Etching apparatus and method

Abstract

To promote etching while preventing generation of depth loading.SOLUTION: There is provided a method for etching which includes the steps of: providing a substrate including an etching target film on a substrate supporting board arranged in a processing chamber (step a); setting a temperature of the substrate supporting board (step b); generating plasm from an etching gas (step c); raising the temperature of the substrate (step d); dropping the temperature of the substrate (step e); and repeating the step (d) and the step (e) a predetermined number of times.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to etching Device and etching method Regarding. [Background technology]

[0002] A method has been proposed for forming holes or the like in a silicon oxide film by etching in a low-temperature environment (see, for example, Patent Document 1). As the aspect ratio increases, the more likely it is that so-called depth loading, a phenomenon in which reaction products generated by etching accumulate at the bottom of holes and are difficult to volatilize, causing a decrease in the etching rate, occurs. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-22393 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique that can promote etching while suppressing the occurrence of depth loading. [Means for solving the problem]

[0005] According to one aspect of the present disclosure, there is provided an etching apparatus for etching a film to be etched included in a substrate, the apparatus having a processing chamber, a substrate support table disposed in the processing chamber, a plasma generating unit that generates plasma from an etching gas, and a control unit, the control unit controlling: (a) a step of providing the substrate including the film to be etched on the substrate support table disposed in the processing chamber; (b) a step of setting a temperature of the substrate support table; (c) a step of generating plasma from the etching gas; and (d) a step of controlling the temperature of the substrate. until a temperature at which reaction products produced by etching the substrate are volatilized. (e) increasing the temperature of the substrate. until the temperature at which the etchant of the etching gas is adsorbed on the substrate. and (f) repeating steps (d) and (e) a predetermined number of times. Effect of the Invention

[0006] According to one aspect, etching can be promoted while suppressing the occurrence of depth loading. [Brief description of the drawings]

[0007] [Figure 1] FIG. 4 is a diagram showing an example of an etching model according to the embodiment. [Diagram 2] 6 is a graph showing an example of an experimental result of the etching method according to the first and second embodiments. [Diagram 3] 10 is a flowchart showing an example of an etching method according to a third embodiment. [Figure 4] 11 is a time chart showing an example of an etching method according to embodiment 4. [Diagram 5] FIG. 5 is a diagram for explaining the etching method of FIG. 4. [Figure 6] 11 is a time chart showing an example of an etching method according to embodiment 5. [Figure 7] 13 is a time chart showing an example of an etching method according to embodiment 6. [Figure 8] FIG. 1 is a schematic cross-sectional view showing an example of an etching apparatus according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and duplicated descriptions may be omitted.

[0009] [Depth loading and etching] First, a decrease in etching rate due to depth loading will be described with reference to Fig. 1. Fig. 1 is a diagram showing an example of an etching model (structure) according to an embodiment. In the etching model according to the embodiment, a substrate W includes a film 3 to be etched and a mask 2. The film 3 to be etched is etched via a pattern formed on the mask 2, and as a result, a hole or a groove (hereinafter referred to as a recess 4) is formed in the film 3 to be etched.

[0010] When the aspect ratio (AR) of the recess 4 becomes about 20 or more as etching time passes, a phenomenon called depth loading occurs in which by-products generated by etching at the bottom of the recess 4 are difficult to discharge, and the etching rate decreases. The phenomenon of depth loading becomes prominent when the aspect ratio is 50 or more. Hereinafter, in this specification, an aspect ratio of 20 or more is referred to as a high aspect ratio, and an aspect ratio of less than 20 is referred to as a low aspect ratio. The pressure is higher at the bottom of a recess 4 with a high aspect ratio than at the bottom of a recess 4 with a low aspect ratio, and therefore the effect of depth loading is large.

[0011] For example, in a high aspect ratio contact (HARC), the deeper the recess 4, the more difficult it becomes to discharge the reaction product from the recess 4, causing depth loading and deteriorating throughput. Also, the shape of the bottom of the recess 4 deteriorates.

[0012] FIG. 1(a) shows a schematic diagram of etching when the temperature of the substrate is lower than room temperature. FIG. 1(b) shows a schematic diagram of etching when the temperature of the substrate is high (above room temperature). When the temperature of the substrate is lower than room temperature, the amount of etchant adsorbed to the substrate (the amount of reactive species generated) increases. In this case, the etching rate (E / R) is high in the low aspect ratio (low AR) region. In addition, since etching is accelerated, the amount of reaction product 5 generated during etching is large, but the discharge rate of reaction product 5 from recess 4 is slow. For this reason, as shown in the model (structure) of FIG. 1(a), it is difficult to discharge reaction product 5, and depth loading becomes evident in the high aspect ratio region. In addition, the shape of recess 4 may deteriorate, the bottom of recess 4 may become sharp, or the sidewall of recess 4 may not be vertical, causing twisting in the shape of recess 4. However, a bowing shape in which the sidewall of recess 4 spreads with respect to the opening of the etched film 3 is unlikely to occur.

[0013] When the temperature of the substrate increases, the reaction product 5 becomes more likely to volatilize, and as shown in the model of Fig. 1(b), the reaction product 5 is discharged from the recess 4, but the amount of etchant adsorbed to the bottom of the recess 4 decreases, and the etching rate does not increase. In addition, the bottom of the recess 4 becomes flat, and the sidewall of the recess 4 becomes nearly vertical. However, a bowing shape 6 is more likely to occur in the recess 4.

