KR100391180B1 - Method and apparatus for plasma chemical treatment of a substrate surface - Google Patents

Abstract

The present invention relates to an apparatus and method for plasma chemical treatment of a substrate surface, and more particularly, to an apparatus and method for plasma chemical treatment of a substrate surface using high frequency capacitive discharge in order to increase process rate and uniformity. It is about.

To this end, the present invention provides a plasma source for activating a gas inlet into which a process gas is introduced and a process gas introduced into the gas inlet into a high frequency capacity discharge when treating a substrate surface, A substrate holder for holding a substrate processed by the process gas activated by the plasma source, a RF generator for supplying power to the plasma source and having a matching device installed at one side thereof; It includes a polarity conversion variable DC power supply for changing the polarity and the wave trap connected to the plasma source for controlling the voltage drop on the electrode side of the plasma source and a solenoid installed around the plasma source to vary the magnetic field of the plasma source. .

Description

Plasma chemical treatment method and apparatus for substrate surface {METHOD AND APPARATUS FOR PLASMA CHEMICAL TREATMENT OF A SUBSTRATE SURFACE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma chemical treatment apparatus and method for a substrate surface, and more particularly, to a plasma chemical treatment apparatus and method for a substrate surface that can be used in the semiconductor industry and applied to other electrical and mechanical engineering fields.

Methods and apparatus for plasma chemical treatment processes for treating substrate surfaces by inducing a process gas by using induction discharge are well known.

However, in the plasma chemical treatment process using the induced discharge, the plasma parameters are very uneven, and there is a low density of electrons, resulting in uneven process gas activity. Thus, the surface of the substrate is treated unevenly.

The discharge can be improved if the position of the discharge electrode coil can be closer to the gas flow path. Accordingly, a funnel-shaped discharge electrode coil in which a substrate is disposed at the bottom and a gas supply device is disposed at the top (Russia Invention No. 732634, H01L 21/00, 1979) has been proposed. In the device, process uniformity is improved because the process gas passes through the plasma region on the shaft from the top of the coil. The process gas around the coil is further activated at the bottom of the flow path so that the uniformity of the active gas reaching the substrate surface is increased by the plasma diffusion process.

However, the present invention does not provide a method for adjusting the process uniformity required to maintain the required quality of the treatment, there is a disadvantage that almost no change in the process rate.

Accordingly, a plasma chemical treatment apparatus using capacity discharge has been developed. In the case of using the capacitive discharge, the surface of the electrode in contact with the plasma builds up with an electrode sheath, where a significant potential difference occurs.

Thus, ions collide with the electrode surface and generate a secondary electron beam having an energy of 10 ² -10 ³ eV and enter the plasma to activate all process gases. There are many plasma chemical processing apparatuses using such capacitive discharge. (E.g. Goto HH et al., IEEE Transactions on Semiconductor Manufacturing, 1991, V.4, No. 2, pp. 111-121). However, the above devices do not consider the balance between the gas supply dynamics and the discharge structure, which may greatly affect the degree of activation of the process gas, and thus, there is no improvement in uniformity and process rate in treating the substrate surface.

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above problems, and an object of the present invention is to provide a plasma chemistry treatment apparatus and method which can simultaneously increase process rate and process uniformity in a process of etching or depositing a substrate surface. .

1 is a schematic diagram of a plasma chemical processing apparatus according to one embodiment of the present invention;

2 is a cross-sectional view of an embodiment of the central electrode or the external electrode of FIG. 1.

3 is a cross-sectional view according to another embodiment of the central electrode or external electrode of FIG.

4 is a schematic diagram of a plasma chemical processing apparatus equipped with a plurality of plasma sources according to an embodiment of the present invention.

5 is a plan view of the plurality of plasma sources of FIG.

