TWI684218B - Etching method (3) - Google Patents

Abstract

The opening can be prevented from being blocked, and the first region composed of silicon oxide is etched relative to the second region composed of silicon nitride.

The method of an embodiment includes the first step of generating a fluorocarbon-containing process gas plasma in a processing container accommodating a processed body, and forming a fluorocarbon-containing deposit on the processed body; The second step is to generate a plasma containing a processing gas containing an oxygen-containing gas and an inert gas in a processing container that houses the object to be processed; and, the third step is to generate fluorocarbon radicals contained in the sediment To etch the first area. In this method, a mechanism including the first step, the second step, and the third step is repeatedly executed.

Description

Etching method (3)

An embodiment of the present invention relates to an etching method, and in particular to a first structure composed of selectively etching silicon oxide with respect to a second area composed of silicon nitride by plasma treatment of a body to be processed The etching method of the area.

In the manufacture of electronic components, the process of forming openings of holes or trenches is performed relative to the area composed of silicon oxide (SiO ₂ ). In this process, as described in US Patent No. 7,708,859, in general, the treated body is exposed to a plasma of fluorocarbon gas to etch the region.

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

The system to be processed by SAC technology has a first region made of silicon oxide, a second region made of silicon nitride, and a mask. The second area is provided to define the concave portion, the first area is provided to fill the concave portion and cover the second area, and the mask is provided on the first area to provide an opening in the concave portion. In the conventional SAC technology, as described in Japanese Patent Laid-Open No. 2000-307001, for the etching of the first region, a plasma of a processing gas containing fluorocarbon gas, oxygen gas, and rare gas is used. By exposing the object to be processed to the plasma of the processing gas, the first region of the portion 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 part surrounded by the second region, that is, the first region in the recess, is etched in a self-integrating manner. In this way, a self-integrated continuous opening below the upper opening is formed.

【Prior Technical Literature】

【Patent Literature】

Patent Document 1: Specification of US Patent No. 7708859

Patent Document 2: Japanese Patent Laid-Open No. 2000-307001

In the above-mentioned prior art, when etching the first area, the openings formed by the mask opening and/or the etching of the first area are narrowed due to the deposits from the fluorocarbon. Depending on the situation, these openings may be Occlusion. As a result, the etching rate of the first region is reduced, and depending on circumstances, the etching of the first region is stopped.

Therefore, it is sought to prevent the opening from being blocked, and to etch the first region composed of silicon oxide with respect to the second region composed of silicon nitride.

In the same manner, it provides an etching method for selectively etching the first region composed of silicon oxide with respect to the second region composed of silicon nitride by plasma treatment of the object to be processed. The system to be processed has a second area that defines a recess, a first area that fills the recess and is provided so as to cover the second area, and a mask provided on the first area. This method includes: (a) The first step is to generate a fluorocarbon-containing process gas plasma in the processing container that houses the object to be processed, and a fluorocarbon-containing deposit will be formed on the object to be processed; ( b) The second step is to generate the plasma of the processing gas containing oxygen-containing gas and inert gas in the processing container that houses the object to be processed; and, (c) The third step is to contain the Fluorocarbon radicals etch the first area. In this method, a mechanism including the first step, the second step, and the third step is repeatedly executed.

The above-mentioned method related to the same state will form a fluorocarbon-containing deposit on the surface of the object to be processed in the first step, and etch the first region by the fluorocarbon radicals in the deposit in the third step, and The mechanism including the first step and the third step will be repeatedly implemented. Then, this method will appropriately reduce the amount of deposits by performing the second step, using oxygen-based active groups. Therefore, it is possible to prevent the opening of the mask opening and the first region from being blocked. Moreover, in this method, since the oxygen-containing gas in the processing gas is diluted by the inert gas, it is possible to suppress excessive removal of the deposit.

In one embodiment, the mask is composed of an organic material; the mask is provided with a silicon-containing antireflection film. The method of this embodiment further includes: (d) a fourth step in which a plasma generating a fluorocarbon-containing processing gas is etched in the processing container before the second area is exposed; and, ( e) The fifth step is to generate the plasma of the processing gas containing oxygen-containing gas in the processing container. This mechanism is implemented after the execution of the fourth step and the fifth step. In this embodiment, the fourth step removes the silicon-containing anti-reflection film at the same time as the etching of the first region. Then, by The active radical of the oxygen generated in the fifth step widens the opening width of the mask. In this way, even if deposits are attached to the mask surface that defines the opening, the reduction in the width of the opening can still be reduced.