[0014] [Embodiment] From the above, the occurrence of depth loading, the level of the etching rate, and the shape of the recesses 4 are determined by the balance between the promotion of etching (the generation of reaction products 5) and the discharge of the reaction products 5 from the recesses 4. Therefore, in an etching method according to one embodiment, an etching technique is proposed that promotes etching while suppressing the occurrence of depth loading even in areas with a high aspect ratio, and suppresses tapering of the tips of the recesses 4 to make them vertical.

[0015] 2 is a graph showing an example of an experimental result of the etching method according to one embodiment. In this experiment, a substrate W including a film to be etched was placed on a substrate support 20 arranged in a processing chamber 10 and etched using an etching apparatus 1 (see FIG. 8) described later. During the experiment, an etching gas was supplied into the processing chamber 10 and the temperature of the substrate support 20 was controlled according to the following conditions to perform etching.

[0016] <Condition> Film to be etched: A laminated film consisting of alternating silicon oxide (SiOx) and silicon nitride (SiN) films Etching gas: halogen-containing gas, fluorocarbon gas Temperature of the substrate support: -40℃

[0017] In this experiment, the pressure inside the processing chamber was controlled to a relatively high pressure (27 mTorr: 3.6 Pa), and etching was performed under the above conditions. A curve e in FIG. 2 is shown as a reference example. In contrast to this, a curve f in FIG. 2 is shown as embodiment 1, and a curve b in FIG. 2 is shown as embodiment 1, and a curve c in FIG. 2 is shown as embodiment 2, and a curve g in FIG. 2 is shown as embodiment 2, and a curve b in FIG. 2 is shown as embodiment 2, and a curve c in FIG. 2 is shown as embodiment 2. Note that O2 gas was added to the etching gas to widen the opening of the recess 4, and O2 gas does not need to be added to dilute the etching gas.

[0018] 2, the horizontal axis indicates the process time (etching time), and the vertical axis indicates the Interval E / R. Interval E / R is expressed by the following formula and corresponds to the etching rate. Interval E / R=D n -D n-1 / (t n -t n-1 ) In the formula, n indicates the measurement point of the etching rate, t indicates the time, and D indicates the depth of the recess 4. For the measurement point n=1, the calculation was performed assuming that the time t was t0=0 (min) and the depth D was D0=0 (nm).

[0019] As a result, in the curve e of the reference example, the Interval E / R decreased rapidly as the process time progressed. This is thought to be because, in the early stage of the process, the temperature of the substrate support table 20 in FIG. 8 was low at -40°C, so the amount of etchant supplied was large, and the Interval E / R became high. In addition, the Interval E / R was high and the amount of reaction products generated increased, but as the process time progressed, the recess 4 became deeper, so the pressure inside the processing chamber 10 increased and it became difficult to discharge the reaction products from the recess 4. From the above, it is thought that as the process time became longer, depth loading occurred, and the decrease in Interval E / R (decrease in etching rate) became more noticeable.

[0020] In contrast, in the curve f of the first embodiment and the curve g of the second embodiment, the sharp decrease in Interval E / R as in the reference example did not occur, and the decrease in the etching rate with respect to the process time was gentle. That is, in the curve f of the first embodiment, the pressure in the processing chamber 10 was controlled to be lower than that in the reference example, so that the reaction product was easily discharged from the bottom of the recess 4, the occurrence of depth loading could be suppressed, and the decrease in the etching rate was gentle. In addition, in the curve g of the second embodiment, the etchant was diluted by the argon gas, and the amount of etchant supplied to the substrate was reduced compared to the reference example, and the amount of reaction product generated was reduced, so that the occurrence of depth loading could be suppressed, and the decrease in the etching rate was gentle.

[0021] In the reference example, Interval E / R decreases rapidly as the process time elapses. Then, for example, when etching the film 3 to be etched on the pattern of the mask 2 having different diameters and widths, the difference in the etching rate of the recesses 4 having different diameters and widths may become large. On the other hand, the low pressure in the etching method of the first embodiment and the dilution of the etching gas in the etching method of the second embodiment reduce the change in the etching rate of the recesses 4 having different diameters and widths. Therefore, according to the etching methods of the first and second embodiments, even when etching the film 3 to be etched on the pattern of the mask 2 having different diameters and widths, the difference in the etching rate of the recesses 4 having different diameters and widths can be reduced, and the decrease in the etching rate due to the process time can be made gentle.

[0022] However, in the etching methods of the first and second embodiments, the overall etching rate was lower than that of the reference example, and the etching rate tended to be low especially in the early stage of etching (low aspect ratio region). Therefore, the inventor has derived an etching method that does not lower the overall etching rate and does not cause a sudden decrease in the etching rate. FIG. 3 is a flow chart showing an example of an etching method according to the third embodiment. In this specification and drawings, among high frequency waves (RF: Radio Frequency), a high frequency wave that is supplied to the substrate support 20 or an electrode facing the substrate support 20 and has a frequency that mainly contributes to plasma generation is represented as HF. Also, a high frequency wave that is supplied to the substrate support 20 and has a frequency that mainly contributes to the attraction of ions in the plasma is represented as LF. The frequency of HF is higher than that of LF. HF and LF may each be supplied in a pulsed form. HF power is also referred to as source power, and LF power is also referred to as bias power.

[0023] As shown in FIG. 3, the etching method according to the third embodiment includes steps S1 to S6. First, in step S1, a substrate W including a film 3 to be etched is provided on a substrate support 20 disposed in a 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 a range of −40° C. to 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 may be set instead of setting the temperature of the substrate support 20. It is preferable to set the temperature of the substrate to a range of −40° C. to 20° C. Here, by supplying a heat transfer gas between the upper surface of the substrate support 20 and the rear surface of the substrate, the temperature of the substrate support 20 and the temperature of the substrate can be made substantially the same.

