Substrate processing method and substrate processing apparatus

Abstract

To provide a substrate processing method capable of surely suppressing the formation of a residual in a fence shape and the generation of shoulder losing when a thickness is reduced by partially etching a substrate of which a circumference is etched.SOLUTION: A substrate processing method comprises: a first etching step of etching a circumference of a first region 210 and a second region 220 of a substrate 200 containing silicon; and a second etching step of etching the first region 210 so that a height of the first region 210 in a state where the circumference is etched by the first etching step becomes smaller than the height of the second region 220. The first etching step comprises: a first step of etching the circumference of the first region 210 so that a width of the first region 210 has a first width W1; and a second step of etching the circumference of the first region 210 so that the width of the first region 210 has a second width W2 that is smaller than the first width after the first step. In the first region 210, a level difference 230 is formed.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a substrate processing method and a substrate processing apparatus, and particularly to a substrate processing method and a substrate processing apparatus for etching a substrate.

Background Art

[0002] Conventionally, a substrate processing method for etching a substrate has been known (see, for example, Patent Document 1).

[0003] In the above Patent Document 1, in order to form an elongated torsion bar on a substrate containing silicon, the periphery of a portion corresponding to the torsion bar is etched, and then the portion corresponding to the torsion bar is etched to reduce the thickness of the torsion bar, thereby forming a torsion bar.

Prior Art Document

Patent Document

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, as in Patent Document 1 described above, there are cases where the torsion bar having an elongated shape is etched to reduce the thickness while the periphery of the torsion bar is etched. At this time, when the effect of protecting the substrate by the protective film is stronger than the effect of etching the substrate during etching, it is considered that the substrate near the protective film is difficult to be etched, and thus fence-shaped residues are formed at the ends near the protective film of the torsion bar. On the other hand, when the effect of etching the substrate during etching is stronger than the effect of protecting the substrate by the protective film, it is considered that the ends of the torsion bar are etched by etching and shoulder notches occur. Also, although it is possible to suppress the formation of fence-shaped residues and the occurrence of shoulder notches by adjusting the conditions of the etching process to balance the effect of protecting the substrate by the protective film and the effect of etching the substrate, it is necessary to accurately adjust the conditions of the etching process. For this reason, it is very difficult to adjust the etching conditions to balance the effect of protecting the substrate by the protective film and the effect of etching the substrate. As a result, there is a problem that it is difficult to surely suppress the formation of fence-shaped residues and the occurrence of shoulder notches when etching a part of the substrate whose periphery has been etched to reduce the thickness.

[0006] The present invention has been made to solve the above-described problems, and one object of the present invention is to provide a substrate processing method and a substrate processing apparatus capable of surely suppressing the formation of fence-shaped residues and the occurrence of shoulder notches when etching a part of a substrate whose periphery has been etched to reduce the thickness. Means for Solving the Problems

[0007] To achieve the above object, a substrate processing method according to a first aspect of the present invention includes a first etching step of etching the periphery of a first region and a second region of a substrate containing silicon, and a second etching step of etching the first region so that the height of the first region becomes smaller than the height of the second region among the first region and the second region whose peripheries are etched in the first etching step. The first etching step includes a first step of etching the periphery of the first region so that the width of the first region has a first width, and a second step of etching the periphery of the first region so that the width of the first region has a second width smaller than the first width after the first step. The first region On the side wall, such that the width at the upper part of the first region becomes larger forms a step.

[0008] In the substrate processing method according to the first aspect of the present invention, as described above, the first etching step includes a first step of etching the periphery of the first region so that the width of the first region has a first width, and a second step of etching the periphery of the first region so that the width of the first region has a second width smaller than the first width after the first step, and forms a step in the first region. Thereby, in the first etching step, the width of the upper part of the first region can be increased so that a step can be formed. As a result, in the second etching step, when the first region is etched, even if a fence-shaped residue is formed on the upper part of the first region, the fence-shaped residue cannot be supported in the first region when etched to the step portion where the width becomes smaller, so the fence-shaped residue is removed. Thereby, the formation of the fence-shaped residue can be surely suppressed. Further, even if a shoulder notch occurs in the upper part of the first region, the occurrence of the shoulder notch at the end can be suppressed by the amount of the width reduction when etched to the step portion where the width becomes smaller. As a result, when etching a part of the substrate whose periphery is etched to reduce the thickness, the formation of the fence-shaped residue and the occurrence of the shoulder notch can be surely suppressed. Further, in order to adjust the balance between the action of protecting the substrate with the protective film and the action of cutting the substrate by etching, it is not necessary to accurately adjust the conditions of the etching process in the second etching step, so it is possible to suppress the setting work of the etching process conditions from becoming complicated.

