LTCC substrate with low thermal expansion coefficient, and spatial converter using the same

Abstract

The present invention relates to an LTCC ceramic substrate, a substrate for an STF (space transformer) containing the same, and a probe card. The LTCC ceramic substrate is made of cordierite (Mg2Al4Si5O 18 The material comprises ) and alumina (Al2O3), and in X-ray diffraction analysis by Cu Kα irradiation, the ratio I2 / I1 of the peak I2 derived from cordierite to the peak I1 derived from alumina may be approximately 0.14 or more, or approximately 0.15 or more.

Description

Technical Field

[0001] The present invention relates to a ceramic structure, and more particularly, to a low-temperature co-fired ceramic substrate having a low coefficient of thermal expansion (Low CTE) and a space transformer using the same.

Background Art

[0002] Generally, a probe card is used for electrical defect inspection of a wafer on which a plurality of semiconductor elements such as memories are formed. The probe card has a composite ceramic substrate called a space transformer (STF), which is an interposer arranged between a large number of probes and a printed circuit board connected to a test device.

[0003] In the electrical defect inspection using the space transformer (STF), the probe card is electrically connected to the tester, and at the same time, a large number of probes are brought into contact with the connection terminals of the semiconductor element [hereinafter referred to as Device Under Test (DUT)]. Then, by inputting and outputting a power supply and various signals necessary for the test between the tester and the semiconductor element, it is possible to determine defects and errors such as open circuits and short circuits (Open or Short) in the semiconductor element.

[0004] Recently, in order to increase the throughput of electrical inspection of the semiconductor element, it has been required to perform batch simultaneous inspection on the entire plurality of semiconductor elements at the wafer level to be inspected. Such inspection can involve not only normal temperature but also burn-in tests in a high-temperature environment and cold tests in a low-temperature environment. At this time, the space transformer also undergoes contraction and expansion accordingly.

[0005] Recently, with the trend towards larger wafer diameters and higher integration of semiconductor devices, the diameter of space transducers has increased, while the spacing between probes has also decreased. Generally, low-temperature co-fired ceramic (LTCC) substrates are used as the substrate for the space transducer (STF) to accommodate the miniaturization of semiconductor devices, allowing the use of low-resistance metal wiring such as copper and silver. In the case of typical LTCC substrates, the strength is relatively lower than that of high-temperature co-fired ceramic (HTCC), and the coefficient of thermal expansion is relatively higher than that of silicon wafers. In relation to this, various problems can occur when LTCC substrates are applied to space transducers (STF). For example, as the spacing between electrode pads of semiconductor devices decreases, the coefficient of thermal expansion of the LTCC substrate becomes larger than that of silicon wafers, which can degrade the contact reliability between the probe pins and the electrode pads of semiconductor devices during failure inspections such as burn-in tests and cold tests of semiconductor devices. Furthermore, during the burn-in and cold tests, if the spatial converter has a greater coefficient of thermal expansion than the silicon wafer, time is required to stabilize the temperature of the spatial converter for accurate testing, which hinders the increase in test processing capacity. In addition, repeated temperature changes cause thermal deformation of the LTCC substrate, which degrades its mechanical strength and lifespan.

[0006] Therefore, in order to enable high-reliability, high-speed testing despite testing in a wide range of temperature regions and repeated thermal deformation cycles, technologies are required that can improve the physical properties of LTCC substrates by improving the coefficient of thermal expansion. In particular, when the coefficient of thermal expansion of LTCC substrates is reduced, there is usually a problem of decreased strength, so it is important to ensure both a low coefficient of thermal expansion and strength. [Overview of the project] [Problems that the invention aims to solve]

[0007] The technical problem that this invention aims to solve is to provide a low thermal expansion coefficient ceramic substrate that has high strength while having low thermal expansion characteristics, and a space converter containing the same.

[0008] The problems that this invention aims to solve are not limited to those mentioned above, and other problems not mentioned can be clearly understood by those skilled in the art from the following description. [Means for solving the problem]

[0009] According to one embodiment of the present invention, cordierite (Mg2Al4Si5O 18 A ceramic substrate is provided which contains ) and alumina (Al2O3), and in X-ray diffraction analysis by Cu Kα irradiation, the ratio I2 / I1 of the peak I2 derived from the cordierite to the peak I1 derived from the alumina is approximately 0.14 or more or approximately 0.15 or more.

[0010] The ceramic substrate may further include anorthite and gahnite.

[0011] The ceramic substrate may include a matrix containing a glass component, a plurality of particulate first fillers dispersed within the matrix, and a plurality of particulate second fillers, wherein the first fillers may have a higher strength than the second fillers, and the second fillers may have a lower coefficient of thermal expansion than the first fillers.

[0012] The first filler may include at least one of alumina, mullite, and diopside.

[0013] The second filler may include at least one of cordierite, fused silica, willemite, eucryptite, zirconia, and celsian.

