Glass ring made from multi-component glass, and method and apparatus for manufacturing said glass ring.

Abstract

This invention provides a method, apparatus, and virtually defect-free thick-walled rings that can be manufactured from multi-component glass to produce near-net geometry rings, even in the case of thick-walled rings with wall thicknesses exceeding 10 mm. [Solution] First, a ring-shaped blank is manufactured from multi-component glass using a casting process. In the casting process, a casting strand made of molten multi-component glass is fed into a casting mold with a ring-shaped casting cavity 1a extending around a central axis 1s. The casting strand, upon impact with the collision zone 5, branches into a right substream 7a and a left substream 7b. The substreams 7a and 7b converge in a confluence zone 6 within the casting cavity 1a, filling the casting cavity 1a to at least a portion of its height. After the molten glass cools, a ring-shaped blank is obtained, which is further processed into a glass ring made of multi-component glass.

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing glass rings from multi-component glass, and more particularly to a method for manufacturing large, preferably thick-walled, glass rings.

[0002] Furthermore, the present invention relates to an apparatus for manufacturing glass rings from multi-component glass.

[0003] The present invention also relates to a glass ring made of multi-component glass.

[0004] Such glass rings are used, for example, in semiconductor manufacturing as so-called "plasma etching rings" to hold semiconductor wafers in a plasma etching system.

[0005] Plasma-assisted manufacturing processes, such as plasma-assisted dry etching (also abbreviated as "plasma etching"), are technologies used for manufacturing ultrafine structures of semiconductor components, high-resolution displays, and solar cells. Plasma etching is performed in a plasma chamber where a reactive etching plasma is generated while the chamber is flushed with a low-pressure etching gas. For etching silicon-based structures, halogen-containing etching gases such as CF4, C2F6, C3F8, C4F6, CH2F2, C4F8, NF3, SF6, HF, HCl, or HBr are commonly used. The components of the plasma chamber are cleaned from time to time, and this cleaning is usually performed using plasma and fluorine-containing etching gases. [Background technology]

[0006] Rings exposed to plasma and etching gases are often made of quartz glass and are also called etching rings. For their manufacture, according to European Patent Application Publication No. 3 656 746, an intermediate product in the form of a synthetically produced hollow cylindrical quartz glass is manufactured, and the etching rings are cut from this intermediate product.

[0007] Synthetically produced quartz glass is characterized by its high purity, UV transmittance, chemical resistance to many substances used in the manufacturing process, and high-temperature resistance. However, quartz glass is eroded by plasma in the presence of halogen-containing, and especially fluorine-containing, etching gases, resulting in increased surface roughness and increased particle formation during the manufacturing process.

[0008] Multicomponent glasses containing multiple additional components, particularly rare earth metal compounds, in addition to SiO2 are known to have increased dry etching resistance. For example, U.S. Patent No. 6,887,576 proposes increasing the dry etching resistance of quartz glass by doping it with elements that can react with fluorine to form fluoride compounds whose boiling point is higher than that of SiF4. Examples of these elements are Al, Sm, Eu, Yb, Pm, Pr, Nd, Ce, Tb, Gd, Ba, Mg, Y, Tm, Dy, Ho, Er, Cd, Co, Cr, Cs, Zr, In, Cu, Fe, Bi, Ga, and Ti.

[0009] U.S. Patent Application Publication No. 2014 / 0274653 discloses multi-component glass containing rare earth oxides and yttrium oxide, characterized by higher erosion resistance to plasma erosion compared to quartz glass. The chemical composition of these plasma-resistant multi-component glasses is specified as follows: Yttrium oxide (Y2O3): 5% to 40% by weight Aluminum oxide (Al2O3) 5% to 30% by weight Silicon dioxide (SiO2): 10% to 80% by weight Magnesium oxide (MgO) 1% to 20% by weight. [Overview of the project] [Problems that the invention aims to solve]

[0010] Multicomponent glass is typically manufactured by melting powdered raw materials and, therefore, for manufacturing-related reasons, is of lower purity than glass that can be manufactured "synthetically," for example, by precipitating glass-forming components from the gas phase. In particular, depending on the purity of the raw materials used, multicomponent glass may contain impurities that are harmful in semiconductor manufacturing.

[0011] Plasma-resistant multi-component glasses containing rare earth oxides, as well as other technically specialized glasses, often exhibit a significant tendency towards crystallization. However, during the plasma dry etching process, crystals, pores, and other heterogeneities within the glass lead to particle formation. To avoid crystallization, for example, when manufacturing components from the plasma-resistant multi-component glass described in U.S. Patent Application Publication No. 2014 / 0274653, it is proposed to melt a mixture of starting components and then quench this molten material, or to first melt the multi-component glass, grind it into a powder, and then sinter the powder at a temperature below the glass's melting point.

[0012] However, because glass generally has low thermal conductivity, rapid cooling from high temperatures without crystallization is only possible with small wall thicknesses. Thus, it is virtually impossible to manufacture thick-walled rings with wall thicknesses of 10 mm or more. If glass powder is sintered at temperatures below its melting point, residual pores remain in the sintered body, preventing the acquisition of transparent, non-porous multi-component glass. Furthermore, due to the high specific surface area of ​​the glass powder, crystallization at high temperatures has a particularly significant impact.

[0013] The present invention is particularly aimed at identifying a method for manufacturing near-net geometry rings from multi-component glass, even in the case of thick-walled rings with wall thicknesses exceeding 10 mm.

[0014] Alternatively or additionally, the present invention aims to provide a casting method for glass rings that enables a sufficiently high cooling rate with the lowest possible associated crystal formation, and in the best case, prevents crystal formation, even in the case of thick-walled glass rings with a wall thickness exceeding 10 mm.

