JPH0992490A - Helicon-wave plasma device and plasma processing method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent local abnormalities in shape and unevenness of film thickness to enhance the accuracy and reliability of plasma processing by dispersing localized high-energy electrons in a bell jar using a dielectric buffer member having a tapered end. SOLUTION: A loop antenna 2 connected to a plasma-excitation RF power supply 11 is wound around a bell jar 1, and a solenoid coil 3 is provided outside it. A diffusion chamber 4 is connected to draw out a plasma P along a magnetic field diverging from the solenoid coil 3, so as to perform predetermined plasma processing on a wafer W on a stage 6. A bias-application RF power supply 14 is connected to the stage 6. Further, a ceramic ring 15 serving as a dielectric buffer member having a tapered end is placed inside the bell jar 1 to disperse localized high-energy electrons. Therefore, local abnormalities in the shape of a fine pattern and unevenness of film thickness that result from local charge accumulation are prevented to enhance the accuracy and reliability of the plasma processing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helicon wave plasma apparatus applied to the field of microfabrication such as semiconductor device manufacturing and a plasma processing method using the same, and in particular, it is generated in the radius r direction of a cylindrical container for exciting plasma. The present invention relates to a technique for reducing uneven distribution of high-energy electrons and performing highly uniform plasma etching or plasma CVD.

[0002]

2. Description of the Related Art In semiconductor devices such as VLSI and ULSI in recent years, the miniaturization of the minimum processing size, the increase of the chip area, the complication of the device structure and the circuit pattern are accelerated as the integration density and the density are increased. Therefore, further improvement in performance is also required for the plasma etching apparatus and the plasma CVD apparatus that are responsible for the processing and production.
For example, regarding plasma etching equipment, excellent shape anisotropy, high selectivity, reduction of dimensional conversion difference, practical etching rate, high etching uniformity for large-diameter substrates (wafers), low damage, It must be able to maximize the conflicting requirements of low pollution.

In order to improve these performances, some so-called high-density plasma devices, such as electron cyclotron resonance (ECR) plasma and inductively coupled plasma, which can achieve a plasma density on the order of 10 ¹¹ / cm ³ or more have been proposed. There is. Among such high-density plasma devices, one of the most promising devices is a helicon wave plasma device that excites plasma using a helicon wave. What is a helicon wave?
It is a kind of right-handed circularly polarized wave called Heusler that propagates in gas plasma, and differs from the electron cyclotron wave in that the cylindrical coordinate system is rotated in the θ direction according to the azimuth mode number m.

Although the helicon wave plasma excited by this helicon wave is characterized by an extremely high ionization rate,
For this, as a helicon wave attenuation mechanism by plasma,
This is because collision-free damping is involved in addition to collision damping.
In particular, Landa, which is a kind of collisionless damping, plays an important role in increasing the density of plasma.
u) It is considered to be damping. What is Landau damping?
This is a phenomenon in which the resonance electrons moving in the direction of the magnetic force line at a velocity almost equal to the phase velocity of the helicon wave continue to be accelerated in a direct current by the electric field created by the helicon wave, and as a result, the energy of the helicon wave is absorbed. Although there are both faster and slower electrons than the helicon wave in the plasma, the Maxwell distribution shows that the number of slower electrons is a little larger, and thus it is possible to absorb energy from such helicon waves. Since the high-energy electrons generated by such an energy absorption mechanism participate in the dissociation of gas molecules, the helicon wave plasma achieves a plasma density of the order of 10 ¹³ / cm ³ or more.

FIG. 8 shows the configuration of a general helicon wave plasma device. The plasma generation unit of this device includes a bell jar 31 which is a cylindrical container for generating helicon wave plasma P, and a loop wound around the bell jar 31.
The antenna 32 and a solenoid coil 33 that orbits the bell jar 31 further outside the loop antenna 32 and generates a magnetic field along the axis z direction are the main constituent elements. The bell jar 31 is made of a dielectric material such as quartz. Further, the loop antenna 32 is connected to a plasma excitation RF power source 41 via a matching network 40 so as to generate a helicon wave of m = 0 mode or m = 1 mode depending on the winding mode. Has been done.

