JPH10125665A - Plasma processing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform etching or deposition without causing damages or contamination on a substrate by setting the frequency of a high-frequency power supply to be connected with an electrode covered with a protective member stable with respect to plasma higher than the frequency of a high-frequency power supply to be connected with an electrode fixed with an object to be processed. SOLUTION: An upper electrode 107 and a lower susceptor electrode 104 are arranged oppositely in a vacuum container 105. The electrode 107 is formed by providing a protective layer 101 on a conductive base material 102. The protective layer 101 comprises SiO2 , Si3 N4 , etc., and protects the basic material 102 from being etched by a plasma generated through a discharge. The susceptor electrode 104 is connected with a power supply 110 feeding a high-frequency power of second frequency f2 through a matching circuit 108, and the electrode 107 is connected with a power supply 111 feeding a high frequency power of first frequency f1 which is higher than the frequency f2 .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to various plasma processes such as reactive ion etching (RIE),
The present invention relates to an apparatus used for performing a 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 vessel, 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 an integrated circuit (conductive thin films such as Al, W, and Ta, semiconductor thin films such as poly-Si and Si, and insulating thin films such as SiO ₂ , Si ₃ N ₄ , and Al ₂ O ₃ ) are used. RIE (Reactiv) with anisotropic etching
e Ion Etching) method, other Al (CH ₃ ) ₃ , AlH (C
H ₃ ) ₂ or the like as a raw material gas,
PCVD which decomposes into (CH ₃ ) ₂ and Al (CH ₃ ), adsorbs them on the substrate, and deposits Al by surface reaction
Film formation and the like.

[0003] The RIE method is a method of generating excited active species in a vacuum vessel, for example, CF ₄ F ₂ , CCl ₄ , C
A gas such as l ₂ , CF ₂ Cl ₂ (hereinafter referred to as an excited active species source gas) is introduced, a direct current or a high frequency power is applied to a susceptor as a means for holding the substrate, and a plasma is generated by causing a glow discharge. This is a method in which ions generated in the plasma and excited active species simultaneously act on the surface to be etched, thereby performing physical and chemical etching. According to this method, the selectivity to the photoresist, which is a mask material, is kept large. While anisotropic etching can be realized.

[0004] Even in a glow discharge with a high-frequency input, the substrate surface is DC-biased negatively with respect to the plasma (this is called self-bias), but the ions accelerated by the potential difference between this self-bias voltage and the plasma potential. Collides with the substrate surface and etches the substrate surface by the action of the excited active species adsorbed on the substrate surface.

FIG. 12 is a schematic diagram showing a cross-sectional structure of a typical reactive ion etching apparatus conventionally used. Reference numeral 503 denotes 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 denotes a susceptor electrode. High frequency power is supplied to the susceptor electrode 504 via a matching circuit, and the vacuum vessel (chamber) 505 is usually grounded for safety. Here, a high frequency power supply (RF power supply) whose output frequency is 13.56 MHz is generally used. In many cases, a plate-shaped electrode is provided so as to face above the susceptor electrode 504.

In an actual apparatus, in addition to the above configuration, an exhaust unit for evacuating and exhausting gas in the vacuum vessel 505, an inlet for introducing gas into the vacuum vessel 505, a mechanism for taking in and out the substrate 503, and the like are provided. Although they are provided, they are omitted in the figure to simplify the description.

[0007] The surface of the substrate 503 such as a semiconductor wafer and the surface of the susceptor electrode 504 are subjected to DC negative self-bias on the plasma due to the RF power applied to the susceptor electrode 504. The surface of the substrate to be etched is etched by acting on the surface of the substrate to promote a surface reaction.

[0008]

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

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

When the irradiation ion energy is increased, the resist is also etched, resulting in a change in the pattern size. As a result, it becomes impossible to perform fine processing accurately. In particular, such a phenomenon will be prominent in future highly integrated devices in which the thickness of the resist is about 0.5 μm or less.

Irradiation with ions having high energy causes damage (damage) to the underlying material, which leads to a reduction in the performance and reliability of an element made of such a material. In particular, serious troubles such as an increase in leak current and deterioration in breakdown voltage are caused.

Since the plasma potential is usually about +50 to 100 V, ions determined by the plasma potential collide with the inner surface of the chamber. Due to the ion bombardment of high energy, the inner surface of the chamber is sputtered, and the material constituting the chamber, For example, Fe, Ni, Cr, Cu, etc., contaminate the substrate surface. That is, the substrate surface contamination of the chamber constituent material due to the high energy ion collision. When the substrate surface is contaminated with such heavy metals, defects are generated on the substrate surface in the next high-temperature step or the leakage current is increased, so that the characteristics of the device are significantly deteriorated.

In the conventional apparatus, the frequency of the high frequency power supply is 13.56 MHz.
When the plasma excitation frequency is low, such as 3.56 MHz, the DC self-bias generated at the electrode becomes negative and large even when the gas pressure in the chamber and the high-frequency power are constant. FIG.
Means that the distance between opposing electrodes is 3 cm and the diameter of the disc electrode is 10 c.
The graph shows current-voltage characteristics when m, Ar gas pressure is 5 × 10 ⁻³ Torr, and high-frequency power is 50 W. In the figure, the horizontal axis represents the DC negative voltage applied to the electrodes, and the vertical axis represents the current flowing through the electrodes. A negative value of the current means that electrons flow into the electrode, and a positive value of the current means that positive ions flow into the electrode. The negative voltage when the current is 0 corresponds to the self-bias of the electrode. This is because high-frequency power is usually supplied to the electrodes via a capacitor, and no DC current flows.

