Substrate processing method and substrate processing apparatus

Abstract

A substrate processing method is a substrate processing method in a substrate processing apparatus, including the following steps: step a), supplying a process gas to a processing container in which a stage for placing a processed object having an etching film is provided, the process gas containing a gas containing a halogen other than fluorine and a gas containing oxygen; step b), performing plasma processing on the processed object using a first plasma of the process gas generated under first plasma generation conditions; step c), performing plasma processing on the processed object using a second plasma of the process gas generated under second plasma generation conditions, the second plasma generation conditions being plasma generation conditions in which a condition of high-frequency power and a processing time are different from those in the first plasma generation conditions and other conditions are the same as those in the first plasma generation conditions; and step d), repeating steps b) and c).

Description

Technical Field

[0001] This disclosure relates to a substrate processing method and a substrate processing apparatus. Background Technology

[0002] In recent years, with the advancements in semiconductor miniaturization, there has been a demand for improved control over the shape of apertures in dry etching processes. For example, a scheme has been proposed that uses a mixed gas containing Cl2 and O2 gases in silicon etching to prevent the formation of microtrenches and improve the vertical processability of the shape, as well as the mask selectivity (hereinafter also referred to as "selectivity") (Patent Document 1). Additionally, a scheme has been proposed that reduces damage to the workpiece and uses ALE (Atomic Layer Etching) method, which offers excellent control over the etching amount (Patent Document 2).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2010-080846

[0006] Patent Document 2: Japanese Patent Application Publication No. 2013-235912 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] This disclosure provides a substrate processing method and apparatus that can perform etching faster than gas switching methods and can also achieve improvements in selectivity and rectangular shape.

[0009] Solution for solving the problem

[0010] One aspect of the substrate processing method disclosed herein is a substrate processing method in a substrate processing apparatus, the substrate processing method comprising the following steps: step a), supplying a process gas to a processing container provided with a stage, the stage being used to hold a workpiece having an etched film, the process gas comprising a gas containing a halogen other than fluorine and a gas containing oxygen; step b), performing plasma processing on the workpiece using a first plasma of the process gas generated under a first plasma generation condition; step c), performing plasma processing on the workpiece using a second plasma of the process gas generated under a second plasma generation condition, the second plasma generation condition being a plasma generation condition in which the high-frequency power condition and the processing time differ from the high-frequency power condition and the processing time in the first plasma generation condition, but other conditions are the same as the first plasma generation condition; and step d), repeating steps b) and c).

[0011] The effects of the invention

[0012] According to this disclosure, etching can be performed faster than gas switching methods and can achieve improvements in selectivity and rectangular shape. Attached Figure Description

[0013] Figure 1 This is a diagram illustrating an example of a plasma processing apparatus according to one embodiment of the present disclosure.

[0014] Figure 2 This is a diagram illustrating an example of the relationship between the high-frequency power application mode and etching in this embodiment.

[0015] Figure 3 This is a diagram illustrating an example of the relationship between the application mode of high-frequency power and etching in ALE.

[0016] Figure 4 This is a diagram illustrating an example of the relationship between high-frequency power and dissociation cross-sectional area.

[0017] Figure 5 This is a diagram schematically illustrating an example of the state of a wafer in stage 1.

[0018] Figure 6 This is a diagram schematically illustrating an example of the state of a wafer in stage 2.

[0019] Figure 7 This is a flowchart illustrating an example of the etching process in this embodiment.

[0020] Figure 8 This is an example diagram showing the shape of the bottom portion.

[0021] Figure 9 This is a diagram illustrating an example of experimental results relating high-frequency power to the indentation and shape of silicon. Detailed Implementation

[0022] The embodiments of the substrate processing method and substrate processing apparatus of this disclosure will now be described in detail with reference to the accompanying drawings. Furthermore, the technology of this disclosure is not limited by the following embodiments.

[0023] In etching silicon films using a mask, a vertical etching process with a rectangular bottom, high selectivity, and significant mask residue is desired. However, there is a trade-off between the rectangular bottom shape and selectivity. As mentioned above, adding O2 gas to Cl2 gas can improve selectivity, but the bottom shape tends to become conical. Furthermore, during the etching process, the process gas is switched while repeatedly performing the protective film deposition and etching steps, requiring time for gas replacement within the processing vessel. This increases processing time and reduces productivity. Therefore, an etching method that is faster than gas switching and can simultaneously improve selectivity and rectangular shape is desired.

[0024] [Structure of the plasma processing device 100]

[0025] Figure 1 This is a diagram illustrating an example of a plasma processing apparatus according to one embodiment of the present disclosure. The plasma processing apparatus 100 includes a main body 10 and a control unit 20. In this embodiment, the plasma processing apparatus 100 uses inductively coupled plasma (ICP) to etch a film formed on a semiconductor wafer (hereinafter also referred to as a wafer) W, which is an example of a workpiece. In this embodiment, the semiconductor wafer W has, for example, an etchable film and a mask on the etchable film.