[0015] Furthermore, the present invention is based on the objective of providing an apparatus for carrying out this method.

[0016] Furthermore, an objective of the present invention is to provide a thick-walled ring made of multi-component glass that is virtually free of defects such as bubbles, inclusions, and crystals. [Modes for carrying out the invention]

[0017] With respect to the method, this objective is achieved by a method having the features of claim 1.

[0018] The method is used to manufacture glass rings from rare earth oxide-containing multi-component glass by casting the molten multi-component glass in a casting mold.

[0019] In a melting unit, such as a glass melting tank or crucible, a glass molten product is produced from multi-component glass. Here, crystallizing glass, such as the multi-component glass in question, must be heated to a sufficiently high melting temperature to obtain a homogeneous molten product, to melt the crystals, and / or to avoid nucleation in the glass molten product. A high melting temperature typically results in a low-viscosity glass molten product, which essentially makes its processing in the casting process more difficult. This is because, especially when casting low-viscosity glass, forced convection, wrinkling, and mixing of glass molten products at different temperatures occur easily, thereby promoting the formation of streaks. Streaks are material changes in the material that result in a visible difference in the refractive index of the glass.

[0020] When processing multi-component glass by casting, the molten glass is preferably composed of 10 1 dPa·s~10 4 It has a viscosity in the range of dPa·s.

[0021] One or more casting strands are produced simultaneously from this low-viscosity glass molten material.

[0022] Due to gravity, freely flowing glass strands typically have a direction perpendicular to their longitudinal axis and, in the simplest and most preferred case, reach directly into a collision zone located within the casting cavity or having a fluid connection to the casting cavity. Alternatively, the casting strand can be supplied to the collision zone in a different orientation of the strand's longitudinal axis by a deflecting element such as a feed trough or a feed pipe.

[0023] Particularly, in order to quickly fill the casting cavity while minimizing the formation of streaks and crystallization, the casting strand is split into a right sub-stream and a left sub-stream after flowing out of the collision zone.

[0024] This splitting halves the flow path required to close the ring or fill the casting cavity. This also means that the flow time is halved or at least reduced. This contributes to the two sub-streams having approximately the same thermal history and surface temperature, especially when the two sub-streams merge in a confluence zone.

[0025] In the simplest and most preferred case, the splitting of the casting strand into two sub-streams occurs within the casting cavity. The casting strand hits the inner wall of the casting cavity and is divided into left and right sub-streams. The sub-streams flow around the inner wall of the casting cavity, cool down, and merge again in a confluence zone. In the area where the sub-streams converge, characteristic process-related streaks are formed, which are also referred to hereinafter as "casting streaks". These casting streaks can function as positioning markers. This is useful, for example, in applications where a specific circumferential position of a glass ring must be maintained, or in systems where the same glass ring must be reinstalled at the same location with the same positioning after removal.

[0026] Low-viscosity multi-component glass cools and solidifies rapidly upon contact with the walls of the casting cavity. This also applies to the side walls of the casting cavity, particularly the floor of the casting cavity. Preferably, the supply of the glass molten material and any inclination of the casting cavity floor are adjusted so that two substreams fill the casting cavity as completely as possible, and both substreams cover the casting cavity floor and contact the side walls of the casting cavity. The casting cavity is optionally filled by the molten front, which preferably extends across the entire width of the casting cavity and moves continuously at a nearly constant speed across the already solidified molten material, similar to an avalanche. The insulating effect of the already solidified multi-component glass contributes to maintaining the high temperature and low viscosity of the glass molten material, thereby allowing the molten front to continue moving further toward the confluence zone despite the same initial viscosity. When the casting cavity floor is completely covered with solidified glass molten material, this can lead to an acceleration of the movement speed of the molten front. To adjust the speed of movement of the molten material at the front of the casting cavity, the inclination of the casting cavity floor relative to the horizontal can be changed during the casting process.

[0027] The collision zone, the confluence zone, and the central axis of the casting mold are preferably on a single line.

[0028] In particular, it has been found that it is advantageous for low-streak formation and crystallization if the collision zone is located at the upper height level E1 and the confluence zone is located at the lower height level E2.

[0029] During the casting process, the casting cavity floor of the casting mold is tilted at least temporarily relative to the horizontal so that the molten glass can flow from the impact point at the upper height level E1 within the casting cavity to the confluence zone at the lower height level E2. Starting from the impact zone at the upper height level E1, the casting strand gradually fills the casting cavity. The tilt can facilitate the filling of the casting cavity by the molten glass.

[0030] After the molten glass has cooled, a ring-shaped blank made of multi-component glass can be removed from the casting mold. From this, the glass ring can be obtained to its final product dimensions through further processing. Further processing may include, for example, heat treatment to relieve mechanical stress, and / or mechanical processing by cutting, grinding, or polishing.

[0031] The collision zone is located at an upper height level E1, which is higher than the lower height level E2 where the confluence zone is located, thereby creating an angle of inclination with respect to the horizontal, for example, in the range of 1° to 30°, between these two zones at height levels E1 and E2. This allows the molten glass in the casting cavity to flow downward from the collision zone to the confluence zone. The collision zone may be fluidly connected to the casting cavity and may be located, for example, within the casting cavity. It is particularly preferable that the confluence zone be located within the casting cavity.

[0032] In this regard, it has been found to be advantageous if the casting mold is oriented such that the casting cavity floor has an inclination relative to the horizontal between height levels E1 and E2, and the inclination is changed during the casting process.

[0033] The height difference between height levels E1 and E2 may be caused by the orientation of the entire casting mold in a space inclined with respect to the horizontal, and / or by the structural design of the casting cavity floor with a downward-sloping ramp or multiple downward-sloping ramps. The height difference may remain constant during the casting process, but it is preferable that it be changed during the casting process. In a variation of the preferred method, a higher inclination angle is set at the start of the casting process and is reduced at least temporarily during the casting process.

