JP2002110650A - Plasma etching method and plasma etching apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma etching method and a plasma etching apparatus which can carry out proper etching according to the film to be etched. SOLUTION: Plasma of treatment gas comprising fluorine is formed by forming a high-frequency electric field between first and second electrodes 21, 5, with a substrate being supported by the second electrode 5 by using a device hiving the first and second electrodes 21, a counterposed inside a chamber 2, a first high-frequency power supply 40 for applying high-frequency power with a frequency of 100 MHz or higher to the first electrode 21 and a second high-frequency power supply 42 for applying high-frequency power with frequency of 3 MHz or lower to the first electrode 21. When the film on a substrate W is subjected to plasma etching by means of the plasma, plasma is formed by high-frequency power from the first high-frequency power supply 40, and the magnitude of high-frequency power from the second high-frequency power supply 42 is controlled according to the film to be etched.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a plasma etching method and a plasma etching apparatus for performing a plasma etching process on a film on a substrate such as a semiconductor substrate.

[0002]

2. Description of the Related Art For example, in a semiconductor device manufacturing process, a plasma etching process is employed to form a circuit on a semiconductor wafer which is a substrate to be processed. Various apparatuses are used as apparatuses for performing the plasma etching process, and among them, a capacitively coupled parallel plate plasma etching apparatus is mainly used.

In a capacitively coupled parallel plate plasma etching apparatus, a pair of parallel plate electrodes (upper and lower electrodes) are arranged in a chamber, a processing gas is introduced into the chamber, and a high frequency is applied to one of the electrodes. A high-frequency electric field is formed between the electrodes, and a plasma of a processing gas is formed by the high-frequency electric field, and a film on the semiconductor wafer is subjected to plasma etching.

In recent years, design rules in ULSI have been increasingly miniaturized, and a hole shape having a higher aspect ratio has been demanded. Accordingly, it has been demanded to establish an etching condition corresponding to the aspect ratio.

Therefore, the frequency of the applied high frequency power is set to 6
Attempts have been made to increase the frequency to about 0 MHz and to form high-density plasma while maintaining a good plasma dissociation state. As a result, appropriate plasma can be formed under lower pressure conditions, so that it is possible to appropriately cope with further miniaturization of design rules.

[0006]

However, even in an etching apparatus having such a high characteristic, when an attempt is made to etch a multilayer film, the etching characteristics differ depending on the material of each film, and a desired shape is obtained. It is difficult to form holes.

Specifically, this type of plasma etching apparatus generally obtains a desired etching shape by a balance between an etching action by plasma and a protection action by deposition of a reaction product, but the action depends on the material of the film. It is difficult to form holes of a desired shape in a multilayer film made of different materials by plasma etching at different degrees.

The present invention has been made in view of such circumstances, and has as its object to provide a plasma etching method and a plasma etching apparatus capable of performing appropriate etching according to a film to be etched.

[0009]

In order to solve the above-mentioned problems, the present invention comprises a first electrode and a second electrode provided opposite each other in a chamber;
Using a device having a first high-frequency power supply for applying high-frequency power of the above frequency and a second high-frequency power supply for applying high-frequency power of 3 MHz or less to the first electrode, the second electrode A plasma of a processing gas containing fluorine is formed by forming a high-frequency electric field between the first and second electrodes while the substrate is supported on the substrate, and the plasma on the film on the substrate is plasma-etched by the plasma. An etching method, wherein plasma is formed by high-frequency power from the first high-frequency power supply,
A plasma etching method is provided, wherein the magnitude of the high-frequency power from the second high-frequency power source is controlled according to a film to be etched.

[0010] The present invention also provides a first and a second electrode provided in a chamber to face each other, and a first high-frequency power supply for applying a high-frequency power of a frequency of 100 MHz or more to the first electrode. Using a device having a second high-frequency power supply for applying a high-frequency power of a frequency of 3 MHz or less to the first electrode, while supporting the substrate on the second electrode, A plasma of a processing gas containing fluorine by forming a high-frequency electric field between the electrodes, and a plasma etching method for plasma-etching the multilayer film on the substrate by using the plasma. A plasma is formed by high-frequency power, and the magnitude of the high-frequency power from the second high-frequency power source is controlled according to each film constituting the multilayer film. To provide a Zuma etching method.

