WO2017222201A1

WO2017222201A1 - Component made of tungsten carbide bulk for plasma device

Info

Publication number: WO2017222201A1
Application number: PCT/KR2017/005562
Authority: WO
Inventors: 황성식; 선호정; 이재범; 오준록; 김현정; 민경열; 김경인
Original assignee: 에스케이씨솔믹스 주식회사
Priority date: 2016-06-23
Filing date: 2017-05-29
Publication date: 2017-12-28

Abstract

Proposed are a component, made of tungsten carbide bulk, for use in a plasma device, the component exhibiting excellent plasma erosion resistance, securing a uniform distribution of plasma, improving electric and thermal conductivity, and having a simple structure, and a manufacturing method therefor. In the manufacturing method and the component for use in a plasma device that includes a chamber accounting for a reaction space for plasma treatment and a component positioned inside the chamber so as to be in contact with plasma, the component is made of tungsten carbide bulk having plasma erosion resistance and a volume resistivity of 10^-6-10³ Ωㆍcm.

Description

Components for plasma apparatus consisting of tungsten carbide bulk

The present invention relates to a plasma device component, and more particularly, to a plasma device component composed of a tungsten carbide bulk having high corrosion resistance to plasma.

The plasma processing apparatus arranges an upper electrode and a lower electrode in a chamber, mounts a substrate such as a semiconductor wafer or a glass substrate on the lower electrode, and applies electric power between both electrodes. Electrons accelerated by an electric field between the electrodes, electrons emitted from the electrodes, or heated electrons cause ionization collision with molecules of the processing gas, thereby generating a plasma of the processing gas. Active species such as radicals and ions in the plasma perform the desired microfabrication, for example etching, on the substrate surface. In recent years, design rules in the manufacture of microelectronic devices and the like have become increasingly finer, and in particular, plasma etch is required to have higher dimensional accuracy, and thus significantly higher power is used than in the prior art. The plasma processing apparatus includes components such as an edge ring, a focus ring, and a showerhead that are affected by plasma.

In the case of the edge ring, when the power is increased, the center part is maximized on the substrate and the edge part is the lowest on the substrate due to the wavelength effect in which standing waves are formed and the skin effect in which the electric field is concentrated at the center part of the electrode surface. Inhomogeneity deepens. If the plasma distribution is uneven on the substrate, the plasma processing becomes inconsistent and the quality of the microelectronic device is degraded. Korean Patent Publication No. 2009-0101129 seeks to achieve uniformity of plasma distribution by placing a dielectric between the susceptor and the edge portion. However, the patent has a problem in that the structure is complicated and precise design between the dielectric and the edge portion is difficult.

The problem to be solved by the present invention is to provide a plasma device component consisting of tungsten carbide bulk with excellent corrosion resistance to plasma and ensure uniformity of plasma distribution, improve electrical conductivity and thermal conductivity and simple structure.

Plasma device component consisting of a tungsten carbide bulk for solving the problems of the present invention is a chamber for forming a reaction space for plasma processing and the parts located in the chamber and in contact with the plasma, the component is plasma corrosion resistance Consisting of tungsten carbide bulk, the tungsten carbide having a volume resistivity of 10 ³ to 10 ⁻⁶ Ω · cm.

In the device of the present invention, the tungsten carbide bulk may be a compound based on tungsten and carbon. The tungsten carbide bulk may be single phase or multiple phases. The single phase may comprise a stoichiometric phase of tungsten and carbon and a nonstoichiometric phase outside of the stoichiometric composition. The single phase or complex phase may include a solid solution to which impurities are added.

In a preferred device of the invention, the component can be any one selected from an edge ring, a focus ring or a showerhead. The component is an edge ring that compresses the edge of the substrate placed in the susceptor, and the distribution of the plasma may extend beyond the edge of the substrate. The component preferably has a critical thickness of 0.3 mm. The part may be a sintered bulk. The part may be a physical or chemical vapor deposited bulk.