[0024] Next, in step S3, HF power (high frequency power for generating plasma) 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 increased, and the film 3 to be etched is etched using the generated plasma. Next, in step S5, the temperature of the substrate W is decreased, and the film 3 to be etched is etched using the generated plasma. Here, in step S4, bias power (LF in one example) is supplied to the substrate support table 20. In step S5, bias power (LF in one example) is not supplied to the substrate support table 20. Next, in step S6, it is determined whether the process of steps S4 and S5 has been repeated a predetermined number of times. The predetermined number of times is preset to an integer equal to or greater than 1. In step S6, the process of steps S4 and S5 is repeatedly executed until it is determined that the process has been repeated a predetermined number of times, and when it is determined that the process has been repeated a predetermined number of times, this process is terminated. Note that the order of the process of steps S4 and S5 may be reversed, and step S4 may be executed after step S5.

[0025] According to the etching method of the third embodiment, in S3, plasma is generated from the etching gas, and an etchant is supplied (adsorbed) from the generated plasma to the substrate surface, and etching proceeds. At the same time, a reaction product (etching by-product) is generated around the bottom of the recess 4.

[0026] Next, in S4, the temperature of the substrate W is raised to a preset 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 a temperature at which the reaction products volatilize. In step S5, the substrate temperature is lowered again and etching is performed. In step S5, since the etchant is more easily adsorbed at a lower substrate temperature, the substrate temperature is lowered to a temperature at which a sufficient amount of etchant is adsorbed to the substrate. In step S5, the substrate temperature may be set to -40°C or higher and 20°C or lower. The substrate temperature in step S4 is higher than the substrate temperature set in step S5. The difference between the substrate temperatures in steps S4 and S5 is preferably 10°C or higher. In step S4, the substrate temperature may be set to 10°C or higher and 30°C or lower.

[0027] [Embodiments 4 to 6] Next, three methods in embodiments 4 to 6 will be described as specific forms of embodiment 3, which are specific examples of embodiment 3, for the etching method performed by repeating steps S4 and S5 in the etching method shown in Fig. 3. Although embodiments 4 to 6 will be described by taking an example in which step S4 is executed after step S5 in Fig. 3, step S5 may be executed after step S4.

[0028] Examples of HF frequencies are 40 MHz, 60 MHz, 100 MHz, etc., and examples of LF frequencies are 400 kHz, 3 MHz, 13 MHz, etc., but are not limited to these. The bias voltage that mainly contributes to attracting ions is not limited to radio frequency (RF) and may be a DC voltage having a negative pulse frequency. In this case, the pulse frequency may be 100 kHz or more and 800 kHz or less, and may be 400 kHz as an example. The radio frequency power (RF power) may be set to 5 kW for HF power (high frequency power for plasma generation) and 10 kW for LF power (high frequency power for bias), and generally the power used increases as the aspect ratio increases.

[0029] <Embodiment 4> First, an example of an etching method according to embodiment 4, which is an example of embodiment 3, will be described with reference to Fig. 4 and Fig. 5. Fig. 4 is a time chart showing an example of the etching method according to embodiment 4. Fig. 5 is a diagram for explaining the etching method of Fig. 4.

[0030] In the etching method according to the fourth embodiment, HF is a continuous wave, and is supplied to the substrate support 20 or an electrode (shower head 25 in FIG. 8) facing the substrate support 20 during etching. Plasma is generated from the etching gas by the HF power, and the film to be etched 3 on the substrate W is etched by the plasma.

[0031] In the etching method according to the fourth embodiment, the LF is a pulse wave and is supplied to the substrate support 20 during etching, thereby controlling the temperature of the substrate. In the fourth embodiment, the LF is controlled to be off or low during the period A shown in FIG. 4, thereby executing step S5 in FIG. 3. For example, during the period A of the first cycle, the LF is controlled to be off or low, and the amount of ions in the plasma drawn into the substrate is reduced, so that the heat input from the plasma is reduced. As a result, the temperature of the substrate is lowered. This makes it possible to increase the adsorption (supply) of the etchant to the recess 4. In other words, since the etchant is more easily adsorbed at a lower substrate temperature, the substrate temperature is lowered to a temperature at which a sufficient amount of the etchant is adsorbed to the substrate, and etching is promoted.

[0032] Also, step S4 in FIG. 3 is executed by controlling the LF to be on or high during period B. During period B of the first cycle, the LF is controlled to be on or high, and the amount of ions in the plasma drawn into the substrate increases, increasing the heat input from the plasma. As a result, the temperature of the substrate rises. This makes it easier for the reaction product 5 to desorb. In other words, as shown in Step 2 in FIG. 5(b), raising the temperature of the substrate W to a preset temperature promotes the discharge (desorption) of the reaction product generated by etching. However, the supply of etchant is reduced.

[0033] Therefore, LF is again controlled to be off or low in the next second cycle period A. This again lowers the temperature of the substrate, increases the adsorption of the etchant to the recesses 4, and promotes etching.

[0034] In period B, the LF power is controlled so as to volatilize the reaction product 5 during etching and raise the temperature of the substrate to a temperature range where the reaction product can be removed from the recess 4. This promotes the discharge (desorption) of the reaction product. Note that since the substrate support table (mounting table) is maintained at a temperature of about -40°C in one example, the substrate temperatures set in periods A and B change with a certain time constant τ and saturate.