[0026] The main body 10 has a generally cylindrical, airtight chamber 101, for example, formed of anodized aluminum with an inner wall surface. The chamber 101 is grounded. The chamber 101 is divided vertically by an upper top plate 102. The upper surface of the upper top plate 102 serves as an antenna chamber 103 for housing an antenna 113. The lower surface of the upper top plate 102 serves as a processing chamber 104 for generating plasma. In this embodiment, the upper top plate 102 is formed of quartz and constitutes the top wall of the processing chamber 104. Alternatively, the upper top plate 102 may also be made of ceramic such as Al2O3.

[0027] A gas supply pipe 124 is provided on the side wall 104a of the processing chamber 104. One end of the gas supply pipe 124 is connected to the space S inside the processing chamber 104, and the other end is connected to the gas supply mechanism 120. Gas supplied from the gas supply mechanism 120 is supplied to the space S through the gas supply pipe 124. The gas supply mechanism 120 includes gas supply sources 121a-121c, MFC (Mass Flow Controller) 122a-122c, and valves 123a-123c. The gas supply mechanism 120 is an example of a gas supply unit.

[0028] MFC 122a is connected to a gas supply source 121a that supplies oxygen-containing gas and is used to control the flow rate of the oxygen-containing gas supplied from the gas supply source 121a. In this embodiment, the gas supply source 121a supplies, for example, O2 gas. Valve 123a controls the supply and cessation of the oxygen-containing gas, after its flow rate is controlled by MFC 122a, to the gas supply pipe 124.

[0029] MFC 122b is connected to a gas supply source 121b that supplies halogen-containing gas and is used to control the flow rate of the halogen-containing gas supplied from the gas supply source 121b. In this embodiment, the gas supply source 121b supplies, for example, Cl2 gas, HCl gas, HBr gas, or HI gas, which contains halogens other than fluorine. Valve 123b controls the supply and cessation of the halogen-containing gas to the gas supply pipe 124 after the flow rate is controlled by MFC 122b.

[0030] MFC 122c is connected to a gas supply source 121c that supplies rare gas and is used to control the flow rate of rare gas supplied from the gas supply source 121c. In this embodiment, the gas supply source 121c supplies, for example, Ar gas. Valve 123c controls the supply and cessation of the rare gas supply to the gas supply pipe 124 after the flow rate is controlled by MFC 122c.

[0031] An antenna 113 is installed inside the antenna chamber 103. The antenna 113 has antenna leads 113a made of highly conductive metals such as copper and aluminum. The antenna leads 113a are formed into arbitrary shapes such as loops or spirals. The antenna 113 is isolated from the upper top plate 102 by a spacer 117 made of insulating components.

[0032] One end of a power supply component 116 extending upwards towards the antenna chamber 103 is connected to terminal 118 of antenna lead 113a. One end of a power supply line 119 is connected to the other end of the power supply component 116, and a high-frequency power supply 115 is connected to the other end of the power supply line 119 via a matching adapter 114. The high-frequency power supply 115 supplies high-frequency power at frequencies above 10 MHz (e.g., 27 MHz) to the antenna 113 via the matching adapter 114, power supply line 119, power supply component 116, and terminal 118. This creates an induced electric field in the space S within the processing chamber 104 below the antenna 113, which plasmaizes the gas supplied from the gas supply pipe 124, thereby generating inductively coupled plasma within the space S. The antenna 113 is an example of a plasma generation unit. Furthermore, in the following description, the high-frequency power supplied from the high-frequency power supply 115 may sometimes be referred to as a second high-frequency power, a source, or a source.

[0033] A circular plate-shaped base 126, made of a conductive material such as aluminum, is provided on the bottom wall of the processing chamber 104 for holding the wafer W, which is the object to be processed. The base 126 also functions as an electrode for attracting ions (for biasing) in the generated plasma. The base 126 is supported by a cylindrical base support 127 made of an insulator.

[0034] Additionally, a high-frequency power supply 128 for biasing is connected to the base 126 via a power supply rod 130 and a matching device 129. High-frequency power at a frequency of 10 MHz or higher (e.g., 13 MHz) is supplied from the high-frequency power supply 128 to the base 126. Furthermore, in the following description, the high-frequency power supplied from the high-frequency power supply 128 is sometimes referred to as first high-frequency power, bias, or bias. Additionally, the high-frequency power supply 128 sometimes functions as a plasma excitation source to generate plasma within space S. This plasma is capacitively coupled plasma (CCP).

[0035] An electrostatic holding disk 131 for holding the wafer W by electrostatic attraction is provided on the upper surface of the base 126. An edge ring 132 is provided on the outer periphery of the electrostatic holding disk 131 in a manner that surrounds the wafer W. The edge ring 132 is sometimes also referred to as a focusing ring.