According to the plasma device component made of the tungsten carbide bulk of the present invention, by using a component including tungsten carbide which is excellent in plasma corrosion resistance and imparted with electrical conductivity, excellent corrosion resistance to plasma and uniformity of plasma distribution are ensured. The structure is simple.

1 is a view schematically showing a plasma processing apparatus equipped with a plasma component according to the present invention.

2 is another diagram schematically showing a plasma processing apparatus equipped with a plasma component according to the present invention.

3 is an electron micrograph (a) of a WC according to the present invention, a photograph (b) of WC: Si = 95: 5 (vol%), and a photograph (c) of WC: C = 97: 2 (vol%). .

4 is an XRD graph of the WC according to the present invention.

5 is a graph comparing the etching rate (%) of the WC and the conventional SiC according to the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments described below may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

The embodiment of the present invention provides a plasma device component (hereinafter, referred to as a plasma component) that has excellent corrosion resistance to plasma, secures uniformity of plasma distribution, and has a simple structure by using tungsten carbide bulk. Such a plasma processing apparatus includes components such as an edge ring, a focus ring, and a showerhead that are affected by plasma, and here, the edge ring will be described as an example. To this end, a plasma component will be described in detail with respect to the edge ring of the present invention, and a method of manufacturing the plasma component will be described in detail.

Bulk in the embodiment of the present invention refers to the form of the plasma component itself without the intervention of the base material. In case of involvement of the base material, the tungsten carbide is coated or bonded to the base material. In other words, the bulk of the present invention excludes coating or bonding tungsten carbide to the base material. The reason for applying the bulk is to use the properties of the bulk only by excluding the influence of the base material in terms of corrosion resistance.

1 and 2 are diagrams schematically showing a plasma processing apparatus equipped with a plasma component according to an embodiment of the present invention. In addition to the structure of the apparatus presented within the scope of the present invention, it can be applied to the plasma processing apparatus of various structures.

1 and 2, the treatment apparatus of the present invention includes a chamber 10, a susceptor 20, a showerhead 30, and an edge ring 40. Here, the susceptor 20, the shower head 30, the edge ring 40, and the like are plasma components AP affected by the plasma. The chamber 10 defines a reaction space, and the susceptor 20 mounts the substrate 50 on the upper surface and moves up and down. In some cases, the susceptor 20 may be fixed and not move. Here, the vertical motion is taken as an example. The shower head 30 is positioned above the susceptor 20 and sprays a process gas onto the substrate 50. The shower head 30 has a gas supply pipe 12 connected through the chamber 10 to introduce the process gas from the outside. The shower head 30 includes a buffer space 31 for uniformly dispersing the inside of the shower head 30 before the process gas introduced through the gas supply pipe 12 is injected, and a nozzle part 32 composed of numerous through holes. It includes. The edge ring 40 is installed on the inner wall of the chamber 10 and is located on the ring support 41.

Outside the chamber 10, an RF power source 16 for supplying RF power for generating plasma is connected to a plasma electrode or an antenna. The connection scheme is various, and as shown, the plasma electrode is integrally formed with the shower head 30, and the RF power source 16 is provided to the gas supply pipe 12 so that the RF power is applied to the center of the electrode. ) Can be connected. In order to control energy of the plasma incident on the substrate 50, a separate RF power source may also be applied to the susceptor 20. Although not shown, the susceptor 20 may include a heater for preheating or heating the substrate 50, a lift pin for mounting the substrate 50, and the like.

When the substrate 50 is placed in the susceptor 20, the susceptor 20 is raised to the position of the plasma processing step. The edge ring 40 rises together while pressing the edges of the substrate 50. When the susceptor 20 is raised to place the substrate 50 in the process position, the process gas is injected through the shower head 30, and then RF power is applied to convert the process gas into plasma active species having strong reactivity. . The active paper may be deposited or etched on the substrate 50, and the process gas may be discharged at a constant flow rate through the exhaust port 14 during the process. After the treatment process is performed for a predetermined time, residual gas is discharged to the exhaust port 14. Subsequently, the susceptor 20 is lowered and the substrate 50 is carried out from the chamber 10 to the outside.

