Method for producing a MAS glass body, powder mixture, MAS glass body and use of a MAS glass body

Abstract

The invention relates to a method for producing a bubble-free, X-ray amorphous MAS glass body with a mass ≥ 3 kg and a surface area to volume ratio ≤ 1.5 cm⁻¹, wherein a bubble-free MAS glass body is present if it has fewer than 5 bubbles per 100 cm⁻³ with a size of 0.1 to 0.2 mm and no bubbles > 0.2 mm, wherein the method comprises the following process steps: a) preparing a powder mixture with 10 to 40 mol% MgO, 5 to 30 mol% Al₂O₃ and 40 to 70 mol% SiO₂ or precursors of these raw materials, as well as with auxiliary elements and impurities, wherein the auxiliary elements are elements of Group I and / or Group II and / or Group IV.Main group and / or Fe, wherein a total content of the auxiliary and foreign elements of at least 10 ppm - 300 ppm, in particular at least 30 ppm - 150 ppm, and particularly preferably at least 50 ppm - 100 ppm, is adjusted; b) Melting the powder mixture provided in step a); c) Cooling the melt produced in step b) and comminuting the cooled melt into particles with a diameter ≤ 10 mm; d) Heating and melting the particles obtained in step c); e) Cooling the melt obtained in step d) to obtain a MAS glass body; and f) Performing a hot isostatic pressing operation on the MAS glass body to obtain a bubble-free MAS glass body.

Description

The present invention relates to a method for producing a MAS glass body, to a powder mixture for producing a MAS glass body, to a MAS glass body and to the use of a MAS glass body according to the invention.Plasma-enhanced dry etching-also referred to as "plasma etching" for short-is an indispensable technology for the production of ultrafine structures of semiconductor devices, high-resolution displays and in solar cell manufacturing.EP 3 708 547 A1 describes a plasma etching in a vacuum reactor at a relatively high temperature and in a highly corrosive atmosphere. In this case, the vacuum reactor is flushed with an etching gas at low pressure. A highly reactive, etching-active plasma is generated by high-frequency discharge between electrodes or by electrodeless microwave discharge.In plasma etching, not only is the desired layer removed from the processed wafer, but as an undesirable side effect also from the components of the etching chamber, which typically consist of quartz glass.Fused silica is particularly suitable because it is relatively etch resistant to the fluorine-containing plasmas used. In addition, silica glass having very high purity can be produced. This is of particular significance for the use of components for plasma etching chambers, since possible impurities in the quartz glass can reach the wafer during the etching process. The cleaner the etched-off quartz glass, the lower the risk of contamination for the wafer during the plasma etching process. Therefore, for sophisticated etching steps, inter alia, quartz glass components made of synthetically produced material with an almost 100% purity grade are used.The lower the impurities in the components of the plasma etching chamber, the better the materials are basically suitable for this demanding application. This general finding also applies to high-quality ceramics which, owing to their high etching resistance, are used in part as a substitute for quartz glass in plasma etching chambers.With regard to the application in etching processes, it is known to avoid all foreign substances, since they could contaminate the wafer in the plasma process. It is therefore known from the prior art to always aim for a maximum purity of the glass components produced and thus of the starting materials used, which corresponds to a minimization of all foreign substances.A low etching rate of the materials or components used can also be advantageous, since the contamination risk likewise decreases with less removed material. Furthermore, a low etching rate of the components of the etching chamber also has advantages with regard to the very precise geometries, which are extremely important with structure widths of less than 10 nm. A lower etch rate results in less device geometry changes during the device life cycle.It is known, for example, from U.S. Pat. No. 7,015,163 B2 or U.S. Pat. No. 7,084,084 B2 that MAS glass is very resistant to plasma etching processes with a fluorine-containing gas atmosphere. During the etching process, the fluorine in the etching atmosphere reacts with the magnesium in the MAS glass and a low-volatile MgF2layer is formed on the surface of the component, which significantly reduces the further etching removal.WO 2022 / 075687 A1 further discloses that an additional MgF2doping of a MAS glass is carried out. However, it has been found that such doping only marginally improves the etching resistance.MgO-Al2O3-SiO2glasses (MAS glasses) have very different physical and chemical properties depending on the chemical composition. The different compositions are found in the literature with different designations, as is illustrated in FIG. 1.It is important when using MAS glass for etching applications that the glass is completely X-ray amorphous, since crystalline regions lead to local variations in the etching removal. These effects, also referred to as etching non-homogeneity, easily lead to "under-etching" and thus to the emission of particles.Despite the known advantages of MAS glass, no industrially attractive products have been known to date. Known is MAS glass in the form of fibers, which are preferably used as reinforcement of the mechanical strength. Attempts to produce light (weight <1 kg) thin-walled annular components are also known. However, for attractive industrial use, compact heavy semi-finished products are required, such as cylinders or rods, from which rings or plates of desired target dimensions can be cut.It is known from the geometry of any body that as the volume increases, the surface area to volume ratio (O / V) decreases because the surface area is square but the volume is cubic (square cube law). This is of decisive importance for the cooling rate of masses of different sizes. The