JPH04268727A - Method and adevice for dry etching - Google Patents

Abstract

PURPOSE:To provide the title dry etching method in excellent evenness, easy to be large-scaled doping little damage to a work for producting high density plasma in high degree of vacuum making use of the oscillation or rotary motion of electrons in the pertient high-frequency field. CONSTITUTION:The title dry etching device is provided with a mechanism wherein the space between the first electrode pair 5 and 6 is impressed with the first high-frequency power in 300 MHz and then the space between the second electrode pair 7 and 8 is impressed with the first high-frequency power in the 90 deg. different phase while the space between the remaining one pair of electrodes 2 and 4 is impressed with the second high-freqnency power of 50 MHz. Since Lissajour's waveforms are observed when the signals in the 90 deg. different phase of the same freqnency are inputted in X, Y of an oscilloscope, similar to such a case, electrodes start rotary motion due to the AC power imposed on the electrodes 5, 6, 7, 8. Accordingly, the high ionization effect can be brought about for increasing the etching rate despite the high degree of vacuum.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to dry etching technology using plasma.

0002

2. Description of the Related Art Advances in high-density semiconductor integrated circuits are bringing about changes that can be compared to the industrial revolution. High density has been achieved by miniaturizing element dimensions, improving devices, increasing chip size, etc. The miniaturization of element dimensions has progressed to the level of the wavelength of light, and the use of excimer lasers and soft X-rays for lithography is being considered. Along with lithography, dry etching plays an important role in realizing fine patterns.

[0003] Dry etching is a processing method that removes unnecessary portions of a thin film or substrate by utilizing a chemical or physical reaction between a gas phase and a solid phase surface caused by plasma, radicals, ions, etc. Reactive ion etching (RIE) is the most widely used dry etching technique.
) is that when a sample is exposed to a high-frequency discharge plasma of an appropriate gas, unnecessary portions of the sample surface are removed by an etching reaction. The necessary areas are usually protected by a photoresist pattern used as a mask. For miniaturization, it is necessary to align the directionality of ions, and for this purpose, it is essential to reduce the scattering of ions in the plasma. In order to align the directionality of the ions, it is effective to increase the degree of vacuum of the plasma to increase the mean free path of the ions, but there is a problem that increasing the degree of vacuum makes it difficult to generate high-frequency discharge. As a countermeasure to this problem, a magnetic field is generally applied to the plasma chamber, and methods such as magnetron reactive ion etching and E
CR (Electron Cyclotron Resonance) etching techniques have been developed.

FIG. 14 is a schematic diagram showing a conventional reactive ion etching apparatus using magnetron discharge. A reactive gas is introduced into the metal chamber 81 through a gas controller 82 and controlled to an appropriate pressure by an exhaust system 83. An anode (anode) 84 is provided at the top of the chamber 81, and a cathode (cathode) is provided at the bottom.
A sample stage 85 is provided. On the sample stage 85,
An RF power source 87 is connected via an impedance matching circuit 86, and a high frequency discharge can be caused between the sample stage 85 and the anode 84. Inside the chamber 81,
A rotating magnetic field is applied by two pairs of opposing alternating current electromagnets 88 with a phase difference of 90 degrees installed on the side, facilitating discharge in a high vacuum. Due to the applied magnetic field, the electrons
Because of the cycloidal motion, the ionization efficiency is increased.

[0005]

[Problem to be solved by the invention] However, although the purpose of magnetron discharge and ECR discharge as described above is to increase plasma density, sufficient consideration must be given to generating a high plasma density uniformly over the entire sample surface. It has not been. For this reason, there was a problem in that damage was introduced into the sample to be processed. For example, in conventional magnetron reactive ion etching equipment, local plasma polarization is time-averaged using a rotating magnetic field to make it uniform, but because the instantaneous plasma density is not uniform, a local potential difference is generated, and the MOSLSI process If applied to the above, the gate oxide film may be destroyed. Similarly, in an ECR etching apparatus, since the magnetic field has a distribution in the radial direction of the chamber, local density of plasma density causes non-uniformity of etching species and local potential difference. This plasma non-uniformity deteriorates etching uniformity, making it difficult to produce LSIs with a high yield. This means that uniform etching is even more difficult in dry etching of ultra-fine patterned LSIs in which thinner gate oxide films are used or in the use of large diameter wafers.

