Etching method and etching apparatus

Abstract

An etching method is provided that inhibits the generation of deep loading and promotes etching. The etching method includes: (a) a process of providing a substrate including an etched layer on a substrate support pedestal disposed in a processing chamber; (b) a process of setting a temperature of the substrate support pedestal; (c) a process of generating a plasma from an etching gas; (d) a process of increasing a temperature of the substrate; (e) a process of decreasing the temperature of the substrate; and (f) a process of repeating the process of (d) and the process of (e) a predetermined number of times.

Description

Technical Field

[0001] This invention relates to etching methods and etching apparatus. Background Technology

[0002] A method has been proposed to form pores in a silicon oxide film by etching at a low temperature (see, for example, Patent Document 1). The higher the aspect ratio, the easier it is for the etching rate to decrease because the reaction products generated by etching accumulate at the bottom of the pores and are difficult to volatilize; this is known as depth loading.

[0003] <Prior art documents>

[0004] <Patent Documents>

[0005] Patent Document 1: Japanese Patent Application Publication No. 7-22393 Summary of the Invention

[0006] <Problem to be solved by this invention>

[0007] This invention provides a technique that can suppress the generation of deep loading and promote etching.

[0008] <Methods for solving problems>

[0009] According to one aspect of the present invention, an etching method is provided, comprising: (a) a step of providing a substrate including an etched film on a substrate support disposed in a processing chamber; (b) a step of setting the temperature of the substrate support; (c) a step of generating plasma by etching gas; (d) a step of raising the temperature of the substrate; (e) a step of lowering the temperature of the substrate; and (f) a step of repeating the steps of (d) and (e) a predetermined number of times.

[0010] <The Effects of the Invention>

[0011] According to one aspect, it is possible to suppress the generation of deep loading and promote etching. Attached Figure Description

[0012] Figure 1 This is a diagram illustrating an example of an etching model of an implementation method.

[0013] Figure 2 This is a graph showing an example of experimental results based on the etching methods of embodiments 1 and 2.

[0014] Figure 3 This is a flowchart illustrating an example of the etching method of Embodiment 3.

[0015] Figure 4 This is a timeline illustrating an example of the etching method of Embodiment 4.

[0016] Figure 5 It is used for explanation Figure 4 A diagram of the etching method.

[0017] Figure 6 This is a timeline illustrating an example of the etching method of Embodiment 5.

[0018] Figure 7 This is a timeline illustrating an example of the etching method of Embodiment 6.

[0019] Figure 8 This is a cross-sectional schematic diagram illustrating an example of an etching apparatus according to an embodiment. Detailed Implementation

[0020] Hereinafter, the embodiments for carrying out the present invention will be described with reference to the accompanying drawings. In the drawings, the same reference numerals are given to the same constituent parts, and sometimes repeated descriptions are omitted.

[0021] [Deep Loading and Etching]

[0022] First, refer to Figure 1 The reduction in etching rate due to depth loading is explained. Figure 1 This is a diagram illustrating an example of an etching model (structure) of an embodiment. In the etching model of the embodiment, the substrate W includes an etchable film 3 and a mask 2. The etchable film 3 is etched by a pattern formed on the mask 2, thereby forming holes or grooves (hereinafter referred to as recesses 4) in the etched film 3.

[0023] If the aspect ratio of the recess 4 becomes approximately 20 or higher as etching time progresses, by-products generated during etching become difficult to remove from the bottom of the recess 4, resulting in a decrease in the etching rate—a phenomenon known as deep loading. The deep loading phenomenon becomes significant when the aspect ratio is 50 or higher. Hereinafter, in this specification, aspect ratios of 20 or higher will be referred to as high aspect ratios, and aspect ratios less than 20 will be referred to as low aspect ratios. At the bottom of a high aspect ratio recess 4, the pressure becomes higher than at the bottom of a low aspect ratio recess 4, thus the effect of deep loading is greater.

[0024] In, for example, HARC (High Aspect Ratio Contact), the deeper the recess 4, the more difficult it is for the reaction products in the recess 4 to be discharged, resulting in deep loading and deteriorating productivity. In addition, the shape of the bottom of the recess 4 also deteriorates.

[0025] Figure 1 (a) schematically illustrates etching at a substrate temperature lower than room temperature. Figure 1 (b) schematically shows the etching when the temperature of the substrate is relatively high (above normal temperature). When the temperature of the substrate is lower than normal temperature, the adsorption amount of the etchant to the substrate (the generation amount of reactive species) increases. In this case, the etching rate (E / R) in the low aspect ratio (low AR) region is relatively high. In addition, since the etching is promoted, the generation amount of the reaction product 5 generated during the etching is relatively large, and the discharge rate of the reaction product 5 from the concave portion 4 is slow. Therefore, as Figure 1 shown in the model (structure) of (a), it is difficult for the reaction product 5 to be discharged, and depth loading is significant in the high aspect ratio region. In addition, the shape of the concave portion 4 deteriorates, and there is a concern that the bottom of the concave portion 4 is sharp, the side wall of the concave portion 4 is not perpendicular, and the shape of the concave portion 4 is distorted. However, it is difficult to generate an arcuate bending shape (Bowing) in which the side wall of the concave portion 4 widens with respect to the opening width (Japanese original text: 間口) of the etched film 3.

[0026] If the temperature of the substrate becomes higher, the reaction product 5 becomes more volatile. As Figure 1 shown in the model of (b), the reaction product 5 is discharged from the concave portion 4, but the adsorption amount of the etchant to the bottom of the concave portion 4 decreases, and the etching rate cannot be increased. In addition, the bottom of the concave portion 4 is flat and the side wall of the concave portion 4 is close to being substantially perpendicular. However, an arcuate bending shape 6 is likely to occur in the concave portion 4.