cooling rate is proportional to the size of the surface, but increases more slowly than the volume as the body is enlarged, so that larger masses cool more slowly than small ones.MAS glass must be cooled rapidly from the melting temperature of about 1,300° C. to 1,000 ° C., since this, due to its chemical nature, has a strong tendency to crystallize and separate. Both effects have an extremely negative influence on the further processing and use of the material in the plasma etching process.Thus, the production of large or heavy and compact MAS components with avoidance of crystallization and separation seems not to be possible due to the increasingly slower cooling rate.In addition, it is practically impossible to produce a large MAS component free of bubbles. In addition to bubbles contained in the glass melt itself, so-called casting bubbles also easily arise during the shaping process of the glass, i.e. gas bubbles which are trapped during the casting process of the glass melt.However, when using components in an etching chamber in the semiconductor production process, the existence of bubbles in the glass is very problematic. If a bubble reaches the surface of a component as a result of material being removed during the etching process and opens, particles and foreign substances are released into the process chamber in an uncontrolled manner, which interferes with the production process and can lead to losses in the yield of the production of semiconductor components.In order to avoid bubbles in glass, certain techniques in glass production are known in principle. Refining of glass in the melt is customary, optionally with addition of suitable additives, namely refining agents and by so-called bubbeling. However, such tensile impacts contaminate the produced MAS glass component.In order to examine the properties of the MAS glasses in more detail, glasses having different chemical compositions were produced and the influence on the tendency to separate and crystallize was investigated. The chemical glass compositions of 13 of these MAS samples are summarized in Table 1 and arranged in a phase diagram in Figure 2. Table 1: Glass composition [mol %] of prepared MAS glass samples Table 1: Glass composition [mol %] of prepared MAS glass samples025,65,668,812886423010603131374425195651015756181567727155883515509261262102624501118136912102169The size of each laboratory sample was 300 g.The samples 0-12 shown in Figure 2 were evaluated for glass quality, the glasses being evaluated as follows:Grey (Samples 2, 4, 7, 8, 9, 10): clear glassHatched (Samples 3, 5, 6, 11, 12): Pale glasswhite (samples 0, 1): glasses with segregationsIt is found that there is a preferred range of MAS compositions which provide appealing glasses without increased bubble content and without spontaneous segregations. This region lies in the region• SiO2: 50-65 mol%• MgO: 25-35 mol%• Al2O3: 10-25 mol%If the SiO2content is too high (>70%), the glasses cannot finen well and consequently contain many bubbles.If the Al2O3content is too low (<10%), the MgO no longer dissolves well in the glass, and spontaneous separation occurs.With regard to the etching resistance, the glass composition 2 has proven to be advantageous: SiO260 mol %, MgO30 mol %, Al2O310 mol %. However, this glass is close to the region of spontaneous separation, so that the production of heavy and compact components is particularly difficult.By heat treatment of samples of glass composition 2, the location of the temperature range critical for segregations was determined. For this purpose, samples were placed in an oven at a preset temperature and held there for 60 min. In Fig. 3, these samples are shown.Considering the samples of Figure 3, it is clear that the temperature range between 1,300°C and 1,000 °C is critical for the formation of segregations. In the technological production of components made of MAS glass, the rapid crossing of this temperature range is therefore particularly important.The fact that large and compact components are particularly susceptible to separation has been experimentally confirmed as follows in the production of an annular component:In order to achieve a glass of particularly high purity, as is fundamentally desired by the applications in the etching process of semiconductor production, starting materials of synthetic purity were used:• SiO2: synthetic, impurity <1 ppm• Al2O3: synthetic, impurity <10 ppm• MgO: synthetic, impurity < 30 ppmWeighting the impurities with the mass fractions of the individual components of the glass composition results in a total impurity of the glass, i.e. the fraction of all chemical elements other than Si, Al, Mg or O, of 10<ppm.The inner diameter of the annular member was 300 mm, the outer diameter of the annular member was 400 mm, and the height of the annular member was 25 mm.With these dimensions, with the density of the glass of 2.6 g / cm 3 a weight of the component of 3.57 kg and a surface-to-volume ratio of 1.2 cm -1. result.Surprisingly, it has been found that a heavy and compact component produced according to this recipe exhibits strong segregations after cooling from the melt. This manufactured component, namely a heavy, compact component made of MAS glass when raw materials of synthetic purity and the separation occurring during this, are used, is shown in FIG. 4. A separation as shown in FIG. 4 is particularly surprising in this respect, since a clear glass can be produced with this glass composition in laboratory test at a sample size of 300 g (see FIG. 2, sample 2).The segregations are not as pronounced as shown in FIG. 3 and also exhibit a somewhat different appearance, but it could be demonstrated by electron microscopy that the phenomenon is droplet-shaped segregations.The experiments show very express how critical is the effect of separation for the production of MAS components. It is therefore obvious that in the process of producing MAS components segregations must be largely avoided.In addition to good homogenization of the MAS glass during the melting process, the time in which the sample cools from above 1,300° C. to 1,000 ° C. is critical. In this phase, considerable separation may occur and it is therefore important to minimize this time.In the production of heavy compact bodies, the increasingly unfavorable surface / volume ratio (square cube law) with increasing weight represents a physical limitation in this case. Due to the cubic growing volume with only a square growth of the surface, the thermal energy can be increasingly difficultly dissipated from the central regions of the MAS component. The central material fraction thus remains in the critical temperature zone between 1,000 °C and 1,300 °C for a longer time.FIG. 5 very clearly shows this effect of temperature distribution on cooling a heavy compact sample. A cooling heavy compact MAS body with long-lasting high temperatures in the core region is shown. This illustrates the high heat capacity and the poor heat dissipation in glass bodies to be produced having a mass of >3 kg.Owing to these physical boundary conditions, however, the cooling time in the critical temperature range between more than 1,300° C. to 1,000 ° C. can be shortened only to a limited extent.It is therefore an object of the present invention to eliminate the disadvantages of the aforementioned prior art. In particular, a compact and large MAS glass body is to be provided in a simple manner, which is homogeneous and in which the crystallization and the separation during curing are minimized. Furthermore, the MAS glass body should be X-ray amorphous. In the present case, the MAS glass body should have a weight of more than 3 kg and a surface / volume ratio≤1.5 cm -1. In addition, the MAS glass body should be bubble-free.These objects have surprisingly been achieved by a method for producing a MAS glass body according to claim 1, by a powder mixture for producing a MAS glass body according to claim 8, by a MAS glass body according to claim 11 and by the use of a MAS glass body according to claim 15.Advantageous refinements are described in the dependent claims.Numerous specific details are discussed below to provide a thorough understanding of the present subject matter. It will be apparent, however, to one skilled in the art that the subject matter may be practiced and revised without these specific details.All features of one embodiment may be combined with features of another embodiment if the features of the various embodiments are consistent.The terminology used in the description of the present disclosure is for describing particular embodiments only and is not to be taken as limiting the subject matter. As used in the present specification and claims, the singular forms "a", "an" and "the" are to be understood to include the plural forms as well, unless the context clearly dictates otherwise. This also applies in reverse, i.e. the plural forms also include the singular forms. It will also be understood that the term "and / or" as used herein refers to and includes all possible combinations of one or more of the associated listed items. It will be further understood that the terms "includes," "including," "comprises," and / or "comprising," when used in the present specification and claims, specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.In the present specification and claims, the terms "includes," "comprises," and / or "comprising" may also mean "consisting of," i.e., the presence or addition of one or more other features, steps, operations, elements, components, and / or groups is excluded.The present invention relates to a method for producing a bubble-free, X-ray amorphous MAS glass body witha mass ≥3 kg anda surface / volume ratio ≤ 1.5 cm -1comprising the process steps: a) preparing a powder mixture comprising 10 to 40 mol % of MgO, 5 to 30 mol % of Al 2 O 3 and 40 to 70 mol % of SiO 2 or precursors of these raw materials, and also comprising auxiliary elements and foreign elements, wherein the auxiliary elements are elements of main group I and / or main group II and / or main group IV and / or Fe, wherein a total content of the auxiliary elements and foreign elements is adjusted to be at least 10 ppm-300 ppm, in particular to be at least 30 ppm-150 ppm, particularly preferably to be at least 50 ppm-100 ppm; b) melting the powder mixture provided in step a); c) cooling the melt prepared in step b) and crushing the cooled melt into particles having a diameter ≤ 10 mm; d) heating and melting the particles obtained in step c); e) cooling the melt obtained in step d) to obtain a MAS glass body; and f) performing a hot isostatic pressing operation on the MAS glass body to obtain a bubble-free MAS glass body.A bubble-free MAS glass body is present in the sense of the invention if it has less than 5 bubbles per 100 cm 3 with the size 0.1 to 0.2 mm and no bubbles >0.2 mmPrecursors of these raw materials are preferably understood to mean the corresponding hydroxides and / or carbonates of MgO and Al 2 O 3.The proportions of the individual elements, as indicated in step a), are preferably determined by the LA-ICP-MS (laser ablation-inductively coupled plasma-mass spectrometry) method. This method is preferably also used for all further stated content or proportion data in a powder mixture and / or a MAS glass body.It is surprising to establish that, when auxiliary elements are added to a powder mixture, heavy and compact MAS glass bodies can be produced with significantly better results with regard to crystallization and separation.Advantageously, the entropy of the melt is increased by the addition of auxiliary elements. Consequently, with an increase in entropy, the tendency of the melt to separate is significantly reduced.The mixture entropy is assumed here:Due to the addition of auxiliary elements, a large entropy increase is achieved and thus the Gibbs free enthalpy predominates:The entropy is positive, the contribution to the free enthalpy is thus negative, which means that the mixed state is more favourable in terms of energy at high entropy. Therefore, the melt remains in the mixed state, rather than demix, when auxiliary elements are present in accordance with the invention.The auxiliary elements according to the invention