100 to 200 MHz to the conventional parallel plate type magnetron etching device with 13.56 MHz excitation.
Attempts have also been made to superimpose high-frequency power to increase plasma density, reduce self-bias voltage, and reduce damage to samples caused by high-energy ions. Even with this method, it is still difficult to improve plasma uniformity, and it cannot be said to be sufficient to solve problems caused by plasma non-uniformity.

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a dry etching technique under high vacuum that has excellent microfabrication properties, good uniformity, and less damage to devices.

[0008]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the dry etching apparatus of the present invention includes an electrode pair and a sample stage arranged around a plasma generation part in a vacuum chamber into which a reactive gas for etching is introduced. has a high-frequency power supply that applies high-frequency power with a cycle shorter than the time required for electrons to travel the distance between the electrodes to the electrode pair, and a sample placed on a sample stage. It is configured to generate plasma by vibrating electrons in the generating section, and to irradiate reaction products generated in the plasma onto a sample placed on a sample stage.

Alternatively, the dry etching apparatus of the present invention includes a plurality of electrode pairs and a sample stage arranged around a plasma generation part in a vacuum chamber into which a reactive gas for etching is introduced;
Multiple high-frequency power supplies apply high-frequency power or harmonic high-frequency power with equal frequencies and different phases to multiple electrode pairs, and the application of high-frequency power rotates electrons in the plasma generation part to generate plasma, and generates plasma. The sample is placed on a sample stage and is irradiated with the reaction product generated in the sample stage. .

In carrying out the present invention, it is desirable to provide a phase lock mechanism that controls high frequency power of the same frequency with different phases or high frequency power of harmonics thereof to a constant phase difference. Furthermore, it is desirable to apply high frequency power of the same frequency and different phases, or high frequency power of harmonics thereof, which are generated from the same signal source.

[0011]

[Operation] With the above-described structure, the present invention applies high frequency power to one or more pairs of electrodes to cause the electrons in the chamber to move in a Lissajous figure such as vibration, rotation, or cycloid. This electron movement effectively increases the collision cross section between electrons and gas molecules, so compared to conventional parallel plate dry etching equipment, higher ionization efficiency can be obtained even in high vacuum, and discharge is easier. be. Compared to conventional magnetron discharge and ECR discharge using magnetic field support, the device of the present invention has better plasma uniformity because the high-frequency electric field in the chamber is more uniform than the magnetic field distribution of those devices, and the device is larger. is also easy. Furthermore, since there is almost no local deviation of the plasma, damage to the device such as destruction of the gate oxide film is also extremely small. Furthermore, since the vacuum is higher than in conventional parallel plate dry etching equipment, there is less ion scattering by gas molecules, resulting in highly anisotropic etching.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS A dry etching apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing the structure of an embodiment of the dry etching apparatus of the present invention. In FIG. 1, 1 is a chamber (vacuum chamber), 2 is a sample stage to which 50 MHz high frequency power is applied, and 3 is a semiconductor wafer, which is a sample to be etched, placed on the sample stage 2. 4 is a counter electrode of the sample stage 2, and 5, 6, 7, and 8 are electrode pairs to which 300 MHz high frequency power is applied. The phase of the power applied between electrodes 5 and 6 is approximately 90 degrees different from the phase of power applied between electrodes 7 and 8. The area surrounded by the electrodes 2, 4 to 8 is a plasma generating section, and the electrodes 2, 4 to 8 are arranged around this plasma generating section. Etching gas is introduced into the chamber 1 from an inlet (not shown) via a mass flow controller (not shown), and the pressure inside the chamber is set to 0.1 by a turbo pump (not shown).
It is controlled from Pa to about 10 Pa. electrodes 5, 6,
Amplifiers 9 and 10 that supply high frequency power to amplifiers 7 and 8 via matching circuits 12 and 13 are controlled by a phase lock mechanism 11 to have a constant phase difference (90 degrees). Further, in order to equalize the frequencies, a signal generated from one signal source is amplified, and the amplifiers 9 and 10 supply alternating current power of the same frequency and different phases. Further, high frequency power of 50 MHz is amplified by an amplifier 14 and supplied to the sample stage 2 via a matching circuit 15. As will be described in detail later, the electrons rotate in the same direction in the chamber, so a magnetic field is generated from the plasma. Reference numeral 16 denotes a Hall element, which is used to control the high frequency power applied to the electrodes 5 to 8 based on the fact that the strength of the magnetic field radiated from the plasma is proportional to the plasma density.