<Description of the symbols for the main parts of the drawings>

10: gas inlet 12: gas inlet sleeve tube

14: gas corrector 20: plasma source

22: center electrode 24: external electrode

30: substrate holder 32: solenoid

34: base material 40: high frequency power supply

42: high frequency oscillator 44: input parallel capacitor

46: output blocking capacitor 50: matching device

60, 62: Wave trap 64, 66: polarity conversion variable DC power supply

68: variable blocking capacitor 70: high frequency power blocking capacitor

72: inductor 74: variable resistor

76: switch

In order to achieve the above object, the plasma chemical processing apparatus of the substrate surface according to the present invention is a high-frequency capacitive discharge (gas discharge) of the gas inlet, a process gas introduced into the process gas, the process gas introduced into the gas inlet A plasma source for activating the plasma source, a substrate holder for holding a substrate processed by the process gas activated by the plasma source, a power supply to the plasma source, and a matching device on one side thereof. A high frequency generator (RF generator) installed, a wave trap connected to the plasma source for controlling the voltage drop of the electrode side of the plasma source, a polarity converting variable current power source connected to the wave trap to change the polarity, and a circumference of the plasma source It may be configured to include a solenoid which is installed in the variable magnetic field of the plasma source. .

The plasma source is composed of a center electrode and an external electrode whose surface is formed of a conductor, and is coaxially formed. The solenoid may be divided into two so as to have an opposite field.

The center electrode is the and the lower end may be formed in a round shape, at least one of the outer electrode and the center electrode may be formed placing the winding in order to expand the reacting surface area, the surface hole to convert a radial discharge structure It can be applied to the formed dielectric film.

In addition, the matching device may use a transformer-type matching device.

The substrate holder may be connected to one side of the matching device through a high frequency power cut-off capacitor and jointly connected to the external electrode through a polarity conversion variable DC power source capable of changing a polarity with a wave trap and connected in parallel with the plasma source. Can be enclosed with solenoids.

The substrate holder may be connected to a circuit in which the blocking capacitor is connected in parallel to an inductor, a variable resistor, and a switch connected in series with each other, and the inductor is configured to resonate with a minimum value of the blocking capacitor at an operating frequency.

One or more plasma sources may be used, and the one or more plasma sources may be arranged in parallel, and the parallel arrangement may place one of the plasma sources at the center and the other plasma source may have a circular area around the central plasma source. It can be arranged to surround, and the discharge mode of each plasma source can be adjusted independently.

The plasma sources may be connected to a common high frequency power source in parallel to the central plasma source and include a variable blocking capacitor at a portion where each electricity is introduced, and the substrate holder may be configured to move in an axial direction.

In addition, in order to achieve the object as described above, the plasma chemical treatment method of the surface of the substrate according to the present invention is activated by supplying a process gas along the plasma source excited by high frequency active discharge across the flow of gas A process gas is activated and treated by a high frequency capacitive discharge, including a gas activity distribution control step of controlling a distribution of gas activity obtained at an outlet by an activation step and a deformation of the longitudinal structure of the electrode. Supply to the area.

In the activation step, the plasma source is composed of a coaxially arranged central electrode and an external electrode, and the use of the coaxial electrode discharge, gas pressure adjustment, and a variable DC power source capable of changing the wave trap and polarity is connected to the electrode. Thus, the plasma source and the distribution of the discharge's radial structure can be controlled by controlling the adjacent voltage drop of the electrode.

In the activation step, the plasma source is composed of a coaxially arranged central electrode and an external electrode, and the discharge's radial structure is controlled by the use of the coaxial electrode discharge and the adjustment of the electrode adjacent voltage drop and the gas pressure. The distribution of can be adjusted.

The radial discharge structure may be controlled by applying a uniform coating having a secondary electron emission coefficient different from the materials constituting the inner electrode and the outer electrode.

In order to change the discharge structure of the discharge, a plasma source having a polarity converting variable DC power source capable of changing the polarity of the wave trap and the polarity and a magnetic field of a short DC or AC solenoid may be applied along the axial direction of the plasma source. The solenoid may be formed of two parts generating opposite polarities to apply a magnetic field in the longitudinal direction of the plasma source.