Further, the present invention provides a plasma generating first and second electrodes provided opposite to each other in a chamber, and a high-frequency power having a frequency of 100 MHz or more applied to the first electrodes. 1 high-frequency power supply, a second high-frequency power supply for applying high-frequency power of a frequency of 3 MHz or less to the first electrode, exhaust means for maintaining the inside of the chamber in a predetermined reduced pressure state, and fluorine in the chamber. A processing gas introducing means for introducing a processing gas to be contained, and a control means for controlling the magnitude of the high frequency power from the second high frequency power supply according to a film to be etched, wherein a substrate is provided on the second electrode. A plasma etching apparatus characterized by performing a plasma etching process on a film on a substrate while supporting the substrate.

Further, the present invention relates to an etching apparatus for etching a multilayer film on a substrate, comprising: a first electrode and a second electrode provided in a chamber facing each other; A first high-frequency power source for generating plasma, which applies high-frequency power of the above frequency; a second high-frequency power source, which applies high-frequency power of a frequency of 3 MHz or less to the first electrode; Exhaust means for maintaining a reduced pressure state, processing gas introduction means for introducing a processing gas containing fluorine into the chamber,
Detecting means for detecting a boundary of each film at the time of etching; and a film to be etched among the multilayer films is grasped based on information detected by the detecting means, and from the second high-frequency power supply according to the film. Control means for controlling the magnitude of the high-frequency power, and plasma etching is performed continuously on each film on the substrate while the substrate is supported by the second electrode. An etching apparatus is provided.

Hereinafter, the circumstances that led to the present invention will be described. A conventional capacitively-coupled plasma etching apparatus that forms a plasma by generating a high-frequency electric field between opposed electrodes generally supplies a high-frequency power of 13.56 to 60 MHz for plasma formation to an upper electrode. A plasma is generated by supplying a high frequency power of 800 kHz to 13.56 MHz for ion attraction to a lower electrode on which a substrate such as a semiconductor wafer is placed.

As shown in FIG. 1, generally, a plasma type
As the high-frequency power for production increases,
Pressure (self-bias voltage Vdc) increases and plasma density increases
(Electron density Ne) increases, but the high frequency applied to the electrode
Higher frequency to achieve the same plasma density
The required power is lower. Also, as shown in FIG.
The higher the frequency of the high frequency applied to the
The value of the pressure (Vdc) also decreases. The process used for etching
Plasma density region (Ne = 10⁹-10¹¹cm ^-3)
The voltage Vdc generated at the electrode to obtain
Number is 600-900V at 27MHz, 20 at 60MHz
0-400V.

C₄F₈And C₅F₈Using a gas like
Dissociation in plasma during oxide film etching process
CF_xRadicals polymerize after attaching to the electrode surface,
C_xF_yForm a polymer. High voltage generated at the electrode
The polymer is sputtered by ions
Deposits on semiconductor wafer. The deposited polymer is plasm
Even if dissociated in the original C₄F₈And C₅F₈Higher than
(High molecular weight) polymer with high adsorption coefficient
No. For this reason, it is mainly used for
Adhering to the opening and hindering resist etching
The resist selectivity is further improved. The voltage generated at the electrode
If it is low, C formed on the electrode surface_xF _yPolymer
Since it is not sputtered, polymer resist protection
Little effect and formation of deposits at the entrance of contact holes
No.

A case where a contact hole is formed in a multilayer film in which an oxide film and a nitride film are stacked will be described. As a gas system for etching the oxide film and the nitride film,
C ₄ F ₈ (or C ₅ F ₈ ) + O ₂ + Ar is used. In some cases, the etching of the nitride film is promoted by mixing a gas containing hydrogen such as CH ₂ F ₂ . Then, the oxide film and the nitride film are each formed of C generated in the plasma.
The following reactions (1) to (3) and reactions (4) to (6) occur with the F _x radical.