Tungsten carbide according to an embodiment of the present invention includes WC and W ₂ C. In addition to the above WC and W ₂ C, the tungsten carbide of the present invention may include other tungsten carbide compounds within the scope of the present invention. That is, tungsten carbide refers to all compounds based on tungsten and carbon. The tungsten carbide of the present invention may be either a single phase or a composite phase. Here, the tungsten carbide single phase includes both the stoichiometric phase of tungsten and carbon and the nonstoichiometric phase deviating from the stoichiometric composition, and the composite phase is, for example, based on the tungsten and carbon At least two of the tungsten carbide compounds referred to as ()) are mixed at a predetermined ratio. In addition, the tungsten carbide of the present invention includes all impurities such as impurities added to the single phase or composite phase of the tungsten carbide to form a solid solution or inevitably added in the process of manufacturing tungsten carbide.

Hereinafter, the influence of the plasma around the edge ring 40 in the plasma component AP will be described. When the power to form the plasma is high, the center of the substrate 50 is maximized and the edge is generally the lowest due to the wavelength effect in which standing waves are formed in the chamber 10 or the skin effect in which the electric field is concentrated at the center of the electrode surface. The plasma distribution on the substrate 50 becomes nonuniform. If the plasma distribution is uneven on the substrate 50, the plasma processing becomes inconsistent and the quality of the microelectronic device is degraded. Here, the plasma distribution refers to a state in which a plasma is applied on the substrate 50 and the tungsten carbide edge ring 40, and the distribution indicates a plasma density at each point of the substrate 50 and the tungsten carbide edge ring 40. It is associated with the straightness towards the substrate 50.

Near the edge of the substrate 50 (ED), the difference in volume resistivity with the tungsten carbide edge ring 40 has a great effect on the plasma distribution uniformity. Here, the uniformity refers to the degree of change in the plasma distribution. When the uniformity is small, the plasma distribution changes abruptly, and when the uniformity is large, the plasma distribution changes slowly. For this purpose, the volume resistivity of the tungsten carbide edge ring 40 is preferably similar or lower than the volume resistivity of the substrate 50. In this case, since the plasma distribution extends beyond the edge of the substrate 50 to the tungsten carbide edge ring 40, the edge of the substrate 50 has a relatively high uniformity. The uniformity means that the plasma density and the straightness toward the substrate 50 are excellent. In the drawing, the state that deviates from the edge of the substrate 50 is expressed as near edge ED.

The volume resistivity of the tungsten carbide edge ring 40 according to the embodiment of the present invention is similar to or smaller than the substrate 50 can be described in the following aspects. If the volume resistivity of the tungsten carbide edge ring 40 is similar or smaller than the substrate 50, the plasma distribution extends beyond the edge of the substrate 50 to the tungsten carbide edge ring 40. Accordingly, the volume resistivity of the tungsten carbide edge ring 40 of the present invention extends from the edge of the substrate to the tungsten carbide edge ring 40 so that the plasma distribution over the entire substrate 50 is uniform even at the edge of the substrate 50. It can be said that. Such volume resistivity may be defined as extending the plasma distribution beyond the edge of the substrate 50 and extending the tungsten carbide edge ring 40.

Volume resistivity of 10 ³ to 10 tungsten carbide edge ring 40 of the present invention ^- ⁶ Ω cm and is based on the technical idea for making uniform the plasma distribution in the edge of the substrate 50. Accordingly, the volume resistivity cannot be obtained through simple repeated experiments without considering the technical idea. In the above, the relationship between the volume resistivity of the tungsten carbide edge ring 40 and the substrate 50 has been described taking the edge ring as an example. However, in the case of other parts such as showerheads, the viewpoint that the volume resistivity of tungsten carbide improves the plasma corrosion resistance is the same.