The gas active distribution control step may control the distance between the substrate holder mounted to hold the substrate to be treated with the process gas and the plasma source according to the life duration of the process gas.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

However, the following examples are only for illustrating the present invention in detail and do not limit the scope of the present invention. All simple modifications and variations of the present invention can be considered to be included within the scope of the present invention.

1 is a schematic diagram of a plasma chemical processing apparatus according to an embodiment of the present invention.

As shown in FIG. 1, the plasma chemical processing apparatus according to the present invention includes a gas inlet 10, a plasma source 20, a substrate holder 30, a high frequency power supply 40, a matching device 50, and a wave trap. (60, 62), polarity conversion variable DC power supply (64, 66), solenoid (26, 32).

The gas inlet part 10 includes a gas inlet sleeve tube 12 and a gas corrector 14 as a part into which a process gas is introduced.

The process gas flowing into the gas inlet sleeve tube 12 flows to the discharge region A via the gas collector 14.

The discharge region A is a region where discharge is generated by the plasma source 20. The process gas introduced into the discharge region A is activated by the plasma generated by the plasma source 20 to perform a chemical treatment for etching or depositing the substrate 34 on the substrate holder 30.

The plasma source 20 is composed of a central electrode 22 and an external electrode 24.

The center electrode 22 and the external electrode 24 are coaxially disposed, and a discharge structure is formed between the electrodes 22 and 24 to cross the flow of the process gas. .

The discharge structure is a type of discharge formed in the discharge region A and is formed adjacent to the central electrode 22 and the external electrode 24 in which high-speed ions flow from the plasma and have a flow of secondary electrons that move in the opposite direction. It means a plasma region in which electrons formed between a region and the sheath region collide with heavy particles to lose energy.

The process gas is activated due to the collision of electrons excited in the discharge region A. The initial process gas is charged with negative and positive molecules, atoms, and dissociated products of the molecules and atoms in the excited state. It becomes ionized particles in ionic form and the particles are called active species.

As described above, a conventional apparatus using inductive discharge or a device using capacitive discharge has a disadvantage in that the discharge structure cannot be adjusted to be suitable for a process use.

Accordingly, according to the plasma chemical processing apparatus of the present invention, the optimum active species shape and distribution can be obtained by controlling the discharge structure.

The coaxial configuration of the plasma source 20 is related to the superiority of the discharge region and the regulation of the discharge structure is related to the absolute size of the region.

The discharge structure can be roughly divided into a longitudinal structure and a radial structure of the discharge region A, and the longitudinal structure and the radial structure of the discharge region A are changed according to the purpose of the process.

The longitudinal structure may be changed by adjusting the length of the plasma source 20, adjusting the distance between the substrate holder 30 and the plasma source 20, and adding a solenoid 26 to the plasma source 20. have.

The length of the plasma source 20 may be achieved by adjusting the lengths of the center electrode 22 and the external electrode 24. The acceleration of gas activation is due to the flow of gas along the surfaces of the electrodes 22 and 24.

The distance between the substrate holder 30 and the plasma source 20 may be achieved by moving the substrate holder 30 in the axial direction.

The substrate holder 30 may be formed in a flat plate shape, and the substrate holder 30 may be vacuum sealed by a variable corrugation box and moved in an axial direction by manual or mechanical driving means.

In addition, the solenoid 26 may be added to one side of the plasma source 20 to change the discharge structure in the longitudinal direction.

On the other hand, the radial structure of the discharge region (A) is the control of the electrostatic voltage drop of the plasma source 20, the gas pressure control in the discharge region (A), the secondary electron emission coefficient of the plasma source 20 It can be changed by coating with other materials, by changing the surface area of the plasma source 20 and by adding the solenoid 26.

Hereinafter, the configuration according to the present invention for changing the radial structure of the discharge region (A) will be described in detail.

In consideration of the shape of the substrate in chip production, the plasma source 20 is coaxial, and in the high frequency capacitive discharge, the thickness of the discharge seeds is inversely proportional to the pressure of the process gas. Adjusting the pressure of the process gas can change the thickness of the active region sheath, thereby allowing the surrounding gas to be further activated. The gas pressure regulation can make a pre-determined correction to connect and partially overlap the two opposing active regions to smooth the shape of the active distribution of the gas and to offset the effects of diffusion that interferes with the uniformity of the substrate.