are alkali metals and / or alkaline earth metals and / or Fe. With the aid of these auxiliary elements, particularly good compact and large MAS glass bodies can be produced which have no or virtually no separation. At the same time, the MAS glass bodies produced in this way have been shown to be suitable, as tests have shown, for use in processes for semiconductor production.Auxiliary elements are in particular elements whose content in the powder mixture to be prepared prevents separation during the production of the MAS glass body.Preferably, the auxiliary elements are added during the preparation of the powder mixture during the preparation of the MgO-Al 2 O 3- SiO 2 mixture.With regard to the alkalies and / or alkaline earth metals, Na and / or K and / or Ca and / or Li are particularly preferably used as auxiliary elements.Mixtures of at least two of the elements Na, K, Ca, Li and Fe are preferably used.In the context of the method according to the invention, MgO-Al 2 O 3- SiO 2 mixtures which have auxiliary elements are thus explicitly prepared. Thus, a departure according to the invention from the standard procedure takes place in which as pure powder mixtures as possible without additional elements are used.Particularly preferably, a powder mixture containing auxiliary elements is adjusted as follows:a Na content of at least 2 ppm - 50 ppm and / ora K content of at least 0.5 ppm-50 ppm, in particular at least 0.5 ppm-20 ppm, and / ora Ca content of at least 0.5 ppm - 50 ppm, in particular at least 0.5 ppm - 20 ppm, and / ora Li content of at least 0.5 ppm - 50 ppm, in particular at least 0.5 ppm - 20 ppm, and / ora Fe content of at least 0.5 ppm - 10 ppm, in particular at least 1 ppm - 5 ppm.The foreign elements contained in the prepared powder mixture are preferably elements of main group III and / or main group V and / or transition metals with the exception of Fe.Here, the content of the foreign elements is preferably adjusted such that the content of the elements Cr, Mn, Co, Ni, Ti, Zn and Zr is <2 ppm in each case and / or the content of the elements B, P and Cu is <1 ppm in each case.Preferably, in step a) a powder mixture is prepared which comprises 25 to 35 mol % MgO, 10 to 25 mol % Al 2 O 3 and 50 to 65 mol % SiO 2, particularly preferably 30 mol % MgO, 10 mol % Al 2 O 3 and 60 mol % SiO 2.In a preferred embodiment, the method according to the invention is characterized in that less than 0.01 mol % of material additives comprising fluorine and / or yttrium compounds are added during the preparation of the powder mixture and / or the production of the MAS glass body.Step b) and / or d) is / are preferably carried out with a temperature application of 1200° C. to 2000° C., preferably of 1500° C. to 1750° C.In a preferred embodiment, the process according to the invention is characterized in that steps c), d) and e) are carried out a plurality of times, the melt in step c) in each case being the melt previously produced by step e). Multiple means 2, 3, 4, 5, etc. times. By performing steps c), d) and e) several times, homogeneity can be further improved.In a preferred embodiment, the process according to the invention is characterized in that the duration of step b) is from 0.1 to 10 hours, preferably from 0.1 to 7 hours.In a preferred embodiment, the process according to the invention is characterized in that the duration of step d) is from 0.1 to 10 hours, preferably from 0.1 to 7 hours.In a preferred embodiment, the process according to the invention is characterized in that the mixture from step d) in step e) is cooled to a temperature of below 25° C.In a further preferred embodiment, the process according to the invention is characterized in that the melt from step d) in step e) is initially cooled rapidly to a temperature of 600 to 900° C. and then much more slowly to a temperature of below 25° C.Rapid means, for example, cooling of more than 75 K per minute, preferably of more than 90 K per minute and of less than 120 K per minute. Slow means, for example, a cooling of less than 5 K per minute, preferably of less than 2.5 K per minute and of greater than 0.5 K per minute.Rapid cooling down to the temperature range of 600 to 900° C. has the advantage that the risk of crystallization is minimized, whereby the formation of non-homogeneity is further avoided. The subsequent slow cooling down to room temperature avoids the formation of stresses or cracks.In a preferred embodiment, the process according to the invention is characterized in that the heating of the mixture in steps b) and / or d) takes place in Pt and / or Pt / Rh crucibles.In a preferred embodiment, the method according to the invention is characterized in that the cooling of the melt in step e) is carried out first in a steel mold coated with parting agent and then, after demolding, in the cooling furnace.Step f), i.e. the performance of a hot isostatic pressing operation on the MAS glass body, preferably comprises the following substeps:heating the MAS glass body to a first heating temperature above the glass transition temperature while simultaneously building up a gas pressure of more than 500 bar;bb) maintaining the first heating temperature and the gas pressure for a first holding period;cc) cooling to a first intermediate temperature below the first heating temperature while maintaining the gas pressure;dd) maintaining the first intermediate temperature and the gas pressure for a second holding period;cooling to a second intermediate temperature while maintaining the gas pressure;cooling to a third intermediate temperature while maintaining the gas pressure;gg) cooling with simultaneous reduction of the gas pressure to normal pressure until a final temperature is reached.Preferably, the first heating temperature in step aa) is 830° C. to 950° C., preferably 850° C. to 920° C., more preferably 880° C., and / or the gas pressure in step aa) is 660 bar-2,000 bar, preferably 900 to 1,500 bar, more preferably 1,200 bar.In a particularly preferred embodiment of the invention, the heating temperature in step aa) is 880° and the gas pressure is 1,200 bar.Preferably, the