In one embodiment, the second step is performed for 2 seconds or more at a time, and in the second step, the deposit is etched at a rate of 1 nm/second or less. In order to use the plasma processing device to implement the above mechanism, it takes time to switch the gas between the first to third steps. Therefore, the second step needs to be performed for more than 2 seconds, but when the etching rate of the second step is too high for such a length of time, the deposits used to protect the second area may be excessively removed. By etching the deposit at a rate of 1 nm/sec or less in the second step, the amount of deposit formed on the body to be processed can be adjusted appropriately.

In the mechanism of an embodiment, the second step is executed between the first step and the third step; the mechanism further includes other steps, which are generated in the processing container that houses the object to be processed, containing oxygen-containing gas and inert gas The plasma of the processing gas. During the execution of the third step, a substance that constitutes a deposit adhering to the object to be processed will be released, and the substance will adhere to the object to be processed again to form an opening width formed by etching of the mask opening and the first region Narrowed deposits, depending on the situation, will also block these openings. According to this embodiment, the object to be treated is exposed to active radicals of oxygen after the third step is performed, so that deposits that narrow the width of the opening can be reduced, and blocking of the opening can be prevented more reliably.

As described above, the opening can be prevented from being blocked, and the first region composed of silicon oxide can be etched with respect to the second region composed of silicon nitride.

10‧‧‧Plasma processing device

12‧‧‧Handling container

30‧‧‧Upper electrode

PD‧‧‧Placing table

LE‧‧‧Lower electrode

ESC‧‧‧Static fixture

40‧‧‧Gas source group

42‧‧‧ valve group

44‧‧‧Flow controller group

50‧‧‧Exhaust

62‧‧‧The first high frequency power supply

64‧‧‧The second high frequency power supply

Cnt‧‧‧Control Department

W‧‧‧ Wafer

R1‧‧‧ Region 1

R2‧‧‧ Region 2

OL‧‧‧Organic film

AL‧‧‧Silicone anti-reflective film

MK‧‧‧Mask

DP‧‧‧Sediment

FIG. 1 is a flowchart showing an etching method related to an embodiment.

2 is a cross-sectional view illustrating an object to be processed to which an etching method according to an embodiment is applied.

FIG. 3 is a schematic diagram showing an example of a plasma processing apparatus that can be used to implement the method shown in FIG. 1.

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

FIG. 6 is a cross-sectional view of the object to be processed during the implementation of the method shown in FIG. 1.

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

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

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

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

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

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

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

FIG. 17 is a flowchart showing an etching method related to other embodiments.

FIG. 18 is a cross-sectional view of the object to be processed after step ST14 of the method shown in FIG. 17 is performed.

FIG. 19 is a cross-sectional view showing the object to be processed after step ST14 of the method shown in FIG. 17 is performed.

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

FIG. 1 is a flowchart showing an etching method related to an embodiment. The method MT shown in FIG. 1 is an etching method for selectively etching the first region composed of silicon oxide with respect to the second region composed of silicon nitride by plasma treatment of the object to be processed.

2 is a cross-sectional view illustrating an object to be processed to which an etching method according to an embodiment is applied. 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 that constitutes a mask thereafter. In one example, the wafer W may be obtained in the process of manufacturing a chip field effect transistor. Further, it has a raised area RA, a silicon-containing antireflection film AL, and a resist mask RM.

The raised area RA is provided to be raised from the substrate SB. This raised area RA may constitute, for example, a gate area. 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 define a concave portion. 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 composed of silicon oxide (SiO ₂ ) and is provided on the second region R2. Specifically, the first region R1 fills the concave portion defined by the second region R2 and is provided so as to cover the second region.

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 provided on the anti-reflection film AL. The resist mask RM provides an opening having a wider width than the width of the recess in the recess 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 body like the wafer W shown in FIG. 2 is processed in the plasma processing apparatus. FIG. 3 is a schematic diagram showing an example of a plasma processing apparatus that can be used to implement the method shown in FIG. 1. The plasma processing apparatus 10 shown in FIG. 3 is a capacitive coupling type plasma etching apparatus, and includes a substantially cylindrical processing container 12. The inner wall surface of the processing container 12 is composed of, for example, anodized aluminum. The processing container 12 is securely grounded.

