JP3519066B2 - Equipment for plasma processing - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to various plasma processes such as reactive ion etching (RIE),
The present invention relates to an apparatus used for performing plasma chemical vapor deposition (PCVD) or the like.

[0002]

2. Description of the Related Art In recent years, in order to advance various processes at a low temperature, plasma is generated in a depressurized container and various processes of an object to be processed such as a substrate of an integrated circuit are performed in the plasma atmosphere. Many device technologies have been developed. For example, various thin films of integrated circuits (conductive thin films such as Al, W and Ta, semiconductor thin films such as poly-Si and Si, or insulating thin films such as SiO ₂ , Si ₃ N ₄ ^and Al ₂ O ₃ ) are different. RIE (React
ive Ion Etching) method, other Al (CH ₃ ) ₃ , AlH
(CH ₃ ) ₂ etc. is used as a source gas, and this is
PCV in which Al (CH ₃ ) ₂ or Al (CH ₃ ) is decomposed and adsorbed on the substrate, and then Al is deposited by surface reaction
D film formation and the like.

The RIE method is a method of generating excited active species in a vacuum container, for example, CF ₄ F ₂ , CCl ₄ , C.
A gas such as l ₂ or CF ₂ Cl ₂ (hereinafter referred to as excited active species source gas) is introduced, direct current or high frequency power is applied to the susceptor as a holding means of the substrate to cause glow discharge to generate plasma, This is a method of causing ions generated in plasma and excited active species to act on the surface to be etched at the same time to perform physical and chemical etching. According to this method, a large selection ratio with the photoresist, which is a mask material, is maintained. However, anisotropic etching can be realized.

Even in glow discharge by high-frequency input, the substrate surface is negatively biased with respect to plasma in terms of direct current (this is called self-bias). Ions accelerated by the potential difference between this self-bias voltage and plasma potential. Collides with the surface of the substrate to etch the surface of the substrate by the action of the excited active species adsorbed on the surface of the substrate.

FIG. 12 is a schematic view of a cross-sectional structure of a typical reactive ion etching apparatus used conventionally. Reference numeral 503 is a substrate having a surface to be etched, for example, a semiconductor wafer or a substrate made of glass, quartz, metal or the like, and 504 is a susceptor electrode. High-frequency power is supplied to the susceptor electrode 504 via a matching circuit, and the vacuum container (chamber) 505 is normally grounded for safety. Here, as the high frequency power supply (RF power supply), it is usual to use one having an output frequency of 13.56 MHz. In many cases, a flat plate electrode is provided above the susceptor electrode 504 so as to face it.

In an actual apparatus, in addition to the above-described structure, an exhaust unit for vacuuming and exhausting gas in the vacuum container 505, a gas inlet into the vacuum container 505, a mechanism for taking in and out the substrate 503, and the like. Although it is provided, it is omitted in the figure for simplification of description.

The surface of the substrate 503 such as a semiconductor wafer or the like and the surface of the susceptor electrode 504 are negatively biased in direct current with respect to the plasma due to the RF power applied to the susceptor electrode 504, and ions accelerated by this voltage are generated. The surface to be etched of the substrate is etched by acting on the surface of the substrate and promoting the surface reaction.

[0008]

In the case of the above RIE apparatus, it is generally necessary to increase the plasma density by increasing the high frequency power when increasing the etching rate.

However, in the conventional device, when the high frequency power is increased, the self-bias of the electrode also increases,
At the same time, the plasma potential increases. As a result, the substrate has
Ions having large energy accelerated by the voltage having the large self-bias and the difference in plasma potential are irradiated. Therefore, the following problems occur.

When the irradiation ion energy becomes large, the resist is also etched, resulting in a change in the pattern dimension, and as a result, fine processing cannot be performed accurately. In particular, such a phenomenon is remarkable in future highly integrated devices in which the thickness of the resist is about 0.5 μm or less.

Since the ions having a large energy are irradiated, the underlying material is damaged, and the performance and reliability of the element made of such material is deteriorated. In particular, it causes serious troubles such as increase of leak current and deterioration of breakdown voltage.

Since the plasma potential is usually about +50 to 100 V, the ions determined by the plasma potential collide with the inner surface of the chamber, and this high energy ion collision causes the inner surface of the chamber to be sputtered and the chamber constituent material, For example, Fe, Ni, Cr, Cu, etc. contaminate the substrate surface. That is, the substrate surface contamination of the chamber constituent material due to high energy ion collision. If the substrate surface is contaminated with such heavy metals, defects will occur on the substrate surface in the next high temperature step or leakage current will be increased, which will significantly deteriorate the characteristics of the device.

In the conventional device, the high frequency power source has a frequency of 13.56 MHz.
When the plasma excitation frequency is low, such as 3.56 MHz, the DC self-bias generated at the electrodes becomes negative and large even when the gas pressure in the chamber and the high-frequency power are constant. Figure 7
Is the opposite electrode spacing of 3 cm, the disc electrode diameter 10c
³ shows current / voltage characteristics when m, Ar gas pressure was 5 × 10 ⁻³ Torr, and high frequency power was 50 W. In the figure, the horizontal axis is the DC negative voltage applied to the electrodes, and the vertical axis is the current flowing through the electrodes. The negative value of the current means that electrons flow into the electrode, and the positive current means that positive ions flow into the electrode. The negative voltage when the current is 0 corresponds to the electrode self-bias. This is because high-frequency power is normally supplied to the electrodes via the capacitors, and no direct current flows.

As can be seen from FIG. 7, the self-bias of the electrode is such that the frequency of high frequency power is 14 MHz, 40.6.
At 8MHz and 100MHz, -400V,
It becomes -260V and -90V. That is, even if the electrode structure, the gas pressure and the power are kept constant, the negative self-bias of the electrode becomes gradually smaller as the frequency becomes higher.

FIG. 8 shows the details. That is, the Ar gas pressure in the chamber is 7 × 10 ⁻³ Tor.
r, the high frequency power is 100 W, the electrode spacing is 3 cm, and the electrode diameter is 10 cm. When the high frequency of the plasma excitation high frequency power is changed from 10 MHz to 210 MHz, the self bias of the electrode is changed. The negative self-bias decreases sharply with increasing frequency. The plasma potential is also shown in FIG. 8 at the same time. This plasma potential has a frequency of 10 MHz.
Even if it changes from z to 210 MHz, it is maintained at almost + 20V.

As ultra-miniaturization and ultra-high integration of LSI progress,
The aspect ratio of contact holes and via holes gradually increases. That is, it is required to etch a thin and deep hole with good controllability and reproducibility.
Lower the gas pressure in the etching chamber (eg 10 ^-3 Tor)
It is necessary to increase the mean free path of the molecule by setting (r level). Even if the gas pressure is low, it is desirable that the frequency of discharge excitation is high in order to generate sufficiently high-concentration plasma and increase throughput. However, it is not desirable that the wavelength of the discharge excitation frequency be shorter than the diameter of the susceptor electrode 504. This is because a higher-order mode discharge is generated, plasma having a uniform density is not excited in the electrode, and uniform etching performance cannot be obtained.

That is, in the conventional apparatus, the plasma density, that is, the ion irradiation amount and the irradiation ion energy cannot be controlled independently and directly, and the pressure, flow rate, and high-frequency power of the excited active species source gas are not controlled. There is no choice but to indirectly control by appropriately combining such conditions.