As can be understood from FIG. 7, the self-bias of the electrode is as follows.
At 8MHz and 100MHz, -400V,
-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 gradually decreases as the frequency increases.

FIG. 8 shows the details. That is, the Ar gas pressure in the chamber is 7 × 10 ⁻³ Torr.
r, shows how the self-bias of the electrode changes when the high frequency of the high frequency power of plasma excitation is changed from 10 MHz to 210 MHz when the high frequency power is 100 W, the electrode interval is 3 cm, and the electrode diameter is 10 cm. As the frequency increases, the negative self-bias sharply decreases. FIG. 8 also shows the plasma potential, which has a frequency of 10 MHz.
Even if it changes from z to 210 MHz, it is almost kept at + 20V.

With the progress of ultra-miniaturization and ultra-high integration of LSI,
Aspect ratios of contact holes and via holes gradually increase. That is, it is required to etch a fine and deep hole with good controllability and good reproducibility.
Lower the gas pressure in the etching chamber (for example, 10 ⁻³ Torr).
It is necessary to lengthen the mean free path of the molecule by setting. Even in a state where the gas pressure is low, it is desirable that the frequency of discharge excitation be 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 high-order mode discharge occurs, and plasma with a uniform density is not excited in the electrode, so that 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 independently and directly controlled, and the pressure, flow rate, high-frequency power And the like must be indirectly controlled by appropriately combining such conditions.

In addition to the above-described RIE apparatus, the apparatus to be configured so as to be capable of processing the object at high speed without damaging the object other than the object in the plasma is
There are a PCVD apparatus, an O ₂ plasma resist asher, a dry cleaning apparatus, and the like. Conventionally, these apparatuses have been designed and manufactured individually, despite having common use conditions in a basic part. At the same time,
Had the disadvantages of

The above problems have been found by the present inventor, and the present inventors have conducted intensive research to solve the above problems that occur in the conventional apparatus, and have come to find a means for solving the problems.

According to the present invention, the substrate (substrate) can be etched or formed on the substrate without damaging or contaminating the surface, and the structure of the chamber and the electrodes is the same even though the structure is the same. By changing the gas to be introduced and the plasma excitation frequency, it can be applied to etching and film formation.
An object of the present invention is to provide a low-cost, high-performance plasma processing apparatus that is excellent in productivity.

[0021]

SUMMARY OF THE INVENTION The present invention provides a versatile apparatus applicable to various plasma processes while avoiding the above-mentioned damage and surface contamination and performing high-speed processing. In a plasma processing apparatus configured to generate plasma between two opposing electrodes installed in the plasma and to perform processing of an object to be processed in the plasma, the plasma processing apparatus is provided so as to oppose the inside of the container. A first and second electrode formed in a flat plate shape, a protection member made of a material stable at least to the plasma and provided to cover the first electrode; Holding means for attaching an object to be processed, a first high-frequency power supply connected to the first electrode, a second high-frequency power supply connected to the second electrode, and a desired gas in the container. For introducing Provided at a minimum and a scan supply means, wherein the first frequency of the high frequency power is set higher than the frequency of the second high frequency power supply.

[0022]

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

On the other hand, the energy of ions incident on the substrate surface 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 sufficiently reduced. 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 in the second electrode controls the ion energy applied to the substrate surface to an optimum value, the problems of damage and contamination are not involved.

When used in a PCVD apparatus, a substrate on which a deposited film to be processed is 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
H ₄ , SiH ₂ Cl ₂ , Si ₂ H ₆ and the like are introduced, and in the case of SiO ₂ film formation, a mixed gas of SiH ₄ and O ₂ or a mixture of Si ₂ H ₆ and O ₂ is introduced. Also in this case, it is possible to avoid damage to the substrate of the object to be processed and prevent contamination of the object to be processed, for the same reason as described for RIE.

Further, the prior art can be applied to a resist asher in which the problem of damage and contamination of the substrate surface is inevitable. For example, photoresist that is indispensable for fine pattern processing is usually stripped in a wet process using a mixture of H ₂ SO ₄ and H ₂ O _2. However, when used as a mask material for ion implantation, high-energy ion irradiation is performed. As a result, the resist is cured and cannot be peeled off in a normal wet process. Therefore, it was necessary to generate O ₃ and O radicals using O ₂ plasma, and remove the ion-implanted resist using ion energy.

When used for a resist asher, the above R
As mentioned in the description of IE and PCVD, if the substrate is placed 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 can be formed without damaging or contaminating the substrate surface. Can be peeled off.

As described above, although the condition setting is slightly changed at the time of use, the present invention can be widely applied to various plasma processing 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 a substrate surface. Here, a case where a thin film formed over a semiconductor substrate is etched will be described.

An upper plate electrode 107 and a lower plate susceptor electrode 104 are placed in a vacuum vessel (chamber) 105.
Are disposed so as to face each other, and the vacuum vessel 105
Is made of metal and connected to earth. Vacuum container 10
5 is coated with an oxide film, a nitride film or a fluoride film so as to be stable against plasma of a corrosive gas such as a fluorine-based or chlorine-based gas. I have. 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 protection member made of SiO ₂ , Si ₃ N ₄ , Al ₂ O ₃ , AlN, or the like. Have been.

