JP2000183039A - Plasma processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a processing device to be lessened in size and scaled up in development contents, by a method wherein the space scale of electron's motion in a plasma generating region is enlarged A times, and a time scale is reduced to 1/B when a plasma processing device is similarly enlarged A times in scale, and the motion state of electron is controlled based on the product of a space scale multiplied by a time scale. SOLUTION: It is required that a gas pressure in a plasma generating region is set so as to be reduced to 1/A. This low pressure of gas is attained by controlling a space pressure with a vacuum pump connected to an exhaust means 18. When a law of similarity is applied, it is preferable that electrons in a plasma generating region are enhanced in incident energy. Therefore, an electron acceleration potential difference between a blocking/transmitting mechanism 13 and a plate electrode 10 is enlarged A times. In this case, the state of a motion r(t) of an electron is controlled so as to be a motion A.r(t/B) taking advantage of a position vector r( t) as a function of a time t. By this setup, a plasma processing device enlarged A times in scale is capable of having the same plasma state as a plasma processing device of original scale.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a plasma processing apparatus and method, such as a plasma etching apparatus and a plasma film forming apparatus.

[0002]

2. Description of the Related Art Conventionally, as an apparatus for performing plasma processing such as etching on an object to be processed such as a semiconductor wafer or an LCD substrate, a parallel plate plasma processing apparatus (diode parallel plate) has been used.
a plasma processing apparatus in which an electron formation region, a plasma generation region, and a plasma processing region are disposed adjacent to each other in one processing chamber as in a plasma enhanced system, and an ECR plasma processing device (ECR plasma
Various plasma processing apparatuses such as an apparatus in which a plasma generation chamber and a plasma processing chamber are separated from each other, such as an enhanced system, are known.

The present invention can be implemented in any type or mechanism of plasma processing apparatus. For convenience of explanation, a parallel plate type plasma etching apparatus will be described as an example.

FIG. 5 shows a parallel plate type plasma processing (etching) apparatus. Referring to FIG. 5, processing vessel 102 of parallel plate type etching apparatus 100 is made of a conductive material (eg, aluminum whose surface is anodized) and has a substantially cylindrical shape. The processing vessel 102 is provided with a mounting table 104 on which an object (eg, a semiconductor wafer) is mounted, and a processing chamber 106 for performing a plasma process on the object.

[0005] An insulating support plate 103 made of an insulating material (for example, ceramics) is provided at the bottom of the processing chamber 106, and a mounting table 104 for an object to be processed is provided above the insulating support plate 103. The mounting table 104 has a substantially columnar shape and is made of a conductive material (eg, anodized aluminum). On the mounting table 104, an electrostatic chuck 111 for suction-holding an object to be processed is provided. The mounting table 104 also has a function of a lower electrode, and
The high frequency power pulse train for bias is applied from 6 through the amplifier 130 and the matching circuit 132.

In the mounting table 104, the refrigerant circulating means 10
The workpiece W placed on the mounting table 104 is cooled, and the temperature of the surface to be processed is adjusted to a predetermined temperature. Heat transfer gas supply holes (not shown) are formed substantially concentrically in the electrostatic chuck 111. A heat transfer gas (eg, helium gas) is supplied to each heat transfer gas supply hole via a heat transfer gas supply pipe 113, and the heat transfer gas is formed between the workpiece W and the electrostatic chuck 111. And the heat transfer efficiency between the refrigerant circulating means 105 and the object to be processed W is increased.

The peripheral edge of the upper end of the mounting table 104 has a focus ring 115 which substantially conforms to the outer peripheral shape of the object to be processed, so as to surround the object W mounted on the electrostatic chuck 111. ing. The focus ring 115
It is made of an insulating material (eg, quartz) and has an action of not attracting reactive ions and the like in the plasma. The reactive ions and the like enter only the target object W inside the focus ring 115.

An exhaust ring 117 having a plurality of apertures is provided between the mounting table 104 and the inner wall of the processing vessel 102.
It is formed so as to surround the mounting table 104. The exhaust ring 117 has a function of adjusting the flow of the exhaust gas, and the processing gas and the like are uniformly exhausted from inside the processing container 102.

An exhaust pipe 108 is connected to the bottom side wall of the processing chamber 106. The other end of the exhaust pipe 108 is connected to evacuation means 110 via a valve or the like (not shown). The inside of the processing chamber 106 is maintained at a predetermined reduced pressure (eg, 1 to 100 mTorr) by the evacuation unit 110.

A substantially cylindrical upper electrode 112 is provided on an upper wall of the processing chamber 106 facing the mounting table 104 (also serving as a lower electrode). The upper electrode 112 is made of a conductive material (eg, aluminum whose surface is anodized). A gas supply pipe 114 is connected to the upper electrode 112. The gas supply pipe 114 is connected to a valve 116 and a mass flow controller (MFC) 118.
Is connected to the gas supply source 120.

