KR20070025823A - Plasma generation apparatus for making radical effectively - Google Patents

Abstract

A plasma generation apparatus for effective creation of a radical is provided to obtain high film quality by preventing damage of a thin film caused by an ion impact in a PECVD(Plasma Enhanced Chemical Vapor Deposition) device. In a plasma generation apparatus(100) for effective creation of a radical, a chamber(110) has a reaction space for forming plasma inside the chamber(110). A substrate receiving unit is located inside the chamber(110). An RF(Radio Frequency) electrode(140) is installed on an upper part of the substrate receiving unit. An RF power source(160) is connected to the RF electrode(140). A matcher(164) matches an impedance between the RF power source(160) and the RF electrode(140). A gas distribution unit is installed between the RF electrode(140) and the substrate receiving unit. The gas distribution unit is insulated from the RF electrode(140). The gas distribution unit has a plurality of through parts shielded by a plasma sheath. A gas inflow pipe(170) supplies gas to a space between the RF electrode(140) and the gas distribution unit.

Description

Plasma generation apparatus for making radical effectively

1 is a schematic configuration diagram of a general PECVD apparatus

2 is a schematic structural diagram of a plasma generating apparatus according to an embodiment of the present invention;

3 to 6 show several types of gas distribution plates

7 is a view showing the relationship between the injection hole diameter and the sheath thickness in the PECVD apparatus

8 and 9 show various types of mesh-type gas distribution plates

10 shows a sheath formed around a mesh;

* Explanation of symbols for main parts of drawings *

100: plasma generator 110: chamber

120: susceptor 122: susceptor support

130: gas distribution plate 132: injection hole

134: injection slit 138: mesh-type gas distribution plate

138a: Frame 138b: Mesh

140: RF electrode 150: insulating member

160: RF power supply 164: matcher

170: gas inlet pipe 180: exhaust port

The present invention relates to a plasma for manufacturing a display device or a semiconductor device such as a liquid crystal display (LCD), a field emission display (FED), an organic light emitting diode device (OLED), etc. The present invention relates to a plasma generator that processes a glass or a wafer (hereinafter, referred to as a substrate) by using the same.

FIG. 1 schematically illustrates a general configuration of a Plasma Enhanced Chemical Vapor Deposition (PECVD) apparatus for converting a raw material into a plasma state and then depositing a thin film on a substrate using the plasma generator as an example.

In this regard, the PECVD apparatus 10 includes a chamber 11 defining a constant reaction region, a susceptor 12 positioned inside the chamber 11 and having a substrate 30 disposed on an upper surface thereof, and the susceptor 12. Gas distribution plate 13 for injecting the raw material to the top of the), the RF electrode 15 located on the upper portion of the gas distribution plate 13, the gas inlet pipe connected to the central portion of the RF electrode 15 (16), an exhaust port (19) formed at the bottom of the chamber (11) to exhaust residual gas.

The RF electrode 15 is connected to the RF power source 17, and a matcher 18 for matching impedance is provided between the RF power source 17 and the RF electrode 15.

The susceptor 12 is supported by the susceptor support 12a, and a driving device (not shown) is connected to the susceptor support 12a to move the susceptor 12 up and down.

The gas distribution plate 13 has a peripheral portion thereof coupled to the RF electrode 15 to form a buffer space 14 between the RF electrode 15, and the gas distribution plate 13 and the RF electrode 15 are usually Both are in an electrically connected state because they are made of anodized aluminum.

The chamber 11 is normally grounded, and the gas distribution plate 13 and the RF electrode 15 are insulated from the chamber 11 using the insulating member 20.

Looking at the process of generating a plasma in the PECVD apparatus 10 having such a configuration as follows.

First, a process atmosphere is formed in the chamber 11 through vacuum pumping, and then the raw material is injected into the upper portion of the susceptor 12 through the gas inlet pipe 16 and the gas distribution plate 13. At the same time, RF power is applied to the RF electrode 15. The RF power is transmitted to the gas distribution plate 13 electrically connected to the RF electrode 15, and the RF power delivered to the gas distribution plate 13 is grounded susceptor. The RF electric field is generated between (12) and the electrons in the raw material are accelerated to collide with the neutral gas by the generated RF electric field.