Here, the electric field pattern in the m = 0 mode is purely electromagnetic at the phase angle ψ = 0. Phase angle ψ
= Π / 2 is a purely electrostatic radial pattern. An intermediate azimuth angle ψ shows an intermediate electromagnetic and electrostatic spiral pattern. Helicon wave plasma of m = 0 mode can be excited by a simple one-turn antenna. On the other hand, the m = 1 mode is always a mixture of an electromagnetic component and an electrostatic component, and its electric field pattern simply rotates in the clockwise direction with the propagation of the helicon wave. The helicon wave plasma of m = 1 mode uses a double loop type antenna,
It is excited by inductive coupling to a time-dependent magnetic field orthogonal to the electric field.

The bell jar 31 includes a diffusion chamber 34.
Is connected. This is the solenoid coil 3
3 is a processing chamber for drawing a helicon wave plasma P along a divergent magnetic field formed by 3 to perform a predetermined plasma processing on the wafer W on the stage 36 housed inside. The stage 36 is insulated from the wall surface of the diffusion chamber 34 by using an insulating member, and the legs thereof have a blocking capacitor 42 and a matching network 43 in between, and a bias application RF power source 4 is provided.
4 are connected. The gas required for plasma processing is supplied from the gas supply pipe 35 opened in the ceiling in the direction of arrow B after high-vacuum exhausting the inside of the diffusion chamber 34 through the exhaust hole 37 in the direction of arrow A by an exhaust system (not shown). It Further, a gate valve 38 is provided on the side wall surface of the diffusion chamber 34 so that the wafer W can be transferred to, for example, a load lock chamber or the like (not shown).

Further, outside the diffusion chamber 34, a divergent magnetic field in the vicinity of the stage 36 is converged, and in order to suppress the disappearance of electrons and active species in plasma by the chamber wall, a multi-purpose auxiliary magnetic field generating means is used. A pole magnet 39 is arranged.

Helicon wave plasma is superior in in-plane uniformity and reproducibility of plasma as compared with ECR plasma which requires a strong magnetic field for its generation. The present inventor has confirmed good characteristics of in-plane uniformity within ± 5% and inter-wafer uniformity within ± 5% in dry etching of an Al-based multilayer film on a 6-inch diameter wafer by a helicon wave plasma device. ing.

[0010]

By the way, although the uniformity of the helicon wave plasma is relatively superior to that of the ECR plasma as described above, further miniaturization of semiconductor devices and chip area There is still room for improvement in absolute uniformity when considering the large-diameter wafers that accompany expansion. For example, Proceedings of the 41st Joint Lecture on Applied Physics (Spring Annual Meeting 1994) p. 46, Abstract No. 31p-ZE-2, the spatial structure of the electron distribution of the m = 0 mode helicon wave plasma in the antenna region in the helicon wave plasma device by RF loop antenna excitation similar in basic configuration to the commercial device. The result of optical measurement of is reported. According to this study, m = 0
Concentric deviations are generated in the distribution of high-energy electrons in the cylindrical container in correlation with the morphology of the modal helicon wave.

FIG. 9 is a view for conceptually explaining uneven distribution of high-energy electrons in the m = 0 mode.
The figure (a) shows the high-energy electron density distribution in the direction of the radius of the bell jar, and the colored portion shows the electron temperature Te.
Shows a distribution maximum region larger than 10 eV. This bias is preserved almost as it is even when the plasma is transported as a flux from the plasma source toward the wafer surface by the diffusion magnetic field. FIG. 6B is a graph showing this state. When the normalized saturated electron current density is plotted along the wafer diameter, a peak corresponding to the donut-shaped distribution maximum region in FIG.

On the other hand, FIG. 10 is a diagram showing uneven distribution of high-energy electrons similarly in the m = 1 mode. m = 1
In the case of the mode, the electron density becomes high in the region centered on the axis z of the bell jar.

Regardless of which mode is adopted, the uneven distribution of high-energy electrons causes inconvenience in plasma processing. This problem will be described with reference to FIG. 11 by taking dry etching of an Al-based multilayer film as an example.

FIG. 11 shows the S formed on the Si substrate 51.
A resist mask 57 is formed on the iOx interlayer insulating film 52.
It shows a state in which the Al-based wiring pattern 56 is formed by dry etching using (PR). Here, the Al-based wiring pattern 56 is a TiN barrier metal pattern 53n (subscript n represents a notching shape) and an Al-1% Si pattern 54a in order from the lower layer side.
(The subscript a indicates that it has an anisotropic shape.), TiN
The antireflection film pattern 55a is laminated.