[0017] _{· 4CF 3 + 3SiO 2 → 3SiF} 4 ↑ + 4CO ↑ + O 2 ↑ ... (1) when the _{CF 2 4CF 2 + 2SiO 2 →} 2SiF 4 ↑ + 4CO ↑ ... (2) when in the case of the oxide film CF ₃ when the CF 4CF + SiO ₂ → SiF ₄ {+ 2CO} + 2C (3)

[0018] - If the nitride film when the _{CF 3 4CF 3 + Si 3 N} 4 + 4H → 3SiF 4 ↑ + 4HCN ↑ ... (4) 4CF 2 + (2/3) When the _{CF 2 Si 3 N 4 + (} 8/3 ) H → 2SiF ₄ ↑ + (8/3) H CN ↑ + (4/3) C (5) For CF 4CF + (1/3) Si ₃ N ₄ + (4/3) H → SiF ₄ ) + (4/3) HCN ↑ + (8/3) C… (6)

As is apparent from the above equation, when the dissociation energies are equal, the etching rate of the oxide film is three times the etching rate of the nitride film. The etching rate is higher when the F content of both the oxide film and the nitride film is larger (the amount of reacting Si is larger). Further, when carbon is deposited on both the oxide film and the nitride film, etching of holes is hindered, but the deposited carbon is removed by O ₂ . Further, when O ₂ is generated or F is large, the etching rate of the resist is high (in the case of the above formula (2)).

Now, as shown in FIG.
Consider a case in which a nitride film 102 and an oxide film 103 are sequentially laminated on 01 to form a multilayer film, and etching is performed using the resist 104 as a mask to form holes in the multilayer film.
In the first etching of the oxide film 103, the etching is usually performed under the condition that the selectivity with respect to the resist is high. However, when the nitride film 102 is etched under the condition, the etching rate is reduced because carbon is deposited, and the etching speed is reduced. As shown in the figure, the hole 105a has a tapered shape in the nitride film 102. When etching is performed under conditions (such as an increase in the flow rate of O ₂ ) to remove deposited carbon in order to eliminate such taper, the selectivity with respect to the resist decreases, and as shown in FIG. The resist 104 is largely etched to form a hole 105b having a wide frontage.

As shown in FIG. 4A, a third nitride film 112 and a third oxide film 11
3, a second nitride film 114, a second oxide film 115, a first nitride film 116, and a first oxide film 117 are sequentially stacked to form a multilayer film, and the multilayer is formed by etching using a resist 118 as a mask. In the case where holes are formed in the film, if etching is performed under conditions having a high selectivity with respect to the resist, the holes 119a become tapered in the first nitride film 116 as shown in FIG. Since the etching of the second oxide film 115 starts in a state where the etching in the lateral direction has not progressed, the second oxide film 115
Is isotropic, and the hole 119a has a swelling shape in the second oxide film 115. The same applies to the portion corresponding to the third oxide film 113. Such a phenomenon occurs because the etching rate of the nitride film is lower than the etching rate of the oxide film under the condition that the selectivity to the resist is high. When etching is performed under conditions capable of removing the deposited carbon in order to obtain a vertically shaped hole, as shown in FIG. 4C, the etching rate of the resist 118 is increased as in FIG. 3C. As a result, the hole 119b having a wide frontage is formed.

As described above, when holes are formed by plasma etching in a multilayer film in which an oxide film and a nitride film are laminated, it has been difficult to achieve both the selectivity to the resist and the shape.

That is, when etching an oxide film, a hole having a sufficient shape can be formed under the condition of a high selectivity with respect to a resist. However, in the case of a nitride film, the etching rate is low. Under such conditions, carbon is deposited and etching is hindered. Therefore, in order to etch the nitride film with good shape, it is necessary to perform etching under conditions where the etching rate of the resist is high so that such carbon deposition does not occur. turn into.

Therefore, in the present invention, as described above, the first high-frequency power supply is applied to the first electrode on which the substrate is not mounted.
Apply high-frequency power at a frequency of 0 MHz or more, apply high-frequency power at a frequency of 3 MHz or less from a second high-frequency power supply to this electrode, form plasma with high-frequency power from the first high-frequency power supply, and perform etching. The magnitude of the high frequency power from the second high frequency power supply is controlled according to the film to be formed.

Thus, the amount of the polymer formed on the electrode can be controlled by changing the value of the voltage Vdc generated at the electrode without changing the plasma density. An appropriate etching reaction can be caused to the film to be etched while keeping the film constant. Therefore, even with a multilayer film made of different materials, a hole having a high selectivity to the resist and a good shape can be formed.