[0009] In the substrate processing method according to the first aspect, preferably, in the second etching step, the first region is etched such that the height of the first region is smaller than the height of the second region by a predetermined length, and in the first etching step, in the first step, the periphery of the first region is etched by a depth corresponding to the predetermined length. With such a configuration, a step where the width of the first region changes can be formed in the first etching step in accordance with the height position where the height of the first region is reduced in the second etching step.

[0010] In the substrate processing method according to the first aspect, preferably, in the first etching step, by dry etching using a Bosch process, in the first step, the periphery of the first region is etched such that the size of the concave portion of the uneven scallop shape becomes smaller, and in the second step, the periphery of the first region is etched such that the size of the concave portion of the scallop is larger than that in the first step, thereby forming a step in the first region. With such a configuration, by adjusting the size of the scallop in the first step and the second step, the width of the first region can be changed to easily form a step.

[0011] In this case, preferably, in the first etching step, in the second step, at least one of the etching time, pressure, gas flow rate, and coil applied power is increased compared to the first step, and the periphery of the first region is etched such that the size of the scallop is larger than that in the first step. With such a configuration, in the first etching step, by adjusting at least one of the etching time, pressure, gas flow rate, and coil applied power between the first step and the second step, the width of the first region can be changed to more easily form a step.

[0012] In the substrate processing method according to the first aspect, preferably, in a plan view, the first region and the second region are each processed into a comb shape, and the teeth of the comb are processed so as to be alternately arranged with each other. With this configuration, when processing the teeth of the comb to have different heights from each other, the formation of fence-shaped residues and the occurrence of shoulder chipping can be reliably suppressed, and the substrate can be accurately processed into a comb shape with different heights.

[0013] To achieve the above object, a substrate processing apparatus according to a second aspect of the present invention includes a processing chamber in which a substrate containing silicon is disposed, a gas supply unit that supplies a gas for processing the substrate to the processing chamber, a plasma generation unit that plasmatizes the gas in the processing chamber, and a control unit that controls the gas supply unit and the plasma generation unit to control an etching process on the substrate. The control unit controls an etching process that includes a first etching step of etching the peripheries of a first region and a second region of the substrate disposed in the processing chamber, and a second etching step of etching the first region so that the height of the first region is smaller than the height of the second region among the first region and the second region whose peripheries have been etched in the first etching step. The first etching step includes a first step of etching the periphery of the first region so that the width of the first region has a first width, and a second step of etching the periphery of the first region so that the width of the first region has a second width smaller than the first width after the first step. The first region On the side wall, such that the width at the upper part of the first region becomes larger forms a step.

[0014] In the substrate processing apparatus according to the second aspect of the present invention, as described above, the first etching step includes a first step of etching the periphery of the first region so that the width of the first region has a first width, and after the first step, a second step of etching the periphery of the first region so that the width of the first region has a second width smaller than the first width, and a step is formed in the first region. Thereby, in the first etching step, the width of the upper part of the first region can be increased so that a step can be formed. As a result, in the second etching step, when the first region is etched, even if a fence-shaped residue is formed on the upper part of the first region, when etching reaches the step portion where the width becomes smaller, the residue cannot be supported in the first region, so the fence-shaped residue is removed. Thereby, the formation of the fence-shaped residue can be surely suppressed. Further, even if a shoulder notch occurs in the upper part of the first region, when etching reaches the step portion where the width becomes smaller, the occurrence of the shoulder notch at the end can be suppressed by the amount of the width reduction. As a result, when etching a part of the substrate whose periphery has been etched to reduce the thickness, a substrate processing apparatus capable of surely suppressing the formation of a fence-shaped residue and the occurrence of a shoulder notch can be provided. Further, in order to adjust the balance between the action of protecting the substrate with the protective film and the action of etching the substrate, it is not necessary to accurately adjust the conditions of the etching process, so it is possible to provide a substrate processing apparatus that suppresses the setting work of the etching process conditions in the second etching process from becoming complicated.

Effects of the Invention

[0015] According to the present invention, as described above, when etching a part of the substrate whose periphery has been etched to reduce the thickness, the formation of a fence-shaped residue and the occurrence of a shoulder notch can be surely suppressed.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Embodiments for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0018] With reference to FIG. 1, a substrate processing apparatus 100 for performing the substrate processing method of this embodiment will be described.

