SUBSTRATE PROCESSING METHOD AND SUBSTRATE PROCESSING APPARATUS

Abstract

To provide a substrate treatment method and a substrate treatment device with which it is possible to perform etching that is faster than a gas switching scheme as well as capable of improving a selection ratio and a rectangular shape.SOLUTION: Provided is a substrate treatment method in a substrate treatment device, the substrate treatment method comprising: a) a step for supplying a process gas containing a gas that contains halogen except fluorine and a gas that contains oxygen to a treatment container provided with a placement table on which an object to be treated having a film to be etched is placed; b) a step for plasma-treating the object to be treated, by a first plasma of the process gas generated under a first plasma generation condition; c) a step for plasma-processing the object to be treated, by a second plasma of the process gas generated under a second plasma generation condition which is the same as the first plasma generation condition, except that a condition for and treatment time of high-frequency electric power are different; and d) a step for repeating the steps b) and c).SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to a substrate processing method and a substrate processing apparatus. [Background technology]

[0002] In recent years, with the advancement of miniaturization of semiconductors, there is a demand for improved controllability of the shape of holes in dry etching processes. For example, in silicon etching, it has been proposed to prevent the generation of micro-trenches and improve the vertical processability of the shape and the mask selectivity (hereinafter, simply referred to as "selectivity") by using a mixed gas containing Cl2 gas and O2 gas (Patent Document 1). It has also been proposed to perform etching using the ALE (Atomic Layer Etching) method, which has excellent controllability of the etching amount while reducing damage to the processed object (Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-080846 A [Patent Document 2] JP 2013-235912 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a substrate processing method and substrate processing apparatus capable of performing etching faster than the gas switching method and capable of simultaneously improving the selectivity and the rectangular shape. [Means for solving the problem]

[0005] A substrate processing method according to one embodiment of the present disclosure is a substrate processing method in a substrate processing apparatus, comprising: a) supplying a process gas containing a gas containing a halogen other than fluorine and a gas containing oxygen to a processing vessel in which a mounting table for mounting a workpiece having a film to be etched is disposed; b) plasma processing the workpiece with a first plasma of the process gas generated under first plasma generation conditions; c) plasma processing the workpiece with a second plasma of the process gas generated under second plasma generation conditions that are different from the first plasma generation conditions in terms of high frequency power conditions and processing time, but have the other conditions identical; and d) repeating b) and c). Effect of the Invention

[0006] According to the present disclosure, etching can be performed that is faster than the gas switching method and that can simultaneously improve the selectivity and the rectangular shape. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating an example of a plasma processing apparatus according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a diagram showing an example of the relationship between the application pattern of high frequency power and etching in this embodiment. [Diagram 3] FIG. 3 is a diagram showing an example of the relationship between the application pattern of high frequency power and etching in the ALE. [Figure 4] FIG. 4 is a diagram showing an example of the relationship between the high-frequency power and the dissociation cross section. [Diagram 5] FIG. 5 is a diagram illustrating an example of a state of a wafer in phase 1. In FIG. [Figure 6] FIG. 6 is a diagram illustrating an example of a state of the wafer in phase 2. In FIG. [Figure 7] FIG. 7 is a flowchart showing an example of the etching process in this embodiment. [Figure 8] FIG. 8 is a diagram showing an example of a shape at the bottom. [Figure 9] FIG. 9 is a diagram showing an example of an experimental result regarding the relationship between the high frequency power and the recess and shape of silicon. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a substrate processing method and a substrate processing apparatus will be described in detail with reference to the accompanying drawings. Note that the disclosed technology is not limited to the following preferred embodiments.

[0009] In etching a silicon film through a mask, vertical etching with a high selectivity is required so that the bottom of the recess after etching is rectangular and the remaining film of the mask is large. However, there is a trade-off between the rectangular shape of the bottom and the selectivity, and as described above, although the selectivity is improved by adding O2 gas to Cl2 gas, the bottom is likely to become tapered. In addition, when the step of depositing a protective film and the etching step are repeated in the etching process, the process gas used is switched, so it takes time to replace the process gas in the processing vessel. This increases the process processing time and reduces the throughput. Therefore, it is expected to perform etching that is faster than the gas switching method and can simultaneously improve the selectivity and the rectangular shape.

[0010] [Configuration of Plasma Processing Apparatus 100] 1 is a diagram showing an example of a plasma processing apparatus according to an embodiment of the present disclosure. The plasma processing apparatus 100 has a main body 10 and a control unit 20. The plasma processing apparatus 100 according to this embodiment etches a film to be etched formed on a semiconductor wafer (hereinafter also referred to as a wafer) W, which is an example of an object to be processed, by using inductively coupled plasma (ICP). In this embodiment, the semiconductor wafer W has, for example, a film to be etched and a mask on the film to be etched formed thereon.