A support portion 14 having a substantially cylindrical shape is provided on the bottom of the processing container 12. The support portion 14 is made of, for example, an insulating material. The support 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 portion 14.

The mounting table PD will hold the wafer W thereon. The mounting table PD has a lower electrode LE and an electrostatic jig ESC. The lower electrode LE includes a first plate 18a and a second plate 18b. The first plate body 18a and the second plate body 18b are made of metal such as aluminum and formed into a substantially disc shape. The second plate body 18b is provided on the first plate body 18a and electrically connected to the first plate body 18a.

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

A focus ring FR is provided on the peripheral portion of the second plate body 18b so as to surround the edge of the wafer W and the electrostatic jig WSC. The focus ring FR is designed to improve the uniformity of etching. The focus ring FR is made of a material appropriately selected according to the material of the film to be etched, for example, it can be made of quartz.

The refrigerant flow path 24 is provided inside the second plate body 18b. The refrigerant flow path 24 constitutes a temperature adjustment mechanism. The refrigerant flow path 24 will pass through the piping 26a from the cooling unit provided outside the processing container 12 And the refrigerant is supplied. The refrigerant supplied to the refrigerant flow path 24 returns to the cooling unit through the piping 26b. In this way, refrigerant will circulate between the refrigerant channel 24 and the cooling unit. By controlling the temperature of this refrigerant, the temperature of the wafer W supported by the electrostatic fixture ESC can be controlled.

In addition, the plasma processing apparatus 10 is provided with a gas supply line 28. The gas supply line 28 supplies heat transfer gas from the heat transfer gas supply mechanism, such as He gas, between the upper surface of the electrostatic jig 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 placed above the mounting table PD, and is arranged to face the mounting table PD. The lower electrode LE and the upper electrode 30 are arranged slightly parallel to each other. A processing space S for plasma processing of the wafer W is provided between the upper electrode 30 and the lower electrode LE.

The upper electrode 30 is supported on the upper portion of the processing container 12 through an insulating shield member 32. In one embodiment, the upper electrode 30 may be configured to change the vertical distance from the upper surface of the mounting table PD, that is, the wafer mounting surface. 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 a plurality of gas ejection holes 34a are provided in the electrode plate 34. In one embodiment, the electrode plate 34 is made of silicon.

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

The gas supply pipe 38 is connected to the gas source group 40 through the valve group 42 and the flow controller group 44. The gas source group 40 contains plural 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. In one example, more than one fluorocarbon gas source may contain a C ₄ F ₈ gas source, a CF ₄ gas source, and a C ₄ F ₆ gas source. The rare gas source may be any rare gas source of He gas, Ne gas, Ar gas, Kr gas, and Xe gas. In one example, it is an Ar gas source. Furthermore, in one example, the oxygen-containing gas source may be an oxygen gas (O ₂ gas) source. In addition, the oxygen-containing gas may be any gas containing oxygen, for example, it may be a carbon oxide gas of CO gas or CO ₂ gas.

The valve group 42 includes plural valves, and the flow controller group 44 includes plural flow controllers called mass flow controllers. The plural gas sources of the gas source group 40 will respectively pass through the corresponding valves and flow rates of the valve group 42 The corresponding flow controllers of the controller group 44 are connected to the gas supply pipe 38.

In addition, in the plasma processing apparatus 10, a sediment cover 46 is detachably provided along the inner wall of the processing container 12. The deposit mask 46 is also provided on the outer periphery of the support portion 14. The deposit mask 46 prevents etching by-products (deposits) from adhering to the processing container 12, and may be made of ceramic coated with Y ₂ O ₃ or the like on an aluminum material.

On the bottom side of the processing container 12, and between the support portion 14 and the side wall of the processing container 12, an exhaust plate 48 is provided. The exhaust plate body 48 may be made of ceramic coated with Y ₂ O ₃ or the like on an aluminum material, for example. An exhaust port 12e is provided below the exhaust plate body 48 and at the processing container 12. The exhaust port 12e is connected to the exhaust device 50 through the exhaust pipe 52. The exhaust device 50 is a vacuum pump with a turbo molecular pump or the like, which can depressurize the space in the processing container 12 to a desired vacuum degree. In addition, the side wall of the processing container 12 is provided with a carrying-out port 12g of the wafer W. The carrying-out port 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, and generates high-frequency power at a frequency of, for example, 27 to 100 MHz. The first high-frequency power source 62 is connected to the upper electrode 30 through the matching device 66. The matching device 66 is a circuit for integrating the output impedance of the first high-frequency power source 62 and the input impedance of the load side (upper electrode 30 side). In addition, the first high-frequency power supply 62 may be connected to the lower electrode LE through the matching device 66.