[0014] According to another embodiment of the present invention, an LTCC (low temperature co-fired ceramic) substrate for a space transformer (STF) is provided, comprising a fired ceramic sheet, wherein the fired ceramic sheet comprises a matrix layer containing a crystalline material and a glass material; a particulate first filler dispersed in the matrix layer; and a particulate second filler dispersed in the matrix layer, wherein the first filler has a higher strength than the second filler, and the second filler has a lower coefficient of thermal expansion than the first filler.

[0015] The aforementioned ceramic sheet is made of cordierite (Mg2Al4Si5O 18 It may contain ) and alumina (Al2O3), and in X-ray diffraction analysis by Cu Kα irradiation, the ratio I2 / I1 of the peak I2 derived from cordierite to the peak I1 derived from alumina may be about 0.14 or more or about 0.15 or more.

[0016] The first filler may include at least one of alumina, mullite, and diopside.

[0017] The second filler may include at least one of cordierite, fused silica, willemite, eucryptite, zirconia, and celsian.

[0018] The crystalline material may further include anorthite and garnite.

[0019] According to another embodiment of the present invention, a probe card including a STF (space transformer) applying the LTCC substrate described above is provided.

Effects of the Invention

[0020] According to each embodiment of the present invention, an LTCC substrate having high strength while having a low expansion rate is provided.

[0021] In addition, when the LTCC substrate according to the embodiment of the present invention is used as a STF (space transformer), a probe card having high strength and high reliability can be manufactured.

Brief Description of the Drawings

[0022] [Figure 1] It is a diagram for explaining the composition of a slurry for manufacturing an LTCC (low temperature co-fired ceramic) ceramic for an STF (space transformer) according to an embodiment of the present invention. [Figure 2] It is a schematic diagram for explaining the firing process of a ceramic sheet according to an embodiment of the present invention. [Figure 3] It is a schematic diagram for explaining the firing process of a green sheet in a method for manufacturing an LTCC ceramic according to an embodiment of the present invention. [Figure 4] It is a SEM (scanning electron microscope) photograph image showing the microstructure of an LTCC ceramic corresponding to Example 3 in Table 2. [Figure 5] It is a SEM photograph image showing the microstructure of an LTCC ceramic corresponding to Example 7 in Table 2. [Figure 6] It is a SEM photograph image showing the microstructure of an LTCC ceramic corresponding to Example 5 in Table 2. [Figure 7] It is a SEM photograph image showing the microstructure of an LTCC ceramic corresponding to Example 10 in Table 2. [Figure 8]This graph shows the ratio of peak I2 derived from the cordierite crystal phase to peak I1 derived from the alumina crystal phase (i.e., I2 / I1), flexural strength, and coefficient of thermal expansion (CTE) of LTCC ceramics according to each embodiment of the present invention. [Figure 9] This graph shows the results of X-ray diffraction analysis of an LTCC ceramic according to an embodiment of the present invention. [Figure 10] This graph shows the results of X-ray diffraction analysis of an LTCC ceramic according to an embodiment of the present invention. [Figure 11] This graph shows the results of X-ray diffraction analysis of an LTCC ceramic according to an embodiment of the present invention. [Figure 12] This graph shows the results of X-ray diffraction analysis of an LTCC ceramic according to an embodiment of the present invention. [Figure 13] This graph shows the results of X-ray diffraction analysis of an LTCC ceramic according to an embodiment of the present invention. [Figure 14] This graph shows the results of X-ray diffraction analysis of an LTCC ceramic according to an embodiment of the present invention. [Figure 15] This is a cross-sectional view illustrating an exemplary laminated substrate structure for manufacturing an LTCC substrate according to one embodiment of the present invention. [Figure 16] This is a cross-sectional view illustrating an exemplary laminated substrate structure for manufacturing an LTCC substrate according to another embodiment of the present invention. [Figure 17] This is a cross-sectional view illustrating an STF (space transformer) manufactured according to one embodiment of the present invention. [Figure 18] This is a cross-sectional view illustrating a probe card containing an STF manufactured according to one embodiment of the present invention. [Modes for carrying out the invention]

[0023] Hereinafter, each embodiment of the present invention will be described in detail with reference to the attached drawings.

[0024] The embodiments of the present invention described below are provided to further clarify the invention to those who are ordinaryly skilled in the art, and the scope of the invention is not limited by the embodiments below, and the embodiments below can be modified in various other forms.

[0025] The terms used herein are for the purpose of describing specific embodiments and are not intended to limit the invention. A singular term used herein may include multiple forms unless the context clearly indicates otherwise. Furthermore, the term “including” as used herein identifies the presence of the shapes, stages, figures, actions, members, elements, and / or groups thereof mentioned, and does not exclude the presence or addition of one or more other shapes, stages, figures, actions, members, elements, and / or groups thereof. Furthermore, the term “connected” as used herein is a concept that includes not only direct connection of each member, but also indirect connection through further interposition of other members between them.

