The present disclosure relates to a gas plug, an electrostatic attraction member, and a plasma etching device.
Typically, a substrate support assembly such as an electrostatic chuck that attracts and supports a semiconductor substrate is used inside a semiconductor manufacturing device such as a plasma treatment device.
For example, Patent Document 1 describes, as illustrated in
The gas plug of the present disclosure is composed of a columnar porous composite, the porous composite including a plurality of silicon compound phases which are connected to each other via a silicon phase including silicon as a main component.
The electrostatic attraction member of the present disclosure includes the gas plug mounted inside a ventilation hole that extends in a thickness direction.
The plasma treatment device of the present disclosure is provided with a treatment chamber and the electrostatic attraction member inside the treatment chamber.
A gas plug, an electrostatic attraction member, and a plasma treatment device according to the present disclosure will be described in detail below with reference to the drawings.
The plasma treatment device 10 illustrated in
In addition, a vacuum pump 9 is connected to the lower container 2, and a vacuum state can be formed inside the treatment chamber 3. In addition, a gas nozzle 7 that supplies an etching gas is provided in a peripheral wall of the lower container 2. A peripheral wall of the upper container 1 is provided with an induction coil 8 that is electrically connected to an RF power supply.
When the semiconductor substrate 6 is to be etched using the plasma treatment device 10, first, the treatment chamber 3 is exhausted to a predetermined vacuum degree by the vacuum pump 9. Next, after the semiconductor substrate 6 is attracted to the placement surface of the electrostatic chuck 5, etching gas such as CF4 gas, for example, is supplied through the gas nozzle 7, and electricity is supplied to the induction coil 8 from the RF power supply. Through this supply of electricity, a plasma of the etching gas is formed in the internal space above the semiconductor substrate 6, and the semiconductor substrate 6 can be etched in a predetermined pattern.
Here, examples of the etching gas include halogen-based gases, such as a fluorine-based gas that is a fluorine compound, such as CF4, SF6, CHF3, ClF3, NF3, C4F8, or HF, a chlorine-based gas that is a chlorine compound, such as Cl2, HCl, BCl3, or CCl4, or a bromine-based gas that is a bromine compound, such as Br2, HBr, or BBr3.
The insulating base 15 is a member for mounting an object to be treated, such as a semiconductor substrate 6. This insulating base 15 is made from a ceramic containing aluminum oxide, yttrium oxide, or aluminum nitride as a main component. An attraction electrode 17 made from a metal such as platinum, molybdenum, or tungsten is provided inside the insulating base 15. A lead wire 18 is connected to the attraction electrode 17, and the attraction electrode 17 is connected to a direct current power supply 19 through the lead wire 18.
The electrostatic chuck 5 has a ventilation hole 20 penetrating through the insulating base 15, the bonding layer 16, the heat transfer member 14, the equipment plate 13, the insulating plate 12, and the mounting plate 11 in the thickness direction, and is configured to cool the semiconductor substrate 6 by flowing helium gas into the ventilation hole 20 from the back surface side of the mounting plate 11.
The heat transfer member 14 is a member that allows heat generated inside the insulating base 15 to escape downward, and is made from aluminum (Al), copper (Cu), nickel (Ni), or alloys thereof.
The bonding layer 16 is a member for bonding the insulating base 15 and the heat transfer member 14, and is formed from, for example, a resin such as an epoxy resin, a fluorine resin, or a silicone resin. The thickness of the bonding layer 16 is, for example, from 0.1 mm to 2.0 mm.
An annular member 23 is made from a resin such as an epoxy, fluorine, or silicone resin, and is disposed on an end surface side of the bonding layer 16 to suppress degradation of the bonding layer 16 due to the etching gas.
The gas plugs 21 and 22 of the present disclosure are mounted inside the ventilation hole 20 (at both end portions in the example illustrated in
In addition, the gas plugs 21, 22 can suppress the formation of secondary plasma in the ventilation hole 20.
Also,
The gas plug 21 illustrated in
Note that the main component of the silicon compound phase 24 is, for example, silicon nitride (Si3N4), silicon carbide (SiC), silicon carbonitride (SiCxNy, where x and y are numerical values satisfying 4x+3y=4 in ranges of 0<x<1 and 0<y<4/3, respectively), silicon oxide (SiO2), or SiAlON (Si6-zAlzOzN8-z, where z is a numerical value satisfying 0.1≤z≤1), and these compositions may be stoichiometric or nonstoichiometric.
