JPH08288259A - Helicon wave plasma device and dry etching method using the same - Google Patents

Abstract

(57) [Abstract] [Purpose] Dry etching with high in-plane uniformity even for large diameter wafers by freely controlling the dissociation state of etching gas and ion current density distribution in the chamber in a helicon wave plasma device. . [Structure] A single loop antenna 6 for m = 0 mode plasma excitation facing a top plate 2 of a plasma generation chamber 1, and a m = 1 mode half turn for plasma excitation that circulates a side wall of the chamber. The antenna 7 is provided, and either the normal high frequency power source 13 or the pulse power source 14 is connected to the both antennas 6 and 7 by operating the switch 12, and the two modes are adjusted while adjusting the respective outputs by the drive amplifiers 62 and 72. Simultaneous continuous generation or the same time-interrupted generation of the helicon wave plasma P _H is performed. [Effect] The increase in the etching rate of the Al-based wiring film around the wafer can be suppressed, so that the film loss of the base insulating film can be made uniform.

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 device and a dry etching method using the same, and more particularly to an etching rate for a large-diameter wafer by generating a high-density plasma having a uniform ion density. The present invention relates to an apparatus and a method capable of achieving excellent in-plane uniformity with respect to both the undercoat residual film thickness.

[0002]

2. Description of the Related Art In the field of semiconductor device manufacturing, high miniaturization and
High integration has been accelerated year by year, and at the research level, room temperature operation of a transistor with a gate length of 0.1 μm has been confirmed. Under such circumstances, the demand for microfabrication technology for manufacturing semiconductor devices is becoming more and more severe.

Dry etching using plasma generated by low-pressure gas discharge is an essential technique for such fine processing. When the design rules of semiconductor devices are miniaturized from sub-half micron to quarter micron or more, high speed is required for dry etching because wafers are premised on single-wafer processing. High selectivity and low damage are required because the constituent material films are thin, and high anisotropy is required because the dimension conversion difference from the resist mask is not allowed. It is also necessary to suppress the generation of particles and particle contamination. Here, in order to achieve high speed, high anisotropy, and low microloading, dry etching conditions in which radicality is weakened and ionicity is strengthened are advantageous. On the other hand, high selectivity, low damage,
In order to reduce pollution, dry etching conditions in which the radical property is strengthened and the ionic property is weakened are advantageous. However, these two conditions are mutually contradictory conditions, and it is extremely difficult to set dry etching conditions that can satisfy all of the above requirements at a practical level.

The optimization of such dry etching conditions is as follows.
Normally, this is done by selecting the type of etching gas, the gas pressure, and the substrate bias, but in recent years, 10 ¹¹ / cm
Several high-density plasma sources have been proposed one after another with ion densities of ³ or more, and the selection of the source is also an important factor.

Among such high-density plasma sources, a promising one is the helicon wave plasma described in Japanese Patent Laid-Open No. 3-68773. The generation mechanism applies a magnetic field to a cylindrical chamber and further applies a high frequency wave to a loop antenna wound around the chamber to generate a helicon wave in the chamber, and a process of Landau attenuation from the helicon wave. The energy is transferred to the electrons through to accelerate the electrons, and the electrons collide with gas molecules to obtain a high ionization rate. The helicon wave plasma device can achieve an ion density of 10 ¹¹ to 10 ¹³ / cm ³ (16 to 20 mA / cm ² in ion current density) under a low pressure of the order of 10 ⁻⁴ Pa. The plasma obtained at this time is considered to be in a substantially completely dissociated state.

Moreover, the helicon wave has a characteristic that it can propagate in a relatively wide RF frequency region between the ion cyclotron frequency ω _ci and the electron cyclotron frequency ω _ce , and the resonance condition is limited in this respect. This is advantageous as compared with ECR (electron cyclotron resonance) discharge in which electron heating is performed only in a region.

[0007]

By the way, in the manufacturing of semiconductor devices in recent years, the demand for dry etching has become strict as described above, so that the single wafer processing must be performed in order to ensure the uniformity of the processing. I don't get it. Moreover, since the area of one semiconductor chip tends to increase with higher integration, considering the economy and throughput, a large-diameter wafer is used so that the number of chips that can be cut out from one wafer increases. It becomes essential to use.