[0027] [Embodiment]

[0028] As described above, the generation of depth loading, the level of the etching rate, and the shape of the concave portion 4 are determined by the balance between the promotion of etching (generation of the reaction product 5) and the discharge of the reaction product 5 from the concave portion 4. Therefore, in an etching method of one embodiment, an etching technique is provided that suppresses the generation of depth loading and promotes etching even in a high aspect ratio region, and suppresses the tapering of the tip of the concave portion 4 to make it vertical.

[0029] Figure 2 is a graph showing an example of the experimental results of an etching method of one embodiment. In this experiment, the etching device 1 described later (refer to Figure 8 ) was used, and the substrate W including the etched film was placed on the substrate support table 20 disposed in the processing chamber 10 for etching. In the experiment, the etching gas was supplied into the processing chamber 10 under the following conditions, and the temperature of the substrate support table 20 was controlled for etching.

[0030] [Conditions]

[0031] Etched film: A laminated film in which a silicon oxide film (SiOx) and a silicon nitride film (SiN) are alternately laminated

[0032] Etching gases: halogen-containing gases, fluorocarbon gases

[0033] Temperature of substrate support stage: -40℃

[0034] In this experiment, a case where etching was performed under controlled high pressure (27 mTorr: 3.6 Pa) within the processing chamber was used as a reference example. Figure 2 The curve e is shown. In contrast, the case where etching was performed under the above conditions with a lower pressure (10 mTorr: 1.3 Pa) within the processing chamber is illustrated in Embodiment 1. Figure 2 The curve f is shown. Furthermore, in Embodiment 2, when etching is performed under the above conditions with a relatively high pressure (27 mTorr) within the processing chamber, 200 sccm of argon and 2 sccm of O2 are added to the etching gas to dilute the etching gas. Figure 2 The curve g is shown. It should be noted that O2 gas is added to the etching gas to expand the opening width of the recess 4. O2 gas may not be added to dilute the etching gas.

[0035] Figure 2 The horizontal axis represents the process time (etching time), and the vertical axis represents the Interval E / R. The Interval E / R is expressed by the following formula, which corresponds to the etching rate.

[0036] Interval E / R = D n -D n-1 / (t n -t n-1 )

[0037] In the formula, n represents the measurement point of the etching rate, t represents time, and D represents the depth of the recess 4. For the measurement point where n=1, the time t is set to t0=0 (min) and the depth D is set to D0=0 (nm) for calculation.

[0038] As a result, in curve e of the reference example, the Interval E / R decreases sharply as the process time progresses. This is attributed to the fact that in the initial stage of the process... Figure 8 The substrate support stage 20 has a low temperature of -40°C, resulting in a larger supply of etchant and thus a higher Interval E / R. Furthermore, while a higher Interval E / R leads to an increase in the amount of reaction products generated, the recess 4 deepens over time, and the pressure within the processing chamber 10 increases, making it difficult for the reaction products to be discharged from the recess 4. Therefore, it is believed that a longer process time results in deeper loading, significantly reducing the Interval E / R (and consequently, the etching rate).

[0039] In contrast, in curve f of Embodiment 1 and curve g of Embodiment 2, the sharp decrease in Interval E / R as seen in the reference example is not observed, and the reduction in etching rate relative to process time becomes more gradual. That is, in curve f of Embodiment 1, since the pressure within the processing chamber 10 is controlled to be lower than in the reference example, the reaction products are easily discharged from the bottom of the recess 4, thereby suppressing the generation of deep loading and the reduction in etching rate becomes more gradual. Furthermore, in curve g of Embodiment 2, the etchant is diluted with argon gas, and compared to the reference example, the amount of etchant supplied to the substrate is reduced, thereby reducing the amount of reaction products generated, which in turn suppresses the generation of deep loading and the reduction in etching rate becomes more gradual.

[0040] In the reference example, the Interval E / R decreases sharply as the process time progresses. Therefore, when etching the film 3 to be etched is performed, for example, in a mask 2 pattern with mixed diameters and widths, there is a concern that the difference in etching rates of the recesses 4 with different diameters and widths will increase. On the other hand, the depressurization in the etching method of Embodiment 1 and the dilution of the etching gas in the etching method of Embodiment 2 reduce the variation in etching rates of the recesses 4 with different diameters and widths. Therefore, according to the etching methods of Embodiments 1 and 2, even when etching the film 3 to be etched in a mask 2 pattern with mixed diameters and widths, for example, the difference in etching rates of the recesses 4 with different diameters and widths can be reduced, thereby mitigating the decrease in etching rate caused by the passage of process time.

[0041] However, in the etching methods of Embodiments 1 and 2, the overall etching rate is reduced compared to the reference example, especially in the early stages of etching (in areas with low aspect ratios), where a tendency for a lower etching rate can be observed. Therefore, the inventors have derived an etching method that does not reduce the overall etching rate and does not produce a sharp decrease in the etching rate. Figure 3 This is a flowchart illustrating an example of the etching method of Embodiment 3. In this specification and the accompanying drawings, a high-frequency (RF) frequency supplied to the substrate support stage 20 or an electrode opposite to the substrate support stage 20 and having a frequency primarily conducive to plasma generation is referred to as HF. Conversely, a high-frequency frequency supplied to the substrate support stage 20 and having a frequency primarily conducive to the introduction of ions in the plasma is referred to as LF. The frequency of HF is higher than the frequency of LF. HF and LF can each be supplied in a pulsed manner. HF power is also referred to as source power, and LF power is also referred to as bias power.

[0042] like Figure 3As shown, the etching method of Embodiment 3 includes steps S1 to S6. First, in step S1, a substrate W including the etched film 3 is provided on a substrate support 20 disposed within the processing chamber 10. Next, in step S2, the temperature of the substrate support 20 is set. In one example, it is preferable to set the temperature of the substrate support 20 to between -40°C and 20°C in step S2. For example, the temperature of the substrate support 20 is set to -40°C. In step S2, the temperature of the substrate can be set instead of the temperature of the substrate support 20. It is preferable to set the temperature of the substrate to between -40°C and 20°C. Here, by supplying a heat transfer gas between the upper surface of the substrate support 20 and the back surface of the substrate, the temperature of the substrate support 20 and the temperature of the substrate can be set to be approximately the same.

