust the range of the obstruction area where the shielding part obstructs the etching medium.

4. The dry etching apparatus according to claim 3, wherein, The control unit adjusts the extent of the obstruction area based on the etch target, i.e., the degree to which each part of the sample is etched.

5. The dry etching apparatus according to claim 4, wherein, The control unit sets the etching target based on the state of the sample before etching and the state of the sample after etching, which becomes the target.

6. The dry etching apparatus according to claim 1, wherein, The etching source irradiates the entire surface of the sample disposed on the sample stage with the etching medium without the shielding portion obstructing the etching medium.

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