However, the increase in the diameter has a relationship between the front and back sides of the deterioration of in-plane uniformity of etching. For example, in the case of dry etching of Al-based wiring, since this etching proceeds mainly in the radical mode, the etching rate becomes higher in the peripheral portion of the wafer where the reaction product exhaust rate is higher due to the exhaust flow in the chamber. That is, the just etching of the Al-based material film ends earlier in the peripheral portion of the wafer. On the other hand, the underlying material film during dry etching of Al-based wiring is usually an insulating film such as a SiO ₂ film. The etching of this insulating film proceeds mainly in the ion mode, but the ion incident energy at this time is controlled by the substrate bias control in a remote plasma type device such as a helicon wave plasma device, so that the etching rate In-plane uniformity is relatively excellent. Then, the over-etching is additionally performed in the peripheral portion of the wafer where the Al-based material film has been removed earlier, and as a result, the residual film thickness of the underlying insulating film becomes uneven. In other words, etching
It is extremely difficult to achieve both the etching uniformity and the remaining film thickness uniformity at a satisfactory level for the Al-based material film and the underlying insulating film that have essentially different modes.

Therefore, it is considered effective to change the dissociation state of the etching gas and the saturated ion current density during just etching and during overetching, for example, but the conventional helicon wave plasma device finely responds to such a demand. I can't. This is related to the mode of the excited helicon wave.

In the free space, the helicon wave is a purely electromagnetic wave that is circularly polarized in the right-hand direction. However, in a limited space such as the plasma generation chamber, only a specific mode is excited and the electrostatic property is also generated. It becomes a prepared wave. Deduced from the linearization of the field equation, there is an electric field pattern as shown in Figure 1 as the first two modes. Here, the figure of (a) is m
= 0 mode, the figure in (b) represents m = 1 mode, and the value of m corresponds to the Bessel function that appears in the expression of electric field amplification. In the series of patterns, the pattern displayed in the center corresponds to the phase angle φ = 0, the upper end corresponds to the phase angle φ = π / 2, and the lower end corresponds to the phase angle φ = −π / 2. In the m = 0 mode, the wave spatially transitions from a completely electromagnetic state at phase angle = 0 to a completely electrostatic state at phase angle = π / 2. The electric field is helical between both states, and the waves are both electromagnetic and electrostatic in nature.

On the other hand, the m = 1 mode is always a mixture of an electromagnetic component and an electrostatic component, and the electric field pattern simply rotates in the clockwise direction as the wave propagates.

It is known that the propagation mode of the above-mentioned helicon wave plasma is changed by the winding mode of the antenna outside the plasma generation chamber, and this mode also changes the saturated ion current density distribution in the plasma generation chamber. . The state of this change is shown in FIG. In the figure,
The horizontal axis represents the position in the diameter direction of the plasma generation chamber (mm)
And the vertical axis represents the saturated ion current density (mA / cm ² ). As can be seen from this figure, in the m = 0 mode, the saturated ion current density shows a distribution in which it falls near the center of the chamber and becomes higher around it. On the other hand, the m = 1 mode shows a pattern having a peak in a relatively narrow range in the center of the chamber.

In a conventional helicon wave plasma device, m =
It is designed to excite helicon wave plasma in either 0 or m = 1 mode, so that even if either mode is excited, a uniform ion current density is achieved over the entire diameter of the chamber. It is difficult.
Further, it is impossible to change the saturated ion current density during the etching.

The present invention solves the above-mentioned problems,
An object of the present invention is to provide a helicon wave plasma device capable of freely changing the dissociation state of the etching gas and the ion current density, and a dry etching method capable of performing uniform etching using the device. .

[0015]

A helicon wave plasma device of the present invention is proposed to achieve the above-mentioned object, and is provided in a plasma generating chamber made of a dielectric material and in the inside of the plasma generating chamber. A first antenna for exciting helicon wave plasma of m = 0 mode, a second antenna for exciting helicon wave plasma of m = 1 mode inside the plasma generation chamber, and the first antenna And a high-frequency power supply means for supplying high-frequency power to the second antenna, a magnetic field generation means for orbiting the plasma generation chamber to generate a magnetic field therein, and connected to the plasma generation chamber and housed inside. And a diffusion chamber for performing a predetermined plasma treatment on the formed substrate.

Several types of antennas have been conventionally proposed for exciting helicon wave plasma of m = 0 mode and m = 1 mode. For example, m
In addition to the simplest single-loop antenna, the = 0 mode helicon wave plasma is generated in the plasma generation chamber by two loops that are separated by a distance equal to about half the wavelength of the propagating helicon wave and flow currents in opposite directions. It can be excited by using an orbiting double loop antenna. Further, the m = 1 mode helicon wave plasma can be excited by using a half-turn antenna that partially circulates in the plasma generation chamber. However, according to the present invention, it is necessary that two antennas are installed in the vicinity of a single plasma generation chamber so that they do not interfere spatially with each other. Therefore, for example, as a first antenna for exciting the m = 0 mode helicon wave plasma, a single loop antenna is installed in the top plate portion of the plasma generation chamber to excite the m = 1 mode helicon wave plasma. A half-turn antenna may be installed as the second antenna on the side wall of the plasma generation chamber.