[0034] In the simplest example, the casting cavity floor has a flat cross-section between the casting cavity sidewalls. In an alternative method, a casting cavity floor with a U-shaped or V-shaped cross-section is provided between the casting cavity sidewalls over at least a portion of its cross-section to guide two branching substreams at its center. This delays the point at which the molten glass comes into contact with the inner or outer wall of the casting cavity. In this embodiment as well, the casting mold preferably has an inclination with respect to the horizontal between height levels E1, E2, and this inclination can be changed during the casting process.

[0035] The temporal change in the tilt of the entire casting mold relative to the horizontal is preferably controlled or regulated by a mechanism. The tilt is preferably reduced during the casting process.

[0036] The tilt of the casting mold is preferably controlled so as to prevent the accumulation of glass lumps, particularly in the collision zone area, and to achieve unimpeded merging of glass strands in the merging zone area. For this purpose, tilts in the angular range of 1 to 30 degrees have been found to be advantageous. A permanent tilt may result in uneven height of the glass ring, such that the formed glass ring is higher in the merging zone area than in the collision zone area. However, in some cases, the generally undesirable height difference can be equalized by gradually reducing the tilt until it reaches a horizontal position before the end of the casting process.

[0037] The change in the tilt of the casting mold is usually stopped when it reaches the horizontal direction of the casting cavity floor. Preferably, the rate at which the tilt of the casting mold is changed is constant. However, the rate may be variable. In particular, the rate may be higher at the beginning of the casting process than at the end. Preferably, the tilt of the casting mold is changed only after the two substreams have first merged.

[0038] The variable inclination of the casting mold, particularly the casting cavity floor, facilitates the smooth merging of glass strands in the merging zone.

[0039] In this regard, it has been found to be advantageous if the position of the impact zone is variable during the first casting stage. Initially, it is preferable that the impact zone be located on a ramp that slopes downward from the outside to the inside toward the inner wall of the casting cavity. During the second casting stage, the position of the impact zone on the ramp is changed, preferably shifted outward from the inner wall of the casting cavity.

[0040] The ramp may extend along a partial length of the outer circumference of the casting cavity. For example, the ramp may be wedge-shaped when viewed from above, and the wedge-shaped surface may be straight, linear, or curvilinear across the direction of the inclination. The ramp may be considered part of the casting cavity or the casting cavity floor. The ramp provides a higher inclination in the area of ​​the impact zone. This means that the incoming glass molten is deflected at an angle greater than the inclination angle of the rest of the casting cavity floor but less than 90°, thereby supporting the flow of glass molten away from the impact zone. The inclination of the ramp can be described as the "ramp angle," and the average ramp angle is preferably in the range of 1 to 60 degrees, preferably in the range of 25 to 45 degrees. In the simplest and preferred example, the inclination of the ramp is constant. However, the ramp may also have a different concave or convex shape on at least one axis, but it can always have a shape that slopes monotonically downwards.

[0041] The casting process can be divided into several casting stages. During the first casting stage, the molten glass flows onto the casting mold floor and fills the floor area. During this stage, there is little to no accumulation of glass height in the impact zone area. This can remain in the same place, but vibrational forward and backward movement of the casting strands is also possible. These vibrational forward and backward movements that shift the impact zone are small, typically in the range of 1 to 10 mm.

[0042] For example, the end of the first casting stage is characterized by the point where the branched substreams first merge, thereby increasing the height of the molten glass, or rather, the continuing glass ring. Thus, the second casting stage is also characterized by the upward movement of the molten glass and the beginning of the height accumulation of the glass ring. This means that the molten glass flows into the casting mold, covering the partially cooled glass on the lower side and filling most or all of the casting cavity. Then, in order to equalize the thickness difference with the first casting stage, with the aim of making the filling level of the entire casting cavity approximately equal, the existing inclination of the casting mold can be reduced (to horizontal, and possibly temporarily beyond).

[0043] In the second casting stage, relative movement may also occur between the casting strand and the casting mold, more precisely between the impact zone and the casting cavity. In the second casting stage, for example, the position of the impact zone is shifted outward, preferably onto an "upward ramp" away from the inner wall of the casting cavity. This outward shift of the impact zone on the "upward ramp" may occur intermittently, but preferably continuously, preferably in the direction of the connecting line between the impact zone and the merging zone. The speed of the shift on the upward ramp is constant or variable during the second casting stage, preferably in the range of 1 mm / min to 100 mm / min, preferably in the range of 1 to 30 mm / min.

[0044] The connecting line between the collision zone and the confluence zone preferably extends through the centerline of the ring-shaped casting cavity. In this case, the left and right substreams are of equal length, and the confluence zone is located at the lowest point of the casting cavity in plane E2. If the formation of a confluence zone above plane E2 becomes apparent during the casting process, this can preferably be counteracted by shifting the collision zone relative to the casting mold. The collision zone can be shifted in the azimuthal direction along the outer circumference of the ring-shaped casting cavity, or more easily, and therefore preferably, by lateral movement of the casting mold perpendicular to the aforementioned connecting line, or by tilting the casting mold around and along the connecting line (i.e., by tilting it laterally), or by rotating the casting mold (e.g., around the center of the ring-shaped casting cavity). During the relative shift of the collision zone, the height distance between the exit of the glass strand and the collision point is preferably kept constant. This means, for example, that if the collision zone reaches a ramp with an incline, the relative shift movement of the collision zone will follow the (straight or curved) shape of the ramp in the direction of the shift.