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 , AlN and other materials. Further, it may be constituted by a passivation film made of fluoride satisfying a substantially stoichiometric ratio. This passivation film exhibits excellent etching resistance, and the passivation film may be formed, for example, as follows. That is, after 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 finished to a mirror surface without a work-affected layer by an electrolytic polishing technique or the like, high purity impurities are removed. Baking is performed at a predetermined temperature in an active atmosphere to remove adsorbed moisture. After baking, fluorination is performed at a predetermined temperature with high-purity fluorine, and heat treatment is performed at a temperature slightly higher than the temperature at the time of fluorination in a high-purity inert atmosphere after the fluorination treatment, thereby substantially satisfying the stoichiometric composition ratio. A passivation film is formed on the matrix.

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

The susceptor electrode 104 is connected via a matching circuit 108 to a high frequency power supply 110 for outputting high frequency power of the second frequency f ₂ . In this embodiment, 100 MH
An example of supplying high frequency power of z is shown. The potential control of the susceptor electrode 104, preferably, the second frequency f ₂ is suitably 10 to 50 MHz. Also, electrode 1
07, a susceptor electrode 104 via a matching circuit 109.
Outputs the first high-frequency power of the frequency f ₁ is a frequency higher than the frequency f ₂ to be supplied to the high frequency power source 11
1 is connected. In this embodiment, an example is shown in which high-frequency power of 250 MHz is applied. As will be described later in detail, it is desirable that the _two frequencies f ₁ and f ₂ do not have a relationship of an integral multiple.

Further, the electrode 107 and the susceptor electrode 1
04 has a first high frequency (250 MH in this example).
z) and a band eliminator (Band E) so that only the second high frequency (100 MHz in this example) is input.
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
2 is shorted to ground. The band eliminator 11 used for the electrodes 107 and 104
Basically, the components 2 and 113 may be configured, for example, 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 (in this case, f ₁ = 250 MHz) can be selected and supplied to the electrode.

The structure shown in FIG. 2 shown here merely shows the basic principle, and it goes without saying that various modifications may be made. For example, FIG. 4 is an example of an improvement.

[0036] The circuit 102b inductance Although the L ₁ via the direct current at the ground, a capacitor C as this if you want a DC floating state (floating), for example in FIG. 4 102d _It is sufficient to add _s and cut the DC component. In this case, the value of C _s so that the resonance frequency does not deviate from the frequency f ₁ of the circuit 102d is required to be sufficiently large value so as to satisfy the _{f 1 · L 1 »1 / f} 1 C s.

In this case, f ₀ = ｛1 / 2π (L
_For a frequency of ₁ C _s ) ^1/2 , the series circuit of L ₁ and C _s has zero impedance and is short-circuited to a high frequency of f ₀ . If this frequency f ₀ is made 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 superimposed on the electrode 107. That is, the electric field of the high-frequency power into the susceptor electrode 104, be perpendicular to terminate the electrode 107 from the susceptor electrode 104, because electrode 107 is short-circuited to ground for high frequency of f _2, electrode 107
It is not the voltage of fluctuates power frequency f _2.

Although the band eliminator 112 has been described above, if the band eliminator 113 has the same configuration, 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 .

It is assumed that f ₁ = 1 / 2π (L ₂ C _S2 ) ^1/2 .

In order to generate ions for forming plasma, the discharge of the excited active species source gas introduced into the vacuum vessel 105 is performed at a high frequency of frequency f ₁ . To thicken the ion density, increasing the power of the frequency f _1, it does not affect the voltage of the susceptor electrode 104.

The same can be said for the high frequency power of the frequency f ₂ supplied to the susceptor electrode 104. Be varied frequency power of a frequency f _2, the power of the f ₂ are electrodes 10
This is because at 7 is short-circuited to ground.

One example is shown in FIG. 5, where the distance between the first electrode and the second electrode is 3 cm, the diameter is 10 cm, and the gas pressure is 7 × 10 ⁻³ Torr. ,
When f ₁ = 100 MHz, the input power is kept constant at 150 W, and f ₂ = 30, 40, 50 MHz, the DC self-bias of the first electrode and the second electrode when the power is changed is plotted. ing. The self-bias of the first electrode is independent of the frequency and power supplied to the second electrode at about -25V. Potential of the second electrode, when there is no RF input is approximately 10V, as the high frequency power having a frequency f ₂ increases linearly decreases, a negative voltage at a certain power or more. As the frequency f ₂ is low, the change in the self-bias voltage for the same power change is large. In any case, it is clear from FIG. 5 that the DC potential (self-bias) of the electrode can be controlled by the high frequency power and its frequency without affecting the potential of the opposing electrode at all.

With the above configuration, it is possible to effectively prevent the high frequency supplied to the other from being superimposed on the electrode 107 and the susceptor electrode 104, and to supply only the high frequency to be supplied to each of them. Therefore, it is possible to easily and accurately control the self-biased plasma density and the ion energy to be irradiated.

It should be noted that a substantially parallel magnetic field is generated on the surface of the electrode 107 by the cylindrical magnet 106 provided on the back surface of the electrode 107, and the electrons follow the magnetic field and perform cyclotron motion. When a vertical high-frequency electric field exists between the electrodes 107 and 104, energy is effectively applied to the electrons moving in the cyclotron, and the high-frequency power effectively generates high-density plasma. Therefore, in this device,
The two input high-frequency electric fields are set so as to terminate almost vertically and at the susceptor electrode 104 and the electrode 107, respectively.