The second high-frequency power supply 64 generates high-frequency bias power for attracting ions to the wafer W, and generates high-frequency bias power at a frequency in the range of 400 kHz to 13.56 MHz, for example. The second high-frequency power supply 64 is connected to the lower electrode LE through the matching device 68. The matching device 68 is a circuit for integrating the output impedance of the second high-frequency power supply 64 and the input impedance of the load side (lower electrode LE side).

In addition, the plasma processing apparatus 10 further has a power supply 70. The power supply 70 is connected to the upper electrode 30. The power supply 70 applies a voltage for attracting positive ions existing in the processing space S to the electrode plate 34 to the upper electrode 30. In one example, the power supply 70 is a DC power supply that generates a negative DC voltage. In another example, the power supply 70 may also be an AC power supply that generates a lower frequency AC voltage. The voltage applied to the upper electrode from the power source may be a voltage of -150V or less. That is, the voltage applied by the power supply 70 to the upper electrode 30 may be a negative voltage with an absolute value of 150 or more. When the voltage is applied to the upper electrode 30 by the power supply 70, the positive ions existing in the processing space S will collide with the electrode plate 34. As a result, secondary electrons and/or silicon are released from the electrode plate 34. The released silicon will combine with the fluorine active groups present in the processing space S, thereby reducing the amount of fluorine active groups.

Furthermore, 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, and the like, and controls each part of the plasma processing apparatus 10. In this control unit Cnt, the operator can perform command input operations for managing the plasma processing device 10, etc., and the display device can visually display the operating status of the plasma processing device 10. Furthermore, the memory part of the control part Cnt stores a control program for allowing the processor to control various processes performed by the plasma processing apparatus 10, or to allow each part of the plasma processing apparatus 10 to execute processing corresponding to the processing conditions The program, that is, processing recipes.

Hereinafter, referring to FIG. 1 again, the method MT will be described in detail. In the following description, reference will be made to FIGS. 2, 4 to 16 as appropriate. 4 to 16 are cross-sectional views showing the body to be processed in the middle of the implementation of the method MT. In the following description, in the method MT, an example of processing the wafer W shown in FIG. 2 using the plasma processing apparatus 10 shown in FIG. 3 will be described.

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

Hereinafter, various conditions in step ST1 will be exemplified.

‧Pressure in 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 step ST1, plasma for processing gas is generated, and the fluorocarbon active group is used to etch the The agent masks the reflection preventing film AL of the exposed portion of the RM opening. As a result, as shown in FIG. 4, in the entire area of the anti-reflection film AL, the part exposed from the opening of the resist mask RM is removed. That is, the pattern of the resist mask RM is transferred to the anti-reflection film AL, and a pattern providing an opening is formed in the anti-reflection film AL. In addition, the operation of each part of the plasma processing apparatus 10 in step ST1 can be controlled by the control part Cnt.

Next, in step ST2, the organic film OL is etched. Therefore, in step ST2, the processing gas is supplied into the processing container 12 from the gas source selected from the plural gas sources of the gas source group 40. This processing gas may contain hydrogen and nitrogen. In addition, as long as the processing gas used in the step ST2 can etch the organic film, it may be another gas, for example, a processing gas containing oxygen. In step ST2, the exhaust device 50 is activated, and the pressure in the processing container 12 is set to a predetermined pressure. Furthermore, in step ST2, the high-frequency power from the first high-frequency power supply 62 is supplied to the upper electrode 30, and the high-frequency bias power from the second high-frequency power supply 64 is supplied to the lower electrode LE.

Hereinafter, various conditions in step ST2 will be exemplified.