[0043] Next, in step S3, HF power (high-frequency power for plasma generation) is supplied to generate plasma from the etching gas supplied to the processing chamber 10. Next, in step S4, the temperature of the substrate W is raised, and the generated plasma is used to etch the film 3 to be etched. Next, in step S5, the temperature of the substrate W is lowered, and the generated plasma is used to etch the film 3 to be etched. Here, in step S4, bias power (LF in one example) is supplied to the substrate support stage 20. In step S5, bias power (LF in one example) is not supplied to the substrate support stage 20. Next, in step S6, it is determined whether the steps S4 and S5 have been repeated a predetermined number of times. The predetermined number is set to an integer greater than or equal to 1. In step S6, the steps S4 and S5 are repeated until it is determined that the predetermined number of repetitions has been achieved; when the predetermined number of repetitions is determined, the process ends. It should be noted that the steps S4 and S5 can be performed in reverse order, i.e., step S5 is performed before step S4.

[0044] According to the etching method of Embodiment 3, in S3, plasma is generated from the etching gas, and the etchant is supplied (adsorbed) to the substrate surface from the generated plasma, thereby performing etching. At the same time, reaction products (etching byproducts) are generated around the bottom periphery of the recess 4.

[0045] Next, in step S4, the temperature of the substrate W is raised to a pre-set temperature to promote the discharge of the generated reaction products from the recess 4. For example, in step S4, the temperature of the substrate is raised to the temperature at which the reaction products volatilize. In step S5, the substrate temperature is lowered again to perform etching. In step S5, since the etchant is easily adsorbed when the substrate temperature is low, the temperature of the substrate is lowered to a sufficient amount of etchant adsorbed at the substrate temperature. In step S5, the substrate temperature can be set to between -40°C and 20°C. The substrate temperature in step S4 is higher than the substrate temperature set in step S5. Preferably, the temperature difference between the substrates in step S4 and step S5 is 10°C or more. In step S4, the substrate temperature can be set to between 10°C and 30°C.

[0046] [Implementation Methods 4-6]

[0047] Next, for Figure 3 The etching method shown involves repeated processing of steps S4 and S5. Three methods from Embodiments 4 to 6, which are specific embodiments of Embodiment 3, will be described. In Embodiments 4 to 6, the etching process involving repeated processing of steps S4 and S5 is illustrated. Figure 3 The example shown is that step S4 is executed after step S5, but step S5 can also be executed after step S4.

[0048] Examples of HF frequencies include 40MHz, 60MHz, and 100MHz, while examples of LF frequencies include 400kHz, 3MHz, and 13MHz, but these are not limited to these. The bias voltage used to facilitate ion introduction is not limited to high frequency (RF); it can also be a DC voltage with a negative polarity pulse frequency. In this case, the pulse frequency can be between 100kHz and 800kHz; 400kHz is an example. For high-frequency power (RF power), HF power (high-frequency power for plasma generation) can be set to 5kW, and LF power (high-frequency power for bias voltage) can be set to 10kW, etc. Generally, the power used increases with the increase in aspect ratio.

[0049] <Implementation Method 4>

[0050] First, refer to Figure 4 as well as Figure 5 An example of the etching method in Embodiment 4, which is an example of Embodiment 3, will be described. Figure 4 This is a timeline illustrating an example of the etching method of Embodiment 4. Figure 5 It is used for explanation Figure 4 A diagram of the etching method.

[0051] In the etching method of Embodiment 4, HF is a continuous wave, which is supplied to the substrate support stage 20 or the electrode opposite to the substrate support stage 20 between etching operations. Figure 8 (Nozzle 25). Using HF electricity, self-etching gas generates plasma, and the etched film 3 on the substrate W is etched under the action of plasma.

[0052] In the etching method of Embodiment 4, LF is a pulse wave, which is supplied to the substrate support stage 20 between etching operations, thereby controlling the temperature of the substrate. In Embodiment 4, by... Figure 4 During period A, LF is controlled to be off or low, thereby executing... Figure 3 Step S5. For example, during period A of the first cycle, LF is controlled to be off or low level. Since the amount of ions introduced into the plasma into the substrate is reduced, the heat introduced from the plasma is reduced. As a result, the temperature of the substrate decreases. This increases the adsorption (supply) of the etchant to the recess 4. That is, since the etchant is more easily adsorbed when the substrate temperature is lower, the temperature of the substrate is reduced to a sufficient amount of etchant adsorbed at the substrate temperature, thereby promoting etching.

[0053] Additionally, execution is achieved by controlling LF to be on or high during period B. Figure 3 Step S4. During period B of the first cycle, LF is controlled to be on or high level. Due to the increased amount of ions introduced into the substrate from the plasma, the heat from the plasma increases. As a result, the temperature of the substrate rises. Consequently, reaction product 5 becomes easier to detach. That is, as... Figure 5 As shown in Step 2 of (b), raising the temperature of the substrate W to a pre-set temperature promotes the removal (detachment) of the etch-based reaction products. However, the supply of etchant is reduced.

[0054] Therefore, during period A of the second cycle, LF is again controlled to be off or low. As a result, the temperature of the substrate decreases again, and the adsorption of etchant into recess 4 increases, thereby promoting etching.

