Use of glass for passivating electronic components and passivated electronic component

Abstract

The invention relates to the use of a glass for passivating an electronic component, in particular a semiconductor component, to a method for producing an electronic component passivated using the glass, said glass being free of Pb except for being present at most in the form of impurities, and to a passivated electronic component. And comprising the following components in wt% of oxides (see the following table): wherein RO is the sum of BaO + MgO + CaO + SrO and the ratio of (RO + B2O3) / (SiO2 + Al2O3) is at least 0.39, and wherein the difference of BaO-B2O3 is at least 2.0 wt%.

Description

Technical Field

[0001] The present invention relates to the use of glass in passivating electronic components (particularly semiconductor components), a method for manufacturing electronic components using glass passivation, and a passivated electronic component. Background Technology

[0002] Passivation of electronic components mainly refers to the formation or presence of a stable layer (called a "passivation layer") on the electronic components.

[0003] Passivation, or a passivation layer, protects components during manufacturing and / or use from mechanical damage and other harmful effects, such as chemical reactions. High-voltage applications (e.g., diodes with reverse voltages exceeding 1 kV) are only possible with passivation using materials with high breakdown strength. Air has a breakdown strength of 1 kV / mm, far insufficient for manufacturing compact high-voltage electronic devices without passivation. Typically, electronic components are passivated by applying a passivating agent composed of or containing glass, usually forming a thin passivation layer on the component. This passivation provides mechanical protection to electronic components (such as diodes, variable resistors, thyristors, transistors, power transistors, such as insulated-gate bipolar transistors (IGBTs), etc.) and also ensures the stability of their electrical characteristics. For the purposes of this disclosure, the term "electronic component" should be interpreted broadly to include underlying intermediate products made of semiconductor materials, such as wafers or other substrates. Passivation layers are typically applied directly to the pn junction of a semiconductor. At the pn junction, the entire voltage, such as the reverse voltage of a diode, drops by several micrometers over the space charge region, generating an extremely high electric field strength on the order of 20 kV / mm or higher. Passivation is crucial wherever such a high electric field region appears at the edge of the device.

[0004] Passivating agents, particularly glasses and solders, are known in the prior art for passivating semiconductors (e.g., for back-end passivation of silicon wafers or front-end passivation of diodes). The purpose of these glasses is to passivate pn junctions. Excellent passivation is characterized by high breakdown voltage and low leakage current.

[0005] In methods for manufacturing glass-coated electronic components, particularly semiconductor components, a layer comprising a suitable glass is applied to the electronic component. For this purpose, a liquid-phase coating process is typically employed, wherein a liquid or slurry formulation (i.e., a solid-liquid mixture) comprising powdered glass (i.e., glass powder) is applied in layer form by a suitable coating method. Suitable methods may include, for example, spin coating, spray coating, dip coating, casting, brush coating, screen printing, pad printing, inkjet printing, offset printing, roll coating, blade coating, or other methods known to those skilled in the art. The formulation may be, for example, a suspension, slurry, etc. The preparation of the layer may also include electrophoresis. Subsequently, the applied glass layer is fired by heating the electronic component, thereby forming a hermetically sealed glass body on the component. To reduce the risk of damage to the component from high temperatures and to reduce process costs, firing should be performed at the lowest possible temperature. Therefore, the glass used for passivation of electronic components should have a low melting temperature, i.e., the lowest possible softening temperature.

[0006] Currently, many low-melting-temperature passivated glasses in practical use contain lead. Lead glass has excellent acid resistance (especially resistance to HF and HNO3) and a low softening temperature. However, for environmental reasons, lead should be replaced.

[0007] Lead-free passivating glasses, such as those in the Zn-B-Si glass system, are described in literature (JP S61-242928 A, JP 2016-222498 A2, DE 102006062428 A1). Zinc borate glasses are ideally suited for passivation, but their chemical resistance is insufficient. However, excellent chemical acid resistance is crucial for passivating glasses because after a passivation layer is applied to components, such as silicon wafers, the components must be acid-washed or otherwise treated for cleaning purposes. For this purpose, HNO3 or HF is commonly used in the semiconductor industry. Depending on the acid concentration and processing time, the passivation layer can be severely damaged by the acid. Furthermore, ZnO-rich glasses may form undesirable crystalline phases such as zinc borates when heated.

[0008] Furthermore, literature (WO 2018 / 026402 A1) also describes lead-free passivation glasses belonging to the Bi-B glass system. Compared with the zinc borate glasses mentioned above, bismuth-containing glasses have better chemical resistance; however, in addition to the high cost of raw materials, their main drawback is that during semiconductor passivation, due to the low-oxygen atmosphere used, bismuth may be reduced to metallic bismuth. This generates bubbles, resulting in unpassivated regions at the pn junction.

[0009] US 20170323791 A1 discloses a method for manufacturing a semiconductor device comprising a glass layer containing lead-free and alkali-free aluminoborosilicate glass with alkaline earth metal oxides and ZnO. The glass layer exhibits high resistance to etchants containing hydrofluoric acid (6%). The glass layer can be prepared by electrophoresis or screen printing without an exposure step. Due to the high ZnO content, the glass layer may have lower resistance to acidic etchants used for cleaning. Furthermore, because the glass composition of US20170323791 A1 has a high Al₂O₃ and / or SiO₂ content and a low BaO content, its softening temperature is high, requiring a high firing temperature.

[0010] CN 101186442 A discloses an insulating high-resistivity glass for metal sealing. US 20030124774 A discloses an alkali-containing glass for semiconductor applications.