Due to the collision, the raw material is in a plasma state, which is a mixture of electrons and ions, and even when it is not dissociated into ions, the active energy of the excited state is generated due to the collision energy.

Since the rate of dissociation of the raw material into the plasma state is very low, such as 10 ^-5 to 10 ^-6 , the density of the active species in the neutral state is much higher even though plasma is generated. Is used.

However, when plasma is generated in the PECVD apparatus 10, a sheath is generated between the plasma and the substrate. Sheath is a phenomenon caused by the difference in mobility between electrons and ions at the interface between the plasma and the surrounding material, and a kind of built-in electric field is formed between the electrons reaching the interface first and the cations on the plasma surface. It serves to maintain the plasma bulk (bulk) density metastable.

However, sheaths not only play this positive role but also accelerate the cations trapped in the sheath, which can cause ion bombardment to deteriorate the product or generate unnecessary particles. In the thin film deposition process, the deposited thin film is damaged.

An object of the present invention is to provide a plasma generator that improves the film quality by appropriately controlling electron energy and ion energy to minimize ion impact.

The present invention to achieve the above object, the chamber having a reaction space for plasma formation therein; Substrate placing means located in the chamber; An RF electrode installed on the substrate mounting means; An RF power source connected to the RF electrode; A matcher for matching an impedance between the RF power supply and the RF electrode; Gas distribution means disposed between the RF electrode and the substrate placing means, the gas distributing means having a plurality of penetrating portions insulated from the RF electrode and shielded by a plasma sheath; It provides a plasma generating device comprising a gas inlet pipe for supplying gas to the space between the RF electrode and the gas distribution means.

The penetrating portion of the gas distribution means is an injection hole having a maximum diameter (D) of 2 times or less than the plasma sheath thickness (S), wherein the maximum diameter (D) of the penetrating portion is preferably 1 µm or more and 11 mm or less.

In addition, the penetrating portion may be an injection slit having a width less than twice the plasma sheath thickness S.

It may include a position adjusting means for adjusting the distance between the RF electrode and the gas distribution means, wherein the distance between the gas distribution means and the RF electrode is preferably 10mm to 100mm.

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

2 is a cross-sectional view schematically showing the configuration of a plasma generating apparatus 100 according to an embodiment of the present invention.

The biggest feature of the plasma generating apparatus 100 according to the embodiment of the present invention is that the RF electrode 140 and the gas distribution plate 130 are insulated from each other and have a gas distribution having an injection hole 132 having an appropriate size. The plate 130 divides the interior of the chamber into a plasma and active species generating region (I, hereinafter generated region) and a plasma and active species reacting with substrate 30 (II, hereinafter referred to as reaction region). to be.

That is, the plasma and the active species are generated in the generation region I between the RF electrode 140 and the gas distribution plate 130, and the plasma and the active species generated between the gas distribution plate 130 and the susceptor 120. And diffuses into the reaction zone (II) to react with the substrate (30).

Since the gas distribution plate 130 and the RF electrode 140 must be insulated from each other, the periphery of the gas distribution plate 130 is not connected to the RF electrode 140 as in the related art, and a chamber (using a separate support member 131) 110) It is fixed at a predetermined position inside. The support member 131 may be fixed to the inner wall of the chamber 110, or may be moved up and down by a driving means for adjusting the gap between the RF electrode 140 and the gas distribution plate 130, as will be described later. .

In addition, an annular or ring-shaped insulating member 150 is installed on the upper periphery of the gas distribution plate 130 and the RF electrode 140 is mounted on the insulating member 150.

3 and 4, the gas distribution plate 130 may have a plurality of injection holes 132 formed in a square or circular flat plate base material, and a plurality of injections as shown in FIGS. 5 and 6. The slit 134 may be formed.

The gas distribution plate 130 is preferably aluminum, aluminum alloy, anodized aluminum, but may be an insulating material such as ceramic, Si, SiC, SiO ₂ .

The gas distribution plate 130 should be manufactured to have a thickness of at least 1 μm or more in order to maintain the minimum strength, but preferably made of a thickness t of 50 mm or less in view of weight or cost.