[0011] The main body 10 has an airtight chamber 101 having a substantially cylindrical shape, the inner wall surface of which is formed of, for example, aluminum that has been anodized. The chamber 101 is grounded. The chamber 101 is divided into upper and lower compartments by an upper top plate 102. The upper surface side of the upper top plate 102 constitutes an antenna chamber 103 in which an antenna 113 is housed. The lower surface side of the upper top plate 102 constitutes a processing chamber 104 in which plasma is generated. In this embodiment, the upper top plate 102 is formed of quartz and constitutes the ceiling wall of the processing chamber 104. The upper top plate 102 may be formed of ceramics such as Al2O3.

[0012] A gas supply pipe 124 is provided on the sidewall 104a of the processing chamber 104, one end of which is connected to the space S inside the processing chamber 104 and the other end of which is connected to the gas supply mechanism 120. Gas supplied from the gas supply mechanism 120 is supplied into the space S via the gas supply pipe 124. The gas supply mechanism 120 includes gas supply sources 121a to 121c, MFCs (Mass Flow Controllers) 122a to 122c, and valves 123a to 123c. The gas supply mechanism 120 is an example of a gas supply unit.

[0013] The MFC 122a is connected to a gas supply source 121a that supplies an oxygen-containing gas, and controls 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. The valve 123a controls the supply and stop of the oxygen-containing gas, the flow rate of which is controlled by the MFC 122a, to the gas supply pipe 124.

[0014] The MFC 122b is connected to a gas supply source 121b that supplies a halogen-containing gas, and controls 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 as a halogen-containing gas other than fluorine. The valve 123b controls the supply and stop of the halogen-containing gas, the flow rate of which is controlled by the MFC 122b, to the gas supply pipe 124.

[0015] The MFC 122c is connected to a gas supply source 121c that supplies a rare gas, and controls the flow rate of the rare gas supplied from the gas supply source 121c. In this embodiment, the gas supply source 121c supplies, for example, Ar gas. The valve 123c controls the supply and stop of the rare gas, the flow rate of which is controlled by the MFC 122c, to the gas supply pipe 124.

[0016] An antenna 113 is disposed within the antenna chamber 103. The antenna 113 has an antenna wire 113a formed of a highly conductive metal such as copper or aluminum. The antenna wire 113a is formed in any shape such as a ring or a spiral. The antenna 113 is separated from the upper top plate 102 by a spacer 117 formed of an insulating material.

[0017] One end of a power supply member 116 extending upward from the antenna chamber 103 is connected to a terminal 118 of the antenna line 113a. One end of a power supply line 119 is connected to the other end of the power supply member 116, and the other end of the power supply line 119 is connected to a high-frequency power source 115 via a matching device 114. The high-frequency power source 115 supplies high-frequency power with a frequency of 10 MHz or more (for example, 27 MHz) to the antenna 113 via the matching device 114, the power supply line 119, the power supply member 116, and the terminal 118. As a result, an induction electric field is formed in the space S in the processing chamber 104 below the antenna 113, and the gas supplied from the gas supply pipe 124 is turned into plasma by this induction electric field, and an inductively coupled plasma is generated in the space S. The antenna 113 is an example of a plasma generating unit. In the following description, the high-frequency power supplied from the high-frequency power source 115 may be referred to as a second high-frequency power, a source, or a Source.

[0018] A disk-shaped susceptor 126 made of a conductive material such as aluminum is provided on the bottom wall of the processing chamber 104, on which a wafer W to be processed is placed. The susceptor 126 also functions as an electrode for attracting ions in the generated plasma (bias electrode). The susceptor 126 is supported by a cylindrical susceptor support 127 made of an insulating material.

[0019] Further, a high frequency power supply 128 for bias is connected to the susceptor 126 via a power feed rod 130 and a matching box 129. High frequency power having a frequency of 10 MHz or more (for example, 13 MHz) is supplied to the susceptor 126 from the high frequency power supply 128. In the following description, the high frequency power supplied from the high frequency power supply 128 may be referred to as a first high frequency power, a bias, or a bias. The high frequency power supply 128 may also function as a plasma excitation source, and may generate plasma in the space S. The plasma generated at this time is a capacitively coupled plasma (CCP).

[0020] An electrostatic chuck 131 for holding the wafer W by electrostatic attraction is provided on the upper surface of the susceptor 126, and an edge ring 132 is provided on the outer periphery of the electrostatic chuck 131 so as to surround the periphery of the wafer W. The edge ring 132 is sometimes called a focus ring.

[0021] Furthermore, a flow path 133 for circulating a coolant such as cooling water is formed inside the susceptor 126. The flow path 133 is connected to a chiller unit (not shown) via a pipe 134, and a temperature-adjusted coolant is supplied from the chiller unit into the flow path 133 via the pipe 134.