[0026] Furthermore, when one component is described as being "on top of" another component in this specification, this includes not only cases where one component is in contact with another component, but also cases where another component exists between the two components. The terms "and / or" as used herein include any one or more combinations of the listed items. In addition, terms of degree used herein, such as "about" and "substantially," are used to mean a range of numerical values ​​or degrees or close to them, taking into account inherent manufacturing and material tolerances, and are used to prevent infringers from unfairly exploiting disclosures that refer to precise or absolute numerical values ​​provided to facilitate understanding of this application.

[0027] The embodiments of the present invention will be described in detail below with reference to the attached drawings. The sizes and thicknesses of the areas and parts shown in the attached drawings may be exaggerated to some extent for clarity and ease of explanation. The same reference numerals throughout the detailed description refer to the same components.

[0028] Figure 1 is a diagram illustrating the composition of a slurry for manufacturing an LTCC (low temperature co-fired ceramic) substrate for an STF (space transformer) according to one embodiment of the present invention.

[0029] Referring to Figure 1, the slurry composition according to this embodiment may be for producing a green sheet (i.e., an unfired ceramic sheet) that is applied to the manufacture of an LTCC substrate for STF. The slurry composition may include glass frit 10, a first filler 20 composed of a plurality of particulate first particles, a second filler 30 composed of a plurality of particulate second particles, a binder 40, and a solvent 50. The first filler 20 is a material for increasing the strength of the ceramic structure (or LTCC ceramic) obtained by firing the green sheet. The second filler 30 is a filler that plays a role in reducing the thermal expansion coefficient of the ceramic structure.

[0030] The glass frit 10 can have a material composition that allows it to react with part or all of the first filler 20 and part of the second filler 30 during the sintering process of the green sheet to form (precipitate) a predetermined crystal phase. In this process, part or all of the glass frit 10 may be consumed, and together with the generated crystal phase, the remaining glass frit component constitutes the matrix of the sintered LTCC ceramic structure. In one embodiment, the glass frit 10 may contain part or all of SiO2, Al2O3, MgO, CaO, SrO, BaO, B2O3, ZnO, Na2O, and K2O. These glass frits 10 can form a cordierite series crystal phase, anorthite series crystal phase, or garnite series crystal phase through the sintering process.

[0031] The aforementioned cordierite (Mg2Al2Si5O 18To form the crystalline phases of the cordierite, anorthite, and garnite series, the glass frit 10 may contain SiO2, Al2O3, and MgO components. To form the crystalline phase of the anorthite series, the glass frit 10 may contain CaO, Al2O3, and SiO2 components. To form the crystalline phase of the garnite series, the glass frit 10 may contain ZnO and Al2O3. To form the respective crystalline phases of the cordierite, anorthite, and garnite series, the glass frit may be consumed in the reactions during the sintering process, and the remainder may remain as glass components constituting the matrix of the fired LTCC ceramic. For example, SrO, BaO, B2O3, Na2O, and K2O constituting the glass frit 10 may remain as glass components within the fired LTCC ceramic structure. Such crystalline phases and glass components can improve the firing properties (i.e., low-temperature firing properties) and strengthen the green sheets produced therefrom.

[0032] As described above, the first filler 20 can react with the glass frit 10 in part or in whole during the firing process, thereby increasing the strength of the LTCC ceramic. In connection with this, the first filler 20 can have higher strength (physical strength) than the second filler 30. The first filler 20 may consist of a plurality of first particles. The first particles may have a diameter of, for example, about 0.2 μm to 5 μm. The first particles may include, for example, at least one of alumina (Al2O3), mullite (3Al2O3·2SiO2), and diopside (Ca(Mg,Fe)Si2O6). However, the specific material of the first filler 20 disclosed herein is illustrative, and other materials may be applied.

[0033] The second filler 30 can partially react with the glass frit 10 and / or the first filler 20 during the firing process, remain in the LTCC ceramic, and play a role in reducing the coefficient of thermal expansion (CTE) of the LTCC ceramic. In connection with this, the second filler 30 may have a lower coefficient of thermal expansion (CTE) than the first filler 20. The second filler 30 may include, for example, at least one of cordierite, fused silica, willemite (ZnSiO4), eucryptite (LiAlSiO4), zirconia (ZrO2), and celsian (BaAl2Si2O8). In other embodiments, the second filler 30 may further include zirconium tungstate (ZrW2O8) or wollastonite (CaSiO3). The second filler 30 can have a larger diameter on average than the first filler 20, for example, a diameter of about 0.5 μm to 10 μm. By having a larger diameter than the first filler 20, the second filler 30 can remain in sufficient quantity even as it is consumed during firing in the LTCC ceramic, effectively accommodating thermal deformation due to temperature changes in the matrix and reducing the thermal expansion coefficient of the LTCC ceramic.