The inside of the upper electrode 112 is
a, and the surface 112b facing the workpiece W is
It has many gas outlets 112c. Gas flood source 1
The processing gas (eg, C4F8 gas) from the discharge port 20 is introduced into the hollow portion 112a in the upper electrode 112.
From 12c, it is uniformly introduced into the processing chamber 106. The upper electrode 112 is electrically connected to a high frequency pulse power supply 128 via a matching circuit 125 and an amplifier 126. A high-frequency pulse train having a predetermined frequency and an output value from the high-frequency pulse power supply 128 is amplified by an amplifier 126, and the high-frequency power pulse train from the amplifier 126 is processed by a matching circuit 125 so as to match a resonance condition in the processing chamber 106. Applied to the electrode 112. Upper electrode 11 to which the high-frequency power pulse train is applied
A sensor 121 for detecting the state of the high-frequency power pulse train is provided near the feeding point 2 and the value detected by the sensor is fed back to the controller 129.

The controller 129 is connected to the high frequency power supply 128 and the amplifier 126 and controls each of them. With this control, a high-frequency power pulse train having a predetermined frequency and an output value is formed by the high-frequency power supply 128 and the amplifier 126, and is applied to the upper electrode 112.

The lower electrode 104 is connected to the matching circuit 13
2. It is electrically connected to the high-frequency pulse power supply 136 via the amplifier 130. A high frequency pulse train for bias having a predetermined frequency and an output value from the high frequency pulse power supply 136 is amplified by the amplifier 130, and the high frequency pulse train for bias from the amplifier 130 is applied to the upper electrode 112 via the matching circuit 12510 for resonance conditions. Is done. The controller 129 includes the amplifier 130 and the high-frequency power supply 13
6, and controls the amplifier 130 and the high-frequency power supply 136 to form a bias high-frequency power pulse train having a predetermined frequency and output value.

A sensor 133 for detecting the state of the high-frequency power pulse train is provided near a feeding point of the lower electrode 104 to which the bias high-frequency power pulse train is applied, and the bias applied to the lower electrode 104 by the sensor is provided. One of the maximum value, the minimum value, and the average value of the potential of the high-frequency power pulse train for use is measured, and the measured value is fed back to the controller 129. The controller 129 appropriately controls the formation of the high-frequency power pulse applied to the upper electrode 112 and the lower electrode 104 according to the returned measurement value.

[0015]

In the manufacture of a product (eg, a semiconductor device) using the above-described plasma processing apparatus, it is necessary to improve the performance of the product and to increase the manufacturing efficiency. There is a demand for a small processing system and a scale-up of the development content.

In order to realize a small system of the plasma processing apparatus and to scale up the contents of the development, it is necessary to optimize the state of the plasma in the apparatus. (Chemical and physical conditions such as material properties, shape, vacuum state, working frequency, working gas, ambient temperature, etc.), it is not easy to optimize the plasma according to the processing content. The present invention is a method corresponding to such a need, and applies a similarity rule of an electric element to be described later in order to optimize a state of plasma in a plasma processing apparatus.

Even when this similarity rule is applied, as described above, the state of the plasma depends on various factors of the generation space (material properties, shape, vacuum state, used frequency, used gas, ambient temperature, etc. Physical conditions),
It is difficult to simply apply the similarity rule of the electric element to the plasma processing apparatus.

It is an object of the present invention to overcome such difficulties and realize a small system of a plasma processing apparatus and scale-up of development contents.

It is another object of the present invention to form optimal accelerating electrons for plasma formation when the similarity rule is applied to a plasma processing apparatus.

[0020]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in a conventional plasma processing apparatus and a conventional plasma processing method.

An object of the present invention is to solve the above-mentioned problems by focusing on the behavior of electrons and controlling the behavior so that the similarity rule of electric elements can be applied to a plasma processing apparatus.

In accordance with one aspect of the present invention, electron formation and
An electron formation region having an acceleration mechanism, and a plasma generation region adjacent to the electron formation region and into which a processing gas for plasma formation is introduced, wherein the processing gas and electrons introduced from the electron formation region are A plasma generating region in which plasma is formed by the action of the plasma processing region, and a plasma processing region adjacent to the plasma generating region and provided with a mounting table for mounting a target object, wherein the target object is the plasma A plasma processing apparatus having a plasma processing area in which predetermined processing is performed by plasma introduced from a generation area, wherein the apparatus is similarly enlarged to A times for specific positive numbers A and B. In addition, the control for changing the operating conditions of the apparatus for the purpose of making the spatial scale of the movement of electrons in the plasma generation region A times and the time scale 1 / B times, that is, as a function of time t, Using the position vector r (t) of the electron (where r is a vector), when the apparatus is enlarged by A times, the state of the movement r (t) for the electron is represented by the movement A · r (t / B). A plasma processing apparatus characterized in that control for bringing the plasma processing apparatus to the state described above is performed.