[0036] Additionally, a flow path 133 for circulating refrigerant such as cooling water is formed inside the base 126. The flow path 133 is connected to a cooling unit (not shown) via a pipe 134, from which temperature-regulated refrigerant is supplied into the flow path 133 via the cooling unit through the pipe 134.

[0037] A gas supply pipe 135 is provided inside the base 126. This gas supply pipe 135 is used to supply a heat transfer gas, such as He gas, between the electrostatic holding pad 131 and the wafer W. The gas supply pipe 135 passes through the electrostatic holding pad 131, and the space inside the gas supply pipe 135 is in communication with the space between the electrostatic holding pad 131 and the wafer W. Furthermore, multiple lifting pins (not shown) for transferring the wafer W are provided on the base 126 in a manner that allows them to protrude and retract relative to the upper surface of the electrostatic holding pad 131.

[0038] A loading / unloading outlet 140 is provided on the side wall 104a of the processing chamber 104. This loading / unloading outlet 140 is used to load and unload wafers W into and out of the processing chamber 104. The loading / unloading outlet 140 can be opened and closed by a gate valve G. By controlling the gate valve G to the open state, wafers W can be loaded and unloaded via the loading / unloading outlet 140. Furthermore, an annular partition 141 with numerous through holes is provided between the outer side wall of the base support portion 127 and the side wall 104a of the processing chamber 104.

[0039] An exhaust port 142 is formed on the bottom wall of the processing chamber 104, and an exhaust mechanism 143 is provided at the exhaust port 142. The exhaust mechanism 143 includes an exhaust pipe 144 connected to the exhaust port 142, an APC (Auto Pressure Controller) valve 145 for controlling the pressure inside the processing chamber 104 by adjusting the opening of the exhaust pipe 144, and a vacuum pump 146 for venting the processing chamber 104 through the exhaust pipe 144. In the etching process using plasma to vent the processing chamber 104 by the vacuum pump 146, the opening of the APC valve 145 is adjusted to maintain a specified vacuum level inside the processing chamber 104.

[0040] The control unit 20 includes memory such as ROM (Read Only Memory) and RAM (Random Access Memory), and a processor such as a CPU (Central Processing Unit). The processor within the control unit 20 controls the various parts of the main body 10 by reading and executing programs stored in the memory within the control unit 20. The specific processing performed by the control unit 20 will be described later.

[0041] [High-frequency power application mode]

[0042] Here, use Figure 2 and Figure 3 This will illustrate the relationship between the application mode of high-frequency power and etching in this embodiment and ALE. Furthermore, Figure 3 The high-frequency power application mode in the ALE shown is a mode used for comparison with the high-frequency power application mode of this embodiment. Figure 2 This is a diagram illustrating an example of the relationship between the high-frequency power application mode and etching in this embodiment. Figure 2 The diagram shows application mode 200, schematic diagrams 201 corresponding to stages 1-3 of application mode 200, and an etching amount curve 202. Additionally, in Figure 2 In this process, a silicon film is used as the etched film 203 on wafer W, and a silicon nitride film is used as the mask 204. Furthermore, in... Figure 2 In this process, a mixture of Cl2, O2, and Ar was used at specified flow rates.

[0043] Application mode 200 is a mode that changes the output of the first high-frequency power (Bias) and the second high-frequency power (Source) in each of stages 1 to 3. Furthermore, in Figure 2 In this diagram, stages 1 through 3 are designated as Phases I through III. In stage 1, for example, a first plasma is generated by setting the bias to 30W and the source to 100W. In stage 2, for example, a second plasma is generated by setting the bias to 300W and the source to 300W. In stage 3, for example, plasma generation is stopped by setting both the bias and the source to 0W. By repeating stages 1 through 3 of the application mode 200 as a unit cycle, the etched film 203 (silicon film) can be etched to the desired depth. Furthermore, the unit cycle of the application mode 200 is on the order of μs to ms.

[0044] Stage 1 is a modification stage in which Cl ions and free radicals (active species) are adsorbed onto the surface of the etched film 203 using a first plasma. As shown in schematic diagram 201, in stage 1, a modified region 205 with adsorbed Cl ions and free radicals is formed on the surface of the etched film 203 at the opening of the mask 204. Stage 2 is a stage in which the modified region 205 formed on the surface of the etched film 203 is etched using a second plasma. As shown in schematic diagram 201, in stage 2, the modified region 205 is etched, and a reaction product (byproduct) 206 is generated. The reaction product 206 is, for example, SiOCl. Stage 3 is a stage in which plasma generation is stopped and the reaction product 206 generated in stage 2 is vented. As shown in schematic diagram 201, in stage 3, the reaction product 206 is separated from the etched film 203 and vented. In addition, a portion of the reaction product 206 is deposited and adheres as a deposit to the sidewalls of the recesses of the etched film 203 and the mask 204.