The operation of the dry etching apparatus constructed as described above will be explained below with reference to FIG.

FIG. 2a is a diagram schematically showing the trajectory of electrons e when high frequency power is applied to a pair of parallel plate electrodes 5 and 6. The electron e travels in the direction of its own kinetic energy while vibrating due to the high frequency electric field between the electrodes 5 and 6. Figure 3 shows the distance traveled by electrons during one period of high frequency as a function of frequency. In this case 20eV
electrons are assumed. For example, an electron traveling in the X direction with an energy of 20 eV moves about 6 cm in 20 nanoseconds, which corresponds to one period of high frequency power of 50 MHz. Assuming that the distance between the electrodes is 30 cm, the bicycle will be vibrated approximately 5 times while running that distance. If the energy of the electron is high, its speed is also high, so the frequency of vibration while traveling between the electrodes decreases.

[0016] Although it differs depending on the type of gas, electron energy of approximately 15 eV or more is generally required to ionize a gas. Furthermore, since ionization is caused by collisions between electrons and gas molecules, the longer the distance traveled by electrons, the higher the probability of collision and the higher the ionization efficiency. In the present invention, the travel distance of the electrons is increased by causing the electrons to vibrate or rotate, thereby increasing the ionization efficiency. Alternatively, it can be considered that the vibrational or rotational motion of the electrons effectively increases the collision cross section with the gas molecules. The distance between electrodes 5 and 6 is usually a number 1
0 cm 2 , a high frequency of approximately 50 MHz or higher is required to vibrate electrons with high frequency and improve ionization efficiency. However, even if the travel distance due to vibration or rotational motion of electrons is no longer increased at frequencies lower than 50MHz, the probability that electrons collide with the chamber wall and disappear due to the vibration or rotation of lower-energy electrons decreases, and the electron density decreases. This prevents a decrease in
Ionization efficiency is high.

[0017] Such high frequency power of 50 MHz or more has conventionally been used only for microwave discharge using a microwave power source using a magnetron in the GHz band, and has hardly been used for plasma generation. .

To the electrons in the state shown in FIG. 2a, a high-frequency power having the same frequency with a phase difference of 90 degrees perpendicular to the previous high-frequency electric field is applied.
The case where the voltage is applied to a pair of parallel plate electrodes 7 and 8 is shown in FIG. 2b. The electron e thus begins a rotational motion. This is the same frequency for the X signal input and Y signal input of the oscilloscope.
This is similar to the so-called Lissajous waveform that can be seen when signals with 0 degrees of phase difference are input. The Lissajous waveform has different waveforms depending on the phase difference of the high frequency power input to XY. FIG. 4 shows the relationship between the phase difference and the Lissajous waveform. The dry etching technique of the present invention aims to improve ionization efficiency by causing electrons to vibrate or rotate using an electric field in this manner.

In a conventional magnetron etching apparatus using a rotating magnetic field, the magnetic flux distribution 20 directly above the sample stand at a certain moment is
is non-uniform as shown in Figure 5a. For this reason, the electron e (black circle in Figure 5b) in the chamber rotates with an orbital radius that is inversely proportional to the magnetic field strength, so the radius of the electron in the area where the magnetic field strength is weak increases, causing the electron e to collide with the chamber wall. disappears. Therefore, the electron density decreases in areas where the magnetic field strength is weak, and the plasma density also decreases. This resulted in non-uniform plasma density, resulting in non-uniform etching and damage to the workpiece.