In the plasma processing apparatus, especially, the two variables A and B are B = A ^p It is preferable that they are connected by the following relational expression.

In the above-mentioned plasma processing apparatus, it is preferable that ^p in the above-mentioned relational expression is particularly 0 ≦ ^p ≦ 1.

Further, in the above plasma processing apparatus,
Preferably, the intensity of the electric and magnetic fields in the plasma generation region is used as a first control factor, and the density of the neutral gas here is used as a second control factor.

Further, in the above plasma processing apparatus,
In order to control the gas density as the second control factor, it is preferable to provide an exhaust mechanism in contact with the electron forming region.

Further, in the above-mentioned plasma processing apparatus, an exhaust mechanism provided in the electron formation region and a gas discharge device provided between the electron formation region and the plasma generation region for controlling the gas density which is the second control factor. It is preferable to provide a gas shielding and electron transmission mechanism for permitting the passage of electrons from the electron formation region and preventing the passage of the processing gas from the plasma generation region.

Further, in the above plasma processing apparatus,
In order to control the acceleration of electrons as the first control factor, it is preferable to connect a voltage source for supplying a controlled electron acceleration voltage to the gas shielding and electron transmission mechanism.

Further, in the above plasma processing apparatus,
The gas shielding and electron transmission mechanism includes a grid electrode to which a voltage for accelerating the electrons in the electron formation region toward the plasma generation region is applied, and a plurality of small openings disposed adjacent to the grid electrode. And a plurality of small openings provided on the gas shielding plate, the openings corresponding to the positions and sizes of the small openings, and the electrons in the electron forming region are directed to these openings. And an electron directing electrode to which a bias voltage for forming an electric field is applied.

Further, in the above plasma processing apparatus,
The gas shielding / electron transmission mechanism is a needle-shaped electrode arranged opposite to the opening of the electron directing electrode, and cooperates with the electron directing electrode to transfer the electrons in the electron forming region to the electron forming area. It is preferable to include a needle-shaped electrode to which a bias voltage for forming an electric field directed to the opening is applied.

In the above plasma processing apparatus, it is preferable that the electron formation / acceleration mechanism includes a flat electrode having a roughened electron emission surface and a high frequency power supply for supplying high frequency power to the flat electrode. .

Further, it is preferable that the electron formation / acceleration mechanism further includes a magnetic field formation mechanism for applying a magnetic field in a vertical direction to the plate electrode.

Preferably, the plasma processing apparatus includes a light source for irradiating the electron formation / acceleration region with light.

According to another aspect of the present invention, an electron
An electron formation region having an acceleration mechanism, and a plasma generation region adjacent to the electron formation region and into which a processing gas for plasma formation is introduced, wherein the processing gas and electrons introduced from the electron formation region are A plasma generating region in which plasma is formed by the action of the plasma processing region, and a plasma processing region adjacent to the plasma generating region and provided with a mounting table for mounting a target object, wherein the target object is the plasma (1) generating electrons by an electron forming mechanism; and (2) directing the electrons toward the plasma generation region. (3) introducing the accelerated electrons formed in the electron formation mechanism into a plasma generation region; (4) reacting the accelerated electrons with the processing gas. . Forming a plasma in a plasma generation region; (5) providing a plasma processing method including a step of processing an object placed on a mounting table in the plasma processing region with the plasma; In the above-mentioned plasma processing method, in the step of (2) accelerating the electrons toward the plasma generation region, the formation conditions of the electrons are such that the acceleration of the electrons is a first control factor, and the gas density ρ is a second control factor. Preferably, it is set as a control factor.

Further, in the above-mentioned plasma processing method,
(3) In the step of introducing accelerated electrons into the plasma generation region, the accelerated electrons are allowed to pass toward the plasma generation region between the electron formation region and the plasma generation region; Preferably, the process gas in the region is prevented from passing towards the electron forming region.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A description will now be given of the similarity rule of the above-mentioned electric elements.

When the similarity rule that defines the characteristics of the gas flow field is taken into consideration, the Reynolds number Re in equation (1) may be considered.

Re = UL / ν = 3UL / (vλ) (1) where Re is the Reynolds number, ν is the kinematic viscosity coefficient, U is the representative velocity of the system, L is the representative length of the system, and v is the thermal velocity , Λ is the mean free path.

From the equation (1), for example, when the representative length L of the system is enlarged by A times, the same flow characteristics as the original system can be obtained by the operation of increasing the mean free path λ by A times. Is understood. Here, a case where A is a real number larger than 1 is considered.

