TWI713109B - Etching method (1) - Google Patents

Abstract

The subject of the present invention is to etch the first area made of silicon oxide while suppressing the removal of the second area made of silicon nitride.

In the method of one embodiment, the first sequence is executed more than once in order to etch the first area, and then the second sequence is executed more than once. The first sequence of more than once and the second sequence of more than once include: the first process is to form a fluorine-containing carbon deposit on the processed body; and the second process is to use the fluorine contained in the deposit Carbon radicals etch the first area. The amount of individually etching the first area by the first sequence more than once is less than the amount of individually etching the first area by the second sequence more than once.

Description

Etching method (1)

The embodiment of the present invention relates to an etching method, in particular to a method of selectively etching a first area made of silicon oxide with respect to a second area made of silicon nitride by plasma treatment of a processed body的方法。 The method.

In the manufacture of electronic components, the area composed of silicon oxide (SiO ₂ ) is sometimes processed to form holes or trenches and other openings. In such a process, as described in the specification of US Pat. No. 7708859, the object to be processed is generally exposed to a plasma of fluorocarbon gas to make the area etched.

In addition, there is known a technique for selectively etching the first region made of silicon oxide with respect to the second region made of silicon nitride. An example of such a technology is SAC (Self-Alignd Contact) technology. The technical system of SAC is described in Japanese Patent Laid-Open No. 2000-307001.

The object to be processed as the processing target of the SAC technology has a first area made of silicon oxide, a second area made of silicon nitride, and a mask. The second area is provided to delimit the recess, the first area is provided to fill the recess and cover the second area, and the mask is provided on the first area to provide an opening in the recess. The conventional SAC technology uses a plasma containing a fluorocarbon gas, an oxygen gas, and a processing gas of a rare gas for etching the first area as described in Japanese Patent Application Laid-Open No. 2000-307001. By exposing the processed body to the plasma of the processing gas, the portion of the first region exposed from the opening of the mask is etched to form an upper opening. Furthermore, by exposing the body to be processed to the plasma of the processing gas, the portion surrounded by the second region, that is, the first region in the recess is self-matchingly etched. Thereby, the opening below the upper opening is formed in a self-matching manner.

Prior art literature

Patent Document 1 Specification of U.S. Patent No. 7708859

Patent Document 2 JP 2000-307001 A

In the above-mentioned prior art, when the first area is etched and the second area is exposed, a state occurs in a state where a film for protecting the second area is not formed on the surface of the second area. If the first area is etched in this state, the second area will be removed.

Therefore, a technology capable of etching the first area made of silicon oxide while suppressing the removal of the second area made of silicon nitride is required.

In one aspect, an etching method is provided, which selectively etches a first area made of silicon oxide with respect to a second area made of silicon nitride by plasma treatment of a processed body. The object to be processed has a second area that delimits the recess, a first area provided to fill the recess and cover the second area, and a mask provided on the first area. The mask is provided on the recess with An opening having a wider width than the width of the recess. This method includes: the first sequence more than once, which is performed to etch the first area; and the second sequence more than once, is to further etch the first area, and is performed after the first sequence is executed more than once. Implementer. The first sequence of more than one time and the second sequence of more than one time individually include: (a) The first process is to generate plasma containing fluorocarbon gas processing gas in the processing container containing the processed body, and then to be processed A fluorine-containing carbon deposit is formed on the body; and (b) the second process is to etch the first area by the fluorine-carbon radical contained in the deposit. In this method, the first sequence of more than one time is performed during the period including the exposure of the second area; the amount of the first area individually etched by the first sequence of more than one time is less than that of the second The amount of the first area etched individually in the sequence.

The first sequence and the second sequence of the above-mentioned aspect of the method are to form a fluorocarbon deposit on the surface of the object to be processed in the first process, and the fluorocarbon in the deposit is freed in the second process Base to etch the first area. On the other hand, although the fluorocarbon active species is deposited on the second area to protect the second area, when the first area is etched to expose the second area, the second area can be etched. Therefore, in this method, the first sequence is performed more than once during the period in which the second area is exposed. As a result, the amount of etching can be suppressed and deposits can be formed on the object to be processed, and the second area can be protected by the deposits. After that, the second sequence in which the amount of etching is large is performed more than once. Thus, according to this method, It is possible to etch the first area made of silicon oxide while suppressing the removal of the second area. In addition, the second sequence can be used to increase the etching rate of the first area.

In order to further etch the first region, the method of one embodiment further includes a third sequence performed more than once after the second sequence is performed more than once. The third sequence more than once includes the first process and the second process individually. The first sequence more than once, the second sequence more than once, and the third sequence more than once each include a plasma that generates inert gas (such as rare gas) in the second process, which supports the support of the object to be processed. The stage supplies high-frequency bias power to draw ions to the processed body. In this embodiment, the high-frequency bias power used in the second process included in the third sequence more than once is greater than the high-frequency bias used in the second process included in the second sequence more than once. Piezoelectricity. After the execution of the first sequence and the second sequence, the width of the opening of the mask, the width of the upper opening formed directly under the opening of the mask, and the width of the recess in the second area (ie, the lower opening) may be affected by Narrowing with sediment. This will happen due to the insufficient ion beam of the inert gas reaching the deep part of the lower opening. In order to cope with the shortage of ion beams, in this embodiment, the high-frequency bias power used in the second process of the third sequence is set to be higher than that used in the second process of the first and second sequences. Bias power comes with more power. According to the second process of the related third sequence, even if the lower opening is deep, ions can be supplied to the deep part of the lower opening.

In one embodiment, the first sequence more than once, the second sequence more than once, and the third sequence more than once individually further include the third process. The third process is to generate plasma of processing gas including oxygen-containing gas and inert gas in a processing container containing the object to be processed. According to this embodiment, the amount of deposits formed on the object to be treated can be appropriately reduced by the oxygen-active species. Thus, the opening of the mask and the opening formed by etching can be prevented from being blocked. In addition, in this embodiment, since the oxygen-containing gas in the processing gas is diluted by the inert gas, it is possible to suppress excessive removal of deposits.

In another aspect, there is provided an etching method that selectively etches a first area of the object to be processed made of silicon oxide with respect to a second area of the object to be processed made of silicon nitride. The initial state of the object to be processed before applying this method has: a second area that defines a recess, a first area set to fill the recess and cover the second area, and a mask set on the first area, The mask is provided on the recess with a wider width than the width of the recess. mouth. This method includes: (i) the first sequence more than once, which is performed to etch the first area; (ii) the second sequence more than once, is to further etch the first area and perform the first sequence more than once. Those executed after the sequence is executed; (iii) The process of etching the first area after more than one execution of the second sequence. The first sequence of more than one time and the second sequence of more than one time individually include: (a) The first process is to generate plasma containing fluorocarbon gas processing gas to form fluorocarbon deposits on the processed body; And (b) the second process is to etch the first area by the fluorocarbon radicals contained in the deposit. The ratio of the execution time of the second process included in the first sequence more than once to the execution time of the first process included in the first sequence more than once is greater than the execution time of the second process included in the second sequence more than once The ratio of the execution time of the first process contained in the second sequence for more than one time.

The first sequence and the second sequence of the above-mentioned other aspects of the method are to form a fluorocarbon deposit on the surface of the object to be processed in the first process, and use the fluorocarbon radical in the deposit in the second process To etch the first area. In each sequence, if the execution time of the second process becomes shorter than the execution time of the first process, the amount of deposits formed on the object to be processed increases and the amount of etching decreases. On the other hand, in each sequence, if the execution time of the second process becomes longer than the execution time of the first process, the amount of deposits formed on the object to be processed decreases and the amount of etching increases. Therefore, in the first sequence more than once, the amount of deposits formed on the object to be processed is relatively small, and the amount of etching is relatively large. Therefore, according to the first sequence more than once, the first area can be etched while suppressing the clogging of the opening formed in the object to be processed due to deposits. In addition, in the second sequence more than once, the amount of deposits formed on the object to be processed relatively increases, and the amount of etching relatively decreases. Therefore, according to the second sequence more than once, when the silicon oxide covering the upper surface of the second area is removed, the second area can be protected by deposits. In addition, in this method, the first area can be etched while protecting the second area by deposits formed by the second sequence more than once. Therefore, according to this method, it is possible to etch the first area made of silicon oxide while suppressing the removal of the second area made of silicon nitride. In addition, blocking of the opening formed by etching is suppressed.