[0034] Referring again to Figure 1, in the slurry composition, the ratio of the combined weight of the first filler 20 and the second filler 30 to the glass frit 10, that is, the ratio of the combined weight of each filler to the weight of the glass frit 10, is in the range of 30 wt% to 70 wt%, preferably in the range of 40 wt% to 60 wt%. In one embodiment, in the slurry composition, the weight ratio of the second filler 30 to the weight of the first filler 20 may be in the range of 20 wt% to 80 wt%, preferably in the range of 30 wt% to 65 wt%. The content of the second filler 30 can be adjusted so that only a portion of it reacts with the glass frit 10 and the first filler 20 during the calcination process, and a considerable portion remains. In the case of the first filler 20, it can react with the glass frit 10 during the calcination process to generate a crystalline phase, so the amount of first filler 20 added during slurry production can be intentionally increased, taking into account the amount consumed in generating the crystalline phase. A portion of the first filler 20 is consumed in the formation of the crystalline phase, and the remaining portion of the first filler 20 can play a role in increasing the strength of the LTCC substrate.

[0035] The binder 40 may include, for example, at least one of acrylic, epoxy, PVB (polyvinyl butyral), and EC (ethyl cellulose). The solvent 50 may include, for example, at least one of methanol, ethanol, isopropanol, methyl ethyl ketone, toluene, acetone, and diethyl ether. In the overall slurry composition, the content of the binder 40 may be, for example, about 6 wt% to 15 wt%, and the content of the solvent 50 may be, for example, about 20 wt% to 40 wt%. The slurry composition may also further contain dispersants and other additives.

[0036] Using the slurry composition according to the embodiments described above, a green sheet, i.e., an unsintered sheet, can be formed from the slurry composition. In one embodiment, the slurry composition can be cast by a method such as tape casting to form the green sheet. A wiring pattern may be formed on the surface of the green sheet, via holes may be formed in the thickness direction of the green sheet, and via conductors electrically connected to the wiring pattern can be formed by filling the via holes with a conductive material. The wiring pattern and via conductors may be low-resistance metals such as copper, silver, or alloys containing these, as non-limiting examples, and any metal known for forming LTCC substrates may be used.

[0037] Next, a laminated structure can be formed by stacking multiple green sheets, and the laminated structure can be fired to form an LTCC ceramic or LTCC substrate. The laminated structure may include wiring patterns formed on its surface and interior. As described above, the wiring patterns have a low melting point as a low-resistance metal, metal alloy, or compound, so that the firing can be a low-temperature firing carried out at a temperature of about 1,000°C or less. For example, the firing temperature may be in the range of about 600°C to 1,000°C. The LTCC substrate thus manufactured can be applied to the manufacture of an STF (space transformer) element through additional subsequent processes.

[0038] In the step of forming an LTCC substrate by firing the laminated structure, a portion of the glass frit 10, the first filler 20, and the second filler 30 react to form a predetermined crystalline material, thereby constituting the matrix. The remaining first filler 20 and the newly formed crystalline material enhance the strength of the LTCC substrate, while the remaining second filler 30 reduces the thermal expansion coefficient of the LTCC substrate. In one embodiment, the crystalline material may be a cordierite crystalline phase, anorthite crystalline phase, and garnite crystalline phase. In some embodiments, the crystalline material may further include a eucryptite crystalline phase.

[0039] Figure 2 is a schematic diagram illustrating the firing process of a ceramic sheet according to one embodiment of the present invention. Figure 2 shows the structure of the LTCC ceramic obtained after firing an unfired ceramic sheet (green sheet) obtained from a slurry composition according to an embodiment of the present invention described with reference to Figure 1 through heat treatment.

[0040] Referring to Figure 2, a green sheet according to one embodiment of the present invention may have a structure in which a first filler F10 composed of a plurality of first particles and a second filler F20 composed of a plurality of second particles are dispersed in a matrix layer M10'. Here, the matrix layer M10 may contain glass frit as its main constituent material and may further contain some other substances such as a binder. The glass frit may correspond to the glass frit 10 described with reference to Figure 1. The first filler F10 and the second filler F20 may correspond to the first filler 20 and the second filler 30 described with reference to Figure 1, respectively.

[0041] When an unfired ceramic sheet (green sheet) is fired, a portion of the glass frit M10 reacts with a portion or all of the first filler F10, and a portion of the glass frit M10 reacts with a portion of the second filler F20, causing crystalline material F30 to precipitate in the matrix. In the glass frit M10, any portion that does not participate in the reaction during firing may remain as glass material. Similarly, any portion of the first filler F10 that does not participate in the reaction during firing may also remain. On the other hand, the second filler F20 may react with the glass frit and the first filler F10 during the firing process, a portion of it may remain, or it may not be consumed without reacting with the glass frit and the first filler F10. In this case, the second filler F20 can maintain almost or largely the same state as before firing.

[0042] Therefore, referring to the post-sintering drawing on the right in Figure 2, the post-sintering LTCC ceramic can have a structure in which a first filler F10 composed of multiple first particles and a second filler F20 composed of multiple second particles are dispersed within the matrix layer M10'. Here, the matrix layer M10' may be completely consumed by the reaction with the first filler F10 or the second filler F20, or it may remain due to a partial reaction. Also, the glass phase forming the glass frit M10 before sintering and the matrix layer M10' after sintering may be the same or different. The crystalline material F30 generated after sintering may have cordierite (Mg2Al4Si5O) as its main constituent material. 18 It may contain at least one of the following crystalline phases: anorthite, garnite, willemite (ZnSiO4), eucryptite (LiAlSiO4), celsian (BaAl2Si2O8), wollastonite (CaSiO3), and zinc aluminate (ZnAl2O4).