gas pressure reached and set in step aa) is maintained up to step ff) inclusive. Particularly preferably, a gas pressure set in step aa) of 1,200 bar is maintained up to step ff) inclusive.The heating to be carried out in step aa) is preferably carried out at a heating rate of 3 K / min-8 K / min, in particular of 4 K / min-6 K / min, particularly preferably at a heating rate of 5 K / min.In step bb), the first holding time period is preferably 60-120 minutes, in particular 80 minutes-110 minutes, particularly preferably 90 minutes.The cooling described in step cc) is preferably carried out rapidly. In other words, a rapid cooling to the first intermediate temperature, which is below the first heating temperature, takes place. The cooling rate is 20 K / min, for example.The first intermediate temperature is preferably above the glass transition temperature. Preferably, the first intermediate temperature in steps cc) and dd) is 800° C. to 850° C., preferably 82° C. to 80° C., more preferably 830° C.In step dd), the second holding time duration is preferably 60-120 minutes, in particular 80 minutes-110 minutes, particularly preferably 90 minutes.The cooling described in step ee) is preferably carried out slowly. In other words, a slow cooling to the second intermediate temperature, which is below the first intermediate temperature, takes place. The cooling to be carried out in step ee) is preferably carried out at a cooling rate of 0.5 K / min-5 K / min, in particular of 0.75 K / min-1.5 K / min, particularly preferably at a cooling rate of 1 K / min.Preferably, the second intermediate temperature in step ee) is 680° C. to 72° C., preferably 690° C. to 71° C., more preferably 700° C.The cooling described in step ff) is preferably carried out rapidly. In other words, a rapid cooling to the third intermediate temperature, which is below the second intermediate temperature, takes place. The cooling to be carried out in step ff) is preferably carried out at a cooling rate of 4.5 K / min-7 K / min, in particular of 5 K / min-6.5 K / min, particularly preferably at a cooling rate of 6 K / min.The third intermediate temperature is preferably below the glass transition temperature. Preferably, the third intermediate temperature in step ff) is 380 °C to 420 °C, preferably 390 °C to 410 °C, more preferably 400 °C.The cooling described in step gg) is preferably carried out by free cooling of the furnace. In step gg), the furnace is particularly preferably cooled freely and the gas pressure is reduced to normal temperature until a final temperature is reached, this corresponding to the starting conditions before step aa) is carried out.With the aid of the described process parameters in steps aa)-gg), particularly good results can be achieved with regard to the production of a bubble-free MAS glass body.The MAS glass body produced is particularly preferably bubble-free in such a way that it has no bubbles per 100 cm 3 with the size 0.1 to 0.2 mm, particularly preferably no bubbles per 100 cm 3 with the size up to 0.1 mm, very particularly preferably no bubbles per 100 cm 3 with the size up to 0.05 mm.The hot isostatic pressing operation is carried out in corresponding standard industrial plants, as are used, for example, in the ceramic or metal industry for compacting materials. In such plants, temperatures up to 2,000 ° C. and pressures up to 2,000 bar can usually be approached. In a preferred embodiment of the invention, the hot isostatic pressing operation in step f) is carried out in the QIH122 plant from the manufacturer Quintus.In particular, when performing step f), it should be noted that even in this method step (and the associated sub-steps) no segregations occur, which are reliably prevented or avoided, in particular due to the performance of steps a) to e) according to the invention. For this purpose, the above-described heat and pressure program with the preferred ranges is to be used.Particularly preferably, the performance of step f) takes place according to the heating and printing program given below according to the particularly preferred substeps aa)-gg):aa) heating the MAS glass body at a heating rate of 5 K / min to a first heating temperature of 880 °C while simultaneously establishing a gas pressure linearly at 1,200 bar;bb) maintaining the first heating temperature of 880 °C and the gas pressure of 1,200 bar for a first holding time period of 90 minutes;cc) rapid cooling, for example at a cooling rate of 20 K / min, to a first intermediate temperature of 830° C. while maintaining the gas pressure of 1,200 bar; dd) maintaining the first intermediate temperature of 830° C. and the gas pressure for a second holding time period of 90 minutes;slowly cooling at a cooling rate of 1 K / min to a second intermediate temperature of 700° C. while maintaining the gas pressure of 1,200 bar;rapidly cooling at a cooling rate of 6 K / min to a third intermediate temperature of 400° C. while maintaining the gas pressure of 1,200 bar;gg) cooling, with simultaneous reduction of the gas pressure from 1,200 bar to normal pressure, until a final temperature is reached.A further, in particular subordinate, aspect of the invention relates to a powder mixture for producing an X-ray amorphous MAS glass body, in particular for use in a method according to the invention.The powder mixture comprises 10 to 40 mol % of MgO, 5 to 30 mol % of Al2O3and 40 to 70 mol % of SiO2or precursors of these raw materials, preferably 25 to 35 mol % of MgO, 10 to 25 mol % of Al2O3and 50 to 65 mol % of SiO2or precursors of these raw materials, particularly preferably 30 mol % of MgO, 10 mol % of Al2O3and 60 mol % of SiO2or precursors of these raw materials, wherein the powder mixture further comprises auxiliary elements and foreign elements, and the auxiliary elements are elements of main group I and / or main group II and / or main group IV and / or Fe, and the total content of the auxiliary elements and foreign elements is 10 ppm-300 ppm, in particular, 30 ppm-150 ppm, particularly preferably 50 ppm-100 ppm.Similar advantages result as already stated in connection with the method