[0045] The term “casting process” as used herein and hereafter refers to the entire process of pouring molten glass into a casting mold, including first and second casting stages and optionally a third casting stage. The third casting stage may include measures taken after the casting mold is fully filled in order to complete the actual casting process.

[0046] As a result of the collision zone shifting along the upward ramp, the casting cavity continues to be filled with molten glass during the second casting stage, and the vertical distance between the exit of the casting strand and the surface of the molten glass in the collision zone may become shorter. To keep this distance constant, the casting mold is favorably lowered during the second casting stage.

[0047] As a result of a preferably continuous shift of the impact zone and a preferably continuous descent of the casting mold, the glass molten material is deflected from the impact zone into the casting cavity, such that the meniscus of glass molten material flowing into the casting cavity remains substantially constant, even though the molten level expands and fills the casting cavity.

[0048] During the casting process, the ramp typically forms a closed surface upon which the casting strands strike. However, in a preferred modification of the method, the ramp may be openable and optionally have an opening that can be closed. Before filling of the casting cavity begins, the opening is open so that the casting strands fall downward through the opening. By closing the opening, the casting strands are cut and deflected away from the direction of vertical fall from the ramp towards the casting cavity floor.

[0049] The opening and closing of the ramp is performed, for example, by a part of the ramp that is movable horizontally and radially in the direction of the central axis of the casting mold, and is hereafter referred to as the “slider”. The slider can be considered as part of a multi-part ramp or part of a multi-part casting mold. When the ramp is open, the slider is positioned at a distance from the rest of the casting mold, and a “casting gap” is created. In this case, the casting gap forms the opening of the ramp. At the start of the casting process, the ramp (casting gap) is open, and the casting strands extend freely downward through the casting gap. The casting strands are then collected, for example, in a container. The casting gap is closed by pushing the slider toward the rest of the casting mold. The casting strands, initially oriented vertically, are cut as if cut with scissors, strike the ramp in the collision zone, and then flow further downward through the ramp at an angle of less than 90 degrees, as described above in more detail with reference to the description of the ramp. When closed, the slider forms part of the ramp.

[0050] Therefore, the first advantageous function of the slider is to close the casting gap and separate the glass strand flowing vertically through the casting gap from above. The second advantageous function of the slider is to deflect the glass strand in the direction of the central axis of the casting mold so that the outflow of the substream is redirected from the collision zone towards the confluence zone. It has also been found to be useful if the slider is adjacent to the casting cavity floor and in tangential contact, for example, around the periphery of the casting cavity floor, when the casting gap is closed.

[0051] The flow rate of the molten glass is preferably measured in the range of 150 mL / min to 3000 mL / min, and particularly preferably in the range of 300 mL / min to 1500 mL / min. The flow rate of the molten glass is preferably constant during the casting process, but may be variable.

[0052] The method according to the present invention is particularly suitable for processing low-viscosity glass melts. The viscosity during supply is preferably in the range of 10 to 10,000 dPa·s, and particularly preferably in the range of 100 to 1,000 dPa·s.

[0053] The incoming molten glass heats the casting mold during the casting process. It has been found that heating the casting mold is particularly advantageous at the start of the casting process to prevent rapid cooling of the molten glass on the walls of the casting cavity.

[0054] Heating the casting mold has been shown to be advantageous in reducing the high heat loss of the molten glass in the walls of the casting cavity. Heating is preferably carried out electrically, for example inductively, by radiant heating, or by a heating cartridge. The heating temperature depends on the temperature / viscosity profile of the given glass. For example, the heating temperature is in the range below the so-called transformation or glass formation temperature Tg, e.g., the temperature range of Tg-300°C to Tg. Heating has a positive effect on the flow properties by reducing the risk of crack formation during the cooling of the glass ring and preventing excessively rapid cooling below Tg. Alternatively or additionally, insulating the casting mold is also advantageous, for example, by placing refractory material above the casting mold, or by actively heating the molten glass in the casting mold from above, for example, by a gas flame or porous burner.

[0055] In a modified version of the preferred method, the inner wall and / or outer wall of the casting cavity are conical and movable perpendicular to the casting cavity floor.

[0056] The inner wall is formed, for example, by a movable cylinder or ring, preferably a cone. During the cooling process of the molten glass, the cylinder / cone (i.e., the inner wall of the casting cavity) can be moved vertically, preferably by a few millimeters, thereby creating a gap between the solid glass body and the inner wall of the casting cavity. In the case of a conical inner wall, it is irrelevant whether the cone tapers upward or downward. That is, the vertical movement during cooling always occurs such that the diameter of the inner wall decreases compared to the inner diameter of the glass ring, thus creating a gap, which in turn avoids wedge formation when removing the glass ring from the casting mold.

[0057] With respect to an apparatus for manufacturing glass rings from multi-component glass, the aforementioned objective is achieved by an apparatus having the features of claim 11.

[0058] The device (a) A casting mold comprising a ring-shaped casting cavity extending around a central axis, having a casting cavity height and a casting cavity floor, and defined by an inner wall and an outer wall, and a casting cavity opening facing the casting cavity floor, (b) An outlet for supplying molten glass to the casting mold, (c) A moving unit for the spatial movement of the exit and / or casting mold, It is equipped with.

[0059] The moving unit helps to position the casting mold at a specified position and / or orientation relative to the exit, and / or move the casting mold along a specified travel path relative to the exit. The required positioning and movement of the casting mold or exit is preferably performed by the moving unit in a computer-controlled manner.

[0060] For this purpose, the moving unit preferably has means for rotating and tilting components such as joints and pivot axes, and means for translating and displacing components in three spatial directions x, y, and z, where "z" represents the height direction, such as a linear unit.