[0045] Curve 202 represents the etching amount in stages 1 through 3. In stage 1, a first high-frequency power (Bias) of 30W is applied, thus performing some etching using Cl ions and free radicals. In stage 2, the first high-frequency power (Bias) increases to 300W, thus attracting Cl and O ions, free radicals, etc., to the W side of the wafer, and etching of the modified region 205 progresses. At timing 207, the modified region 205 is completely etched, after which the etched film 203 is directly etched, thus the etching rate slope becomes slower. In stage 3, plasma generation is stopped, so etching does not progress. Thus, in this embodiment, the etching of the etched film 203 is performed by repeatedly applying mode 200.

[0046] Figure 3 This is a diagram illustrating an example of the relationship between the application mode of high-frequency electricity and etching in ALE. Figure 3 The diagram shows application mode 210, schematic diagrams 211 corresponding to "steps 1 and 2" of application mode 210, and an etching amount curve 212. Additionally, in Figure 3 In, with Figure 2 Similarly, a silicon film was used as the etched film 214 on wafer 213, and a silicon nitride film was used as the mask 215. Furthermore, in Figure 3 In this process, the process gas is switched between "Step 1" and "Step 2", using a mixture of Cl2 and O2 at specified flow rates, and Ar gas respectively.

[0047] Application mode 210 is a mode of ALE performed by supplying a second high-frequency power (Source) in "Step 1" and a first high-frequency power (Bias) in "Step 2". Furthermore, in Figure 3 In this embodiment, "Step 1, 2" are referred to as "Step 1, 2". In "Step 1", for example, the output of the Source is increased (high) and the Bias is set to 0W to generate plasma for modifying the etched film 214. In "Step 2", for example, the output of the Bias is decreased (low) and the Source is set to 0W to generate plasma for etching the modified region. By repeating "Step 1, 2" of the application mode 210 as a unit cycle, the etched film 214 (silicon film) can be etched to the desired depth. Furthermore, since the process gas is switched between "Step 1, 2", the unit cycle of the application mode 210 is on the order of tens of seconds to several minutes. That is, compared with this embodiment, the etching process time in ALE is longer.

[0048] Step 1 involves using plasma generated by the Source to adsorb Cl and O ions and free radicals onto the surface of the etched film 214 for modification. As shown in schematic diagram 211, in Step 1, etchant 216, including Cl and O ions and free radicals, is adsorbed onto the surface of the etched film 214 at the opening of the mask 215 and onto the sides of the mask 215. At this time, the surface of the etched film 214 is modified by the etchant 216. Step 2 involves using plasma generated by the Bias to etch the etchant 216 adsorbed on the surface of the etched film 214 with Ar ions.

[0049] Curve 212 represents the etching amount in "Steps 1 and 2". In "Step 1", only the etchant 216 is adsorbed, so no etching occurs. In "Step 2", Ar ions are attracted to the W side of the wafer and, together with the adsorbed etchant 216, the etching of the etched film 214 progresses. At timing 217, when the adsorbed etchant 216 disappears, etching no longer progresses. In this way, in ALE, the etching of the etched film 214 is performed by repeatedly applying mode 210.

[0050] [Reaction Mechanism]

[0051] Next, use Figures 4 to 6 To illustrate the reaction mechanism in stages 1 and 2 of application mode 200 in this embodiment. Figure 4 This is a diagram illustrating an example of the relationship between high-frequency power and dissociation cross-sectional area. Figure 4 Curve 220 illustrates the relationship between the power of the source and the dissociation cross-sectional area in Cl2 and O2 gases. As shown in curve 220, when the source is 100W, i.e., in stage 1 of mode 200, Cl2 gas dissociates into free radicals Cl*, but O2 gas does not dissociate. On the other hand, when the source is 300W, i.e., in stage 2 of mode 200, both Cl2 and O2 gases dissociate into free radicals Cl* and O*. In stage 2, when Cl2 gas dissociates but O2 gas does not, a selectivity ratio cannot be achieved between the silicon of the etched film 203 and the silicon nitride film of the mask 204. On the other hand, when most of the O2 gas dissociates, the recess in the etched film 203 becomes conical. Therefore, in stage 2, adjustments are made to ensure that the amount of free radical O* remains constant. In addition, in application mode 200, the amount of free radicals Cl* and O* in each stage is changed by altering the high-frequency power in stages 1 and 2, thereby switching between modification and etching.

[0052] Figure 5 This is a diagram schematically illustrating an example of the state of a wafer in stage 1. (See diagram for example.) Figure 5 As shown, in stage 1, free radicals Cl* are attracted to the surface of the etched film 203 at the opening of the mask 204 on the wafer W by bias. At this time, on the bottom surface 221 of the recess formed in the etched film 203, Cl combines with Si, and the surface becomes halogen (Cl)-terminated, forming a SiCl mixed layer (modified layer). That is, it becomes self-limiting to suppress the adhesion of substances other than halogen (Cl).