[0011] The EU RoHS Directive (EU Directive 2011 / 65 / EU, Restriction of Hazardous Substances) prohibits the use of leaded glass, but due to exemptions, this ban is not yet in effect in all regions. The ban requires the replacement of leaded glass with lead-free alternatives. Ideally, existing, mature passivation processes require little or no modification to accommodate the new passivating agent. For example, the new passivating agent should have the lowest possible melting or softening temperature, specifically not exceeding 950°C, to achieve a cost-effective passivation process without compromising the stability of electronic components, such as silicon wafers. Furthermore, the passivating agent should exhibit high acid resistance, and its coefficient of linear thermal expansion (CTE) (20°C–300°C) should be suitable for the materials used in the substrates, leads, and electrodes of electronic components (e.g., silicon, SiC, SiN, GaAs, GaN, AlN, and / or mixtures thereof), particularly wide-bandgap semiconductors.

[0012] Therefore, only specific glasses with specific properties can be used for passivation. Summary of the Invention

[0013] The purpose of this invention is to meet the above-mentioned needs and avoid the above-mentioned defects.

[0014] The present invention achieves the above-mentioned objectives through the following means: the use of the selected glass in passivating electronic components according to claim 1, a method for manufacturing glass-passivated electronic components according to claim 8, and a passivated electronic component according to claim 10. Advantageous improvements are further described in the dependent claims and the specification.

[0015] use On one hand, the present invention relates to the use of glass in passivating electronic components, particularly semiconductor components, wherein the glass is free of Pb except in the form of impurities, and comprises the following components by weight percent of oxides: Wherein, RO is the sum of BaO + MgO + CaO + SrO, and the ratio of (RO + B2O3) / (SiO2 + Al2O3) is at least 0.39. Preferably, the difference between BaO and B2O3 is at least 2.0% by weight.

[0016] The inventors have recognized that, in order to meet the requirements for passivated glass, it is important to select the above-mentioned components within a given range, while ensuring a sufficiently high minimum BaO content, because BaO can significantly lower the softening temperature compared to other alkaline earth metal oxides (i.e., MgO, CaO, SrO). Furthermore, the glass contains a specific ratio of RO and B2O3 (i.e., RO+B2O3) to lower the softening temperature and SiO2 and Al2O3 (i.e., SiO2+Al2O3) to promote acid resistance.

[0017] This lead-free glass (i.e., Pb-free glass) is well-suited for passivating electronic components, particularly semiconductor components (such as diodes, thyristors, variable resistors, transistors, power transistors (e.g., IGBTs), and similar electronic components), as well as intermediate products (such as substrates, wafers, etc.). The materials for the electronic components or substrates can include, for example, silicon, SiC, SiN, GaAs, GaN, AlN, and / or mixtures thereof, i.e., particularly wide-bandgap semiconductors. Advantageously, the glass exhibits excellent acid resistance comparable to lead-passivated glass and a sufficiently low softening temperature for the passivation process.

[0018] In an advantageous embodiment, the softening temperature (Ew; i.e., softening point) of the glass is at most 930°C, preferably at most 900°C, and more preferably at most 880°C, to maintain a low firing temperature for forming the passivation layer. The softening temperature refers to the temperature at which the glass melt viscosity is 10... 7.6 The temperature at dPas. A lower limit of the advantageous softening temperature may be at least 600°C, preferably at least 650°C, more preferably at least 700°C or at least 750°C. The softening temperature may be in the range of 600°C to 930°C, particularly in the range of 650°C to 900°C, or in the range of 700°C to 880°C.

[0019] To achieve cost-effective glass production, in an advantageous embodiment, the glass processing temperature (Va; i.e., processing point) is at most 1200°C, preferably at most 1180°C, and in some advantageous variations at most 1150°C. The processing temperature refers to the temperature at which the melt viscosity is 10... 4 The temperature at dPas.

[0020] Glass transition temperature T g The temperature can be at least 500°C or at least 550°C. In an advantageous embodiment, the transition temperature T... g The temperature should not exceed 800°C, preferably at most 780°C, or in some variations at most 750°C. If the transition temperature T... g If the temperature is too high, the glass cannot be used for conventional passivation processes. According to ISO 7884-8:1987, "T..." g "To change the temperature."

[0021] The softening temperature and / or processing temperature can be determined using glass viscosity determination methods known to those skilled in the art, such as according to ISO 7884-2:1987-12.

[0022] Preferably, the glass exhibits an etching rate of at most 1.0 µm / min in 5% HF at room temperature (RT), i.e., about 20°C. Alternatively or additionally, the glass exhibits a weight loss of less than 3% after 10 minutes in 65% HNO3 at 85°C. Excessively high etching rates or weight losses can negatively impact the passivation layer because the passivated element may be exposed to HNO3 and / or HF for cleaning purposes during the fabrication of the semiconductor device. A preferred glass exhibits an etching rate of at most or less than 0.9 µm / min or at most or less than 0.8 µm / min in 5% HF at room temperature. The etching rate in 5% HF at room temperature can be at least 0.1 µm / min or at least 0.2 µm / min. In an advantageous embodiment, the weight loss after 10 minutes in 65% HNO3 at 85°C is less than 2%. The glass, when exposed to 65% HNO3 at 85°C for 10 minutes, exhibits a weight loss rate greater than 0.5%. This demonstrates that the glass used according to the present invention can possess an etching rate or weight loss rate comparable to leaded glass or solder in terms of chemical resistance. Therefore, the glass described within the scope of this invention can replace lead-passivated glass or solder.

[0023] The etching rate of massive glass was determined at room temperature in 5% HF. If powdered samples were to be tested, the powder was first melted (e.g., within the temperature range between the glass's softening and processing temperatures) into a molten form and poured into a mold to obtain a massive sample. Sample preparation (cutting, grinding, polishing, cleaning, etc.) was performed according to standard DIN 12116. The sample was then exposed to an aqueous solution of acid (5% HF) at room temperature for 10 minutes. After cleaning and drying in an oven according to standard DIN 12116, the amount of etching removal was determined. The amount of etching removal was determined based on the sample's weight loss (i.e., the weight difference before and after acid treatment) and converted to sample surface area in a known manner. For each type of glass, the etching rate of three samples was measured, and the average value was calculated.