The content of the components constituting the silicon compound phase 24 may be determined using an energy dispersive X-ray spectrometer attached to a scanning electron microscope. Furthermore, the silicon compound can be identified using an X-ray diffractometer.
Here, the porous composite has pores 26, and the porosity measured using mercury porosimetry described below is 10 vol. % or greater.
In addition, the porous composite is formed with a three-dimensional mesh structure in which a plurality of silicon compound phases 24 are three-dimensionally arranged, and adjacent silicon compound phases 24 are bonded by a silicon phase 25 having silicon as a main component, and the silicon compound phase 24 may be surrounded by the silicon phase 25. In particular, the silicon compound phase 24 preferably contains silicon carbide as the main component.
When silicon carbide is the main component, the wettability of the silicon phase 25 is good, and therefore the bonding strength between the silicon compound phases 24 can be increased. In addition, since both silicon and silicon carbide have high thermal conductivity, the semiconductor substrate 6 can be efficiently cooled.
Moreover, the cross-sectional shape of the silicon compound phase 24 may be a polygonal shape. With such a configuration, particles generated by the supply of an etching gas can be more easily captured by the silicon compound phase 24 than when the cross-sectional shape is spherical.
Additionally, at least one surface of the silicon compound phase 24 may have a recessed portion 24a. With such a configuration, particles generated by the supply of etching gas can be more easily captured by the recessed portion 24a.
The content of silicon in the silicon phase 25 is 90 mass % or greater for each silicon phase 25, and the silicon phase 25 may include Al, Fe, Ca, and the like as unavoidable impurities. In particular, the content of silicon in the silicon phase 25 is preferably not less than 99 mass %, and the total content of unavoidable impurities is preferably not greater than 1 mass %.
In particular, the content of iron in the silicon phase 25 is preferably not greater than 0.4 mass %. When the iron content is within this range, the risk that iron forms particles and the particles float in the plasma treatment device is reduced.
The content of the components constituting the silicon phase 25 may be determined using an energy dispersive X-ray spectrometer attached to a scanning electron microscope.
Also, with the porous composite, the average pore diameter affects pressure loss, and when the average pore diameter is small, there is a concern that the pressure loss may increase. On the other hand, when the average pore diameter is large, the surface of the semiconductor substrate 6 is likely to have large recess-shaped depressions along the pores when the semiconductor substrate 6 has been attracted, and after etching, the flatness of the surface of the semiconductor substrate 6 may increase.
From this perspective, the average pore diameter of the porous composite is preferably from 30 μm to 100 μm.
When the average pore diameter of the porous composite is within this range, there is no increase in pressure loss, and the flatness of the surface of the semiconductor substrate 6 is not increased.
The average pore diameter of the porous composite can be determined by mercury porosimetry in accordance with JIS R 1655-2003.
Specifically, first, a cubic sample having a length of side from 6 to 7 mm is cut out from the porous composite. Next, mercury is pressed into the pores present in the sample using a mercury intrusion porosimeter, and the pressure applied to the mercury and the volume of mercury permeated into the pores are measured. This volume is equivalent to the volume of the pores, and the following equation (2) (Washburn equation) holds true for the pressure applied to the mercury and the pore diameter.
D=−4γ cos θ/p (2)
Where, D: Pore diameter (m)
p: Pressure applied to the mercury
γ: Surface tension of the mercury (0.48 N/m)
θ: Contact angle between the mercury and the pore wall surface)(140°
Each pore diameter D is determined from equation (2) for each pressure p, and the volume distribution and cumulative volume of the pores can be derived therefrom for each pore diameter D.
In addition, in the cumulative distribution curve showing a relationship between the pore diameter and the cumulative volume of the pores, the porous composite preferably has a ratio (p80/p20) of from 1.2 to 1.6, the ratio (p80/p20) being a cumulative 80 vol. % pore diameter (p80) to a cumulative 20 vol. % pore diameter (p20). When the ratio (p80/p20) is within this range, particles of various sizes included in the etching gas can be captured, and an increase in pressure loss can be suppressed, and therefore the risk of detachment from the electrostatic attraction member caused by an increase in pressure loss can be reduced.
When the area ratio of the non-connected part 27 in an observation range (2200 μm×1700 μm) in a cross-section of the porous composite is expressed by the following equation (1), the area ratio of the non-connected part 27 is preferably not greater than 3.5%.