[0035] As described above, in the fourth embodiment, by alternately repeating the temperature drop of the substrate in period A and the temperature rise of the substrate in period B in each cycle, the adsorption of the etchant and etching are promoted in period A, and the discharge (desorption) of the reaction product 5 is promoted in period B. This is repeated a predetermined number of times, and the adsorption of the etchant and the promotion of etching are alternately performed with the discharge (desorption) of the reaction product, thereby eliminating the trade-off between the promotion of etching and the occurrence of depth loading. As a result, the etching method of the fourth embodiment can promote etching while suppressing the occurrence of depth loading. As a result, the throughput can be increased. In addition, bowing and twisting in the shape of the recess 4 can be suppressed, and the sidewall of the recess 4 can be formed substantially vertically.

[0036] The period of one cycle may be, for example, 0.01 milliseconds or more and 10 seconds or less (0.1 Hz or more and 100 kHz or less in frequency), 1 millisecond or more and 1 second or less (1 Hz or more and 1 kHz or less in frequency), or 10 milliseconds or more and 500 milliseconds or less (100 Hz or more and 2 Hz or less). The duty ratio (Duty) indicating the time for controlling the LF to be on or high relative to the time of one cycle, that is, the B period / (A period+B period), is preferably 10% or more and 70% or less, and more preferably 30% or more and 50% or less. The above HF frequency, LF frequency, period (frequency) of one cycle, duty ratio, etc. may be similarly applied to the fifth and sixth embodiments described later. In addition, regarding the relationship between "high" and "low" in this specification, "high" indicates a higher level (power level) than "low". In other words, if "high" is the first level and "low" is the second level, the first level is higher than the second level.

[0037] <Embodiment 5> Next, an example of an etching method according to embodiment 5, which is an example of embodiment 3, will be described with reference to Fig. 6. Fig. 6 is a time chart showing an example of the etching method according to embodiment 5. The etching method according to embodiment 5 differs from embodiment 4 in that HF ​​is pulse-controlled.

[0038] As in the fourth embodiment, the LF is pulse-controlled, and is controlled to be off or low in period A, and is controlled to be on or high in period B. In addition, in the fifth embodiment, the HF is controlled to be on or high in period A, and is controlled to be off or low in period B. The HF is supplied to the substrate support stand 20 or an electrode facing the substrate support stand 20.

[0039] According to this, in the A period, the LF is controlled to be off or low, and the amount of ions in the plasma drawn into the substrate is reduced, so that the heat input from the plasma is reduced. As a result, the temperature of the substrate is lowered. This can promote the adsorption (supply) of the etchant to the recess 4 and etching. Furthermore, in the A period, the HF is controlled to be on or high. As a result, the generation of the plasma is promoted in the A period, so that the amount of adsorption of the etchant increases, and etching is promoted. In contrast, in the B period, the LF is controlled to be on or high, so that the amount of ions in the plasma drawn into the substrate is increased, so that the heat input from the plasma is increased, and the temperature of the substrate is raised. This can promote the discharge (desorption) of the reaction products by etching. Furthermore, in the B period, the HF is controlled to be off or low. As a result, the amount of plasma generated is reduced, and the amount of etchant adsorbed into the recess 4 is reduced, so that the amount of reaction products generated is reduced.

[0040] As described above, in the fifth embodiment, the supply amount of etchant, the promotion of etching, and the discharge of reaction products are controlled by the pulse control of HF in addition to the pulse control of LF. That is, the increase in the supply amount of etchant and the promotion of etching by lowering the temperature of the substrate in period A, and the decrease in the supply amount of etchant and the discharge (desorption) of reaction products by raising the temperature of the substrate in period B are alternately repeated. This increases the discharge efficiency of the reaction products 5, and can promote etching while suppressing the occurrence of depth loading. In addition, the shape of the recess 4 can be further improved.

[0041] In the fourth and fifth embodiments, the LF waveform and / or the HF waveform are rectangular waves, but the present invention is not limited to this. The LF waveform and the HF waveform may be substantially rectangular waves including at least one of a rising slow-up and a falling slow-down, and the same applies to the sixth embodiment.

[0042] <Embodiment 6> Next, an example of an etching method according to the sixth embodiment, which is an example of the third embodiment, will be described with reference to FIG. 7. FIG. 7 is a time chart showing an example of the etching method according to the sixth embodiment. The etching method according to the sixth embodiment is different from the fifth embodiment in that the heat transfer medium supplied between the substrate support 20 and the substrate W is supplied by increasing and decreasing the pressure in a pulsed manner, as shown in FIGS. 7(a) and 7(b). Also, as shown in FIG. 7(b), the heat transfer medium supplied between the substrate support 20 and the substrate W and the adsorption voltage to the electrode 106a of the electrostatic chuck 106 in FIG. 8, which is provided on the substrate support 20, are supplied in a pulsed manner, as shown in FIG. 7(b). Note that the sixth embodiment is the same as the fifth embodiment in that the LF and HF are pulse-controlled, but the LF may be pulse-controlled and the HF may be a continuous wave, as in the fourth embodiment.

[0043] Supplying the heat transfer medium increases the efficiency of heat transfer between the substrate support table 20 and the substrate W. Therefore, the temperature of the substrate can be changed by changing the pressure between the substrate support table 20 and the substrate W through flow rate control of the heat transfer medium. Note that although He gas is used as the heat transfer medium in the sixth embodiment, other inert gases may also be used.

[0044] In the sixth embodiment, specifically, the LF is controlled to be off or low in the period A, and the LF is controlled to be on or high in the period B. In addition, the HF is controlled to be on or high in the period A, and the HF is controlled to be off or low in the period B.