In one embodiment, after the first sequence is performed more than once and before the second sequence is performed more than once, the method further includes: performing reactive ions on deposits formed on the object to be processed containing the material constituting the mask The etching process. According to this embodiment, by Perform the first sequence above to remove the deposits on the processed body caused by removing the mask. Thereby, deposits that may hinder the etching of the first region can be removed, and a good-shaped opening can be formed.

In the process of further etching the first region in one embodiment, the first region may be etched by reactive ion etching. For reactive ion etching, for example, a process gas containing fluorocarbon gas can be used. In this embodiment, the first area can be etched at a high etching rate while protecting the second area by deposits formed in the second sequence more than once.

In one embodiment, the first sequence that is more than once and the second sequence that is more than once may further include a third process to generate a plasma including an oxygen-containing gas and an inert gas processing gas to reduce fluorocarbon deposits. According to this embodiment, oxygen-active species can be used to appropriately reduce the amount of deposits formed at the treated body. Thus, the opening of the mask and the opening formed by etching can be prevented from being blocked. In addition, in this embodiment, since the oxygen-containing gas in the processing gas is diluted by the inert gas, it is possible to suppress excessive removal of deposits.

In one embodiment, the process of further etching the first area may include: performing a third sequence including the first process and the second process at least once. In this embodiment, the ratio of the execution time of the second process included in the third sequence more than once to the execution time of the first process included in the third sequence more than once is greater than that of the second process included in the second sequence more than once The ratio of the execution time to the execution time of the first process contained in the second sequence more than once. In this embodiment, the first area can be etched at a high etching rate while protecting the second area by deposits formed in the second sequence more than once.

In one embodiment, the first sequence more than once, the second sequence more than once, and the third sequence more than once may each further include a third process, which is to generate a plasma including an oxygen-containing gas and an inert gas processing gas, Reduce the deposit of fluorocarbon. According to this embodiment, oxygen-active species can moderately reduce the amount of deposits formed on the object to be treated. Thus, the opening of the mask and the opening formed by etching can be prevented from being blocked. In addition, in this embodiment, since the oxygen-containing gas in the processing gas is diluted by the inert gas, it is possible to suppress excessive removal of deposits.

As described above, it is possible to etch the first area made of silicon oxide while suppressing the removal of the second area made of silicon nitride.

10: Plasma processing device

12: Disposal of the container

30: Upper electrode

PD: Mounting table

LE: lower electrode

ESC: Electrostatic fixture

40: Gas source group

42: valve group

44: Flow Controller Group

50: Exhaust device

62: The first high frequency power supply

64: The second high frequency power supply

Cnt: Control Department

W: Wafer

R1: Zone 1

R2: Zone 2

OL: organic film

AL: Anti-reflective film

MK: Mask

DP: sediment

Fig. 1 shows a flowchart of an etching method according to an embodiment.

Fig. 2 is a cross-sectional view of an object to be processed that is an application object of the etching method according to an embodiment.

FIG. 3 is a diagram schematically showing an example of a plasma processing apparatus that can be used for the implementation of the method of the embodiment.

Fig. 4 is a cross-sectional view of the object to be processed in the middle stage of the implementation of the method shown in Fig. 1.

FIG. 5 is a cross-sectional view of the object to be processed in the middle stage of the implementation of the method shown in FIG. 1.

Fig. 6 is a cross-sectional view of the object to be processed in the middle stage of the implementation of the method shown in Fig. 1.

FIG. 7 is a cross-sectional view of the object to be processed in the middle stage of the implementation of the method shown in FIG. 1.

FIG. 8 is a cross-sectional view of the object to be processed in the middle stage of the implementation of the method shown in FIG. 1.

FIG. 9 is a cross-sectional view of the object to be processed in the middle stage of the implementation of the method shown in FIG. 1.

FIG. 10 is a cross-sectional view of the object to be processed in the middle stage of the implementation of the method shown in FIG. 1.

FIG. 11 is a cross-sectional view of the object to be processed in the middle stage of the implementation of the method shown in FIG. 1.

FIG. 12 is a cross-sectional view of the object to be processed in the middle stage of the implementation of the method shown in FIG. 1.

FIG. 13 is a cross-sectional view of the object to be processed in the middle stage of the implementation of the method shown in FIG. 1.

FIG. 14 is a cross-sectional view of the object to be processed in the middle stage of the implementation of the method shown in FIG. 1.

FIG. 15 is a cross-sectional view of the object to be processed in the middle stage of the implementation of the method shown in FIG. 1.

Fig. 16 is a cross-sectional view of the object to be processed in the middle stage of the implementation of the method shown in Fig. 1.

FIG. 17 is a flowchart showing the etching method of other embodiments.

Fig. 18 is a cross-sectional view illustrating the object to be processed to which the method shown in Fig. 17 is applied.

FIG. 19 is a cross-sectional view of the object to be processed in the middle stage of the implementation of the method shown in FIG. 17.

FIG. 20 is a cross-sectional view of the object to be processed in the middle stage of the implementation of the method shown in FIG. 17.

FIG. 21 is a cross-sectional view of the object to be processed in the middle stage of the implementation of the method shown in FIG. 17.

FIG. 22 is a cross-sectional view of the object to be processed in the middle stage of the implementation of the method shown in FIG. 17.

FIG. 23 is a cross-sectional view of the object to be processed in the middle stage of the implementation of the method shown in FIG. 17.

FIG. 24 is a cross-sectional view of the object to be processed in the middle stage of the implementation of the method shown in FIG. 17.

FIG. 25 is a cross-sectional view of the object to be processed in the middle of the implementation of the method shown in FIG. 17.

FIG. 26 is a cross-sectional view of the object to be processed in the middle stage of the implementation of the method shown in FIG. 17.

FIG. 27 is a cross-sectional view of the processed body after the method shown in FIG. 17 is implemented.

FIG. 28 is a flowchart showing a process that can be used as the process ST6 of FIG. 17.

Hereinafter, various embodiments will be described in detail with reference to the drawings. In addition, the same or corresponding parts in the drawings are given the same symbols.

Fig. 1 shows a flowchart of an etching method according to an embodiment. The method MT shown in FIG. 1 is a method of selectively etching the first region composed of silicon oxide with respect to the second region composed of silicon nitride by plasma treatment of the processed body.

FIG. 2 is a cross-sectional view of an object to be processed, which is an application object of the etching method according to an embodiment. As shown in FIG. 2, the object to be processed (that is, the wafer W) has a substrate SB, a first region R1, a second region R2, and an organic film OL forming a mask in the state before applying the method MT. In one example, the wafer W is obtained during the manufacturing of the fin-type electric field effect transistor, and further has a raised area RA, an anti-reflection film AL containing silicon, and a resist mask RM.

The raised area RA is provided so as to rise from the substrate SB. This raised area RA may constitute a gate area, for example. The second region R2 is made of silicon nitride (Si ₃ N ₄ ) and is provided on the surface of the raised region RA and the surface of the substrate SB. As shown in FIG. 2, this second region R2 extends so as to delimit recesses. In one example, the depth of the recess is about 150 nm, and the width of the recess is about 20 nm.

The first region R1 is made of silicon oxide (SiO ₂ ) and is provided on the second region R2. Specifically, the first region R1 is provided in such a manner as to fill in the recesses partitioned by the second region R2 and cover the second region R2.

The organic film OL is provided on the first region R1. The organic film OL may be composed of an organic material such as amorphous carbon. The anti-reflection film AL is provided on the organic film OL. The resist mask RM is disposed on the anti-reflection film AL. The opening provided by the resist mask RM has a wider width than the width of the recess on the recessed portion defined by the second region R2. The opening width of the resist mask RM is, for example, 60 nm. The pattern of the resist mask RM is formed by photolithography technology.

In the method MT, the processed object like the wafer W shown in FIG. 2 is processed in a plasma processing apparatus. FIG. 3 is a diagram schematically showing an example of a plasma processing apparatus that can be used for the implementation of the method of the embodiment. The plasma processing apparatus 10 shown in FIG. 3 is a capacitively coupled plasma etching apparatus, and includes a processing container 12 having a substantially cylindrical shape. The inner wall surface of the processing container 12 is made of, for example, anodized aluminum Constituted. This processing container 12 is safely grounded.

A substantially cylindrical support 14 is provided on the bottom of the processing container 12. The supporting portion 14 is made of, for example, an insulating material. The supporting portion 14 extends in the vertical direction from the bottom of the processing container 12 in the processing container 12. In addition, a mounting table PD is provided in the processing container 12. The mounting table PD is supported by the support part 14.

The mounting table PD holds the wafer W thereon. The mounting table PD has a lower electrode LE and an electrostatic clamp ESC. The lower electrode LE includes a first plate 18a and a second plate 18b. The first plate 18a and the second plate 18b are made of metal such as aluminum, and have a substantially disc shape. The second plate 18b is disposed on the first plate 18a and is electrically connected to the first plate 18a.