according to the invention.The auxiliary elements are preferably alkali metals and / or alkaline earth metals, in particular Na and / or K and / or Ca and / or Li, and / or Fe, preferably mixtures of at least two of the elements Na, K, Ca, Li and Fe.Particular preference is / are giventhe Na content is at least 2 ppm-50 ppm and / orthe K content is at least 0.5 ppm-50 ppm, in particular at least 0.5 ppm-20 ppm, and / orthe Ca content is at least 0.5 ppm - 50 ppm, in particular at least 0.5 ppm- 20 ppm, and / orthe Li content is at least 0.5 ppm - 50 ppm, in particular at least 0.5 ppm- 20 ppm, and / orthe Fe content is at least 0.5 ppm-10 ppm, in particular at least 1 ppm-5 ppm.The powder mixture preferably has less than 0.01 mol % of material additives comprising fluorine and / or yttrium compounds.The foreign elements of the powder mixture according to the invention are preferably elements of main group III and / or of main group V and / or transition metals with the exception of Fe.Preferably, the content of each of the elements Cr, Mn, Co, Ni, Ti, Zn and Zr is <2 ppm. It is also preferable for the content of the elements B, P and Cu to be <1 ppm in each case.A further, in particular subordinate, aspect of the invention relates to a MAS glass body which can be produced in particular by carrying out the method according to the invention.The MAS glass body according to the invention has a mass ≥3 kg and a surface / volume ratio ≤1.5 cm-1, wherein the MAS glass body is X-ray amorphous.The MAS glass body comprises 10 to 40 mol % of MgO, 5 to 30 mol % of Al2O3and 40 to 70 mol % of SiO2, preferably 25 to 35 mol % of MgO, 10 to 25 mol % of Al2O3and 50 to 65 mol % of SiO2, particularly preferably 30 mol % of MgO, 10 mol % of Al2O3and 60 mol % of SiO2, wherein the MAS glass body further comprises auxiliary elements and foreign elements, and the auxiliary elements are elements of main group I and / or main group II and / or main group IV and / or Fe, wherein the total content of the auxiliary elements and foreign elements is 10 ppm-300 ppm, in particular 30 ppm-150 ppm, particularly preferably 50 ppm-100 ppm, is.The MAS glass body according to the invention is bubble-free in such a way that it has less than 5 bubbles per 100 cm 3 with the size 0.1 to 0.2 mm and no bubbles >0.2 mm.The MAS glass body produced is particularly preferably bubble-free in such a way that it has no bubbles per 100 cm 3 with the size 0.1 to 0.2 mm, particularly preferably no bubbles per 100 cm 3 with the size up to 0.1 mm, very particularly preferably no bubbles per 100 cm 3 with the size up to 0.05 mm.The bubble-free MAS glass body according to the invention is particularly suitable for use in processes of semiconductor production, since it has industrially attractive dimensions with simultaneous bubble freedom according to the above-mentioned specifications and additionally has no segregations.The same or similar advantages result as already stated in connection with the method according to the invention.An X-ray amorphous MAS glass body is a glass without extended regions with crystalline long range order, so that it only yields very widespread X-ray reflections (the so-called glass hillock) in a corresponding examination.X-ray amorphous in the context of the present invention means that no crystalline regions of greater than 10 nm are present in the MAS glass body, which can be determined, for example, with a diffractometer.Preferably, the auxiliary elements are alkalies and / or alkaline earth metals and / or Fe.With regard to the alkalies and / or alkaline earth metals, the auxiliary elements are particularly preferably Na and / or K and / or Ca and / or Li.The MAS glass body preferably comprises mixtures of at least two of the elements Na, K, Ca, Li and Fe.Particular preference is / are giventhe Na content is at least 2 ppm-50 ppm and / orthe K content is at least 0.5 ppm-50 ppm, in particular at least 0.5 ppm-20 ppm, and / orthe Ca content is at least 0.5 ppm - 50 ppm, in particular at least 0.5 ppm- 20 ppm, and / orthe Li content is at least 0.5 ppm - 50 ppm, in particular at least 0.5 ppm- 20 ppm, and / orthe Fe content is at least 0.5 ppm-10 ppm, in particular at least 1 ppm-5 ppm.The MAS glass body preferably has less than 0.01 mol % of material additives comprising fluorine and / or yttrium compounds.The foreign elements of the MAS glass body according to the invention are preferably elements of main group III and / or of main group V and / or transition metals with the exception of Fe.Preferably, the content of each of the elements Cr, Mn, Co, Ni, Ti, Zn and Zr is <2 ppm. It is also preferable for the content of the elements B, P and Cu to be <1 ppm in each case.Due to the stated content of the above-mentioned foreign elements, elements which can promote crystallization, such as Ti and Zr, are kept very low or preferably avoided. In addition, the MAS glass bodies according to the invention have such a composition that are not harmful to processes of semiconductor production.The MAS glass body may have a ring shape, or a cylinder shape, or a rod shape. The formation of a cylindrical shape enables, for example, the later production of ring-shaped MAS glass components.The present invention also relates to a component comprising the MAS glass body described above.All definitions and preferred embodiments listed above for the method according to the invention and the MAS glass body according to the invention apply analogously to the component.In a preferred embodiment, the MAS glass body according to the invention or a component produced from an MAS glass body according to the invention is used in semiconductor production, preferably in an etching chamber.This use of a MAS glass body specified according to the invention also relates to MAS glass bodies which are produced by the method according to the invention.All definitions and preferred embodiments listed above for the method according to the invention and the MAS glass body according to the invention apply analogously to the use of the MAS glass body and / or of the component.The invention is explained in more detail