The high frequency power supply means may include phase adjusting means for shifting the phases of the high frequencies supplied to the first antenna and the second antenna from each other. This is particularly effective in preventing resonance when the frequencies of the high frequencies supplied to both antennas are the same.
A relay circuit can be typically used as the phase adjusting means.

The high frequency power supply means also includes the first
Output adjusting means for independently controlling the high frequency power supplied to the antenna and the second antenna may be included.
A drive amplifier can be typically used as the output adjusting means.

The high frequency power supply means also includes the first
It may include a pulse power supply for intermittently supplying power to the antenna and the second antenna. The width of the pulse generated by this power supply is selected on the order of 10 μs (microsecond). This is because the relaxation time of the electron temperature is n
While it is on the order of s (nanoseconds), the fact that the life of plasma is long on the order of several tens of μs is used to periodically increase and decrease only the electron temperature while maintaining the plasma density substantially constant. is there. Since the electron temperature is a parameter that determines the dissociation reaction of the etching gas and the sheath voltage on the substrate surface, the pulse discharge as described above enables a high degree of dissociation control and ion / energy control.

Further, the high frequency power supply means may include high frequency switching means for switching the power supply to the first antenna and the second antenna at high speed.
When this switching is performed, m = 0 mode plasma and m = 1 mode plasma can be generated alternately, and the generation ratio of both plasmas depends on the switching timing.

As the magnetic field generating means, a solenoid
It is possible to use a coil and a magnetic field switching means for controlling supply / interruption of electric current to the solenoid coil.

Here, several methods can be considered for supplying the electric current to the solenoid coil, and the effect obtained by this method is also different. A magnetic field is not generated during the interruption of the current to the solenoid coil, but if a high frequency is supplied to at least one of the first antenna and the second antenna during this period, the inductively coupled plasma will be generated instead of the helicon wave plasma. Can be excited. That is, if there is a magnetic field generation / annihilation cycle where high-frequency power is continuously applied to the antenna, etching using inductively coupled plasma and helicon wave plasma alternately becomes possible. Since the inductively coupled plasma generally produces more radicals than the helicon wave plasma, the ion / radical production ratio is set to a desired value based on the length of the current supply time to the solenoid coil and the duty ratio of the current application. Can be controlled.

Alternatively, in particular, in a helicon wave plasma device in which the plasma generation chamber is circulated by two systems of solenoid coils, an inner circumference side and an outer circumference side, for example, the inner circumference side solenoid coil propagates the helicon wave and the outer circumference side. The role of each coil may be different, such that the solenoid coil of is used for transporting helicon wave plasma. In such a case, for example, a current is constantly applied to the inner solenoid coil, and the supply / cutoff of the current to the outer solenoid coil is controlled to control the helicon from the plasma generation chamber to the diffusion chamber. The wave plasma transport can also be controlled. This makes it possible to freely change the density of plasma that can be used near the substrate.

On the other hand, the dry etching method of the present invention is
Using a helicon wave plasma device capable of exciting m = 0 mode helicon wave plasma and m = 1 mode helicon wave plasma in a single plasma generation chamber, and accommodating in a diffusion chamber connected to the plasma generation chamber Dry etching is performed on the formed substrate.

Here, as one method, the dry etching can be performed simultaneously or intermittently by exciting the m = 0 mode helicon wave plasma and the m = 1 mode helicon wave plasma.

At this time, as described above, the output adjusting means for independently controlling the high frequency power supplied to the first antenna and the second antenna is provided, and the excitation of plasma in these two modes can be independently controlled. By using such a helicon wave plasma device, the generation ratio of both plasmas can be adjusted to achieve a desired ion current density distribution in the plasma generation chamber.

Further, the etching is divided into a just etching step of etching the material film to be etched substantially by the film thickness and an overetching step of etching the remainder of the material film to be etched. And the m = 0 mode helicon wave plasma and m = 1
It is also possible to change the generation ratio of the mode helicon wave plasma. In addition, these two modes of plasma are
When the frequencies of the high frequencies for excitation are the same, the phases may be shifted from each other.