[0019] (Substrate Processing Apparatus) As shown in FIG. 1, the substrate processing apparatus 100 is a plasma processing apparatus that forms plasma in the processing chamber 10 to perform dry etching of the substrate 200. The substrate 200 is a silicon wafer formed of silicon. The substrate processing apparatus 100 is processed, for example, as shown in FIG. 2, so as to have a comb-tooth electrode unit 201 (comb-tooth portion 201a, connecting portion 201b) and a comb-tooth electrode unit 202 (comb-tooth portion 202a, connecting portion 202b) in a comb-tooth shape. Specifically, the comb-tooth portion 201a is formed in the first region 210 of the substrate 200, and the comb-tooth portion 202a is formed in the second region 220 of the substrate 200. Further, the first region 210 and the second region 220 are each processed into a comb-tooth shape in a plan view, and the teeth of the comb teeth are processed so as to be alternately arranged with each other. Further, the comb-tooth portion 201a of the first region 210 is formed so as to have a smaller height than the comb-tooth portion 202a of the second region 220. Further, the comb-tooth portion 201a and the comb-tooth portion 202a are in a floating state in a direction perpendicular to the substrate 200. The substrate 200 on which the comb-tooth electrode units 201 and 202 are formed is used for, for example, MEMS devices such as acceleration sensors, gyro sensors (angular velocity sensors), and vibrating mirrors.

[0020] The substrate processing apparatus 100 includes a processing chamber 10, a substrate placement unit 20, a gas supply device 30, a plasma generation device 40, an exhaust device 50, a high-frequency power supply 60, and a control unit 70. The processing chamber 10 is an example of the "processing chamber" in the claims. The gas supply device 30 is an example of the "gas supply unit" in the claims. The plasma generation device 40 is an example of the "plasma generation unit" in the claims.

[0021] The processing chamber 10 has a closed space and houses the substrate placement unit 20 in the closed space. The processing chamber 10 is composed of an upper chamber 11 and a lower chamber 12 having an internally communicating space. The substrate 200 containing silicon is disposed in the processing chamber 10.

[0022] The substrate mounting portion 20 has a mounting surface 20a on which the substrate 200 is mounted. The substrate mounting portion 20 has a disk shape and includes a base 21, an electrostatic chuck 22 installed on the base 21, and a ring member 23 surrounding the periphery of the electrostatic chuck 22. The substrate mounting portion 20 is provided so as to be movable up and down within the processing chamber 10 by an elevating cylinder 25. The electrostatic chuck 22 is connected to an electrostatic adsorption power supply (not shown) for applying a voltage for electrostatic adsorption. When a voltage is applied to the electrostatic chuck 22, the substrate 200 is adsorbed to the mounting surface 20a which is the upper surface of the electrostatic chuck 22 by electrostatic induction. Note that an internal pipe (not shown) is provided in the substrate mounting portion 20, and a chiller device (not shown) for introducing a predetermined refrigerant into this internal pipe and circulating the refrigerant while controlling the temperature of the refrigerant (for example, controlling it to 10°C) is attached. Thereby, during the execution of plasma processing, the substrate mounting portion 20 is cooled. Also, during the execution of plasma processing, a cooling gas (inert gas such as He gas) is supplied from a predetermined cooling gas supply pipe (not shown) to the back surface of the substrate 200, and the substrate 200 is cooled.

[0023] The gas supply device 30 supplies a gas for processing the substrate 200 to the processing chamber 10. Specifically, the gas supply device 30 supplies an etching gas and a protective film forming gas into the processing chamber 10. The gas supply device 30 includes an SF6 gas supply unit 31 that supplies SF6 gas as the etching gas and a C4F8 gas supply unit 32 that supplies C4F8 gas as the protective film forming gas. Each gas supply unit is connected into the processing chamber 10 from the upper surface of the upper chamber 11 by a branched supply pipe 33 for gas supply. Through the supply pipe 33, SF6 gas and C4F8 gas are supplied into the processing chamber 10.

[0024] The plasma generation device 40 converts the gas in the processing chamber 10 into plasma. Specifically, the plasma generation device 40 is a device that generates inductively coupled plasma (ICP) using the gas supplied into the processing chamber 10. The plasma generation device 40 includes a spiral coil 41 provided on the outer periphery of the upper chamber 11, and a high-frequency power supply 42 that supplies high-frequency power to the coil 41. By supplying high-frequency power to the coil 41 by the high-frequency power supply 42, the gas supplied into the upper chamber 11 is converted into plasma.

[0025] The exhaust device 50 reduces the pressure in the processing chamber 10. The exhaust device 50 includes a vacuum pump 51 that exhausts the gas in the processing chamber 10, and an exhaust pipe 52 that connects the vacuum pump 51 to the inside of the processing chamber 10. Through the exhaust pipe 52, the vacuum pump 51 exhausts the gas in the processing chamber 10, bringing the inside of the processing chamber 10 to a predetermined pressure state close to vacuum.