‧Pressure in 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 step ST2, plasma of the processing gas is generated, and the organic film OL exposed from the opening of the anti-reflection film AL is etched. Also, the resist mask RM will also be etched. As a result, as shown in FIG. 5, the resist mask RM is removed, and the portion of the organic film OL exposed from the opening of the anti-reflection film AL is removed. That is, the pattern of the anti-reflection film AL is transferred to the organic film OL, and a pattern is provided in the organic film OL to provide the opening MO, and the mask MK is generated from the organic film OL. In addition, the operation of each part of the plasma processing apparatus 10 in step ST2 can be controlled by the control part Cnt.

In one embodiment, step ST3 is executed after the execution of step ST2. In step ST3, the first region R1 is etched until the second region R2 is exposed. In other words, the first region R1 is etched so that only a small amount of the first region R1 remains on the second region R2. Therefore, in step ST3, the processing gas is supplied to the processing volume from the gas source selected from the plural gas sources of the gas source group 40 器12内。 12 inside. This process gas contains fluorocarbon gas. In addition, the processing gas may further contain a rare gas, such as Ar gas. Furthermore, the processing gas may further contain oxygen. In step ST3, the exhaust device 50 is activated, and the pressure in the processing container 12 is set to a predetermined pressure. In step ST3, the high-frequency power from the first high-frequency power supply 62 is supplied to the upper electrode 30, and the high-frequency bias power from the second high-frequency power supply 64 is supplied to the lower electrode LE.

In step ST3, plasma of the processing gas is generated, and the first region R1 exposed from the opening of the mask MK is etched by the fluorocarbon active group. The processing time of this step ST3 is set so that when the step ST3 is completed, the first region R1 will remain on the second region R2 with a predetermined film thickness. As shown in FIG. 6, the result of performing this step ST3 may partially form the upper opening UO. In addition, the operation of each part of the plasma processing apparatus 10 in step ST3 can be controlled by the control part Cnt.

Therefore, in the step ST11 described later, the formation of the fluorocarbon-containing deposit on the surface of the wafer W containing the first region R1 will be a mode that has priority over the etching of the first region R1, that is, the deposition mode condition. On the other hand, in step ST3, the mode in which the etching of the first region R1 is given priority over the formation of the deposit is selected, that is, the condition for the etching mode. Therefore, in an example, the fluorocarbon gas used in step 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 system of this example (i.e., the number of fluorine atoms/number of carbon atoms) is higher than the ratio of the number of fluorine atoms to the number of carbon atoms of the fluorocarbon gas used in step ST11 ( That is, the number of fluorine atoms/number of carbon atoms is higher than that of fluorocarbon gas. Furthermore, in an example, in order to improve the dissociation degree of fluorocarbon gas, the high-frequency power for plasma generation used in step ST3 may be set to be larger than the high-frequency power for plasma generation used in step ST11. According to these examples, the etching mode can be realized. Also, in an example, the high-frequency bias power used in step ST3 may be set to a power larger than the high-frequency bias power in step ST11. According to this example, the energy that ions are attracted to the wafer W can be increased, and the first region R1 can be etched at high speed.

Hereinafter, various conditions in step ST3 will be exemplified.

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

In step ST4, an oxygen active group is generated, and the oxygen active group makes the opening MO covering the MK wider at the upper end portion. Specifically, as shown in FIG. 7, the upper shoulder of the mask MK that defines the upper end portion of the opening MO is etched in a tapered manner. In this way, even if the deposits generated in the subsequent process adhere to the surface that defines the opening MO of the mask MK, the reduction in the width of the opening MO can be reduced. In addition, the operation of each part of the plasma processing apparatus 10 in step ST4 can be controlled by the control part Cnt.

Therefore, in step ST12 described later, it is necessary to reduce trace deposits formed in each mechanism, and it is necessary to suppress excessive reduction of the deposits. On the other hand, in step ST4, since it is performed to expand the width of the upper end portion of the opening MO of the mask MK, it is required to reduce the processing time.

Hereinafter, various conditions in step ST4 will be exemplified.

‧Pressure in 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

Next, in the method MT, in order to etch the first region R1, the mechanism SQ is repeatedly implemented. The mechanism SQ includes step ST11, step ST12, and step ST13 in this order.