[0061] This device has displacement, tilting, rotation, and / or sliding functions. In particular, it is possible to position the casting strand emerging from the outlet so that it strikes a collision zone and flows from there toward the inner wall of the casting cavity, where it splits into a right substream and a left substream. The substreams flow together in a confluence zone within the casting cavity, as described above in the description of the method according to the present invention.

[0062] The collision zone is preferably located at the upper height level E1, and the merging zone is located at the lower height level E2.

[0063] The apparatus is suitable for carrying out the method according to the present invention. Advantageous embodiments of the apparatus according to the present invention can be found in the dependent claims. To the extent that the embodiments of the apparatus specified in the dependent claims pattern to the method referred to in the dependent claims in the method according to the present invention, the above descriptions relating to the corresponding method claims are referred to for supplementary explanation.

[0064] With respect to glass rings made of multi-component glass, the aforementioned objective is achieved by a glass ring having the features of claim 16.

[0065] This glass ring can be manufactured using the method according to the present invention. Substreams flowing around the inner wall of the casting cavity and converging in the confluence zone form a casting streak in the area at the azimuthal position of the confluence zone, and this streak partially or preferably completely passes through the ring cross-section in the radial direction. The optical detectability of the casting streak in the glass ring is improved when it causes an optical path difference of at least 30 nm in multi-component glass.

[0066] Because only a single casting streak exists across the entire ring cross-section, it can function as a positioning marker. This is useful, for example, in applications where a specific circumferential position of a glass ring must be maintained, or in systems where the same glass ring must be reinstalled in the same location with the same positioning after removal.

[0067] Multicomponent glass is characterized by high purity, exemplified by the fact that impurities of Cr, Mn, Fe, Co, and Ni, and compounds in each of these elements, are individually less than 50 ppm by weight, particularly preferably less than 20 ppm by weight, and the total amount of impurities of Cr, Mn, Fe, Co, and Ni is less than 100 ppm by weight.

[0068] Furthermore, high-purity multi-component glass is characterized by its superior dry etching stability in reactive ion etching processes (RIE) compared to quartz glass.

[0069] Therefore, glass rings are suitable as plasma etching rings for holding wafers during plasma-assisted dry etching. Glass rings typically have an outer diameter in the range of 300 to 500 mm, a wall thickness of more than 10 mm, and a height of at least 5 mm.

[0070] Definition and measurement method The individual terms used in the above description are further defined below. These definitions are part of the description of the present invention. Terms and measurement methods not specifically defined in this specification shall be interpreted according to the International Telecommunication Union (ITU) interpretation. In the event of any inconsistency between one of the following definitions and the remainder of this specification, the statement made elsewhere in this specification shall prevail.

[0071] Multi-component glass A multicomponent glass consists of at least three components. In the simplest and most preferred example, a multicomponent glass is composed of all anions that are oxygen ions (O 2- It is a pure oxide glass consisting of ). Oxygen ions can occupy 100% of the anionic moieties in the glass's network structure. In another equally preferred embodiment, some of the oxygen ions are replaced by fluoride ions. In this case, the multicomponent glass has a network structure with anionic moieties, (100-x)% of the anionic moiety is oxygen ions (O 2- ) is occupied by fluoride ions (F - ) is occupied by, where x is the degree of substitution (%), ranging from 0.1 to 10.

[0072] lamp The lamp can be regarded as part of the casting cavity and also as part of the lateral boundary of the outer wall of the casting mold. The lamp has an inclination in the direction of the casting mold center line and serves to deflect the glass flow emerging from the outlet tube, whereby the glass strands are directed from the vertical direction of the casting cavity floor towards the inner wall of the casting cavity. For this purpose, the lamp can be provided with a closable casting gap.

[0073] Viscosity The processing of the multi-component glass is carried out in the low-viscosity state of the liquid, characterized by a viscosity in the range of 10 1 dPa·s to 10 4 dPa·s, preferably 10 2 dPa·s to 10 3 dPa·s. This viscosity range is typically achieved for multi-component glasses at temperatures in the range of 900 °C to 1500 °C. The measurement of the viscosity is carried out by the shear viscosity method or the rotational viscosity method in accordance with DIN ISO 7884-2 (1998).

[0074] Instead of exponential notation, viscosity values are often specified using the common logarithm in the form of log(dPa·s).

[0075] Streak A streak is a spatially limited variation in the material homogeneity within the glass that causes a local difference in refractive index. The dimensions are in a short range, in the range of about 0.1 mm to about 2 mm. The difference in refractive index (optical path length difference) is usually visible from 30 nm.

[0076] Therefore, streaks can be characterized as optical features. The casting streaks occurring at the junction of the sub-streams are the totality of a number of small defects (streaks) aligned along the radius of the glass ring. The individual streaks have a small circumferential spread, but as a whole, they have a relatively large area extending to the outer edge of the glass ring.

[0077] For optical identification of streaks at the location of the casting marks, the shading method is suitable, as described in the June 2006 Schott AG pamphlet "Technical Information on Optical Instruments TIE-25: Streaks in Optical Glass".

[0078] Measurement of dry etching resistance To measure dry etching resistance, a sample of multi-component glass is subjected to a standard dry etching procedure in an RIE plasma reactor using the following processing steps. a) Test sample has R 4nm or smaller a One flat surface of the test sample is polished to have a surface roughness with a specified value. (b) The polished flat surface is masked with varnish. (c) The polished flat surface is subjected to a dry etching procedure characterized by the following parameters: ● 600 watts of power are supplied to the HF energy source. ●Using an HF energy source, a bias voltage of -100 volts is applied to the test sample with an input power of 10 watts. ●The following process gases are introduced into the reactor chamber: 5 sccm argon, 1 sccm CF4, 0.3 sccm O2. ● The chamber pressure is set to 6 Pa. ● The etching time is 60 minutes.