[0026] The high-frequency power supply 60 supplies high-frequency power for the bias potential to the substrate mounting portion 20. The high-frequency power supply 60 supplies high-frequency power to the base 21 of the substrate mounting portion 20, thereby applying a bias potential between the substrate mounting portion 20 (base 21) and the plasma.

[0027] The control unit 70 controls each part of the substrate processing apparatus 100. Specifically, it controls the gas supply device 30 and the plasma generation device 40 to control the etching process on the substrate 200.

[0028] (Outline of the substrate processing method) Next, the outline of the substrate processing method of the present embodiment will be described. As shown in FIGS. 3(A) to 3(D), the substrate processing method of the present embodiment includes a first etching step of etching the peripheries of the first region 210 and the second region 220 of the substrate 200 containing silicon, and, among the first region 210 and the second region 220 whose peripheries have been etched in the first etching step, a second etching step of etching the first region 210 so that the height of the first region 210 is smaller than the height of the second region 220.

[0029] Note that the periphery of the first region 210 and the second region 220 (the portion to be etched in the first etching step) does not include, in the example shown in FIG. 2, the connecting portion 201b connected to the first region 210 (the comb tooth portion 201a) and the connecting portion 202b connected to the second region 220 (the comb tooth portion 202a). That is, the periphery of the first region 210 and the second region 220 (the portion to be etched in the first etching step) includes the adjacent portion (I) of the first region 210 (the comb tooth portion 201a) and the second region 220 (the comb tooth portion 202a) in the direction (Y direction) in which the first region 210 (the comb tooth portion 201a) and the second region 220 (the comb tooth portion 202a) face each other. Further, the periphery of the first region 210 and the second region 220 (the portion to be etched in the first etching step) includes the portion (II) adjacent to the front end surface of the first region 210 (the end portion on the side opposite to the connecting portion 201b in the X direction) and the portion (III) adjacent to the front end surface of the second region 220 (the end portion on the side opposite to the connecting portion 202b in the X direction). Also, the first region 210 and the second region 220 are three-dimensional regions. That is, the first region 210 and the second region 220 are regions that include dimensions in the depth direction (Z direction) in addition to the X direction and the Y direction (plane).

[0030] And in the substrate processing method of the present embodiment, as shown in FIGS. 3(B) and 3(C), the first etching step includes a first step of etching the periphery of the first region 210 so that the width of the first region 210 has a first width W1, and a second step of etching the periphery of the first region 210 so that the width of the first region 210 has a second width W2 smaller than the first width W1 after the first step, and a step 230 is formed on the side wall of the first region 210.

[0031] Specifically, as shown in FIG. 3(D), in the second etching step, the first region 210 is etched such that the height of the first region 210 is smaller than the height of the second region 220 by a predetermined length L1. Also, as shown in FIG. 3(B), in the first etching step, in the first process, the periphery of the first region 210 is etched such that the width of the first region 210 has a first width W1 by a depth L2 corresponding to the predetermined length L1. The length L1 etched in the second etching step (the amount by which the height of the first region 210 is shortened) is preferably, for example, a length of 1 times or more and 1.1 times or less with respect to the depth L2 etched in the first process of the first etching step. That is, the length L1 is about 1 times or more and 1.3 times or less of the depth L2. Preferably, the length L1 is about 1 times or more and 1.2 times or less of the depth L1. More preferably, the length L1 is about 1 times or more and 1.1 times or less of the depth L2. Also, for L1 and L2, the average value of the surface of the substrate 200 may be used, or the value of the portion of the substrate 200 where the amount of etching is large may be used, or the value of the portion of the substrate 200 where the amount of etching is small may be used.

[0032] Also, as shown in FIG. 4, in the first etching step, by dry etching using a Bosch process, in the first process, the periphery of the first region 210 is etched such that the size D1 of the concave portion of the scallop having an uneven shape becomes smaller. Also, in the second process, the periphery of the first region 210 is etched such that the size D2 of the concave portion of the scallop is larger than that in the first process, thereby forming a step 230 on the side wall of the first region 210. Note that the size of the scallop in the first region 210 in FIG. 4 is exaggeratedly drawn large for the purpose of explanation.

[0033] In dry etching by the Bosch process, the processes of forming a protective film, anisotropic etching, and isotropic etching are repeated a plurality of times. In the process of forming a protective film, C4F8 gas is supplied and plasma is generated by discharge to form a protective film on the substrate 200. In the anisotropic etching process, SF6 gas is supplied and plasma is generated by discharge. Then, the ions in the plasma are made to collide with the substrate 200 to remove the protective film on the bottom surface. In the isotropic etching process, SF6 gas is supplied and plasma is generated by discharge. Then, the radicals in the plasma react with the silicon of the substrate 200 to isotropically etch the silicon in the portion where the protective film has been removed. A scallop is formed for each cycle of performing the protective film formation process, anisotropic etching process, and isotropic etching process. Note that the number of cycles is set according to the depth to be etched.