[0022] A gas supply pipe 135 for supplying a heat transfer gas such as He gas between the electrostatic chuck 131 and the wafer W is provided inside the susceptor 126. The gas supply pipe 135 penetrates the electrostatic chuck 131, and the space inside the gas supply pipe 135 communicates with the space between the electrostatic chuck 131 and the wafer W. Furthermore, the susceptor 126 is provided with a plurality of lift pins (not shown) for transferring the wafer W, which can be protruded and retracted from the upper surface of the electrostatic chuck 131.

[0023] A load / unload port 140 for loading the wafer W into the processing chamber 104 and unloading the wafer W from the processing chamber 104 is provided in the side wall 104a of the processing chamber 104, and the load / unload port 140 can be opened and closed by a gate valve G. By controlling the gate valve G to an open state, the wafer W can be loaded and unloaded through the load / unload port 140. In addition, an annular baffle plate 141 having a large number of through holes formed therein is provided between the outer wall of the susceptor support 127 and the side wall 104a of the processing chamber 104.

[0024] An exhaust port 142 is formed in the bottom wall of the processing chamber 104, and an exhaust mechanism 143 is provided in the exhaust port 142. The exhaust mechanism 143 has an exhaust pipe 144 connected to the exhaust port 142, an APC (Auto Pressure Controller) valve 145 that controls the pressure in the processing chamber 104 by adjusting the aperture of the exhaust pipe 144, and a vacuum pump 146 for exhausting the processing chamber 104 via the exhaust pipe 144. The processing chamber 104 is exhausted by the vacuum pump 146, and during the etching process using plasma, the aperture of the APC valve 145 is adjusted to maintain the processing chamber 104 at a predetermined vacuum level.

[0025] The control unit 20 has memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory) and a processor such as a CPU (Central Processing Unit). The processor in the control unit 20 reads and executes programs stored in the memory in the control unit 20 to control each part of the main body 10. Specific processing performed by the control unit 20 will be described later.

[0026] [High frequency power application pattern] Here, the relationship between the application pattern of high frequency power and etching in this embodiment and ALE will be described with reference to FIG. 2 and FIG. 3. The application pattern of high frequency power in ALE shown in FIG. 3 is for comparison with the application pattern of high frequency power in this embodiment. FIG. 2 is a diagram showing an example of the relationship between the application pattern of high frequency power and etching in this embodiment. FIG. 2 shows an application pattern 200, a schematic diagram 201 corresponding to each of phases 1 to 3 of the application pattern 200, and a graph 202 of the etching amount. In FIG. 2, a silicon film is used as the film to be etched 203 on the wafer W, and a silicon nitride film is used as the mask 204. In FIG. 2, a mixed gas of Cl2, O2, and Ar at a predetermined flow rate is used as the process gas.

[0027] The application pattern 200 is a pattern in which the output of the first high frequency power (Bias) and the second high frequency power (Source) is changed in each of phases 1 to 3. In FIG. 2, phases 1 to 3 are represented as Phases I to III. In phase 1, for example, the bias is set to 30 W and the source is set to 100 W, and a first plasma is generated. In phase 2, for example, the bias is set to 300 W and the source is set to 300 W, and a second plasma is generated. In phase 3, for example, the bias and the source are set to 0 W, and the plasma generation is stopped. By repeating phases 1 to 3 of the application pattern 200 as a unit cycle, the film to be etched 203 (silicon film) can be etched to a desired depth. In addition, the unit cycle of the application pattern 200 is on the order of μs to ms.

[0028] Phase 1 is a phase in which the surface of the film to be etched 203 is modified by adsorbing Cl ions and radicals (active species) to the surface of the film to be etched 203 by the first plasma. In phase 1, as shown in the schematic diagram 201, a modified region 205 in which Cl ions and radicals are adsorbed is formed on the surface of the film to be etched 203 at the opening of the mask 204. Phase 2 is a phase in which the modified region 205 formed on the surface of the film to be etched 203 is etched by the second plasma. In phase 2, as shown in the schematic diagram 201, the modified region 205 is etched and a reaction product (by-product) 206 is generated. The reaction product 206 is, for example, SiOCl. Phase 3 is a phase in which the generation of plasma is stopped and the reaction product 206 generated in phase 2 is exhausted. In phase 3, as shown in the schematic diagram 201, the reaction product 206 is separated from the film to be etched 203 and exhausted. A part of the reaction product 206 adheres to the side walls of the recesses of the film 203 to be etched and the mask 204 as deposits.

[0029] Graph 202 shows the etching amount in phases 1 to 3. In phase 1, the first high frequency power (Bias) is applied at 30 W, so that some etching is performed by Cl ions and radicals. In phase 2, the first high frequency power (Bias) is increased to 300 W, so that Cl and O ions and radicals are attracted to the wafer W side, and etching of the modified region 205 progresses. At timing 207, the modified region 205 is entirely etched, and thereafter, the film to be etched 203 is directly etched, so that the slope of the etching amount becomes gentle. In phase 3, the generation of plasma is stopped, so that etching does not progress. Thus, in this embodiment, the application pattern 200 is repeated to etch the film to be etched 203.