below with reference to non-limiting examples.Embodiment 1:To produce a MAS glass body, a powder mixture was prepared, the oxides of the elements Si, Al and Mg being weighed out and mixed as starting materials in the following composition:- MgO: 30 mol%- Al2O3: 10 mol%- SiO2: 60 mol%The proportion of auxiliary elements and foreign elements was adjusted to 60 ppm in the mixture, whereCa content of: 10 ppm,Fe content of: 1.5 ppm,Na content: 35 ppm,K content of: 6 ppm,Content of foreign elements, namely Mn, Cr and Zr, was set to <1 ppm.A sample amount of 300 g was melted in a Pt / Rh crucible at 1,650 °C for 3:00 hours. The melt was then poured into cold, deionized water.The frits thus formed were ground and re-melted at 1,650 °C for 6:40 hours. For the determination of the second melting time, the melt was observed and melted until a clear and bubble-free melt had formed.After the second melting, the glass was poured into a metal mold.A clear MAS glass body without segregations was obtained.Embodiment 2:In a further exemplary embodiment, the powder mixture according to exemplary embodiment 1 was prepared and a sample quantity of 3 kg was produced. The ground frit was melted in a large Pt / Rh crucible and then poured into a metallic ring shape. A clear ring without segregation was obtained, having an outer diameter of 400 mm, an inner diameter of 300 mm and a height of 21 mm. This MAS glass body in ring form is shown in FIG. 6 and shows no signs of segregation.Exemplary Embodiment 3:The production of a MAS glass body in the form of a ring according to Example 3 was carried out, a hot isostatic pressing operation subsequently being carried out on the MAS glass body in the QIH122 plant from the manufacturer Quintus.The hot isostatic pressing operation was carried out according to the following partial steps:aa) heating the MAS glass body at a heating rate of 5 K / min to a first heating temperature of 880 °C while simultaneously establishing a gas pressure linearly at 1,200 bar;bb) maintaining the first heating temperature of 880 °C and the gas pressure of 1,200 bar for a first holding time period of 90 minutes;cc) rapid cooling at a cooling rate of 20 K / min to a first intermediate temperature of 830° C. while maintaining the gas pressure of 1,200 bar;dd) maintaining the first intermediate temperature of 830° C. and the gas pressure for a second holding time period of 90 minutes;slowly cooling at a cooling rate of 1 K / min to a second intermediate temperature of 700° C. while maintaining the gas pressure of 1,200 bar;rapidly cooling at a cooling rate of 6 K / min to a third intermediate temperature of 400° C. while maintaining the gas pressure of 1,200 bar;gg) cooling, with simultaneous reduction of the gas pressure from 1,200 bar to normal pressure, until a final temperature is reached.After this treatment, the entire ring was free of bubbles visible to the naked eye, i.e. in particular free of bubbles greater than 0.1 mm.Exemplary Embodiment 4:When processing a MAS glass body in the context of a hot isostatic pressing process, it has been found that here too the phenomenon of separation must be taken into account. It has been found that the bubbles can be removed in principle from a temperature of 830° C. and a pressure of 2,000 bar.However, to simplify the process, it is desirable to operate at lower pressures. In order to still achieve the removal of the bubbles at a lower pressure, a slight increase in the temperature is necessary. However, it should be noted that the demixing phenomenon occurs from a certain temperature.This phenomenon was also observed in comparative experiments.The MAS glass body sample shown in FIG. 7 awas treated with a heating temperature of 830° C. and the gas pressure of 2,000 bar in the course of the hot isostatic pressing process in steps aa) and bb). The MAS glass body sample is free from segregation and, according to the definitions given above, is free from bubbles.The MAS glass body sample shown in FIG. 7 bwas also treated in the context of the hot isostatic pressing process, wherein a heating temperature of 90° C. and a gas pressure of 490 bar prevailed in steps aa) and bb). According to the definitions given above, the MAS glass body sample is bubble-free but exhibits segregations.FIG. 8 shows, on an enlarged scale, the separation occurring according to FIG. 7 b, i.e. the separation occurring which can occur at process parameters of the hot isostatic pressing process which are not in the preferred heating temperature and pressure rangeIn order to reliably remove the bubbles and at the same time to avoid separation, a process procedure with a heating temperature of 880 °C and a gas pressure of 1,200 bar has proven particularly suitable.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedEP 3 708 547 A1

[0003] U.S. Pat. No. 7,015,163 B2

[0009] U.S. Pat. No. 7,084,084 B2

[0009] WO 2022 / 075687 A1

[0010]

Claims

A method for producing a bubble-free, X-ray amorphous MAS glass body having - a mass ≥ 3 kg, - a surface / volume ratio ≤ 1.5 cm -1, wherein a bubble-free MAS glass body is present if it has less than 5 bubbles per 100 cm 3 with the size 0.1 to 0.2 mm and no bubbles >0.2 mm, wherein the method has the following method steps: a) preparing a powder mixture having 10 to 40 mol% MgO, 5 to 30 mol% Al 2 O 3 and 40 to 70 mol% SiO 2 or precursors of these raw materials, and also having auxiliary elements and foreign elements, wherein the auxiliary elements are elements of main group I and / or main group II and / or main group IV and / or Fe, wherein a total content of the auxiliary elements and foreign elements of at least 10 ppm-300 ppm, in particular of at least 30 ppm-150 ppm, particularly preferably of at least 50 ppm-100 ppm, is adjusted; b) melting the powder mixture provided in step a); c) cooling the melt produced in step b) and comminution of the cooled melt to particles having a diameter ≤ 10 mm; d) heating and melting the particles obtained in step c); e) cooling the melt obtained in step d) to obtain a MAS glass body; and f) performing a hot isostatic pressing operation on the MAS glass body