[0043] The total amount of the first filler F10 may be less than the total amount of the first filler F10 in the green sheet before firing. This may be because some of the first filler F10 is consumed in forming the crystalline substance. In connection with this, the number of individual particles constituting the first filler F10 may decrease, or the volume (diameter) of each particle may decrease. On the other hand, some of the second filler F20 may also be consumed, but conversely, it may remain almost the same as or largely the same as before firing.

[0044] In the LTCC ceramic after firing, the content of the first filler F10 relative to the total amount of crystalline material F30, glass material, first filler F10, and second filler F20 may be approximately 10 wt% to 40 wt%. On the other hand, in the LTCC ceramic after firing, the content of the second filler F20 relative to the total amount of crystalline material, glass material, first filler F10, and second filler F20 may be approximately 5 wt% to 30 wt%. The material composition of the first filler F10 and the second filler F20 is as described with reference to Figure 1, so a further explanation is omitted.

[0045] Through firing, a portion of the first filler 20 is consumed in the formation of the crystalline phase, and the remaining portion of the first filler 20 can play a role in increasing the strength of the LTCC ceramic. In addition, the second filler 30 dispersed in the matrix layer M10' ensures a low coefficient of thermal expansion as a low expansion coefficient material that can accommodate thermal deformation due to temperature changes in the LTCC ceramic after firing. As a result, the LTCC ceramic according to the embodiment of the present invention can obtain a high strength of approximately 200 MPa while having a low coefficient of thermal expansion, for example, a coefficient of thermal expansion of 4.0 ppm / °C. When such LTCC ceramic is applied to LTCC substrates and even to space transducers, its low coefficient of thermal expansion while having high strength enables highly reliable, high-speed, and highly efficient testing in the evaluation of semiconductor devices conducted in a wide range of temperature regions.

[0046] Figure 3a shows the results of X-ray diffraction analysis of an LTCC ceramic according to an embodiment of the present invention, and Figure 3b shows the results of X-ray diffraction analysis of an LTCC ceramic according to a comparative example. The X-ray analysis was performed on the cross-section of the LTCC ceramic using Cu Kα rays as the light source. The diffraction angle 2θ ranged from 5° to 90°, and the scan speed was 0.0065° / step. In Figures 3a and 3b, the value of the X axis represents 2θ (degrees).

[0047] Referring to Figure 3a, in the analysis of LTCC ceramics after firing, samples having a strength of 200 MPa or more while exhibiting a thermal expansion coefficient of 4.0 ppm / °C or less may have a ratio of peak I2 derived from the cordierite crystal phase to peak I1 derived from the alumina crystal phase, i.e., I2 / I1, of approximately 0.14 or more, or approximately 0.15 or more. Furthermore, I2 / I1 may be less than approximately 1, for example. Preferably, I2 / I1 may be approximately 0.6 or less, or approximately 0.5 or less. The alumina crystal phase originates from the first filler (F10 in Figure 2), and the cordierite crystal phase originates from the matrix M10 and the second filler F20. Moreover, a low thermal expansion coefficient could be obtained when the ratio of peak I3 derived from the anorthite crystal phase to peak I1 derived from the alumina crystal phase, i.e., I3 / I1, was approximately 1.9 or more, or 2.0 or more. On the other hand, the ratio of peak I4 derived from the zinc aluminate crystalline phase to peak I1 derived from the alumina crystalline phase, i.e., I4 / I1, can be about 1.5 or less, about 1.2 or less, or about 1 or less. When I4 / I1 is about 1.5 or less, about 1.2 or less, or about 1 or less, a low coefficient of thermal expansion can be obtained.

[0048] In contrast, referring to Figure 3b, when the ratio I2 / I1 is less than 0.1, the coefficient of thermal expansion is high, at 4.3 or higher. This means that a portion of the glass frit M10 and a portion or most of the second filler F20 reacted and were almost completely consumed, and in this case, it was confirmed that there was no effect of reducing the coefficient of thermal expansion along with the strength.

[0049] Table 1 shows the analytical values ​​of intensity, thermal expansion coefficient, and peak ratio for the examples and comparative examples of the present invention.

[0050] [Table 1]

[0051] Referring to Table 1, ensuring high strength and low thermal expansion coefficient of LTCC ceramic materials after firing can be achieved by analyzing the ratio I2 / I1 without complex analysis, and selectively checking I3 / I1 and I4 / I1. This allows for the detection of LTCC ceramics with high strength while having a low thermal expansion coefficient, and enables the design of manufacturing processes targeting products with the aforementioned XRD strength ratios. Table 2 below summarizes the X-ray diffraction analysis and physical property evaluation results of LTCC ceramics according to each embodiment of the present invention.