On the other hand, plasma corrosion resistance is affected by the density (g / cm 3) of the part. In other words, as the density of the plasma component increases, the plasma corrosion resistance increases. The density of the tungsten carbide (WC) of the invention is 3.95 (g / ㎤) of 3.12 (g / ㎤) and alumina (Al ₂ O ₃₎ of the silicon carbide (SiC) is used as the 15.63 (g / ㎤), typically It is significantly larger than its bulk. Accordingly, the tungsten carbide bulk of the present invention has a higher corrosion resistance to plasma than conventional silicon carbide and alumina.

The plasma component AP including the edge ring 40 according to the embodiment of the present invention has a critical thickness. The reason is at least as follows. First, when the edge ring 40 is initially mounted on the etching equipment, the surface of the edge ring 40 is in line with the surface of the substrate 50. The substrate 50 is replaced for each subsequent etching process but the edge ring 40 remains the same. As the etching process is repeated, a step occurs between the surface of the substrate 50 and the surface of the edge ring 40 and the step continuously increases.

Second, as the pattern of the device becomes finer, the aspect ratio of the etching pattern continues to increase, and recently, it has almost reached its limit. For etching corresponding to this aspect ratio, the plasma power must be increased. In plasma etching, chemical etching by chemical reaction and physical etching by physical ion collision are mixed. However, as the plasma power increases, the strength of the physical etching becomes relatively larger than the chemical etching and becomes overwhelming at a predetermined power or more. Therefore, it becomes more difficult to maintain the corrosion resistance of the edge ring 40.

Third, when the level difference between the surface of the substrate 50 and the surface of the edge ring 40 extends beyond the predetermined thickness, the direction of active ions rushing to the edge of the substrate 50 is from the direction perpendicular to the surface of the substrate 50. Gradually the direction becomes oblique. By the diagonal etching ions, an etching pattern such as an etching hole or a trench is formed in the diagonal direction on the substrate 50. In the diagonal direction, misalignment occurs from the pattern of the underlying layer of the etching layer, thereby reducing the yield of the device. Therefore, the maximum etching thickness and the maximum number of substrates 50 that are the allowable misalignment should be etched to set the minimum etching thickness limit for maintaining the productivity of the equipment.

Considering the reasons mentioned above, the thickness for general corrosion resistance should be more than 0.3mm. This thickness is called the critical thickness. Of course, the plasma thickness of the tungsten carbide bulk is typically applied within a thickness of 3mm, but may be applied to more than the thickness if necessary. This is because the thickness of the plasma component AP requires a critical thickness which is the minimum thickness for corrosion resistance. The critical thickness is designed in consideration of the technical idea of the present invention, which cannot be obtained by repeated experiments of the plasma component (AP).

Hereinafter, a method of manufacturing a bulk plasma component AP including tungsten carbide (WC) will be described. Tungsten carbide plasma components (AP) are manufactured by sintering and deposition, such as physical or chemical vapor deposition, and are themselves bulk components. In addition, physical or chemical vapor deposition is the production of tungsten carbide plasma component (AP) using a source material, can be distinguished from other methods (eg, sintering). The methods presented herein are merely presenting the appropriate examples for each, and therefore include other methods within the scope of the present invention.

The sintering is sintered tungsten carbide powder in an atmosphere of a lower oxygen than atmospheric pressure or reducing gas atmosphere, such as vacuum or inert gas atmosphere. The inert gas may be any known inert gas, and preferably argon, nitrogen, and the like. The reducing gas may be any known reducing gas, and preferably hydrogen, ammonia, carbon monoxide, carbon dioxide, and the like. The tungsten carbide plasma component produced by sintering in this way is a sintered body in bulk form.