Here, the notch shape called notching is formed in the TiN barrier metal pattern 53n because the bias of high energy electrons in the helicon wave plasma causes local charge accumulation on the wafer. This is because the orbits of the ions bend and the ion assist mechanism does not work perpendicularly to the wafer surface. That is, when the TiN antireflection film or the Al-1% Si film is etched, since the conductive film having a sufficient thickness exists in the region to be etched, charge accumulation on the wafer is not so problematic. These films are relatively easy to be anisotropically processed. However, at the time of etching the TiN barrier metal, a sufficient amount of the conductive film does not exist in the region to be etched and the underlying layer is the SiOx interlayer insulating film 52, so that the charges accumulated on the wafer surface are less likely to leak, resulting in In addition, the ion trajectory of the ions near the wafer is bent. Therefore, the ion assist mechanism also works from the side wall surface of the pattern, causing notching in the TiN barrier metal pattern 53n.

Problems caused by accumulated charges also occur in CVD. In the case of CVD, the incident orbit of the deposited species and the ion orbit of the ions responsible for the flattening effect are bent, which causes inconvenience, for example, that the space between the wirings is not sufficiently filled with the insulating film and a void is generated.

Conventionally, in order to deal with the notching and the nonuniformity of the film thickness, the gradient of the diffusion magnetic field, the magnetic flux density, or the power supplied to the loop antenna has been optimized. From the perspective of plasma margin
It was not always easy. Therefore, the present invention is proposed in view of such conventional problems, and when dry etching or CVD is performed on a large-diameter wafer, it is excellent in basic characteristics and low damage, and is particularly caused by local charge accumulation or the like. It is an object of the present invention to propose a helicon wave plasma device capable of preventing such abnormal shape and a plasma processing method using the same.

[0018]

According to the present invention, an induction electric field component E and an induction magnetic field component B respectively correspond to a radius r direction, an axis z direction and an azimuth angle θ direction of a cylindrical container of a helicon wave plasma device. In order to reduce the local density difference of high-energy electrons generated in the cylindrical container according to the wave form of the helicon wave and the collisional damping and the collisionless damping of the helicon wave, a dielectric buffer member is provided in the cylindrical container. To disperse the localized high-energy electrons.

The shape of the buffer member is a virtual line perpendicular to the axis z of the cylindrical container so that the electric field component E and the magnetic field component B in the direction of the axis z are not hindered and the mode of the helicon wave is not changed. The shape is such that its cross-sectional area in the plane increases monotonically over at least a part of the axis z direction. Also,
The buffer member is installed in such a manner that the tip end portion of which the above-mentioned cross-sectional area is minimum is made to substantially coincide with the center of the maximum distribution region of high-energy electrons in the radius r direction of the cylindrical container. This effectively disperses the localization of high-energy electrons.

By the way, since the distribution of high-energy electrons in the radius r direction of the cylindrical container differs depending on the propagation mode of the helicon wave, it is necessary to select the optimum shape of the buffer member according to this. For example, if the propagation mode is m =
In the 0 mode, high-energy electrons are localized concentrically around the axis z.
A buffer member having an annular cross section in an imaginary plane perpendicular to the axis z is used.

In the case of m = 1 mode, a localized region is generated on the axis z.
A cushioning member having a circular cross-sectional shape on an imaginary plane perpendicular to is arranged at the center of the cylindrical container. That is, in the case of m = 1 mode, at least a conical cushioning member having a tip end portion is arranged in alignment with the axis z.

Whichever mode is adopted, thereafter, by operating this helicon wave plasma device in the same manner as usual, various plasma treatments can be performed while improving the high energy electron distribution.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a cylindrical coordinate system, an induced electric field component in the radius r direction is Er, an induced electric field component in the azimuth angle θ direction is Eθ, an induced electric field component in the axis z direction is Ez, and an induced magnetic field component in the radius r direction. Is Br, and the induced magnetic field component in the azimuth angle θ direction is B
When the induced magnetic field component in the θ direction and the axis z direction is defined as Bz, the wave form of the helicon wave is expressed by the following equations [1] to [3].

[0024]

[Equation 1]

[0025] Here, k is a helicon wave of wave number, omega is helicon wave angular frequency, A is a constant, T is the orthogonal wave number, m is the azimuthal mode number, J _m (Tr) is the Bessel function, J _'m ( Tr) is the derivative, ω _p is the electron plasma frequency, ω _c is the electron cyclotron frequency, and c is the speed of light.