The relational expression (2) is established for the mean free path λ. σλρ = 1 (2) Here, σ is the collision cross section, and ρ is the number density of the particles.

From this equation (2), it is understood that, for example, in order to multiply the mean free path λ by A, the density ρ should be reduced to (1 / A) times. At this time, the representative length of the volume occupied by one particle increases by A ^1/3 times from the equation (1).

The equation (3) holds for the number N of particles passing through the area of the cross-sectional area S during the time Δt.

N = ρvΔtS = JΔtS = QΔt (3) where J is a flux and Q is a flow rate.

From equation (3), it can be understood that when the pressure, the density ρ, and the flux J decrease to 1 / A, the flow rate Q increases A times.

The above-mentioned flow characteristics can be applied to the theory of molecular kinetics in a plasma processing apparatus, and the mean free path between heavy particles in the plasma processing apparatus can be expressed by the following equation (4). Mean free path between heavy particles is (5)
It can be expressed by an expression.

(Between heavy particles) 4λ _a σρ = 1 (4) (Between electrons and heavy particles) λ _e σρ = 1 (5) where λ _a is the mean free path of the heavy particles, and λ _e is the average of the electrons. Free process, σ is collision cross section, ρ is density.

Consider the behavior of electrons in the plasma space in the plasma processing apparatus (chamber).

The behavior of the electrons in the plasma space can be discussed from the above equations by the mean free path λ of the electrons.
In the case where λ _a is converted to A times in equation (4), that is, ρ is converted to 1 / A times, λ _e is also A times from equation (5).
From this, it is understood that the scaling of the conversion corresponds to the heavy particle system and the electron system.

Therefore, focusing on the movement r (t) of the electron (r is a vector representation), the scale of the movement is represented by A in the distance dimension.
Consider a similar enlargement by a factor of two. There are many options for time scaling, depending on the choice of electron speed or energy. Here, r is an electron position vector, and t is time. This r (t) is a position as a function of t.

The state of the plasma depends on various factors of the generation space (material properties, chamber shape, vacuum state, ball exhaust conditions,
It depends on the pressure, frequency, electric power, type and flow rate of the gas used in the external field, and the surface condition of the wall and the wafer). Have difficulty. The present invention makes it possible to apply the similarity rule to a plasma processing apparatus by focusing on electrons and controlling the behavior of the electrons. This will be further described using an exemplary case (P = 1).

When the device is magnified A times based on the state in which electrons are moving according to r (t), A · r (t
Realizing the motion of / A) means 1) making the speed of the electrons unchanged, and 2) reducing the acceleration by 1 / A times.

The reason that the electron velocity is not changed as in 1) is that the initial velocity is often determined by physical conditions such as the physical properties of the electrodes and the temperature due to the structure of the apparatus. This is because it is not easy. It is also a great advantage that the similarity conversion can be performed while maintaining the properties of the electron collision elementary process.

In order to reduce the acceleration by a factor of 1 / A as in 2), the intensity of the external field acting on the electrons may be reduced by 1 / A. It may be weakened by A times. On the other hand, when P = ^1/2 , there is an option to keep the applied external field unchanged by setting the electron velocity to A ^1/2 times. (In the case of Ar (t / A ^1/2 )) In this case, it is desirable to also control the incident energy of electrons into the plasma generation region.

For this purpose, a mechanism for increasing the energy of electrons incident on the plasma generation space is employed to generate electrons having the required energy.

As an embodiment of the present invention, a case where the above-described similarity rule is applied to a parallel plate type plasma processing apparatus in which a plasma generation chamber and a plasma processing chamber are integrated will be described.

In FIG. 1, the parallel plate type plasma processing apparatus has a plasma processing chamber 33 as described above.
The apparatus includes a plate electrode 10, a mounting table 11 opposed to the plate electrode 10, and a high-frequency power supply 12 for applying high-frequency power to the plate electrode 10.

The plasma processing chamber is provided with a gas shielding and electron transmission mechanism 13 (hereinafter, referred to as a “shielding and transmission mechanism”). And the lower plasma processing space 1
Nine and nine. A high-frequency power supply 14 for applying high-frequency power is connected to the shielding and transmitting mechanism 13.

The surface of the plate electrode 10 facing the mounting table is an electron emission surface 21, and the electron emission surface 21 is roughened. Further, a coil 15 is provided above the plate electrode 10, and the coil applies a magnetic field to the plate electrode and the electron formation / acceleration space 17. Further, a light source 31 is provided in the plasma processing chamber.
Is irradiated with a light beam in the ultraviolet region.