[0053] Figure 6 This diagram schematically illustrates an example of the wafer's state in stage 2. Simultaneous processes are considered in stage 2. Figure 6 a) Figure 6 The reaction shown in c) is as follows. Figure 6 As shown in a), in stage 2, free radicals Cl* and O* are attracted to the surface of wafer W by bias. However, since the surface of bottom surface 221 is capped with Cl, the adhesion of O to bottom surface 221 can be suppressed, thereby suppressing the oxidation of the surface of bottom surface 221. Additionally, as... Figure 6 As shown in b), in stage 2, the surface of the bottom surface 221 is etched by attracting ions and free radicals, which act as etchants, to the surface of the wafer W via bias, and SiCl is generated as a reaction product. Additionally, as... Figure 6 As shown in c), in stage 2, the generated SiCl reacts with O* to become SiOCl, and is deposited as deposit 222 on the sidewalls of the recesses of the mask 204 and the etched film 203. Deposit 222 helps to improve selectivity and reduce curvature by protecting the sidewalls of the recesses, and because it is difficult for deposit 222 to adhere near the bottom surface 221 of the recesses, it also helps to make the bottom surface 221 of the recesses more rectangular.

[0054] [Etching Method]

[0055] Next, the etching method involved in this embodiment will be described. Figure 7 This is a flowchart illustrating an example of the etching process in this embodiment.

[0056] In the etching method of this embodiment, the control unit 20 opens the gate valve G of the loading / unloading outlet 140, and loads the wafer W, on which the mask 204 is formed on the etched film 203, into the processing chamber 104 and onto the electrostatic holding tray 131 on the base 126. The wafer W is held in the electrostatic holding tray 131 by applying a DC voltage. Thereafter, the control unit 20 closes the gate valve G and controls the exhaust mechanism 143 to exhaust gas from the space S, thereby achieving a predetermined vacuum level in the space S. Furthermore, the control unit 20 adjusts the temperature by controlling a temperature adjustment module (not shown) to achieve a predetermined temperature for the wafer W (step S1).

[0057] Next, the control unit 20 begins supplying process gas (step S2). As a process gas comprising a halogen gas (excluding fluorine), an oxygen-containing gas, and a rare gas, the control unit 20 supplies a mixture of Cl2, O2, and Ar to the processing chamber 104 via the gas supply pipe 124. The supplied mixture fills the space S within the processing chamber 104. Furthermore, the halogen gas (excluding fluorine) can also be a compound such as HCl, HBr, or HI. In this embodiment, the process gas conditions are kept constant until the etching process is complete.

[0058] The control unit 20 supplies first high-frequency power (bias voltage) for biasing the base 126 and second high-frequency power (source) for plasma excitation to the antenna 113 by controlling the high-frequency power supply 128 and high-frequency power supply 115. A mixed-gas plasma is generated by an induced electric field formed in space S. That is, in space S, the surface of the etched film 203 is modified by supplying halogen (Cl) free radicals generated using the first plasma generated under the first plasma generation conditions to the surface of the etched film 203. In other words, the control unit 20 performs plasma treatment on the wafer W using the first plasma of the process gas generated under the first plasma generation conditions (step S3). The wafer W is exposed to the first plasma, and primarily the bottom surface 221 of the recessed portion of the etched film 203 is modified.

[0059] The control unit 20 supplies a first high-frequency power (bias voltage) for biasing the base 126 and a second high-frequency power (source) for plasma excitation to the antenna 113 by controlling the high-frequency power supply 128 and the high-frequency power supply 115. A mixed-gas plasma is generated by an induced electric field formed in space S. That is, in space S, the etched film 203 is etched using an etchant generated under second plasma generation conditions. These second plasma generation conditions are plasma generation conditions where the high-frequency power conditions and processing time differ from those in the first plasma generation conditions, but other conditions are the same as those in the first plasma generation conditions. In other words, the control unit 20 performs plasma processing on the wafer W using the second plasma of the process gas generated under the second plasma generation conditions. These second plasma generation conditions are plasma generation conditions where the high-frequency power conditions and processing time differ from those in the first plasma generation conditions, but other conditions are the same as those in the first plasma generation conditions (step S4). The wafer W is exposed to a second plasma, and ions and free radicals acting as etchants are attracted to the wafer W side by a bias potential, thereby advancing the etching of the etchable film 203 not covered by the mask 204. Furthermore, the etching time using the second plasma in step S4 is set to a time sufficient to completely etch the modified region 205 after step S3 and to partially etch the etchable film 203.

[0060] The control unit 20 determines whether the desired shape has been obtained through steps S3 and S4 (step S5). If the control unit 20 determines that the desired shape has not been obtained (step S5: "No"), the process returns to step S3. On the other hand, if the control unit 20 determines that the desired shape has been obtained (step S5: "Yes"), the process ends. Furthermore, the control unit 20 may also include the following steps between steps S4 and S5, corresponding to stage 3 of the application mode 200: stopping the supply of the first high-frequency power and the second high-frequency power to stop plasma generation for a predetermined time.