An electrostatic clamp ESC is provided on the second plate 18b. The electrostatic clamp ESC has a structure in which electrodes as conductive films are arranged between a pair of insulating layers or insulating sheets. The DC power supply 22 is electrically connected to the electrode of the electrostatic clamp ESC via the switch 23. The electrostatic clamp ESC uses electrostatic forces such as Coulomb force generated by the DC voltage from the DC power supply 22 to attract the wafer W. Thereby, the electrostatic clamp ESC can hold the wafer W.

A focus ring FR is arranged on the peripheral edge of the second plate 18b so as to surround the edge of the wafer W and the electrostatic clamp ESC. The focus ring FR is provided to improve etching uniformity. The focus ring FR is made of an appropriately selected material based on the film material to be etched, for example, it can be made of quartz.

A refrigerant flow path 24 is provided inside the second plate 18b. The refrigerant flow path 24 constitutes a temperature adjustment mechanism. The refrigerant flow path 24 is supplied with refrigerant from a condenser unit provided outside the processing container 12 via a pipe 26a. The refrigerant supplied to the refrigerant flow path 24 returns to the condenser unit via the pipe 26b. In this way, the refrigerant circulates between the refrigerant flow path 24 and the condenser unit. By controlling the temperature of the refrigerant, the temperature of the wafer W supported by the electrostatic clamp ESC is controlled.

In addition, a gas supply line 28 is provided in the plasma processing apparatus 10. The gas supply line 28 supplies heat transfer gas such as He gas from the heat transfer gas supply mechanism between the upper surface of the electrostatic chuck ESC and the inner surface of the wafer W.

In addition, the plasma processing apparatus 10 includes an upper electrode 30. The upper electrode 30 is arranged opposite to the mounting table PD above the mounting table PD. The lower electrode LE and the upper electrode 30 are arranged substantially parallel to each other. Provided between the upper electrode 30 and the lower electrode LE for the wafer W The processing space S for plasma processing.

The upper electrode 30 is supported on the upper portion of the processing container 12 via an insulating shielding member 32. In one embodiment, the upper electrode 30 is configured such that the distance in the vertical direction relative to the upper surface of the mounting table PD (that is, the wafer mounting surface) is variable. The upper electrode 30 may include an electrode plate 34 and an electrode support 36. The electrode plate 34 faces the processing space S, and the electrode plate 34 is provided with a plurality of gas ejection holes 34a. The electrode plate 34 is made of silicon in one embodiment.

The electrode support 36 detachably supports the electrode plate 34, and may be made of a conductive material such as aluminum. This electrode support 36 may have a water cooling structure. A gas diffusion chamber 36a is provided inside the electrode support 36. From the gas diffusion chamber 36a, a plurality of gas flow holes 36b connected to the gas ejection holes 34a extend downward. In addition, a gas introduction port 36 c for introducing processing gas into the gas diffusion chamber 36 a is formed in the electrode support 36, and the gas supply pipe 38 is connected to the gas introduction port 36 c.

The gas supply pipe 38 is connected to the gas source group 40 via the valve group 42 and the flow controller group 44. The gas source group 40 includes a plurality of gas sources. In one example, the gas source group 40 includes more than one fluorocarbon gas source, rare gas source, nitrogen gas (N ₂ gas) source, hydrogen gas (H ₂ gas) source, and oxygen-containing gas source. More than one fluorocarbon gas source may include a C ₄ F ₈ gas source, a CF ₄ gas source, and a C ₄ F ₆ gas source in one example. The rare gas source may be any rare gas source such as He gas, Ne gas, Ar gas, Kr gas, Xe gas, etc. In one example, it is an Ar gas source. In addition, the oxygen-containing gas source may be an oxygen gas (O ₂ gas) source in one example. In addition, the oxygen-containing gas may be any gas containing oxygen, for example, CO gas or carbon oxide gas such as CO ₂ gas.

The valve group 42 includes plural valves, and the flow controller group 44 includes plural flow controllers such as mass flow controllers. The plural gases of the gas source group 40 are respectively connected to the gas supply pipe 38 via corresponding valves of the valve group 42 and corresponding flow controllers of the flow controller group 44.

In addition, the plasma processing device 10 is provided with a deposition shield 46 along the inner wall of the processing container 12 in a detachable manner. The deposition shield 46 is also provided on the outer periphery of the support part 14. The deposition shield 46 prevents etching by-products (deposits) from adhering to the processing container 12, and may be formed by coating an aluminum material with ceramics such as Y ₂ O ₃ .

An exhaust plate 48 is provided on the bottom side of the processing container 12 and between the supporting portion 14 and the side wall of the processing container 12. The exhaust plate 48 may be formed by coating an aluminum material with ceramics such as Y ₂ O ₃ . In addition, a large number of through holes are formed in the exhaust plate 48. Below the exhaust plate 48 and in the processing container 12, an exhaust port 12e is provided. The exhaust port 12e is connected to an exhaust device 50 via an exhaust pipe 52. The exhaust device 50 has a vacuum pump such as a turbo-molecular pump, and can depressurize the space in the processing container 12 to a desired degree of vacuum. In addition, the side wall of the processing container 12 is provided with a carrying-out inlet 12g for the wafer W, and the carrying-out inlet 12g can be opened and closed by a gate valve 54.

In addition, the plasma processing apparatus 10 further includes a first high-frequency power supply 62 and a second high-frequency power supply 64. The first high-frequency power source 62 is a power source that generates high-frequency power for plasma generation, for example, generates high-frequency power with a frequency of 27 to 100 MHz. The first high-frequency power source 62 is connected to the upper electrode 30 via a matching device 66. The matching device 66 has a circuit for matching the output impedance of the first high-frequency power source 62 with the input impedance of the load side (the upper electrode 30 side). In addition, the first high-frequency power source 62 may be connected to the lower electrode LE via the matching device 66.

The second high-frequency power source 64 is a power source that generates high-frequency bias power for drawing ions to the wafer W, for example, generates high-frequency bias power with a frequency in the range of 400 kHz to 13.56 MHz. The second high-frequency power source 64 is connected to the lower electrode LE via a matching unit 68. The matching unit 68 has a circuit for matching the output impedance of the second high-frequency power source 64 with the input impedance of the load side (the lower electrode LE side).

In addition, the plasma processing device 10 is further provided with a power source 70. The power source 70 is connected to the upper electrode 30. The power supply 70 applies a voltage for drawing the positive ions existing in the processing space S to the electrode plate 34 to the upper electrode 30. In one example, the power source 70 is a DC power source that generates a negative DC voltage. In another example, the power source 70 may also be an AC power source that generates a relatively low frequency AC voltage. The voltage applied to the upper electrode from the power source 70 may be a voltage of -150V or less. That is, the voltage applied to the upper electrode 30 by the power supply 70 can be a negative voltage with an absolute value of 150V or more. If such a voltage is applied from the power source 70 to the upper electrode 30, the positive ions present in the processing space S collide with the electrode plate 34. Thereby, secondary electrons and/or silicon are released from the electrode plate 34. The released silicon will combine with the fluorine-active species present in the processing space S to reduce the amount of fluorine-active species.

In addition, in one embodiment, the plasma processing apparatus 10 may further include a control unit Cnt. The control unit Cnt is a computer equipped with a processor, a memory unit, an input device, a display device, etc., and controls each unit of the plasma processing device 10. The control unit Cnt can manage the plasma processing device 10 by inputting instructions by an operator using an input device, and can visually display the operating status of the plasma processing device 10 via a display device. Furthermore, it is stored in the memory part of the control part Cnt The processor is used to control various processing control programs executed in the plasma processing device 10, and processing programs (that is, processing recipes) are executed in various parts of the plasma processing device 10 according to processing conditions.

Hereinafter, referring to FIG. 1 again, the method MT will be described in detail. Refer to Figure 2, Figure 4 to Figure 16 as appropriate in the following description. Figures 4 to 16 are cross-sectional views of the processed object in the middle of the implementation of the method MT. In addition, the following description is directed to an example in which a plasma processing apparatus 10 shown in FIG. 3 is used to process the wafer W shown in FIG. 2 in the method MT.

First, in the method MT, the wafer W shown in FIG. 2 is carried into the plasma processing apparatus 10, the wafer W is placed on the mounting table PD, and is held by the mounting table PD.