Taking a multilayer film in which an oxide film and a nitride film are laminated as an example, when etching the oxide film, high-frequency power of a frequency of 3 MHz or less is applied from the second high-frequency power source to the first high-frequency power source. The self-bias voltage Vdc of the electrode is set to several hundred volts to perform etching with a high selectivity to the resist, the second high-frequency power supply is turned off in the nitride film, and the voltage Vdc of the first electrode is lowered to select the resist. Although the ratio is low, etching can be performed without causing carbon deposition, and good holes can be formed in the multilayer film.
When the nitride film is etched, the etching rate of the resist is high because the selectivity is low. However, since the nitride film is thin, the problem of widening the hole frontage does not occur.

[0027]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 5 is a sectional view schematically showing a plasma etching apparatus according to one embodiment of the present invention. The plasma etching apparatus 1 is configured as a capacitively coupled parallel plate etching apparatus in which electrode plates are vertically opposed to each other and one side is connected to a power supply for plasma formation.

The plasma etching apparatus 1 has a cylindrical chamber 2 made of aluminum whose surface is anodized (anodized), for example, and the chamber 2 is grounded for safety. A substantially columnar susceptor support 4 for mounting an object to be processed, for example, a semiconductor wafer (hereinafter, referred to as “wafer”) W is provided at the bottom of the chamber 2 via an insulating plate 3 made of ceramic or the like. And the susceptor support 4
Is provided with a susceptor 5 constituting a lower electrode. This susceptor 5 has a high-pass filter (HP
F) 6 is connected.

A coolant chamber 7 is provided inside the susceptor support 4. In the coolant chamber 7, a coolant such as liquid nitrogen is introduced via a coolant introduction pipe 8, and a coolant discharge pipe 9 is provided. The wafer W is discharged and circulated, and the cold heat is transferred to the wafer W via the susceptor 5, whereby the processing surface of the wafer W is controlled to a desired temperature.

The susceptor 5 is formed in a disk shape having a convex upper central portion, and an electrostatic chuck 11 having substantially the same shape as the wafer W is provided thereon. The electrostatic chuck 11 has an electrode 12 interposed between insulating materials. When a DC voltage of, for example, 1.5 kV is applied from a DC power supply 13 connected to the electrode 12, the electrostatic chuck 11 holds the wafer W by, for example, Coulomb force. Adsorb electrostatically.

The insulating plate 3, the susceptor support 4, the susceptor 5, and the electrostatic chuck 11
A heat transfer medium, for example, H
A gas passage 14 for supplying e-gas or the like is formed, and the cool heat of the susceptor 5 is transmitted to the wafer W via the heat transfer medium, so that the wafer W is maintained at a predetermined temperature.

An annular focus ring 15 is arranged on the peripheral edge of the upper end of the susceptor 5 so as to surround the wafer W mounted on the electrostatic chuck 11. The focus ring 15 is made of a conductive material such as silicon, so that the uniformity of etching is improved.

An upper electrode 21 is provided above the susceptor 5 so as to face the susceptor 5 in parallel. The upper electrode 21 is connected to the chamber 2 via an insulating material 25.
And an electrode plate 23 having a surface facing the susceptor 5 and having a large number of discharge holes 24, and a conductive material that supports the electrode plate 23, such as aluminum whose surface is anodized. And an electrode support 22 having a water cooling structure. The susceptor 5 serving as the lower electrode and the upper electrode 21 are, for example, 10 to 60 mm in length.
It is about a distance apart.

The electrode support 22 of the upper electrode 21
Is provided with a gas inlet 26, and a gas supply pipe 27 is connected to the gas inlet 26. The gas supply pipe 27 is further connected to a processing gas via a valve 28 and a mass flow controller 29. A source 30 is connected. A processing gas for etching is supplied from a processing gas supply source 30.

As a processing gas, a fluorine-containing gas is used. For example _C 4 _{F 8,} C 5 fluorocarbon gas such as _{F 8 (C} x _{F y)} and a hydrofluorocarbon gas such as _{CH 2 F 2 (C p H} q F r) can be suitably used.
Further, another gas such as O ₂ can be mixed. Further, a rare gas such as Ar or He or N ₂ can be added.