Reference numeral 106 denotes a permanent magnet for magnetron discharge. Actually, an electromagnet using a ferromagnetic material is preferable. Further, the apparatus is provided with an exhaust unit for evacuating the vacuum vessel 105, a mechanism for introducing gas, and a mechanism for taking the substrate 103 in and out, but these are omitted for simplification of description.

In the apparatus of the present embodiment, unlike the conventional apparatus, an electrode 107 is provided in addition to the susceptor electrode 104. Therefore, a high-density plasma is supplied to the electrode 107 by supplying a high-frequency power having a large power. Can be generated, and thus high-speed etching can be performed. However, when a high frequency power with 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
₁ is made 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 a protective layer 101 is provided on the surface of the base material 102 of the electrode 107.

On the other hand, as shown in FIG. 5, the self-bias generated at the susceptor electrode 104
Can be controlled by the power and frequency of
Considering the material of the thin film to be etched, the
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
In addition to generating high-density plasma by the high-frequency power supplied to the power supply 07 (the plasma density, that is, the ion density is controlled by the power), the frequency f ₂ for supplying the ion energy applied to the substrate surface to the susceptor electrode 104 is obtained. Since it can be controlled to a desired value by high-frequency power, high-speed RIE can be performed while preventing damage to the substrate 103 and the like.
Can be performed.

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

FIG. 6 shows an electrode 10 using the apparatus shown in FIG.
4 shows a circuit configuration for measuring current and voltage characteristics. High frequency filter 203 connected to the electrode 104
Is, for example, the band eliminator 102b shown in FIG.
, The impedance is high only at the frequency f ₂ of the high frequency supplied to the susceptor electrode 104, and almost short-circuited at a frequency shifted from that frequency. Is connected to a DC power supply 201 and an ammeter 202 in series. A capacitor 206 is connected in parallel to a 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 this state, for example, Ar gas is introduced into the vacuum vessel 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 current flowing when discharge is caused by the high-frequency power. In this case, the frequency of the high frequency power supply 110 is variable, for example, 14 MHz, 40.68 MHz and 1 MHz.
It is changed to three frequencies of 00 MHz. Note that the current into which the positively charged ions flow into the electrode 104 is a positive value.

For example, when looking at the characteristics at 100 MHz, when the DC voltage V is about -95 V (this value is referred to as a self-bias voltage V _SB ), the DC current I = 0, and V> V _SB
In this case, I <0 and I> 0 when V < _VSB . The self-bias voltage V _SB is a DC bias voltage generated when the electrode 104 is discharged at a high frequency in a floating state. That is, when the electrode 104 is at this potential, the numbers of ions and electrons flowing from the plasma into the electrode 104 become equal, and thus cancel each other, and the DC current becomes 0.
Becomes

On the other hand, when the potential of the electrode 104 is controlled by a 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 satisfied, more electrons flow and I <0.

On the other hand, in the case of the relation of V < _VSB , the potential barrier for electrons is increased and the number of inflows of electrons is reduced, so that the ionic current becomes larger and a positive current flows. Further, when the DC voltage V is increased in the negative direction, 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 = V _SB
The slope of the -V characteristic curve corresponds to the width of the electron energy distribution. In other words, a large inclination means that the width of the electron energy distribution is narrow. As is clear from FIG. 7, the energy distribution at 100 MHz is smaller than that at 14 MHz by about 1/10.
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. It can be said that it has decreased to 10.

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

In the conventional RIE method, the underlying substrate is damaged and the characteristics of the device are degraded. This is due to the following reasons.

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

However, in the first embodiment of the present invention, since the electrode 107 is discharged using a high frequency of 250 MHz, the electric current is ΔΔ compared to the conventional case of 13.56 MHz.
E _ion can be reduced to 1/20 or less. In the device of the present invention, the discharge is applied to the frequency f ₁ applied to the electrode 107.
, Which generates high-density plasma, and supplies a higher frequency f ₁ (2) than the frequency f ₂ supplied to the susceptor electrode 104.
(50 MHz), the distribution width of the ion energy in the generated high-density plasma is also 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 when a high-frequency power of 50 W is input, and The density is improved by about 10 times or more. According to FIG. 5, the high-frequency power is 100 W, the self-bias is about −10 V at f ₁ = 210 MHz, so that f ₁ = 250 MHz
, The self-bias is -5V or less.

The self-bias of the electrode 107 is as low as −5 V or less, and since the protective layer 101 is provided, the base material 102 of the electrode 107 is not sputtered at all. Therefore,
The high-frequency power to the frequency f ₂ is applied to the susceptor electrode 104, the self-bias is controlled small enough not to damage the substrate becomes very easy, and a desired power frequency f ₁ so that the etching rate is obtained Is set so that ions having a large energy that may damage the substrate surface are not irradiated, and high-speed and highly selective etching is performed without causing damage to the thin film, the resist film or the underlying substrate. It becomes possible.

That is, the self-bias voltage V _SB decreases as the frequency of the high-frequency power supply increases and as the high-frequency power decreases. Therefore, it is only necessary to select a frequency and an electric power to be supplied to the susceptor electrode 104 so that the quality of the thin film or the base substrate is not damaged and the ion energy and the ion irradiation amount required for the high-speed etching are obtained.