The redistribution of the active region is performed by the circuit of the polarity converting variable current power supply 64 which can change polarity with the wave trap 60 connected in series with the high frequency discharge. The wave trap 60 prevents leakage of high frequency power but does not interfere with direct current of the circuit. This adjustment is possible only when the discharge electrode is electrically connected to the plasma.

Therefore, the plasma source 20 according to the present invention should have electrodes 22 and 24 having electrically conductive surfaces.

The radial discharge structure may be changed by adjusting surface areas of the center electrode 22 and the external electrode 24. Depending on the application, the electrodes 22 and 24 may be bent to increase the surface area of the electrodes 22 and 24.

2 is a cross-sectional view of an embodiment of a central electrode or an external electrode according to the present invention. As shown in FIG. 2, the center electrode 22 or the external electrode 24 may be formed to have a cross-section in a wavy shape and may also be formed in a wrinkled shape.

When the surface areas of the electrodes 22 and 24 are formed to be wide, the gas activity of the plasma chemical processing apparatus is increased by changing the current density of the electrode and thus changing the voltage drop. This increases the process rate since the activity of the gas increases .

The magnitude of the electrode adjacent voltage drop also depends on the properties of the electrode base material.

The voltage drop decreases, particularly as the secondary electron emission coefficient increases.

3 is a cross-sectional view of an embodiment of a center electrode or an external electrode according to the present invention.

As shown in FIG. 3, materials having different secondary electron emission coefficients are uniformly coated on the surface of the central electrode 22 or the external electrode 24, and the surfaces of the electrodes 22 and 24 are perforated. It can be applied with a dielectric film.

Applying the electrodes 22 and 24 reduces the voltage drop near the electrodes 22 and 24 and maintains the discharge characteristics of the electrode itself. This reduces the magnitude of the redistribution of subsequent voltage drops and facilitates adjustment.

On the other hand, the lower end of the center electrode 22 may be formed in a round shape, because the activity distribution can be improved by adjusting the intensity of the electric field of the end of the center electrode.

In order to increase the gas activity in the discharge region A, the plasma source 20 has an axial magnetic field with a short solenoid 26 of direct current or alternating current. This magnetic field is advantageous for low pressure high frequency discharge because it can be combined with the discharge electric field to increase the ionization of the plasma twice and thus increase the activity of the gas. Therefore, the present invention can further increase the process rate.

In addition, the strength of the magnetic field in the solenoid 26 (shorter than the inner diameter) increases toward the radial periphery to help reach the predicted change in gas activity required to obtain a uniform process of the substrate. When the solenoid 26 is divided into two parts to which the power is applied in the opposite direction, the solenoid 26 is formed without the axial magnetic field, and the discharge is fixed to the part. The method is used to leave a space in solenoid 26 and to avoid a high ionization discharge mode. The replaced magnetic field increases the azimuthal uniformity of the process gas flow.

The transformer matching device 50 provides a ground potential to the cabinet of the high frequency oscillator 42. This is important from the point of view of electrical safety and may limit the ground potential and the intermediate potential of the other external electrode 24 around the chemical treatment apparatus.

Connecting the secondary coil of the matching device 50 to the substrate holder 30 through the high frequency power cut-off capacitor 70 enables the supply of a high frequency potential to electrodes required for various processes of the substrate.

When the energy of ion bombardment is required such as deposition, the high frequency power blocking capacitor 70 can be reduced to a minimum. This approach causes the ion energy (Ei) to be about 10 ¹ eV (electron-Volts). When adding the high-frequency power blocking capacitor 70, the inductor 72 and the variable resistor 74 is the circuit to smooth to Ei ~ 10 ⁰ eV, such as a floating potential (floating potential) of the plasma adjacent to the potential of the substrate holder 30 Can be raised slowly.