In the mechanism SQ, the process ST11 is first executed. In step ST11, the wafer W is stored The plasma of the processing gas is generated in the processing container 12 of. Therefore, in step ST11, the processing gas is supplied into the processing container 12 from the gas source selected from the plural gas sources of the gas source group 40. This process gas contains fluorocarbon gas. In addition, the processing gas may further contain a rare gas, such as Ar gas. In step ST11, the exhaust device 50 is activated to set the pressure in the processing container 12 to a predetermined pressure. In step ST11, high-frequency power from the first high-frequency power source 62 is applied to the upper electrode 30. As a result, a plasma of a processing gas containing fluorocarbon gas is generated, and the dissociated fluorocarbon is deposited on the surface of the wafer W, as shown in FIG. 8 to form a deposit DP. The operation of each part of the plasma processing apparatus 10 in the related step ST11 can be controlled by the control part Cnt.

As described above, in step ST11, the conditions for the deposition mode are selected. Therefore, in one example, C ₄ F ₆ gas is used as the fluorocarbon gas.

Hereinafter, various conditions in step ST11 will be exemplified.

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

‧Processing gas

C ₂ F ₆ gas: 2sccm~10sccm

Ar gas: 500sccm~1500sccm

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

‧High frequency bias power: 0W

In the method MT, the process ST12 is then executed. In step ST12, a plasma containing a processing gas containing an oxygen-containing gas and an inert gas is generated in the processing container 21. Therefore, in step ST12, the processing gas is supplied into the processing container 12 from the gas source selected from the plural gas sources of the gas source group 40. In one example, the process gas system contains oxygen as an oxygen-containing gas. Also, in an example, the process gas system contains a rare gas called Ar gas as an inert gas. The inert gas can also be nitrogen. In step ST12, the exhaust device 50 is activated to set the pressure in the processing container 12 to a predetermined pressure. In step ST12, high-frequency power from the first high-frequency power source 62 is supplied to the upper electrode 30. In step ST12, the high-frequency bias power from the second high-frequency power supply 64 may not be supplied to the lower electrode LE.

In step ST12, oxygen active groups are generated, and due to the oxygen active groups, the amount of the deposit DP on the wafer W is appropriately reduced as shown in FIG. 9. As a result, the opening MO and the upper opening UO are prevented from being blocked by the excessive deposit DP. In addition, the processing used in step ST12 In the gas, oxygen will be diluted by the inert gas, so that the excessive removal of the deposit DP can be suppressed. The operation of each part of the plasma processing apparatus 10 in the related step ST12 can be controlled by the control part Cnt.

Hereinafter, various conditions in step ST12 will be exemplified.

‧Pressure in 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, the process ST12 of each mechanism, that is, the process ST12 is performed for 2 seconds or more at a time, and the deposit DP in the process S12 can be etched at a rate of 1 nm/second or less. When the above mechanism is implemented using a plasma processing apparatus like the plasma processing apparatus 10, a gas switching time is required for the transition between each of the steps ST11, ST12, and ST13. Therefore, considering the time required for the discharge to stabilize, step ST12 needs to be performed for 2 seconds or more. However, during such a long period of time, if the etching rate of the deposit DP is too high, the deposit for protecting the second region R2 may be excessively removed. Therefore, in step ST12, the deposit DP is etched at a rate of 1 nm/sec or less. Thereby, the amount of the deposit DP formed on the wafer W can be adjusted appropriately. In addition, the etching of the deposit DP in the process ST12 is a rate of 1 nm/sec or less from the pressure in the processing vessel, the degree to which the oxygen in the processing gas is diluted by the rare gas, that is, the oxygen concentration, and the high-frequency power for plasma generation To meet the above conditions.

Next, in step ST13, the first region R1 is etched. Therefore, in step ST13, the processing gas is supplied into the processing container 12 from the gas source selected from the plural gas sources of the gas source group 40. This process gas system contains inert gas. In one example, the inert gas may be a rare gas called Ar gas. Alternatively, the inert gas may be nitrogen. In step ST13, the exhaust device 50 is activated to set the pressure in the processing container 12 to a predetermined pressure. In step ST13, the high-frequency power from the first high-frequency power source 62 is supplied to the upper electrode 30. In step ST13, the high-frequency bias power from the second high-frequency power supply 64 is supplied to the lower electrode LE.

Hereinafter, various conditions in step ST13 will be exemplified.

‧Pressure in 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 step ST13, plasma of inert gas is generated, and ions are attracted to the wafer W. Then, the first region R1 is etched by the fluorocarbon radical contained in the deposit DP. As a result, as shown in FIG. 10, the first region R1 in the recess provided by the second region R2 is etched, and the lower opening LO is gradually formed. The operation of each part of the plasma processing apparatus 10 in the related step ST13 can be controlled by the control part Cnt.