[0045] In addition, in the sixth embodiment, the pressure between the back surface of the substrate W and the surface of the substrate support 20 (He BP: He Back Pressure) is controlled. As an example, a heat transfer medium such as He gas is supplied between the back surface of the substrate W and the surface of the substrate support 20 from the heat transfer gas supply source 85 through the heat transfer gas line 130, and the flow rate is controlled to high or low. In addition, a temperature control medium (temperature control fluid) is controlled to a desired temperature by the chiller 107 shown in FIG. 8. The temperature control medium is output from the chiller 107, flows into the flow path inlet 104b, passes through the flow path 104a, flows out from the flow path outlet 104c, and returns to the chiller 107. In the sixth embodiment, when the temperature control medium supplied by the chiller 107 is caused to flow through the flow path 104a, the flow rate of the He gas is changed to control the pressure between the back surface of the substrate W and the surface of the substrate support 20.

[0046] When the temperature of the temperature control medium controlled by the chiller 107 is higher than a preset threshold temperature, as shown in FIG. 7(a), the flow rate of He gas is controlled to low during the period A to lower the pressure between the back surface of the substrate W and the front surface of the substrate support 20. As a result, the heat transfer efficiency is lowered during the period A, and the temperature of the substrate support 20 heated by the temperature control medium flowing through the flow path of the substrate support 20 is made difficult to transfer to the substrate W, thereby lowering the temperature of the substrate W. This can promote the adsorption (supply) of the etchant to the recess 4 and etching. On the other hand, the flow rate of He gas is controlled to high during the period B to raise the pressure between the back surface of the substrate W and the front surface of the substrate support 20. As a result, the heat transfer efficiency is increased during the period B to make it easier to transfer the temperature of the substrate support 20 heated by the temperature control medium to the substrate W, thereby raising the temperature of the substrate. This can promote the exhaust (detachment) of the reaction product 5 from the recess 4.

[0047] When the temperature of the temperature control medium controlled by the chiller 107 is lower than a preset threshold temperature, as shown in FIG. 7(b), the flow rate of He gas is controlled to high during period A to increase the pressure between the rear surface of the substrate W and the front surface of the substrate support 20. This increases the heat transfer efficiency during period A, making it easier to transfer the temperature of the substrate support 20 cooled by the temperature control medium to the substrate W, thereby lowering the temperature of the substrate. This can promote adsorption of the etchant to the recess 4 and etching. On the other hand, during period B, the flow rate of He gas is controlled to low to reduce the pressure between the rear surface of the substrate W and the front surface of the substrate support 20. This reduces the heat transfer efficiency during period B, making it harder to transfer the temperature of the substrate support 20 to the substrate W, thereby raising the temperature of the substrate. This can promote the discharge of the reaction product 5 from the recess 4.

[0048] 8 may be controlled to be 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 can be changed, and the temperature of the substrate W can be adjusted. For example, increasing the adsorption voltage to the electrostatic chuck 106 improves the thermal conductivity, and decreasing the adsorption voltage decreases the thermal conductivity. This allows the temperature of the substrate W to be changed.

[0049] For example, in FIG. 7(b), the adsorption voltage is controlled to high in period A. This increases the heat transfer efficiency in period A, making it easier to transfer the temperature of the substrate support 20 cooled by the temperature control medium to the substrate W, thereby lowering the temperature of the substrate. This can promote adsorption of the etchant to the recess 4 and etching. In period B, the adsorption voltage is controlled to low. This decreases the heat transfer efficiency in period B, making it harder to transfer the temperature of the substrate support 20 cooled by the temperature control medium to the substrate W, thereby raising the temperature of the substrate. This can promote exhaust of the reaction product 5 from the recess 4. The period in which the adsorption voltage is controlled to high and the period in which it is controlled to low are switched depending on the controlled temperature of the temperature control medium. Although not shown, in FIG. 7(a), when the temperature of the substrate support 20 is heated by the temperature control medium, the adsorption voltage is controlled to low in period A and the adsorption voltage is controlled to high in period B.

[0050] 3 can be performed by raising and lowering the temperature of the substrate W using at least one of the above-described LF control, HF control, control of the pressure between the back surface of the substrate W and the front surface of the substrate support table 20 by the heat transfer medium, control of the temperature of the chiller 107, and control of the adsorption voltage of the electrostatic chuck 106. Furthermore, the temperature of the substrate W may be raised and lowered using at least two of the above-described LF control, HF control, control of the pressure between the back surface of the substrate W and the front surface of the substrate support table 20 by the heat transfer medium, control of the temperature of the chiller 107, and control of the adsorption voltage of the electrostatic chuck 106.

[0051] Specifically, FIG. 4 shows an example in which the temperature of the substrate W is controlled by high and low control or on and off control of the LF power. FIG. 6 shows an example in which the temperature of the substrate W is changed by high and low control or on and off control of the HF power and the LF power. FIG. 7(a) shows an example in which the temperature of the substrate W is controlled by high and low control or on and off control of the HF power, the LF power, and the pressure of He. FIG. 7(b) shows an example in which the temperature of the substrate W is controlled by high and low control or on and off control of the HF power, the LF power, the pressure of He, and the adsorption voltage to the electrode 106a of the electrostatic chuck 106. In each of the specific examples of FIG. 4, FIG. 6, and FIG. 7(a), the temperature can be changed by further controlling the adsorption voltage to the electrode 106a of the electrostatic chuck 106.

[0052] 4 and 6, as an example, when a low-temperature temperature control medium flows through the substrate support table 20, the adsorption voltage is controlled to high when the LF is controlled to low, and the adsorption voltage is controlled to low when the LF is controlled to high. This makes it possible to efficiently lower the substrate temperature in period A, and efficiently raise the substrate temperature in period B. In other examples as well, the timing for controlling the adsorption voltage to high or low differs depending on the temperature of the temperature control medium controlled by the chiller. In this example, the pressure of the heat transfer medium may be increased or decreased in accordance with the level of the adsorption voltage.