[0024] The weight loss at 85°C in 65% HNO3 was also determined for bulk glass. If the powdered sample was to be tested, the powder was first melted (e.g., within the temperature range between the glass's softening temperature and processing temperature) into a melt and poured into a mold to obtain a bulk sample. Sample preparation (cutting, grinding, polishing, cleaning, etc.) was completed according to standard DIN 12116. The sample was then exposed to 65% HNO3 at 85°C for 10 minutes. After cleaning and drying in an oven according to standard DIN 12116, the weight loss (the difference in sample weight before and after acid treatment) was measured. For each type of glass, the weight loss of three samples was measured, and the average value was calculated.

[0025] The compositional characteristics discussed in this article contribute to the excellent properties of the glass. Studies have found that particularly favorable properties can be obtained, especially by optimizing the contents of SiO2, Al2O3, B2O3, BaO, and RO. Studies have also found that one or more of the following measures (e.g., proportionally fine-tuning the amount of specific components to meet specific sums or specific differences) help improve the desired excellent properties in terms of softening temperature and chemical resistance.

[0026] The glass used in this invention contains SiO2 at a content of 45.0% to 58.0% by weight. This content must not be lower than the minimum of 45.0% by weight, otherwise the acid resistance, particularly the resistance to HF and HNO3, will deteriorate; the content must not exceed the upper limit of 58.0% by weight, because as the SiO2 content increases, the softening temperature rises, thus increasing the firing temperature required to form the passivation layer. In an advantageous embodiment, the SiO2 content of the glass is at least 45.5% by weight or at least 46.0% by weight. In an advantageous embodiment, this content may optionally be up to 57.5% by weight, particularly up to 57.0% by weight, or up to 56.5% by weight, or up to 56.0% by weight, or up to 55.5% by weight.

[0027] The glass used in this invention contains Al2O3 at a content of 5.0% to 15.0% by weight. This content must not be lower than the minimum of 5.0% by weight, otherwise acid resistance, particularly resistance to HF and HNO3, will deteriorate; this content must not exceed the upper limit of 15.0% by weight, otherwise the softening temperature of the glass and the temperature required for the passivation layer firing will increase. Furthermore, when the Al2O3 content is too high, i.e., >15.0% by weight, it has a negative impact on acid resistance. In an advantageous embodiment, the glass contains at least 6.0% by weight, at least 7.0% by weight, at least 8.0% by weight, or at least 9.0% by weight of Al2O3. Advantageously, this content can be limited to a maximum of 14.5% by weight, and for some advantageous variations, the content can be limited to a maximum of 14.0% by weight, a maximum of 13.0% by weight, or a maximum of 12.0% by weight.

[0028] In an advantageous embodiment, the total content of SiO2 and Al2O3 (SiO2 + Al2O3) can be from 50.0% to 72.0% by weight. Both SiO2 and Al2O3 are components that can improve the chemical resistance of glass, but SiO2 has a greater impact. If the proportion of Al2O3 in this total is too high, the acid resistance decreases; therefore, as described above, the Al2O3 content is limited. This total must not exceed the upper limit of 72.0% by weight to advantageously obtain glass with a lower softening temperature. An advantageous upper limit for the total may also be at most 71.0% by weight or at most 70.0% by weight. To improve the acid resistance of the glass, the total content of SiO2 + Al2O3 is at least 50.0% by weight. Advantageously, this total can be at least 52.0% by weight or at least 54.0% by weight.

[0029] The glass used in this invention contains B2O3 at a content of 4.5% to 16.0% by weight. B2O3 is a glass component that can lower the softening temperature and processing temperature of the glass, thereby reducing the firing temperature required during passivation; therefore, its content in the glass is at least 4.5% by weight. This content must not exceed the upper limit of 16.0% by weight, as a high proportion will negatively affect the chemical resistance of the glass. Higher contents of boron or boron compounds are considered to have an environmental impact, and therefore the release of B2O3 from the glass should be minimized. In an advantageous embodiment, the B2O3 content of the glass is at least 5.0% by weight, at least 7.0% by weight, at least 8.0% by weight, at least 9.0% by weight, or at least 10.0% by weight. In an advantageous embodiment, the content is optionally at most 15.5% by weight or at most 15.0% by weight.

[0030] The glass used in this invention contains RO at a content of 15.0% to 32.0% by weight, where RO represents the sum of alkaline earth metal oxides MgO, CaO, BaO, and SrO. Alkaline earth metal oxides can lower the softening temperature of the glass, which is why the glass contains at least 15.0% by weight of RO. The upper limit of 32.0% by weight must not be exceeded, otherwise the chemical resistance of the glass will deteriorate, and there is a risk of crystallization (devitrification) in the glass. In an advantageous embodiment, the RO content in the glass is at least 16.0% by weight, at least 17.0% by weight, at least 18.0% by weight, at least 19.0% by weight, or at least 20.0% by weight. For some advantageous variations, the RO content can also be greater than 20.0% by weight, preferably at least 21.0% by weight, or at least 22.0% by weight; advantageously, this content can be limited to a maximum of 30.0% by weight, a maximum of 28.0% by weight, or a maximum of 27.0% by weight. An advantageous RO content range can also be from 20.0% by weight to 32.0% by weight.

[0031] In an advantageous embodiment, the total content of B2O3 and RO (B2O3+RO) can be from 26.0% to 48.0% by weight. Both B2O3 and RO are components that help lower the glass softening temperature, therefore the total should be at least 26.0% by weight; advantageously, the lower limit of this total can be at least 27.0% by weight, at least 28.0% by weight, at least 29.0% by weight, or at least 30.0% by weight in some variations. The total content of B2O3+RO can be at most 48.0% by weight; advantageously, this content can be at most 46.0% by weight or at most 44.0% by weight.