On the other hand, when the dry etching apparatus of the present invention is used, the gap between the parallel plate electrodes 5 and 6 and between the electrodes 7 and 8 is
Since the electric field is uniform throughout the area, the radius of rotation of the electrons is also the same at each location as shown in FIG. The product is uniformly irradiated over the entire surface of the sample 3. Therefore, etching is uniform over the entire sample area facing the plasma generating section 21, and damage caused by charge-up is extremely small. Moreover, the plasma density is high and the etching rate is high.

FIG. 7(a) schematically shows an example in which boron phosphorus glass is etched with a conventional magnetron etching apparatus using a rotating magnetic field. In the figure, 30 is a Si substrate;
31 is boron phosphorus glass, and 32 is a photoresist pattern. When the instantaneous magnetic field strength distribution directly above the Si substrate 30 has a minimum value at the center of the sample stage, as shown in FIG. The flux I is proportional to the plasma density distribution according to the magnetic field strength distribution, and becomes sparse in the center as shown in FIG. 7(a). Oxide film (bororin glass 3
The etching rate in 1) also follows approximately the ion flux I as shown in FIG. 7(c), and is non-uniform. In addition, non-uniform plasma density causes damage due to uneven distribution of charges.

On the other hand, according to the dry etching technique of the present invention, since uniform plasma is generated as described above, the etching plasma incident on the surface of the Si substrate 30 as shown in FIG. The ion flux II, which is a reaction product, also becomes uniform, and the etching rate also becomes highly uniform as shown in FIG. 4(b). Furthermore, since the plasma is uniform, uneven distribution of charges is small, and damage caused by charges is extremely small. In this case, a gas based on fluorocarbon gas such as CHF3+O2 or CF4+CH2F2 is used as the gas introduced into the chamber, and the pressure is 0.1 to 10.
I went with Pa. At this time, the etching rate was 100 to 350 nm/min. The method of the present invention is particularly suitable for etching submicron patterns and etching large diameter semiconductor wafers such as 6 inches and 8 inches. This is because the pressure inside the chamber is low, so there is little ion scattering, and the dimensional shift (so-called CD loss) due to etching from the photoresist pattern and the dependence of the etching rate on the pattern dimension are small. Another reason is that the structure has high plasma uniformity and allows the chamber to be easily enlarged.

In another experiment using the dry etching apparatus of the present invention, a gas containing SF6 mixed with a trace amount of oxygen was used, and the material to be etched was phosphorus-doped polycrystalline Si. Experimental results have shown that the present invention is highly effective when an electronegative gas such as SF6, oxygen, chlorine, or iodine is used as the etching gas. In the high-frequency plasma of electronegative gas, the electron density is low and the resistance is high, so the potential gradient in the plasma is larger than that in electropositive gas, so the effect of the present invention is particularly large. In this case as well, since the electric field inside the parallel plate electrodes is uniform, a plasma with good uniformity can be obtained, and the uniformity of etching is also good. Furthermore, since there is almost no local deviation of the plasma, damage to devices such as destruction of the gate oxide film of MOSLSI is extremely reduced. The etching rate is 200 to 400 nm/min.

In FIG. 1, the magnetic field strength generated by the rotational movement of electrons in the plasma is detected by the Hall element 16, and using the fact that the magnetic field strength is proportional to the plasma density, high-frequency power is applied so that the value becomes a set value. The plasma state is also kept constant by increasing and decreasing the amount. This allows direct feedback from the plasma state, making it possible to achieve good reproduction of the plasma state.

Although this example shows the case of oxide film and polycrystalline silicon etching, the present invention can also be used to obtain high effects in etching of Si compounds, metals such as Al, resist etching in multilayer resists, etc. It will be done. In that case, the effect will be even better if an electronegative gas such as chlorine, SF6, O2, etc. is used.