In this case, when manufacturing the thickness of 1mm or more and 50mm or more, it is preferable to produce a shower head type in which the injection hole 132 or the injection slit 134 is formed in the flat plate base material as shown in Figs. In the case of fabrication of less than a thickness, it is preferable to fabricate a mesh type (see FIGS. 8 and 9) of a network structure described later, but is not necessarily limited thereto.

The principle of controlling ion energy and electron energy using the plasma generating apparatus 100 according to the embodiment of the present invention is as follows.

Plasma and active species generated in the generation region (I) diffuse into the reaction region (II) through the injection hole 132 or the injection slit 134 of the gas distribution plate 130, and the active species are in the excited state Since it is electrically neutral, it can pass through the injection hole 132 without an electric sanction.

However, since ions and electrons in the plasma carry electricity, they are affected by the sheath near the injection hole 132 or the injection slit 134. Usually, ions are more affected because ions diffused into the sheath are trapped by the sheath electric field and collide with surrounding materials or neutral gases, converting to neutral particles or degrading ion energy due to recombination.

On the other hand, in the PECVD apparatus, since the high energy ions in the generation region (I) do not diffuse into the reaction region (II) to reduce the ion impact on the thin film, the injection hole of the gas distribution plate 130 as shown in FIG. 132) It is desirable that the interior is completely covered by the sheath so that it is equipotential with the sheath.

Therefore, when the maximum diameter of the injection hole 132 is D and the thickness of the sheath (indicated by the dotted line) formed near the injection hole is S, it is preferable that D ≦ 2S. That is, it is preferable that the injection hole 132 is a condition in which bulk plasma or glow discharge does not occur.

By using the gas distribution plate 130, the ions of the plasma generated in the generation region (I) are trapped by the sheath and are restricted from being diffused into the reaction region (II). Even in the case of ions diffused through the sheath, Is greatly reduced.

Therefore, since the ion density and ion energy in the reaction region (II) are significantly lowered, the damage to the thin film due to the ion impact is reduced, thereby obtaining excellent film quality.

In order to determine the maximum diameter D of the injection hole 132, it is important to check the thickness S of the sheath. In the present invention, the Debye length (λ _D ), which is frequently used in relation to plasma, is used. By suggesting the preferred sheath thickness (S).

In general, Debye length (λ _D ) can be expressed by the following equation.

λ _D = 7400 (T _e / n _e ) ^1/2 [mm]

Where T _e is the electron temperature (eV) and n _e is the plasma density (cm ^-3 ). However, conventional sheath thickness (S) and λ _D is S ≒ it is known that the relation of 10λ _D, the electron temperature (T _e) the higher the plasma density (n _e) has a lower sheath thickness (S) thick load Able to know.

In a capacitively coupled plasma (CCP) generator using a plate electrode, the electron temperature Te generally has a value of 3 to 10 eV and the plasma density n _e is 5 * 10 ⁸ to 1 *. ^Has a value of 10 ¹⁰ cm ^-3 .

Therefore, by using T _e and n _e in this range, λ _D and S can be obtained as shown in the following table, and the diameter D (= 2S) of the injection hole can be obtained using this.

[table]

T _e (eV) n _e (cm ^-3 ) λ _D (mm) S (mm) D (mm) t (mm) 3 5 * 10 ⁸ 0.573 5.732 11.464 28.66 3 1 * 10 ¹⁰ 0.013 0.128 0.256 0.64 10 5 * 10 ⁸ 0.105 1.047 2.093 5.235 10 1 * 10 ¹⁰ 0.023 0.234 0.468 1.17

Since the thickness t of the gas distribution plate 130 is preferably 5 S or more, the table shows a case where t = 5 S.

Therefore, in the PECVD apparatus, for example, when using a plasma having an electron temperature and density of 3 eV and 1 * 10 ¹⁰ cm ^-3 , respectively, it is preferable to use the gas distribution plate 130 having a maximum diameter D of the injection hole of 0.26 mm or less. .