In the method MT, the process ST1 is executed next. In the process ST1, the anti-reflective film AL is etched. Therefore, in the process ST1, the gas source selected from the plurality of gas sources of the gas source group 40 supplies the processing gas into the processing container 12. This processing gas contains fluorocarbon gas. The fluorocarbon gas may contain, for example, one or more of C ₄ F ₈ gas and CF ₄ gas. In addition, the processing gas may further contain rare gas (for example, Ar gas). In addition, in the process ST1, the exhaust device 50 is activated to set the pressure in the processing container 12 to a predetermined pressure. Furthermore, in the process ST1, the high-frequency power from the first high-frequency power source 62 is supplied to the upper electrode 30, and the high-frequency bias power from the second high-frequency power source 64 is supplied to the lower electrode LE.

The various conditions in the process ST1 are illustrated below.

‧Pressure inside the processing vessel: 10mTorr(1.33Pa)~50mTorr(6.65Pa)

‧Processing gas

C ₄ F ₈ gas: 10sccm~30sccm

CF ₄ gas: 150sccm~300sccm

Ar gas: 200sccm~500sccm

‧High frequency power for plasma generation: 300W~1000W

‧High frequency bias power: 200W~500W

In the process ST1, a plasma of processing gas is generated, and the anti-reflective film AL is etched by the fluorocarbon active species in the portion exposed from the opening of the resist mask RM. As a result, as shown in FIG. 4, the part exposed from the opening of the resist mask RM in the entire area of the anti-reflection film AL is removed. That is, the pattern of the resist mask RM is transferred to the anti-reflection film AL, and a pattern providing openings is formed on the anti-reflection film AL. In addition, the operations of the various parts of the plasma processing apparatus 10 in the process ST1 can be controlled by the control part Cnt control.

In the subsequent process ST2, the organic film OL is etched. Therefore, in the process ST2, the gas source selected from the plurality of gas sources of the gas source group 40 supplies the processing gas into the processing container 12. The processing gas may contain hydrogen gas and nitrogen gas. In addition, the processing gas used in the process ST2 may be other gases (for example, a processing gas containing an oxygen gas) as long as the organic film can be etched. In addition, in the process ST2, the exhaust device 50 operates to set the pressure in the processing container 12 to a predetermined pressure. Furthermore, in the process ST2, the high-frequency power from the first high-frequency power source 62 is supplied to the upper electrode 30, and the high-frequency bias power from the second high-frequency power source 64 is supplied to the lower electrode LE.

The various conditions in the process ST2 are illustrated below.

‧Pressure inside the processing vessel: 50mTorr(6.65Pa)~200mTorr(26.6Pa)

‧Processing gas

N ₂ gas: 200sccm~400sccm

H ₂ gas: 200sccm~400sccm

‧High frequency power for plasma generation: 500W~2000W

‧High frequency bias power: 200W~500W

In the process ST2, a plasma of processing gas is generated, and the organic film OL is etched in the portion exposed from the opening of the anti-reflective film AL. In addition, the resist mask RM is also etched. As a result, as shown in FIG. 5, the resist mask RM is removed, and the part exposed from the opening of the anti-reflection film AL among the entire area of the organic film OL is removed. That is, the pattern of the anti-reflection film AL is transferred to the organic film OL, a pattern providing openings MO is formed in the organic film OL, and the mask MK is generated from the organic film OL. In addition, the actions of the various parts of the plasma processing apparatus 10 in the process ST2 can be controlled by the control part Cnt.

In one embodiment, the process ST3 is performed after the process ST2 is performed. In the process ST3, the first region R1 is etched until the second region R2 is exposed. That is, the first region R1 is etched until a small amount of the first region R1 remains on the second region R2. Therefore, in the process ST3, the gas source selected from the plurality of gas sources of the gas source group 40 supplies the processing gas into the processing container 12. This processing gas contains fluorocarbon gas. In addition, the processing gas may further contain rare gas (for example, Ar gas). In addition, the processing gas may further include oxygen gas. In addition, in the process ST3, the exhaust device 50 is activated, and the pressure in the processing container 12 is set to a predetermined pressure. Furthermore, in the process ST3, the high-frequency power from the first high-frequency power source 62 is supplied to the upper electrode 30, from the second The high-frequency bias power of the high-frequency power supply 64 is supplied to the lower electrode LE.

In the process ST3, a plasma of the processing gas is generated, and the portion of the first region R1 exposed from the opening of the mask MK is etched by the active species of fluorocarbon. In addition, the etching in this process ST3 is reactive ion etching. The processing time of the process ST3 is set in such a way that the first region R1 remains on the second region R2 with a predetermined film thickness at the end of the process ST3. As a result of the execution of the process ST3, as shown in FIG. 6, the upper opening UO is partially formed. In addition, the operations of each part of the plasma processing apparatus 10 in the process ST3 can be controlled by the control part Cnt.

Here, in the process ST11 described later, the conditions are selected such that the formation of fluorocarbon deposits on the surface of the wafer W including the first region R1 is superior to the etching mode (ie, the deposition mode) of the first region R1. On the other hand, the process ST3 selects the condition that the etching of the first region R1 is better than the deposit forming mode (ie, the etching mode). Therefore, in one example, the fluorocarbon gas used in the process ST3 may contain more than one of C ₄ F ₈ gas and CF ₄ gas. The ratio of the number of fluorine atoms to the number of carbon atoms in the fluorocarbon gas used in the process ST11 (that is, the number of fluorine atoms/the number of carbon atoms) is the ratio of the number of fluorine atoms to the number of carbon atoms ( That is, a fluorocarbon gas with a high number of fluorine atoms/number of carbon atoms. In addition, in one example, in order to increase the degree of dissociation of the fluorocarbon gas, the high-frequency power used for plasma generation in process ST3 can be set to be greater than the high-frequency power used for plasma generation in process ST11 electricity. According to these examples, the etching mode can be realized. In addition, in one example, the high-frequency bias power used in the process ST3 can also be set to a larger power than the high-frequency bias power of the process ST11. According to this example, the energy of the drawn ions relative to the wafer W can be increased, and the first region R1 can be etched at a high speed.

The various conditions in the process ST3 are illustrated below.

‧Pressure inside the processing vessel: 10mTorr(1.33Pa)~50mTorr(6.65Pa)

‧Processing gas

C ₄ F ₈ gas: 10sccm~30sccm

CF ₄ gas: 50sccm~150sccm

Ar gas: 500sccm~1000sccm

O ₂ gas: 10sccm~30sccm

‧High frequency power for plasma generation: 500W~2000W

‧High frequency bias power: 500W~2000W

In one embodiment, secondly, the process ST4 is performed. In the process ST4, a plasma of a processing gas including an oxygen-containing gas is generated in the processing container 12. Therefore, in the process ST4, the gas source selected from the plurality of gas sources of the gas source group 40 supplies the processing gas into the processing container 12. In an example of this processing gas, oxygen gas may be contained as an oxygen-containing gas. In addition, the processing gas may further contain a rare gas (for example, Ar gas) or an inert gas such as nitrogen gas. In addition, in the process ST4, the exhaust device 50 is activated, and the pressure in the processing container 12 is set to a predetermined pressure. Furthermore, in the process ST4, the high-frequency power from the first high-frequency power source 62 is supplied to the upper electrode 30. In addition, in the process ST4, the high-frequency bias power from the second high-frequency power source 64 may not be supplied to the lower electrode LE.

Oxygen active species are generated in the process ST4, and the opening MO of the mask MK is expanded at the upper end portion by the oxygen active species. Specifically, as shown in FIG. 7, it is etched so that the upper shoulder portion of the mask MK that divides the upper end portion of the opening MO has a tapered shape. Thereby, even if the deposits generated in the subsequent process adhere to the surface of the opening MO of the partition mask MK, the reduction in the width of the opening MO can be reduced. In addition, the operations of the various parts of the plasma processing apparatus 10 in the process ST4 can be controlled by the control part Cnt.

Here, in the process ST12 described later, to reduce the trace deposits formed by each sequence, sometimes it is necessary to suppress excessive reduction of deposits. On the other hand, the process ST4 is performed to expand the width of the upper end portion of the opening MO of the mask MK, and the processing time is required to be short.

Below, various conditions in the process ST4 are illustrated.