The above is the dry etching method based on the simultaneous excitation of helicon wave plasma of m = 0 mode and m = 1 mode, but the excitation of both plasmas may be alternately switched at high speed. The generation time of each helicon wave plasma at this time can be adjusted so that a desired ion current density distribution in the plasma generation chamber is achieved.

Further, the dry etching can be performed while generating a magnetic field intermittently. in this case,
As described above, the inductively coupled plasma and the helicon wave plasma may be alternately excited to control the ion / radical production ratio, or the transport of the helicon wave plasma toward the substrate may be controlled to control the plasma density. May be.

[0030]

The m = 0 mode and the m = 1 mode helicon wave plasma have different saturated ion current density distributions, as shown in FIG. Since the helicon wave plasma device of the present invention is designed so that both plasmas can be excited in a single plasma generation chamber by including two antennas, the ion current density distribution in the chamber is It will be one that combines the character of the mode.
That is, the drop in the ion current density near the center of the chamber in the m = 0 mode can be compensated by the peak in the m = 1 mode, and as a result, the ion current density can be made uniform over a wide range in the chamber diameter direction. . Here, independently controlling the high frequency power supplied to the antennas of these two systems using the output adjusting means is equivalent to independently changing the peak heights of the two distribution curves in FIG. It is possible to control the ion current density distribution more precisely.

Furthermore, if a high-frequency power pulse is applied, the electron temperature can be controlled, and if the plasma in both m = 0 and m = 1 modes is alternately excited, the ion / radical production ratio can be controlled. It is possible to finely control the plasma according to the content of the desired plasma treatment.

When dry etching is carried out using such a helicon wave plasma, the etching rate and the etching speed can be reduced as compared with the case of using the conventional helicon wave plasma device which can excite only one mode of the helicon wave plasma at a time. The in-plane uniformity of the underlying film thickness can be significantly improved.

[0033]

EXAMPLES Specific examples of the present invention will be described below.

Embodiment 1 In this embodiment, a single loop antenna is arranged as the first antenna for m = 0 mode excitation in the top plate of the plasma generation chamber, and the second antenna for m = 1 mode excitation is used. A configuration example of a helicon wave plasma etching device in which a half-turn antenna as an antenna is wound around a side wall of a chamber and a normal power source and a pulse power source for supplying high frequency power to these two systems of antennas can be selected by a switch will be described. To do.

FIG. 3 shows a conceptual configuration of this etching apparatus. The plasma generation unit of this apparatus includes a plasma generation chamber 1 made of a dielectric material for generating a helicon wave plasma P _H, and the plasma generation chamber 1.
Single-loop antenna 6 for m = 0 mode excitation provided in parallel with the top plate 2 of m, and half-turn antenna 7 for m = 1 mode excitation partially circling the side wall surface of the same plasma generation chamber 1. The solenoid coil 8 that circulates in the plasma generation chamber 1 further outside the half-turn antenna 7 and generates a magnetic field along the axial direction is a main constituent element.

The constituent material of the plasma generating chamber 1 is, for example, quartz, and its diameter is, for example, 35 cm.

Mounting the above-mentioned two high frequency antennas,
The greatest feature of this device is that both antennas are connected to a common power supply system. This power supply system includes a normal high frequency power supply 13 and a high frequency pulse power supply 14
Includes two types of power supplies, one of which is switch 12
It is designed to be selected in. That is, if the terminal S1 of the switch 12 is selected, the normal high frequency power source 13
If the terminal S2 is selected, the high frequency pulse power supply 14 is connected to both antennas. A relay circuit (R / C) 63 as a phase adjusting means and a drive amplifier 6 as an output adjusting means are provided between the switch 12 and the single loop antenna 6.
2. A matching network (M / N) 61 for impedance adjustment is connected in this order. Further, between the switch 12 and the half-turn antenna 7,
Drive amplifier 72 and matching network (M / N)
71 are connected in this order. The relay circuit 63 includes a single loop antenna 6 and a half turn antenna.
Since the purpose is to shift the phases of the high frequencies supplied to the antennas from each other, they may be connected to the half-turn antenna 7 side contrary to the illustrated example. The phase shift caused by the relay circuit 63 is set to π / 2, for example.

The solenoid coil 8 has a double structure. The inner solenoid coil 8a mainly contributes to the propagation of the helicon wave and the outer solenoid coil mainly contributes to the transportation of the helicon wave plasma P _H. 8b
Consists of This solenoid coil is a DC power supply (D
/ C) 81.