to obtain a bubble-free MAS glass body.Method according to Claim 1, characterized in that alkali metals and / or alkaline earth metals, in particular elements Na and / or K and / or Ca and / or Li, and / or Fe, preferably mixtures of at least two of the elements Na, K, Ca, Li and Fe, are used as auxiliary elements.Method according to Claim 2, characterized in that - a Na content of at least 2 ppm - 50 ppm and / or - a K content of at least 0.5 ppm - 50 ppm, in particular at least 0.5 ppm - 20 ppm, and / or - a Ca content of at least 0.5 ppm - 50 ppm, in particular at least 0.5 ppm - 20 ppm, and / or - a Li content of at least 0.5 ppm - 50 ppm, in particular at least 0.5 ppm - 20 ppm, and / or - an Fe content of at least 0.5 ppm - 10 ppm, in particular at least 1 ppm - 5 ppm, is established.Method according to one of the preceding claims, characterized in that the foreign elements are elements of main group III and / or of main group V and / or transition metals with the exception of Fe.Process according to Claim 4, characterized in that the content of the elements Cr, Mn, Co, Ni, Ti, Zn and Zr is in each case <2 ppm and / or the content of the elements B, P and Cu is in each case <1 ppm.Method according to one of the preceding claims, characterized in that in step a) a powder mixture is prepared which comprises 25 to 35 mol % MgO, 10 to 25 mol % Al 2 O 3 and 50 to 65 mol % SiO 2, particularly preferably 30 mol % MgO, 10 mol % Al 2 O 3 and 60 mol % SiO 2.Process according to one of the preceding claims, characterized in that step b) and / or d) is carried out with a temperature application of 1200°C to 2000°C, preferably of 1500°C to 1750°C.Method according to one of the preceding claims, characterized in that step f) comprises the following substeps: aa) heating the MAS glass body to a first heating temperature above the glass transition temperature while simultaneously building up a gas pressure of more than 500 bar; bb) maintaining the first heating temperature and the gas pressure for a first holding time period; cc) cooling to a first intermediate temperature below the first heating temperature while maintaining the gas pressure; dd) maintaining the first intermediate temperature and the gas pressure for a second holding time period; ee) cooling to a second intermediate temperature while maintaining the gas pressure; ff) cooling to a third intermediate temperature while maintaining the gas pressure; gg) cooling while simultaneously reducing the gas pressure to normal pressure until a final temperature is reached.Method according to claim 8, characterised in that the first heating temperature in step aa) is 830 °C to 950 °C, preferably 850 °C to 920 °C, more preferably 880 °C, and / or the gas pressure in step aa) is 660 bar - 2,000 bar, preferably 900 to 1,500 bar, more preferably 1,200 bar.Powder mixture for producing a bubble-free, X-ray-amorphous MAS glass body, in particular for use in a method according to one of Claims 1 to 9, wherein the powder mixture comprises 10 to 40 mol% of MgO, 5 to 30 mol% of Al 2 O 3 and 40 to 70 mol% of SiO 2 or precursors of these raw materials, preferably 25 to 35 mol% of MgO, 10 to 25 mol% of Al 2 O 3 and 50 to 65 mol% of SiO 2 or precursors of these raw materials, particularly preferably 30 mol% of MgO, 10 mol % of Al 2 O 3 and 60 mol % of SiO 2 or precursors of these raw materials, wherein the powder mixture further comprises auxiliary elements and foreign elements, wherein the auxiliary elements are elements of main group I and / or main group II and / or main group IV and / or Fe, and the total content of the auxiliary elements and foreign elements is 10 ppm-300 ppm, in particular 30 ppm-150 ppm, particularly preferably 50 ppm-100 ppm.MAS glass body, in particular produced by a method according to one of Claims 1 to 9, having a mass ≥ 3 kg and a surface / volume ratio ≤ 1.5 cm -1, wherein the MAS glass body is X-ray amorphous and bubble-free in such a way that it has less than 5 bubbles per 100 cm 3 with the size 0.1 to 0.2 mm and no bubbles >0.2 mm, wherein the bubble-free MAS glass body has 10 to 40 mol% MgO, 5 to 30 mol% Al 2 O 3 and 40 to 70 mol% SiO 2, preferably 25 to 35 mol% MgO, 10 to 25 mol % of Al 2 O 3 and 50 to 65 mol % of SiO 2, particularly preferably 30 mol % of MgO, 10 mol % of Al 2 O 3 and 60 mol % of SiO 2, and furthermore comprises auxiliary elements and foreign elements, wherein the auxiliary elements are elements of main group I and / or main group II and / or main group III and / or Fe, and the total content of the auxiliary elements and foreign elements is 10 ppm-300 ppm, in particular 30 ppm-150 ppm, particularly preferably 50 ppm-100 ppm.MAS glass body according to Claim 11, characterized in that the auxiliary elements are alkalis and / or alkaline earth metals, in particular Na and / or K and / or Ca and / or Li, and / or Fe, preferably mixtures of at least two of the elements Na, K, Ca, Li and Fe, wherein preferably - the Na content is at least 2 ppm - 50 ppm and / or - the K content is at least 0.5 ppm - 50 ppm, in particular at least 0.5 ppm - 20 ppm, and / or - the Ca content is at least 0.5 ppm - 50 ppm, in particular at least 0.5 ppm - 20 ppm, and / or - the Li content is at least 0.5 ppm - 50 ppm, in particular at least 0.5 ppm - 20 ppm, and / or - the Fe content is at least 0.5 ppm - 10 ppm, in particular at least 1 ppm-5 ppm is / are.The MAS glass body according to claim 11 or 12, characterized in that the foreign elements are elements of main group III and / or of main group V and / or transition metals with the exception of Fe, wherein preferably the content of the elements Cr, Mn, Co, Ni, Ti, Zn and Zr is in each case <2 ppm and / or the content of the elements B, P and Cu is in each case <1 ppm.The MAS glass body according to any one of claims 11 to 13, characterized in that the MAS glass body has a ring shape or a cylindrical shape or a rod shape.Use of a MAS glass body according to one of Claims 11 to 14 or of a component produced from a MAS glass body according to one of Claims 11 to 14 in an etching chamber.

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