[0055] During period B, the LF power is controlled to raise the substrate temperature to a temperature range where the reaction product 5 evaporates during etching and can be removed from the recess 4. This promotes the removal (detachment) of the reaction product. It should be noted that the substrate support stage (mounting stage) is maintained at approximately -40°C in one example. Therefore, the substrate temperature is saturated by varying with a certain time constant τ during periods A and B, respectively. Since the substrate support stage (mounting stage) is maintained at approximately -40°C in one example, the substrate in contact with the substrate support stage is cooled by heat conduction based on the temperature of the substrate support stage. Furthermore, the substrate temperature is controlled by switching the LF power on and off. Specifically, control is performed by increasing the temperature when the LF power is on and decreasing the temperature when it is off. When the temperature rises after the LF power is on, it becomes a fixed temperature after a certain period of time. The approximate time from when the LF power is on until it becomes a fixed temperature is called the time constant. Saturation means stabilization at an approximately fixed temperature.

[0056] As described above, in Embodiment 4, by alternately repeating the cooling of the substrate during period A and the heating of the substrate during period B in each cycle, the adsorption and etching of the etchant are promoted during period A, and the discharge (removal) of the reaction product 5 is promoted during period B. By repeating this cycle a predetermined number of times, alternating the promotion of etchant adsorption and etching with the discharge (removal) of the reaction product, the trade-off between the promotion of etching and the generation of deep loading is eliminated. Therefore, according to the etching method of Embodiment 4, the generation of deep loading can be suppressed, and etching can be promoted. As a result, productivity can be improved. Furthermore, the generation of arc-shaped bending and twisting in the shape of the recess 4 is suppressed, thereby enabling the sidewalls of the recess 4 to be formed approximately vertical.

[0057] In one example, the period of a cycle can be 0.01 milliseconds to 10 seconds (frequency 0.1 Hz to 100 kHz), 1 millisecond to 1 second (frequency 1 Hz to 1 kHz), or 0 milliseconds to 500 milliseconds (frequency 100 Hz to 2 Hz). Preferably, the time during which the LF is controlled to be on or high is relative to the time of one cycle, i.e., the duty cycle of period B / (period A + period B), is 10% to 70%, more preferably 30% to 50%. The above-mentioned HF frequency, LF frequency, cycle period (frequency), and duty cycle also apply to embodiments 5 and 6 described later. It should be noted that, regarding the relationship between "high level" and "low level" in this specification, "high level" refers to a level (power level) that is higher than "low level". In other words, when "high level" is set as the first level and "low level" is set as the second level, the first level is higher than the second level.

[0058] <Implementation Method 5>

[0059] Next, refer to Figure 6 An example of the etching method in Embodiment 5, namely one example of Embodiment 3, will be described. Figure 6 This is a time diagram illustrating an example of the etching method of Embodiment 5. The difference between Embodiment 5 and Embodiment 4 is that the HF is pulse-controlled in the etching method of Embodiment 5.

[0060] The pulse control of LF is the same as in Embodiment 4, where LF is controlled to be off or low level during period A, and to be on or high level during period B. In addition, in Embodiment 5, HF is controlled to be on or high level during period A, and to be off or low level during period B. It should be noted that HF ​​is supplied to the substrate support stage 20 or the electrode opposite to the substrate support stage 20.

[0061] Therefore, during period A, LF is controlled to be off or at a low level, reducing the amount of ions in the plasma introduced to the substrate, thereby reducing the heat introduced from the plasma. As a result, the temperature of the substrate decreases. This promotes the adsorption (supply) of the etchant to the recess 4 and etching. Moreover, during period A, HF is controlled to be on or at a high level. As a result, during period A, plasma generation is promoted, the amount of etchant adsorbed increases, and etching is promoted. In contrast, during period B, LF is controlled to be on or at a high level, increasing the amount of ions in the plasma introduced to the substrate and thus increasing the heat introduced from the plasma, thereby raising the temperature of the substrate. This promotes the removal (detachment) of reaction products based on etching. Moreover, during period B, HF is controlled to be off or at a low level. As a result, the amount of plasma generated decreases, the amount of etchant adsorbed to the recess 4 decreases, and the amount of reaction products generated decreases.

[0062] As described above, in Embodiment 5, in addition to pulse control of LF, pulse control of HF is used to control the supply of etchant, the promotion of etching, and the removal of reaction products. That is, the increase in etchant supply and the promotion of etching based on substrate cooling during period A are alternately repeated, as are the decrease in etchant supply and the removal (detachment) of reaction products based on substrate heating during period B. This improves the removal efficiency of reaction products 5, suppresses the generation of deep loading, and promotes etching. Furthermore, it allows for further improvement of the shape of the recess 4.

[0063] It should be noted that in embodiments 4 and 5, examples of setting the waveforms of LF and / or HF as rectangular waves are given, but this is not the only possibility. The waveforms of LF and HF are not only rectangular waves, but can also be approximately rectangular waves that include at least one of a gradual rise or a gradual fall. The same applies in embodiment 6.

[0064] <Implementation Method 6>

[0065] Next, refer to Figure 7 An example of the etching method in Embodiment 6, namely Embodiment 3, will be described. Figure 7 This is a timeline illustrating an example of the etching method of Embodiment 6. In the etching method of Embodiment 6, as... Figure 7 As shown in (a) and (b), the supply of the heat transfer medium between the substrate support 20 and the substrate W is different from Embodiment 5, where the pressure varies in a pulsed manner. Furthermore, as... Figure 7 As shown in (b), the heat transfer medium supplied in a pulsed manner to the space between the substrate support 20 and the substrate W, and to the space provided on the substrate support 20 (described later) Figure 8The adsorption voltage of the electrode 106a of the electrostatic chuck 106 is supplied in Embodiment 6, which differs from Embodiment 5. It should be noted that in Embodiment 6, the pulse control of LF and HF is the same as in Embodiment 5, and LF can also be pulse controlled in the same way as in Embodiment 4, while HF is set to a continuous wave.

[0066] The supply of the heat transfer medium improves the heat transfer efficiency between the substrate support 20 and the substrate W. Therefore, by controlling the flow rate of the heat transfer medium, the pressure between the substrate support 20 and the substrate W can be changed, thereby altering the temperature of the substrate. It should be noted that although He gas is used as the heat transfer medium in Embodiment 6, other inert gases can also be used.