‧Pressure inside the processing vessel: 30mTorr(3.99Pa)~200mTorr(26.6Pa)

‧Processing gas

O ₂ gas: 50sccm~500sccm

Ar gas: 200sccm~1500sccm

‧High frequency power for plasma generation: 100W~500W

‧High frequency bias power: 0W~200W

Through the above process, the wafer W in the state before the applicable sequence SQ1 is obtained. In the wafer W in this state, the first region R1 fills the recesses defined by the second region R2 to cover the second region R2. A mask MK is provided on the first region R1, and the mask MK is in the recess The upper system provides an opening with a wider width relative to the width of the recess. The method MT secondly executes the sequence SQ1 more than once for the wafer W in this state, and then executes the sequence SQ2 more than once. In addition, an implementation In the form, the sequence SQ3 can be executed more than once after the execution of the sequence SQ3 more than once. These sequences SQ1, SQ2, and SQ3 are implemented for etching the first region R1. Sequence SQ1, sequence SQ2, and sequence SQ3 include process ST11, process ST12, and process ST13, respectively. Hereinafter, the process ST11, the process ST12, and the process ST13 that are common to all of the sequence SQ1, the sequence SQ2, and the sequence SQ3 will be described in detail, and secondly, the difference between the sequence SQ1, the sequence SQ2, and the sequence SQ3 will be described.

In each sequence, first, the process ST11 is performed. In the process ST11, a plasma of processing gas is generated in the processing container 12 containing the wafer W. Therefore, in the process ST11, the gas source selected from the plurality of gas sources of the gas source group 40 supplies the processing gas into the processing container 12. This processing gas contains fluorocarbon gas. In addition, the processing gas may further include a rare gas (for example, Ar gas). In addition, in the process ST11, the exhaust device 50 is activated, and the pressure in the processing container 12 is set to a predetermined pressure. Furthermore, in the process ST11, the high-frequency power from the first high-frequency power supply 62 is supplied to the upper electrode 30.

In the process ST11, a plasma of processing gas containing fluorocarbon gas is generated, and the dissociated fluorocarbon is deposited on the surface of the wafer W to form a deposit DP (see FIG. 8, FIG. 11, and FIG. 14). The operations of the various parts of the plasma processing apparatus 10 in the related process ST11 are controlled by the control part Cnt.

As described above, in the process ST11, the conditions for the deposition mode are selected. Therefore, in one example, the fluorocarbon system uses C ₄ F ₆ gas.

Below, various conditions in the process ST11 are illustrated.

‧Pressure inside the processing vessel: 10mTorr(1.33Pa)~50mTorr(6.65Pa)

‧Processing gas

C ₄ F ₆ gas: 2sccm~10sccm

Ar gas: 500sccm~1500sccm

‧High frequency power for plasma generation: 100W~500W

‧High frequency bias power: 0W

In each sequence of the first embodiment, the process ST12 is executed next. In the process ST12, a plasma containing a processing gas containing oxygen gas and an inert gas is generated in the processing container 12. Therefore, in the process ST12, the gas source selected from the plurality of gas sources of the gas source group 40 supplies the processing gas into the processing container 12. In one example, the processing gas contains oxygen gas in terms of oxygen-containing gas. this In addition, in one example, the processing gas contains rare gases such as Ar gas in terms of inert gas. The inert gas may also be nitrogen gas. In addition, in the process ST12, the exhaust device 50 is activated, and the pressure in the processing container 12 is set to a predetermined pressure. Furthermore, in the process ST12, the high-frequency power from the first high-frequency power supply 62 is supplied to the upper electrode 30. In the process ST12, the high-frequency bias power from the second high-frequency power source 64 may not be supplied to the lower electrode LE.

In the process ST12, oxygen-active species are generated, and the amount of deposits DP on the wafer W will be moderately reduced due to the oxygen-active species (see FIG. 9, FIG. 12, and FIG. 15). As a result, it is possible to prevent the opening MO and the upper opening UO from being blocked by excessive deposits DP. In addition, in the processing gas used in the process ST12, the oxygen gas is diluted by the inert gas, which can prevent the deposit DP from being excessively removed. The operations of the various parts of the plasma processing apparatus 10 in the related process ST12 can be controlled by the control part Cnt.

Below, various conditions in the process ST12 are illustrated.

‧Pressure inside the processing vessel: 10mTorr(1.33Pa)~50mTorr(6.65Pa)

‧Processing gas

O ₂ gas: 2sccm~20sccm

Ar gas: 500sccm~1500sccm

‧High frequency power for plasma generation: 100W~500W

‧High frequency bias power: 0W

In one embodiment, each sequence of process ST12 (ie, one process ST12) is performed for more than 2 seconds, and the deposit DP in process ST12 can be etched at a rate of 1 nm/sec or less. In order to implement the above sequence using a plasma processing device like the plasma processing device 10, it takes time for gas switching to transfer between the processes of the process ST11, the process ST12, and the process ST13. Therefore, if the time required for stable discharge is considered, the process ST12 must be performed for more than 2 seconds. However, if the etching rate of the deposit DP is too high during such a time period, the deposit for protecting the second region R2 may be excessively removed. Therefore, in the process ST12, the deposit DP is etched at a rate below 1 nm/sec. Thereby, the amount of the deposit DP formed on the wafer W can be adjusted appropriately. In addition, the etching rate of the deposit DP in the process ST12 below 1nm/sec can be selected by selecting the pressure in the processing vessel, the degree of dilution of the oxygen in the processing gas by the rare gas (ie oxygen concentration) under the above-mentioned conditions, and Plasma generation is achieved with high-frequency power.

In each sequence, secondly, the process ST13 is executed. In the process ST13, the first region R1 is etched. Therefore, in the process ST13, the gas source selected from the plurality of gas sources of the gas source group 40 supplies the processing gas into the processing container 12. This treatment contains inert gas. The inert gas may be a rare gas such as Ar gas in one example. Alternatively, the inert gas may be nitrogen gas. In addition, in the process ST13, the exhaust device 50 is activated, and the pressure in the processing container 12 is set to a predetermined pressure. Furthermore, in the process ST13, the high-frequency power from the first high-frequency power source 62 is supplied to the upper electrode 30. In addition, in the process ST13, the high-frequency bias power from the second high-frequency power source 64 is supplied to the lower electrode LE.

Below, various conditions in the process ST13 are illustrated.

‧Pressure inside the processing vessel: 10mTorr(1.33Pa)~50mTorr(6.65Pa)

‧Processing gas

Ar gas: 500sccm~1500sccm

‧High frequency power for plasma generation: 100W~500W

‧High frequency bias power: 20W~300W

In the process ST13, a plasma of inert gas is generated, and ions are drawn to the wafer W. In addition, the first region R1 is etched by the fluorocarbon radicals contained in the deposit DP (see FIG. 10, FIG. 13 and FIG. 16). The operations of the various parts of the plasma processing apparatus 10 in the related process ST13 can be controlled by the control part Cnt.

In the method MT, the sequence SQ1 is executed during the period including the time when the second region R2 is exposed. In the process ST11 of the sequence SQ1, as shown in FIG. 8, a deposit DP is formed on the wafer W. In addition, FIG. 8 shows a state where the first region R1 is etched so that the second region R2 is exposed and a deposit DP is formed on the second region R2. This deposit DP protects the second area R2. In addition, in the process ST12 of the sequence SQ1, as shown in FIG. 9, the amount of the deposit DP formed in the process ST11 is reduced. In addition, in the process ST13 of the sequence SQ1, the first region R1 is etched by the fluorocarbon radicals contained in the deposit DP. According to this sequence SQ1, the second region R2 is exposed, and the first region R1 in the recess provided by the second region R2 is etched while the second region R2 is protected by the deposit DP. Thereby, as shown in FIG. 10, the lower opening LO is gradually formed.

The sequence SQ1 is repeated more than once. Therefore, as shown in FIG. 1, after the execution of the process ST13, the process STa determines whether the stop condition is satisfied. The stop condition is determined to satisfy the sequence SQ1 The situation where the set number of times has been implemented. In the process STa, when it is determined that the stop condition is not satisfied, the sequence SQ1 is executed from the process ST11. On the other hand, when it is determined that the stop condition is satisfied in the process STa, the sequence SQ2 is executed next.

In the process ST11 of the sequence SQ2, as shown in FIG. 11, a deposit DP is formed on the wafer W. In addition, in the process ST12 of the sequence SQ2, as shown in FIG. 12, the amount of the deposit DP formed in the process ST11 is reduced. Then, in the process ST13 of the sequence SQ2, the first region R1 is etched by the fluorocarbon radicals contained in the deposit DP. According to this sequence SQ2, the second region R2 is protected by the deposit DP so that the first region R1 in the recess provided by the second region R2 is further etched. Thereby, as shown in FIG. 13, the depth of the lower opening LO becomes deeper.