[0053] As described above, in the sixth embodiment, in addition to the pulse control of the LF, the thermal conduction of the He gas supplied between the substrate support table 20 and the substrate W is controlled. This promotes the temperature drop of the substrate in period A and the temperature rise of the substrate in period B in each cycle, thereby promoting etching in period A and promoting the discharge of the reaction products 5 in period B. By repeating this a predetermined number of times, the promotion of etching and the discharge of the reaction products are alternately performed. This further increases the discharge efficiency of the reaction products, effectively suppresses the occurrence of depth loading, and effectively promotes etching. In addition, the shape of the recess 4 can be improved to a good vertical shape.

[0054] In the sixth embodiment, the pulse control of the LF may not be performed, and only the pulse control of the pressure by the He gas may be performed.

[0055] [Etching equipment] An example of an etching apparatus 1 capable of carrying out the etching methods according to the above-described embodiments and examples will be described with reference to FIG. 8. FIG. 8 is a schematic cross-sectional view showing an example of the etching apparatus 1 according to the embodiment. The etching apparatus 1 of the present disclosure includes a processing chamber 10, a gas supply source 15, a power source 30, an exhaust device 65, and a control unit 100. The etching apparatus 1 also includes a substrate support 20 and a gas introduction unit. The gas introduction unit is configured to introduce at least one processing gas into the processing chamber 10. The gas introduction unit includes a shower head 25. The substrate support 20 is disposed in the processing chamber 10. The shower head 25 is disposed above the substrate support 20. In one embodiment, the shower head 25 constitutes at least a part of the ceiling of the processing chamber 10. A ring-shaped insulating member 40 is disposed on the outer periphery of the shower head 25. The processing chamber 10 has a plasma processing space 10s defined by the shower head 25, a sidewall 10a of the processing chamber 10, and the substrate support 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 exhaust port 60 for exhausting gas from the plasma processing space 10s. A sidewall 10a of the processing chamber 10 is grounded. The shower head 25 and the substrate support 20 are electrically insulated from the housing of the processing chamber 10. A transfer port is provided in the sidewall 10a, and the substrate W is loaded into and unloaded from the processing chamber 10 by opening and closing the transfer port with a gate valve G.

[0056] The substrate support 20 includes a base 104 and an electrostatic chuck 106. The base 104 and the shower head 25 include conductive members. The conductive member of the base 104 functions as a lower electrode. The electrostatic chuck 106 is disposed on the base 104. An upper surface of the electrostatic chuck 106 has a substrate support surface. The electrostatic chuck 106 has a configuration in which a conductive electrode 106a is embedded in an insulating plate 106b.

[0057] The substrate support 20 may include a temperature adjustment module configured to adjust at least one of the substrate support 20 and the substrate W to a target temperature. The temperature adjustment module may include a heater, a temperature adjustment medium, a flow path, or a combination thereof. In the present disclosure, a flow path 104a is provided in the base 104, and a temperature adjustment medium such as brine is controlled to a desired temperature by a chiller 107. The temperature adjustment medium is supplied by the chiller 107, flows in from a flow path inlet 104b, passes through the flow path 104a, flows out from a flow path outlet 104c, and returns to the chiller 107. In addition, a heat transfer medium such as He gas is supplied between the rear surface of the substrate W and the front surface of the substrate support 20 from a heat transfer gas supply source 85 through a heat transfer gas line 130.

[0058] The shower head 25 is configured to introduce at least one processing gas from the gas supply source 15 into the plasma processing space 10s. The shower head 25 has at least one gas supply port 45, at least one gas diffusion chamber (gas diffusion chambers 50a, 50b in the example of FIG. 8 ), and multiple gas inlets 55. The processing gas supplied to the gas supply port 45 passes through the gas diffusion chambers 50a, 50b and is introduced into the plasma processing space 10s from the multiple gas inlets 55. In addition to the shower head 25, the gas introduction unit may include one or more side gas injectors (SGI) attached to one or more openings formed in the side wall 10a.

[0059] The gas supply 15 includes at least one gas source and is configured to supply at least one process gas from a corresponding gas source through a corresponding flow controller to the showerhead 25. Each flow controller may include, for example, a mass flow controller or a pressure-controlled flow controller. Additionally, the gas supply 15 may include one or more flow modulation devices to modulate or pulse the flow rate of the at least one process gas.

[0060] The power supply 30 includes an RF power supply coupled to the process chamber 10 via at least one matcher (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 a conductive member of the substrate support 20 and / or a conductive member of the showerhead 25. This causes a plasma to be formed from at least one process gas supplied to the plasma processing space 10s. Thus, the RF power supply can function as at least a part of a plasma generating unit configured to generate a plasma from one or more process gases in the process chamber 10. In addition, by supplying a bias RF signal to the conductive member of the substrate support 20, a bias potential is generated on the substrate W, and ion components in the formed plasma can be attracted to the substrate W.

[0061] In one embodiment, the RF power supply includes a radio frequency power supply 32 that supplies radio frequency power for plasma generation and a radio frequency power supply 34 that supplies radio frequency power for bias. The radio frequency power supply 32 is coupled to a conductive member of the substrate support table 20 via a first matching device 33, and is configured to generate a source RF signal (source RF power) for plasma generation. In the present disclosure, the radio frequency power supply 32 is coupled to a base 104, which is a conductive member of the substrate support table 20, but may also be coupled to a conductive member of the showerhead 25.