[0067] In embodiment 6, specifically, during period A, LF is controlled to be off or low level, and during period B, LF is controlled to be on or high level. Additionally, during period A, HF is controlled to be on or high level, and during period B, HF is controlled to be off or low level.

[0068] In addition, in embodiment 6, the pressure (He Back Pressure) between the back surface of the substrate W and the surface of the substrate support 20 is controlled. As an example, a heat transfer medium such as He gas is supplied from the heat transfer gas supply source 85 to the area between the back surface of the substrate W and the surface of the substrate support 20 via the heat transfer gas line 130, and its flow rate is controlled to be high or low. Furthermore, a temperature regulating medium (temperature regulating fluid) is supplied via... Figure 8 The chiller 107 shown is controlled to the desired temperature. The temperature-regulating medium is output from the chiller 107, flows into the flow path inlet 104b, passes through the flow path 104a, and exits from the flow path outlet 104c, then returns to the chiller 107. In embodiment 6, while the temperature-regulating medium supplied from the chiller 107 flows in the flow path 104a, the pressure between the back surface of the substrate W and the surface of the substrate support 20 is controlled by changing the flow rate of the He gas.

[0069] When the temperature of the temperature-regulating medium controlled by the chiller 107 is higher than the preset threshold temperature, such as Figure 7As shown in (a), by controlling the flow rate of He gas to a low level during period A, the pressure between the back surface of the substrate W and the surface of the substrate support 20 decreases. This reduces heat transfer efficiency during period A, making it difficult for the temperature of the substrate support 20, heated by the temperature-regulating medium flowing in the flow path of the substrate support 20, to be transferred to the substrate W, thus lowering the temperature of the substrate W. This promotes the adsorption (supply) of the etchant to the recess 4 and etching. On the other hand, by controlling the flow rate of He gas to a high level during period B, the pressure between the back surface of the substrate W and the surface of the substrate support 20 increases. This improves heat transfer efficiency during period B, making it easier for the temperature of the substrate support 20, heated by the temperature-regulating medium, to be transferred to the substrate W, thus raising the temperature of the substrate. This promotes the venting (detachment) of the reaction product 5 from the recess 4.

[0070] When the temperature of the temperature-regulating medium controlled by the chiller 107 is lower than the preset threshold temperature, such as Figure 7 As shown in (b), by controlling the flow rate of He gas to be high during period A, the pressure between the back side of the substrate W and the surface of the substrate support 20 is increased. This improves heat transfer efficiency during period A, making it easier for the temperature of the substrate support 20, which is cooled by the temperature-regulating medium, to be transferred to the substrate W, thereby lowering the substrate temperature. This promotes the adsorption of the etchant into the recess 4 and etching. On the other hand, by controlling the flow rate of He gas to be low during period B, the pressure between the back side of the substrate W and the surface of the substrate support 20 is reduced. This decreases heat transfer efficiency during period B, making it difficult for the temperature of the substrate support 20 to be transferred to the substrate W, thereby raising the substrate temperature. This promotes the discharge of the reaction product 5 from the recess 4.

[0071] Moreover, it can Figure 8 The adsorption voltage of the electrode 106a of the electrostatic chuck 106 is controlled to be either high or low. By changing the adsorption voltage of the electrostatic chuck 106, the heat transfer characteristics between the electrostatic chuck 106 and the substrate W are altered, thereby allowing adjustment of the temperature of the substrate W. For example, setting the adsorption voltage of the electrostatic chuck 106 to a higher value increases thermal conductivity, while setting it to a lower value decreases thermal conductivity. This allows for adjustment of the temperature of the substrate W.

[0072] For example, in Figure 7In (b), the adsorption voltage is controlled at a high level during period A. This increases heat transfer efficiency during period A, making it easier for the temperature of the substrate support 20, cooled by the temperature-regulating medium, to be transferred to the substrate W, thereby lowering the substrate temperature. This promotes the adsorption of the etchant into the recess 4 and etching. During period B, the adsorption voltage is controlled at a low level. This reduces heat transfer efficiency during period B, making it difficult for the temperature of the substrate support 20, cooled by the temperature-regulating medium, to be transferred to the substrate W, thereby raising the substrate temperature. This promotes the venting of the reaction product 5 from the recess 4. The periods during which the adsorption voltage is controlled at a high level by controlling the temperature of the temperature-regulating medium alternate with periods during which it is controlled at a low level. Although not shown in the figure, it is... Figure 7 In (a), when the temperature of the substrate support stage 20 is being heated by the temperature regulating medium, the adsorption voltage is controlled to a low level during period A and to a high level during period B.

[0073] By using at least one of the above-described LF control, HF control, pressure control between the back side of the substrate W based on the heat transfer medium and the surface of the substrate support 20, temperature control of the cooler 107, and adsorption pressure control of the electrostatic chuck 106, the temperature of the substrate W can be raised or lowered, thereby enabling the execution of... Figure 3 Steps S4 and S5. Furthermore, the temperature of the substrate W can be raised or lowered using at least two of the following: control of LF, control of HF, control of the pressure between the back side of the substrate W and the surface of the substrate support 20 based on the heat transfer medium, control of the temperature of the cooler 107, and control of the adsorption pressure of the electrostatic chuck 106.

[0074] Specifically, Figure 4 This is an example of controlling the temperature of substrate W by controlling the high and low levels of LF power, or by controlling the on and off states. Figure 6 This is an example of changing the temperature of substrate W by controlling the high and low levels of HF and LF power, or by turning it on and off. Figure 7 (a) is an example of controlling the temperature of substrate W by controlling the high and low levels of HF power, LF power, and He pressure, or by controlling the on and off states. Figure 7 (b) is an example of controlling the temperature of the substrate W by means of high and low level control, or on and off control, of HF power, LF power, He pressure, and the adsorption pressure on the electrode 106a of the electrostatic chuck 106. Figure 4 , Figure 6 , Figure 7 In each specific example of (a), the temperature can be further changed by altering the control of the adsorption voltage on the electrode 106a of the electrostatic chuck 106.