Further, in addition to the above-mentioned RIE apparatus, as an apparatus which should be constructed so as to be able to process an object to be processed at high speed in plasma without damaging other than the object to be processed,
A PCVD device, an O ₂ plasma resist asher, a dry cleaning device and the like can be mentioned. Conventionally, these devices have been designed and produced individually, although they have common use conditions in their basic parts. At the same time, as mentioned above,
Had the drawback of.

The above problems have been found by the present inventor, and the present inventor has conducted diligent research to solve the above problems occurring in the conventional apparatus, and has found a solution.

According to the present invention, the substrate can be etched and the film can be formed on the substrate without damaging or contaminating the substrate (base), and the chambers, electrodes and the like have the same structure. By changing the gas to be introduced and the plasma excitation frequency, it can be applied to etching and film formation.
It is an object of the present invention to provide an apparatus for plasma processing which is excellent in productivity, low in cost and high in performance.

[0021]

SUMMARY OF THE INVENTION The present invention is a plasma processing apparatus configured to generate plasma in a depressurizable container and to process an object to be processed in the plasma. First and second electrodes that are provided to face each other and are formed in a flat plate shape, holding means for mounting an object to be processed on the second electrode, and the first electrode
Plasma having at least a first high frequency power source connected to the electrode, a second high frequency power source connected to the second electrode, and a gas supply means for introducing a desired gas into the container. In the process device, the first high-frequency power source is connected to the first electrode by a first inner conductor via a coaxial connector, and is also a hollow conical first outer conductor via the coaxial connector. And the first inner conductor and the first outer conductor are connected to the container by a second
It is a plasma device characterized by being connected by a first short circuit that short-circuits a high-frequency power source .

[0022]

For example, when used in an RIE apparatus, a substrate on which a thin film to be etched is formed as an object to be processed is mounted on a second electrode in a container, the inside of the container is decompressed, and a predetermined gas supply means is provided. A chlorine-based gas, a fluorine-based gas, a mixed gas thereof, or the like is introduced depending on the thin film to be etched. Then, the first electrode has a first frequency (100 to 2).
50 MHz) high-frequency power to generate plasma between the electrodes, and the second electrode is supplied with high-frequency power having a second frequency (10 to 50 MHz) lower than the first frequency to generate second plasma. Controls electrode self-bias. That is, the generated plasma density and the ion irradiation amount with which the substrate is irradiated are controlled by the high frequency power of the first frequency supplied to the first electrode.

On the other hand, the energy of the ions incident on the surface of the substrate is controlled by the self-bias of the high frequency power of the second frequency supplied to the second electrode. Since the high frequency power supplied to the first electrode plays a role of generating plasma, the power is usually large. However, since the frequency is increased, the negative self-bias of the first electrode can be made sufficiently small. Therefore, the ion energy applied to the first electrode is sufficiently small, the surface is not sputtered, and the substrate surface is not contaminated. Since the negative self-bias induced on the second electrode controls the ion energy with which the substrate surface is irradiated to an optimum value, problems of damage and contamination do not occur.

When used in a PCVD apparatus, a substrate on which a deposited film, which is an object to be processed, is to be formed is held on the second electrode. The magnitude relation between the first frequency and the second frequency is set in the same manner as in the case of the RIE apparatus, but the gas introduced into the container is, for example, Si film in the case of Si film formation.
H ₄ , SiH ₂ Cl ₂ , Si ₂ H ₆ , etc. are introduced, and in the case of SiO ₂ film formation, a mixed gas of SiH ₄ and O ₂ or Si ₂ H ₆ and O ₂ is introduced. Also in this case, damage to the substrate of the object to be processed and contamination of the object to be processed can be prevented for the same reason as described for RIE.

Furthermore, the conventional technique can be applied to a resist asher in which the problems of damage and contamination of the substrate surface are unavoidable. For example, a photoresist, which is indispensable for fine pattern processing, is usually stripped by a wet process using a mixed solution of H ₂ SO ₄ and H ₂ O ₂ , but when used as a mask material for ion implantation, high energy ion irradiation is performed. Since the resist is hardened in response to this, the resist cannot be peeled off in a normal wet process. Therefore, it is necessary to generate O ₃ and O radicals by using O ₂ plasma and remove the ion-implanted resist by utilizing ion energy.

When used as a resist asher, the R
As mentioned in the description of IE and PCVD, if the substrate is installed on the second electrode and the self-bias of the second electrode is controlled by the high frequency power of the second frequency, the resist is not damaged or contaminated on the substrate surface. Can be peeled off.

As described above, although there are some changes in condition setting during use, the present invention can be widely applied to various plasma process apparatuses.

[0028]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment in which the present invention is applied to an RIE apparatus for etching the surface of a substrate. Here, a case of etching a thin film formed on a semiconductor substrate will be described.

In the vacuum container (chamber) 105, an upper flat plate electrode 107 and a lower flat plate susceptor electrode 104 are provided.
And the vacuum container 105 are arranged so as to face each other.
Is made of metal and is connected to earth. Vacuum container 10
The inner surface of 5 is stable to plasma of corrosive gas such as fluorine or chlorine, that is, covered with oxide film, nitride film or fluoride film so as not to be corroded even when exposed to the plasma. There is. The electrode 107 includes a base material 102 made of a conductive material and a protective layer 101 formed on the surface of the base material 102 as a protective member made of SiO ₂ , Si ₃ N ₄ , Al ₂ O ₃ , AlN or the like. Has been done.

The protective layer 101 is for preventing the base material 102 from being etched by the plasma generated by the discharge, for example, Si, SiO ₂ , quartz, S.
_{iC, Si 3 N 4, Al} 2 O 3, made of AlN other materials. Alternatively, the passivation film may be made of a fluoride that satisfies a substantially stoichiometric ratio. This passivation film exhibits excellent etching resistance, and the passivation film may be formed, for example, as follows. That is, a base material (for example, a base material made of stainless steel, nickel, a nickel alloy, an aluminum alloy or other metals or alloys) is subjected to a high-purity impure process after finishing the surface to a mirror surface without a work-affected layer by electrolytic polishing technology or the like. Baking at a predetermined temperature in an active atmosphere to desorb adsorbed water. After baking, fluorinate with high-purity fluorine at a predetermined temperature, and after fluorination, heat treatment at a temperature slightly higher than the temperature during fluorination in a high-purity inert atmosphere, which satisfies a substantially stoichiometric composition ratio. A passivation film is formed on the base material.

If the protective layer 101 is made of Si, Si will be mixed into the substrate 103 on the susceptor electrode 104 even if the protective layer 101 is etched. Can be minimized.

A high frequency power supply 110 for outputting high frequency power of the second frequency f ₂ is connected to the susceptor electrode 104 via a matching circuit 108. In this embodiment, 100 MH
The example which supplies the high frequency electric power of z is shown. The second frequency f ₂ is preferably 10 to 50 MHz for controlling the potential of the susceptor electrode 104. Also, the electrode 1
07 through the matching circuit 109, the susceptor electrode 104
High frequency power supply 11 for outputting high frequency power of a _first frequency f ₁ which is a frequency higher than the frequency f ₂ supplied to the
1 is connected. In this embodiment, an example in which high frequency power of 250 MHz is applied is shown. Incidentally, as will be described later in detail, it is desirable that the _two frequencies f ₁ and f ₂ are not in an integral multiple relationship.