[0030] Fig. 3 is a diagram showing an example of the relationship between the application pattern of high frequency power in ALE and etching. Fig. 3 shows an application pattern 210, schematic diagrams 211 corresponding to "steps 1 and 2" of the application pattern 210, and a graph 212 of the etching amount. Also, in Fig. 3, a silicon film is used as the film to be etched 214 on a wafer 213, and a silicon nitride film is used as a mask 215, as in Fig. 2. In Fig. 3, the process gas is switched between "step 1" and "step 2", and a mixture gas of Cl2 and O2 and Ar gas at a predetermined flow rate are used, respectively.

[0031] The application pattern 210 is a pattern for performing ALE by supplying a second high frequency power (Source) in "Step 1" and supplying a first high frequency power (Bias) in "Step 2". In FIG. 3, "Steps 1, 2" are expressed as "Step 1, 2". In "Step 1", for example, the output of the Source is increased (High) and the Bias is set to 0 W, and plasma is generated for modifying the film to be etched 214. In "Step 2", for example, the output of the Bias is decreased (Low) and the Source is set to 0 W, and plasma is generated for etching the modified region. By repeating "Steps 1, 2" of the application pattern 210 as a unit cycle, the film to be etched 214 (silicon film) can be etched to a desired depth. In addition, the unit cycle of the application pattern 210 is on the order of several tens of seconds to several minutes because the process gas is switched in "Steps 1, 2". In other words, the etching process takes longer in ALE than in this embodiment.

[0032] "Step 1" is a step in which Cl and O ions and radicals are adsorbed onto the surface of the film to be etched 214 by plasma generated by a source, thereby modifying the surface. In "step 1", as shown in schematic diagram 211, etchants 216 such as Cl and O ions and radicals are adsorbed onto the surface of the film to be etched 214 at the openings of a mask 215 and onto the side surfaces of the mask 215. At this time, the surface of the film to be etched 214 is modified by the etchant 216. "Step 2" is a step in which the etchant 216 adsorbed onto the surface of the film to be etched 214 is etched with Ar ions by plasma generated by a bias.

[0033] Graph 212 shows the amount of etching 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 wafer W side, and etching of the film to be etched 214 proceeds together with the adsorbed etchant 216. When the adsorbed etchant 216 is gone at timing 217, etching stops. In this way, in ALE, the application pattern 210 is repeated to etch the film to be etched 214.

[0034] [Reaction mechanism] Next, the reaction mechanism in phases 1 and 2 of the application pattern 200 in this embodiment will be described with reference to Figs. 4 to 6. Fig. 4 is a diagram showing an example of the relationship between high frequency power and dissociation cross section. Graph 220 shown in Fig. 4 shows the relationship between the source power and the dissociation cross section for Cl2 gas and O2 gas. As shown in graph 220, when the source is 100 W, that is, in phase 1 of the application pattern 200, Cl2 gas dissociates into radicals Cl * However, O2 gas does not dissociate. On the other hand, when the source is 300 W, that is, in phase 2 of the application pattern 200, both Cl2 gas and O2 gas dissociate into radicals Cl * and O *In phase 2, if Cl2 gas dissociates but O2 gas does not dissociate, the selectivity between the silicon of the film to be etched 203 and the silicon nitride film of the mask 204 cannot be obtained. On the other hand, if a large amount of O2 gas is dissociated, the recess of the film to be etched 203 will have a tapered shape. Therefore, in phase 2, the radical O * In the application pattern 200, the high frequency power is changed between phase 1 and phase 2, so that the amount of radical Cl in each phase is adjusted. * and O * The amount of etching is changed to switch between modification and etching.

[0035] 5 is a diagram showing an example of the state of the wafer in phase 1. As shown in FIG. 5, in phase 1, radicals Cl are ionized on the surface of the film 203 to be etched in the opening of the mask 204 on the wafer W. * is drawn in by the bias. At this time, Cl bonds with Si on the bottom surface 221 of the recess formed in the etched film 203, the surface becomes halogen (Cl)-terminated, and a mixed layer (modified layer) of SiCl is formed. In other words, it becomes self-limited, and adhesion of other than halogen (Cl) is suppressed.