In the method MT, the mechanism SQ including the above steps ST11 to ST13 is repeated. Then, as the mechanism SQ is repeated, as shown in FIG. 11, a deposit DP is formed on the wafer W due to the execution of the process ST11. Then, as shown in FIG. 12, the amount of the deposit DP is reduced by the execution of the process ST12. Then, as shown in FIG. 13, the first region R1 is further etched due to the execution of step ST13 so that the depth of the lower opening LO becomes deeper. Further, as the mechanism SQ is further repeated, as shown in FIG. 14, a deposit DP is formed on the wafer W due to the execution of the process ST11. Then, as shown in FIG. 15, the amount of deposit DP is reduced due to the execution of step ST12. Then, as shown in FIG. 16, the first region R1 is further etched due to the execution of the step ST13, so that the depth of the lower opening LO becomes deeper. Finally, the first region R1 is etched until the second region R2 at the bottom of the recess is exposed.

Returning to FIG. 1, in the method MT, it is judged whether the stop condition is satisfied in the process STa. The stop condition is a case where it is judged that the mechanism SQ has fulfilled a predetermined number of times. In step STa, when it is determined that the stop condition is not satisfied, the mechanism SQ is implemented from step ST11. On the other hand, in step STa, when it is determined that the stop condition is satisfied, the execution of the method MT is ended.

In one embodiment, the mechanism SQ (hereinafter referred to as the "first mechanism") that can be implemented during the period when the second region R2 is exposed can be used. The condition for the mechanism SQ to repeat is set so that the etching amount of the first region R1 in the "second mechanism" is small. In one example, the execution time of the first mechanism is set to be shorter than that of the second mechanism. In this example, the ratio of the execution time length of step ST11, the execution time length of step ST12 and the execution time length of step ST13 in the first mechanism can be set to be equal to the execution time length of step ST11 and the execution of step ST12 in the second mechanism The ratio of the time length and the execution time length of the process ST13. For example, in the first mechanism, the execution time length of step ST11 is from The time length in the range of 2 seconds to 5 seconds is selected. The execution time length of step ST12 is selected from the time length in the range of 2 seconds to 5 seconds. The execution time length of step ST13 is the time in the range of 5 seconds to 10 seconds. To choose the length. Furthermore, in the second mechanism, the execution time length of step ST11 is selected from a time length in the range of 2 seconds to 10 seconds, and the execution time length of step ST12 is selected from a time length in the range of 2 seconds to 10 seconds. The execution time length of ST13 is selected from the time length ranging from 5 seconds to 20 seconds.

Although the fluorocarbon active group generated in step S11 is deposited on the second region R2 to protect the second region R2, when the first region R1 is etched to expose the second region R2, the second region R2 may be etched. Therefore, in one embodiment, the first mechanism is implemented during the exposure period of the second region R2. As a result, the amount of etching is suppressed and a deposit DP is formed on the wafer W, and the second region R2 is protected by the deposit DP. However, after that, a second mechanism with a larger etching amount will be implemented. Therefore, according to this embodiment, the reduction of the second region R2 can be suppressed, and the first region R1 can be etched.

In addition, in the process ST13 of the mechanism SQ (hereinafter referred to as the "third mechanism") that is executed after the second mechanism is implemented, the high-frequency bias power can be set to be higher than that used in the process ST13 of the first mechanism and the second mechanism High-frequency bias power requires large power. For example, in the step ST13 of the first mechanism and the second mechanism, the high-frequency bias power is set at 20W~100W, and in the step ST13 of the third mechanism, the high-frequency bias power is set at 100W~300W. In addition, in the third mechanism of an example, the execution time length of the process ST11 is selected from a time length in the range of 2 seconds to 10 seconds, and the execution time length of the process ST12 is selected from a time length in the range of 2 seconds to 10 seconds. Selection, the execution time length of the process ST13 is selected from the time length in the range of 5 seconds to 15 seconds.