[0034] In addition, in the first etching step, in the second step, at least one of the etching time, pressure, gas flow rate, and coil power (coil applied power) is made larger than in the first step so that the size of the scallop becomes larger than in the first step, and the periphery of the first region 210 is etched. For example, as shown in FIG. 5, in the second step, the time of etching (Etch2) is made longer than in the first step, and the pressure of etching (Etch2) is made larger than in the first step. Here, in the etching process, in etching (Etch1), the protective film on the bottom surface is mainly removed by anisotropic etching. Also, in etching (Etch2), in addition to downward etching, lateral etching progresses by isotropic etching. That is, by making the time of etching (Etch2) longer, the lateral etching progresses more, so that the size of the scallop becomes larger. Note that the gas flow rate in the etching (Etch2) of the second step may be made larger than the gas flow rate in the etching (Etch2) of the first step. Also, the coil power (Coil RF) in the etching (Etch2) of the second step may be made larger than the coil power in the etching (Etch2) of the first step.

[0035] In the second etching step, as shown in FIG. 6, when reducing the height of the first region 210 in a state where the step 230 is formed in the first etching step, even if a fence-shaped residue is formed on the upper part of the first region 210, when etching is performed up to the portion of the step 230 whose width becomes smaller, the fence-shaped residue cannot be supported in the first region 210. As a result, the fence-shaped residue is removed.

[0036] On the other hand, when reducing the height of a part of the substrate region, when there is no step 230, as in the comparative example shown in FIG. 7, when the etching in the Bosch process is performed, if the action of protecting the substrate by the protective film is stronger than the action of etching the substrate by the etching, since the substrate near the protective film is difficult to be etched, a fence-shaped residue is formed at the end near the protective film in the region where the height of the substrate is reduced. Specifically, for the substrate before the treatment shown in FIG. 8(A), in FIG. 8(B), a protective film is formed. Then, in FIG. 8(C), the protective film on the bottom surface is removed by anisotropic etching. Here, when the protective film is strong, the progress of etching of the substrate (Si) near the protective film becomes slow. That is, in FIG. 8(D), the progress of etching is slower at the end b closer to the protective film than at the central part a. Specifically, at the time of isotropic etching after the removal of the protective film (anisotropic etching), the central part a reacts with radicals over the entire surface, while at the end b near the protective film, since the protective film is attached, the etching of the substrate (Si) is difficult to proceed. Therefore, as shown in FIG. 8(E), a fence-shaped residue is formed at the end of the processed substrate close to the protective film.

[0037] Also, as in the comparative example shown in FIG. 9, when performing etching in the Bosch process, if the action of etching the substrate by the etching is stronger than the action of protecting the substrate by the protective film, the end of the region where the height of the substrate is reduced by the etching is cut, and shoulder chipping occurs.

[0038] (Substrate processing method (first example)) Next, the details of the substrate processing method of the present embodiment will be described. As shown in FIGS. 10 and 11, the substrate processing method according to the first example of the present embodiment includes the following steps S1 to S9.

[0039] In step S1 of FIG. 11, as shown in FIG. 10(A), a oxide film (SiO2) 204 is formed on the surface of the substrate 200 (on silicon (Si) 203). The formation of the oxide film 204 is performed, for example, by the CVD method. Note that the substrate 200 has a layer of silicon 203 formed on the support substrate 208 via the insulating layer 207. That is, the silicon 203 is a silicon-on-insulator (SOI). Note that the support substrate 208 may be attached after processing the silicon 203. Also, the material of the support substrate 208 is not particularly limited. For example, the support substrate 208 may be formed of silicon or may be formed of glass. Also, a cavity (hollow) may be formed in the support substrate 208 or the insulating layer 207. That is, the silicon 203 may be a Cavity-SOI. In step S2, as shown in FIG. 10(B), patterning of the resist 205 is performed at a position corresponding to the second region 220 of the substrate 200.

[0040] In step S3, as shown in FIG. 10(C), using the resist 205 as a mask, the oxide film 204 is etched to remove the oxide film 204 other than the resist 205 portion (the position corresponding to the second region 220). In step S4, as shown in FIG. 10(D), the resist 205 is peeled off to remove the resist 205 at the position corresponding to the second region 220.

[0041] In step S5, as shown in FIG. 10(E), patterning of the resist 206 is performed at positions corresponding to the first region 210 and the second region 220 of the substrate 200.

[0042] In steps S6 and S7, as the first etching step, as shown in FIG. 10(F), using the resist 206 as a mask, the silicon 203 is etched to etch the peripheries of the first region 210 and the second region 220.