FIG. 9 shows a comparison between the conventional dry etching method and the dry etching method of the present invention. It can be seen that the dry etching method of the present invention is superior to the conventional method.

As described above, according to this embodiment, the high frequency power of the first frequency is applied to the first opposing electrodes 5 and 6, and the high frequency power of the first frequency is applied to the second opposing electrodes 7 and 8. applies high frequency power of a first frequency with a phase difference of approximately 90 degrees,
By making circular motion (including elliptical motion) of electrons in the vacuum (plasma generation section), high density and uniform plasma is generated despite the high vacuum.
By controlling the application of 50 MHz high-frequency power to the opposing electrodes constituting the substrate, it was also possible to control the selectivity with respect to the underlying layer during etching. Furthermore, since there is almost no local deviation of the plasma, damage to the workpiece can be extremely reduced.

[0028] In this example, the case where the phase difference of the high frequency power is constant at 90 degrees is shown, but this case has the highest efficiency of power input to the plasma, and even if the phase difference is different from 90 degrees, The effects of the present invention can be obtained. Alternatively, the phase may be changed as a function of time.

A second embodiment of the present invention will be described below with reference to the drawings. FIG. 10 is a schematic diagram showing the structure of a dry etching apparatus according to a second embodiment of the present invention. In FIG. 10, 41 is a chamber, 42 is 13.56
A sample stage to which MHz high-frequency power is applied, 43 is a ground electrode serving as a counter electrode, 44 and 45 are each 150 MH
Cathode electrodes 46 and 47 to which high frequency power of 300 MHz is applied are earth electrodes serving as opposing electrodes. Although the phases of the powers applied to the electrodes 44 and 45 are the same, they may be different. 48, 49, and 50 are matching circuits. The pressure inside the chamber 41 is controlled to about 0.1 Pa to 10 Pa by a turbo pump (not shown). In order to keep the frequency ratio constant to the electrodes 44 and 45, the amplifiers 51 and 52 that supply high frequency power multiply and amplify the signal generated from one signal source, and each
It supplies high frequency power of 0MHz and 300MHz. Amplifiers 51 and 52 that supply high frequency power are controlled by a phase lock mechanism 54 to have a constant phase difference (0 degrees in this case). The chamber 41 confines plasma by a caps magnetic field formed by a coil 55.

The difference from FIG. 1 is that different high frequency powers of 150 MHz and 300 MHz are applied to the electrodes 44 and 45, respectively, and that a caps magnetic field is formed by a coil 55 to confine the plasma.

Similar to FIG. 2, FIG. 11 schematically shows an example of the trajectory of electrons e in the chamber of the dry etching apparatus projected onto a horizontal plane. Again, the electrode 44
The AC power applied to , 45 causes the electrons to form a “figure 8” shape.
Due to its rotational motion, high ionization efficiency and high plasma density are obtained despite being in a high vacuum. When applied to oxide film etching, CHF3+O2, CF4+
Using a fluorocarbon-based gas such as CH2F2,
The pressure was 0.1-10 Pa. At this time, an etching rate of 150 to 500 nm/min was obtained.

As described above, according to this embodiment, high frequency power of frequency F is applied to the first pair of electrodes 44 and 46 among the three pairs of electrodes, and the high frequency power of frequency F is applied to the second pair of electrodes 45 and 47. A high frequency power with a frequency of 2F is applied to the remaining third pair of electrodes 42 and 4, which constitute a sample stage on which the sample to be etched is placed.
By providing 3 with a mechanism for applying high-frequency power of a different frequency, plasma with good uniformity can be obtained, and the uniformity of etching can also be made good. Furthermore, since there is almost no local deviation of the plasma, damage to the device such as destruction of the gate oxide film can be extremely reduced. Note that in this embodiment, the ground electrodes (46, 48, 43) of the first, second, and third high-frequency power supplies are at the same potential; 48)
The potentials of the ground electrode (43) and the third high-frequency power source may be different.