[0036] FIG. 6 is a diagram showing an example of the state of the wafer in phase 2. In phase 2, the reactions shown in FIG. 6(a) to (c) are considered to occur simultaneously. As shown in FIG. 6(a), in phase 2, radicals Cl * and O * is drawn into the surface of the wafer W, but the surface of the bottom surface 221 is terminated with Cl, which suppresses the adhesion of O to the bottom surface 221 and suppresses the oxidation of the surface of the bottom surface 221. Also, as shown in FIG. 6(b), in phase 2, ions and radicals as etchants are drawn into the surface of the wafer W by the bias, the surface of the bottom surface 221 is etched, and SiCl is generated as a reaction product. Also, as shown in FIG. 6(c), in phase 2, the generated SiCl is converted into O *This reacts with the SiOCl to form SiOCl, which adheres as a deposit 222 to the side walls of the recesses of the mask 204 and the film to be etched 203. The deposit 222 protects the side walls of the recesses, thereby contributing to an improvement in the selectivity and bowing, and also contributes to making the bottom surface 221 of the recesses rectangular in shape, since the deposit 222 is unlikely to adhere to the vicinity of the bottom surface 221 of the recesses.

[0037] [Etching method] Next, the etching method according to this embodiment will be described with reference to a flow chart shown in FIG 7, which illustrates an example of the etching process according to this embodiment.

[0038] In the etching method according to this embodiment, the control unit 20 opens the gate valve G of the loading / unloading port 140, and the wafer W having a mask 204 formed on a film 203 to be etched is loaded into the processing chamber 104 and placed on the electrostatic chuck 131 of the susceptor 126. The wafer W is held on the electrostatic chuck 131 by applying a DC voltage to the electrostatic chuck 131. The control unit 20 then closes the gate valve G and controls the exhaust mechanism 143 to exhaust gas from the space S so that the atmosphere in the space S has a predetermined vacuum degree. The control unit 20 also controls a temperature adjustment module (not shown) to adjust the temperature of the wafer W to a predetermined temperature (step S1).

[0039] Next, the control unit 20 starts supplying the process gas (step S2). The control unit 20 supplies a mixed gas of Cl2, O2 and Ar as a process gas containing a halogen-containing gas other than fluorine, an oxygen-containing gas and a rare gas to the processing chamber 104 via the gas supply pipe 124. The supplied mixed gas fills the space S in the processing chamber 104. The halogen-containing gas other than fluorine may be a compound such as HCl, HBr, or HI. In this embodiment, the process gas conditions are the same until the etching process is completed.

[0040] The control unit 20 controls the high frequency power supply 128 and the high frequency power supply 115 to supply a first high frequency power (bias) for bias to the susceptor 126 and a second high frequency power (source) for plasma excitation to the antenna 113. A plasma of the mixed gas is generated by an induction electric field formed in the space S. That is, in the space S, the surface of the film to be etched 203 is modified by supplying radicals of halogen (Cl) generated by the first plasma generated under the first plasma generating conditions to the surface of the film to be etched 203. That is, the control unit 20 performs plasma processing on the wafer W by the first plasma of the process gas generated under the first plasma generating conditions (step S3). The wafer W is exposed to the first plasma, and mainly the bottom surface 221 of the recess of the film to be etched 203 is modified.

[0041] The control unit 20 controls the high frequency power supply 128 and the high frequency power supply 115 to supply a first high frequency power (bias) for bias to the susceptor 126 and a second high frequency power (source) for plasma excitation to the antenna 113. A plasma of a mixed gas is generated by an induction electric field formed in the space S. That is, in the space S, the film to be etched 203 is etched by an etchant generated by a second plasma generated under a second plasma generating condition in which the high frequency power condition and the processing time are different from the first plasma generating condition and the other conditions are the same. That is, the control unit 20 plasma processes the wafer W by a second plasma of a process gas generated under a second plasma generating condition in which the high frequency power condition and the processing time are different from the first plasma generating condition and the other conditions are the same (step S4). The wafer W is exposed to the second plasma, and ions and radicals as an etchant are attracted to the wafer W side by the bias potential, and etching of the film to be etched 203 not masked by the mask 204 proceeds. The time for etching with the second plasma in step S4 is set so that the modified region 205 modified in step S3 is entirely etched and the film to be etched 203 is also slightly etched.

[0042] The control unit 20 determines whether or not the predetermined shape has been obtained by steps S3 and S4 (step S5). When the control unit 20 determines that the predetermined shape has not been obtained (step S5: No), the control unit 20 returns the process to step S3. On the other hand, when the control unit 20 determines that the predetermined shape has been obtained (step S5: Yes), the control unit 20 ends the process. Note that the control unit 20 may include a step between steps S4 and S5 of stopping the supply of the first high frequency power and the second high frequency power, which corresponds to phase 3 of the application pattern 200, to stop the generation of plasma for a predetermined time.

[0043] When the processing is to be ended, the control unit 20 stops the supply of the process gas. The control unit 20 also applies a DC voltage with a reversed positive and negative polarity to the electrostatic chuck 131 to remove electricity, and the wafer W is peeled off from the electrostatic chuck 131. The control unit 20 opens the gate valve G. The wafer W is unloaded from the space S of the processing chamber 104 through the load / unload port 140. In this way, the plasma processing apparatus 100 can perform etching that is faster than the gas switching method and that can simultaneously improve the selectivity and the rectangular shape.