[0032] The glass used in the present invention contains BaO in a content of 8.0% to 27.0% by weight, meaning that the glass necessarily contains BaO as an alkaline earth metal oxide. The content of BaO in the glass is at least 8.0% by weight because this component is more suitable for achieving the required low softening temperature in passivating glass than other alkaline earth metal oxides (i.e., CaO and / or MgO and / or SrO). If the proportion of BaO is too high, the coefficient of thermal expansion of the glass will increase excessively, therefore its content must not exceed the upper limit of 27.0% by weight. In an advantageous embodiment, the BaO content of the glass is at least 9.0% by weight, at least 10.0% by weight, at least 11.0% by weight, or at least 12.0% by weight; advantageously, its content can be limited to a maximum of 26.5% by weight, a maximum of 26.0% by weight, or a maximum of 25.5% by weight.

[0033] In an advantageous embodiment, the glass may contain MgO in a content of 0.0 wt% to 12.0 wt%. When the glass is required to contain MgO, it may advantageously contain at least 0.1 wt% or at least 0.2 wt% MgO. In an advantageous embodiment, the MgO content is limited to a maximum of 12.0 wt%, a maximum of 11.0 wt%, a maximum of 10.0 wt%, a maximum of 8.0 wt%, a maximum of 6.0 wt%, a maximum of 4.0 wt%, or a maximum of 2.0 wt%. In some advantageous variations, the MgO content may also be a maximum of 1.5 wt%, a maximum of 1.0 wt%, or a maximum of 0.5 wt%. In an advantageous embodiment, the glass is MgO-free. It may be advantageous to reduce the MgO content or omit MgO entirely to prevent crystal formation in the glass.

[0034] In an advantageous embodiment, the glass may contain CaO in a content of 0.0% to 12.0% by weight. When the glass is required to contain CaO, it may advantageously contain at least 0.1% or at least 0.2% by weight of CaO. In an advantageous embodiment, the CaO content is limited to a maximum of 12.0% by weight, a maximum of 11.0% by weight, a maximum of 10.0% by weight, a maximum of 8.0% by weight, a maximum of 6.0% by weight, a maximum or less than 5.0% by weight, a maximum of 4.0% by weight, or a maximum of 2.0% by weight. For some advantageous variations, the CaO content may also be a maximum of 1.5% by weight, a maximum of 1.0% by weight, or a maximum of 0.5% by weight. In an advantageous embodiment, the glass does not contain CaO. It may be advantageous to reduce the CaO content or omit CaO entirely to prevent crystal formation in the glass.

[0035] In an advantageous embodiment, the glass may contain SrO in a content of 0.0 wt% to 8.0 wt%. When the glass should contain SrO, it may advantageously contain at least 0.1 wt% or at least 0.2 wt% SrO. In an advantageous embodiment, the SrO content is limited to a maximum of 8.0 wt%, a maximum of 6.0 wt%, a maximum of 4.0 wt%, or a maximum of 2.0 wt%. For some advantageous variations, the SrO content may also be a maximum of 1.5 wt%, a maximum of 1.0 wt%, or a maximum of 0.5 wt%. In an advantageous embodiment, the glass does not contain SrO. It may be advantageous to reduce the SrO content or omit SrO entirely to prevent crystal formation in the glass.

[0036] In an advantageous embodiment, the glass contains only a single alkaline earth metal oxide, namely, only BaO. In this variation, the total RO content is entirely formed by BaO. In this case, the total RO content is limited to 27.0% by weight. In this variation, the BaO content is from 15.0% by weight to 27.0% by weight.

[0037] In other advantageous embodiments, in addition to BaO, the glass may contain one or more other alkaline earth metal oxides. These other alkaline earth metal oxides are collectively referred to as R'O. R'O is the sum of MgO + CaO + SrO. When the glass contains at least one other alkaline earth metal oxide besides BaO, R'O must be selected such that the sum of all alkaline earth metal oxides RO (i.e., BaO + MgO + CaO + SrO) falls within the scope of this invention.

[0038] The inventors recognized that when the proportion of BaO in the total RO is highest, i.e., the BaO content in the glass is higher than that of R'O (i.e., MgO + CaO + SrO), the softening temperature of the glass can be advantageously and specifically set to a lower value. In an advantageous embodiment, the difference in weight percentage between BaO and the total of the other alkaline earth metal oxides MgO, CaO, and SrO, i.e., the difference between BaO and (MgO + CaO + SrO) (also referred to as BaO-R'O), can be from 1.0 wt% to 27.0 wt%. Advantageously, the lower limit of the BaO-R'O difference can be at least 2.0 wt%, at least 3.0 wt%, and at least 5.0 wt%. As mentioned above, it may be advantageous for the glass to have a BaO content much higher than that of R'O, preferably even containing only BaO and no R'O.

[0039] In an advantageous variation, the glass contains at least two alkaline earth metal oxides, namely, it must contain BaO, and at least one other alkaline earth metal oxide (R'O) selected from MgO, CaO and SrO.

[0040] In another advantageous variation, the glass contains at least three alkaline earth metal oxides, namely, it must contain BaO, and at least two other alkaline earth metal oxides (R'O) selected from MgO, CaO and SrO.

[0041] In an advantageous variation, when the glass contains exactly two alkaline earth metal oxides, namely BaO and a single other alkaline earth metal oxide (MgO, CaO, or SrO), the content of this other alkaline earth metal oxide must be selected based on the BaO content so that the total R'O falls within the range of 15.0 wt% to 32.0 wt%. Furthermore, regarding the softening temperature, it is advantageous that the BaO-R'O difference falls within the range of 1.0 wt% to 27.0 wt%. For example, the glass may contain, for instance, 25.0 wt% BaO and 7.0 wt% R'O, thus the BaO-R'O difference here is 18.0 wt%.