The temperature control mechanism 16 is provided inside the plate electrode 10.
And an exhaust means 18 for exhausting gas from an electron formation / acceleration space 17 between the parallel electrode 10 and the shielding / transmission mechanism 13.
And a processing gas supply means 20 for supplying a processing gas (for example, a mixed gas such as a fluorocarbon gas, an oxygen gas, and an argon gas) to the plasma processing space 19.

In this embodiment, the flat electrode 10 has the heating means 16. The temperature of the plate electrode 10 rises by being heated by the heating means 16 to a temperature set in consideration of Richardson Dashman's equation. [Electronic Speed Control Based on Similarity Law] In the embodiment according to the present invention, the plate electrode 10 and the mounting table 11
Is provided with a shielding and transmitting mechanism 13. The shielding and transmitting mechanism 13 shields the gas existing in the electron formation / acceleration space 17 between the flat plate electrode 10 and the mounting table 11 from moving to the plasma processing space 19, and also controls the gas in the electron formation / acceleration space 17. Is a mechanism that enables the electrons formed in the plasma processing space 19 to move to the plasma processing space 19.

A predetermined potential is applied to the shielding and transmitting mechanism 13 from the high frequency power supply 14, and an electron accelerating electric field is formed between the shielding and transmitting mechanism 13 and the plate electrode 10. Due to the structural improvement related to the plate electrode 10, the electrons efficiently formed in the electron formation / acceleration space 17 are accelerated toward the shielding / transmission mechanism 13 by the electron acceleration electric field.
The degree to which the electrons are accelerated is set from the viewpoint of the similarity rule as described above.

For example, when the motion of an electron is expanded in a similar manner as Ar · (t / A ^1/2 ) as in Example 1 of the above option, the values of the acceleration and the external field to be applied are the same. Will be used.

In the case of the first example of this option, it is necessary to set the gas pressure in the plasma generation region to a low pressure so as to be 1 / A times. This low pressure is achieved by controlling the pressure in the space by an exhaust pump connected to the exhaust means 18. When applying the similarity rule here, it is desirable to increase the incident energy of electrons in the plasma generation region. For this purpose, the potential difference for electron acceleration between the shielding and transmitting mechanism 13 and the plate electrode 10 is increased by A times.

As a result, in the system of the required scale, the same optimized plasma state as that of the system of the original scale can be maintained except for the change in the energy of the collision elementary process. Can be realized. [Determination of Amount of Scaling A Considering Elementary Process] Looking at the change of the collision cross section with energy, this amount initially increases with an increase in energy and starts to decrease at a specific energy value. Therefore, when the same energy is applied to a device where the phenomenon of lower energy that gives the same cross-sectional area actually occurs, a similar phenomenon occurs in the plasma generation region if scaling is performed to realize the higher energy. It will be. That is, the magnification A to be scaled up by considering the elementary process
Can also be determined. [Electron Energy Increasing Mechanism] For the reasons described above, it is necessary to increase the incident energy of electrons into the plasma generation region. In this embodiment, the plate electrode 10
The electron emission surface 21 has a roughened structure. In this roughened structure, the electric field is concentrated by the roughened surface, and the dissociation is promoted. That is, at the tip of the fine convex structure, the emission direction of electrons exceeds 2π in solid angle, so that the emission amount increases. Therefore, the degree of dissociation promotion can be controlled by changing the degree of the electrode surface roughness.

In this embodiment, a DC bias voltage is applied to the plate electrode 10 from the power supply 12. When a bias voltage is applied, the speed of electrons can be controlled, and as a result, the energy of the electrons increases and the dissociation can be promoted.

In this embodiment, the plate electrode 10 has
An alternating magnetic field is applied by the coil 15. This magnetic field is preferably a magnetic field perpendicular to the plate electrode 10. The coil preferably has a concentric structure. Due to this magnetic field, a current is generated between the electrodes to change the electric field, thereby facilitating dissociation, and increasing the electron emission from the electrodes by the current generated in the electrodes.

In the embodiment, for example, ultraviolet light is irradiated from the plateau 31 to the electron emission surface 21 of the electrode. If the energy of the incident photon at this time exceeds the work function of the metal material of the electrode, electron emission starts. That is, a photoelectric effect occurs. The energy of the electrons emitted from the electrode increases as the wavelength of the light is selected and the wavelength is shortened.

With the above-described structural improvement related to the flat electrode 10, it becomes possible to efficiently emit electrons into the electron formation / acceleration space 17 and form an electron flow.

Here, the following four types of electron emission acceleration methods will be described.

1) Roughening, 2) bias application, 3) magnetic field application, 4) photoelectric effect.
Two mechanisms shall be incorporated in the same device.

As a method of accelerating electron emission, which is different from the above method, there is the use of magnetron discharge. The low-pressure electron emission chamber has a pressure suitable for generating a magnetron discharge.