The sequence SQ2 is repeated more than once. Therefore, as shown in FIG. 1, after the execution of the process ST13, it is determined in the process STb whether the stop condition is satisfied. The stop condition is to determine that the sequence SQ2 has been executed a predetermined number of times. In the process STb, when it is determined that the stop condition is not satisfied, the sequence SQ2 is executed from the process ST11. On the other hand, when it is determined that the stop condition is satisfied in the process STb, secondly, the execution of the sequence SQ2 is ended.

In the method MT, the processing conditions of the sequence SQ1 are set in such a way that the etching amount of the first region R1 in each sequence SQ1 is smaller than the etching amount of the first region R1 in each sequence SQ2. In one example, the execution time length of each sequence SQ1 is set to be shorter than the execution time length of each sequence SQ2. In this example, the ratio of the execution time length of the process ST11, the execution time length of the process ST12, and the execution time length of the process ST13 in the sequence SQ1 can be set to the execution time length of the process ST11 and the execution time length of the process ST12 in the sequence SQ2 , And the ratio of the execution time length of the process ST13 is the same. For example, in sequence SQ1, the execution time length of process ST11 is selected from the range of 2 seconds to 5 seconds, and the execution time length of process ST12 is selected from the range of 2 seconds to 5 seconds. Process ST13 The length of the execution time is selected from the range of 5 seconds to 10 seconds. In addition, in sequence SQ2, the execution time of process ST11 is selected from the range of 2 seconds to 10 seconds, and the execution time of process ST12 is selected from the range of 2 seconds to 10 seconds. Process ST13 The length of the execution time is selected from the range of 5 seconds to 20 seconds.

The fluorocarbon active species generated by the process ST11 will be deposited on the second region R2 to protect the second In the region R2, when the first region R1 is etched to expose the second region R2, the second region R2 can be etched. Therefore, in the method MT, the sequence SQ1 is executed more than once during the period in which the second region R2 is exposed. Thereby, the deposit DP can be formed on the wafer W while suppressing the etching amount, and the second region R2 can be protected by the deposit DP. After that, the sequence SQ2 with a large amount of etching is executed more than once. Therefore, according to the method MT, it is possible to etch the first region R1 while suppressing the removal of the second region R2.

In addition, since the deposit DP has been formed on the second region R2 in the sequence SQ1, even if the etching amount in each sequence SQ2 is increased, the removal of the second region R2 can be suppressed. In this way, the etching amount of each sequence SQ2 is increased compared with the etching amount of each sequence SQ1, which can increase the etching rate of the first region R1 in the method MT.

In the method MT of an embodiment, the sequence SQ3 is executed after the execution of the sequence SQ2. In the process ST11 of the sequence SQ3, as shown in FIG. 14, a deposit DP is formed on the wafer W. Then, in the process ST12 of the sequence SQ3, as shown in FIG. 15, the amount of the deposit DP formed in the process ST11 is reduced. Then, in the process ST13 of sequence SQ3, the first region R1 is etched by the fluorocarbon radicals contained in the deposit DP. According to this sequence SQ3, when the second region R2 is protected by the deposit DP, the first region R1 in the recess provided by the second region R2 is further etched. Thereby, as shown in FIG. 16, the depth of the lower opening LO becomes deeper, and finally the first region R1 is etched until the second region R2 located at the bottom of the recess is exposed.

The sequence SQ3 is repeated more than once. Therefore, as shown in FIG. 1, after the execution of the process ST13, it is determined in the process STc whether the stop condition is satisfied. The stop condition is to determine that the sequence SQ3 has been executed a predetermined number of times. In the process STc, when it is determined that the stop condition is not satisfied, the sequence SQ3 is executed from the process ST11. On the other hand, when it is determined that the stop condition is satisfied in the process STc, the implementation of the method MT is ended.

In the process ST13 of the sequence SQ3, the high-frequency bias power is set to be larger than the high-frequency bias power used in the process ST13 of the sequences SQ1 and SQ2. For example, in the process ST13 of the sequence SQ1 and the sequence SQ2, the high-frequency bias power is set at a power of 20W-100W, and in the process ST13 of the sequence SQ3, the high-frequency bias power is set at a power of 100W~300W. In addition, in an example of sequence SQ3, the execution time of process ST11 is selected from the range of 2 seconds to 10 seconds, and the execution time of process ST12 is selected from the range of 2 seconds to 10 seconds. The length of time is selected. The length of the execution time of process ST13 is selected from the range of 5 seconds to 15 seconds.

As shown in FIG. 14, after the sequence SQ1 and the sequence SQ2 are executed, the amount of the deposit DP on the wafer W becomes quite large. If the amount of the deposit DP increases, the width of the opening MO, the width of the upper opening UO, and the width of the lower opening LO will be narrowed by the deposit DP. In this case, it may happen that the flow of ions reaching the deep part of the lower opening LO is insufficient. However, the process ST13 of the sequence SQ3 utilizes relatively large high-frequency bias power to increase the energy of the ions drawn to the wafer W. As a result, even if the lower opening LO is deep, ions can be supplied to the deep part of the lower opening LO.

Hereinafter, the etching method of other embodiments will be described. FIG. 17 is a flowchart showing the etching method of other embodiments. The method MT2 shown in FIG. 17 is to process the first region of the processed body composed of silicon oxide with respect to the second region of the processed body composed of silicon nitride by plasma treatment of the processed body. Method of selective etching. This method MT2 includes the sequence SQ21 more than once, the sequence SQ22 more than once, and the process ST6. The method MT2 and the method MT can also include the process ST3. In addition, the method MT2 may further include the process ST5.

FIG. 18 is a cross-sectional view illustrating the object of application of the method MT2 shown in FIG. 17, which is the processed body. As shown in FIG. 18, the object to be processed (hereinafter referred to as "wafer W2") has a substrate SB, a first region R1, and a second region in the same initial state before applying the method MT2 as the above-mentioned wafer W. R2. In addition, the wafer W2 may further have a raised area RA similarly to the above-mentioned wafer W. Furthermore, the wafer W2 may further have a mask MK2 on the first region R1. The mask MK2 is to provide an opening MO2 having a wider width than the width of the concave portion on the concave portion defined by the second region R2.

The mask MK2 can be made of any material selected in such a way that the first region R1 is selectively etched with respect to the mask MK2. For example, the mask MK2 may also be formed of an organic film like the mask MK of the wafer W. When the mask MK2 is formed of an organic film, the object to be processed to which the method MT2 is applied can also have a resist mask RM, an anti-reflection film AL, and an organic film OL as in the wafer W shown in FIG. 2. In addition, in order to form the mask MK2 from the organic film OL, the method MT2 may further include the process ST1, the process ST2, and the process ST4 like the method MT.

Or, the mask MK2 may also be a mask containing metal. For example, the mask MK2 can be made of TiN And other materials. In this case, another mask can be prepared on the metal layer, and the pattern of the other mask is transferred to the metal layer by plasma etching, thereby forming the mask MK2 from the metal layer.

Hereinafter, referring to FIG. 17 again, the method MT2 will be described in detail. In the following description, in addition to FIG. 17, refer to FIG. 18 and FIGS. 19 to 27. 19 to 26 are cross-sectional views of the processed body in the mid-stage of the implementation of the method shown in FIG. 17, and FIG. 27 is a cross-sectional view of the processed body after the implementation of the method shown in FIG. 17. In addition, FIG. 28 can be used as a processing flowchart for the process ST6 of FIG. 17. In addition, in the following description, the method MT2 refers to an example of using a plasma processing apparatus 10 shown in FIG. 3 to process the wafer W shown in FIG. 18. When each process described below is executed, each part of the plasma processing apparatus 10 is controlled by the control part Cnt.

In the method MT2, the wafer W2 shown in FIG. 18 is placed on the placement table PD and held on the placement table PD. In the method MT2, the process ST3 is executed next. The process ST3 of the method MT2 and the process ST3 of the method MT are the same process, which is a process of etching the first region R1 by reactive ion etching. Through the process ST3, the portion of the first region R1 exposed from the opening of the mask MK is etched by the fluorocarbon active species. The processing time of this process ST3 is set in such a way that the first region R1 remains on the second region R2 with a predetermined film thickness when the process ST3 ends. As a result of the execution of the process ST3, as shown in FIG. 19, the upper opening UO2 is partially formed.

Next, in the method MT2, the sequence SQ21 is executed more than once in order to etch the first region R1. The sequence SQ21 that is more than once includes the process ST21 and the process ST23 respectively. The individual sequence SQ21 that is more than one time may further include the process ST22.

The process ST21 and process ST11 in the individual sequence SQ21 that are more than one time are the same process. In the individual process ST21 of the sequence SQ21 that is performed more than once, a plasma of processing gas containing fluorocarbon gas is generated. Then, the dissociated fluorocarbon is deposited on the surface of the wafer W to form a deposit DP as shown in FIG. 20.