A diffusion chamber 3 is connected to the plasma generation chamber 1 so as to draw the helicon wave plasma P _H into the diffusion chamber 3 along the divergent magnetic field formed by the solenoid coil 8. The side wall surface and the bottom surface of the diffusion chamber 3 are made of a conductive material such as stainless steel. The interior thereof is evacuated to a high vacuum in the direction of arrow A through an exhaust hole 4 by an exhaust system (not shown), and is supplied with a gas required for dry etching in the direction of arrow B from a gas supply pipe 5 opened at the ceiling. Further, the side wall surface thereof is connected to, for example, a load lock chamber (not shown) via a gate valve 17.

Further, outside the diffusion chamber 3,
A multipole magnet 11 is provided as an auxiliary magnetic field generating means in order to converge the divergent magnetic field in the vicinity of the wafer stage 9 and to suppress the disappearance of electrons and active species in plasma by the chamber wall. The multi-pole magnet 11 generates a multi-cusp magnetic field in the diffusion chamber 3 to confine plasma. The arrangement position of the multi-pole magnet 11 is not limited to the example shown in the figure, and may be another place such as around the pillar of the wafer stage 9. Further alternatively, this may be replaced by a solenoid coil, and the plasma may be confined by forming a mirror magnetic field.

Further, inside the diffusion chamber 3, a conductive wafer stage 9 electrically insulated from the wall surface is accommodated, on which a wafer W, for example, is held as a substrate to be processed and a predetermined plasma is held. Processing (dry etching here) is performed. The wafer stage 9 is supplied with a coolant from a chiller (not shown) for maintaining the wafer W in process at a desired low temperature, and a cooling pipe 10 for circulating the coolant in the directions of arrows C ₁ and C _2. Has been inserted. In the case of controlling the wafer temperature as described above, it is effective to improve the heat conduction between the wafer W and the wafer stage 9. For this purpose, the wafer Stage 9
Should be used.

Further, on the wafer stage 9, a bias applying high frequency power source 16 for applying a substrate bias to the wafer W in order to control the energy of ions entering from the plasma is provided with a second matching network (M).
/ N) 15. Here, the frequency of the bias applying high frequency power source 16 is 13.56 MHz.

Example 2 In this example, the helicon wave plasma etching apparatus described in Example 1 was used, and m = 0 mode plasma and m in the just etching process and the overetching process.
The Al-based wiring film was subjected to two-step etching while changing the generation ratio of the = 1 mode plasma. The process of this embodiment will be described with reference to FIGS.

FIG. 6 shows a cross section of the main part of a wafer used as an etching sample in this example. This wafer is
An Al-based wiring film 24 is formed on the SiOx interlayer insulating film 20, and a resist mask 25 is further formed thereon in a predetermined pattern. Where A
The l-based wiring film 24 includes, for example, a Ti-based barrier metal 21 in which a Ti film and a TiN film are stacked in this order, and Al-1% S.
The i film 22 and the TiON antireflection film 23 are sequentially laminated.

The resist mask 25 is made of, for example, a chemically amplified resist material and is made of KrF excimer.
The pattern width is, for example, 0.35 μm through laser lithography.

This wafer is set on the wafer stage 9 of the helicon wave plasma apparatus described in the first embodiment, the terminal S1 of the switch 12 is selected, and the Al wiring film 24 is formed.
As an example, just etching was performed under the following conditions.

BCl ₃ flow rate 50 SCCM Cl ₂ flow rate 50 SCCM Gas pressure 0.13 Pa Single loop antenna supply power 2000 W (13.56 MHz) Half turn antenna supply power 2500 W High frequency bias power 100 W (13.56) MHz) Wafer stage temperature 20 ° C. By this just etching, as shown in FIG. 7, it was possible to almost form an Al-based wiring pattern having an anisotropic shape. In the drawings, the material film anisotropically processed by etching is represented by adding the subscript a to the original code. Since the etching of the Al-based wiring film proceeds mainly in the radical mode, the etching rate generally becomes higher in the peripheral portion of the wafer where the exhaust rate of the reaction products is higher due to the exhaust flow in the chamber. However, in the present invention, since the etching is performed in a state where the plasma density near the center of the chamber is increased by using the plasma of the m = 0 mode and the plasma of the m = 1 mode together, a decrease in the etching rate in the central portion of the wafer is caused. It was possible to suppress, and it was possible to achieve an excellent etching in-plane uniformity of ± 1% even on a wafer having a diameter of 8 inches.