[0044] [Experimental Results] Next, experimental results regarding the rectangular shape of the bottom of the recess in the film to be etched 203 will be described with reference to Fig. 8 and Fig. 9. Fig. 8 is a diagram showing an example of the shape of the bottom. Fig. 9 is a diagram showing an example of the experimental results regarding the relationship between high frequency power and the recess and shape of silicon. As shown in Fig. 8, a shape 230 is formed between the bottom surface 221 of the film to be etched 203 and the side wall of the recess. The lower the height 231 of the shape 230, the more rectangular the recess in the film to be etched 203.

[0045] 9 is a table 240 showing the effects on the amount of etching (silicon recess) of the recess in the film to be etched 203 and the height 231 of the shape 230 when the first high frequency power (Bias) and the second high frequency power (Source) in phase 1 of the application pattern 200 are changed. In addition, in table 240, the upper row shows the case where the second high frequency power (Source) is changed, and the lower row shows the case where the first high frequency power (Bias) is changed. In addition, in FIG. 9, the amount of etching (silicon recess) of the recess in the film to be etched 203 is represented as "Si recess" and the height 231 of the shape 230 is represented as "Shape".

[0046] First, when the second high frequency power (Source) in the upper part is changed, even when the high frequency power is changed from 100W to 600W, the slope of the approximation line (y=-0.0107x+71.017) of the etching amount of the recess is -0.011, and the etching amount of the recess is almost unchanged at about 60 nm. Therefore, it can be seen that the second high frequency power (Source) of phase 1 can supply a sufficient amount of radicals even at 100W. On the other hand, the slope of the approximation line (y=0.0059x+4.3881) of the height 231 of the shape 230 is 0.006, but the range of change of the height 231 is small, so the effect is large, and the height 231 becomes smaller as the high frequency power becomes smaller. In other words, as shown by the frame 241, it can be seen that the shape becomes most rectangular when the second high frequency power (Source) is 100W.

[0047] Next, when the first high frequency power (Bias) is changed in the lower row, even when the high frequency power is changed from 30W to 300W, the slope of the approximation line (y=0.0564x+42.246) of the etching amount of the recess is 0.056, and the etching amount of the recess is about 40 to 60 nm, which does not change much. Therefore, it is understood that the first high frequency power (Bias) of phase 1 does not have much effect on the etching amount of the recess. On the other hand, the slope of the approximation line (y=0.0088x+8.0988) of the height 231 of the shape 230 is 0.009, but the range of change of the height 231 is small, so the effect is large, and the height 231 becomes smaller as the high frequency power becomes smaller. In other words, it can be seen that the shape becomes most rectangular when the first high frequency power (Bias) is 30W, as shown in the frame 242.

[0048] Thus, from the experimental results in Table 240, it is found that 100W is sufficient for the second high frequency power (Source) in phase 1, and that even if the high frequency power is increased any higher, the bottom of the recess will have a tapered shape. It is also found that the lower the first high frequency power (Bias) in phase 1, the more rectangular the bottom of the recess will become, so 30W is best. Therefore, in phase 1 of the application pattern 200 shown in FIG. 2, the second high frequency power (Source) is set to 100W, and the first high frequency power (Bias) is set to 30W.

[0049] [Variations] In the above embodiment, the first plasma and the second plasma are inductively coupled plasma (ICP), but the present invention is not limited thereto. As a plasma generation method, the first plasma and the second plasma may be capacitively coupled plasma (CCP). Regarding the output of high frequency power, the applied power of the high frequency power under the second plasma generation condition may be higher than the applied power of the high frequency power under the first plasma generation condition. Regarding the frequency of the high frequency power, the frequency of the high frequency power under the second plasma generation condition may be higher than the frequency of the high frequency power under the first plasma generation condition. Moreover, the conditions of the high frequency power and the processing time under the first plasma generation condition and the second plasma generation condition may be adjusted according to the depth of the etched film 203.

[0050] In the above embodiment, the etching process is performed on the wafer W having the mask 204 formed on the etching target film 203, but the present invention is not limited to this. For example, an etching process for etching silicon may be performed on a wafer having silicon (Si) surrounded by a silicon nitride film (SiN).

[0051] In the above embodiment, the film to be etched 203 is a silicon film, but is not limited thereto. For example, the film to be etched 203 may be a film containing at least silicon or germanium. The film to be etched 203 may be a single layer film of any one of silicon, germanium, and silicon germanium, or a laminated film of two or more of them.

[0052] In the above embodiment, the mask 204 is a silicon nitride film, but is not limited to this. For example, the mask 204 may use silicon oxide (SiO2) or silicon nitride oxide (SiON) as a silicon compound.