[0075] exist Figure 4 as well as Figure 6 In this example, when a low-temperature temperature-regulating medium flows through the substrate support 20, the adsorption voltage is controlled to a high level when the LF is controlled to a low level, and vice versa. Thus, the substrate temperature can be efficiently lowered during period A, and the substrate temperature can be efficiently raised during period B. In other examples, the timing of controlling the adsorption voltage to a high or low level varies depending on the temperature of the temperature-regulating medium controlled by the chiller. In this example, the pressure of the heat transfer medium can be varied in accordance with the level of the adsorption voltage.

[0076] As described above, in Embodiment 6, in addition to the pulse control of LF, the heat conduction of the He gas supplied between the substrate support stage 20 and the substrate W is controlled. This promotes the cooling of the substrate during period A and the heating of the substrate during period B in each cycle, thereby promoting etching during period A and promoting the removal of reaction product 5 during period B. By repeating this process a predetermined number of times, the promotion of etching and the removal of reaction product are alternately performed. This further improves the removal efficiency of reaction product, effectively suppresses the generation of deep loading, and effectively promotes etching. Furthermore, the shape of the recess 4 can be improved to a desirable vertical shape.

[0077] It should be noted that in embodiment 6, pulse control of LF may be omitted, and only pulse control of the above-mentioned pressure based on He gas may be performed.

[0078] [Etching apparatus]

[0079] Reference Figure 8 An example of an etching apparatus 1 that can perform the etching methods of the various embodiments and examples described above will be described. Figure 8This is a cross-sectional schematic diagram illustrating an example of an etching apparatus 1 according to an embodiment. The etching apparatus 1 of the present invention includes a processing chamber 10, a gas supply source 15, a power supply 30, an exhaust device 65, and a control unit 100. Furthermore, the etching apparatus 1 includes a substrate support stage 20 and a gas inlet section. The gas inlet section is configured to introduce at least one processing gas into the processing chamber 10. The gas inlet section includes a nozzle 25. The substrate support stage 20 is disposed within the processing chamber 10. The nozzle 25 is disposed above the substrate support stage 20. In one embodiment, the nozzle 25 constitutes at least a portion of the ceiling of the processing chamber 10. An annular insulating member 40 is disposed around the outer periphery of the nozzle 25. The processing chamber 10 has the nozzle 25 and a plasma processing space 10s defined by the sidewall 10a of the processing chamber 10 and the substrate support stage 20. The processing chamber 10 has a gas supply port 45 for supplying at least one processing gas to the plasma processing space 10s, and a gas discharge port 60 for discharging gas from the plasma processing space 10s. The side wall 10a of the processing chamber 10 is grounded. The nozzle 25 and the substrate support 20 are electrically insulated from the housing of the processing chamber 10. A conveying port is provided on the side wall 10a, and the conveying port is opened and closed by a gate valve G to allow the substrate W to be moved into and out of the processing chamber 10.

[0080] The substrate support stage 20 includes a base 104 and an electrostatic chuck 106. Both the base 104 and the nozzle 25 include conductive components. The conductive components of the base 104 function as a lower electrode. The electrostatic chuck 106 is disposed on the base 104. The upper surface of the electrostatic chuck 106 has a substrate support surface. The electrostatic chuck 106 has a configuration in which conductive electrodes 106a are embedded within an insulating plate 106b.

[0081] The substrate support 20 may include a temperature control module configured to adjust at least one of the substrate support 20 and the substrate W to a target temperature. The temperature control module may include a heater, a temperature control medium, a flow path, or a combination thereof. In this invention, a flow path 104a is provided in the base 104, and a temperature control medium such as a refrigerant is controlled to the desired temperature by a chiller 107. The temperature control medium is supplied through the chiller 107, flowing in from the flow path inlet 104b, flowing out from the flow path outlet 104c through the flow path 104a, and then returning to the chiller 107. Additionally, a heat transfer medium such as He gas is supplied from the heat transfer gas supply source 85 to the area between the back surface of the substrate W and the surface of the substrate support 20 via a heat transfer gas line 130.

[0082] The nozzle 25 is configured to introduce at least one processing gas into the plasma processing space within 10 seconds from the gas supply source 15. The nozzle 25 has at least one gas supply port 45 and at least one gas diffusion chamber (in... Figure 8In this example, the gas diffusion chambers 50a and 50b are included, along with multiple gas inlets 55. The processing gas supplied to the gas supply port 45 is introduced into the plasma processing space 10s through the gas diffusion chambers 50a and 50b and via the multiple gas inlets 55. It should be noted that, in addition to the nozzle 25, the gas inlet may also include one or more side gas injectors (SGIs) installed in one or more openings formed in the sidewall 10a.

[0083] The gas supply source 15 has at least one gas source configured to supply at least one type of process gas from its respective gas source to the nozzle 25 via respective flow controllers. Each flow controller may include, for example, a mass flow controller or a pressure-controlled flow controller. Furthermore, the gas supply source 15 may include one or more flow modulation devices for modulating or pulsedizing the flow rate of the at least one type of process gas.

[0084] The power supply 30 includes an RF power supply connected to the processing chamber 10 via at least one matching unit (impedance matching circuit). The RF power supply is configured to supply at least one RF signal (RF power), such as a source RF signal and a bias RF signal, to conductive components of the substrate support stage 20 and / or the nozzle 25. As a result, plasma is formed from at least one processing gas supplied to the plasma processing space 10s. Therefore, the RF power supply can function as at least part of a plasma generation unit configured to generate plasma from one or more processing gases in the processing chamber 10. Furthermore, by supplying a bias RF signal to the conductive components of the substrate support stage 20, a bias potential is generated on the substrate W, thereby enabling the introduction of ionic components from the formed plasma into the substrate W.