Further, the electrode 107 and the susceptor electrode 1
Each of the first high frequencies 04 (250 MH in this example).
z) and the second high frequency (100 MHz in this example) are input respectively so that the band eliminator (Band E)
liminator) 112 and 113 are provided. That is, the first high frequency f ₁ is short-circuited to the ground at the susceptor electrode 104, and the second high frequency f ₂ is shorted to the electrode 10.
Shorted to ground at 2. The band eliminator 11 used for the electrodes 107 and 104.
2, 113 may basically have a configuration such as the tank circuit 102b shown in FIG. A parallel circuit of L _1, C _{1 is, f 1 = {1 / 2π} (L 1 C 1) 1/2} impedance becomes maximum at the resonant frequency of the (Figure 3), for the other frequency, most Since a short circuit occurs, only a high frequency having a predetermined frequency (f ₁ = 250 MHz in this case) can be selected and supplied to the electrodes.

It is needless to say that the configuration shown in FIG. 2 shown here merely shows the basic principle, and various modifications may be added. For example, FIG. 4 is an example of the improvement.

The circuit 102b has an inductance L₁To
It is grounded via DC, but this is DC
If you want to make a floating state, for example,
Capacitor C like 102d_sTo add the DC component
Just cut it. In this case, the resonance frequency of the circuit 102d
Number is frequency f₁C to keep_sThe value of f₁・ L₁ ≫ 1 / f₁ C_s It must be large enough to satisfy

In this case, f ₀ = {1 / 2π (L
_With respect to the frequency of ₁ C _s ) ^1/2 }, the impedance of the series circuit of L ₁ and C _s becomes 0, and a short circuit occurs with respect to the high frequency of frequency f ₀ . By setting the frequency f ₀ equal to the frequency f ₂ applied to the susceptor electrode 104, it is possible to effectively prevent the high frequency of the frequency f ₂ from being superposed on the electrode 107. That is, even if the electric field of the high frequency power entering the susceptor electrode 104 terminates vertically from the susceptor electrode 104 to the electrode 107, the electrode 107 is short-circuited to the ground for the high frequency of the frequency f _2. 107
Does not change with the power of frequency f ₂ .

Although the band eliminator 112 has been described above, if the band eliminator 113 has a similar structure, the voltage of the susceptor electrode 104 does not fluctuate due to the frequency f ₁ supplied to the electrode 107. That is, in the circuit of FIG. 4, the inductance L ₁ is the inductance L ₂ , the capacitor C ₁ is the capacitor C ₂ , the capacitor C _S is the capacitor C _S2 , and f ₂ = 1 / 2π (L ₂ C ₂ ) ^1/2 , f ₂ L ₂ >> 1 / f ₂ C _S2

Further, f ₁ = 1 / 2π (L ₂ C _S2 ) ^1/2 .

Discharge of the excited active species source gas introduced into the vacuum chamber 105 in order to generate ions that form plasma is performed at a high frequency of frequency f ₁ . Increasing the power of the frequency f ₁ to increase the ion density does not affect the voltage of the susceptor electrode 104.

The same applies to the high frequency power of frequency f ₂ supplied to the susceptor electrode 104. Even if the high frequency power of the frequency f ₂ is changed, the power of f ₂ is
This is because at 7 it is shorted to ground.

An example thereof is shown in FIG. 5, in which the distance between the first electrode and the second electrode is 3 cm, the diameter thereof is 10 cm, and the gas pressure is 7 × 10 ⁻³ Torr. ,
f ₁ = 100 MHz, the input power is kept constant at 150 W, and f ₂ = 30, 40, 50 MHz, and the power is varied, the DC self-bias of the first electrode and the second electrode is plotted. ing. The self-bias of the first electrode is unaffected by the frequency and power delivered to the second electrode at about -25V. The potential of the second electrode is about 10 V when there is no high frequency input, but decreases linearly as the high frequency power of the frequency f ₂ increases, and becomes a negative voltage above a certain power. The lower the frequency f _{2, the} larger the change in self-bias voltage for the same change in power. In any case, it is clear from FIG. 5 that the DC potential (self-bias) of the electrodes can be controlled by the high frequency power and its frequency without affecting the potentials of the opposing electrodes at all.

With the above-described structure, it is possible to effectively prevent the high frequency supplied to the other from overlapping the electrode 107 and the susceptor electrode 104, and to supply only the high frequency to be supplied to each. Therefore, it is possible to easily and accurately control the self-bias plasma density and the energy of the irradiated ions.

A magnetic field approximately parallel to the surface of the electrode 107 is generated by the cylindrical magnet 106 provided on the back surface of the electrode 107, and the electrons are attracted to this magnetic field to perform cyclotron motion. When a vertical high frequency electric field is present between the electrodes 107 and 104, energy is effectively applied to the electrons that move in the cyclotron, and the high frequency power effectively generates high density plasma. Therefore, in this device,
The electric fields of the two input high-frequency powers are set to be almost perpendicular to the susceptor electrode 104 and the electrode 107, respectively.

Numeral 106 is a permanent magnet for magnetron discharge. In practice, an electromagnet using a ferromagnetic material is preferable. Further, the apparatus is provided with an exhaust unit for drawing a vacuum in the vacuum container 105, a mechanism for introducing gas, and a mechanism for taking in and out the substrate 103, but these are omitted for simplification of description.

Unlike the conventional device, the device of this embodiment is provided with the electrode 107 in addition to the susceptor electrode 104. Therefore, a high-frequency plasma having a high power is supplied to the electrode 107 to generate high-density plasma. It can be generated, which in turn enables high speed etching. However, if a high-frequency power having a large electric power is supplied to the electrode 107, the self-bias becomes large and the electrode may be sputter-etched. In order to prevent such etching, the frequency f of the high frequency power supply 111 supplied to the electrode 107 is
₁ is set to be higher than the frequency f ₂ to reduce the self-bias (the self-bias is reduced as the frequency is increased. See FIG. 8), and the protective layer 101 is provided on the surface of the base material 102 of the electrode 107.

On the other hand, the self-bias generated in the susceptor electrode 104 is caused by the high frequency power source 110 as shown in FIG.
Can be controlled by the power and frequency of
Taking into consideration the material of the thin film to be etched, the high frequency power source 11
The power and frequency of 0 may be selected and supplied to the susceptor electrode 104.

After all, if the apparatus of this embodiment is used, the electrode 1
A high density plasma is generated by the high frequency power supplied to 07 (plasma density, that is, the ion density is controlled by the power), and the ion energy irradiated to the substrate surface is supplied to the susceptor electrode 104 at a frequency f ₂ of Since the desired value can be controlled by high-frequency power, high-speed RIE can be performed while preventing damage to the substrate 103 and the like.
Will be able to do.

Next, the electrode 107 and the susceptor electrode 10
The influence of the high-frequency power supplied to No. 4 and the frequency will be described.

FIG. 6 shows an electrode 10 using the apparatus shown in FIG.
4 shows a circuit configuration for measuring the current and voltage characteristics of FIG. High frequency filter 203 connected to the electrode 104
Is, for example, the band eliminator 102b shown in FIG.
As described above, the impedance is high only at the frequency f ₂ of the high frequency supplied to the susceptor electrode 104, and the frequency is deviated from the high frequency. A DC power supply 201 and an ammeter 202 are connected in series. A capacitor 206 is connected in parallel at the connection point between the high frequency filter 203 and the ammeter 202 in order to short-circuit the DC power supply 201 and the ammeter 202 in terms of high frequency.