(Area ratio of non-connected part 27)={(surface area of non-connected part 27)/(surface area of silicon phase 25+surface area of non-connected part 27)}×100(%) (1)
In order to determine the area ratio of the non-connected part 27, first, a portion of the porous composite is embedded in a polyester-based cold-embedding resin (for example, No. 105 available from Marumoto Struers K.K.) and formed into a cylindrical sample. An end surface of this sample is then polished using diamond abrasive grains (for example, FDCW-0.3 available from Fujimi Incorporated) to form a mirror surface. Subsequently, this mirror surface is photographed at a magnification from 5 to 50 using an industrial microscope (Eclipse LV150, available from Nikon Corporation), and the obtained images are stored in JPEG format.
Next, the image files stored in JPEG format are subjected to image processing using the software Adobe Photoshop Elements (trade name), and are stored in BMP format. Specifically, the chromatic colors in the images are deleted, and the images are converted to black and white duotone (black-and-white conversion) images. In this duotone conversion, a threshold value at which the silicon compound phase 24 and the silicon phase 25 can be identified is set while comparing images captured by the industrial microscope (Eclipse LV150, available from Nikon Corporation).
After the threshold value has been set, the surface area of the silicon phase 25 is read in pixel units using, for example, a free software called “Surface area from images” (creator: Teppei AKAO).
Then, the non-connected parts 27, which are gaps or air bubbles in the silicon phase 25, in the duo-tone converted image are colored with colors other than black and white through image processing, the surface area of the non-connected parts 27 is read in the same manner as described above, and if the surface area of the silicon phase 25 and the surface area of the non-connected parts 27 are substituted into equation (1), the area ratio of the non-connected parts 27 can be determined.
Additionally, the porosity of the porous composite may be from 20 vol. % to 40 vol. %.
When the porosity is within this range, pressure loss does not increase, and thermal conductivity and mechanical strength do not decrease. Porosity of the porous composite can be determined by the Archimedes method.
The thermal conductivity is, for example, 50 W/(m·K) or higher. The thermal conductivity may be determined in accordance with JIS R 1611:2010 (ISO 18755:2005).
The three-point bending strength, which indicates the mechanical strength, is, for example, 20 MPa or greater. The three-point bending strength may be measured in accordance with JIS R 1601:2008 (ISO 14704:2000).
The average diameter of the silicon compound phase 24 may be from 105 μm to 350 μm. The average diameter of the silicon compound phase 24 is measured by an intercept method using an image with a magnification from 20 to 800, obtained using, for example, a scanning electron microscope (hereinafter, a scanning electron microscope is referred to as an SEM), or can be determined by calculating through image analysis the equivalent circle diameters of a quantity of from 10 to 30 silicon compound phases 24 observed in a range from 0.2 to 2.0 mm×from 0.2 to 2.0 mm, for example, in an image obtained at a magnification of from 20 to 800 using an SEM, and calculating the average value of the equivalent circle diameters. When the intercept method is used, specifically, the average diameter is measured from a quantity of silicon compound phases 24 on a straight line of a certain length from several SEM images such that the quantity of silicon compound phases 24 is 10 or greater, and preferably 20 or greater.
A water-repellent resin having electrical conductivity may be adhered around a periphery of the silicon compound phases 24 and silicon phases 25. When the water-repellent resin having electrical conductivity is adhered, the electrostatic adherence of floating particles to the silicon compound phases 24 and the silicon phases 25 can be suppressed. Having electrical conductivity means that the surface resistance is 1012 S2 or less. Further, the surface resistance of the adhered water-repellent resin is preferably from 106 to 1012Ω.
The water-repellent resin is preferably a fluorine resin or a silicone resin. This is because these resins exhibit high water-repellency performance. In particular, the water-repellent resin is preferably a compound containing a fluorinated polysiloxane or a composition containing a silicone oligomer.
A lotus effect is obtained in which after washing with a water-soluble detergent, water droplets adhered to the surface of the water-repellent resin adsorb contamination, and therefore the efficiency of removing contamination adhered inside the porous composite can be increased.
The water-repellent resin may be identified using a Fourier transform infrared spectrometer (FTIR) or a gas chromatograph (GC mass). For example, if the water-repellent resin is a fluorine resin, the power spectrum can be measured by FTIR, and the water-repellent resin can be identified by comparing the standard power spectrum of the fluorine resin and the measured power spectrum. For a case in which GC mass is used, if polytetrafluoroethylene (PTFE), tetrafluoroethylene (TFE), hexafluoroethylene (HFE), or the like is detected as the thermally decomposed gas, the water-repellent resin can be identified as a fluorine resin.
Furthermore, the dense ceramic is preferably a ceramic having aluminum oxide or silicon carbide as the main component.
Note that the plasma treatment device 10 illustrated in
Next, an example of a method for manufacturing the gas plug of the present disclosure will be described.