[0061] When the process is finished, the control unit 20 stops supplying the process gas. Additionally, the control unit 20 applies opposite DC voltages to the electrostatic holding tray 131 to remove static electricity and peels the wafer W from the electrostatic holding tray 131. The control unit 20 opens the gate valve G. The wafer W is then removed from the space S of the processing chamber 104 via the inlet / outlet 140. In this way, in the plasma processing apparatus 100, etching can be performed faster than with gas switching methods, while also achieving improvements in selectivity and rectangular shape.

[0062] [Experimental Results]

[0063] Next, use Figure 8 and Figure 9 To illustrate the experimental results related to the rectangular shape of the bottom of the recess in the etched film 203. Figure 8 This is an example diagram showing the shape of the bottom portion. Figure 9 This is a diagram illustrating an example of experimental results relating high-frequency power to the recesses and shape portions of silicon. (See diagram for example.) Figure 8 As shown, a shaped portion 230 is formed between the bottom surface 221 of the etched film 203 and the sidewall of the recess. The lower the height 231 of the shaped portion 230, the closer the recess of the etched film 203 is to a rectangular shape.

[0064] Figure 9 The graph in Table 240 summarizes the effects on the etching amount (silicon recess) of the etched film 203 and the height 231 of the shape portion 230 when the first high-frequency power (Bias) and the second high-frequency power (Source) are varied in stage 1 of application mode 200. Furthermore, in Table 240, the upper half shows the case where the second high-frequency power (Source) is varied, and the lower half shows the case where the first high-frequency power (Bias) is varied. Additionally, in... Figure 9 In this context, the amount of etching of the recess of the etched film 203 (silicon recess) is denoted as "Si recess", and the height 231 of the shape portion 230 is denoted as "Shape".

[0065] First, when observing the upper part where the second high-frequency power (Source) is varied, even when the high-frequency power is changed from 100W to 600W, the slope of the approximate straight line of the etching amount of the recess (y = -0.0107x + 71.017) is -0.011, and the etching amount of the recess is about 60nm, which is almost unchanged. Therefore, it can be seen that even if the second high-frequency power (Source) of stage 1 is 100W, it can supply a sufficient amount of free radicals. On the other hand, the slope of the approximate straight line of the height 231 of the shape portion 230 (y = 0.0059x + 4.3881) is 0.006, but since the range of change of the height 231 is small, the effect is not significant. The smaller the high-frequency power, the smaller the height 231 becomes. That is to say, as indicated by box 241, it can be seen that the shape is closest to a rectangle when the second high-frequency power (Source) is 100W.

[0066] Next, when observing the lower half where the first high-frequency power (Bias) was changed, even when the high-frequency power changed from 30W to 300W, the slope of the approximate straight line of the etching amount of the recess (y = 0.0564x + 42.246) was still 0.056, and the etching amount of the recess was still about 40-60nm, with little change. Therefore, it can be seen that the first high-frequency power (Bias) in stage 1 has almost no effect on the etching amount of the recess. On the other hand, the slope of the approximate straight line of the height 231 of the shape portion 230 (y = 0.0088x + 8.0988) is 0.009, but because the range of change of the height 231 is small, the effect is large; the smaller the high-frequency power, the smaller the height 231 becomes. That is to say, as indicated by box 242, it can be seen that the shape is closest to a rectangle when the first high-frequency power (Bias) is 30W.

[0067] As shown in Table 240, the experimental results indicate that a second high-frequency power (Source) of 100W is sufficient for Stage 1. Even if the high-frequency power is increased to over 100W, the bottom of the concave portion will still become conical. Furthermore, it is known that the lower the first high-frequency power (Bias) of Stage 1, the closer the bottom of the concave portion is to a rectangular shape; therefore, 30W is suitable. Thus, in Figure 2 In stage 1 of the application mode 200 shown, the second high-frequency power (Source) is set to 100W and the first high-frequency power (Bias) is set to 30W.

[0068] [Variation Example]

[0069] In the above embodiment, the first plasma and the second plasma are inductively coupled plasma (ICP), but this is not a limitation. As a plasma generation method, the first plasma and the second plasma can also be capacitively coupled plasma (CCP). Furthermore, regarding the output of high-frequency power, the applied high-frequency power in the second plasma generation conditions can be higher than the applied high-frequency power in the first plasma generation conditions. Additionally, regarding the frequency of the high-frequency power, the frequency of the high-frequency power in the second plasma generation conditions can be higher than the frequency of the high-frequency power in the first plasma generation conditions. Furthermore, the conditions and processing time of the high-frequency power in the first and second plasma generation conditions can be adjusted according to the depth of the etched film 203 after etching.

[0070] Furthermore, in the above embodiment, the wafer W on which the mask 204 is formed on the etched film 203 is etched, but it is not limited to this. For example, the wafer on which silicon (Si) is formed surrounded by a silicon nitride film (SiN) may also be etched to etch silicon.