In such a state, for example, Ar gas is introduced into the vacuum chamber 105 at a pressure of 5 × 10 ⁻³ Torr and 50 W.
FIG. 7 is a graph showing the relationship between the DC voltage V applied to the electrode 104 and the resulting flowing current by causing the discharge with the high frequency power of. In this case, the frequency of the high frequency power supply 110 is variable, for example, 14 MHz, 40.68 MHz and 1 MHz.
The frequency is changed to three frequencies of 00 MHz. Note that the current in which the ions having a positive charge flow into the electrode 104 has a positive value.

For example, looking at the characteristic of 100 MHz, when the DC voltage V is about -95 V (this value is the self-bias voltage _VSB ), the DC current I = 0 and V> _VSB.
I <0, and V < _VSB , I> 0. The self-bias voltage V _SB is a DC bias voltage generated when the electrode 104 is subjected to high frequency discharge in a floating state. That is, when the electrode 104 is at this potential, the numbers of ions and electrons flowing from the plasma to the electrode 104 become equal to each other, and therefore they cancel each other out and the direct current is zero.
Becomes

On the other hand, when the potential of the electrode 104 is controlled by the DC bias voltage applied from the outside, a current flows. For example, between the DC voltage V and the self-bias voltage V _SB ,
When the relationship of V> _VSB is established, more electrons flow in and I <0.

On the other hand, in the case of V < _VSB , the potential barrier for electrons increases and the number of electrons flowing in decreases, so that the ion current becomes larger and a positive current flows. Further, if the DC voltage V is increased to the negative side, V =
At V ₀ , the current value saturates and becomes almost constant. This is equal to the current value of ions only.

From the above, I near V = V _SB
The slope of the −V characteristic curve corresponds to the width of the energy distribution of electrons. That is, a large slope means that the width of the electron energy distribution is narrow. As is clear from FIG. 7, the energy distribution at 100 MHz is about 1/10 smaller than that at 14 MHz.
On the other hand, when the width of the energy distribution of ions is ΔE _ion and the width of the energy distribution of electrons is ΔE _e , there is a substantially proportional relationship between the two, so the width of the energy distribution of ions is also about 1 /. It can be said that the number has decreased to 10.

Further, although the value of V _SB is the same high-frequency power of 50 W, it is 10 with respect to −400 V at 14 MHz.
At 0 MHz, it is about -95 V, which is smaller than 1/4 or less in absolute value. When the power is reduced to 5 W with 100 MHz discharge, the value of _VSB is reduced to -25V. That is, the self-bias can be controlled in a wide range by controlling the frequency and the power.

In the conventional RIE method, the underlying substrate is damaged and the device characteristics are deteriorated. This is for the following reason.

In the conventional example, the electrode 107 is set to a low frequency 1
Since it was discharged at 3.56 MHz, | V _sub | = 4
The voltage was 00 V to 6000 V, and the ions accelerated by this high voltage collided with the substrate.

However, in the first embodiment of the present invention, since the electrode 107 is discharged by using a high frequency of 250 MHz, Δ compared with the conventional case of 13.56 MHz.
E _ion can be made as small as 1/20 or less. In the device of the present invention, the discharge is the frequency f ₁ applied to the electrode 107.
Of the high frequency power, thereby generating a high density plasma and supplying a frequency f ₁ (2) higher than the frequency f ₂ supplied to the susceptor electrode 104.
50 MHz), the width of distribution of ion energy in the generated high density plasma is small (the number of ions having energy different from the average energy value is small). Further, as will be described later, since the magnetic circuit is designed so that the magnetic field strength in the direction parallel to the electrodes is as strong as possible, the self-bias voltage is -30 V or less at the input of high-frequency power of 50 W, and the plasma The density is improved by about 10 times or more. According to FIG. 5, since the high frequency power is 100 W and the self-bias is about −10 V at f ₁ = 210 MHz, f ₁ = 250 MHz
Then, the self-bias is -5 V or less.

Since the self-bias of the electrode 107 is as low as -5 V or less and the protective layer 101 is provided, the base material 102 of the electrode 107 is not sputtered at all. Therefore,
It is extremely easy to control the high frequency power or frequency f ₂ applied to the susceptor electrode 104 to such an extent that the self-bias does not damage the substrate, and the frequency f ₁ is controlled so as to obtain a desired etching rate. If the power is set to 1, the ion with high energy that damages the substrate surface will not be irradiated, and etching with high speed and high selectivity can be achieved without causing damage to the thin film, resist film or underlying substrate. It becomes possible to do.

That is, the self-bias voltage V _SB becomes lower as the frequency of the high frequency power supply becomes higher and as the high frequency power becomes smaller. Therefore, the frequency and the power may be selected to be supplied to the susceptor electrode 104 so that the ion energy and the ion irradiation amount required for high-speed etching are obtained without damaging the quality of the thin film or the base substrate.

On the other hand, the electrode 102 has a frequency of 250M.
Since a high frequency power of Hz is applied, a small self-bias voltage is generated, and since the protective layer 101 is formed, the base material 102 can be prevented from being etched. Further, in the embodiment shown in FIG. 1, the permanent magnet 106 is mounted, which allows the magnetron discharge (electrons are wound around the lines of magnetic force and cyclotron moves while receiving energy from the high frequency electric field to cause neutral excitation) in the vicinity of the electrode 107. (Effective ionization of active species source gas molecules) occurs, the ion concentration is increased, and the etching rate can be further increased.

As described above, according to the two-frequency excitation RIE apparatus of the present invention, it is possible to etch a high-quality thin film or substrate without damaging the substrate with a high selection ratio while maintaining a high etching rate. It was

Further, as shown in FIG. 6, the susceptor electrode 10
It is also possible to control the energy of the ions flowing into the susceptor electrode 104 by applying a DC bias voltage to 4. The method of applying the DC bias voltage to control the potential of the susceptor electrode 104 and consequently controlling the surface potential of the substrate is effective when the thin film to be etched or the substrate (base) is a conductive material.

As described above, the electrode 107 and the susceptor electrode 104
The frequency of high frequency power supplied to the
Although only the case of setting the frequency to 50 MHz has been described, it goes without saying that the frequency selection is not limited to this.

In short, in the case of the RIE device, the electrode 107
The first frequency f ₁ supplied to the susceptor electrode 104 may be higher than the second frequency f ₂ supplied to the susceptor electrode 104.
The actual value differs depending on the purpose, and may be determined in consideration of the etching rate that should be required, the coating shape of the formed film at the step portion, and the like. Further, the material to be etched is not limited to the insulator, but may be a conductive material.

The magnet 1 installed on the back surface of the electrode 107
06 is not limited to the configuration shown in FIG. For example, FIG. 9 shows a second embodiment of the present invention,
In the case of the present embodiment, a strong racetrack magnet 409 is provided and scanning is performed in order to improve the uniformity of the magnetic field. In this case, the scanning system 410 of the magnet 409 is connected to the vacuum container 1
If it is provided outside 05, it is convenient to prevent the reaction system from being contaminated by dust generated by mechanical operation.

Further, a magnet may be installed on the side of the susceptor electrode 104 to improve the efficiency of RIE. Further, the magnet used here may be mounted stationary like the magnet 106 shown in FIG. 1, or may be movable like the magnet 409 mounted to the scanning system 410. I don't care.