[0042] In an advantageous variation, when the glass contains exactly three alkaline earth metal oxides, namely BaO and two other alkaline earth metal oxides (MgO+CaO or MgO+SrO or CaO+SrO), the total amount of the two other alkaline earth metal oxides R'O must be selected based on the BaO content so that the total R'O falls within the range of 15.0 wt% to 32.0 wt%. Furthermore, regarding the softening temperature, it is advantageous that the BaO-R'O difference falls within the range of 1.0 wt% to 27.0 wt%. For example, the glass may contain, for instance, 20.0 wt% BaO and 12.0 wt% R'O, thus the BaO-R'O difference here is 8.0 wt%.

[0043] In an advantageous variation, when the glass contains all four alkaline earth metal oxides, namely BaO and three additional alkaline earth metal oxides (MgO + CaO + SrO), the sum of these additional alkaline earth metal oxides R'O is selected based on the BaO content so that the total R'O falls within the range of 15.0 wt% to 32.0 wt%. Furthermore, regarding the softening temperature, it is advantageous that the difference between BaO and R'O falls within the range of 1.0 wt% to 27.0 wt%. For example, the glass may contain, for instance, 17.0 wt% BaO and 15.0 wt% R'O, thus the BaO-R'O difference is 2.0 wt%.

[0044] The inventors have recognized that glasses within the above composition range can be advantageously used as passivating glasses when the following condition is met: (RO+B2O3) / (SiO2+Al2O3) is at least 0.39. That is, the sum of B2O3+RO and the sum of SiO2+Al2O3 are calculated based on the weight percentage content of the above components, and the ratio of the two is taken. Glasses satisfying this ratio achieve an excellent balance between acid resistance and a lower melting temperature. In an advantageous embodiment, the (RO+B2O3) / (SiO2+Al2O3) ratio is at least 0.40, preferably at least 0.45, preferably at least 0.50, for a particularly advantageous variant at least 0.55, more preferably at least 0.60 or at least 0.65. For the ratio of (RO+B2O3) / (SiO2+Al2O3), an advantageous upper limit can be less than 1.00, particularly at most 0.96, to obtain a glass with excellent acid resistance and a low melting temperature, i.e., achieving the desired balance between the two properties of the glass. In an advantageous embodiment, this upper limit can be at most 0.95, preferably at most 0.90. In some advantageous variations, the upper limit can be at most 0.85 or at most 0.80.

[0045] In an advantageous embodiment, the weight percentage difference between BaO and B2O3 (BaO-B2O3) can be from 2.0 wt% to 12.0 wt%; given that both components have a positive effect on reducing the softening temperature, the BaO content used in the glass is higher than the B2O3 content, thereby improving chemical resistance. Therefore, this difference should be at least 2.0 wt%. For some advantageous variations, the lower limit of this advantageous difference can be at least 4.0 wt%, preferably at least 6.0 wt% or at least 8.0 wt%. The upper limit of this advantageous difference is 12.0 wt%.

[0046] For some variant schemes, it is advantageous that the BaO / SiO2 ratio is greater than 0.4, and / or the BaO / Al2O3 ratio is greater than 2.2.

[0047] In one embodiment, the glass may contain ZnO in a content of 0.0 wt% to a maximum of 5.0 wt%. Because this component negatively affects the acid resistance of the glass, its content should be limited to a maximum of 5.0 wt%. An advantageous upper limit may also be a maximum of 3.0 wt% or a maximum of 2.0 wt%. When the glass should contain ZnO to, for example, specifically reduce the softening temperature, an advantageous lower limit may be at least 0.1 wt%, at least 0.2 wt%, or at least 0.5 wt%. A preferred variant of the glass may be ZnO-free.

[0048] In an advantageous embodiment, the glass may contain at least one of the following components: 0.0 wt% to 4.0 wt% of ZrO2 and / or 0.0 wt% to 6.0 wt% of TiO2 and / or 0.0 wt% to 2.0 wt% of Ta2O5 and / or 0.0 wt% to 2.0 wt% of Nb2O5. If the glass is to contain one or more of the above components, then in each case, a suitable lower limit may be 0.1 wt% or 0.2 wt%. The components ZrO2 and / or TiO2 can improve chemical resistance; however, they may negatively affect the softening temperature of the glass and increase the risk of undesirable crystallization. An advantageous upper limit for ZrO2 may be up to 3.0 wt%, up to 2.0 wt%, or up to 1.0 wt%. An advantageous upper limit for TiO2 may be up to 5.0 wt%, and for some variations up to 4.0 wt%, up to 3.0 wt%, up to 2.0 wt%, or up to 1.0 wt%. The components Ta2O5 and Nb2O5 can also improve the chemical resistance of the glass, wherein the advantageous upper limit for both components can be 1.0% by weight. An advantageous improvement to the glass may be the absence of ZrO2 and / or TiO2 and / or Ta2O5 and / or Nb2O5.

[0049] To reduce costs and avoid defects in the formed passivation layer, in an advantageous embodiment, the glass contains up to 2.0 wt% or up to 1.0 wt% Bi₂O₃. Particularly preferably, the glass is Bi₂O₃-free.

[0050] According to a preferred embodiment, the glass used in this invention is low-alkali, more preferably alkali-free, because alkali metal ions, especially at high temperatures, diffuse out of the glass, for example, into semiconductor devices (e.g., chips), thereby impairing the functionality of the semiconductor devices (e.g., diodes). In the context of this invention, low-alkali means that the total amount of alkali metal oxides in the glass (i.e., Li₂O + Na₂O + K₂O + Cs₂O + Rb₂O) is at most 3% by weight, preferably at most 2% by weight, preferably at most 1% by weight, preferably at most or less than 0.5% by weight, more preferably at most or less than 0.1% by weight. If the glass contains only a single alkali metal oxide, the upper limits for each alkali metal oxide described above can be applied. If it contains two or more alkali metal oxides, the upper limits for any combination described above can be applied accordingly. The content of alkali metal oxides must be limited to achieve the desired high breakdown strength. A particularly preferred variant of the glass is free of alkalis except for common impurities, i.e., free of alkali metal oxides Li₂O and / or Na₂O and / or K₂O, and especially free of Li₂O, Na₂O, K₂O, Cs₂O and / or Rb₂O.