There is a method of periodically weakening only a magnetic field for electron confinement, which can periodically repeat generation, confinement, and release of electrons, by a specific time interval, by periodically repeating discharge on / off. In the period control, not only the rectangular wave as described above but also a smooth waveform can be controlled. The control frequency at this time is several hundred KHz to several MHz.
Of the degree. [Plasma Generating Mechanism] In FIG. 1, the electrons formed and accelerated in the electron formation / acceleration space 17 pass through the shielding / transmission mechanism 13, enter the plasma processing space 33, and are supplied from the processing gas supply means 20. Promotes the formation of a plasma of the processing gas.

In FIG. 2 to FIG.
Will be described. Referring to FIG.
Are the gas flow shielding plate 22, the plate electrode 23, and the mesh electrode 2
1 and a needle electrode 25.

As shown in FIGS. 2 to 4, the gas flow shielding plate 22 has a structure in which a large number of openings 26 are formed, and is formed of an electrically insulating panel.

The reticulated electrode 27 may have any structure as long as it has an opening through which electrons can pass. A high potential 27 is applied to the mesh electrode 27, which is higher than the plate electrode 10 and also higher than the plate electrode 23 described later. Due to this potential, an electric field is generated between the plate electrode 10 and the mesh electrode 27 in the direction in which electrons move from the plate electrode 10 to the mesh electrode 27. Electrodes 10, 2
The electrons accelerated between 7 have sufficient energy to overcome the potential barrier of the opening 26. In this example, the electrodes 10 and 23 have the same potential. The plate-like electrode 23 may be mounted on the gas flow shielding plate 22 or may be configured to be laminated and integrated with the gas flow shielding plate 22. The plate electrode 23 has an opening formed so as not to cover the opening 26 of the gas flow shielding plate 22.

The reticulated electrode 27 is provided with a needle electrode 25. At least one needle electrode 25 is arranged at a position facing the opening of each opening 26. This needle electrode 25
This prevents electrons from being gently bent in the direction of the opening 26 and from being captured and captured by the gas flow shielding plate 22 and the plate electrode 23.

An exhaust pipe 18 is connected to the electron formation / acceleration space 17. The electron formation / acceleration space 17 is exhausted by an exhaust mechanism 34 connected to the exhaust pipe 18, and the processing gas in the plasma processing space 33 is prevented from entering the electron formation / acceleration space 17 by the shielding / transmission mechanism 13. Therefore, the electron formation / acceleration space 17 can be reliably set to a low pressure necessary for realizing the electron speed control based on the similarity rule described above. [Plasma Processing] The operation of the above-described apparatus described as an embodiment of the present invention will be described.

A semiconductor wafer W to be processed is mounted on the mounting table 11 in the plasma etching processing container 30. By applying a high voltage from a DC power supply (not shown) to the mounting table, the semiconductor wafer W is attracted to the mounting table 11 by electrostatic force and fixed. By supplying the heat transfer gas from the back surface of the mounting table 11, the heat transfer efficiency between the temperature controlled mounting table 11 and the semiconductor wafer W is increased. A high frequency power supply 35 is connected to the mounting table 11 via a matching circuit (not shown), and high frequency power for bias is applied to the mounting table.

The processing gas is introduced from the processing gas supply means 20 into the plasma processing space 33 between the shielding and transmitting mechanism 13 and the mounting table 11, and the electron formation between the plate electrode 10 and the shielding and transmitting mechanism 13 is performed. The gas in the acceleration space 17 is exhausted by the exhaust means 18, and the electron formation / acceleration space 17 is set at a low pressure. The pressure value is set, for example, such that the distance between the plate electrode 10 and the shielding and transmitting mechanism 13 is substantially equal to the mean free path of electrons. By selecting the position of the gas flow shielding plate 22 of the shielding and transmission mechanism 13 and the position of the exhaust port, the movement of the processing gas in the plasma processing space 33 into the electron formation / acceleration space 17 is reduced. The pressure in the space 17 can be kept lower than the plasma forming space 33.

Electrons are efficiently emitted from the roughened electron emission surface 21 by applying a voltage from the power supply 12 between the flat plate electrode 10 and the shielding / transmission mechanism 13.
Further, the flat electrode 1 is provided on the flat electrode 10 by a coil 15.
A magnetic field perpendicular to zero is applied. With this magnetic field,
As the electric field changes, dissociation is promoted in the plasma processing region, and electron emission is promoted in the electrodes. Further, the processing gas and the electrode 10 in the space 33 are irradiated with, for example, ultraviolet light from the light source 31. By this light irradiation, light energy is given to the gas molecules, and the ionization and the dissociation of the molecules accompanying the excitation of the electronic state are promoted. In the electrodes, electron emission is promoted by the photoelectric effect. Here, the degree of dissociation of gas molecules and the amount of electron emission can be controlled by changing the irradiation amount and wavelength of light.