Here, in the case of m = 0 mode, the following equation [4]

[0027]

[Equation 2]

From the regression relational expression shown by J ₋₁ = −J ₁ ,
And J ′ ₀ = −TJ ₁ , the equations [1] to [3] are transformed into the following equations [5] to [7], respectively.

[0029]

(Equation 3)

Here, when r = a (radius) and the boundary condition is J ₁ (Ta) = 0, the root T of the smallest radiation mode number is
a becomes 3.83 regardless of the value of k / α. Br and B
Both θ are maximum at the point of r / a = 1.84 / 3.83.

On the other hand, in the m = 1 mode, equations [1] to
[3] can be rewritten as the following expressions [8] to [10].

[0032]

[Equation 4]

Here, J ₁ = (Tr / 2m) (J ₀ + J ₂ ), and J ′ ₁ from the regression relational expression represented by the above-mentioned formula [4].
= (T / 2) (J ₀ −J ₂ ), equations [8] and [9]
Can be further written as the following equations [11] and [12].

[0034]

(Equation 5)

In the m = 1 mode, the electric field pattern is m = 0.
Unlike the case of the mode, it changes according to the value of k / α. The value of T for each value of k / α is determined as the solution of equation [12]. That is, it is obtained by solving the following equation [13].

[0036]

(Equation 6)

The point r ₀ on the radius where the electric field lines of the m = 1 mode are focused can be obtained as the solution of the equation [11].
That is, it can be obtained by solving the following equation [14].

[0038]

(Equation 7)

Wave energy absorption varies with J _m (Tr).

The density distribution of high-energy electrons in the helicon wave plasma is brought about by the collision damping and the collisionless damping in the presence of the induced electric field component E and the induced magnetic field component B as described above. In the present invention, the localization of high-energy electrons is dispersed by placing a buffer member made of a dielectric material in the cylindrical container. As a specific embodiment of the present invention, a configuration example of a helicon wave plasma device and dry etching of an Al-based wiring film using the same will be described below.

First Embodiment Here, a plasma apparatus for exciting helicon wave plasma of m = 0 mode will be described with reference to FIG.

The plasma generating unit of this apparatus includes a bell jar 1 which is a cylindrical container for generating helicon wave plasma P, a one-turn loop antenna 2 wound around the bell jar 1, and the one-turn loop. The main component is a solenoid coil 3 that orbits the bell jar 1 outside the antenna 2 and generates a magnetic field along the axis z direction. The bell jar 1 is made of a dielectric material such as quartz. In addition, the loop antenna 2 is a plasma excitation RF power source 1 via a matching network 10.
1 connected. Here, the frequency of the RF power source 11 for plasma excitation was 13.56 MHz.

A diffusion chamber 4 is connected to the bell jar 1. This is a processing chamber for performing a predetermined plasma processing on the wafer W on the stage 6 housed inside by drawing out the helicon wave plasma P along the divergent magnetic field formed by the solenoid coil 3. Is.

The stage 6 is insulated from the wall surface of the diffusion chamber 4 by using an insulating member. In addition, an electrostatic chuck mechanism (not shown), a cooling mechanism (for etching) or a heating mechanism (for CVD), and a cooling gas flow path are appropriately provided. An RF power supply 14 for bias application is connected to the legs of the stage 6 via a blocking capacitor 12 and a matching network 13. The gas required for plasma processing is the diffusion chamber 4
After high-vacuum-exhausting the inside of the chamber in the direction of arrow A through an exhaust hole 7 by an exhaust system (not shown), the gas is supplied in the direction of arrow B from a gas supply pipe 5 opened at the ceiling. Further, a gate valve 8 is provided on the side wall surface of the diffusion chamber 4 so that the wafer W can be transferred to, for example, a load lock chamber or the like (not shown).

Further, outside the diffusion chamber 4,
In order to converge the divergent magnetic field in the vicinity of the stage 6 and to suppress the disappearance of electrons and active species in the plasma by the chamber wall, a multi-pole magnet 9 is provided as an auxiliary magnetic field generating means. The multi-pole magnet 9 generates a multi-cusp magnetic field in the diffusion chamber 4 to confine plasma. The arrangement position of the multi-pole magnet 9 is not limited to the example shown in the figure, and may be another place such as around the support of the wafer stage 6. Further alternatively, this may be replaced by a solenoid coil, and the plasma may be confined by forming a mirror magnetic field.