Further, the damage to the substrate 103 is further reduced.
To do this, for example, the following method can be used.
It For example, formed on the surface of the substrate 103 such as Si
SiO ₂When etching an insulating film such as
While the film of about m is formed, the susceptor electrode 104
The RF power supplied is increased to etch at high speed,
Just before the surface of the plate 103 begins to be exposed, the RF power is reduced.
It is a method of switching. This will expose the substrate 103
Etching in a sufficiently low self-bias state after starting to put it out
Damage to the substrate surface is almost zero because
It is possible.

If the kinetic energy of the ions irradiating the surface of the substrate 103 is too large, any material will be damaged. The material begins to be damaged when the kinetic energy of the irradiated ions becomes slightly larger than the critical energy of damage generation determined by the interatomic bond strength of each material. The interatomic bond strength of an insulator is usually larger than that of a semiconductor. The energy of the irradiation ions may be determined in consideration of the properties of the substrate 103 and the material of the insulator.

FIG. 10 shows a third embodiment of the substrate 1.
No. 03 damage to the surface of the substrate 103 can be eliminated, and the energy of the ions irradiated onto the surface of the substrate 103 can be freely selected. The difference from the first embodiment shown in FIG. 1 is that two different frequencies f ₂ and f ₃ can be switched and input to the susceptor electrode 104. The band eliminator 401 is also modified and configured. Reference numerals 402 and 403 denote LC resonance circuits having resonance frequencies of f ₂ and f ₃ , respectively.

F ₂ = 1 / 2π (L ₂ C ₂ ) ^1/2 f ₃ = 1 / 2π (L ₃ C ₃ ) ^{1/2 The} band eliminator 401 in which two resonance circuits 402 and 403 are connected in series is Since the impedance is large only for two frequencies f ₂ and f ₃ , and the frequency is short for other frequencies, these 2
Susceptor electrode 104 selectively only for high frequency
It has a function to supply power to.

For example, f ₁ = 250 MHz and f ₂ = 1
00 MHz and f ₃ = 40 MHz. Then, for example, while the initial film of about 0.5 to 1 μm is formed, the frequency of the high frequency applied to the susceptor electrode 104 is f
_{At 3} (40 MHz), the self-bias becomes as large as 0 to −100 V as shown in FIG. 5, and a large etching effect can be obtained. When the surface reaches about 100 Å, the frequency is switched to f ₃ (100 MHz) to etch a thin film (for example, 10 Å to 100 Å). In this way, when the surface of the substrate starts to be exposed, ions are irradiated on the surface of the substrate with a small self-bias value (about -10 to -20 V) corresponding to 100 MHz, so that the substrate is hardly damaged.

Such a method becomes particularly important when controlling the flatness of the surface shape of the thin film deposited by the RIE method. This is because the energy of the most effective etching ions can be controlled by changing the frequency, and the energy can be selected at an optimum energy value without causing damage to the substrate 103.

Here, f₂, F₃Two different frequency fields
Although only the case was described, for example, f ₂, F₃, F_FourSay
Needless to say, three values may be used. However
In this case, the frequency f to be applied first_FourIs f_Four> F₂，
f₃As the later, the damage with the highest frequency is used
Is important to be small.

When a plurality of frequencies are used, these are frequencies f ₁ for discharge excitation. Including f ₁ , f ₂ , f ₃ ^, ...
・ ・ It is desirable to select so that they are not in a relationship of harmonics. The discharge space is non-linear and therefore f ₁ , f ₂ , f ₃ ,
This is because the harmonics of ... May be superimposed in a completely different state depending on the discharge conditions, and the setting of the conditions may not be unique.

The resonance circuits 402 and 4 in FIG.
If the resonance circuit shown in FIG.
Can have an effect. However, in FIG. C_S ≫ C₂ , C₃ And need to.

Next, the concept of high performance common to various processes, which is a basic component of the above-mentioned RIE apparatus and is performed by forming plasma between the parallel plate electrodes facing each other, will be described.

The requirements for improving the performance of the discharge plasma process are (1) no damage (damage) to the substrate surface, and (2) no contamination of the substrate surface due to sputtering of the vacuum container or electrode material. It is a requirement. Of course, in addition to the above, there is a need for specific etching and film deposition performance enhancements, such as high-speed etching and high-speed film formation, and the realization of high-density plasma with as little high-frequency power as possible. Nor.

To meet the requirements (1) and (2)
Is the plasma potential of the plasma formed by the discharge,
Do not sputter the vacuum container or electrode material
That is + 30V or less, preferably + 20V or less
Is required. The vacuum vessel is normally used with being grounded.
Energy of the ions incident on the inner surface of the vacuum container
Has an energy of about the plasma potential. Electrode 102
The susceptor electrode 104 is usually supplied with high frequency power.
Since a negative voltage is applied in terms of direct current, ions with a positive charge
Is incident, but its energy has the desired purpose.
It is controlled by the energy value you have. Either way,
Plasma potential formed between opposite electrodes is about +5 to + 20V
It is indispensable to be kept within a range of degrees
It The energy of the individual ions that irradiate the substrate surface
Depends on the substrate surface material depending on the purpose of etching and film formation.
Then, each has an optimum value. Individual ion energy
The optimum value for each material is the susceptor.
The frequency f supplied to the electrode 104 ₂Adjust the high frequency power of
Then, the self-bias voltage of the susceptor electrode 104 −V
_s(V) to V_OP= V_P + V_S And set it so that
Yes. Ions must collide between the plasma and the substrate surface
For example, the ion energy irradiated to the substrate surface is
This is because it is determined by the potential difference of the substrate surface potential.

Where V _{OP is} the optimum irradiation potential of ions, V
_P: plasma potential, -V _S: a self-bias of the susceptor electrode.

The above setting conditions can be applied only when the potential of the plasma formed between the opposing electrodes is suppressed to a low positive voltage. That is, V _P <V _OP must be established. This is because the self-bias realized by applying high frequency power to the susceptor electrode 104 always acts in the negative voltage direction. Therefore, V _SP > V _P , V _OP > V
_P Plasma potential V _P to but as satisfied, low positive voltage
Is set. However, V _SP is the sputtering start voltage of the vacuum container and the electrode material.

In conclusion, in order to improve the performance of the plasma application device, the plasma potential should be set to a low positive voltage (V _SP > V _P). , V
_OP ＞ V _P ). The reason why the plasma potential becomes high at a positive voltage is that electrons with a negative charge, whose mass is lighter than that of an ion, escape from the plasma space, the ions with a positive charge become excessive, and the plasma has a positive charge. Depends on having. In other words, in order to keep the plasma potential at a positive low potential, it is necessary to prevent electrons from escaping from the plasma space as much as possible. At the same time, it is important that high-frequency power causes discharge and ionization as effectively as possible.