Hereinafter, various conditions in the individual process ST21 of the sequence SQ21 that are more than once are illustrated.

‧Pressure inside the processing vessel: 10mTorr(1.33Pa)~50mTorr(6.65Pa)

‧Processing gas

C ₄ F ₆ gas: 3sccm~5sccm

Ar gas: 700sccm~1200sccm

‧High frequency power for plasma generation: 100W~500W

‧High frequency bias power: 0W

‧Processing time: 0.5 seconds

In the individual sequence SQ21 that is more than one time, the second is to implement the process ST22. The individual process ST22 of the sequence SQ21 that is more than once is the same process as the process ST12. In the individual process ST22 of the sequence SQ21 that is performed more than once, oxygen-active species are generated, and the amount of deposits DP on the wafer W2 is moderately reduced by the oxygen-active species as shown in FIG. 21. As a result, it is possible to prevent the opening MO2 and the upper opening UO2 from being blocked by the excess deposit DP. In addition, in the processing gas used in the individual process ST22 of the sequence SQ21 for more than one time, since the oxygen gas is diluted by the inert gas, the deposits DP can be prevented from being excessively removed.

Hereinafter, various conditions in the individual process ST22 of the sequence SQ21 that are more than once are illustrated.

‧Pressure inside the processing vessel: 10mTorr(1.33Pa)~50mTorr(6.65Pa)

‧Processing gas

O ₂ gas: 4sccm~6sccm

Ar gas: 700sccm~1200sccm

‧High frequency power for plasma generation: 100W~500W

‧High frequency bias power: 0W

‧Processing time: 1 second

In the individual sequence SQ21 that is more than one time, the second is to implement the process ST23. The individual process ST23 and process ST13 of the sequence SQ21 that are more than once are the same process. In the individual process ST23 of the sequence SQ21 that is performed more than once, an inert gas plasma is generated, and the ions are drawn to the wafer W2. Then, due to the fluorocarbon radicals contained in the deposit DP, as shown in FIG. 22, the first region R1 is etched. Thereby, the upper opening UO2 is formed.

Hereinafter, various conditions in the individual process ST23 of the sequence SQ21 that are more than once are illustrated.

‧Pressure inside the processing vessel: 10mTorr(1.33Pa)~50mTorr(6.65Pa)

‧Processing gas

Ar gas: 700sccm~1200sccm

‧High frequency power for plasma generation: 100W~500W

‧High frequency bias power: 0W~20W

In addition, in the individual sequence SQ21 that is more than one time, the execution time of the process ST23 affects the process The ratio of the execution time of ST21 is set to be greater than the ratio of the execution time of the process ST23 individually included in the sequence SQ22 described later to the execution time of the process ST21. For example, the execution time of the individual process ST21 of the sequence SQ21 more than once and the execution time of the individual process ST21 of the sequence SQ22 more than once can be set to the same time length, and the execution time of the individual process ST23 of the sequence SQ21 more than once can also be set It is longer than the execution time of the individual process ST23 of the sequence SQ22 which is more than one time. For example, the execution time of the individual process ST23 of the sequence SQ21 more than once can be set to 7 seconds, and the execution time of the individual process ST23 of the sequence SQ22 more than once can be set to 5 seconds.

In each sequence, if the execution time of the process ST23 is shorter than the execution time of the process ST21, the amount of the deposit DP formed on the wafer W2 will increase, and the etching amount will decrease. On the other hand, in each sequence, if the execution time of the process ST23 becomes longer relative to the execution time of the process ST21, the amount of the deposit DP formed on the wafer W2 decreases and the etching amount increases. Therefore, in the individual sequence SQ21 that is performed more than once, the amount of the deposit DP formed on the wafer W2 is relatively small, and the etching amount is relatively large. Therefore, according to the sequence SQ21 more than once, the first region R1 can be etched while suppressing the clogging of the opening formed in the wafer W2 due to the deposit DP.

In method MT2, in the subsequent process STJ1, it is determined whether the stopping conditions are met. The stop condition is to determine that the sequence SQ21 has been executed a predetermined number of times. In the process STJ1, when it is determined that the stop condition is not met, the sequence SQ21 is executed from the process ST21. On the other hand, in the process STJ1, when it is determined that the stop condition is satisfied, the execution of the sequence SQ21 is completed more than once.

As described above, in the sequence SQ21 that is performed more than once, the amount of the formed deposit DP is relatively small, and the etching amount is relatively large. As a result, not only the first region R1 but also the mask MK2 is removed. As shown in FIG. 22, the deposit DP2 including the material constituting the mask MK2 can be formed on the wafer W2. In order to remove the deposit DP2, in the method MT2, secondly, the process ST5 is performed. In the process ST5, reactive ion etching is performed on the wafer W2 shown in FIG. 22.

In the process ST5, a gas source selected from a plurality of gas sources in the gas source group 40 supplies the processing gas into the processing container 12. The processing gas system is appropriately selected according to the material constituting the deposit DP2. In one example, the processing gas includes fluorocarbon gas. In addition, the processing gas may further include a rare gas (for example, Ar gas). In addition, the processing gas may further include oxygen gas. In addition, In the process ST5, the exhaust device 50 is activated, and the pressure in the processing container 12 is set to a predetermined pressure. Furthermore, in the process ST5, the high-frequency power from the first high-frequency power source 62 is supplied to the upper electrode 30, and the high-frequency bias power from the second high-frequency power source 64 is supplied to the lower electrode LE. In this process ST5, a plasma of processing gas is generated, and the deposit DP2 is etched by ions. Thereby, the deposit DP2 that may hinder the etching of the first region R1 is removed as shown in FIG. 23. By performing the related process ST5, in the processing after the method MT2, a well-shaped opening (lower opening LO2 described later) can be formed.

Below, various conditions in the process ST5 are illustrated.

‧Pressure inside the processing vessel: 10mTorr(1.33Pa)~50mTorr(6.65Pa)

‧Processing gas

C ₄ F ₆ gas: 4sccm~6sccm

Ar gas: 700sccm~1200sccm

O ₂ gas: 3sccm~5sccm

‧High frequency power for plasma generation: 100W~500W

‧High frequency bias power: 40W~60W

‧Processing time: 55 seconds

Next, in the method MT2, in order to etch the first region R1, the sequence SQ22 is executed more than once. The sequence SQ22 that is more than once includes the process ST21 and the process ST23 respectively. The sequence SQ22 that is more than once may individually further include the process ST22.

The individual process ST21 of the sequence SQ22 for more than one time is the same process as the individual process ST21 of the sequence SQ21 for more than one time. In the individual process ST21 of the sequence SQ22 that is more than one time, a plasma containing a process gas of fluorocarbon gas is generated. Then, the dissociated fluorocarbon is deposited on the surface of the wafer W, as shown in FIG. 24, forming a deposit DP.

In the sequence SQ22 that is more than once, the second is to implement the process ST22. The individual process ST22 of the sequence SQ22 for more than one time is the same process as the individual process ST22 of the sequence SQ21 for more than one time. Oxygen-active species are generated in the individual process ST22 of the sequence SQ22 more than once, and the amount of deposits DP on the wafer W2 is moderately reduced by the oxygen-active species as shown in FIG. 25.

In the individual sequence SQ22 that is more than one time, the second is to implement the process ST23. The individual process ST23 of the sequence SQ22 for more than one time and the individual process ST23 of the sequence SQ21 for more than one time It is the same process. The inert gas plasma is generated in the individual process ST23 of the sequence SQ22 more than once, and the ions are drawn to the wafer W2. Then, the first region R1 is etched by the fluorocarbon radicals contained in the deposit DP. Thereby, the first region R1 in the recessed portion divided by the second region R2 is etched, and as shown in FIG. 26, the lower opening LO2 is partially formed.

In the individual sequence SQ22 that is more than once, the ratio of the execution time of the process ST23 to the execution time of the process ST21 is set to be less than the ratio of the execution time of the process ST23 contained in the individual sequence SQ21 to the execution time of the process ST21. Therefore, in the sequence SQ22 that is performed more than once, the amount of the deposit DP formed on the wafer W2 is relatively increased, and the amount of etching is relatively small. According to the sequence SQ22 related more than once, when the silicon oxide covering the first region R1 above the second region R2 is removed, the second region R2 can be protected by the deposit DP (see FIG. 26).