With the above-described structural improvement related to the flat electrode 10, it becomes possible to efficiently emit electrons into the electron formation / acceleration space 17 and form an electron flow.

The mesh electrode 27 of the shielding and transmitting mechanism 13 has
A bias voltage V2 higher than the potential of the plate electrode is applied,
In addition, a coil 15 is provided and a magnetic field in a vertical direction is applied to the plate electrode. As a result, the electrons emitted from the electron emission surface 21 are accelerated without diffusing toward the mesh electrode 27. The degree of accelerating the electrons is set to a value required from the above-described similarity rule as the initial velocity at which the electrons enter the space 33 (see Example 1 of the above option). The electron incident energy can also be set by selecting the position in the depth direction of the plasma forming space 33 to be controlled.

The plate electrode 23 of the shielding and transmitting mechanism 13 has
By applying the bias voltage V1 lower than V2, an electric field of a predetermined pattern is formed between the plate electrode 23 and the reticulated electrode 27, the needle electrode 25 added to the reticulated electrode 27, and the like. The electric field of this predetermined pattern is accelerated by the electric field between the plate electrode 10 and the mesh electrode 27, and accelerates the electrons passing through the mesh electrode 27 toward the opening 26 of the gas flow shielding plate.

The electrons that have passed through the opening 26 of the gas flow shielding plate are introduced into a processing gas in a plasma processing space between the shielding and transmitting mechanism 13 and the mounting table, and form a plasma of the processing gas.

A high-frequency bias voltage is applied from a power supply 14 between the shielding / transmitting mechanism 13 and the mounting table 11, and the plasma moves to the semiconductor wafer mounted on the mounting table, and To process.

[0086]

According to the present invention, the development of systems having different scales and the scale-up of the operation conditions are realized by making it possible to apply the similarity rules of electric elements to the plasma processing apparatus. That is, for example, the initial velocity of the electrons emitted from the plate electrode 10 tends to be determined by physical factors of the plate electrode. According to the present invention, electrons are emitted from the flat electrode 10 and are accelerated in the electron formation region to be actively controlled. Further, the present invention employs the shielding / transmission mechanism 13 and the exhaust mechanism 18 to positively control the gas pressure difference between the electron formation / acceleration space 17 and the plasma formation region 33. With this control, when changing the scale of the apparatus, the similarity rule of the electric element can be applied more accurately, and processing (etching, film formation, etc.) of a large-diameter semiconductor wafer can be performed accurately and easily. Further, the present invention provides a plasma processing space 19 by actively controlling electrons.
Can be introduced into the plasma processing space 19 with an energy corresponding to the gas type and pressure in the process and the size of the processing space. As a result, the plasma generation efficiency in the plasma processing space 19 can be increased.

Further, when the electrons are accelerated further, the collision cross section is reduced, so that the electrons can enter the plasma processing space with high energy and the deeper part of the plasma can be controlled.

Further, according to the present invention, (1) the heating means 16 is provided on the plate electrode 10, (2) the electron emission surface 21 of the plate electrode 10 is roughened, and (3) a bias voltage is applied to the plate electrode 10. (4) applying a magnetic field to the plate electrode 10;
(5) By employing at least one of the means of irradiating the electron group in the electron formation / acceleration space 17 with light, electrons can be efficiently formed in the electron formation / acceleration space 17 and plasma processing can be performed. Facilitates the application of similarity rules for electrical elements to devices.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view illustrating one embodiment of a plasma processing apparatus to which the present invention is applied.

FIG. 2 is a cross-sectional view illustrating a gas shielding and electron transmission mechanism.

FIG. 3 is a plan view illustrating a gas shielding and electron transmission mechanism.

FIG. 4 is a plan view illustrating a gas shielding and electron transmission mechanism.

FIG. 5 is a schematic explanatory view of a parallel plate type plasma processing (etching) apparatus as a related art.

[Explanation of symbols]

10: flat plate electrode, 11: mounting table, 12: high frequency power supply, 1
3 ... gas shielding and electron transmission mechanism, 14 ... high frequency power supply, 15
... Coil for generating magnetic field, 16 ... Temperature control mechanism, 17 ... Electron formation area, 18 ... Exhaust means, 19 ... Plasma formation area, 34 ... Gas source, 16 ... Heating means, 22 ... Gas flow shielding plate, 23 ... Plate Electrode, 25: needle electrode, 26: opening,
27: reticulated electrode, 30: plasma etching apparatus, 31
... Light source, 33 ... Plasma formation area

Claims (15)