The helicon wave plasma apparatus of the present invention is characterized by the ceramic ring 15 disposed inside the bell jar 1 in addition to the conventional general structure. This ceramic ring 15 is shown in FIG.
Here, FIG. 10A is a sectional view taken along line XX in FIG. 11B, that is, a sectional view taken along a virtual plane including the axis z. The ceramic ring 15 is not a simple circular pipe shape, but has a constant apex angle p from the tip portion 15t to the middle in the axis z direction.
It has a cross-sectional shape taken along the line X-X. The apex angle p may be selected within a range of up to about 30 °. Therefore, the sectional shape of the ceramic ring 15 in an imaginary plane perpendicular to the axis z is annular, but the sectional area at this time monotonically increases over at least part of the axis z direction.

Further, in the present invention, the disposition position of the ceramic ring 15 is important. That is, the tip portion 15t is arranged so as to substantially coincide with the center of the distribution maximum region of high energy electrons in the radius r direction of the bell jar 1. That is, in the above-mentioned FIG. 9A, the tip portion 15t is made to substantially coincide with the center line (shown by a broken line) of the colored portion representing the region of the electron temperature Te> 10 eV. Such an arrangement position is determined by adjusting the height of the support member 16 attached to the lower side wall surface of the ceramic ring 15. The end of the support member 16 is fixed to the ceiling of the diffusion chamber 4.

FIG. 3 shows plasma characteristics realized in the helicon wave plasma device of the present invention in which the ceramic ring 15 is arranged as described above. (A) The figure shows Belja 1
Is the high energy electron density distribution inside. Compared with the above-mentioned FIG. 9A, the maximum density regions are dispersed in the radius r direction. Further, FIG. (B) is a graph in which the normalized saturated electron current density is plotted along the wafer diameter,
A comparison with the above-mentioned FIG. 9B shows that the plasma density in the vicinity of the surface of the wafer W is more uniform.

Second Embodiment Next, as another embodiment of the present invention, a dielectric buffer member used in a plasma device for exciting helicon wave plasma of m = 1 mode will be described.

This m = 1 mode cushioning member is a ceramic cone 17 as shown in FIG. here,
FIG. 13A is a sectional view taken along line XX in FIG. 19B, that is, a sectional view taken along a virtual plane including the axis z. This ceramic cone 17 is formed by sharpening the tip of a circular rod into a conical shape. That is, the cross-sectional shape of the X-X line is the tip portion 17
The shape is such that it extends with a constant apex angle q from t to the middle of the axis z direction. This apex angle q may be selected within a range of up to about 30 °. Therefore, the cross-sectional shape of an imaginary plane perpendicular to the axis z of the ceramic cone 17 is circular, but the cross-sectional area at this time is the axis z.
Monotonically increasing over at least part of the direction.

The ceramic cone 17 is arranged so that its tip portion 17t substantially coincides with the center of the maximum distribution area of high-energy electrons of m = 1 mode plasma. That is, in the above-mentioned FIG. 10A, at the center O of the colored portion representing the region where the electron temperature Te> 10 eV,
The tip portion 17t is substantially matched. Although an overall view of the helicon wave plasma device in which the ceramic cone 17 is arranged is omitted, the ceramic cone 17 is replaced with the ceramic ring 15 in FIG. It is fixed to the section.

FIG. 5 shows the plasma characteristics obtained in the helicon wave plasma apparatus of the present invention in which the ceramic cone 17 as described above is arranged. (A) is a high energy electron density distribution in the bell jar 1. Compared with the above-mentioned FIG. 10A, the plasma density in the vicinity of the center O of the bell jar 1 is relaxed, and the maximum density regions are dispersed in a donut shape. Further, FIG. 10B is a graph in which the normalized saturated electron current density is plotted along the wafer diameter. Compared with FIG. 10B described above, the plasma density near the surface of the wafer W is higher. It is clear that they are homogenized.