[0043] Specifically, in step S6, as the first step of the first etching process, the scallop is controlled to become smaller, and the silicon 203 is etched by a predetermined depth L2. That is, the first step of the first etching process in step S6 etches the periphery of the first region 210 so that the width of the first region 210 has a first width W1 by a depth L2 corresponding to a predetermined length L1.

[0044] Then, in step S7, as the second step of the first etching process, the scallop is controlled to become larger, and the silicon 203 is etched.

[0045] In step S8, as shown in FIG. 10(G), the resist 206 is peeled off, and the resist 206 at the positions corresponding to the first region 210 and the second region 220 is removed.

[0046] In step S9, as the second etching process, as shown in FIG. 10(H), using the oxide film 204 as a mask, the silicon 203 is etched. Thereby, the height of the first region 210 is reduced.

[0047] That is, the second etching process in step S9 etches the first region 210 so that the height of the first region 210 is smaller than the height of the second region 220 by a predetermined length L1.

[0048] Thereafter, the insulating layer 207 (the layer below the silicon 203) serving as the sacrificial layer is removed. The insulating layer 207 is, for example, an oxide film, a nitride film, or the like. Thereby, the first region 210 and the second region 220 are formed in a comb shape. Also, the oxide film 204 remaining as the etching mask is removed. Note that the oxide film 204 may be removed simultaneously with the insulating layer 207 (sacrificial layer).

[0049] (Substrate processing method (second example)) As shown in FIGS. 12 and 13, the substrate processing method according to the second example of the present embodiment includes the following steps S11 to S19.

[0050] In step S11 of FIG. 13, as shown in FIG. 12(A), a oxide film (SiO2) 204 is formed on the surface of the substrate 200 (on silicon (Si) 203). The formation of the oxide film 204 is performed, for example, by CVD method. Note that a layer of silicon 203 is formed on the support substrate 208 via the insulating layer 207. That is, silicon 203 is a silicon-on-insulator (SOI). Note that the support substrate 208 may be attached after processing silicon 203. Also, the material of the support substrate 208 is not particularly limited. For example, the support substrate 208 may be formed of silicon or may be formed of glass. Further, a cavity (hollow) may be formed in the support substrate 208 or the insulating layer 207. That is, silicon 203 may be Cavity-SOI. In step S12, as shown in FIG. 12(B), patterning of the resist 205 is performed at a position corresponding to the second region 220 of the substrate 200.

[0051] In step S13, as shown in FIG. 12(C), using the resist 205 as a mask, the oxide film 204 is etched to reduce the height of the oxide film 204 except for the resist 205 portion (the position corresponding to the second region 220). In step S14, as shown in FIG. 12(D), patterning of the resist 206 is performed at positions corresponding to the first region 210 and the second region 220 of the substrate 200.

[0052] In step S15, as shown in FIG. 12(E), using the resist 206 as a mask, the oxide film 204 is etched to remove the oxide film 204 except for the resist 206 portion (the positions corresponding to the first region 210 and the second region 220).

[0053] In steps S16 and S17, as a first etching step, as shown in FIG. 12(F), using the oxide film 204 as a mask, the silicon 203 is etched to etch the peripheries of the first region 210 and the second region 220. Note that the resist 206 may be peeled off and removed prior to etching the silicon 203, or the resist 206 may be left without being removed and used as a mask together with the oxide film 204.

[0054] Specifically, in step S16, as the first step of the first etching process, the scallop is controlled to be reduced, and the silicon 203 is etched by a predetermined depth L2.

[0055] Then, in step S17, as the second step of the first etching process, the scallop is controlled to be increased, and the silicon 203 is etched.

[0056] In step S18, as shown in FIG. 12(G), the oxide film 204 is etched to remove the oxide film 204 from the first region 210.

[0057] In step S19, as the second etching process, as shown in FIG. 12(H), the silicon 203 is etched using the oxide film 204 as a mask. Thereby, the height of the first region 210 is reduced.

[0058] That is, in the second etching process of step S19, the first region 210 is etched so that the height of the first region 210 is smaller than the height of the second region 220 by a predetermined length L1.

[0059] Thereafter, the insulating layer 207 (the layer below the silicon 203) serving as a sacrificial layer is removed. The insulating layer 207 is, for example, an oxide film or a nitride film. As a result, the first region 210 and the second region 220 are formed in a comb shape. Also, the oxide film 204 remaining as an etching mask is removed. Note that the oxide film 204 may be removed simultaneously with the insulating layer 207 (sacrificial layer).

[0060] (Effect of this Embodiment) In this embodiment, the following effects can be obtained.