[0079] Multicomponent glass with an etching rate of less than 50% compared to a standard sample made of synthetic quartz glass (Suprasil; trade name of Heraeus Quarzglas GmbH & Co.KG) is classified as dry etching resistant.

[0080] purity Multicomponent glass is defined herein as "high purity" if the impurities of Cr, Mn, Fe, Co, and Ni in the multicomponent glass, and the individual proportions of compounds in each of these elements, are less than 50 ppm by weight, and the total amount of impurities of Cr, Mn, Fe, Co, and Ni is less than 100 ppm by weight. [Brief explanation of the drawing]

[0081] Exemplary Implementation The present invention will be described in more detail below with reference to exemplary embodiments and drawings. In particular, in the schematic diagram, [Figure 1] This shows a casting mold mounted on a frame for manufacturing a glass ring. [Figure 2] Figure 1 shows a cross-sectional view along line AA', illustrating the details of the casting mold and frame. [Figure 3] A schematic diagram illustrating the height level and inclination of the casting mold is shown. [Figure 4] A schematic diagram illustrating the collision and merging zones during the casting of a glass ring is shown. [Figure 5] A schematic diagram illustrating the method and process for manufacturing a glass ring is shown. [Figure 6] A schematic diagram illustrating the method and process for manufacturing a glass ring is shown. [Figure 7] A schematic diagram illustrating the method and process for manufacturing a glass ring is shown. [Figure 8] A schematic diagram illustrating the method and process for manufacturing a glass ring is shown. [Figure 9] A schematic diagram illustrating the method and process for manufacturing a glass ring is shown. [Figure 10] A schematic diagram illustrating the method and process for manufacturing a glass ring is shown. [Figure 11] A schematic diagram illustrating the method and process for manufacturing a glass ring is shown. [Figure 12] A schematic diagram illustrating the method and process for manufacturing a glass ring is shown.

[0082] Figure 1 schematically shows an embodiment of the apparatus of the present invention in which a casting mold 1 is mounted on a frame 2. The frame 2 comprises a linear unit 2a for positioning the casting mold 2 in the height direction (z direction) and a further linear unit 2b for translating the casting mold 2 in a plane (x direction). The frame 2 also has an electrically movable joint 2c for adjusting the tilt of the casting mold 1. The direction is indicated by coordinate system 3. The movement of the casting mold 1 by the linear units 2a and 2b and the tilt of the casting mold 1 by the joint 2c are performed by computer control.

[0083] The apparatus is used to manufacture glass rings from high-purity multi-component glass by pouring molten glass into a casting mold 1. The casting mold 1 has a circular, closed casting cavity 1a with an open top. A fixed outlet pipe 4 (Figure 2) is located above the casting cavity 1a. Molten glass is supplied to the outlet pipe 4 from a conventional crucible (not shown).

[0084] Further details of the casting mold 1 can be seen in Figure 2. The casting cavity 1a has a circular casting cavity floor 1b on the opposite side of the gap opening, and the circular casting cavity floor 1b is bounded on the outside by a ring-shaped outer wall 1c and on the inside by an inner wall 1d. The outer diameter of the casting cavity 1a is 360 mm, the inner diameter is 300 mm, and the height is 30 mm.

[0085] The inner wall 1d is formed by an insert 1e that tapers slightly conically towards its upper end. During the casting process, the insert 1e closes the central opening of the casting mold 1, which extends coaxially with the central axis 1f. After the casting process, the insert is pushed out downward (y-direction) from the central opening.

[0086] A portion of the outer wall 1c or a portion of the casting cavity floor 1b is formed by a wedge-shaped body 1g, which is displaceable in the radial direction (x direction) and is positioned to leave a casting gap from the casting mold 1 before the casting process. The functions of the wedge-shaped body 1g and the casting gap will be described in more detail below with reference to the method and Figures 6 to 12.

[0087] At the start of the casting process, the casting mold 1 is oriented in space such that the casting cavity floor 1b is inclined with respect to the horizontal. This is indicated by the inclination angle α in the schematic diagram of Figure 3.

[0088] The casting mold 1 is positioned below the outlet pipe 4 (Figure 2) such that the initial impact zone 5 of the casting strand is formed at height level E1. From there, the casting strand flows into the casting cavity 1b and reaches the inner wall 1d of the casting cavity, which acts as a “watershed” in the glass molten material, causing the casting strand to split into a right substream 7a and a left substream 7b. This schematically shown splitting zone 5a is located in the area of ​​the intersection between the inner wall 1d of the casting cavity, as shown in the plan view of Figure 4, and the centerline 1r of the casting mold 1. The two substreams 7a;7b flow downward through the casting cavity 1b according to their inclination and merge in a confluence zone 6 located at height level E2. The impact zone 5, the splitting zone 5a, the confluence zone 6, and the centerline 1s of the casting mold 1, which extends perpendicular to the sheet plane, are all on the centerline 1r. As time passes, the molten glass fills the casting cavity 1a, and casting streaks 6a are formed in the area of ​​the confluence zone 6. Small defects, such as tiny streaks, are visible in the casting streaks 6a. The casting streaks 6a form a visually recognizable aggregate of these small streaks.

[0089] In the exemplary embodiment, the initial inclination of the casting cavity floor 1b is 15 degrees, resulting in a height difference y1 of approximately 61 mm between the height level E1 of the raised end of the casting cavity floor 1b and the height level E2 of the opposite end of the casting cavity floor 1b at a distance of 370 mm between the collision zone 5 and the confluence zone 6.

[0090] The method according to the present invention will be described in more detail below with reference to Figures 1 to 12.