An exhaust pipe 31 is connected to the bottom of the chamber 2, and an exhaust device 35 is connected to the exhaust pipe 31. The exhaust device 35 is provided with a vacuum pump such as a turbo-molecular pump, so that the inside of the chamber 2 can be evacuated to a predetermined reduced-pressure atmosphere, for example, a predetermined pressure of 1 Pa or less. Further, a gate valve 32 is provided on a side wall of the chamber 2, and the wafer W is transferred to and from an adjacent load lock chamber (not shown) with the gate valve 32 opened. ing.

A first high frequency power supply 40 for plasma formation is connected to the upper electrode 21 via a matching unit 41 and a circulator 45. The circulator 45 is connected to a dummy load 46. The first high-frequency power supply 40 has a high frequency of 100 MHz or more, and a high-density plasma can be formed by applying such a high frequency. Further, by having a frequency of 100 MHz or more, the voltage (self-bias voltage Vdc) generated at the upper electrode 21 can be set to a low value of about several tens of volts. Although there is no particular upper limit of the frequency of the first high-frequency power supply 40,
The following is preferred. The circulator 45 functions as a kind of band-pass filter, and has an action of transmitting a frequency component reflected wave other than a specific frequency to the dummy load 46.

The upper electrode 21 is supplied with a 3 MHz signal through a low pass filter (LPF) 44 and a matching unit 43.
A second high frequency power supply 42 having the following frequency is connected. The second high frequency power supply 42 has a function of controlling the self-bias voltage Vdc generated in the upper electrode 21. Although there is no particular lower limit for the high-frequency power supply 42,
z or more is preferable.

A third high-frequency power supply 50 for attracting ions is connected to the susceptor 5 serving as a lower electrode.
A matching device 51 is interposed in the feed line. This third
High frequency power supply 50 is, for example, 800 kHz to 13.56 M
It has a frequency in the range of Hz, and by applying a frequency in such a range, an appropriate ion action can be given to the wafer W as a processing target without damaging it.

A window 60 for transmitting light from the plasma is formed on the side wall of the chamber 2 opposite to the gate valve 32 side. A spectroscope 61 and a spectroscope for splitting the plasma light transmitted from the window 60 are formed. An emission intensity detection device 62 for detecting the emission intensity of the light of the specific wavelength split at 61 is provided. The luminescence intensity detection device 62 can detect the luminescence intensity of the wavelength of each reaction product separated by the spectroscope 61.

A control unit 70 is provided, and a signal from the light emission intensity detection device 62 is input to the control unit 70. The control unit 70 grasps the boundary of the multilayer film formed on the wafer W and the end point of the etching based on the emission intensity of the wavelength of each reaction product detected by the emission intensity detection device 62. Then, the control unit 70 controls the magnitude of the high frequency power from the second high frequency power supply 42 based on the information, for example, performs on / off control. The control unit 70 also controls the first high-frequency power supply 40 and the third high-frequency power supply 50. These high-frequency powers are set to appropriate values at the time of etching, and the etching end point signal is also set. Is received, the first to third high frequency power supplies 40, 42, 50 are controlled to be turned off.

Next, the processing operation in the plasma etching apparatus 1 configured as described above will be described. First, after the gate valve 32 is opened, the wafer W to be processed is carried into the chamber 2 from a load lock chamber (not shown) and is placed on the electrostatic chuck 11.
The wafer W is electrostatically attracted onto the electrostatic chuck 11 by applying a DC voltage from the DC power supply 13. Next, the gate valve 32 is closed and the exhaust device 3
5, the inside of the chamber 2 is evacuated to a predetermined degree of vacuum.

Thereafter, the valve 28 is opened and the processing gas is supplied from the processing gas supply source 30 to the mass flow controller 2.
9, while the flow rate is adjusted, the processing gas supply pipe 2
7. The gas is introduced into the upper electrode 21 through the gas inlet 26, and is further uniformly discharged to the wafer W through the discharge holes 24 of the electrode plate 23 as shown by arrows in FIG.
The pressure in the chamber 2 is maintained at a predetermined value.