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 the base material 102 can be prevented from being etched because the protective layer 101 is formed. Further, in the embodiment of FIG. 1, the permanent magnet 106 is mounted, and this allows the magnetron discharge (electrons wrap around the magnetic field lines and perform cyclotron motion to receive energy from the high-frequency electric field to generate neutral excitation. (The active species source gas molecules are efficiently ionized), and the ion concentration is increased, so that the etching rate can be further increased.

As described above, according to the dual-frequency excitation RIE apparatus of the present invention, it is possible to etch a high-quality thin film or substrate without damaging the substrate at a high selectivity while maintaining a high etching rate. Was.

Further, as shown in FIG.
The energy of ions flowing into the susceptor electrode 104 can be controlled by applying a DC bias voltage to the susceptor electrode 104. The method of controlling the potential of the susceptor electrode 104 by applying such a DC bias voltage, 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 the high-frequency power supplied to the
Although only the case where the frequency is set to 50 MHz has been described, it goes without saying that the selection of the frequency is not limited to this.

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

The magnet 1 installed on the back surface of the electrode 107
Reference numeral 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 this embodiment, a strong racetrack magnet 409 is provided, and scanning is performed to improve the uniformity of the magnetic field. In this case, the scanning system 410 of the magnet 409 is connected to the vacuum vessel 1
If the reaction system is provided outside, the reaction system can be advantageously prevented from being contaminated by dust generated from mechanical operation.

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

In order to further reduce damage to the substrate 103, for example, the following method can be employed. For example, when etching an insulating film such as SiO ₂ formed on the surface of a substrate 103 such as Si, first, several μm
While a film having a thickness of about m is formed, the RF power supplied to the susceptor electrode 104 is increased to perform high-speed etching, and the RF power is switched to a small value just before the surface of the substrate 103 starts to be exposed. In this way, since the etching can be performed with a sufficiently low self-bias state after the substrate 103 starts to be exposed, damage to the substrate surface can be reduced to almost zero.

If the kinetic energy of the ions applied to the surface of the substrate 103 is too large, any material may be damaged. Damage to a material begins when the kinetic energy of the irradiated ions is slightly greater than the critical energy for damage determined by the interatomic bonding force of each material. Generally, an insulator has a larger atomic bonding force than 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, in which the substrate 1
3 shows a method in which damage to the substrate 103 is eliminated and the energy of ions to be irradiated on 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. 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 A band eliminator 401 in which two resonance circuits 402 and 403 are connected in series is Since the impedance is increased only at two frequencies f ₂ and f ₃ and is substantially short-circuited at other frequencies, these two
Susceptor electrode 104 selectively for only one type of high frequency
Has the function of supplying power to

For example, f ₁ = 250 MHz and f ₂ = 1
00 MHz and f ₃ = 40 MHz. For example, while the first film having a thickness of about 0.5 to 1 μm is formed, the frequency of the high frequency applied to the susceptor electrode 104 is changed to f.
_{When the} frequency is ₃ (40 MHz), the self-bias becomes as large as 0 to -100 V as shown in FIG. 5, and a large etching effect is obtained. When the surface becomes approximately 100 °, the frequency is switched to f ₃ (100 MHz) and a thin film (for example, 10 ° to 100 °) is etched. In this way, when the substrate surface starts to be exposed, the substrate surface is irradiated with ions with a small self-bias value (about -10 to -20 V) corresponding to 100 MHz, and the substrate is hardly damaged.

Such a method is particularly important when controlling the flatness of the surface shape of the thin film deposited by the RIE method. This is because the most effective energy of 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.

[0075] Here, although described only for the case of two different Ru frequency of f _2, f _3, for example f _2, f _3, may of course be used three values of f _4. However, in this case, the first applied frequency f ₄ is f ₄ > f ₂ ,
As f _3, it is important to reduce the damage using the highest frequency that enough made later.

[0076] In the case of using a plurality of frequencies, these frequencies f _1, including for discharge excitation, f _1, f _2, f _3, · ·
It is desirable to select the values so that they do not have a harmonic relationship with each other. The discharge space is non-linear and therefore f ₁ , f ₂ , f ₃ ,
.. May be superimposed in completely different states depending on the discharge conditions, and the setting of the conditions is not unique.

The resonance circuits 402 and 4 shown in FIG.
A similar effect can be obtained by using the resonance circuit shown in FIG. However, in FIG. 11, it is necessary to satisfy C _S ≫C ₂ , C ₃ .

Next, the concept of high performance common to various processes, in which plasma is generated between opposed parallel plate electrodes, which is a basic component of the RIE apparatus, will be described.

The prerequisites for improving the performance of the discharge plasma process are (1) no damage to the substrate surface, and (2) no contamination on the substrate surface by sputtering of a vacuum vessel or electrode material. Requirements. Needless to say, there is a need for specific high-performance etching and film formation such as high-speed etching and high-speed film formation, realization of high-density plasma with as little RF power as possible. Nor.