First, from 5 to 30 parts by mass of a silicon powder having an average particle size from 1 to 90 μm is mixed with 100 parts by mass of an α-type silicon carbide powder having an average particle size from 90 to 250 μm, and then, as a molding aid, at least one of a thermosetting resin having a residual carbon ratio of 10% or greater after a subsequent degreasing treatment, such as, for example, a phenol resin, an epoxy resin, a furan resin, a phenoxy resin, a melamine resin, a urea resin, an aniline resin, an unsaturated polyester resin, a urethane resin, or a methacrylic resin, is added and wet mixed using a ball mill, a vibrating mill, a colloid mill, an attritor, a high-speed mixer, or the like. In particular, a resol or novolac type phenol resin is preferable as the molding aid from the perspective of low shrinkage after thermal curing.
Here, in order to obtain a gas plug in which the cross-sectional shape of the silicon compound phase is a polygonal shape, the α-type silicon carbide powder may be GC abrasive grains that are used as an abrasive.
In addition, in order to obtain a gas plug having a recessed portion in at least one surface of the silicon compound phase, GC abrasive grains having a recessed portion in the surface may be used.
In order to obtain a gas plug in which the ratio (p80/p20) of the pore diameters of the porous composite is from 1.2 to 1.6, an α-type silicon carbide powder having an average particle size from 110 to 230 μm may be used.
In order to obtain a gas plug in which the porosity of the porous composite is from 20 vol. % to 40 vol. %, and the average pore diameter is from 30 μm to 100 μm, the addition amount of the molding aid may be from 5 to 20 parts by mass per 100 parts by mass of the α-silicon carbide powder.
In addition, the silicon powder is formed into a silicon phase by a subsequent thermal treatment, and a silicon compound phase containing silicon carbide as the main component is connected thereto.
The purity of the silicon powder is preferably high, and a silicon powder having a purity of 95 mass % or higher is preferable, and a silicon powder having a purity of 99 mass % or higher is particularly preferable. Note that the shape of the silicon powder is not particularly limited and may be not only spherical or a shape close to spherical, but also an irregular shape.
The average particle size of the α-type silicon carbide powder and silicon powder can be measured by liquid phase precipitation, light dropping, laser scattering diffraction, or the like.
Next, granules are obtained by granulating a mixture of the α-type silicon carbide powder, the silicon powder, and the molding aid using various granulators such as a rolling granulator, a spray drier, a compression granulator, and an extrusion granulator.
The obtained granules are molded by a molding method such as dry compression molding or cold isotropic hydrostatic press molding to form a powder compact.
Next, a degreasing treatment is implemented at a temperature from 400 to 600° C. in a non-oxidizing atmosphere such as argon, helium, neon, nitrogen, or a vacuum. Subsequently, a porous composite in which a plurality of silicon compound phases containing silicon carbide as the main component are connected to each other via a silicon phase can be obtained by thermally treating at a temperature from 1400 to 1450° C. in a non-oxidizing atmosphere. Here, if a porous composite having a porosity from 20% to 40% and an average pore diameter from 30 μm to 100 μm is to be obtained, the thermal treatment is preferably implemented at a temperature from 1420 to 1440° C.
In order to reduce the temperature of the thermal treatment, the purity of the silicon may be set from 99.5 to 99.8 mass %.
The porous composite obtained by this manufacturing method can be subjected to machining such as grinding and polishing both end surfaces and the outer circumferential surface, and thereby the gas plug illustrated in
Furthermore, in order to obtain the gas plugs illustrated in
When a fluorine resin having electrical conductivity is to be adhered around the periphery of the silicon compound phases and the silicon phases, the gas plug is impregnated with a fluorine resin solution (a solution in which a fluorine resin having electrical conductivity is dissolved in a fluorine-based solvent), and then the gas plug is removed from this solution. The gas plug is then dried at ambient temperature, and then further heated for 1 hour to 2 hours at a temperature from 70° C. to 80° C., and thereby the fluorine resin having electrical conductivity can be adhered. When a silicone resin is to be adhered, the gas plug is impregnated with a silicone resin solution, after which the gas plug is removed from the solution. The gas plug is then dried at ambient temperature, and the silicone resin having electrical conductivity can be adhered.
Embodiments of the present disclosure were described above, but the present disclosure is not limited to the embodiments described above, and various modifications and enhancements can be made.
Number | Date | Country | Kind |
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2019-065773 | Mar 2019 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2020/013782 | 3/26/2020 | WO | 00 |