[0085] In one embodiment, the RF power supply includes a high-frequency power supply 32 for supplying high-frequency power for plasma generation and a high-frequency power supply 34 for supplying high-frequency power for bias. The high-frequency power supply 32 is configured to be coupled to a conductive component of the substrate support stage 20 via a first matching unit 33, and to generate a source RF signal (source RF power) for plasma generation. In this invention, although the high-frequency power supply 32 is coupled to the conductive component of the substrate support stage 20, i.e., the base stage 104, it can also be coupled to a conductive component of the nozzle 25.

[0086] In one embodiment, the power supply 30 may have a first RF generation unit configured to generate multiple source RF signals with different frequencies. The generated one or more source RF signals are supplied to conductive components of the substrate support stage 20 and / or the nozzle 25. A high-frequency power supply 34 is configured to connect to the conductive components of the substrate support stage 20 via a second matching unit 35 and generate a bias RF signal (bias RF power). In one embodiment, the bias RF signal has a lower frequency than the source RF signal. In another embodiment, the power supply 30 may have a second RF generation unit configured to generate multiple bias RF signals with different frequencies. The generated one or more bias RF signals are supplied to the conductive components of the substrate support stage 20. Additionally, in various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0087] Additionally, a DC power supply may be present in conjunction with the processing chamber 10. The DC power supply may have a first DC generation unit configured to be connected to a conductive component of the substrate support 20 and to generate a first DC signal. The generated first DC signal is applied to the conductive component of the substrate support 20. In one embodiment, the first DC signal may be applied to other electrodes, such as electrode 106a within the electrostatic chuck 106. In one embodiment, a DC voltage is applied from the DC power supply 112 to electrode 106a within the electrostatic chuck 106, thereby attracting and holding the substrate W by the electrostatic chuck 106. In various embodiments, at least one of the first DC signals may be pulsed. It should be noted that the first DC generation unit may be provided based on an RF power supply, and the first DC generation unit may also replace the second RF generation unit described later.

[0088] The exhaust device 65 can be connected to a gas outlet 60, for example, located at the bottom of the processing chamber 10. The exhaust device 65 may include a pressure regulating valve and a vacuum pump. The pressure within the plasma processing space 10s is adjusted by the pressure regulating valve. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0089] The control unit 100 processes computer-executable commands that cause the etching apparatus 1 to perform the various processes described herein. The control unit 100 can be configured to control various elements of the etching apparatus 1 in a manner that executes the various processes of the various etching methods described herein. In one embodiment, part or all of the control unit 100 may be included in the etching apparatus 1. The control unit 100 may include, for example, a computer. The computer may include, for example, a processing unit (CPU) 105, a storage unit, and a communication interface. The processing unit 105 can be configured to perform various control actions based on programs stored in the storage unit. The storage unit includes RAM 115 (Random Access Memory) and ROM 110 (Read-Only Memory). The storage unit may include HDD (Hard Disk Drive), SSD (Solid State Drive), or a combination thereof. The communication interface can communicate with the etching apparatus 1 via a communication line such as a LAN (Local Area Network).

[0090] [other]

[0091] The etched film 3 can be a silicon-containing film. Examples of silicon-containing films include silicon oxide films, silicon nitride films, laminates of silicon oxide films and silicon nitride films, and laminates of silicon oxide films and polycrystalline silicon films. However, the etched film 3 is not limited to silicon-containing films, and can also be an organic film, a Low-K film, or other desired films.

[0092] The type of mask 2 is not limited as long as it can achieve a selection ratio with the etched film 3. For example, if the etched film 3 is a silicon oxide film, a silicon nitride film, a laminate of silicon oxide and silicon nitride films, or a laminate of silicon oxide and polycrystalline silicon films, a carbon-containing mask or a metal-containing mask can be used. If the etched film 3 is an organic film, a mask made of silicon oxide or the like can be used.

[0093] When the etched film 3 is a silicon-containing film, the etching gas can be a halogen-containing gas (e.g., fluorocarbon gas, hydrofluorocarbon gas, NF3 gas, SF6 gas, and combinations thereof). Furthermore, an inert gas such as Ar gas can be added as a rare gas to these gases.

[0094] [Postscript 1]

[0095] The above describes an etching method comprising (a) providing a substrate including an etched film on a substrate support stage disposed within a processing chamber, (b) setting the temperature of the substrate support stage, (c) generating plasma from the etching gas, (d) raising the temperature of the substrate, (e) lowering the temperature of the substrate, and (f) repeating steps (d) and (e) a predetermined number of times. Step (d) raising the temperature of the substrate can also be configured to remove reaction products generated by etching the etched film. Step (e) lowering the temperature of the substrate can also be configured to adsorb the etchant onto the etched film.

[0096] [Postscript 2]

[0097] In one embodiment, the direct current (DC) power supply associated with the processing chamber 10 may have a second DC generating unit configured to be connected to the conductive component constituting the nozzle 25 and to generate a second DC signal. The generated second DC signal is applied to the conductive component constituting the nozzle 25. In various embodiments, the second DC signal may be pulsed. It should be noted that the second DC generating unit may be configured to overlap with RF power from an RF power supply associated with the conductive component.