[0071] Furthermore, in the above embodiments, silicon films are listed as the etched film 203, but the method is not limited thereto. For example, the etched film 203 may also be a film containing at least silicon or germanium. In addition, the etched film 203 may also be a single-layer film of silicon, germanium, or any one of silicon and germanium, or a laminate of two or more of them.

[0072] Furthermore, in the above embodiments, silicon nitride film is listed as the mask 204, but it is not limited to this. For example, silicon oxide (SiO2) or silicon oxynitride (SiON) can also be used as the mask 204 as a silicon compound.

[0073] According to this embodiment, the control unit 20 executes step a), in which process gas is supplied to the processing container (chamber 101, processing chamber 104) on which a stage (base 126) is disposed. The stage (base 126) is used to hold the workpiece (wafer W) having the etched film. The process gas contains a halogen gas other than fluorine and an oxygen-containing gas. The control unit 20 executes step b), in which the workpiece is plasma-treated using a first plasma of the process gas generated under a first plasma generation condition. The control unit 20 executes step c), in which the workpiece is plasma-treated using a second plasma of the process gas generated under a second plasma generation condition. The second plasma generation condition is a plasma generation condition in which the high-frequency power condition and processing time are different from those of the first plasma generation condition, but other conditions are the same as those of the first plasma generation condition. The control unit 20 executes step d), in which steps b) and c) are repeated. As a result, etching can be performed faster than gas switching methods, while also achieving improvements in selectivity and rectangular shape.

[0074] Furthermore, according to this embodiment, in step b), halogen radicals generated using the first plasma are supplied to the surface of the film to be etched. Additionally, in step c), the film to be etched is etched using an etchant generated using the second plasma. As a result, etching can be performed faster than with gas switching methods, while also achieving improvements in selectivity and rectangular shape.

[0075] Furthermore, according to this embodiment, the second plasma generation condition is a condition that generates a bias potential on the workpiece. As a result, the film to be etched can be etched.

[0076] Furthermore, according to this embodiment, the amount of oxygen free radicals generated using the first plasma in step b) is less than the amount of oxygen free radicals generated using the second plasma in step c). As a result, it is possible to suppress the bottom surface from becoming conical at the recess of the etched film.

[0077] Furthermore, according to this embodiment, the control unit 20 executes step e), in which no plasma is generated. Additionally, in step d), steps b), c), and e) are repeated in the order of steps b), c), and e). As a result, the generated reaction products can be discharged.

[0078] Furthermore, according to this embodiment, the conditions for the process gas introduced in step e) are the same as those for the process gas introduced in steps b) and c). As a result, the decrease in productivity caused by the switching of process gases can be suppressed.

[0079] Furthermore, according to this embodiment, the film to be etched is a film containing at least silicon or germanium. As a result, these films can be etched in a way that balances improved selectivity and rectangular shape.

[0080] Furthermore, according to this embodiment, the film to be etched is a single layer of silicon, germanium, or a stacked film of two or more of these materials. As a result, these films can be etched while simultaneously achieving improvements in selectivity and rectangular shape.

[0081] Furthermore, according to this embodiment, the workpiece also has a mask made of silicon compound on the etched film. The etched film is then etched through an opening in the mask. As a result, the etched film can be etched in an improved manner, taking into account both the selectivity and the rectangular shape, corresponding to the opening of the mask.

[0082] Furthermore, according to this embodiment, the workpiece has a first region composed of an etched film and a second region composed of a silicon compound, and the first region is selectively etched relative to the second region. As a result, the first region can be etched in a way that balances improved selectivity and rectangular shape.

[0083] Furthermore, according to this embodiment, the silicon compound is at least one of silicon oxide, silicon nitride, and silicon oxynitride. As a result, the first region can be etched in a way that balances improved selectivity and rectangular shape.

[0084] Furthermore, according to this embodiment, the high-frequency power conditions and processing time in the first and second plasma generation conditions are adjusted based on the depth of the etched film. As a result, the extent of the protective film composed of reaction products (deposit) can be controlled.

[0085] Furthermore, according to this embodiment, the applied high-frequency power in the second plasma generation condition is higher than the applied high-frequency power in the first plasma generation condition. As a result, the modification (adsorption) step and the etching step can be repeated.

[0086] Furthermore, according to this embodiment, the frequency of the high-frequency electricity in the second plasma generation condition is higher than the frequency of the high-frequency electricity in the first plasma generation condition. As a result, the modification (adsorption) step and the etching step can be repeated.

[0087] Furthermore, according to this embodiment, the first plasma and the second plasma are inductively coupled plasmas or capacitively coupled plasmas. As a result, the modification (adsorption) step and the etching step can be repeated.

[0088] The embodiments described herein should be considered illustrative in all respects and not restrictive. The above embodiments may also be omitted, substituted, or modified in various ways without departing from the appended claims and their spirit.