In order to fulfill the requirements (1) and (2), the plasma potential of the plasma formed by the discharge is:
It is required that the value be such that the vacuum vessel and the electrode material are not sputtered, that is, +30 V or less, preferably +20 V or less. The vacuum vessel is normally used in a state of being grounded, but the energy of the ions incident on the inner surface of the vacuum vessel is about the plasma potential. Electrode 102
Normally, a negative voltage is applied to the susceptor electrode 104 by supply of high-frequency power, so that ions having a positive charge are incident on the susceptor electrode 104, and the energy is controlled to an energy value having a required purpose. In any case, it is an essential condition that the plasma potential formed between the opposing electrodes is suppressed to a range of about +5 to +20 V. The energy of each ion irradiating the substrate surface has an optimum value for the substrate surface material according to the purpose of etching and film formation. It is adjusted to the optimum value of each material the individual ion energy, by adjusting the high frequency power of a frequency f ₂ which is supplied to the susceptor electrode 104, the susceptor electrode 104 self-bias voltage -V
_s (V) may be set so that V _OP = V _P + V _S. This is because if ions do not collide between the plasma and the substrate surface, the ion energy of the substrate surface irradiation is determined by the potential difference between the plasma potential and 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 opposed electrodes is kept at a low positive voltage. That is, V _P <V _OP must be satisfied. 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
As _P is satisfied, the plasma potential V _P at a low positive voltage
Is set. Here, V _SP is a sputtering start voltage of the vacuum vessel and the electrode material.

As described above, the improvement in the performance of the plasma application apparatus requires that the plasma potential be reduced to a low positive voltage (V _SP > V _P , V
_OP > V _P ). The reason that the plasma potential increases with a positive voltage is mainly that electrons with a negative charge, whose mass is lighter than ions, escape from the plasma space, ions with a positive charge become excessive, and the plasma generates a positive charge. Depends on having. In other words, in order to keep the plasma potential at a low positive 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 to occur as effectively as possible.

Next, a DC magnetic field distribution and a high-frequency electric field distribution which 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 opposing flat electrode 107 and susceptor electrode 104,
A high frequency electric field distribution (solid line) 602 is shown. FIG. 13A shows an example of the ideal state. In other words, a DC magnetic field exists parallel to the pole plates of both electrodes 107 and 104 facing each other, and a high-frequency electric field exists vertically between the pole plates. Electrons existing between the plates make a circular motion (cyclotron motion) around a DC magnetic field. Since a high-frequency electric field exists in the direction of movement of the circularly moving electrons, energy is efficiently converted from the electric field to the movement of the electrons. The electrons that have gained energy are confined by performing cyclotron motion between the electrode plates, and thus efficiently collide with neutral molecules and atoms to ionize the molecules and atoms. The electrode 107 and the susceptor electrode 104 receive a high-frequency input, and the self-bias is usually a negative voltage. Therefore, electrons having negative charges do not enter both electrodes. Therefore, electrons are confined between both electrodes in the vertical direction. However, since the ends of the two electrodes in the parallel direction are merely 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 intensity of the DC magnetic field B is 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 at the portion where the magnetic field intensity is increased, and are confined in the portion with the constant magnetic field intensity.

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 denoted by the same reference numerals, and duplicate description will be omitted.

Frequency f for exciting discharge between electrodes
_One high frequency power is supplied through a coaxial connector 710. Reference numeral 716 denotes an inner conductor that guides high-frequency power to the electrode 102, and 712 denotes an outer conductor of a tapered coaxial cable, which is connected to the metal vacuum vessel 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 of FIG. 14, it is formed by the electromagnet. Reference numeral 715 is a magnetic material having a high magnetic permeability μ and a high saturation magnetic flux density constituting the electromagnet, and 714 is an electric wire for supplying a direct current. Electromagnet, the inner conductor 716 and because it is completely surrounded by the base material 102 of the electrode, is not exposed to an electric field and a magnetic field of high frequency of f _1.

High frequency power having a frequency f ₂ for controlling the self-bias of the susceptor electrode 104 is supplied through a coaxial connector 711. 717 is the inner conductor of the coaxial cable, 7
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 high frequencies of frequencies f ₁ and f ₂ , respectively.

Reference numerals 708 and 709 denote insulating substrates constituting these short circuits, for example, made of Teflon-impregnated insulating material. A circuit for short-circuiting the inner conductors 716 and 717 and the outer conductors 712 and 713 is formed in a conical shape so as to conform to a cylindrical coaxial configuration. FIGS. 15A and 15B show examples of the short circuit. The short circuits 1, 2
Hole 80 for inserting inner conductors 716 and 717 in the center
5,806 is provided, and the substrate is formed in a disk shape using a Teflon-impregnated insulator. In the example shown in FIG. 15, an example is shown in which four series resonance circuits are radially arranged at an angular interval of 90 degrees from each other. Reference numerals 801 and 803 denote inductances, and reference numerals 802 and 804 denote high-frequency capacitors such as multilayer ceramics. The shaded area indicates the C remaining on the insulating substrate.
u thin film. The thin film usually has a thickness of about 35 to 70 μm. The thickness of the insulator substrate is about 1 to 3 mm, depending on the high frequency power. In FIG. 15A, an inductance having a straight line is used as the inductance 801 and the capacitor is a chip capacitor. In FIG. 15B, a coil formed by winding an electric wire by a required number of turns is used as the inductance 803.
4 uses a flat plate capacitor.

The description returns to FIG. Since the high-frequency power, particularly the power of the frequency f ₁ that forms a discharge between the electrodes, is efficiently confined between the electrodes, the electrode 102 and the susceptor electrode 104 are formed by insulating ceramics 706 and 707.
Each is configured to be floating from the vacuum container 105.
The distance from the electrode to the vacuum vessel is farther than the electrode interval. This is because the electric field of the high-frequency power having the frequency f ₁ incident on the electrode 102 is almost terminated to the susceptor electrode 104. After terminating at the susceptor electrode 104, the high-frequency current having the frequency f ₁ flows out to the outer conductor 712 via the inner conductor 717, the short circuit (L ₁ , C ₁ ), and the vacuum vessel 105.