[0051] According to a preferred embodiment, the glass used in this invention is free of Cu and / or Fe and / or Cd and / or other colored transition metals or their oxides.

[0052] According to one embodiment, the glass comprises at least 94.0% by weight, preferably at least 95% by weight, and in some advantageous variations at least 97% by weight of the components SiO2, Al2O3, B2O3, and RO.

[0053] According to an advantageous variation, the glass does not contain any components not mentioned in this disclosure.

[0054] In the context of this invention, the terms "Pb-free," "lead-free," "alkali-free," or broadly "free of a certain component x" should be understood to mean that the substance or its oxide is not intentionally added to the passivated glass as a component, but exists at most in trace or minute residual form, i.e., at most as an impurity in the glass. For lead, the Pb content is less than 1000 ppm to meet the current RoHS directive. Advantageously, the Pb content can be less than 500 ppm, preferably less than 100 ppm. For example, for Li₂O, Na₂O, K₂O, Cs₂O, Rb₂O, Cu, Fe, Cd, and / or other components "free" as described above, the content of each component can be less than 100 ppm, preferably less than 50 ppm.

[0055] In an advantageous improvement, the glass may contain the following components by weight percent of oxides:

[0056] In an advantageous improvement, the glass, alone or in any combination, comprises the following components by weight percent of oxides:

[0057] In one embodiment, the average coefficient of thermal expansion of the glass used is at most or less than 5.5 within a temperature range of 20°C to 300°C. * 10 -6 K -1(i.e., at most 5.5 ppm / K) or at most 5.0 ppm / K, or in some variations at most 4.8 ppm / K. In particular, the coefficient of thermal expansion can be in the range of 3.5 ppm / K to 5.5 ppm / K. The values ​​given above are the average linear coefficient of thermal expansion in the temperature range of 20°C to 300°C, also known as "CTE," which is determined according to the standard DIN ISO 7991:1987. In other words, in an advantageous embodiment, the glass has an average linear coefficient of thermal expansion of 3.5 ppm / K to 5.5 ppm / K in the temperature range of 20°C to 300°C. It has been demonstrated that glass with this coefficient of thermal expansion can adequately accommodate the expansion of semiconductor materials (e.g., silicon) to, for example, prevent cracking of the passivation layer.

[0058] Glass used for passivating electronic components can be used in the passivation process in powder form (i.e., in powder form). For this purpose, glass with the desired composition is prepared using a melting technique, and then pulverized and ground using a known grinding method. The glass exists in the form of glass powder. Studies have found that the choice of particle size and particle size distribution affects the quality of the passivation layer for electronic components. Furthermore, the choice of particle size and its distribution also affects acid resistance and the formation of gaps.

[0059] In an advantageous embodiment, the average particle size d of the glass powder 50 The particle size can be from 1.0µm to 12.0µm, particularly from 1.5µm to 5.0µm or from 2.0µm to 3.0µm. It has been proven that this particle size, preferably combined with the following distribution range, can achieve excellent acid resistance during the passivation process.

[0060] In an advantageous embodiment, the particle size distribution span of the glass powder (d) 90 -d 10 ) / d 50 The value can be at least 1.00, and particularly at least 1.80. A larger distribution span indicates a better packing density, thus reducing the tendency for the glass or passivated glass to form gaps between the layer and the semiconductor element during heat treatment when forming the passivation layer. However, the distribution span should not be too large, otherwise it may reduce acid resistance. This distribution span can be limited to a maximum of 6.00, a maximum of 4.50, or a maximum of 3.50, and particularly a maximum of 3.00.

[0061] The particle size and particle size distribution provided in this specification can be determined using dynamic light scattering methods, such as those according to standard ISO 13320:2009. Evaluation can also be performed using the Fraunhofer method, and the measured values ​​can be expressed as volume distribution.

[0062] In the application of this invention, the glass can be used alone or in any combination with inorganic additives (also referred to as "fillers"), preferably in powder form, crystalline additives. In one embodiment, specifications regarding particle size and / or particle size distribution also apply to the glass composition and filler composition. Fillers can be, for example, selected from the group consisting of: ZrO2, willemit, cordierite, fused silica, high-quartz mixed crystals, β-lithium nepheline (Li2Al2Si2O8), aluminum titanate (Al2TiO5), and ZrW2O8. The use of fillers facilitates adapting the thermal expansion of the passivation layer to the thermal expansion of the electronic component components; therefore, fillers with a negative coefficient of thermal expansion are advantageous.

[0063] If glass (i.e., passivated glass) and filler are used together in the passivation process, the combination of glass and filler can also be called "fusion solder".

[0064] The filler content in the fusion solder can be at least 1.0 vol%, at least 2.0 vol%, at least 3.0 vol%, at least 4.0 vol%, or at least 5.0 vol%. In one embodiment, the filler content can be at most 25.0 vol%, at most 20.0 vol%, at most 17.5 vol%, or at most 15.0 vol%.

[0065] Specifically, the proportions of components other than glass and crystallizing additive (kristallinen Zusatz) can be limited to a maximum of 10.0% by volume, a maximum of 5.0% by volume, a maximum of 2.5% by volume, a maximum of 1.0% by volume, or a maximum of 0.5% by volume. In one embodiment, the proportion of glass in the fusion solder is at least 80.0% by volume. In another embodiment, the proportion of glass in the fusion solder is at least 85.0% by volume or at least 87.5% by volume. This proportion is optionally up to 90% by volume. The fusion solder may consist of glass and crystallizing additive.