Tungsten Carbide Plasma Parts by Physical or Chemical Vapor Deposition

In the chemical vapor deposition, the tungsten source and the carbon source are reacted to be deposited on the base material under certain conditions, grown, and subsequently removed. For example, WF ₆ is used as the tungsten precursor and CH ₄ is used as the carbon precursor, and the deposition temperature can be deposited by a chemical vapor deposition apparatus at 500 to 1500 ° C. Physical vapor deposition sputters a tungsten target with an inert gas such as Ar and injects a gas such as CH ₄ containing carbon to allow tungsten carbide to be synthesized and grown on top of the base material, or the target itself is tungsten. After sputtering with carbides to allow tungsten carbide to grow on top of the base material, the base material is removed. The tungsten carbide component manufactured by physical or chemical vapor deposition is in the form of a bulk as described above.

Hereinafter, in order to explain in detail the physical properties of the plasma component of the present invention, the following examples are presented. However, the present invention is not particularly limited to the following examples. The electrical conductivity (Ω · cm) of the components shown in Examples and Comparative Examples was measured by model name LORESTA-GP MCP-T610 (manufacturer, Mitsubish), and thermal conductivity ((W / m · k) was model name LFA 467-TMA 402 F3) (Manufacturer, NETZSCH).

Electrical conductivity (Ω · cm) and thermal conductivity of WC, WC: Si = 95: 5 (vol%), WC: C = 97: 0.2 (vol%), and W ₂ C manufactured by sintering method ((W) /m.k) was measured by the apparatus presented above, where WC: Si = 95: 5 (vol%) and WC: C = 98: 0.2 (vol%) were Si and C in vol%. 5% and 0.2% are employed, Figure 3 shows electron micrographs (a) of WC, photographs (b) of WC: Si = 95: 5 (vol%) and WC: C = 97: 0.2 (vol %) Picture (c), and FIG. 4 is an XRD graph of WC.

The electrical conductivity (Ω · cm) and thermal conductivity ((W / m · k) of the silicon carbide and alumina produced by the sintering method were measured by the above-described apparatus, wherein the silicon carbide was doped by the doping. Cm), and is commonly used for plasma components.

Table 1 shows the electrical conductivity (Ω · cm) and the thermal conductivity ((W / m · k) of Examples 1 to 4 and Comparative Examples 1 and 2 of the present invention, wherein the electrical conductivity (Ω · cm) and the thermal conductivity are as follows. (W / m · k) is an average value obtained by a plurality of measurements, not one, and is represented by a power of 10 for convenience.

구분division	조성물Composition	전기전도도(Ωㆍ㎝)Electrical Conductivity (Ω · cm)	열전도율(W/mㆍk)Thermal Conductivity (W / m · k)
실시예1Example 1	WC WC	10^-6 10 ^-6	179179
실시예2Example 2	WC:Si=95:5(vol%)WC: Si = 95: 5 (vol%)	10^-5 10 ^-5	160160
실시예3Example 3	WC:C=97:0.2(vol%)WC: C = 97: 0.2 (vol%)	10^-5 10 ^-5	160160
실시예4Example 4	W₂CW ₂ C	10^-5 10 ^-5	185185
비교예1Comparative Example 1	SiC SiC	10³~10^-2 10 ³ to 10 ^-2	150150
비교예2Comparative Example 2	Al₂O₃ Al ₂ O ₃	10¹⁴ 10 ¹⁴	3333

According to Table 1, the electrical conductivity of the embodiment of the present invention WC is 10 ^-6 , WC: Si = 95: 5 (vol%), WC: C = 97: 0.2 (vol%) and W ₂ C are each 10 Was ^-5 . The electrical conductivity of SiC as a comparative example was 10 ³ to 10 ^-2 , and Al ₂ O ₃ was 10 was ¹⁴ . On the other hand, to use a plasma component, the electrical conductivity is less than 10 ⁰ units are preferred. WC, WC: Si = 95: 5 (vol%), WC: C = 97: 0.2 (vol%) and W ₂ C of the present invention is 10 ^-5 ~ 10 ^-6, so the electrical conductivity is preferable in terms of electrical conductivity Composition. By the way, Al ₂ O ₃ Since it is 10 ¹⁴ , it cannot be used as a plasma component.