Then, the first high frequency power supplies 40 to 100
A high frequency of not less than MHz is applied to the upper electrode 21. As a result, a high-frequency electric field is generated between the upper electrode 21 and the susceptor 5 as the lower electrode, and the processing gas is dissociated into plasma, and the wafer W is subjected to an etching process by the plasma. On the other hand, the third high frequency power supply 50 applies a high frequency of 100 kHz to 10 MHz, for example, 2 MHz, to the susceptor 5 serving as a lower electrode. As a result, ions in the plasma are drawn into the susceptor 5 side,
Etching anisotropy is enhanced by ion assist.

In this case, the frequency of the high-frequency power applied to the upper electrode 21 from the first high-frequency power supply 40 is 100 M
Hz or higher, the magnitude of electric power for obtaining a plasma density region of 10 ⁹ to 10 ¹¹ cm ⁻³ used for etching is small. Therefore, the self-bias voltage Vdc generated in the upper electrode 21 is several tens V or less. The small, high-frequency power from the high-frequency power source 1 alone does not substantially produce the polymer deposition effect.

On the other hand, 3 MH from the second high frequency power supply 42
100 MHz by applying a frequency equal to or lower than z to the upper electrode 21
The voltage Vdc generated at the electrodes can be increased without changing the plasma density, and a polymer deposition effect can be generated.

As described above, the optimum etching conditions differ depending on the film. For example, when etching an oxide film, it is necessary to form a hole having a sufficient shape under a high selectivity condition at which a polymer deposition effect occurs. You can,
In the case of a nitride film, since the etching rate is low, carbon deposits under such conditions and the etching is hindered.If the nitride film is also to be etched with good shape, the resist is formed so that carbon deposition does not occur. It is necessary to perform etching under the condition that the etching rate is high, but in that case, the frontage of the hole becomes wide.

Therefore, in the present embodiment, in order to prevent such inconvenience, the control unit 70 grasps the boundary of the multilayer film based on the detection signal from the light emission intensity detection device 62, and based on the information, The control unit 70 controls the magnitude of the high-frequency power from the second high-frequency power supply 42 according to the film to be etched to control the polymer deposition effect.

As a result, the polymer deposition effect can be controlled by changing the value of the voltage Vdc generated at the upper electrode 21 without changing the plasma density, so that the plasma density during etching is kept constant. As it is, an appropriate etching reaction can be caused to the film to be etched. Therefore, even with a multilayer film made of different materials, a hole having a high selectivity to the resist and a good shape can be formed.

The control in this case will be described by taking a multilayer film in which a nitride film is formed on a wafer W and an oxide film is laminated thereon as an example. After the light is separated by the spectroscope 61, the light emission intensity detecting device 62 detects the CO light emission intensity and the CN light emission intensity as shown in FIG. That is, when CO (wavelength: 226 nm) is detected, it indicates that the oxide film is being etched, and CN is detected.
(Wavelength 387.2 nm) indicates that the nitride film is being etched.

When etching the oxide film for the first time,
As shown in FIG. 6, the first and third high-frequency power sources 40, 5
0 is turned on, and the second high frequency power supply 42 is also turned on.
To This allows 3M to be used for high frequencies above 100 MHz.
Hz or less is superimposed, and the self-bias of the upper electrode 21 is
When the ass voltage Vdc becomes several hundred volts, a polymer deposition effect occurs.
You. For this reason, etchant with high selectivity to resist
Is performed. At this time, the emission intensity detection device 62 uses C
O was detected, but C was found at the boundary between the oxide film and the nitride film.
O decreases, and CN is detected. This
The boundary between the oxide film and the nitride film is grasped. Control in this state
The unit 70 controls the second high frequency power supply 42 to be turned off.
I do. Thus, the second high frequency power supply 42 is
By turning off, the self-bias voltage of the upper electrode 21 is reduced.
Conditions under which the pressure Vdc decreases and the polymer deposition effect does not occur
Become. This results in low selectivity to resist, but
Etching under conditions that do not cause carbon deposition
From the oxide film to the nitride film while maintaining good shape.
Can be performed. At this time, select the nitride film
Resist is etched during low ratio etching
However, since the nitride film is usually thin,
Absent. In this way, etching is completed up to the nitride film,
When the Si surface is exposed, CF_xIs no longer consumed,
No emission of CO and CN was detected and CF_xIs detected
Will be issued. Therefore, CF _xLuminescence detection
Indicates the end point of etching, and over-
After the etching, the etching is completed.

Next, the result of actually etching the multilayer film shown in FIG. 4A will be described.