Next, the DC magnetic field distribution and the high frequency electric field distribution that realize such conditions will be described with reference to FIG. FIG. 13A shows a DC magnetic field distribution 601 (dotted line) with respect to the flat plate-shaped electrode 107 and the susceptor electrode 104 facing each other.
A high frequency electric field distribution (solid line) 602 is shown. FIG. 13A shows an example of an ideal state. That is, a DC magnetic field exists in parallel to the electrode plates of the electrodes 107 and 104 facing each other, and a high-frequency electric field exists vertically between the electrode plates. The electrons existing between the polar plates are wound around the DC magnetic field and make a circular motion (cyclotron motion). Since a high frequency electric field exists in the moving direction of circularly moving electrons, energy is efficiently converted from the electric field into the movement of electrons. The electrons that have gained energy are confined by cyclotron motion between the plates, so they efficiently collide with neutral molecules and atoms and ionize them. The electrode 107 and the susceptor electrode 104 are normally supplied with a negative voltage due to high frequency input. Therefore, electrons with negative charges do not enter both electrodes. Therefore, the electrons are confined between the two electrodes in the vertical direction. However, since the ends of the two electrodes in the parallel direction are simply spaces, electrons flow out from the ends. In order to suppress the escape of the electrons in the lateral direction, the intensity of the DC magnetic field B may be distributed as shown in FIG. That is, the strength of the DC magnetic field B is made constant with respect to the distance r from the center of the electrode plate to the vicinity of the end of the electrode plate, and the magnetic field strength is increased near the end. As a result, the electrons are reflected in the portion where the magnetic field strength is strong and are confined in the constant magnetic field strength portion.

FIG. 14 shows a fourth embodiment to which the concept shown in FIG. 13 is applied. The same components as those of the first embodiment shown in FIG. 1 are designated by the same reference numerals and duplicate explanations will be omitted.

Frequency f for exciting discharge between electrodes
The high frequency power of ₁ is supplied through the coaxial connector 710. Reference numeral 716 is an inner conductor that guides high-frequency power to the electrode 102, and reference numeral 712 is an outer conductor of the coaxial cable formed in a tapered shape, which is connected to a metal vacuum container 105 made of Al alloy, stainless steel, Ti, or the like. In the first embodiment shown in FIG. 1, the DC magnetic field is formed by the permanent magnet 106, but in the second embodiment shown in FIG. 14, it is formed by the electromagnet. Reference numeral 715 is a magnetic body having a high magnetic permeability μ and a high saturation magnetic flux density, which constitutes an electromagnet, and 714 is an electric wire for supplying a direct current. Since the electromagnet is completely surrounded by the inner conductor 716 and the electrode base material 102, it is not exposed to an electric field or magnetic field having a high frequency f ₁ .

High frequency power of frequency f ₂ for controlling the self-bias of the susceptor electrode 104 is supplied via the coaxial connector 711. 717 is an inner conductor of the coaxial cable, 7
Reference numeral 13 is an outer conductor. The series circuit of the inductance L ₁ and the capacitor C _{1 and} the series circuit of the inductance L ₂ and the capacitor C ₂ are circuits for short-circuiting the high frequencies of the frequencies f ₁ and f ₂ , respectively.

Reference numerals 708 and 709 denote insulator substrates forming these short circuit circuits, which are made of, for example, Teflon (registered trademark) impregnated insulator. Inner conductors 716 and 717 and outer conductor 71
The circuit for short-circuiting 2,713 is formed in a conical shape so as to fit the cylindrical coaxial configuration. FIG. 15 (a),
(B) shows an example of the short circuit. The short-circuits 1 and 2 are provided with holes 805 and 806 for inserting the inner conductors 716 and 717 in the central portion, and the substrate is formed in a disk shape by a Teflon-impregnated insulating material. The example shown in FIG. 15 shows an example in which four series resonant circuits are radially arranged at an angular interval of 90 degrees. 801, 803
Is an inductance, and 802 and 804 are high frequency capacitors such as monolithic ceramics. The shaded area is the Cu thin film left on the insulating substrate. The thin film is usually 35 to 7
The thickness is about 0 μm. The thickness of the insulator substrate is about 1 to 3 mm, depending on the high frequency power. FIG. 15 (a)
Then, as the inductance 801, an inductance having a straight line is used, and the capacitor is a chip capacitor. In FIG. 15B, a coil formed by winding an electric wire a required number of times is used as the inductance 803, and a plate capacitor is used as the capacitor 804.

Description will be returned to FIG. In order to efficiently confine high-frequency power, particularly power having a frequency f ₁ that forms a discharge between the electrodes, the electrodes 102 and the susceptor electrode 104 are made of insulating ceramics 706 and 707.
Each is configured so as to float from the vacuum container 105.
The distance from the electrode to the vacuum container is farther than that of the electrode. This is for almost terminating the electric field of the high frequency power having the frequency f ₁ incident on the electrode 102 on the susceptor electrode 104. The high-frequency current of frequency f ₁ terminates in the susceptor electrode 104, and then flows out to the outer conductor 712 via the inner conductor 717, the short circuit (L ₁ , C ₁ ), and the vacuum container 105.

The electrode interval usually depends on the gas pressure, but is usually 2 to
It is about 10 cm. Since the electrode area is set larger than that of the substrate 103, if the diameter of the wafer as the substrate 103 is 6 inches, 8 inches, and 10 inches, at least the diameters of the electrodes should be larger than 20 cm, 25 cm, and 30 cm, respectively. There is a need.

FIG. 16 shows the fifth embodiment, which is relatively close to the actual structure. In the case of this embodiment, since the distance between the electrodes 107 and 104 is narrow, most of the high frequency electric field is confined between the opposing electrodes.

The frequency f supplied to the susceptor electrode 104
If the short circuit to the high frequency power of ₁ is insufficient,
As in the sixth embodiment shown in FIG. 7, a short circuit may be directly provided between the susceptor electrode 104 and the vacuum container 105. The main point of the configuration of this embodiment is that a magnetic field as strong as possible is provided between two electrodes facing each other.

As in the embodiment shown in FIGS. 16 and 17, in the case of an electromagnet composed of the coil 722 and the magnetic body 715, the distribution of magnetic force lines thereof is a distribution which spreads downward as shown in FIG.

As in the seventh embodiment shown in FIG. 19, if superconductors or superconducting thin films 731 and 732 exhibiting complete diamagnetism are provided on the back surfaces of both electrodes 104 and 107, respectively.
Since the magnetic lines of force do not leak to the outside of the superconductors 731 and 732, they are present only between the electrodes.

When it is necessary to cool the substrate 103,
For example, by coating the back surface of the electrode with an oxide superconductor that exhibits a superconducting phenomenon at a liquid nitrogen temperature by sputtering film formation of about 1 μm or more, an extremely large magnetic field confinement effect can be produced. The eighth embodiment shown in FIG. 20 shows such a magnetic field confinement effect.

Similarly, in order to confine a magnetic field between both electrodes and generate a strong parallel magnetic field, electromagnets (721, 723) are similarly provided not only on the electrode 102 side but also on the susceptor electrode 104 side. Good. FIG. 21 shows a ninth embodiment constructed on the basis of this principle. Electromagnets (715, 722), (721, 723)
Are both inner conductors 716 and 717 for supplying high frequency power.
Is substantially surrounded by. An electric wire for supplying a current to the coils 722 and 723 passes through the inner conductors 716 and 717 and is drawn to the outside.

In the ninth embodiment, the electrodes 102, 1
It is even more preferable if 04 is coated with a perfect diamagnetic superconductor. In this embodiment, in the vacuum container in which the discharge plasma is formed, the container bodies 706 and 707 are made of ceramic, and the outer container 105 ′ is made of metal. The outer container 105 'plays a role of supplying a ground and a high frequency current. With this configuration, the first, ninth, and first
The discharge between the electrode 102 and the vacuum vessel found in the apparatus of each embodiment shown in FIG.
Almost all of them are confined between 104, and high-density plasma can be formed between the electrodes with a small amount of high-frequency power.

It goes without saying that the electromagnet surrounded by the inner conductors 716 and 717 may be formed of a permanent magnet. The material that constitutes a permanent magnet usually has a low relative magnetic permeability.
~ 5 or less.