When the positive polarity is supplied from the polarity converting variable current power supply 66 through the wave trap 62 to the substrate holder 30, the potential of the substrate 34 is equal to the plasma potential in the discharge region A. You can make it together. In this case, the thin film may be smoothly deposited on the substrate 34. If the thin film is a dielectric, the potential of the substrate holder 30 will be gradually lowered to the floating level during the process. Slow ion bombardment continued at this stage does not damage the thin film. This is because a thin film is smoothly formed on the substrate 34 up to this step and is stably protected by the newly deposited atomic layer.

On the other hand, in order to uniformly plasma-chemically treat the surface of the large substrate 34 having a diameter of 500 mm or more, a low pressure due to the above-described glow discharge is required. However, very low pressures are undesirable because they hinder the technical process to be performed. In this case, a plurality of coaxial plasma sources 20 can be used.

4 is a schematic diagram of a plasma chemical processing apparatus equipped with a plurality of plasma sources according to an embodiment of the present invention, and FIG. 5 is a plan view of the plurality of plasma sources.

As shown in Figs. 4 and 5, the plurality of plasma sources 20 are adjusted to obtain local uniform plasma of all plasma sources 20 therein, and an external circuit is used to estimate the predicted gas activity. To generate a change, a more active plasma must be created.

The plurality of plasma sources 20 may be connected to one common high frequency oscillator 42 and a variable blocking capacitor 68 may be installed at each of the electrical inputs to independently control the discharge mode.

The substrate holder 30 may be enclosed by an additional solenoid 32, and an inductor 72, a variable resistor 74, and a switch 76 in parallel to the high frequency power blocking capacitor 70 of the substrate holder 30. Circuits connected in series may be connected.

In this case, the inductor 72 resonates with the lowest value of the blocking capacitor at the operating frequency.

The operation of the plasma chemical processing apparatus according to the embodiment of the present invention is as follows.

The distance between the substrate holder 30 and the plasma source 20 on which the substrate 34 is disposed is adjusted, and the distance is determined in consideration of the active species life of the gas involved in the process.

The output voltages of the polarity converting variable current power supplies 64, 66 are adjusted in accordance with the techniques of those skilled in the art to which the present invention relates.

A cooling switch (not shown) of the central electrode 22, the external electrode 24, and other components is operated to evacuate the reactor vessel of the plasma chemical processing apparatus.

The process gas is injected into the gas inlet sleeve 12 and the high frequency oscillator 42 is switched off.

After discharge, the electric supply to the solenoids 26 and 32 is started in accordance with the technical procedure, and the gas pressure and the polarity conversion variable DC power supply 64 and 66 discharge matching are adjusted.

An input parallel capacitor 44, an output interrupting capacitor 46, and a high frequency power interrupting capacitor 70 are used, and the inductor 72 and the variable resistor 74 are operated in accordance with the process.

During the process, the voltage drop in front of the substrate 34 and the concentration of plasma ions are continuously measured to obtain accurate process parameters according to the technical procedure.

As described above, the present invention can increase the activity by prolonged contact between the process gas and the coaxial capacitive discharge in the plasma chemistry process, and can control the activity distribution arbitrarily by controlling the plasma potential, so that the process chemistry and process uniformity are high. A processing apparatus and method are provided.

In addition, the use of an AC power source replaces the use of an expensive DC power source to provide a plasma chemical processing apparatus and method with increased economics.

Claims (20)