Here, the first high-frequency power supply for generating plasma has a frequency of 150 MHz, the second high-frequency power supply for adjusting the self-bias voltage Vdc of the upper electrode has a frequency of 400 kHz, and the high-frequency power for ion attraction. A power supply with a frequency of 2 MHz is used.
The output of the high-frequency power supply is 1500 W, the output of the third high-frequency power supply is 1300 W, and the second high-frequency power supply is switched between an on state and an off state for supplying 300 W of power according to the film. Processing gases include C ₅ F ₈ and CH ₂
Using F ₂ , O ₂ , and Ar, a total flow rate of 0.2 L / mi
n was introduced into the chamber, and the pressure in the chamber was set to 1.3.
It was set to 3 Pa. The diameter of the hole formed by etching is about 0.2 μm, and the gap between the electrodes is 17 m.
m. When performing the etching, the first and third high-frequency power supplies are always turned on, the second high-frequency power supply is also turned on when etching the oxide film, and the second high-frequency power supply is turned on when etching the nitride film. The etching was turned off. As a result, as shown in FIG. 7, the hole 119c having an extremely good shape could be formed without tapering of the nitride film and without widening of the frontage portion.

The present invention is not limited to the above embodiment, but can be variously modified. For example, as shown in FIG. 8, a temperature control device 8 such as a high-temperature chiller is provided on the upper electrode.
0, the electrode surface temperature of about 100 ° C.
The temperature may be controlled up to 00 ° C. Thus, at 100 ° C., the CF polymer deposited on the electrode can be heated at a higher temperature and deposited on the substrate to be processed, and the same function as the second high-frequency power supply can be achieved.

In the above embodiment, the case where the second high-frequency power supply is mainly turned on / off is described. However, the magnitude of the power of the second high-frequency power supply may be controlled. Furthermore, although a laminated film of an oxide film and a nitride film has been described as an example of the multilayer film, other films may be used. Furthermore, although the boundary between the films of the multilayer film is detected based on the emission intensity of the components in the plasma, the present invention is not limited to this, and other detection methods may be used. The etching time of each film may be grasped in advance, and the boundary of the film may be grasped by the time. In the above embodiment, a high frequency is applied to the upper and lower electrodes, but a type in which a high frequency is applied only to the upper electrode may be used. Also, a case has been described in which a semiconductor wafer is used as a substrate to be processed and an oxide film on the wafer is etched. However, the present invention is not limited to this. Can be. Further, the substrate to be processed is not limited to the wafer, and may be another substrate such as a liquid crystal display (LCD) substrate.

[0056]

As described above, according to the present invention,
The first electrode on which the substrate is not mounted is connected to the first
Apply high-frequency power at a frequency of 00 MHz or more, apply high-frequency power at a frequency of 3 MHz or less from a second high-frequency power supply to this electrode, form plasma with high-frequency power from the first high-frequency power supply, and perform etching. The magnitude of the high-frequency power from the second high-frequency power supply is controlled according to the film to be formed, thereby controlling the polymer deposition effect by changing the value of the voltage Vdc generated at the electrode without changing the plasma density. Therefore, it is possible to cause an appropriate etching reaction on the film to be etched while keeping the plasma density constant. Therefore, even with a multilayer film made of different materials, a hole having a high selectivity to the resist and a good shape can be formed.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the magnitude of high frequency power and electron density (Ne) for each frequency f of a high frequency power supply.

FIG. 2 is a diagram illustrating a relationship between a frequency f of a high-frequency power supply and a voltage Vdc generated at an electrode when Ne is constant.

FIG. 3 is a schematic view showing an example of forming a hole in a multilayer film by etching.

FIG. 4 is a schematic view showing another example when a hole is formed in a multilayer film by etching.

FIG. 5 is a sectional view schematically showing a plasma etching apparatus according to one embodiment of the present invention.

FIG. 6 is a timing chart showing a control example at the time of etching a multilayer film in the plasma etching apparatus according to one embodiment of the present invention.

FIG. 7 is a diagram showing a hole shape of a multilayer film formed according to an embodiment of the present invention.