Therefore, in the ninth embodiment shown in FIG. 21, the coils 722 and 723 are removed and the first embodiment shown in FIG.
The donut-shaped perfect diamagnetic superconductor 75 as in Example 0
It is good to insert 1,752. In this case, the superconductor 75
Magnetic bodies 715 and 721 in which 1,752 are fitted are made of permanent magnets.

The RIE apparatus, which completely suppresses the sputter contamination of the chamber material and does not damage the substrate at all, has been described above. The gas introduced into the vacuum chamber varies depending on the material to be etched, and the chlorine-based ( Cl ₂ , Si
Cl ₄ , CH ₂ Cl ₂ , CCl _4, etc.), fluorine-based (F ₂ , C
H ₂ F ₂ , CF ₄ , SiF _4, etc. and mixed gas system (CF ₂
Cl ₂ or the like) is used, and carrier gases Ar and He and additive gases H ₂ and O ₂ are added.

From the standpoint of uniform etching, it is required that the wavelength of the output frequency f ₁ of the high frequency power source used for high frequency discharge is at least larger than twice the diameter of the wafer. Desirably, the frequency f ₁ is 100 MHz (wavelength 3 m) to 1 G
Hz (wavelength 30 cm).

However, for example, when a microwave such as 2.45 GHz is used, the wavelength of the electromagnetic wave becomes smaller than the wafer diameter as the substrate, which may cause variations in the etching amount, which is preferable. Absent.

Although the embodiments of the present invention have mainly been described with respect to etching of SiO ₂ and Si films, the present invention is not limited to this. For example, PSG film, BPSG film,
ASG film, silicon nitride film, Al ₂ O ₃ film, AlN film, A
It may be used for etching films and substrates made of 1, W, Mo, Ta, Ti or alloys thereof.

The excited active species source gas may be appropriately selected according to the type of thin film to be etched. For example, poly−
In the case of a Si thin film, Cl ₂ , CCl ₄ , CCl ₂ F ₂ , Cl ₂
Etc., in the case of Si thin film, Cl ₂ , CCl ₂ F ₂ , CF ₄ etc .; in the case of SiO ₂ thin film, CF ₄ / H ₂ , C ₂ F ₆ etc., A
In the case of a 1 thin film, CCl ₄ , SiCl ₄ , BCl ₃ , Cl ₂ or the like may be used, and in the case of a Mo thin film, W thin film, Ti thin film, Ta thin film or the like, F ₂ , Cl ₂ , CF ₄ or the like may be used appropriately. In addition, H ₂ ,
It is also effective to add O ₂ and N ₂ as additive gas.

The substrate 103 on which these are formed is also
The material is not limited to an insulating material, but may be a conductive material or a semiconductor.

Further, it goes without saying that the present invention can also be applied to etching of a polymer material such as a polyimide film or a resist. Needless to say, the substrate to be etched is not limited to the semiconductor wafer. Also,
It can also be used for sputter etching other than reactive ion etching.

Next, the apparatus having the configuration of each of the above-mentioned embodiments is not limited to the above-mentioned RIE, but PCVD, dry cleaning,
It can be easily used for resist ashing, dry development of resist, etc. by changing a part of the use conditions.

First, plasma CVD (PCVD) is performed.
However, for Si film formation, SiH_Four, Si₂H₆, SiH₂Cl₂
Or other source gas such as Ar, He, H₂Etc.
Gas is added, and H is used for Al film formation.₂+ Al (CH₃)₃，
H₂+ AlH (CH₃)₂Gas such as SiO₂For film formation,
SiH_Four+ O₂, SiH₂Cl₂+ O₂, Si₃N_FourDeposition
To SiH_Four+ NH₃+ H₂Gas is supplied. First
1, 7, 9, 10, 12, 14, 15 Examples shown in FIGS.
Then, the raw material gas is supplied to the high frequency power source₁Discharge by
Put into plasma state. High-density plasma is formed between the electrodes
However, the high frequency f₁Is kept high at 150-250MHz
Self-bias appearing on the electrode 102 because it is leaning
Is as low as -10 to -2V, and the electrode is not sputtered.
Absent. In addition, the substrate surface irradiation ion energy necessary for film formation
Guy is f₁Lower frequency f₂(For example, 10-80M
It is controlled by high frequency power of (Hz). Irradiation ion energy
Is the optimum value f required for film formation.₂Controlled by the power of
The irradiation ion density is f₁Controlled by the power of. example
For example, in the case of Si film formation, (Ar + SiH_Four) Supply
Suppose Ar and SiH_FourIt is possible to adjust the mixing ratio of
is important. Especially at low temperature from room temperature to about 400 ℃,
In order to form a high-quality Si film, Si by ion irradiation is used.
This is because the activation of the surface is the deciding factor. For example, 1
While the number of Si atoms is in the regular lattice position, the optimum
If the number of irradiated ions with energy is usually 1 or more,
Because it is necessary. For example, 10 Si atoms
Ion irradiation or 50 ion irradiation
This is because that. Usually, the amount of Ar is more SiH _FourThan ten
It is set a lot more. The same applies to other film formations.
It Ions that irradiate the substrate surface directly contribute to film formation
It need not be an atom or molecule. Raw materials that contribute to film formation
The child, the molecule, and the ion irradiating the substrate surface are completely different.
In some cases, the amount of ion irradiation on the substrate and the deposition rate are independent
It can be controlled and is suitable for high quality film formation.

On the other hand, the resist stripping is usually performed by a wet process using a mixed solution (H ₂ SO ₄ + H ₂ O ₂ ) as described above, but the resist after the ion implantation step is mixed solution (H ₂ SO 4). _It does not dissolve in ₄ + H ₂ O ₂ ). for that reason,
It is removed by a strong oxidation reaction in oxygen (O ₂ ) plasma.

However, in the conventional apparatus, there is a problem of damage due to high-energy ion irradiation and metal contamination of the substrate surface due to sputtering of the chamber inner surface, and resist stripping has been made famous.

However, the device of the present invention (first, 7, 9, 1
0, 12, 14, and 15) can be applied to completely control the oxygen plasma, and resist stripping without damage or metal contamination is realized. If a small amount of Cl ₂ is added to O ₂ , the metal component contained in the resist is also removed. At the time of stripping the resist, the Si surface is thinly oxidized by O ₂ plasma, and the thin oxide film can be easily removed by vapor phase etching in which HF gas of about 0.6% is mixed in N ₂ and Ar. The Si surface from which the oxide film has been removed is terminated by fluorine.
It is easily removed by (Ar + H ₂ ) plasma accelerated to about 2 to 10 eV.

Next, regarding the dry cleaning, organic contaminants are cleaned with O ₂ ions or O ₃ accelerated to about 1 to 15 eV. As described above, the thin oxide film (SiO ₂ ) formed on the surface of bare silicon is 0.5 in N ₂ and Ar.
It can be removed with about 0.6% HF gas. The metal component is
It can be removed by Cl ₂ ions accelerated to 1 to 15 eV. The device of the present invention is sufficiently applicable.