FIG. 12 is a schematic diagram showing the structure of a dry etching apparatus according to a third embodiment of the present invention. In FIG. 12, 42 is a sample stage to which 300 MHz high frequency power is applied, 44 and 45 are electrodes to which 300 MHz high frequency power is applied, and 43, 46, and 47 are opposing electrodes. The phase of the power applied to the electrodes 44 and 45 is
They are advancing by about 120 degrees relative to 2, and are also lagging behind. The pressure inside the chamber is controlled to about 0.1 Pa to 10 Pa by a turbo pump (not shown). In order to equalize the frequencies of the electrodes 42, 44, and 45,
Amplifiers 51, 52, and 53 that supply high-frequency power amplify the signal generated from one signal source, and
It supplies high frequency power of Hz. Amplifiers 51, 52, and 53 that supply high-frequency power have a constant phase difference (in this case, 120 degrees each) by a phase lock mechanism 60.
It is controlled to become.

The difference from FIG. 1 is that high-frequency power of 300 MHz and a phase difference of 120 degrees is applied to the electrodes 42, 44, and 45, respectively.

In this case, the electrons in the chamber 41 are rotated on a spherical surface by high frequency power, and high ionization efficiency and high plasma density can be obtained despite being in a high vacuum.

When applied to aluminum etching,
Using a chlorine-based gas such as BCl3+Cl2, SiCl4+Cl2+CHCl3, the pressure is 0.1-20
It was set as Pa. At this time, the etching rate is 400 to 9
00 nm/min was obtained. As described above, according to this embodiment, by providing a mechanism for applying high-frequency power to three pairs of electrodes at the same frequency but with a phase difference of 120 degrees, plasma with good uniformity can be obtained, and the uniformity of etching can also be improved. It can be considered good. Furthermore, since there is almost no local deviation of the plasma, damage to the device such as destruction of the gate oxide film can be extremely reduced.

In this embodiment, the sample 3 to be etched is placed only on the electrode 42, but the sample 3 to be etched is placed on the electrode 44, 4
5 is equivalent to 42, and even if the samples are placed at 44 and 45 at the same time, etching proceeds in the same way, and the throughput can be improved.

A fourth embodiment of the present invention will be described below with reference to the drawings. FIG. 13 is a schematic diagram showing the structure of a dry etching apparatus according to a fourth embodiment of the present invention. In FIG. 13, 71 is a chamber, and 72 is an amplifier 7.
9. Temperature-controlled sample stage to which 50 MHz high frequency power is applied via a matching circuit 78; 73 is a ground electrode serving as a counter electrode; 74 and 75 are 300 MHz high frequency power applied via an amplifier 76 and a matching circuit 77; are the opposing electrodes to which is applied. The pressure inside the chamber is reduced to zero by a turbo pump (not shown) and a butterfly valve (not shown).
．． It is controlled to a predetermined pressure of about 1 Pa to 30 Pa. The sample stage 72 is the lowest temperature in the etching chamber and has a temperature of about 1
It is controlled within a range of 0 degrees to -10 degrees.

The difference from FIG. 1 is that there is one pair of electrodes to which 300 MHz high frequency power is applied. Also,
Electrodes 74 and 75 are placed outside the etching chamber via quartz or ceramic material to avoid corrosion due to etching and to prevent metal contamination from the electrodes.

The operation of the dry etching apparatus constructed as above will be explained below with reference to FIG. 13.

As mentioned in the first embodiment, the electrode 74
, 75 causes the electrons to vibrate and achieve high ionization efficiency despite being in a high vacuum.
High plasma density is obtained. In order to increase the ionization efficiency, it is desirable to apply a high frequency of 50 MHz or more, but the effect can be recognized even if the frequency is lower than that.

BCl3+Cl2, SiCl4+Cl2+
When applied to aluminum etching using a chlorine-based gas such as CHCl3, the electric field within the parallel plate electrodes is uniform, resulting in a highly uniform plasma.
Etching uniformity is also good. In this device, sample stage 7
By setting No. 2 to the lowest temperature in the etching chamber, the selectivity to photoresist could be increased to 5 or more. In addition, since there is almost no local deviation of the plasma, damage to the workpiece is extremely reduced.