Although the two embodiments of the present invention have been described above, the details of the apparatus configuration can be changed as appropriate.
For example, although the ceramic ring 15 and the ceramic cone 17 described above are both single members, the dielectric cushioning member used in the present invention may be configured by combining a plurality of members. For example, if ceramic rings with different diameters are arranged concentrically with each other, the high-density plasma region dispersed by one ring will be dispersed by another ring, and so on. A distribution can be achieved. The same effect can be obtained by arranging the ceramic ring as if it goes around the ceramic cone.

Further, even if it functions as a single buffer member as a whole, it is composed of a plurality of units divided in shape, and the positional relationship of each unit is changed by using the driving means. Thus, for example, a ring-shaped cushioning member that can expand and contract in the radius r direction of the cylindrical container can be obtained. With such a cushioning member, the dimensions can be finely adjusted according to the plasma conditions, so that the plasma density can be made more precise.

In addition, the number and shape of the supporting members can be appropriately changed and selected as long as the induced electric field component E and the induced magnetic field component B are not changed.

[0056]

EXAMPLE Here, the Al-based multilayer film was dry-etched using the helicon wave plasma apparatus of FIG. 1 in which a ceramic ring 15 for m = 0 mode plasma was arranged. This process will be described with reference to FIGS. 6 and 7.

The structure of the sample wafer used in this example is shown in FIG. This figure shows SiOx on the Si substrate 21.
The interlayer insulating film 22 and the Al-based multilayer film 26 are sequentially stacked, and the resist mask 27 is further formed on the Al-based multilayer film 26.
The state where (PR) is patterned is shown. Here, the Al-based multilayer film 26 is formed by laminating a TiN barrier metal 23, an Al-1% Si film 24, and a TiN antireflection film 25 in this order from the lower layer side. The resist mask 27 is formed into a line-and-space pattern of 0.25 .mu.m through KrF excimer laser lithography and development processing using, for example, a chemically amplified photoresist material.

The wafer in this state was set in the helicon wave plasma device shown in FIG. However, the diameter of bell jar 1 is 6
cm, the length in the axis z direction is 20 cm, the diameter of the tip portion 15t of the ceramic ring 15 is 2.9 cm, and the apex angle p is 20.
It was ゜. The frequency of the RF power source 11 for plasma excitation connected to the one-turn loop antenna 2 is 13.56 MH.
z. The etching conditions are, for example, BCl ₃ flow rate 30 SCCM Cl ₂ flow rate 60 SCCM pressure 0.7 Pa antenna supply power 2000 W (13.56 MHz) solenoid coil supply power 45 A RF bias power 140 W (2 MHz) wafer temperature 40 The backside He gas pressure was 800 Pa, and the electrostatic chuck supply power was -300 W.

By this etching, as shown in FIG. 7, the Al-based wiring pattern 2 having a good anisotropic shape is formed.
6a was formed. Here, in FIG. 7, each material film pattern formed by anisotropic etching is represented by adding the subscript a to the original code. This anisotropic shape was obtained almost uniformly over the entire surface of the wafer W. On the other hand, when the ceramic ring 15 is removed and etching is performed under the same conditions, as shown in FIG.
Notching shape occurred in the barrier metal pattern.

The specific embodiments of the present invention have been described above. However, in the present invention, not only the above Al-based multilayer film but also
A wiring film in which a conventionally known wiring material such as a polysilicon film, a polycide film, a silicide film, a refractory metal film, a Cu film, an Ag film, or an Au film is combined with a conventionally known barrier metal or an antireflection film, if necessary. Can etch an insulating film or an organic film. The plasma device of the present invention can also be used for CVD and plasma surface treatment.

[0061]

As is apparent from the above description, when the present invention is applied, the local shape anomaly of the fine pattern formed on the wafer whose diameter is increasing and the deposition accumulated on the wafer as well. The unevenness of the film thickness can be easily eliminated without performing any complicated control or a large capital investment. Therefore, the present invention greatly contributes to miniaturization, high performance, and high reliability of semiconductor devices by improving the accuracy of plasma processing.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a configuration example of a helicon wave plasma device (for m = 0 mode) of the present invention.

FIG. 2 is a diagram showing a ceramic ring (for m = 0 mode) used in the helicon wave plasma device of the present invention,
FIG. 7A is a sectional view taken along line XX in FIG. 7B, and FIG.

FIG. 3 is a diagram for explaining plasma characteristics in the m = 0 mode plasma of the present invention, wherein FIG. 3 (a) is a schematic diagram showing a high energy electron density distribution dispersed in a radius r direction of a bell jar; The graph b) is a graph showing the saturated electron current density distribution in the wafer radial direction.