[0098] [Postscript 3]

[0099] In Embodiment 6, an example is given of controlling the pressure between the back side of the substrate W and the surface of the substrate support 20 by controlling the flow rate of a heat transfer medium such as He gas when the temperature regulating medium is controlled at a constant temperature (high or low) by the chiller 107. However, this is not a limitation. For example, the temperature of the substrate can be controlled by at least one of temperature control based on the temperature regulating medium of the chiller 107 and the pressure control based on the heat transfer medium. In the temperature control based on the chiller 107, temperature regulating media controlled at high and low temperatures can be prepared in two separate containers, and the flow rates of the high and low temperature regulating media supplied from the two containers can be adjusted to supply the temperature regulating medium at the desired temperature in the flow path 104a. Alternatively, in the temperature control based on the chiller 107, the temperature regulating medium can be stored in one container, and the temperature regulating medium in the container can be adjusted to the desired temperature while the temperature regulating medium is supplied in the flow path 104a. In embodiment 6, pulse control of LF can be performed or not; at least one of the above-mentioned pressure control based on the heat transfer medium and temperature control based on the temperature regulating medium of the chiller 107 can be performed.

[0100] [Postscript 4]

[0101] In one embodiment, the temperature of the substrate in process (e) can be above -120°C and below 40°C.

[0102] As described above, the etching method and etching apparatus according to the various embodiments and examples can suppress the generation of depth loading and promote etching. Furthermore, the shape of the recesses 4 in the etched film 3 can be improved. Additionally, when etching the etched film 3 in a pattern of a mask 2 with different diameters and widths, for example, the difference in etching rates between recesses 4 of different diameters and widths can be reduced.

[0103] It should be understood that all aspects of the etching methods and apparatus in the various embodiments and examples of this invention are illustrative and not limiting. The various embodiments and examples can be modified and improved in various ways within the scope of the appended claims and their spirit. The items described in the above-described embodiments and examples can also be configured in other ways without contradiction, and can also be combined without contradiction.

[0104] The etching apparatus of the present invention can be applied to any of the following types of apparatus: Capacitively Coupled Plasma (CCP), Inductively Coupled Plasma (ICP), Radial Line Slot Antenna (RLSA), Electron Cyclotron Resonance Plasma (ECR), and Helicon Wave Plasma (HWP).

Claims

1. An etching method, comprising: (a) A process of providing a substrate including an etched film on a substrate support stage disposed in a processing chamber and having an electrostatic chuck including electrodes. (b) The process of setting the temperature of the substrate support stage; (c) The process of generating plasma from self-etching gas; (d) A process of raising the temperature of the substrate to the temperature at which the reaction products generated by etching the substrate volatilize. (e) The process of lowering the temperature of the substrate to the temperature at which the etchant in the etching gas is adsorbed onto the substrate; and (f) A process that repeats the process in (d) and the process in (e) above a specified number of times. In steps (d) and (e) above, the temperature of the substrate is adjusted by controlling the switching of at least two of the following: the high-frequency power supplied to the substrate support stage for biasing, the flow rate of the heat transfer medium supplied between the substrate and the substrate support stage, and the adsorption voltage supplied to the electrode.

2. The etching method according to claim 1, wherein, The above-mentioned step (d) controls the supply of high-frequency power for biasing to be turned on. The process described in (e) above controls the supply of high-frequency power for biasing to be disconnected.

3. The etching method according to claim 1, wherein, The above-mentioned step (d) controls the supply of high-frequency power for biasing to a high level. In step (e) above, the supply of high-frequency power for bias is controlled to a low level, which is lower than the high level mentioned above.

4. The etching method according to any one of claims 1 to 3, wherein, It includes (i) the process of supplying the heat transfer medium between the substrate and the substrate support. When a temperature-regulating medium with a temperature lower than a preset threshold is output from a self-cooling unit and flows through the flow path formed in the substrate support, the process in step (d) controls the flow rate of the heat transfer medium in order to reduce the pressure between the substrate and the substrate support, and the process in step (e) controls the flow rate of the heat transfer medium in order to increase the pressure.

5. The etching method according to any one of claims 1 to 3, wherein, It includes (i) the process of supplying the heat transfer medium between the substrate and the substrate support. When a temperature-regulating medium with a temperature higher than a pre-set threshold is output from a self-cooling unit and flows in the flow path formed in the substrate support, the process in step (d) controls the flow rate of the heat transfer medium in order to increase the pressure between the substrate and the substrate support, and the process in step (e) controls the flow rate of the heat transfer medium in order to reduce the pressure.

6. The etching method according to any one of claims 1 to 3, wherein, The etching method includes a step of (j) supplying the adsorption voltage to the electrode. When a temperature-regulating medium with a temperature lower than a preset threshold is output and flows through the flow path formed on the substrate support, the adsorption voltage supplied to the electrode in process (d) is controlled to a low level, and the adsorption voltage supplied to the electrode in process (e) is controlled to a high level.

7. The etching method according to any one of claims 1 to 3, wherein, The etching method includes a step of (j) supplying the adsorption voltage to the electrode. When a self-cooling medium with a temperature higher than a pre-set threshold is output and flows in the flow path formed on the substrate support, the adsorption voltage supplied to the electrode in step (d) is controlled to a high level, and the adsorption voltage supplied to the electrode in step (e) is controlled to a low level.

8. The etching method according to claim 1, wherein, The temperature of the substrate in process (e) above is between -120°C and 40°C.

9. The etching method according to claim 8, wherein, The temperature of the substrate in process (e) above is between -40°C and 20°C.

10. The etching method according to any one of claims 1 to 3, wherein, The temperature difference between the substrate in process (d) and process (e) above is 10°C or more.

11. The etching method according to any one of claims 1 to 3, wherein, The frequency of one cycle of repeating the above (f) procedure is between 0.1 Hz and 100 kHz.

12. The etching method according to claim 11, wherein, This indicates that the duty cycle of the process described in (d) above is 10% to 70% of the time of one cycle.

13. The etching method according to claim 12, wherein, The duty cycle mentioned above is between 30% and 50%.

14. An etching apparatus for etching a film contained in a substrate, the etching apparatus comprising: a processing chamber; a substrate support stage disposed within the processing chamber; a plasma generation unit for generating plasma from etching gas; and a control unit. The aforementioned control unit is configured to perform the steps included in the etching method according to any one of claims 1 to 13.

Images