[0053] As described above, according to this embodiment, the control unit 20 executes a) a step of supplying a process gas containing a gas containing a halogen other than fluorine and a gas containing oxygen to a processing vessel (chamber 101, processing chamber 104) in which a mounting table (susceptor 126) for mounting an object to be processed (wafer W) having an etched film is disposed. The control unit 20 executes b) a step of plasma processing the object to be processed by a first plasma of the process gas generated under a first plasma generating condition. The control unit 20 executes c) a step of plasma processing the object to be processed by a second plasma of the process gas generated under a second plasma generating condition in which the high frequency power condition and the processing time are different from the first plasma generating condition and the other conditions are the same. The control unit 20 executes d) a step of repeating b) and c). As a result, etching can be performed at a higher speed than the gas switching method and at the same time as the etching method in which the selectivity and the rectangular shape can be improved.

[0054] In addition, according to this embodiment, in step b), halogen radicals generated by the first plasma are supplied to the surface of the film to be etched. In step c), the film to be etched is etched by the etchant generated by the second plasma. As a result, etching can be performed at a higher speed than the gas switching method, while improving both the selectivity and the rectangular shape.

[0055] According to the present embodiment, the second plasma generating condition is a condition that generates a bias potential on the object to be processed, so that the film to be etched can be etched.

[0056] Furthermore, according to the present embodiment, the amount of oxygen radicals generated by the first plasma in b) is smaller than the amount of oxygen radicals generated by the second plasma in c), which makes it possible to prevent the bottom surface of the recess in the etched film from becoming tapered.

[0057] According to the present embodiment, the control unit 20 executes e) a step of not generating plasma. In addition, d) repeats b), c), and e) in the order of b), c), and e). As a result, the generated reaction products can be discharged.

[0058] In addition, according to the present embodiment, the conditions of the process gas introduced in step e) are the same as the conditions of the process gas introduced in steps b) and c), thereby making it possible to suppress a decrease in throughput due to switching of the process gas.

[0059] Furthermore, according to this embodiment, the film to be etched is a film containing at least silicon or germanium, and as a result, these films can be etched while achieving both an improvement in the selectivity and the rectangular shape.

[0060] In addition, according to the present embodiment, the film to be etched is a single layer film or a laminated film of two or more of silicon, germanium, and silicon germanium. As a result, these films can be etched while improving both the selectivity and the rectangular shape.

[0061] According to the present embodiment, the object further has a mask made of a silicon compound on the film to be etched. The film to be etched is etched through the openings of the mask. As a result, the film to be etched can be etched while achieving both the selectivity and the improvement of the rectangular shape according to the openings of the mask.

[0062] According to the present embodiment, the object to be processed has a first region made of a film to be etched and a second region made of a silicon compound, and the first region is selectively etched with respect to the second region. As a result, the first region can be etched while achieving both an improvement in the selectivity and the rectangular shape.

[0063] According to the present embodiment, the silicon compound is at least one of silicon oxide, silicon nitride, and silicon oxynitride, and as a result, the first region can be etched while improving both the selectivity and the rectangular shape.

[0064] In addition, according to the present embodiment, the high frequency power conditions and the processing time in the first plasma generating condition and the second plasma generating condition are adjusted according to the depth of the etched film, so that the range of the protective film formed by the reaction product (deposit) can be controlled.

[0065] Furthermore, according to this embodiment, the applied power of the high frequency power under the second plasma generating condition is higher than the applied power of the high frequency power under the first plasma generating condition, so that the modification (adsorption) step and the etching step can be repeated.

[0066] Furthermore, according to this embodiment, the frequency of the high frequency power under the second plasma generating condition is higher than the frequency of the high frequency power under the first plasma generating condition, which makes it possible to repeat the modification (adsorption) step and the etching step.

[0067] Furthermore, according to this embodiment, the first plasma and the second plasma are inductively coupled plasma or capacitively coupled plasma, so that the modification (adsorption) step and the etching step can be repeated.

[0068] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects, and may be omitted, substituted, or modified in various ways without departing from the spirit and scope of the appended claims.

[0069] In the above embodiment, the plasma source is described as an inductively coupled plasma (ICP), but is not limited thereto. For example, any plasma source such as a capacitively coupled plasma (CCP), a microwave plasma, or a magnetron plasma may be used as the plasma source.