As shown in FIG. 14, after the first mechanism and the second mechanism are implemented, the amount of deposit DP on the wafer W will become quite large. When the amount of the deposit DP becomes larger, the width of the opening MO, the width of the upper opening UO, and the width of the lower opening LO become narrower due to the deposit DP. Therefore, the flow rate of ions reaching the deep part of the lower opening LO may be insufficient. However, since step ST13 of the third mechanism uses a large high-frequency bias power, the energy of ions attracted to the wafer W is increased. As a result, even if the lower opening LO is deep, ions can still be supplied to the deep portion of the lower opening LO.

Hereinafter, the etching methods related to other embodiments will be described. FIG. 17 is a flowchart showing an etching method related to other embodiments. 18 and 19 are cross-sectional views showing the body to be processed after step ST14 of the method shown in FIG. 17 is performed. FIG. 18 shows the cross-sectional state of the wafer after performing the process ST14 for the wafer W shown in FIG. 10, and FIG. 19 shows the wafer shown in FIG. 13 W The cross-sectional state of the wafer after the process ST14 is performed. The method MT2 shown in FIG. 17 is different from the method MT in that the mechanism SQ further includes the step ST14 executed after the step ST13 is executed. This step ST14 is the same as the step ST12. The conditions of the process of the process S14 can adopt the above conditions regarding the process of the process ST12.

As described above, in step ST13, ions are attracted to the wafer W. As a result, the substance constituting the deposit DP will be released from the wafer W, and the substance will adhere to the wafer W again, as shown in FIGS. 10 and 13, in such a manner as to narrow the width of the opening MO and the lower opening LO To form the deposit DP. Depending on the situation, this deposit DP will also block the opening MO and the lower opening LO. In the method MT2, by performing the process ST14, the wafer W shown in FIGS. 10 and 13 is exposed to the active group of oxygen in the same manner as in the process ST12. This can reduce the deposit DP (see FIGS. 10 and 13) that narrows the width of the opening MO and the lower opening LO as shown in FIGS. 18 and 19, and can more reliably prevent the opening MO and the lower opening LO Occlusion.

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

In addition, the execution order of step ST11, step ST12, and step ST13 in the mechanism SQ of the method MT may be changed. For example, in the mechanism SQ of the method MT, the process ST12 may be executed after the process ST13 is executed.

MT‧‧‧Method

SQ‧‧‧ mechanism

ST1‧‧‧Anti-reflection film etching

ST2‧‧‧Etching of organic film

ST3‧‧‧Etching of the first area

ST4‧‧‧Plasma generating oxygen-containing gas

ST11 ‧‧‧ Plasma generating process gas containing fluorocarbon gas

ST12‧‧‧ Produce plasma containing oxygen-containing gas and inert gas

ST13‧‧‧Etching of the first area

Does STa‧‧‧ meet the stop condition?

Claims (5)

An etching method is an etching method for selectively etching the first region composed of silicon oxide with respect to the second region composed of silicon nitride by plasma treatment of the object to be processed, the processed system has The second region that defines the recess, the first region that fills the recess and is arranged to cover the second region, and the mask provided on the first region, the etching method includes: The first step is to generate a fluorocarbon-containing process gas plasma in the processing container that houses the object, and a fluorocarbon-containing deposit will be formed on the object; the second step is to store the object In the processing container of the processing body, a plasma containing a processing gas containing an oxygen-containing gas and an inert gas is generated; and, in the third step, the first region is etched by the fluorocarbon radicals contained in the deposit; The mechanism including the first step, the second step, and the third step is repeatedly executed in sequence. For example, the etching method of the first patent application, where the mask is made of organic materials; the mask is provided with a silicon-containing anti-reflection film; further contains: the fourth step, which is produced in the processing container The plasma of the processing gas containing fluorocarbon gas will etch the first area before the second area is exposed; and, in the fifth step, a plasma containing the processing gas containing oxygen-containing gas is generated in the processing vessel; After the implementation of the fourth step and the fifth step, the mechanism will be implemented. For example, the etching method according to item 1 of the patent application scope, wherein the second process will be performed for more than 2 seconds at a time, and the deposit will be etched at a rate of 1 nm/second or less in the second process. For example, the etching method of claim 2 of the patent application, wherein the second step will be performed for more than 2 seconds at a time, and the second step will etch the deposit at a rate of 1 nm/second or less. The etching method as described in any one of the patent application items 1 to 4, wherein the mechanism further includes other steps, which are to generate a processing gas containing an oxygen-containing gas and an inert gas in the processing container containing the object to be processed Plasma.

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