The electrode spacing depends on the gas pressure, but is usually 2 to
It is about 10 cm. Since the electrode area is set larger than the substrate 103, if the diameter of the wafer as the substrate 103 is 6 inches, 8 inches, and 10 inches, at least the diameter of the electrodes is 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.

Frequency f supplied to 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 provided directly between the susceptor electrode 104 and the vacuum vessel 105. The point of the configuration of this embodiment is that a magnetic field as strong as possible is provided between two opposing electrodes.

In the case of an electromagnet composed of the coil 722 and the magnetic body 715 as in the embodiment shown in FIGS. 16 and 17, the distribution of the magnetic force lines has a distribution spreading downward as shown in FIG.

As in the seventh embodiment shown in FIG. 19, when 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 lines of magnetic force do not leak outside the superconductors 731 and 732, they exist only between the two electrodes.

When the substrate 103 needs to be cooled,
For example, an extremely large magnetic field confinement effect can be generated by coating the back surface of the electrode with an oxide superconductor exhibiting a superconductivity phenomenon at the temperature of liquid nitrogen by about 1 μm or more by sputtering. The eighth embodiment shown in FIG. 20 shows such a magnetic field confinement effect.

Similarly, in order to confine the magnetic field between both electrodes and generate a strong parallel magnetic field, electromagnets (721, 723) are provided not only on the electrode 102 side but also on the susceptor electrode 104 side. I just need. FIG. 21 shows a ninth embodiment constructed based on such a principle. Electromagnets (715, 722), (721, 723)
Are inner conductors 716 and 717 for supplying high frequency power.
Are substantially enclosed by Electric wires for supplying current to the coils 722 and 723 pass through the inner conductors 716 and 717 and are drawn out to the outside.

In the ninth embodiment, the electrodes 102, 1
It is more preferable to coat a completely diamagnetic superconductor on 04. In this embodiment, in the vacuum vessel in which discharge plasma is formed, the vessel main bodies 706 and 707 are made of ceramic, and the outer vessel 105 'is made of metal. The outer container 105 'plays the role of flowing the ground and the high-frequency current. With this configuration, the first, ninth, and first
The discharge between the electrode 102 and the vacuum vessel, which was observed in the apparatus of each embodiment shown in FIG.
Since the plasma is almost confined between the electrodes 104, 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 by permanent magnets. The material constituting the permanent magnet usually has a low relative magnetic permeability.
５5 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.
0 Donut-shaped complete diamagnetic superconductor 75 as in the embodiment
It is good to fit 1,752. In this case, the superconductor 75
The magnetic bodies 715 and 721 in which 1,752 are fitted are made of permanent magnets.

The RIE apparatus that completely suppresses sputter contamination of the chamber material and does not cause any damage to the substrate has been described. However, the gas introduced into the vacuum vessel differs depending on the material to be etched, Cl ₂ , Si
Cl ₄ , CH ₂ Cl ₂ , CCl ₄ etc.), fluorinated (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, He, additive gases H ₂ , and O ₂ are added.

It is required from the standpoint of uniform etching that the wavelength of the output frequency f ₁ of the high frequency power supply used for the high frequency discharge is at least larger than twice the diameter of the wafer. Preferably the frequency f ₁ is, 100 MHz (wavelength 3m) ~ 1 g
Hz (wavelength 30 cm).

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

Although the embodiments of the present invention have been described mainly with respect to etching of a SiO ₂ or Si film, it is needless to say that 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 l, W, Mo, Ta, Ti or alloys thereof.

The source gas of the excited active species may be appropriately selected according to the type of the 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
In the case of a Si thin film, Cl ₂ , CCl ₂ F ₂ , CF _4, etc., and in the case of a SiO ₂ thin film, CF ₄ / H ₂ , C ₂ F _6, etc.
In the case of 1 thin film, CCl ₄ , SiCl ₄ , BCl ₃ , Cl _{2 and the} like may be used, and in the case of Mo thin film, W thin film, Ti thin film, Ta thin film and the like, F ₂ , Cl ₂ , CF _{4 and the} like may be used appropriately. Also, H ₂ ,
It is also effective to add O ₂ and N ₂ as additive gases.

The substrate 103 on which these are formed is also
It 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 be applied to etching of a polymer material such as a polyimide film and a resist. Needless to say, the substrate on which the etching is performed 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 structure of each of the above embodiments is not limited to the above-mentioned RIE, but also includes PCVD, dry cleaning,
It can be easily used for resist ashing, dry development of the resist, etc. by partially changing the use conditions.