[0070] In the above embodiment, the film to be etched is a silicon film, but the present invention is not limited to this. For example, the present invention can be applied to etching using a silicon-containing film that has a selectivity with respect to the film to be etched and is different from the film to be etched as a mask, such as a silicon oxide film or a silicon nitride film. [Explanation of symbols]

[0071] 10. Main Unit 20 Control section 100 Plasma treatment device 101 Chamber 103 Antenna Room 104 Processing Room 115,128 High frequency power supply 120 Gas supply mechanism 124 Gas supply pipe 126 Susceptor 131 Electrostatic Chuck S space W wafer

Claims

1. A substrate processing method in a substrate processing apparatus, comprising: a) supplying a process gas containing a gas containing a halogen except for fluorine and a gas containing oxygen to a processing vessel in which a stage for placing a processing object having a film to be etched is disposed; b) plasma processing the workpiece with a first plasma of the process gas generated under first plasma generating conditions; c) plasma processing the workpiece with a second plasma of the process gas generated under second plasma generating conditions, the second plasma generating conditions being different from the first plasma generating conditions in terms of high frequency power and processing time, and other conditions being the same; d) not generating a plasma; e) repeating steps b), c), and d) in the order of steps b), c), and d); A substrate processing method comprising the steps of:

2. A substrate processing method in a substrate processing apparatus, comprising: a) supplying a process gas containing a gas containing a halogen except for fluorine and a gas containing oxygen to a processing vessel in which a stage for placing a processing object having a film to be etched is disposed; b) plasma processing the workpiece with a first plasma of the process gas generated under first plasma generating conditions; c) plasma processing the workpiece with a second plasma of the process gas generated under second plasma generating conditions that are different from the first plasma generating conditions in terms of high frequency power and processing time; d) not generating a plasma; e) repeating steps b), c), and d) in the order of steps b), c), and d); A substrate processing method comprising the steps of:

3. The step b) supplies the halogen radicals generated by the first plasma to a surface of the film to be etched; The step c) includes etching the film to be etched with an etchant generated by the second plasma. The substrate processing method according to claim 1 .

4. The second plasma generation condition is a condition under which a bias potential is generated on the workpiece. The substrate processing method according to any one of claims 1 to 3.

5. In the step b), the amount of the oxygen radicals generated by the first plasma is less than the amount of the oxygen radicals generated by the second plasma in the step c). The substrate processing method according to any one of claims 1 to 4.

6. The conditions of the process gas introduced in step d) are the same as the conditions of the process gas introduced in steps b) and c); The substrate processing method according to any one of claims 1 to 5.

7. The film to be etched is a film containing at least silicon or germanium. The substrate processing method according to any one of claims 1 to 6.

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

9. the workpiece further has a mask made of a silicon compound on the film to be etched, The film to be etched is etched through the openings of the mask. The substrate processing method according to any one of claims 1 to 8.

10. the workpiece has a first region made of a film to be etched and a second region made of a silicon compound, and the first region is selectively etched with respect to the second region; The substrate processing method according to any one of claims 1 to 8.

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

12. The conditions of high frequency power and processing time in the first plasma generating condition and the second plasma generating condition are adjusted according to the depth of the etched film. The substrate processing method according to any one of claims 1 to 11.

13. The applied power of the high frequency power under the second plasma generating condition is higher than the applied power of the high frequency power under the first plasma generating condition. The substrate processing method according to any one of claims 1 to 12.

14. The frequency of the high frequency power under the second plasma generating condition is higher than the frequency of the high frequency power under the first plasma generating condition. The substrate processing method according to any one of claims 1 to 12.

15. The first plasma and the second plasma are inductively coupled plasma or capacitively coupled plasma. The substrate processing method according to any one of claims 1 to 14.

16. A substrate processing apparatus, comprising: A processing vessel; a mounting table disposed in the processing chamber and configured to mount an object to be processed having a film to be etched thereon; A control unit, a) the control unit is configured to control the substrate processing apparatus to supply a process gas including a gas containing a halogen other than fluorine and a gas containing oxygen to the processing vessel; b) the control unit is configured to control the substrate processing apparatus to plasma process the workpiece with a first plasma of the process gas generated under a first plasma generating condition; c) the control unit is configured to control the substrate processing apparatus to plasma process the workpiece with a second plasma of the process gas generated under second plasma generating conditions, the second plasma generating conditions being different from the first plasma generating conditions in terms of high frequency power and processing time, and other conditions being the same; d) the control unit is configured to control the substrate processing apparatus so as not to generate plasma; e) the control unit is configured to control the substrate processing apparatus to repeat the steps b), c), and d) in the order of the steps b), c), and d); Substrate processing equipment.

17. A substrate processing apparatus comprising: A processing vessel; a mounting table disposed in the processing chamber and configured to mount an object to be processed having a film to be etched thereon; A control unit, a) the control unit is configured to control the substrate processing apparatus to supply a process gas including a gas containing a halogen other than fluorine and a gas containing oxygen to the processing vessel; b) the control unit is configured to control the substrate processing apparatus to plasma process the workpiece with a first plasma of the process gas generated under a first plasma generating condition; c) the control unit is configured to control the substrate processing apparatus to plasma process the workpiece with a second plasma of the process gas generated under second plasma generating conditions that are different from the first plasma generating conditions in terms of high frequency power and processing time; d) the control unit is configured to control the substrate processing apparatus so as not to generate plasma; e) the control unit is configured to control the substrate processing apparatus to repeat the steps b), c), and d) in the order of the steps b), c), and d); Substrate processing equipment.

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