FIG. 8 is a sectional view showing a main part of a plasma etching apparatus according to another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1; plasma etching apparatus 2: chamber 5; susceptor (second electrode) 21; upper electrode (first electrode) 30; processing gas supply source 40; first high-frequency power supply 42; Device 62; emission intensity detection device 70; control units 41, 43, 51; matching device W; semiconductor wafer

Continued on the front page F term (reference) 4K057 DA12 DA14 DA16 DB06 DB20 DD01 DD08 DE06 DE14 DE20 DJ03 DJ10 DM05 DM17 DM18 DN01 5F004 AA05 BA04 BA09 BB11 BB13 BB22 BB23 BB25 BB28 BB30 BB32 BC04 CA06 CB02 DA00 DA15 DA26 DB23 DA23 EA11 EB01

Claims (10)

[Claims] A first electrode and a second electrode provided in the chamber so as to face each other;
Using a device having a first high-frequency power supply for applying high-frequency power of the above frequency and a second high-frequency power supply for applying high-frequency power of 3 MHz or less to the first electrode, the second electrode A plasma of a processing gas containing fluorine is formed by forming a high-frequency electric field between the first and second electrodes while the substrate is supported on the substrate, and the plasma on the film on the substrate is plasma-etched by the plasma. An etching method, wherein plasma is formed by high-frequency power from the first high-frequency power source, and the magnitude of high-frequency power from the second high-frequency power source is controlled according to a film to be etched. Plasma etching method. 2. A first and a second electrode provided opposite each other in a chamber, and a 100 MHz
Using a device having a first high-frequency power supply for applying high-frequency power of the above frequency and a second high-frequency power supply for applying high-frequency power of 3 MHz or less to the first electrode, the second electrode A high-frequency electric field is formed between the first and second electrodes while the substrate is supported on the substrate to form a plasma of a processing gas containing fluorine, and the plasma is used to plasma-etch a multilayer film on the substrate. A plasma etching method, wherein plasma is formed by high-frequency power from the first high-frequency power source, and the magnitude of high-frequency power from the second high-frequency power source is controlled according to each film constituting a multilayer film. A plasma etching method characterized by the above-mentioned. 3. The plasma etching method according to claim 2, wherein boundaries between the respective films of the multilayer film are grasped by detecting plasma emission during etching. 4. The plasma etching method according to claim 2, wherein a boundary between the respective films of the multilayer film is grasped by a previously determined etching processing time of each film. 5. The plasma etching method according to claim 1, wherein the second high frequency power supply is turned on / off according to a film to be etched. 6. The plasma etching method according to claim 1, wherein the first electrode contains Si or C. 7. A first high-frequency power supply for generating plasma, comprising: first and second electrodes provided opposite to each other in a chamber; and high-frequency power having a frequency of 100 MHz or more applied to the first electrodes. A second high-frequency power supply for applying high-frequency power of a frequency of 3 MHz or less to the first electrode; an exhaust unit for maintaining the inside of the chamber at a predetermined reduced pressure; and a processing gas containing fluorine in the chamber. And a control means for controlling the magnitude of the high-frequency power from the second high-frequency power supply in accordance with the film to be etched, wherein the second electrode supports a substrate. A plasma etching apparatus, wherein a plasma etching process is performed on a film on a substrate in a state. 8. An etching apparatus for etching a multilayer film on a substrate, comprising: a first electrode and a second electrode provided in a chamber facing each other; A first high-frequency power source for applying power, for generating plasma; a second high-frequency power source for applying high-frequency power of a frequency of 3 MHz or less to the first electrode; and maintaining a predetermined reduced pressure in the chamber. Exhaust means, processing gas introducing means for introducing a processing gas containing fluorine into the chamber, detecting means for detecting a boundary of each film at the time of etching, and multilayer based on information detected by the detecting means. Control means for grasping a film to be etched among the films and controlling the magnitude of the high-frequency power from the second high-frequency power supply according to the film; While being supported substrate, plasma etching apparatus, characterized in that in succession the film on the substrate subjected to the plasma etching process. 9. The plasma etching apparatus according to claim 8, wherein said detection means detects light emission of plasma at the time of etching, and detects a boundary of the film based on a change of the light emission. 10. The frequency of 800 kHz to 1 is applied to the second electrode.
The plasma etching apparatus according to any one of claims 7 to 9, further comprising a third high frequency power supply for applying a high frequency power of 3.56 MHz.