[Claims] An electron formation region having an electron formation / acceleration mechanism, and a plasma generation region adjacent to the electron formation region and into which a processing gas for plasma formation is introduced, wherein the processing gas and the electron A plasma generation region in which plasma is formed by the action of electrons introduced from the formation region, and a plasma processing region adjacent to the plasma generation region and provided with a mounting table for mounting an object to be processed. The object to be processed is a plasma processing area having a predetermined processing performed by the plasma introduced from the plasma generation area, and the apparatus is similar to specific positive numbers A and B. Control to change the operating conditions of the apparatus for the purpose of making the spatial scale of the movement of electrons in the plasma generation region A times and making the time scale 1 / B times, In other words, using the position vector r (t) of the electron as a function of time t, the state of the movement r (t) of the electron is represented by A plasma processing apparatus, wherein control for bringing the apparatus into a state is performed. 2. The plasma processing apparatus according to claim 1, wherein said two variables A and B are connected by a relational expression of B = A ^p . 3. In the above relational expression, ^p is preferably 0 ≦ ^p.
3. The plasma processing apparatus according to claim 2, wherein ≤1. 4. The plasma processing apparatus according to claim 2, wherein the intensity of an electric field and a magnetic field in the plasma generation region is set as a first control factor, and the density of the neutral gas is set as a second control factor. A plasma processing apparatus operated as a control factor. 5. The plasma processing apparatus according to claim 1, wherein an exhaust mechanism is provided in contact with said electron forming region for controlling a gas density as said second control factor. Plasma processing equipment. 6. The plasma processing apparatus according to claim 1, wherein an exhaust mechanism is provided in the electron forming region to control a gas density as the second control factor; A gas shielding / electron transmission mechanism for allowing passage of electrons from the electron formation region and preventing passage of the processing gas from the plasma generation region, provided between the generation region and the electron generation region. Plasma processing equipment. 7. A plasma processing apparatus according to claim 6, wherein said gas shielding and electron transmission mechanism includes a controlled electron accelerating voltage for controlling an acceleration of electrons as said first control factor. A plasma processing apparatus, wherein a voltage source for supplying a voltage is connected. 8. The plasma processing apparatus according to claim 6, wherein the gas shielding and electron transmission mechanism includes a grid electrode to which a voltage for accelerating electrons in the electron formation region toward a plasma generation region is applied. A gas shielding plate disposed adjacent to the grid electrode and having a large number of small openings; and an opening provided on the gas shielding plate and corresponding to the position and size of the small openings. And an electron directing electrode to which a bias voltage for forming an electric field for directing electrons in the electron forming region to these openings is applied. 9. The plasma device according to claim 6, wherein the gas shielding and electron transmission mechanism is a needle-like electrode disposed opposite to an opening of the electron directing electrode, A plasma processing apparatus, comprising: a needle-shaped electrode to which a bias voltage for forming an electric field that cooperates with a directing electrode to direct electrons in the electron forming region toward the opening is applied. 10. The plasma processing apparatus according to claim 1, wherein the electron formation / acceleration mechanism includes a flat electrode having a roughened electron emission surface, a high frequency power supply for supplying high frequency power to the flat electrode. A plasma processing apparatus comprising: 11. The plasma processing apparatus according to claim 10, wherein said electron formation / acceleration mechanism further includes a magnetic field formation mechanism for applying a magnetic field in a vertical direction to said plate electrode. apparatus. 12. The plasma processing apparatus according to claim 1, further comprising light source means for irradiating the electron formation / acceleration region with light. 13. An electron formation region having an electron formation / acceleration mechanism, and a plasma generation region adjacent to the electron formation region and into which a processing gas for plasma formation is introduced, wherein the processing gas and the electron A plasma generation region in which plasma is formed by the action of electrons introduced from the formation region, and a plasma processing region provided adjacent to the plasma generation region and provided with a mounting table for mounting an object to be processed. A plasma processing apparatus having a plasma processing area in which the object to be processed is subjected to a predetermined processing by plasma introduced from the plasma generating area; (1) generating electrons by an electron forming mechanism; ) Accelerating the electrons toward a plasma generation region; (3) introducing the accelerated electrons formed in the electron formation mechanism into a plasma generation region; and (4) accelerating the electrons. By reaction with the treatment gas and the child. Forming a plasma in the plasma generation region; and (5) processing the object placed on the mounting table in the plasma processing region with the plasma. 14. The plasma processing method according to claim 13, wherein in the step of (2) accelerating the electrons toward a plasma generation region, the formation conditions of the electrons include: A plasma processing method, wherein a gas density ρ is set as a second control factor as a control factor. 15. The plasma processing method according to claim 13, wherein in the step of (3) introducing accelerated electrons into a plasma generation region, the accelerated electrons are accelerated between the electron formation region and the plasma generation region. A plasma processing method, wherein electrons are allowed to pass toward a plasma generation region, and a processing gas in the plasma generation region is prevented from passing toward the electron formation region.