[0066] Fusion solder can be in powder form. The particle size and particle size distribution of the glass powders described above can also be advantageously applied to fusion solders. To avoid repetition, please refer to the description above.

[0067] In one advantageous embodiment, the filler content in the fusion solder can be from 1.0% to 25.0% by volume, and the glass content can be from 99.0% to 75% by volume.

[0068] On the other hand, the present invention relates to the use of glass in passivating electronic components, particularly semiconductor components, wherein the glass contains SiO2, Al2O3, B2O3, and BaO, and contains no Pb except as an impurity, and the ratio of (RO+B2O3) / (SiO2+Al2O3) is at least 0.39, wherein the sum and ratio are calculated based on the content of each component (in weight % of oxides), and RO is the sum of BaO+MgO+CaO+SrO. Preferably, the softening temperature of the glass is up to 930°C, and / or the etching rate is up to 1.0 µm / min at room temperature in a 5% HF solution.

[0069] Preferably, the difference between BaO and B2O3 is at least 2.0% by weight. Advantageously, the glass may comprise the following components by weight percent of oxides:

[0070] The advantageous composition, advantageous chemical and physical properties of the glass used, as well as the possible particle size and particle size distribution of the glass powder or fusion solder powder (composed of glass and filler) have been described above in conjunction with the first aspect of the invention; the disclosure of which is incorporated herein in its entirety into the description of other aspects of the invention; to avoid repetition, please refer to the relevant description above.

[0071] method In another aspect, the present invention relates to a method for manufacturing glass-passivated electronic components, comprising the following steps: Provide electronic components or substrates; Processing powders containing or composed of glass into formulations, particularly slurries or suspensions; The formulation is applied to an electronic component or substrate in the form of a layer; The electronic component or substrate to which the formulation is applied is subjected to heat treatment to melt the glass and generate a passivation layer. The method is characterized in that it uses glass according to the uses of the present invention as described above.

[0072] The advantageous composition, advantageous chemical and physical properties of the glass used, as well as the possible particle size and particle size distribution of the glass powder or fusion solder powder (composed of glass and filler) have been described in detail in the description of the first aspect of the invention above; the disclosure of which is incorporated herein in its entirety into the method of the invention; to avoid repetition, please refer to the relevant description above.

[0073] An electronic component or substrate is provided to be passivated. The electronic component may advantageously be selected from diodes, variable resistors, thyristors, transistors, and power transistors (e.g., IGBTs). However, the term "electronic component" should be interpreted broadly to also encompass underlying intermediate products based on semiconductor materials, particularly substrates, such as wafers (e.g., silicon wafers) or other substrates. The electronic component may comprise materials such as silicon, SiC, SiN, GaAs, GaN, AlN, and / or mixtures thereof, particularly wide-bandgap semiconductors.

[0074] Glass with the desired composition is ground into a fine powder, wherein the average particle size d of the glass is... 50 The thickness can preferably be from 1.0µm to 12.0µm, particularly from 1.5µm to 5.0µm or from 2.0µm to 3.0µm.

[0075] An formulation, particularly a solid-liquid mixture, more particularly a slurry or suspension, is prepared from a powder comprising glass and other additives, or from a powder composed of glass and other additives, wherein the formulation may contain additional additives, such as dispersants, organic binders, solvents, etc., depending on the specific requirements of the passivation layer. The powder used may consist solely of glass, or, as described in the first aspect of the invention, may be a mixture of glass and fillers.

[0076] The formulation is applied to the provided electronic component, preferably in the form of a coating, wherein known coating methods, particularly liquid phase coating methods, can be employed. For example, the formulation can be applied by spin coating, spray coating, dip coating, casting, brush coating, screen printing, pad printing, inkjet printing, offset printing, roll coating, doctor blade coating, or other methods known to those skilled in the art. Doctor blade coating or screen printing is particularly advantageous. The coating can be applied to the electronic component, or to the provided substrate in the case of substrate passivation (i.e., a glass coating on the substrate (particularly the wafer) before separation of the electronic component). Layer formation may also include electrophoresis. The formulation should preferably wet the bonding ligand, such as the substrate, metal leads, and electrodes, to avoid cavities during firing and to prevent peeling.

[0077] Subsequently, the electronic component or substrate to which the formulation is applied is subjected to heat treatment (also known as "firing"), which melts the glass to form a passivation layer. In an advantageous embodiment, the heat treatment temperature ranges from 600°C to 930°C, preferably from 640°C to 930°C. In an advantageous variation, the firing temperature can be from 700°C to 900°C or from 700°C to 880°C. These temperatures can have a positive effect on chemical resistance because the high temperature makes the melt more homogeneous and eliminates grain boundaries in the powder, thereby reducing the surface area exposed to acids.

[0078] Passivated electronic components According to another aspect of the invention, the invention also includes an electronic element, particularly a semiconductor element, comprising at least one passivation layer, said passivation layer comprising or composed of glass according to the uses of the invention described above.

[0079] The advantageous composition, advantageous chemical and physical properties of the glass used, as well as the possible particle size and particle size distribution of the glass powder or the powder of the fusion solder comprising glass and filler, have been described above in conjunction with the first aspect of the invention; furthermore, the manufacturing method has also been described above; the disclosure of which is incorporated herein in its entirety into the description of the passivated electronic components of the invention; to avoid repetition, please refer to the relevant description above.

[0080] Advantageously, electronic components (especially semiconductor components) can be selected from: diodes, variable resistors, thyristors, transistors, power transistors, such as insulated-gate bipolar transistors (IGBTs). The term "electronic component" can also cover underlying intermediate products based on semiconductor materials, especially substrates or wafers. The materials of electronic components or substrates can include, for example, silicon, SiC, SiN, GaAs, GaN, AlN and / or mixtures thereof, i.e., particularly wide-bandgap semiconductors.