[0052] [Table 2]

[0053] Referring to Table 2 above, in the analysis of the LTCC ceramic after firing, the ratio of peak I2 derived from the cordierite crystal phase to peak I1 derived from the alumina crystal phase, i.e., I2 / I1, may be about 0.14 or more, or about 0.15 or more. Also, I2 / I1 may be less than about 1, for example. Preferably, I2 / I1 may be about 0.6 or less, or about 0.5 or less. The alumina crystal phase may originate from the first filler (F10 in Figure 2), and the cordierite crystal phase may originate from the matrix M10 and the second filler F20. The ratio of peak I3 derived from the anorthite crystal phase to peak I1 derived from the alumina crystal phase, i.e., I3 / I1, may be about 1.9 or more, or 2.0 or more. As a non-limiting example, I3 / I1 may be about 5 or less, or about 4 or less. When the ratio of I3 / I1 is approximately 1.9 or greater, or 2.0 or greater, it may be advantageous to obtain a low coefficient of thermal expansion. On the other hand, the ratio of peak I4 derived from the zinc aluminate crystalline phase to peak I1 derived from the alumina crystalline phase, i.e., I4 / I1, may be approximately 1.5 or less, approximately 1.2 or less, or approximately 1 or less. When the ratio of I4 / I1 is approximately 1.5 or less, approximately 1.2 or less, or approximately 1 or less, it may be advantageous to obtain a low coefficient of thermal expansion.

[0054] In Table 2 above, Al2O3(1) corresponds to one of the two main 2θ values ​​of Al2O3 (corresponding to 35.1 degrees), and Al2O3(2) corresponds to the other of the two main 2θ values ​​of Al2O3 (corresponding to 43.3 degrees). The peak intensities of the alumina crystalline phases used in I2 / I1, I3 / I1, and I4 / I1 may be the peak intensities of Al2O3(2). On the other hand, ZnAl2O4 may be garnite.

[0055] Furthermore, as shown in Table 2, the LTCC ceramic (LTCC ceramic substrate) according to the embodiment of the present invention has a low coefficient of thermal expansion of approximately 4.0 ppm / °C or less, while also having a high bending strength of approximately 180 MPa or more or approximately 200 MPa or more. Here, the bending strength was measured using a UTM (Universal Testing Machine) under three-point bending strength conditions.

[0056] Figure 4 is a scanning electron microscope (SEM) image showing the microstructure of the LTCC ceramic corresponding to Example 3 in Table 2.

[0057] Figure 5 is an SEM image showing the microstructure of the LTCC ceramic corresponding to Example 7 in Table 2.

[0058] Figure 6 is an SEM image showing the microstructure of the LTCC ceramic corresponding to Example 5 in Table 2.

[0059] Figure 7 is an SEM image showing the microstructure of the LTCC ceramic corresponding to Example 10 in Table 2.

[0060] Figure 8 is a graph showing the ratio of peak I2 derived from the cordierite crystal phase to peak I1 derived from the alumina crystal phase (i.e., I2 / I1), flexural strength, and coefficient of thermal expansion (CTE) of LTCC ceramics according to each embodiment of the present invention.

[0061] Referring to Figure 8, the samples in Examples 3 and 10 are shrinkable LTCC, while the samples in Examples 7 and 5 are non-shrinkable LTCC. The coefficient of thermal expansion (CTE) tended to decrease as I2 / I1 increased within a given range. All samples could have a low coefficient of thermal expansion of approximately 4.0 ppm / °C or less. Furthermore, all samples could have a high bending strength of approximately 180 MPa or more.

[0062] Figure 9 is a graph showing the results of X-ray diffraction analysis of LTCC ceramics according to an embodiment of the present invention. Figure 9 shows the results for Example 2 in Table 2.

[0063] Table 3 below, obtained from Figure 9, summarizes the 2θ and peak intensities of each crystal phase.

[0064] [Table 3]

[0065] Table 4 below summarizes the thermal expansion coefficient (CTE), Er, and strength of anorthite, alumina (Al2O3), cordierite, and garnite. Here, the unit of thermal expansion coefficient (CTE) is ppm / °C, and the unit of strength is MPa. On the other hand, Er represents the dielectric constant, and its unit is F / m.

[0066] [Table 4]

[0067] Figure 10 is a graph showing the results of X-ray diffraction analysis of an LTCC ceramic according to an embodiment of the present invention. Figure 10 shows the results for a sample corresponding to Example 5 in Table 2. In this case, the EL was 80 μm. Here, the EL represents a ceramic sheet mixed with glass and cordierite.

[0068] Figure 11 is a graph showing the results of X-ray diffraction analysis of an LTCC ceramic according to an embodiment of the present invention. Figure 11 shows the results for a sample corresponding to Example 5 in Table 2. At this time, the EL was 70 μm.

[0069] Figure 12 is a graph showing the results of X-ray diffraction analysis of an LTCC ceramic according to an embodiment of the present invention. Figure 12 shows the results for a sample corresponding to Example 7 in Table 2.