FIG. 4 is a diagram showing a ceramic cone (for m = 1 mode) used in the helicon wave plasma device of the present invention,
FIG. 7A is a sectional view taken along line XX in FIG. 7B, and FIG.

FIG. 5 is a diagram for explaining plasma characteristics in m = 1 mode plasma of the present invention, wherein FIG. 5 (a) is a schematic diagram showing a high energy electron density distribution dispersed in a radius r direction of a bell jar; The graph b) is a graph showing the saturated electron current density distribution in the wafer radial direction.

FIG. 6 is a schematic cross-sectional view showing a state of a wafer before etching in dry etching of an Al-based multilayer film to which the present invention is applied.

7 is a schematic cross-sectional view showing a state where the Al-based multilayer film of FIG. 6 is anisotropically etched.

FIG. 8 is a schematic cross-sectional view showing a configuration example of a conventional helicon wave plasma device.

9A and 9B are diagrams for explaining plasma characteristics in a conventional m = 0 mode plasma, where FIG. 9A is a schematic diagram showing a high energy electron density distribution in a radius r direction of a bell jar, and FIG. It is a graph showing a saturated electron current density distribution in the wafer radial direction.

10A and 10B are diagrams for explaining plasma characteristics in a conventional m = 1 mode plasma, where FIG. 10A is a schematic diagram showing a high energy electron density distribution in a radius r direction of a bell jar, and FIG. It is a graph showing a saturated electron current density distribution in the wafer radial direction.

FIG. 11 is a schematic cross-sectional view showing a state in which a notching shape is generated in a TiN barrier metal in dry etching of an Al-based multilayer film using conventional helicon wave plasma.

[Explanation of symbols]

 1 Belger 2 1-turn loop antenna 3 Solenoid coil 4 Diffusion chamber 6 Wafer stage 11 RF power supply for plasma excitation 14 RF power supply for bias application 15 Ceramic ring 15t (ceramic ring 15) tip 17 Ceramic cone 17t Tip part (of ceramic cone 17) 16,18 Supporting member 22 SiOx interlayer insulating film 26 Al-based multilayer film 26a Al-based wiring pattern 27 Resist mask W Wafer P Helicon wave plasma

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H01L 21/3065 H01L 21/302 B

Claims (5)

[Claims] 1. A helicon wave plasma apparatus for exciting plasma using a helicon wave in a cylindrical container, wherein an induction electric field component E and an induction electric field component E respectively corresponding to a radius r direction, an axis z direction and an azimuth angle θ direction of the cylindrical container. In order to reduce the local density difference of high-energy electrons generated in the cylindrical container according to the wave form of the helicon wave represented by the magnetic field component B and the collisional damping and collisionless damping of the helicon wave, the cylindrical container A helicon wave plasma device in which a buffer member made of a dielectric material is arranged. 2. The buffer member has a shape such that its cross-sectional area in an imaginary plane perpendicular to the axis z of the cylindrical container increases monotonically over at least a part of the axis z direction, and the cross-sectional area is minimized. 2. The helicon wave plasma device according to claim 1, wherein the tip end portion of the helicon wave plasma device is arranged so as to substantially coincide with the center of the maximum distribution region of high-energy electrons in the radius r direction of the cylindrical container. 3. The helicon wave plasma according to claim 2, wherein a propagation mode of the helicon wave is an m = 0 mode, and a cross-sectional shape of the buffer member on an imaginary plane perpendicular to the axis z of the cylindrical container is an annular shape. apparatus. 4. The helicon wave plasma according to claim 2, wherein a propagation mode of the helicon wave is m = 1 mode, and a cross-sectional shape of the buffer member on an imaginary plane perpendicular to the axis z of the cylindrical container is circular. apparatus. 5. A plasma processing method for performing a predetermined plasma processing on a substrate held in a cylindrical container by using plasma excited by a helicon wave in the cylindrical container, the radius r of the cylindrical container. Direction, axis z direction and azimuth angle θ direction respectively, the wave form of the helicon wave expressed by the induced electric field component E and the induced magnetic field component B, and the collision damping and non-collision damping of the helicon wave in the cylindrical container A plasma processing method in which the predetermined plasma processing is performed while reducing the local density difference of high-energy electrons generated in the above by using a buffer member made of a dielectric material.