In method MT2, in the subsequent process STJ2, it is determined whether the stopping conditions are met. The stop condition is to determine that the sequence SQ22 has been executed a predetermined number of times. In the process STJ2, when it is determined that the stop condition is not satisfied, the sequence SQ22 is executed from the process ST21. On the other hand, in the process STJ2, when it is determined that the stop condition is satisfied, the execution of the sequence SQ22 is completed more than once.

In the method MT2, secondly, in order to further etch the first region R1, the process ST6 is performed. In the process ST6 of an example, the first region R1 is etched by reactive ion etching. The process ST6 can be the same process as the process ST3 of the method MT2. When the process ST6 is executed, the second region R2 is protected by the deposit DP formed by the sequence SQ22 more than once. Therefore, in the process ST6, the first region R1 can be etched at a high etching rate while suppressing the removal of the second region R2. With this process ST6, as shown in FIG. 27, the depth of the lower opening LO2 can become deeper, and finally the first region R1 is etched until the second region R2 at the bottom of the recess is exposed.

In the process ST6 of another example, the sequence SQ23 is executed more than once as shown in FIG. 28. The sequence SQ23 that is one or more times and the sequence SQ21 and the sequence SQ22 individually include the process ST21 and the process ST23. The sequence SQ23 that is more than one time individually and the sequence SQ21 and the sequence SQ22 individually may further include the process ST22.

In the individual process ST21 of the sequence SQ23 that is performed more than once, the plasma of the process gas containing the fluorocarbon gas is generated. Then, the dissociated fluorocarbon is deposited on the surface of the wafer W to form a deposit DP. Oxygen-active species are generated in the individual process ST22 of the sequence SQ23 more than once, and the amount of deposit DP on the wafer W2 can be appropriately reduced by the oxygen-active species. Individual SQ23 sequence that is more than once In the process ST23, an inert gas plasma is generated, and the ions are drawn to the wafer W2. In addition, the first region R1 is etched by the fluorocarbon radicals contained in the deposit DP.

In addition, in the individual sequence SQ23 that is more than once, the ratio of the execution time of the process ST23 to the execution time of the process ST21 is set to be greater than the ratio of the execution time of the process ST23 contained in the individual sequence SQ22 to the execution time of the process ST21 . For example, the execution time of the individual process ST21 of the sequence SQ23 more than once and the execution time of the individual process ST21 of the sequence SQ21 more than once can be set to the same time length, and the execution time of the individual process ST23 of the sequence SQ23 more than once can be set to be longer. The execution time of the individual process ST21 of the sequence SQ22 more than one time comes to a long time length. As a result, in the individual sequence SQ23 that is more than one time, the amount of the formed deposit DP is relatively small, and the etching amount is relatively large. Therefore, the first region R1 can be etched without blocking the opening MO2, the upper opening UO2, and the lower opening LO2 of the mask MK2. In addition, as a result of the execution of the above-mentioned sequence SQ22 more than once, since the deposit DP has been formed on the second region R2, in the sequence SQ23 more than once, the second region R2 can be protected by the deposit DP. The etching of the first region R1 is performed at a high etching rate.

In the foregoing, various embodiments have been described, but it is not limited to the above embodiments, and various modifications can be made. For example, in the implementation of the method MT and the method MT2, although the high-frequency power for plasma generation is supplied to the upper electrode 30, the high-frequency power may be supplied to the lower electrode LE. In addition, in the implementation of the method MT and the method MT2, a plasma processing device other than the plasma processing device 10 can be used. Specifically, the method MT and the method MT2 can be implemented using any plasma processing device such as an inductively coupled plasma processing device or a plasma processing device that generates plasma using surface waves such as microwaves.

In addition, at least one of the sequence SQ1, the sequence SQ2, and the sequence SQ3, or the execution sequence of all the processes ST11, ST12, and ST13 can also be changed. For example, at least one or all of the sequence SQ1, the sequence SQ2, and the sequence SQ3 can be executed after the execution of the process ST13. In addition, at least one of the sequence SQ21, the sequence SQ22, and the sequence SQ23 or the execution sequence of all the processes ST21, ST22, and ST23 can be changed. For example, in at least one of the sequence SQ21, the sequence SQ22, and the sequence SQ23, or all of them, the process ST22 may be executed after the execution of the process ST23.

ST1: Etching of anti-reflective film

ST2: Etching of organic film

ST3: Etching of the first area

ST4: Plasma for generating oxygen-containing gas

ST11: Plasma for generating process gas containing fluorocarbon gas

ST12: Generate plasma of processing gas including oxygen-containing gas and inert gas

ST13: Etching of the first area

STa, STb, STc: Does the stop condition meet?

SQ1~SQ3: sequence

Claims (9)

An etching method that selectively etches a first area composed of silicon oxide with respect to a second area composed of silicon nitride by plasma treatment of the object to be processed; the object to be processed has regions The second area of the recess, the first area provided to fill the recess and cover the second area, and a mask provided on the first area, and the mask is provided on the recess with An opening with a wider width than the width of the recess; the method includes: a first sequence more than once, which is performed to etch the first region; and a second sequence more than once, to further etch the first Area, and executed after the execution of the first sequence more than once; the first sequence more than once and the second sequence more than once include: the first process, which is in the process containing the processed body The plasma of the processing gas containing fluorocarbon gas is generated in the processing container, and fluorocarbon deposits are formed on the processed body; and the second process is to interrupt the electricity of the processing gas containing the fluorocarbon gas In the state of slurry generation, the first region is etched by the fluorocarbon radicals contained in the deposit; the first sequence of more than one time is carried out during the period including the exposure of the second region; The amount of the first region individually etched by the above first sequence is less than the amount of the first region individually etched by the second sequence more than once. For example, the etching method of the first item of the scope of patent application, in order to further etch the first area, further includes the third sequence executed more than once after the second sequence is executed; the third sequence more than once is individually executed Including the first process and the second process; the first sequence of more than one time, the second sequence of more than one time, and the third sequence of more than one time individually contain the plasma that generates inert gas in the second process , By supplying high-frequency bias power to the mounting table supporting the processed body to draw ions to the processed body; the high-frequency bias power used in the second process included in the one or more third sequence Is greater than the high-frequency bias power used in the second process in the first sequence more than once and the second sequence more than once. For example, the etching method of item 2 in the scope of patent application, the first sequence of more than one time, The second sequence of more than one time and the third sequence of more than one time individually further include a third process, which is to generate electricity including oxygen-containing gas and inert gas in the processing container containing the object to be processed Pulp. An etching method that selectively etches the first region of the processed body composed of silicon oxide with respect to the second region of the processed body composed of silicon nitride; the processed body is applied before the method The initial state has: the second area that delimits the recess, the first area set to fill the recess and cover the second area, and a mask set on the first area, the mask The concave portion is provided with an opening having a wider width than the width of the concave portion; the method includes: a first sequence more than once, which is performed to etch the first area; a second sequence more than once, is In order to further etch the first area, the process performed after the execution of the first sequence more than once; and the process of etching the first area after the execution of the second sequence more than once; The first sequence individually and the more than one second sequence individually include: the first process, which generates plasma containing fluorocarbon gas processing gas, and forms a fluorocarbon deposit on the processed body; and the second process, The first area is etched by the fluorocarbon radicals contained in the deposit; the first sequence of more than one time includes the second process individually and the time of execution of the second process is included in the first sequence of more than one time. The ratio of the execution time of the process is greater than the ratio of the execution time of the second process included in the second sequence of more than one time to the execution time of the first process included in the second sequence of more than one time. For example, the etching method of item 4 of the scope of patent application, after the execution of the first sequence more than once and before the execution of the second sequence more than once, further includes: forming the mask on the material containing the mask The deposit on the processing body is subjected to a reactive ion etching process. For example, in the etching method of item 4 or 5 of the scope of patent application, in the process of etching the first area, the first area is etched by reactive ion etching. For example, the etching method of item 6 in the scope of patent application, wherein the first sequence of more than one time is And the second sequence of more than one time further includes a third process, which is to generate plasma including oxygen-containing gas and inert gas processing gas to reduce the deposit of fluorocarbon. For example, the etching method of item 4 or 5 of the scope of patent application, wherein the process of further etching the first area includes: implementing a third sequence including the first process and the second process separately; The ratio of the execution time of the second process included in the 3 sequence to the execution time of the first process included in the third sequence more than once is greater than the execution time of the second process included in the second sequence more than once. The ratio of the execution time of the first process contained in the second sequence more than once. For example, the etching method of item 8 in the scope of patent application, wherein the first sequence of more than one time, the second sequence of more than one time, and the third sequence of more than one time individually further include a third process, and the generation includes oxygen-containing gas and Plasma of inert gas processing gas reduces the deposit of fluorocarbon.

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