[0081] Advantageously, the thickness of the passivation layer can be from 3 µm to 100 µm. In some advantageous variations, the thickness can be from 10 µm to 100 µm, particularly from 20 µm to 80 µm or from 20 µm to 50 µm.

[0082] It should be understood that the present invention covers multiple aspects, and without departing from the scope of the present invention, the various features of the present invention described in the context can be used not only in the specified combinations, but also in other combinations. Detailed Implementation

[0083] Glass is molten in a heated Pt crucible at temperatures up to 1650°C using conventional raw materials (which are essentially lead-free and alkali-free, except for unavoidable impurities). The melt is then geläutert-treated at this temperature for 1 hour, stirred until homogeneous, and then cast into ingots.

[0084] To prepare glass powder, the melt can be passed through a water-cooled metal roller (wassergekühlteMetallwalzen), and the resulting glass ribbon (Ribbon) can then be ground.

[0085] In addition to the composition, the physical / chemical parameters and properties of the examples and control examples were also measured.

[0086] As mentioned above, the etching rate was measured in a 5% HF solution at room temperature for 10 minutes and the weight loss was measured in a 65% HNO3 solution at 85°C for 10 minutes.

[0087] If the etching rate (the measured value is given in parentheses) is at most 1.0 µm / min, the tolerance to 5% HF is assessed as “excellent”. In contrast, if the etching rate is higher, i.e., >1.0 µm / min, the etching rate is considered “poor”.

[0088] If the weight loss is less than 3% based on the weight before and after acid treatment, and there is no visible coating on the sample surface, then the resistance to HNO3 is assessed as "excellent." Conversely, if the weight loss is at least 3%, the resistance to HNO3 is assessed as "poor," regardless of whether a coating has formed. Even if the weight loss is less than 3%, if no visible coating has formed on the sample surface, the resistance to HNO3 is still considered "poor." If the sample surface is noticeably cloudy, it indicates the presence of a coating. This cloudiness is caused by the chemical reaction between the acid and the glass, which is an undesirable phenomenon.

[0089] Table 1 lists seven embodiments of the present invention, while Table 2 lists comparative examples. In all embodiments, the (RO+B2O3) / (SiO2+Al2O3) ratio is at least 0.39, exhibiting excellent resistance to the tested acids, comparable to lead-passivated glass (see Table 2, Comparative Example C1). In contrast, passivated glasses currently made from Zn-B-Si glass, which can be used as alternatives to lead-containing glasses, exhibit significantly poorer acid resistance (see Table 2, Comparative Example C3).

[0090] Although the softening temperature of the glass of the present invention (Examples 1-7) is higher than that of lead glass (see Comparative Example C1), its softening temperature is still significantly lower than 930°C, and in Examples 1-6 it is even lower than 880°C, so that it can be used for passivation processes at suitable firing temperatures.

[0091] Comparative Examples C2, C4 through C7 also demonstrate that glasses outside the scope of the compositions claimed in this disclosure are inferior to lead-passivated glasses (which can be used as a reference standard) in terms of acid resistance and / or softening temperature. According to the composition of Comparative Example C5, it cannot even be melted into any glass; that is, the sample is non-meltable (ns).

[0092] Table 1: Examples (by weight %) Table 2: Control Examples (by weight %)

Claims

1. Uses of glass in passivating electronic components, particularly semiconductor components, wherein, The glass contains no Pb except in the form of impurities, and comprises the following components by weight percent of oxides: Wherein, RO is the sum of BaO + MgO + CaO + SrO, and the ratio of (RO + B₂O₃) / (SiO₂ + Al₂O₃) is at least 0.39, and The difference between BaO and B2O3 is at least 2.0 wt%.

2. The use according to claim 1, wherein, The sum of RO and B2O3 is 26.0 to 48.0% by weight, and / or the sum of SiO2 and Al2O3 is 50.0 to 72.0% by weight.

3. The use according to claim 1 or 2, wherein, The difference between BaO and B2O3 is 2.0 to 12.0% by weight, and / or the difference between BaO and (MgO+CaO+SrO) is 1.0 to 27.0% by weight.

4. The use according to any one of the preceding claims, wherein, The BaO content is at least 11.0% by weight, and / or the ZnO content is at most or less than 5.0% by weight.

5. The use according to any one of the preceding claims, wherein, The glass, individually or in any combination, comprises the following components by weight percent of oxides: 。 6. The use according to any one of the preceding claims, wherein, The glass has at least one of the following characteristics: - At room temperature in 5% HF, the etching rate is at most 1.0 µm / min. - The softening temperature Ew is up to 930°C. - The average linear coefficient of thermal expansion is 3.5 to 5.5 ppm / K in the temperature range of 20°C to 300°C.

7. The use according to any one of the preceding claims, wherein, The glass is used in powder form, wherein the powder advantageously has at least one of the following characteristics: - The average particle size d50 is 1.0µm to 12.0µm, particularly 1.5µm to 5.0µm. - The span of the particle size distribution (d90-d10) / d50 is at least 1.00, particularly at least 1.80 and / or at most 6.00, particularly at most 4.

50.

8. A method for manufacturing electronic components using glass passivation, comprising the following steps: - Provide electronic components; - Processing powders containing or composed of glass into formulations, particularly slurries or suspensions; - The formulation is applied to the electronic component in the form of a layer; - The electronic component to which the formulation is applied is subjected to heat treatment, causing the glass to melt and form a passivation layer. The glass according to any one of claims 1 to 7 is used in the method.

9. The method according to claim 8, wherein, The heat treatment is performed in a temperature range of 600°C to 930°C.

10. An electronic component, particularly a semiconductor component, preferably a wafer, diode, thyristor, variable resistor, transistor, IGBT, comprising at least one passivation layer, said at least one passivation layer comprising or composed of glass according to any one of claims 1 to 7.

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