[0070] Figure 13 is a graph showing the results of X-ray diffraction analysis of an LTCC ceramic according to an embodiment of the present invention. Figure 13 shows the results for a sample corresponding to Example 3 in Table 2.

[0071] Figure 14 is a graph showing the results of X-ray diffraction analysis of an LTCC ceramic according to an embodiment of the present invention. Figure 14 shows the results for a sample corresponding to Example 10 in Table 2.

[0072] Figure 15 is a cross-sectional view illustrating an exemplary laminated substrate structure for manufacturing an LTCC substrate according to one embodiment of the present invention.

[0073] Referring to Figure 15, the laminated substrate structure for manufacturing the LTCC substrate according to this embodiment may include a plurality of green sheets (unfired ceramic sheets) 101. The thickness of each green sheet 101 may be, for example, about 20 μm to 200 μm. Multiple via holes VH may be formed in the plurality of green sheets 101, and conductive plugs 103 may be formed in the via holes VH. In addition, a conductive pattern layer 104 may be formed between the plurality of green sheets 101 to electrically connect each conductive plug 103. The arrangement of the via holes VH, and the arrangement and shape of the conductive plugs 103 and conductive pattern layer 104 are illustrative and can be varied in many ways.

[0074] After forming via holes VH on the unfired green sheet as described in Figure 2, conductive plugs 103 and conductive pattern layers 104 can be formed. Multiple such unfired green sheets can be stacked to manufacture a laminated substrate structure as shown in Figure 15. Therefore, the material composition of the multiple green sheets 101 in Figure 15 can correspond to the material composition of the green sheet before firing in Figure 2. An LTCC substrate can be manufactured by performing a firing process (low-temperature firing process) on the laminated substrate structure.

[0075] According to other embodiments of the present invention, some of the multiple ceramic sheets 101 may have a different material composition from the green sheet before firing shown in Figure 2.

[0076] Figure 16 is a cross-sectional view illustrating an exemplary laminated substrate structure for manufacturing an LTCC substrate according to another embodiment of the present invention.

[0077] Referring to Figure 16, the laminated substrate structure for manufacturing the LTCC substrate according to this embodiment may include a structure in which at least one green sheet 101 and at least one restraining sheet 102 are laminated. For example, at least one green sheet 101 and at least one restraining sheet 102 may be repeatedly laminated alternately. Via holes VH may be formed in the ceramic sheet 101 and the restraining sheet 102, and conductive plugs 103 may be formed in the via holes VH. In addition, a conductive pattern layer 104 may be formed between the green sheet 101 and the restraining sheet 102 for electrically connecting each conductive plug 103. The arrangement of the via holes VH, and the arrangement and shape of the conductive plugs 103 and conductive pattern layer 104 are exemplary and can be varied in many ways. Furthermore, the lamination order and arrangement method of the green sheet 101 and the restraining sheet 102 can be varied in many ways.

[0078] The material composition of the green sheet 101 may correspond to the material composition of the green sheet before firing, as described with reference to Figure 2. The thickness of the green sheet 101 may be, for example, about 20 μm to 200 μm. On the other hand, the restraining sheet 102 can play a role in suppressing / preventing or minimizing the firing shrinkage of the entire laminated substrate structure during the firing process. The restraining sheet 102 may have a higher firing temperature than the green sheet 101. Also, the restraining sheet 102 may have a lower shrinkage rate than the green sheet 101 during the firing process. The restraining sheet 102 may be an unfired ceramic sheet having a different material composition from the green sheet 101. The restraining sheet 102 may have a very low glass content so as not to be fired (sintered) at the firing (sintering) temperature of the ceramic sheet 101. The restraining sheet 102 may include, for example, alumina (Al2O3) as a main constituent material. Therefore, the restraining sheet 102 may be an alumina-based ceramic sheet. Furthermore, the restraint sheet 102 may further include a ceramic filler and an organic binder. The restraint sheet 102 may have a thinner thickness than the ceramic sheet 101, but may, if applicable, have a thickness similar to that of the ceramic sheet 101.

[0079] An LTCC substrate can be manufactured by performing a firing process (low-temperature firing process) on the laminated substrate structure shown in Figure 16. During this firing process, the glass component of the green sheet 101 can penetrate (diffuse) into the interior of the restraining sheet 102, and interlayer bonding and sintering effects can occur due to this penetration (diffusion) of the glass component. The restraining sheet 102 can play a role in achieving a non-shrinkage process for the laminated substrate structure during the firing process.

[0080] Figure 17 is a cross-sectional view illustrating an STF (space transformer) manufactured according to one embodiment of the present invention.

[0081] Referring to Figure 17, the STF manufactured according to the embodiment of the present invention may include an LTCC substrate LS10 and may include a wiring layer member WL10 formed on the upper surface of the LTCC substrate LS10. The LTCC substrate LS10 may be manufactured according to the embodiment described with reference to Figures 1 to 16, etc. The wiring layer member WL10 can be formed into a multilayer wiring layer by alternately laminating a metal wiring pattern layer and an organic insulating layer (interlayer insulating film) on the upper surface of the LTCC substrate LS10. Conductive via structures may be formed in the organic insulating layer. The organic insulating layer may include, for example, polyimide (PI), but is not limited to this material.