[0062] In one embodiment, the power supply 30 may include a first RF generator configured to generate a plurality of source RF signals having different frequencies. The generated one or more source RF signals are provided to the conductive member of the substrate support 20 and / or the conductive member of the showerhead 25. The high frequency power supply 34 is coupled to the conductive member of the substrate support 20 via a second matching device 35 and configured to 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 one embodiment, the power supply 30 may include a second RF generator configured to generate a plurality of bias RF signals having different frequencies. The generated one or more bias RF signals are provided to the conductive member of the substrate support 20. In various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0063] There may also be a DC power supply coupled to the process chamber 10. The DC power supply may have a first DC generator connected to the conductive member of the substrate support 20 and configured to generate a first DC signal. The generated first DC signal is applied to the conductive member of the substrate support 20. In one embodiment, the first DC signal may be applied to another electrode, such as the electrode 106a in the electrostatic chuck 106. In one embodiment, a direct current voltage is applied from the DC power supply 112 to the electrode 106a in the electrostatic chuck 106, thereby attracting and holding the substrate W to the electrostatic chuck 106. In various embodiments, at least one of the first DC signals may be pulsed. It is noted that the first DC generator may be provided in addition to the RF power supply, or the first DC generator may be provided instead of the second RF generator described below.

[0064] The exhaust device 65 may be connected to a gas exhaust port 60 provided at the bottom of the processing chamber 10, for example. The exhaust device 65 may include a pressure regulating valve and a vacuum pump. The pressure in the plasma processing space 10s is adjusted by the pressure regulating valve. The vacuum pump may include a turbo molecular pump, a dry pump, or a combination thereof.

[0065] The control unit 100 processes computer-executable instructions that cause the etching apparatus 1 to perform various steps described in this disclosure. The control unit 100 may be configured to control each element of the etching apparatus 1 to perform each step of the various etching methods described herein. In one embodiment, a 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: Central Processing Unit) 105, a storage unit, and a communication interface. The processing unit 105 may be configured to perform various control operations based on a program stored in the storage unit. The storage unit includes a RAM 115 (Random Access Memory) and a ROM 110 (Read Only Memory). The storage unit may include a HDD (Hard Disk Drive), an SSD (Solid State Drive), or a combination thereof. The communication interface may communicate with the etching apparatus 1 via a communication line such as a LAN (Local Area Network).

[0066] [others] The film to be etched 3 may be a silicon-containing film. Examples of the silicon-containing film include a silicon oxide film, a silicon nitride film, a laminated film of a silicon oxide film and a silicon nitride film, and a laminated film of a silicon oxide film and a polysilicon film. However, the film to be etched 3 is not limited to a silicon-containing film, and may be an organic film, a low-k film, or any other desired film.

[0067] Any type of mask 2 can be used as long as it has a selectivity with respect to the film to be etched 3. For example, when the film to be etched 3 is a silicon oxide film, a silicon nitride film, a laminated film of a silicon oxide film and a silicon nitride film, or a laminated film of a silicon oxide film and a polysilicon film, a carbon-containing mask or a metal-containing mask may be used. When the film to be etched 3 is an organic film, a mask made of a silicon oxide film or the like may be used.

[0068] When the film 3 to be etched is a silicon-containing film, the etching gas may be a halogen-containing gas (e.g., fluorocarbon gas, hydrofluorocarbon gas, NF3 gas, SF6 gas, or a combination thereof). Furthermore, an inert gas such as Ar gas may be added to these gases as a rare gas.

[0069] [Appendix 1] The above describes an etching method including the steps of (a) providing a substrate including a film to be etched on a substrate support table disposed in a processing chamber, (b) setting the temperature of the substrate support table, (c) generating plasma from an etching gas, (d) increasing the temperature of the substrate, (e) decreasing the temperature of the substrate, and (f) repeating steps (d) and (e) a predetermined number of times. The step (d) of increasing the temperature of the substrate may be a step of removing a reaction product generated by etching the film to be etched. The step (e) of decreasing the temperature of the substrate may be a step of causing an etchant to be adsorbed on the film to be etched.

[0070] [Appendix 2] In one embodiment, a direct current (DC) power source coupled to the process chamber 10 may include a second DC generator connected to a conductive member that constitutes the showerhead 25 and configured to generate a second DC signal. The generated second DC signal is applied to the conductive member that constitutes the showerhead 25. In various embodiments, the second DC signal may be pulsed. Additionally, the second DC generator may be configured to apply the second DC signal in a superimposed manner on RF power from an RF power source coupled to the conductive member.

[0071] [Appendix 3] In the sixth embodiment, an example has been described in which the pressure between the rear surface of the substrate W and the front surface of the substrate support table 20 is controlled by controlling the flow rate of a heat transfer medium such as He gas while the chiller 107 controls the temperature control medium to a constant temperature (high or low), but the present invention is not limited thereto. For example, the temperature of the substrate may be controlled by at least one of the temperature control of the temperature control medium by the chiller 107 and the pressure control by the heat transfer medium. In the temperature control by the chiller 107, a temperature control medium controlled to a high temperature and a low temperature may be prepared in two tanks, respectively, and a temperature control medium at a desired temperature may be supplied to the flow path 104a by adjusting the flow rates of the high temperature and low temperature control medium supplied from the two tanks. In addition, in the temperature control by the chiller 107, the temperature control medium may be stored in one tank, and the temperature control medium in the tank may be supplied to the flow path 104a while adjusting the temperature control medium to a desired temperature. In the sixth embodiment, the pulse control of the LF may or may not be performed, and at least one of the pressure control by the heat transfer medium and the temperature control of the temperature adjustment medium by the chiller 107 may be performed.