[0061] In the substrate processing method of this embodiment, as described above, the first etching step includes a first step of etching the periphery of the first region 210 so that the width of the first region 210 has a first width W1, and after the first step, a second step of etching the periphery of the first region 210 so that the width of the first region 210 has a second width W2 smaller than the first width W1, and a step 230 is formed in the first region 210. Thereby, in the first etching step, the upper width of the first region 210 can be increased so that the step 230 can be formed. As a result, in the second etching step, when the first region 210 is etched, even if a fence-shaped residue is formed on the upper part of the first region 210, when it is etched to the portion of the step 230 where the width becomes smaller, the fence-shaped residue cannot be supported in the first region 210, so the fence-shaped residue is removed. Thereby, the formation of the fence-shaped residue can be surely suppressed. Further, even if a shoulder notch occurs in the upper part of the first region 210, when it is etched to the portion of the step 230 where the width becomes smaller, the occurrence of the shoulder notch at the end can be suppressed by the amount of the width reduction. As a result, when a part of the substrate 200 whose periphery is etched is etched to reduce the thickness, the formation of the fence-shaped residue and the occurrence of the shoulder notch can be surely suppressed. Also, in order to adjust the balance between the action of protecting the substrate 200 with the protective film and the action of etching the substrate 200, it is not necessary to accurately adjust the conditions of the etching process, so it is possible to suppress the complication of the setting work of the conditions of the etching process.

[0062] Also, in this embodiment, as described above, the second etching step etches the first region 210 so that the height of the first region 210 is smaller than the height of the second region 220 by a predetermined length L1, and the first etching step etches the periphery of the first region 210 by a depth L2 corresponding to the predetermined length L1 in the first step. Thereby, in the first etching step, a step 230 in which the width of the first region 210 changes can be formed in accordance with the height position at which the height of the first region 210 is reduced in the second etching step.

[0063] Also, in the present embodiment, as described above, in the first etching process, by dry etching using a Bosch process, in the first step, the periphery of the first region 210 is etched so that the size D1 of the concave portion of the scallop having an uneven shape becomes smaller. In the second step, the periphery of the first region 210 is etched so that the size D2 of the concave portion of the scallop becomes larger than that in the first step, thereby forming a step 230 in the first region 210. Thus, by adjusting the size of the scallop in the first step and the second step, the width of the first region 210 can be changed to easily form the step 230.

[0064] Also, in the present embodiment, as described above, in the first etching process, in the second step, at least one of the etching time, pressure, gas flow rate, and coil applied power is increased compared to the first step, and the periphery of the first region 210 is etched so that the size of the scallop becomes larger than that in the first step. Thus, in the first etching process, by adjusting at least one of the etching time, pressure, gas flow rate, and coil applied power between the first step and the second step, the width of the first region 210 can be changed to more easily form the step 230.

[0065] Also, in the present embodiment, as described above, the first region 210 and the second region 220 are each processed into a comb shape in a plan view, and the teeth of the comb are processed so as to be alternately arranged with each other. Thus, when processing the teeth of the comb to have different heights from each other, the formation of fence-shaped residues and the occurrence of shoulder chipping can be reliably suppressed, and the substrate 200 can be accurately processed into a comb shape with different heights.

[0066] (Modification example) It should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the description of the above embodiments, and further includes all modifications (modification examples) within the meaning and scope equivalent to the scope of claims.

[0067] For example, in the above embodiment, an example of implementing the substrate processing method using the substrate processing apparatus 100 shown in FIG. 1 was shown, but the present invention is not limited thereto. The apparatus configuration of the substrate processing apparatus for implementing the substrate processing method of the present invention is not particularly limited and may be different from the apparatus configuration of FIG. 1.

[0068] Further, in the above embodiment, an example of a configuration in which, in the first etching step, in the second step of the first etching step, the time and pressure during isotropic etching are made larger than those in the first step was shown, but the present invention is not limited thereto. In the present invention, in the second step of the first etching step, other conditions may be set to be different from those in the first step.

[0069] Also, in the above embodiment, an example in which the substrate 200 to be processed is a Si substrate containing Si was shown, but the present invention is not limited thereto. In the present invention, the substrate 200 to be processed may be a SiGe substrate containing SiGe, or may be a SiC substrate containing SiC.

[0070] [Aspect] Those skilled in the art will understand that the above-exemplified embodiments are specific examples of the following aspects.

[0071] (Item 1) A first etching step of etching the peripheries of the first region and the second region of a substrate containing silicon, and A second etching step of etching the first region so that the height of the first region is smaller than the height of the second region among the first region and the second region in a state where the peripheries are etched by the first etching step, the substrate processing method comprising: The first etching step includes a first step of etching the periphery of the first region so that the width of the first region has a first width, and a second step of etching the periphery of the first region so that the width of the first region has a second width smaller than the first width after the first step, and forming a step in the first region.