The 50 MHz high frequency power applied to the sample stage 72 is used to form a bias for changing the energy of ions reaching the sample in order to control the selection ratio and the like. Therefore, the high frequency power is usually about several tens of watts, which is smaller than the high frequency power applied to the electrodes 74 and 75. Therefore, the amount of current flowing into the sample is only the amount required for etching, which is smaller than the amount required to maintain the plasma. Therefore, there is less damage caused by charge-up than when the sample stage is used as a high-frequency power supply electrode for maintaining plasma.

As described above, according to this embodiment, high-frequency power having a first frequency of 50 MHz or more is applied to a pair of electrodes, and the sample stage on which the sample to be etched is placed constitutes one of the electrodes. By providing a mechanism for applying high-frequency power of the second frequency to the pair of electrodes, a highly uniform high-density plasma can be obtained, and the plasma can also have good uniformity. Furthermore, since there is almost no local deviation of the plasma, damage to the workpiece can be extremely reduced.

[0045]

[Effects of the Invention] As described above, the present invention utilizes the phenomenon that electrons vibrate, rotate, or move in a cycloid under an appropriate high-frequency electric field, and utilizes the phenomenon that electrons vibrate, rotate, or move in a cycloid manner under an appropriate high-frequency electric field. A highly uniform plasma is used for etching. According to the present invention, it is possible to realize etching that has excellent microfabriability, high mass productivity, good uniformity, and extremely little damage to devices such as destruction of gate oxide films, and greatly contributes to the production of high-density semiconductor devices. Ru.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the structure of a dry etching apparatus in a first embodiment of the present invention.

FIG. 2 is a schematic diagram of trajectories projected onto a horizontal plane to explain the movement of electrons in the chamber of the dry etching apparatus in the same embodiment.

FIG. 3 is a characteristic diagram showing the frequency dependence of the distance traveled by electrons during one cycle.

FIG. 4 is a schematic diagram showing the relationship between phase difference and Lissajous waveform.

FIG. 5 is a schematic diagram showing magnetic flux distribution and electron rotation in a conventional magnetron etching apparatus.

FIG. 6 is a schematic diagram showing the rotation of electrons in the dry etching apparatus of the present invention.

FIG. 7 is a cross-sectional view and a magnetic field strength distribution diagram for explaining etching of boron phosphorus glass in a conventional magnetron etching apparatus.

FIG. 8 is a cross-sectional view for explaining etching of boron phosphorus glass in the dry etching apparatus of the present invention.

FIG. 9 is a diagram comparing the dry etching apparatus of the present invention and a conventional dry etching apparatus.

FIG. 10 is a schematic diagram showing the structure of a dry etching apparatus in a second embodiment of the present invention.

FIG. 11 is a schematic diagram of trajectories projected onto a horizontal plane to explain the movement of electrons in the chamber of the dry etching apparatus in the same example.

FIG. 12 is a schematic diagram showing the structure of a dry etching apparatus in a third embodiment of the present invention.

FIG. 13 is a schematic diagram showing the structure of a dry etching apparatus in a fourth embodiment of the present invention.

FIG. 14 is a schematic diagram showing a conventional reactive ion etching apparatus using magnetron discharge.

[Explanation of symbols]

1 Chamber 2 Sample stand 3 Wafer 4 Ground electrodes 5, 6 and 7 facing the sample stand
, 8 Electrode pairs to which 300 MHz high frequency power is applied 9, 10, 14 Amplifier 11 Phase lock mechanism

Claims (22)