In addition, in a PECVD apparatus using plasma having an electron temperature and a density of 3 eV and 5 * 10 ⁸ cm ^-3 , it is preferable to use a gas distribution plate 130 having a maximum diameter D of about 11 mm or less.

Meanwhile, when the diameter of the injection hole 132 is set to D> 2S, the injection hole 132 may be effectively applied to an etchant for etching the thin film. The diameter should be large so that ions can pass through the injection hole 132 without being trapped in the sheath region.

On the other hand, the plasma density (n _e ) is affected by the gap between the gas distribution plate 130 and the RF electrode 140, it is preferable that the gap between both is 10mm or more and 100mm or less.

When the spacing is less than 10 mm, since the density of the plasma (n _e ) is too high, there is a burden that the diameter of the injection hole 132 of the gas distribution plate 130 is too small to properly control the ion energy for the purpose of the present invention. This is because when the distance is wider than 100 mm, there is a high risk that active species generated in the generation region (I) are deposited on the upper surface of the gas distribution plate 130.

In the above, the method for calculating the diameter D of the injection hole 132 has been described. However, in the case of the gas distribution plate 130 having the injection slit 134, the value is equal to the width of the injection slit 134. Applicable

On the other hand, the susceptor 120 for placing the substrate 30 is usually grounded, but depending on the process, the second RF power source may be connected to the susceptor 120 in some cases.

If the spacing between the susceptor 120 and the gas distribution plate 130 is too wide, the density of the active species and ions is too low, the process efficiency is lowered, if too narrow may adversely affect the process uniformity, the susceptor 120 ) And the gas distribution plate 130 is preferably limited to 10mm or more and 30mm or less.

The gas distribution plate 120 is divided between the RF electrode 140 and the susceptor 120 into a generation area I and a reaction area II. The gas distribution plate 130 and the RF electrode 140 The gap and the gap between the gas distribution plate 130 and the susceptor 120 may be selectively adjusted according to the process conditions to increase the process efficiency.

To this end, a position adjusting means of the gas distribution plate 130 for moving the gas distribution plate 120 may be installed to adjust the distance between the gas distribution plate 120 and the RF electrode 140.

The position adjustment of the gas distribution plate 130 is made possible by allowing the gas distribution plate support member 131 to be moved up and down using a driving means not shown.

On the other hand, even if the distance between the gas distribution plate 120 and the RF electrode 140 is changed in this way, the raw material in the generation region (I) is reacted only through the injection hole 132 of the gas distribution plate 120 (II). Since it is preferable to inject into), it is preferable to properly install a sealing means such as an O-ring 131 so as not to leak the raw material through the periphery of the gas distribution plate 130.

In the above, the case of using the shower head type gas distribution plate 130 has been described, but as described above, when the thickness is 0.1 μm or more and less than 1 mm, the mesh type gas distribution plate 138 as shown in FIGS. 8 and 9 is described. Is preferably used.

The mesh-type gas distribution plate 138 has a structure in which a mesh-type mesh 138b is densely installed inside the rectangular or circular frame 138a.

The mesh-type gas distribution plate 138 may be manufactured by wet etching the aluminum or other conductive material, and may form a mesh pattern with an insulator material or fabric such as ceramic, Si, SiC, SiO _2, or the like. It may be.

The frame 138a is fixed to the inner wall of the chamber 110 and may be made of the same material as the mesh 138b or may be made of another material.

Like the shower head type gas distribution plate 130, the mesh type gas distribution plate 138 must be insulated from the RF electrode 140, so that the RF electrode 140 uses the insulating member 150 to form the chamber 110 and the mesh. It is insulated from the type gas distribution plate 138.

Like the shower head type gas distribution plate 130, the mesh type gas distribution plate 138 controls energy and density in the process of diffusing ions and electrons generated in the generation region (I) into the reaction region (II). Therefore, mesh spacing must be properly designed.

Accordingly, as shown in FIG. 10, when the maximum spacing of the mesh is D and the thickness of the sheath generated around the mesh 138b is S, it is preferable that the space between the meshes 138b is completely covered by the sheath in the PECVD apparatus. Therefore, it should be D≤2S.