[0089] Furthermore, in the above embodiments, inductively coupled plasma (ICP) was used as an example of a plasma source, but it is not limited to this. For example, any plasma source such as capacitively coupled plasma (CCP), microwave plasma, and magnetron plasma can also be used as a plasma source.

[0090] Furthermore, while silicon films are listed as the etched film in the above embodiments, the method is not limited to this. For example, it can also be applied to etching processes in which various silicon-containing films such as silicon oxide films and silicon nitride films are used as the etched film, and a silicon-containing film with a different selectivity ratio from the etched film is used as the mask.

[0091] Explanation of reference numerals in the attached figures

[0092] 10: Main body; 20: Control unit; 100: Plasma processing device; 101: Chamber; 103: Antenna chamber; 104: Processing chamber; 115, 128: High-frequency power supply; 120: Gas supply mechanism; 124: Gas supply pipe; 126: Base; 131: Electrostatic holding disk; S: Space; W: Wafer.

Claims

1. A substrate processing method, which is a substrate processing method in a substrate processing apparatus, the substrate processing method comprising the following steps: Step a) Supply process gas to a processing container equipped with a stage for placing a workpiece having an etched film, the process gas comprising a halogen gas other than fluorine and an oxygen-containing gas. Step b) involves using the first plasma of the process gas generated under the first plasma generation conditions to perform plasma treatment on the workpiece. Step c) The object to be processed is subjected to plasma treatment using the second plasma of the process gas generated under the second plasma generation conditions. The second plasma generation conditions are plasma generation conditions in which the high-frequency power conditions and processing time are different from the high-frequency power conditions and processing time in the first plasma generation conditions, but at least some other conditions are the same as the first plasma generation conditions. Process d) does not generate plasma; as well as Step e) is performed by repeating steps b), c), and d) in the order of steps b), c), and d).

2. The substrate processing method according to claim 1, wherein, In step b), free radicals of the halogen generated using the first plasma are supplied to the surface of the etched film. In step c), the etched film is etched using an etchant generated by the second plasma.

3. The substrate processing method according to claim 1 or 2, wherein, The second plasma generation condition is the condition that generates a bias potential on the object being treated.

4. The substrate processing method according to claim 1 or 2, wherein, In step b), the amount of oxygen free radicals generated using the first plasma is less than the amount of oxygen free radicals generated using the second plasma in step c).

5. The substrate processing method according to claim 1, wherein, The conditions under which the process gas is introduced in step d) are the same as those under which the process gas is introduced in steps b) and c).

6. The substrate processing method according to claim 1 or 2, wherein, The etched film is a film containing at least silicon or germanium.

7. The substrate processing method according to claim 6, wherein, The etched film is a single layer of silicon, germanium, or a stacked film of two or more of the two silicon and germanium.

8. The substrate processing method according to claim 1 or 2, wherein, The object being processed also has a mask made of silicon compound on the etched film. The etched film is etched through the opening of the mask.

9. The substrate processing method according to claim 1 or 2, wherein, The object to be processed has a first region consisting of an etched film and a second region consisting of a silicon compound, the first region being selectively etched relative to the second region.

10. The substrate processing method according to claim 8 or 9, wherein, The silicon compound is at least one of silicon oxide, silicon nitride, and silicon oxynitride.

11. The substrate processing method according to claim 1 or 2, wherein, The conditions of high-frequency power and the processing time in the first plasma generation conditions and the second plasma generation conditions are adjusted according to the depth of the etched film after etching.

12. The substrate processing method according to claim 1 or 2, wherein, The applied high-frequency power in the second plasma generation condition is higher than the applied high-frequency power in the first plasma generation condition.

13. The substrate processing method according to claim 1 or 2, wherein, The frequency of the high-frequency power in the second plasma generation condition is higher than the frequency of the high-frequency power in the first plasma generation condition.

14. The substrate processing method according to claim 1 or 2, wherein, The first plasma and the second plasma are inductively coupled plasmas or capacitively coupled plasmas.

15. A substrate processing apparatus comprising: Handling containers; A stage, disposed within the processing container, for holding a workpiece having an etched film; and Control Department in, The control unit is configured to perform the following controls: a) Control the substrate processing apparatus to supply process gas to the processing container, the process gas comprising a halogen gas other than fluorine and an oxygen-containing gas; b) Control the substrate processing apparatus to perform plasma treatment on the workpiece using the first plasma of the process gas generated under the first plasma generation conditions; c) Control the substrate processing apparatus to perform plasma processing on the workpiece using the second plasma of the process gas generated under the second plasma generation conditions, wherein the second plasma generation conditions are plasma generation conditions in which the high-frequency power conditions and processing time are different from the high-frequency power conditions and processing time in the first plasma generation conditions, and at least some other conditions are the same as the first plasma generation conditions. d) Control the substrate processing apparatus to prevent the generation of plasma; as well as e) Control the substrate processing apparatus to repeat b), c), and d) in the order of b), c), and d).

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