[Claims] 1. A pair of electrodes and a sample stage are arranged around a plasma generation part in a vacuum chamber, a reactive gas for etching is introduced into the plasma generation part, and the electrode pair is provided with a sample stage in which electrons travel through the distance between the electrodes. Applying a first high-frequency power having a period shorter than the time required for oscillating electrons in the plasma generating section to generate plasma in the generating section, and transferring reaction products generated in the plasma onto a sample stage. A dry etching method characterized by etching a set sample by irradiating the sample. 2. A plurality of electrode pairs and a sample stage are arranged around a plasma generation part in a vacuum chamber, a reactive gas for etching is introduced into the plasma generation part, and high frequency power or a sample with different phases is applied to the plurality of electrode pairs. Applying harmonic high-frequency power to rotate electrons in the plasma generation section to generate plasma in the generation section, and irradiating reaction products generated in the plasma onto a sample placed on a sample stage; A dry etching method characterized by etching the sample. 3. The dry etching method according to claim 1, wherein the sample is etched by applying a bias to the sample stage. [Claim 4] Claim 3, characterized in that the DC bias is generated by applying AC power to the sample stage.
Dry etching method described. 5. The dry etching method according to claim 3, wherein after applying the first high frequency power to generate plasma, a bias is applied to the sample stage to etch the sample. 6. The dry etching method according to claim 1, wherein the sample is etched while controlling the temperature of the sample stage. 7. The dry etching method according to claim 6, wherein the temperature of the sample stage is set to be the lowest temperature in the etching chamber in which etching is performed. 8. The dry etching method according to claim 1, wherein the plasma is confined by applying a magnetic field. Claim 9: Claim 1, characterized in that an electronegative gas is used as the etching gas.
Or the dry etching method according to claim 2. 10. Etching gas includes SF6, Cl2, I
10. The dry etching method according to claim 9, wherein the dry etching method comprises a gas such as a halogen, a halogen compound, or oxygen, or a mixed gas containing any of them. 11. An electrode pair disposed around a plasma generation part in a vacuum chamber into which a reactive gas for etching is introduced, a sample stage, and the time required for electrons to travel the distance between the electrodes between the electrode pair and the electrode pair. The first high-frequency power source applies short-cycle high-frequency power, and the sample is placed on the sample stage, and the application of the high-frequency power causes electrons in the plasma generation section to vibrate and flow into the plasma generation section. generate plasma,
A dry etching apparatus characterized in that a reaction product generated in the plasma is irradiated onto a sample placed on a sample stage. 12. A plurality of electrode pairs and a sample stage arranged around a plasma generation part in a vacuum chamber into which a reactive gas for etching is introduced; A plurality of high-frequency power sources apply high-frequency power of waves, and the application of the high-frequency power rotates electrons in the plasma generation section to generate plasma in the generation section, and a reaction product generated in the plasma is collected as a sample. A dry etching device that irradiates a sample placed on a table. 13. The dry etching apparatus according to claim 11 or 12, wherein the electrode pair to which high frequency power is applied is not exposed to the vacuum in which etching is performed. 14. The dry etching method according to claim 11 or 12, wherein the electrode pair to which high-frequency power is applied is installed through quartz or ceramic material and is not exposed to the vacuum in which etching is performed. Device. 15. The dry etching method according to claim 11, further comprising a mechanism for applying a bias to the sample stage. 16. The dry etching apparatus according to claim 15, further comprising a mechanism for generating a DC bias by applying AC power to the sample stage. 17. The dry etching apparatus according to claim 15, further comprising a mechanism for applying a bias to the sample stage after a certain period of time has elapsed after generating plasma by applying high frequency power. 18. The dry etching apparatus according to claim 11, further comprising a sample stage temperature control mechanism. 19. The dry etching apparatus according to claim 11, further comprising a mechanism for applying a DC magnetic field approximately perpendicular to a plane of movement of electrons generated by high frequency waves. 20. The dry etching apparatus according to claim 12, further comprising a mechanism for measuring magnetic field strength generated from plasma and a mechanism for controlling high frequency power based on the magnetic field strength. 21. The dry etching apparatus according to claim 12, further comprising a phase lock mechanism that controls high frequency power having different phases to a constant phase difference. 22. The dry etching apparatus according to claim 12, further comprising a mechanism for applying a plurality of high frequency powers generated from the same signal source.