[0072] (Item 2) The second etching process etches the first region such that the height of the first region is smaller than the height of the second region by a predetermined length. The substrate processing method according to item 1, wherein the first etching process etches the periphery of the first region by a depth corresponding to the predetermined length in the first step.

[0073] (Item 3) The substrate processing method according to item 1 or 2, wherein the first etching process etches the periphery of the first region by dry etching using a Bosch process such that the size of the concave portion of the scallop having an uneven shape becomes smaller in the first step, and etches the periphery of the first region such that the size of the concave portion of the scallop becomes larger than that in the first step in the second step, thereby forming a step in the first region.

[0074] (Item 4) The substrate processing method according to item 3, wherein the first etching process increases at least one of the etching time, pressure, gas flow rate, and coil applied power in the second step compared to the first step, and etches the periphery of the first region such that the size of the scallop becomes larger than that in the first step.

[0075] (Item 5) The substrate processing method according to any one of items 1 to 4, wherein the first region and the second region are each processed into a comb shape in a plan view, and the teeth of the comb are processed so as to be alternately arranged with each other.

[0076] (Item 6) A processing chamber in which a substrate containing silicon is disposed; A gas supply unit that supplies a gas for processing the substrate to the processing chamber; A plasma generation unit that plasmatizes the gas in the processing chamber; A control unit that controls the gas supply unit and the plasma generation unit to control the etching process on the substrate. The control unit controls an etching process that includes a first etching step of etching the peripheries of a first region and a second region of a substrate disposed in the processing chamber, and a second etching step of etching the first region such that the height of the first region is smaller than the height of the second region, among the first region and the second region whose peripheries have been etched in the first etching step. The first etching step includes a first step of etching the periphery of the first region such that the width of the first region has a first width, and a second step of etching the periphery of the first region such that the width of the first region has a second width smaller than the first width after the first step, and forms a step in the first region, a substrate processing apparatus.

Explanation of Signs

[0077] 10: Processing chamber, 30: Gas supply device (gas supply unit), 40: Plasma generation device (plasma generation unit), 70: Control unit, 100: Substrate processing apparatus, 200: Substrate, 210: First region, 220: Second region, 230: Step

Claims

1. A first etching step of etching the peripheries of a first region and a second region of a substrate containing silicon, and a second etching step of etching the first region such that the height of the first region is smaller than the height of the second region among the first region and the second region whose peripheries have been etched in the first etching step. The substrate processing method includes forming a step on a sidewall of the first region such that the width of an upper portion of the first region becomes larger. The first etching step includes a first step of etching the periphery of the first region such that the width of the first region has a first width, and a second step of etching the periphery of the first region such that the width of the first region has a second width smaller than the first width after the first step.

2. In the second etching step, the first region is etched such that the height of the first region is smaller than the height of the second region by a predetermined length. In the first etching step, in the first step, the periphery of the first region is etched by a depth corresponding to the predetermined length. The substrate processing method according to claim 1.

3. In the first etching step, by dry etching using a Bosch process, in the first step, the periphery of the first region is etched such that the size of a recess of a scallop having an uneven shape becomes smaller, and in the second step, the periphery of the first region is etched such that the size of the recess of the scallop is larger than that in the first step, thereby forming a step in the first region. The substrate processing method according to claim 1.

4. In the first etching step, in the second step, at least one of the etching time, pressure, gas flow rate, and coil applied power is increased compared to the first step, and the periphery of the first region is etched such that the size of the scallop is larger than that in the first step. The substrate processing method according to claim 3.

5. In plan view, the first region and the second region are each processed into a comb shape, and the teeth of the comb are processed such that they are alternately arranged with each other. The substrate processing method according to claim 1.

6. A processing chamber in which a substrate containing silicon is disposed, a gas supply unit that supplies a gas for processing the substrate to the processing chamber, a plasma generation unit that plasmatizes the gas in the processing chamber, A control unit that controls the gas supply unit and the plasma generation unit to control the etching process on the substrate, The control unit controls an etching process that includes a first etching step of etching the peripheries of a first region and a second region of a substrate disposed in the processing chamber, and a second etching step of etching the first region such that the height of the first region becomes smaller than the height of the second region among the first region and the second region whose peripheries have been etched in the first etching step. The first etching step includes a first step of etching the periphery of the first region such that the width of the first region has a first width, and a second step of etching the periphery of the first region such that the width of the first region has a second width smaller than the first width after the first step, and a substrate processing apparatus that forms a step on a sidewall of the first region such that the width of an upper portion of the first region becomes larger.

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