However, as shown in FIG. 7, it is necessary to remove the residual portion 24r of the Al-based wiring film that slightly remains on the wafer. Therefore, overetching for this purpose is performed under the following conditions as an example. It was

BCl ₃ flow rate 50 SCCM Cl ₂ flow rate 50 SCCM Gas pressure 0.13 Pa Single loop antenna supply power 2500 W (13.56 MHz) Half turn antenna supply power 2500 W High frequency bias power 60 W (13.56) MHz) Wafer stage temperature 20 ° C. By this over-etching, as shown in FIG. 8, the Al-based wiring pattern 24a was completed and the underlying SiOx interlayer insulating film 20 was slightly etched.
Since the etching of SiOx proceeds mainly in the ion mode, radicals like those in the just etching described above are used.
If the mode-dominant condition continues, the reduction in the thickness of the SiOx interlayer insulating film 20 becomes uneven. However, in the present invention, the single loop
Since the power supplied to the antenna is increased to increase the generation ratio of m = 0 mode plasma, a high ion current density can be uniformly obtained, and the uniformity of the film reduction of the underlying SiOx interlayer insulating film 20 is ± 5. I was able to reduce it to%.

[0050] In the implementation example 3 This example, using a helicon wave plasma etching apparatus described above in Example 1, and m = 0 mode plasma and m = 1 mode plasma using a high frequency pulse power supply 14 simultaneously The contact hole was etched in one step while intermittently generating it.

The sample wafer used in this example is shown in FIG. This wafer has, for example, O on a Si substrate 30 in which an impurity diffusion region 31 as a lower layer wiring is formed in advance.
A SiOx interlayer insulating film 32 having a thickness of about 1.0 μm formed by _2- TEOS plasma CVD is laminated, and a resist mask 33 is further formed thereon. The resist mask 33 is formed by using a halftone type phase shift mask to form an opening 34 having an opening diameter of about 0.25 μm.

This wafer is set in the helicon wave plasma device described in the first embodiment, and the terminal S2 of the switch 12 is selected to connect the high frequency pulse power supply 14 to the single loop antenna 6 and the half turn antenna 7. The SiOx interlayer insulating film 32 was etched while supplying high frequency waves having different phases to both antennas at the same time. An example of etching conditions is shown below.

C-C ₄ F ₈ flow rate 50 SCCM CO flow rate 50 SCCM gas pressure 1.3 Pa single loop antenna supply power 2500 W (13.56 MHz) half turn antenna supply power 2500 W switching period 10 μs high frequency bias Electric power 300 W (13.56 MHz) Wafer stage temperature 0 ° C. Here, the above-mentioned CO extracts O atoms in SiOx by its reducing action to speed up etching, and captures excessive F ^* during overetching. And S of the groundwork
It is a gas added to secure the selectivity for the i-substrate 30. ． However, in the case of high-density plasma such as helicon wave plasma, the electron temperature rises excessively in normal continuous discharge, and CO is dissociated into C and O, and CO cannot fulfill its desired role. However, in this embodiment, the electron temperature is lowered by continuing the plasma discharge by the intermittent application of the high frequency, so that the dissociation of CO can be controlled to an appropriate level and both the high speed etching and the high selectivity can be achieved. . Moreover, since the helicon wave plasmas of both m = 0 mode and m = 1 mode are simultaneously excited, the uniformity of plasma is extremely high. By the above etching, as shown in FIG. 10, the contact hole 35 having a good anisotropic shape could be formed. At this time, the etching rate is about 1 μm / min, and the selection ratio to Si is about 10
0, in-plane uniformity ± 2% could be achieved.

Embodiment 4 In this embodiment, a helicon wave plasma device equipped with a high frequency switching means for switching the power supply to the single loop antenna 6 and the half turn antenna 7 at high speed will be described.

FIG. 4 shows a conceptual configuration of this etching apparatus. The apparatus described in Example 1 (see FIG. 3).
The description of the common parts with and is omitted.

This device differs from the device of the first embodiment in that the relay circuit 63 for phase adjustment is not connected to the power supply system for the single loop antenna 6, and instead,
The high-speed switching circuit 1 is provided after the normal high frequency power supply 13.
8 are connected. This high-speed switching circuit 18 can perform switching in the order of several to several tens of microseconds, and switches its mode between m = 0 and m = 1 while continuing plasma excitation, whereby the chamber radial direction. The ion current density distribution can be made uniform.

Example 5 In this example, the Al-based wiring film was etched in one step using the helicon wave plasma device described in Example 4. The sample wafer used is the same as that used in Example 2. An example of etching conditions is shown below.