Using the mesh-type gas distribution plate 138, the ions of the plasma generated in the generation region (I) are converted into neutral particles by trapping in the sheath or recombination due to the collision, and thus ion density and energy in the reaction region (II). It can be significantly lowered to prevent the thin film damage due to the ion impact.

In addition, as the plasma density decreases, the loss rate of active species due to recombination is also reduced, thereby increasing the thin film deposition rate.

An operation process of the PECVD apparatus among the plasma generating apparatuses 100 having such a configuration will be described below with reference to FIG. 2.

First, contaminants are removed through the exhaust port 180 by vacuum pumping, a process atmosphere is formed, and the substrate 30 is brought into the chamber 110 and placed in the upper part of the susceptor 120.

Subsequently, when the raw material is supplied to the generation region (I) between the RF electrode 140 and the gas distribution plate 130 through the gas inlet pipe 170 and the RF power source 160 is connected to the RF electrode 140, the plasma and Active species are produced.

The plasma and the active species thus generated are diffused from the generation region (I) to the reaction region (II) through the injection hole 132 of the gas distribution plate 130. Although diffused smoothly, ions in the plasma are trapped in the sheath near the injection hole 132 and collide with the surface or the neutral gas of the gas distribution plate 130 to be converted into neutral particles due to recombination or ion energy is lowered.

Therefore, the ion density and energy in the reaction region (II) are reduced to minimize the ion impact on the substrate 30, and only the neutral active species contributes to the deposition of the thin film, which is excellent in WER (Wet Etching Ratio) and RI. Can be obtained.

In addition, when forming a SiO ₂ thin film using SiH ₄ or Si ₂ H ₆ as a raw material or a Si ₃ N ₄ thin film using NH ₃ as a raw material, the hydrogen group (H +) generated by dissociating the raw material is a thin film. The proportion contained therein can be drastically reduced.

If the hydrogen group is excessively contained in the thin film, hydrogen is exploded in the high temperature process and causes a great damage to the thin film. Therefore, the content rate of the hydrogen group in the thin film should be strictly limited. The content of hydrogen groups can be reduced to a minimum.

In addition, it is possible to control the energy and density of ions in DLC (Diamond-Like Carbon) thin film deposition or CNT (Carbon Nano-Tube) manufacturing process, thereby obtaining excellent film quality.

If the second RF power source is connected to the susceptor 120 to be used as an etcher, as described above, the gas distribution plate 130 controls ion density and energy, thereby reducing the ion impact and reducing the porosity. The thin film can also be precisely etched. In particular, in the photolithography process using an ArF light source, it is possible to etch the lower film without damaging the photoresist as the upper film.

According to the plasma generating apparatus of the present invention, the density, ion energy, and electron energy of the plasma can be properly controlled to prevent thin film damage due to ion impact in the PECVD apparatus, thereby obtaining excellent film quality and active species due to recombination. The loss rate of the film is reduced, and thus the thin film deposition rate can be increased.

Claims (6)

A chamber having a reaction space therein for plasma formation; Substrate placing means located in the chamber; An RF electrode installed on the substrate mounting means; An RF power source connected to the RF electrode; A matcher for matching an impedance between the RF power supply and the RF electrode; A gas distribution means disposed between the RF electrode and the substrate placing means, the gas distribution means having a plurality of through portions insulated from the RF electrode and shielded by a plasma sheath; Gas inlet pipe for supplying gas to the space between the RF electrode and the gas distribution means Plasma generator comprising a The method of claim 1, The through portion of the gas distribution means is a plasma generating device, characterized in that the maximum diameter (D) is an injection hole of less than twice the plasma sheath thickness (S). The method of claim 2, The maximum diameter (D) of the penetrating portion is a plasma generating device of more than 1㎛ 11mm The method of claim 1, The through portion of the gas distribution means is a plasma generating device, characterized in that the injection slit having a width of less than twice the thickness of the plasma sheath (S). The method of claim 1, Plasma generator comprising a position adjusting means for adjusting the distance between the RF electrode and the gas distribution means The method of claim 5, The spacing between the RF electrode and the gas distribution means is 10mm to 100mm plasma generating apparatus

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