[0091] The glass ring 13 (Figure 12), to be manufactured by casting, has an outer diameter of 360 mm and an inner diameter of 300 mm, with a wall thickness of 30 mm and a height of 25 mm. The casting cavity 1a of the casting mold 1 is designed accordingly.

[0092] A glass molten material having the following composition is melted in a crucible.

[0093] [Table 1]

[0094] At a melting point of approximately 1380°C, the viscosity of the glass is approximately 100 dPa·s.

[0095] Figure 5 schematically shows the casting mold 1, the outlet pipe 4, and the casting strand 8 flowing out of the outlet pipe 4 vertically through the casting mold 1. The casting mold 1 initially has an inclination of 15 degrees relative to the horizontal. A stable jet with a flow rate of 1000 mL / min is established before proceeding. Unused glass lumps are collected in a container.

[0096] Figure 6 schematically illustrates step 1) of the method in which the wedge 1g is pushed radially toward the casting strand 8, as indicated by the directional arrow 1h. The upper surface of the wedge 1g facing the casting mold 1 forms a ramp 1i that slopes downward toward the casting mold 1. The casting strand 8 initially continues to fall through the casting gap 9 formed between the ramp 1i and the casting cavity floor 1b of the casting mold 1.

[0097] Figure 7 shows step 2 of the method, in which the ramp 1i finally closes the casting gap 9 by further pushing the body 1g forward, thereby interrupting the casting strand 8. The casting strand strikes the ramp 1i (Figure 6) in the area of ​​the initial impact zone 5 and is deflected from there onto the casting cavity floor 1b (Figure 4) as indicated by the directional arrow 1k. This initiates the first casting stage. The vertical casting strand 8 strikes the initial impact zone 5 at height level E1 and splits into two substreams 7a and 7b (Figure 4) in the splitting zone 5a, these substreams flow around the insert 1e and merge again in the area of ​​the confluence zone 6 at the lower height level E2, forming the casting streak 12.

[0098] The initial impact zone 5 is located on the surface of a wedge 1i that forms a downwardly inclined ramp for the molten glass 11 flowing into the mold, with an inclination of 30 degrees relative to the mold bed. Along with a 15-degree inclination angle resulting from the initial inclination of the mold bed 1b, this results in an impact surface in the casting strand 8 in the initial impact zone 5 that is inclined 45 degrees downward relative to the horizontal.

[0099] The molten glass 11 cools and solidifies on the walls of the casting cavity 1a, particularly on the casting cavity floor 1b. As the casting cavity 1a continues to fill, the molten front 7c, shown in Figure 4 by the arc-shaped gray region extending across the entire width of the casting cavity 1a, moves the already solidified molten material continuously toward the confluence zone 6 at a nearly constant speed. By layering the molten glass as uniformly as possible, convection and associated streaks are prevented.

[0100] As soon as the casting cavity floor 1b is completely covered with solidified glass molten material, this results in the confluence of the two molten material fronts 7c in the confluence zone 6. To reduce the movement speed of the molten material fronts 7c, the inclination of the casting cavity floor 1b relative to the horizontal is continuously reduced by approximately 15 degrees / minute.

[0101] As a result, in step (3) of the method, the casting mold 1 is gradually moved horizontally, as schematically shown by the direction arrow 1m in Figure 8, and the second casting stage begins. The turning point for the tilting movement is fixed and is located in the outlet area of ​​the outlet pipe 4.

[0102] Simultaneously, the casting mold 1 is continuously lowered relative to the fixed outlet pipe 4 at a speed of approximately 15 mm / min, as indicated by the directional arrow 1n, and is moved along the contour of the ramp so that the outlet pipe 4 maintains a nearly constant distance of approximately 3-5 mm from the level of the molten glass 11.

[0103] Figure 9 schematically shows step (4) of the method in which the mold 1 (Figure 4) reaches horizontally along with the casting cavity floor 1b. The glass molten 11 in the area of ​​the initial impact zone 5 has been cooled to a temperature lower than the softening temperature of the glass and is overflowed with further low-viscosity glass molten 11 to form a horizontal molten surface. By continuously lowering the mold 1 relative to the outlet pipe 4 (direction arrow 1n in Figure 8) and continuously translating the mold 1 as indicated by the direction arrow 1o, a new impact zone 5.1 is formed for the casting strand 8, which remains positioned at approximately the same distance above the ramp 1i of the wedge-shaped body 1g. The new impact zone 5.1 is permanently located at the edge of the formed glass ring, thereby ensuring that the flow direction of the glass molten 11 is always directed toward the center of the mold, or at most deflected laterally, but the glass molten does not flow in the opposite direction.

[0104] The casting process continues until the casting cavity 1 is filled with molten glass 11 to the extent that it reaches the height of the glass ring 13 (Figure 12) to be manufactured. This state (step (5)) is shown in Figure 10.

[0105] The subsequent method step (6) can be referred to as the third casting stage, in which the end of the casting process is initiated when the casting strand 8, still flowing out of the outlet pipe 4, is guided by the wedge-shaped body 1g away from the ramp of the insert 1g along with the remaining casting mold 1, as shown in Figure 11 by the directional arrow 1p, and is displaced to reach the area of ​​the recess 12 of the insert 1g and fall vertically downward into the collection container.

[0106] The movement of the casting mold 1 and the wedge-shaped body 1g in steps (1) to (6) of the method described with reference to Figures 5 to 11 is performed using a computer control system.

[0107] During the further cooling of the molten glass 11, the conical insert 1e is lowered by a few millimeters, as indicated by the directional arrow 1q in Figure 12 (method step (7)). This prevents the high-temperature glass ring 13 from shrinking on the inner wall 1d.