The thermal conductivity of WC, WC: Si = 95: 5 (vol%), WC: C = 97: 0.2 (vol%), and W ₂ C, which are examples of the present invention, was 179, 160, 160, and 185, respectively. In contrast, Comparative Examples SiC and Al ₂ O ₃ were 150 and 33, respectively. Thermal conductivity is an index that emits heat generated by collision with ions during plasma treatment to the outside. If the thermal conductivity is small, heat transfer does not occur properly, which causes a thermal shock to the plasma component, which reduces the lifetime of the component, and in the case of a component adjacent to the substrate such as an edge ring, heats the edge of the substrate, thereby increasing the etching rate locally. Adversely affects yield. WC, WC: Si = 95: 5 (vol%), WC: C = 97: 0.2 (vol%), and W ₂ C have better thermal conductivity than SiC, increasing component life and improving device yield. In the case of Al ₂ O ₃ , the thermal conductivity was too low to be suitable for plasma components.

5 is a graph comparing the etching rate (%) of the WC and the conventional SiC according to the embodiment of the present invention. In this case, the etching rate (%) was measured after etching with CF ₄ gas plasma. In addition, the etching rate (%) represents a change in weight.

Referring to FIG. 5, when the conventional SiC etching rate is 100%, the WC of the present invention was 82%. That is, the etching rate of the WC of the present invention is reduced by about 18% compared to the conventional SiC. In other words, the WC of the present invention exhibited excellent corrosion resistance to plasma compared to conventional SiC. In addition, the difference in etching rate is remarkable as the plasma power increases. Plasma corrosion resistance is affected by the density of the part (g / cm 3). In other words, as the density of the plasma component increases, the plasma corrosion resistance increases. Since the density of WC of this invention is 15.63 (g / cm <3>) and SiC is 3.12 (g / cm <3>), it was confirmed that the corrosion resistance improved with the density of a component.

As mentioned above, although the present invention has been described in detail with reference to preferred embodiments, the present invention is not limited to the above embodiments, and various modifications may be made by those skilled in the art within the scope of the technical idea of the present invention. It is possible.

* Description of the sign

10; Chamber 12; Gas supply pipe

20; Susceptor 30; Shower head

40; Edge ring 41; Ring support

50; Substrate AP; Plasma components

Claims

A chamber forming a reaction space for plasma treatment: and

A component located inside the chamber and in contact with the plasma;

The parts are made of a tungsten carbide in the bulk plasma corrosion resistance, wherein the tungsten carbide has a volume resistivity of 10 3 to 10 - parts for a plasma device, consisting of tungsten carbide bulk, characterized in that Ω and having a 6 cm.
2. The plasma device component of claim 1, wherein the tungsten carbide bulk is a tungsten and carbon based compound.
The plasma device component of claim 1, wherein the tungsten carbide bulk is a single phase or a complex phase.
4. The plasma device component of claim 3, wherein the single phase comprises a stoichiometric phase of tungsten and carbon and a nonstoichiometric phase outside of the stoichiometric composition.
4. The plasma device component of claim 3, wherein the single phase or composite phase comprises a solid solution in which impurities are added to the single phase or composite phase.
The plasma device component of claim 1, wherein the component is any one selected from an edge ring, a focus ring, and a showerhead.
The plasma device component of claim 1, wherein the component is an edge ring that compresses an edge of a substrate placed in a susceptor, and the distribution of the plasma extends beyond the edge of the substrate. .
The plasma device component of claim 1, wherein the component has a critical thickness of 0.3 mm.
The component of claim 1, wherein the component is a sintered bulk.
The plasma device component of claim 1, wherein the component is a physical or chemical vapor deposition bulk.