A gas inlet through which process gas is introduced; A plasma source for activating the process gas introduced into the gas inlet by a high frequency capacity discharge; A substrate holder for holding a substrate processed by the process gas activated by the plasma source; An RF generator for supplying power to the plasma source and having a matching device installed on one side thereof; A polarity converting variable current power supply connected to the wave trap connected to the plasma source so as to change a polarity and a voltage of the wave trap connected to the plasma source for controlling the voltage drop of the electrode side of the plasma source; And And a solenoid disposed around the plasma source to vary a magnetic field of the plasma source. The plasma chemical processing apparatus of claim 1, wherein the plasma source comprises a center electrode and an external electrode whose surface is formed of a conductor, and is formed coaxially with each other. The plasma chemical processing apparatus of claim 1, wherein the solenoid is divided into two so as to have an opposite field. 3. The plasma chemical processing apparatus of claim 2, wherein the center electrode is formed in a round shape at a lower end thereof. 3. The plasma chemical processing apparatus of claim 2, wherein at least one of the external electrode and the central electrode is formed to bend to expand the reaction surface area. 3. The plasma chemical processing apparatus of claim 2, wherein at least one of the external electrode and the central electrode is coated with a dielectric film having a hole formed on the surface thereof. 7. The plasma chemical processing apparatus of any one of claims 1 to 6, wherein the matching device is a transformer-type matching device. The external electrode according to any one of claims 1 to 6, wherein the base holder is connected to one side of the matching device through a high frequency power cut-off capacitor and has a polarity conversion variable DC power source capable of changing a polarity with a wave trap. Plasma chemical treatment apparatus for the surface of the substrate, characterized in that connected to the joint in parallel with the plasma source. 9. The apparatus of claim 8, wherein the substrate holder is surrounded by a solenoid. 10. The method of claim 9, wherein the substrate holder is connected to a circuit in which the blocking capacitor is connected in parallel to the inductor, variable resistor, switch connected in series with each other, the inductor is configured to resonate with the minimum value of the blocking capacitor at the operating frequency A plasma chemical treatment apparatus for a substrate surface. The plasma chemical processing apparatus of any one of claims 1 to 6, wherein one or more plasma sources may be used, and the one or more plasma sources may be disposed in parallel. 12. The method of claim 11, wherein the parallel arrangement is arranged to center one of the plasma source and the other plasma source to surround the central plasma source outer periphery in a circular region, the discharge mode of each plasma source is independent Plasma chemical treatment apparatus for the surface of the substrate, characterized in that can be adjusted to. 13. The plasma chemical processing apparatus of claim 12, wherein the plasma sources include a variable blocking capacitor connected to a common high frequency power source in parallel to the central plasma source and to which respective electricity is introduced. . 7. The plasma chemical processing apparatus of any one of claims 1 to 6, wherein the substrate holder is movable in an axial direction. An activation step of supplying and activating a process gas along a plasma source excited by high frequency active discharge across the flow of gas; The process gas is activated and supplied to the treatment region by a high frequency capacitive discharge, including a gas activity distribution control step of controlling the distribution of gas activity obtained at the outlet by deformation of the longitudinal structure of the electrode. Plasma chemical treatment method of the surface of the substrate. The method of claim 15, wherein in the activation step The plasma source is composed of a coaxially arranged central electrode and an external electrode, and the electrode adjacent voltage drop by connecting a variable DC power source that can change the polarity of the wave trap and the use of the coaxial electrode discharge, gas pressure adjustment Plasma chemical treatment method of the surface of the substrate, characterized in that for controlling the distribution of the plasma source and thereby the radial discharge structure (discharge's radial structure). The method of claim 16, wherein the radial discharge structure of the discharge is characterized in that the coating is controlled by a uniform coating having a secondary electron emission coefficient different from the material constituting the inner electrode and the outer electrode. Plasma chemical treatment method of the surface of the substrate. 17. The method of claim 16, wherein a plasma source having a variable direct current power source capable of changing a wave trap and a polarity connected to an electrode, and a magnetic field of a short direct current or alternating solenoid in accordance with an axial direction of the plasma source to change the discharge structure of the discharge. Plasma chemical treatment method of the surface of the substrate, characterized in that the application. 17. The plasma chemical treatment of claim 16, wherein the solenoid is formed of two parts which generate opposite polarities to change the discharge structure of the discharge, and applies a magnetic field in the longitudinal direction of the plasma source. Way. The method of claim 15, wherein the gas active distribution control step Plasma chemical treatment of the surface of the substrate, the distance between the substrate holder and the plasma source mounted to hold the substrate to be treated with the process gas according to the life duration of the process gas is adjusted. Way.