First, plasma CVD (PCVD) is performed. SiH ₄ , Si ₂ H ₆ , SiH ₂ Cl ₂
Or a raw material gas such as Ar, He, H _2, etc., to form an Al film by H ₂ + Al (CH ₃ ) ₃ ,
A gas such as H ₂ + AlH (CH ₃ ) ₂ is used for forming a SiO ₂ film.
A gas such as SiH ₄ + O ₂ , SiH ₂ Cl ₂ + O ₂ , and a gas such as SiH ₄ + NH ₃ + H ₂ are supplied for forming a Si ₃ N ₄ film. In the embodiment shown in 1,7,9,10,12,14,15 figure, these raw material gas into a plasma state is discharged by a high frequency power source f _1. Although high-density plasma is formed between the electrodes, because the high frequency f ₁ is kept as high as 150～250MHz, self-bias appearing on the electrode 102, the lower electrode and -10 to-2V is sputtered Absent. Furthermore, the substrate surface irradiated ion energy required for film formation, frequencies lower than f ₁ f ₂ (e.g., 10 to 80 m
(Hz). Irradiation ion energy is controlled by the power of f ₂ to the optimum value required for the deposition,
Irradiation ion density is controlled by the power of the f _1. For example, in the case of forming a Si film, if a gas for supplying (Ar + SiH ₄ ) is used, it is important to adjust the mixing ratio of Ar and SiH ₄ . In particular, in order to perform high-quality Si film formation at a low temperature from room temperature to about 400 ° C., it is necessary to use Si irradiation by ion irradiation.
This is because activation of the surface is decisive. For example, 1
This is because the number of irradiated ions having the optimum energy is usually required to be one or more while the number of Si atoms falls in the regular lattice position. This is because, for example, one Si atom is irradiated with 10 ions or 50 ions. Usually, the amount of Ar is set to be much higher than that of SiH ₄ . The same applies to other film formations. The ions that irradiate the substrate surface need not be atoms or molecules that directly contribute to film formation. The atoms and molecules that contribute to the film formation and the substrate surface irradiation ions are completely different, so that the amount of ion irradiation of the substrate and the film formation rate can be controlled independently, which is suitable for high quality film formation.

[0109] On the other hand, resist stripping is usually as described above, a mixed solution _{(H 2 SO 4 + H 2} O 2) is carried out by a wet process using a mixture resist after the ion implantation step (H ₂ SO 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 inner surface of the chamber.

However, the apparatus of the present invention (first, seventh, ninth, first)
0, 12, 14, and 15), the oxygen plasma can be completely controlled, and the resist stripping without damage and without metal contamination can be realized. If some Cl ₂ is added to O ₂ , the metal component contained in the resist is also removed at the same time. When the resist is stripped, the Si surface is thinly oxidized by O ₂ plasma, and the thin oxide film can be easily removed by gas phase etching in which about 0.6% of HF gas is mixed in N ₂ and Ar. The silicon 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, in the case of dry cleaning, organic contamination is cleaned by 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 the bare silicon has a thickness of 0.5% in N ₂ and Ar.
It can be removed with about 0.6% of 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, there is provided a plasma processing apparatus configured to generate plasma in a vessel capable of reducing pressure and to process an object to be processed in the plasma.
First and second electrodes, which are provided in the container so as to face each other and are formed in a flat plate shape, and are provided at least to be made of a material stable against the plasma and to cover the first electrode; A protection member, holding means for attaching an object to be processed on the second electrode, a first high-frequency power supply connected to the first electrode, and a second high-frequency power supply connected to the second electrode. A high-frequency power supply and at least gas supply means for introducing a desired gas into the container, wherein the frequency of the first high-frequency power supply is set higher than the frequency of the second high-frequency power supply. Various plasma processes such as RIE, plasma-enhanced chemical vapor deposition, resist asher, and dry cleaning do not damage or contaminate an object to be processed and cause contamination of a processing atmosphere. That Can be carried out, it is possible to provide a semiconductor device of high quality.

Also, without changing the basic structural components, various plasmas can be obtained only by changing specific settings such as the output frequency of the high-frequency power source, the type of gas to be introduced, and the like. Since the present invention can be applied to a process device, standardization of each device becomes possible, thereby realizing consistent and unified operation of semiconductor device manufacturing.

Further, since each device has a common component, manufacturing, management, maintenance, and the like of the component parts are facilitated, and the performance of the entire device can be improved.

[Brief description of the 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 illustrating an example of the band eliminator of FIG. 1;

FIG. 3 is a graph showing resonance characteristics of the band eliminator of FIG. 2;

FIG. 4 is a circuit diagram showing another example of the band eliminator of FIG. 2;

FIG. 5 shows first and second high-frequency powers to a second electrode.
6 is a graph showing a change in the potential of the electrode of FIG.

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

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

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

13 (a) shows a parallel plate electrode structure, and FIG. 13 (b) is a distribution diagram of a high-frequency electric field and a DC magnetic field.

FIG. 14 is a sectional view of a main part showing a fourth embodiment of the present invention.

FIG. 15A 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 (lines of magnetic force).

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

FIG. 20 is a view showing the distribution of lines of magnetic force when the superconducting thin film is provided on the back surface of the electrode according to 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]

 Reference Signs List 101: protective layer (protective member), 102: base material, 103: substrate (workpiece), 104: susceptor electrode (second electrode), 105: vacuum vessel, 107: electrode (first electrode), 110 ... a second high frequency power supply 111 ... a first high frequency power supply

Claims (1)

[Claims] 1. A plasma processing apparatus configured to generate plasma in a container capable of being depressurized and to process an object to be processed in the plasma. A first and a second electrode formed in a shape, a protection member made of a material stable at least to the plasma and provided to cover the first electrode, and a cover member on the second electrode. Holding means for attaching a processed object, a first high-frequency power supply connected to the first electrode, a second high-frequency power supply connected to the second electrode, and a desired gas in the container. An apparatus for plasma processing, comprising at least gas supply means for introducing gas, wherein the frequency of the first high-frequency power supply is higher than the frequency of the second high-frequency power supply.