[0108] The resulting ring-shaped glass blank 13 is tempered in a stress-free manner and ground to the desired dimensions of a glass ring, which are almost already achieved by near-net-shape forming in the casting process.

[0109] As a result, a glass ring made of high-purity multi-component glass, characterized by high transparency, high purity, and high plasma resistance, is obtained.

[0110] The high purity of multicomponent glass is demonstrated by the fact that the impurities of Cr, Mn, Fe, Co, and Ni in the multicomponent glass, as well as the individual proportions of compounds of each of these elements, are less than 50 ppm by weight, and the total amount of impurities of Cr, Mn, Fe, Co, and Ni is less than 100 ppm by weight.

[0111] The high plasma resistance of multi-component glass is demonstrated by the fact that, when performing standard dry etching procedures, multi-component glass exhibits an etching rate less than 25% of that of synthetically produced quartz glass (Suprasil).

[0112] The glass ring exhibits characteristic cast streaks 6a (Figure 4) extending over part or all of the cross-section (overall width and overall height) of the glass ring in the area of ​​the former confluence zone 6. The cast streaks 6a have a circumferential extent of less than 2 mm and cause an average path difference of more than 30 nm in the multi-component glass with respect to the measurement beam with a measurement wavelength of 535 nm. The cast streaks can function as positioning markers in systems such as plasma etching systems for semiconductors.

Claims

1. A method for manufacturing a glass ring from multi-component glass, (a) A step of preparing a casting mold (1) which extends around a central axis (1s), has a casting cavity height and a casting cavity floor (1b), and comprises a ring-shaped casting cavity (1a) defined by an inner wall (1d) and an outer wall (1c), and a casting cavity opening facing the casting cavity floor, (b) A process for producing a glass molten product of the multi-component glass, (c) A step of supplying the casting strand (8) of the molten glass into the casting mold (1), wherein the casting strand (8) collides with the collision zone (5; 5.1) and branches into a right substream (7a) and a left substream (7b), the substreams (7a; 7b) converge in the confluence zone (6) within the casting cavity (1a) and fill the casting cavity (1a) to at least a portion of the height of the casting cavity, (d) A step of cooling the molten glass contained in the casting cavity (1a), comprising the steps of forming a ring-shaped blank (13), further processing the ring-shaped blank (13) to form a glass ring, and cooling the material, A method characterized in that a ring-shaped blank is manufactured from the multi-component glass by a casting process including the above.

2. The method according to claim 1, wherein the collision zone is located at an upper height level E1, the confluence zone is located at a lower height level E2, and the casting mold is preferably oriented such that the casting cavity floor is inclined with respect to the horizontal between the height levels E1 and E2, and the inclination is changed during the casting process.

3. The method according to claim 2, characterized in that the position of the impact zone during the first casting stage is located in the area of ​​a ramp that slopes downward from the outside to the inside, and during the second casting stage, the position of the impact zone on the ramp is changed, preferably shifted outward, and the casting mold is preferably lowered during the second casting stage.

4. The method according to claim 3, characterized in that the ramp can be opened and closed, and the casting strand is cut by closing the ramp and deflected from the vertical drop direction toward the casting cavity floor.

5. The method according to claim 1, characterized in that the cast strand is metered to a flow rate in the range of 150 mL / min to 3000 mL / min, preferably in the range of 300 mL / min to 1500 mL / min.

6. The method according to claim 1, characterized in that the molten glass is supplied with a viscosity in the range of 10 to 10,000 dPa·s, particularly preferably in the range of 100 to 1,000 dPa·s.

7. An apparatus for manufacturing glass rings from glass by casting molten glass, (a) A casting mold comprising a ring-shaped casting cavity extending around a central axis, having a casting cavity height and a casting cavity floor, and defined by an inner wall and an outer wall, and a casting cavity opening facing the casting cavity floor, (b) An outlet for supplying the molten glass to the casting mold, Equipped with, The apparatus is characterized in that it has a moving unit for the spatial movement of the outlet and / or the casting mold, wherein the casting mold can be moved relative to the outlet and positioned so that the casting strands emerging from the outlet pipe collide with a collision zone and branch into a right substream and a left substream, and the substreams converge in a confluence zone within the casting cavity.

8. The apparatus according to claim 7, characterized in that the moving unit is designed to adjust the inclination of the casting mold with respect to the horizontal such that the collision zone is located at the upper height level E1 and the confluence zone is located at the lower height level E2.

9. The apparatus according to claim 7, characterized in that the moving unit is designed to lower the casting mold relative to the outlet.

10. The apparatus according to claim 9, characterized in that the casting cavity floor comprises a ramp having an opening that can be closed by a movable slider.

11. A glass ring made of multi-component glass, having a center line and a cross-section, wherein the cross-section is defined by an upper surface, a bottom surface opposite to the upper surface, an outer wall, and an inner wall, and has radial casting marks extending radially with respect to the center line at azimuthal positions within the area between the inner wall and the outer wall.

12. The glass ring according to claim 11, characterized in that the casting marks completely fill the cross-section between the top surface, bottom surface, outer wall, and inner wall.

13. The glass ring according to claim 11, characterized in that the casting marks result in a path difference of at least 30 nm in a measurement beam having a wavelength of 535 nm.

14. The glass ring according to claim 11, characterized by having an outer diameter in the range of 300 to 500 mm and a wall thickness of at least 10 mm.

15. The glass ring according to claim 11, characterized in that the impurities of Cr, Mn, Fe, Co, and Ni in the multicomponent glass, and the individual proportions of compounds in each of these elements, are less than 50 ppm by weight, particularly preferably less than 20 ppm by weight, and the total amount of impurities of Cr, Mn, Fe, Co, and Ni is less than 100 ppm by weight.

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