[0072] [Appendix 4] In one embodiment, the temperature of the substrate in step (e) may be −120° C. or higher and 40° C. or lower.

[0073] As described above, according to the etching method and etching apparatus of each embodiment and each example, it is possible to promote etching while suppressing the occurrence of depth loading. In addition, it is possible to improve the shape of the recesses 4 in the film to be etched 3. In addition, for example, when etching the film to be etched 3 on a pattern of a mask 2 in which recesses 4 of different diameters and widths are mixed, it is possible to reduce the difference in etching rate between recesses 4 of different diameters and widths.

[0074] The etching method and the etching apparatus according to each embodiment and each example disclosed herein should be considered as illustrative and not restrictive in all respects. Each embodiment and each example can be modified and improved in various forms without departing from the scope and spirit of the appended claims. The matters described in the above embodiments and examples can be configured in other ways as long as they are not inconsistent, and can be combined as long as they are not inconsistent.

[0075] The etching apparatus of the present disclosure can be applied to any type of apparatus, including Capacitively Coupled Plasma (CCP), Inductively Coupled Plasma (ICP), Radial Line Slot Antenna (RLSA), Electron Cyclotron Resonance Plasma (ECR), and Helicon Wave Plasma (HWP). [Explanation of symbols]

[0076] 1 Etching equipment 2. Mask 3. Film to be etched 4 Recess 5. Reaction products 10 Processing chamber 10s Plasma treatment space 20 Substrate support stand 32 High frequency (HF) power supply 34 High frequency (LF) power supply 100 Control section W substrate

Claims

1. An etching apparatus for etching a film to be etched included in a substrate, the apparatus comprising: a processing chamber; a substrate support table disposed in the processing chamber; a plasma generating unit that generates plasma from an etching gas; and a control unit, the apparatus comprising: The control unit is (a) providing the substrate including the film to be etched on the substrate support disposed in the processing chamber; (b) setting a temperature of the substrate support table; (c) generating a plasma from the etching gas; (d) increasing the temperature of the substrate to a temperature at which reaction products produced by etching the substrate are volatilized; (e) decreasing the temperature of the substrate to a temperature at which an etchant of the etching gas is adsorbed onto the substrate; (f) repeating the steps (d) and (e) a predetermined number of times; An etching apparatus configured to perform a process including:

2. The step (d) includes controlling the supply of high frequency power for bias to be on (ON); The step (e) controls the supply of high frequency power for bias to be turned off.

2. The etching apparatus according to claim 1.

3. The step (d) includes controlling the supply of high frequency power for bias to high; The step (e) controls the supply of the bias high frequency power to a low level lower than the high level.

2. The etching apparatus according to claim 1.

4. The control unit is (i) providing a heat transfer medium between the substrate and the substrate support; When a temperature control medium output from a chiller and having a temperature lower than a preset threshold temperature flows through a flow path formed in the substrate support table, the step (d) controls the flow rate of the heat transfer medium to reduce the pressure between the substrate and the substrate support table, and the step (e) controls the flow rate of the heat transfer medium to increase the pressure. The etching apparatus according to any one of claims 1 to 3.

5. The control unit is (i) providing a heat transfer medium between the substrate and the substrate support; When a temperature control medium output from a chiller and having a temperature higher than a preset threshold temperature flows through a flow path formed in the substrate support table, the step (d) controls the flow rate of the heat transfer medium to increase the pressure between the substrate and the substrate support table, and the step (e) controls the flow rate of the heat transfer medium to decrease the pressure. The etching apparatus according to any one of claims 1 to 3.

6. The substrate support includes an electrostatic chuck including an electrode. The control unit is (j) providing an adsorption voltage to the electrode; when a temperature control medium output from a chiller and having a temperature lower than a preset threshold temperature flows through a flow path formed in the substrate support table, the step (d) controls an attraction voltage supplied to the electrode to be low, and the step (e) controls an attraction voltage supplied to the electrode to be high. The etching apparatus according to any one of claims 1 to 5.

7. The substrate support includes an electrostatic chuck including an electrode. The control unit is (j) providing an adsorption voltage to the electrode; when a temperature control medium output from a chiller and having a temperature higher than a preset threshold temperature flows through a flow path formed in the substrate support table, the step (d) controls an attraction voltage supplied to the electrode to be high, and the step (e) controls an attraction voltage supplied to the electrode to be low. The etching apparatus according to any one of claims 1 to 5.

8. The temperature of the substrate in the step (e) is −120° C. or higher and 40° C. or lower. The etching apparatus according to any one of claims 1 to 7.

9. The temperature of the substrate in the step (e) is −40° C. or higher and 20° C. or lower. The etching apparatus according to claim 8.

10. a difference in temperature of the substrate between the step (d) and the step (e) is 10° C. or more; The etching apparatus according to any one of claims 1 to 9.

11. The period of one cycle of repeating the step (f) is 0.1 Hz or more and 100 kHz or less. The etching apparatus according to any one of claims 1 to 10.

12. A duty ratio (Duty) indicating the time of the step (d) relative to the time of one cycle is 10% or more and 70% or less. The etching apparatus according to claim 11.

13. The duty ratio is 30% or more and 50% or less. The etching apparatus according to claim 12.

14. (a) providing a substrate including a film to be etched on a substrate support disposed in a processing chamber; (b) setting a temperature of the substrate support table; (c) generating a plasma from the etching gas; (d) increasing the temperature of the substrate to a temperature at which reaction products produced by etching the substrate are volatilized; (e) decreasing the temperature of the substrate to a temperature at which an etchant of the etching gas is adsorbed onto the substrate; (f) repeating the steps (d) and (e) a predetermined number of times; An etching method comprising:

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