[0113]

According to the present invention, a plasma processing apparatus configured to generate plasma in a depressurizable container and to process an object to be processed in the plasma,
The first and second electrodes are formed in a flat plate shape so as to face each other in the container, and are provided so as to cover at least the first electrode, which is made of a material stable to the plasma. A protective member, a holding means for mounting an object to be processed on the second electrode, a first high frequency power source connected to the first electrode, and a second high frequency power source connected to the second electrode. At least a high frequency power supply and a gas supply means for introducing a desired gas into the container are provided, and the frequency of the first high frequency power supply is set to be higher than the frequency of the second high frequency power supply. Various plasma processes such as RIE, plasma-enhanced chemical vapor deposition, resist asher, dry cleaning, etc., without causing damage or contamination to the substrate of the object to be processed and causing pollution of the processing atmosphere. Kotona Can be carried out, it is possible to provide a semiconductor device of high quality.

Further, the basic structural parts are not changed, and various plasmas can be obtained by changing specific specifications such as the output frequency of the high frequency power source and the type of gas to be introduced. Since it can be applied to process equipment, it is possible to standardize each equipment and realize consistent and uniform operation of semiconductor device manufacturing.

Further, since each device has a common constituent part, the manufacture, management, maintenance, etc. of the constituent parts can be facilitated and the performance of the entire device can be improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an apparatus showing a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing an example of the band eliminator of FIG.

3 is a graph showing resonance characteristics of the band eliminator of FIG.

FIG. 4 is a circuit diagram showing another example of the band eliminator shown in FIG.

FIG. 5: First and second for high frequency power to the second electrode
5 is a graph showing changes in the potential of the electrode of FIG.

FIG. 6 is a schematic configuration diagram showing an apparatus for measuring current-voltage characteristics of electrodes.

FIG. 7 is a graph showing an experimental example of current and voltage characteristics of electrodes.

FIG. 8 is a graph showing changes in self-bias voltage with respect to changes in frequency.

FIG. 9 is a schematic configuration diagram showing a second embodiment.

FIG. 10 is a schematic configuration diagram showing a third embodiment.

FIG. 11 is a circuit diagram showing another example of the band eliminator.

FIG. 12 is a schematic diagram showing a schematic configuration of a conventional example.

13A is a parallel plate electrode structure, and FIG. 13B is a distribution diagram of a high frequency electric field and a DC magnetic field.

FIG. 14 is a cross-sectional view of essential parts showing a fourth embodiment of the present invention.

FIG. 15 (a) is a circuit diagram showing an example of a short circuit,
(B) is a circuit diagram showing another example of the short circuit.

FIG. 16 is a sectional view showing a fifth embodiment of the present invention.

FIG. 17 is a sectional view showing a sixth embodiment of the present invention.

FIG. 18 is a magnetic field distribution (line of magnetic force) diagram.

FIG. 19 is a sectional view showing a seventh embodiment of the present invention.

FIG. 20 is a distribution diagram of magnetic force lines when the superconducting thin film is provided on the back surface of the electrode in the eighth embodiment.

FIG. 21 is a sectional view showing a ninth embodiment of the present invention.

FIG. 22 is a sectional view showing a tenth embodiment of the present invention.

[Explanation of symbols]

101 ... Protective layer (protective member), 102 ... Base material, 103 ... Substrate (processing target), 104 ... Susceptor electrode (second electrode), 105 ... vacuum container, 107 ... Electrode (first electrode), 110 ... a second high frequency power supply, 111 ... 1st high frequency power supply.

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 21/3065 C23C 16/505 C23F 4/00 H01L 21/205 H05H 1/46

Claims (22)

(57) [Claims] 1. A plasma is generated in a depressurizable container,
In a plasma processing apparatus configured to process an object to be processed in the plasma, first and second plate-like members provided in the container so as to face each other.
Electrode, holding means for mounting an object to be processed on the second electrode, a first high frequency power source connected to the first electrode, and a second high frequency power source connected to the second electrode. A plasma process apparatus comprising at least a high frequency power source and a gas supply means for introducing a desired gas into the container, wherein the first high frequency power source is a first through a coaxial connector.
Is connected to the first electrode by an inner conductor of
It is connected to the container by a hollow cone-shaped first outer conductor via a coaxial connector, and the first inner conductor and the first outer conductor have a second high frequency wave.
A plasma device connected by a first short circuit that short-circuits a high frequency from a power source . 2. The second high-frequency power source is connected to the second electrode by a second inner conductor via a coaxial connector, and is connected to the second outer electrode having a hollow conical shape via the coaxial connector. Connected to the container by a conductor, wherein the second inner conductor and the second outer conductor have a first high frequency
The plasma device according to claim 1, wherein the plasma device is connected by a second short circuit that short-circuits a high frequency from a power source . 3. The plasma according to claim 1, wherein the first short circuit is composed of a disc-shaped body made of an insulating material having a hole for inserting an inner conductor in a central portion thereof. apparatus. 4. The second short circuit is composed of a disk-shaped body made of an insulating material having a hole for inserting an inner conductor in a central portion thereof. Plasma device. 5. The plasma device according to claim 1, wherein an insulator is interposed between the first electrode and the container. 6. The plasma device according to claim 1, wherein an insulator is interposed between the second electrode and the container. 7. The plasma device according to claim 1, wherein an electromagnet or a permanent magnet is provided on the back surface of the first high-frequency electrode. 8. The plasma device according to claim 1, wherein an electromagnet or a permanent magnet is provided on the back surface of the second high frequency electrode. 9. The first inner conductor has a cylindrical end, and the electromagnet or permanent magnet is surrounded by the first inner conductor and the back surface of the first high-frequency electrode. The plasma device according to claim 7 or 8. 10. The second inner conductor has a cylindrical end, and the electromagnet or permanent magnet is surrounded by the second inner conductor and the back surface of the second high-frequency electrode. The plasma device according to claim 8 or 9. 11. The other short-circuiting circuit for short- circuiting the high frequency from the second high-frequency power source directly between the first electrode and the container is provided. The plasma device according to item 1. 12. The other short-circuit circuit for short- circuiting the high frequency from the first high-frequency power source directly between the second electrode and the container is provided. The plasma device according to item 1. 13. The superconductor or superconducting thin film exhibiting complete diamagnetism is provided on the back surface of the first and / or the second electrode, according to any one of claims 8 to 11. Plasma device. 14. The method of claim 13, wherein the first and / or second electrode superconductor plasma device of any one of claims 8 to 1 1, characterized in that coated with showing complete diamagnetism a. 15. The frequency of the first high frequency power supply is higher than the frequency of the second high frequency power supply, and the second frequency is 10 MHz or more.
4. The plasma device according to claim 4. 16. The second frequency is 10 MHz to 10 MHz.
16. The plasma processing apparatus according to claim 1, wherein the frequency is 0 MHz. 17. The second frequency is 10 MHz to 50 MHz.
17. The plasma processing apparatus according to claim 1, wherein the plasma processing apparatus has a frequency of MHz. 18. The method according to claim 1, wherein the first frequency is 100 MHz or higher.
The apparatus for plasma processing according to the item. 19. The plasma processing apparatus according to claim 1, wherein the plasma processing apparatus is any one of a reactive etching apparatus, a plasma chemical vapor deposition apparatus, and a resist asher. . 20. A protective member is provided which is made of a material that is stable to at least the plasma and is provided so as to cover the first electrode.
The plasma process apparatus according to claim 1. 21. The apparatus for plasma processing according to claim 1, further comprising magnetic field generating means for generating a magnetic field on the back surface of the first electrode. 22. The method according to claim 1, wherein the second frequency can be switched during processing of the object to be processed.
2. The plasma processing method according to any one of 1.