BCl ₃ flow rate 50 SCCM Cl ₂ flow rate 50 SCCM Gas pressure 0.13 Pa Single loop antenna power supply 2500 W (13.56 MHz) Half turn antenna power supply 2500 W High frequency bias power 60 W (13.56) MHz) High-frequency switching period 15 μsec Wafer stage temperature 20 ° C. In the present embodiment, etching and the underlying SiOx layer 2 are formed by using helicon wave plasma of m = 0 mode and m = 1 mode which are alternately generated while switching at high speed.
It was possible to achieve extremely excellent in-plane uniformity for both of the film reductions of 0.

Embodiment 6 In this embodiment, a helicon wave plasma device in which a DC power source is connected to an inner circumference side solenoid coil 8a which mainly contributes to the propagation of a helicon wave among the solenoid coils 8 through a magnetic field switching means. explain.

The conceptual configuration of this device is shown in FIG. In the high frequency power supply system of this device, the switch 12 and the pulse power supply 14 are omitted from FIG. 3 described above, and the phases of the single loop antenna 6 and the half turn antenna 7 are deviated from each other. High frequency is continuously supplied.

On the other hand, in the magnetic field generating means, the DC power source (D / C) 81 is connected to the inner solenoid coil 8a mainly contributing to the propagation of the helicon wave via the switch 82.

The greatest feature of this apparatus is that the O of the switch 82 is
The point is that the inductively coupled plasma P _I and the helicon wave plasma P _H can be excited alternately by N / OFF. That is,
As shown in FIG. 5, the switch 82 is turned off, and a DC power source (D / C) 81 is connected to the inner solenoid coil 8a.
When no current is supplied from the helicon wave plasma P _H, no magnetic field is generated in the plasma generation chamber 1.
Is not generated, and inductively coupled plasma P _I is generated instead. On the contrary, when the switch 82 is turned on and a current is supplied from the DC power supply (D / C) 81 to the inner solenoid coil 8a, m = 0 in the plasma generation chamber 1.
Mode and m = 1 mode helicon wave plasma P _H is generated. Since the inductively coupled plasma P _I generally has a high radical density and the helicon wave plasma P _H generally has a high ion density, a desired ion / radical production ratio can be obtained by optimizing the ON / OFF timing of the switch 82 in such a device. be able to.

Example 7 In this example, the Al-based wiring film was etched in one step using the helicon wave plasma device described in Example 6. The sample wafer used here is the same as that used in Example 2. An example of etching conditions is shown below.

BCl ₃ flow rate 50 SCCM Cl ₂ flow rate 50 SCCM Gas pressure 0.13 Pa Single loop antenna power supply 2500 W (13.56 MHz) Half turn antenna power supply 2500 W High frequency bias power 60 W (13.56) MHz) Magnetic field switching period 20 μsec Wafer stage temperature 20 ° C. The etching of the Al-based wiring film 24 proceeds essentially in the radical mode, but the conventional helicon wave plasma etching apparatus is insufficient in radical components, so that it is sufficient. No etching rate was obtained. On the other hand, in the present embodiment, since the helicon wave plasma and the inductively coupled plasma P _I were alternately excited, the lack of radicals could be compensated. In addition, the ion assist mechanism was able to function effectively while taking advantage of the advantage of low-voltage discharge that secures the straightness of the active species and suppresses the micro-cracking effect.

As a result, the Al-based wiring pattern 24a having a good anisotropic shape as shown in FIG. 8 could be formed at a high etching rate of 1.2 μm / min.

Although the present invention has been described above based on seven embodiments, the present invention is not limited to these embodiments, and the details of the structure of the sample wafer and the structure of the helicon wave plasma device are not limited thereto. The dry etching conditions can be appropriately changed and optimized.

[0067]

As is apparent from the above description, by applying the present invention, it becomes possible to finely adjust the plasma density in the chamber radial direction, which cannot be achieved by the conventional helicon wave plasma device, and the contents of etching can be adjusted. It is possible to finely optimize the etching conditions according to the above. As a result, high speed in dry etching, anisotropy,
Conflicting requirements such as in-plane uniformity, underlayer selectivity, and suppression of microloading effect can all be satisfied at a practical level. Therefore, the present invention greatly contributes to high integration, high performance, and high reliability of semiconductor devices.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing electric field patterns of helicon wave plasma in m = 0 mode and m = 1 mode.

FIG. 2 is a graph showing saturated ion current density distributions of helicon wave plasma in m = 0 mode and m = 1 mode.

FIG. 3 is a schematic cross-sectional view showing a configuration example of a helicon wave plasma device of the present invention capable of simultaneous continuous / intermittent excitation of m = 0 mode and m = 1 mode helicon wave plasma.

FIG. 4 is a schematic cross-sectional view showing a configuration example of a helicon wave plasma device of the present invention capable of alternately exciting helicon wave plasma of m = 0 mode and m = 1 mode.

FIG. 5 is a schematic cross-sectional view showing a configuration example of a helicon wave plasma device of the present invention capable of alternately exciting helicon wave plasma of m = 0 mode and m = 1 mode and inductively coupled plasma.

FIG. 6 is a schematic cross-sectional view showing a state where a resist mask is formed on an Al-based wiring film in dry etching of the Al-based wiring film to which the present invention is applied.

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

[FIG. 8] As a result of performing over-etching, the underlying Si
FIG. 6 is a schematic cross-sectional view showing a state in which the Ox interlayer insulating film is uniformly thinned.

FIG. 9 is a view showing a resist layer formed on a SiOx interlayer insulating film in dry etching of a contact hole to which the present invention is applied.
It is a typical sectional view showing the state where a mask was formed.

10 is a schematic cross-sectional view showing a state in which a contact hole is opened by dry etching the SiOx interlayer insulating film of FIG.

[Explanation of symbols]

 1 Plasma Generation Chamber 3 Diffusion Chamber 6 Single Loop Antenna 7 Half Turn Antenna 8 Solenoid Coil 8a Inner Circumferential Solenoid Coil 8b Outer Circumferential Solenoid Coil 9 Wafer Stage 12 Switch 13 High Frequency Power Supply 14 Pulse Power Supply 15, 61, 71 Matching Network 16 High Frequency Power Supply for Biasing 18 High Speed Switching Circuit 62, 72 Drive Amplifier 63 Relay Circuit 81 DC Power Supply 82 Switch 20, 32 SiOx Interlayer Insulation Film 24 Al-based Wiring Film 24a Al-based Wiring Pattern 25, 33 Resist Mask 35 contact holes

Claims (12)

[Claims] 1. A plasma generation chamber made of a dielectric material, a first antenna for exciting m = 0 mode helicon wave plasma inside the plasma generation chamber, and m = inside the plasma generation chamber. A second antenna for exciting a one-mode helicon wave plasma, a high-frequency power supply means for supplying high-frequency power to the first antenna and the second antenna, and an inside of the plasma generation chamber that circulates. A helicon wave plasma device having a magnetic field generating means for generating a magnetic field and a diffusion chamber connected to the plasma generating chamber and performing a predetermined plasma treatment on a substrate housed inside. 2. The helicon wave plasma device according to claim 1, wherein the high frequency power supply means includes a phase adjustment means for shifting the phases of the high frequencies supplied to the first antenna and the second antenna from each other. 3. The helicon wave plasma apparatus according to claim 1, wherein the high frequency power supply means includes an output adjusting means for independently controlling high frequency power supplied to the first antenna and the second antenna. 4. The helicon wave plasma device according to claim 1, wherein the high-frequency power supply means includes a pulse power supply that intermittently supplies power to the first antenna and the second antenna. 5. The helicon wave plasma device according to claim 1, wherein the high-frequency power supply means includes high-frequency switching means that switches power supply to the first antenna and the second antenna at high speed. 6. The magnetic field generating means includes a solenoid coil, and a current supply / supply to the solenoid coil.
The helicon wave plasma device according to claim 1, further comprising magnetic field switching means for controlling interruption. 7. m = 0 in a single plasma generation chamber
Using a helicon wave plasma device capable of exciting helicon wave plasma of mode and helicon wave plasma of m = 1 mode, and performing dry etching on a substrate accommodated in a diffusion chamber connected to the plasma generation chamber Etching method. 8. The dry etching method according to claim 7, wherein the dry etching is performed while simultaneously and continuously exciting the m = 0 mode helicon wave plasma and the m = 1 mode helicon wave plasma. 9. The dry etching method according to claim 7, wherein the dry etching is performed while intermittently exciting the m = 0 mode helicon wave plasma and the m = 1 mode helicon wave plasma at the same time. 10. The dry etching includes a just etching step of etching a material film to be etched on the substrate substantially by a film thickness thereof and an overetching step of etching a remainder of the material film to be etched. 8. The dry etching method according to claim 7, wherein the dry etching method is performed separately, and the generation ratio of the m = 0 mode helicon wave plasma and the m = 1 mode helicon wave plasma is changed between both steps. 11. The dry etching method according to claim 7, wherein in the dry etching, excitation of m = 0 mode helicon wave plasma and m = 1 mode helicon wave plasma is switched at high speed. 12. The dry etching method according to claim 7, wherein the dry etching is performed while generating a magnetic field intermittently.