[0082] Multiple first electrode pads PD10 can be formed on the wiring layer member WL10. Multiple microprobes are placed on the multiple first electrode pads PD10. On the lower surface of the LTCC substrate LS10, wiring is formed to achieve electrical connection with the printed circuit board for power and signal transmission to the tester, or connections are made to pogo pins.

[0083] Figure 18 is a cross-sectional view illustrating a probe card containing an STF manufactured according to one embodiment of the present invention.

[0084] Referring to Figure 18, a probe card according to an embodiment of the present invention may be configured to include a printed circuit board 1 to which an electrical signal is applied from the outside, an STF (space transformer) 3 having a plurality of microprobes 2 that contact connection pads of an object to be tested (not shown), such as a semiconductor chip, and an interface member 4 that alternately electrically connects the printed circuit board 1 and the STF 3. Here, the STF 3 may be an electronic circuit board that electrically connects the printed circuit board 1 and a plurality of microprobes 2 of several tens of micrometers in size while performing pitch conversion for testing ultra-high-integration semiconductor elements. Although not shown, the printed circuit board 1 may be connected to a predetermined tester device. The probe card can play a role in connecting numerous measurement points (wafer pads) present on a wafer that is to be tested (not shown) to the tester device.

[0085] A method for manufacturing a probe card according to an embodiment of the present invention may include the steps of: manufacturing an LTCC substrate using the method described above; manufacturing an STF containing the LTCC substrate; and manufacturing a probe card to which the STF has been applied.

[0086] As described above, each embodiment of the present invention makes it possible to realize an LTCC substrate having high strength and low expansion (i.e., low thermal expansion) characteristics. Furthermore, by using an STF to which the LTCC substrate according to each embodiment of the present invention is applied, it is possible to manufacture a probe card with high strength and high reliability.

[0087] This specification discloses preferred embodiments of the present invention, and specific terms are used, but these are merely general terms used to facilitate the explanation of the technical content of the invention and to promote understanding of the invention, and are not intended to limit the scope of the invention. It will be obvious to a person ordinary skill in the art to which the present invention pertains that other modifications based on the technical idea of ​​the present invention are possible, in addition to the embodiments disclosed herein. For example, a person ordinary skill in the art will see that the slurry composition for manufacturing an LTCC substrate, the method for manufacturing an LTCC substrate, the LTCC substrate, the probe card, and the method for manufacturing the probe card according to each embodiment described with reference to Figures 1 to 18 are highly modifiable. Therefore, the scope of the invention should not be defined by the embodiments described herein, but by the technical idea described in the claims. [Industrial applicability]

[0088] Each embodiment of the present invention may be applied to ceramic structures and elements / devices containing the same. Each embodiment of the present invention may be applied to co-fired ceramic substrates and spatial transducers and probe cards containing the same.

Claims

1. Cordierite (Mg ２ Al ４ Si ５ O １８ ) and alumina (Alumina; Al ２ O ３ ) including, In the X-ray diffraction analysis by Cu Kα irradiation, peak I derived from the alumina １ to peak I derived from the cordierite ２ ratio I ２ / I １ is a ceramic substrate of 0.15 or more.

2. The ceramic substrate according to claim 1, further comprising anorthite and garnite.

3. The ceramic substrate comprises a matrix containing a glass component, a plurality of particulate first fillers dispersed within the matrix, and a plurality of particulate second fillers. The ceramic substrate according to claim 1, wherein the first filler has a higher strength than the second filler, and the second filler has a lower coefficient of thermal expansion than the first filler.

4. The ceramic substrate according to claim 3, wherein the first filler comprises at least one of alumina, mullite, and diopside.

5. The ceramic substrate according to claim 3, wherein the second filler comprises at least one of cordierite, fused silica, willemite, eucryptite, zirconia, and celsian.

6. An LTCC (low temperature co-fired ceramic) substrate for STF (space transformer), It contains fired ceramic sheets, The fired ceramic sheet is A matrix layer containing crystalline and glassy materials; A particulate first filler dispersed within the matrix layer; and The matrix layer comprises a particulate second filler dispersed within the matrix layer; An LTCC substrate for STF, wherein the first filler has higher strength than the second filler, and the second filler has a lower coefficient of thermal expansion than the first filler.

7. The aforementioned ceramic sheet is made of cordierite (Mg ２ Al ４ Si ５ O １８ ) and alumina (Alumina; Al ２ O ３ ) including, In X-ray diffraction analysis induced by Cu Kα irradiation, the peak I induced from the alumina was １ Peak I derived from the cordierite for the above ２ Ratio I ２ / I １ The LTCC substrate for STF according to claim 6, wherein the ratio is 0.15 or greater.

8. The LTCC substrate for STF according to claim 6, wherein the first filler comprises at least one of alumina, mullite, and diopside.

9. The LTCC substrate for STF according to claim 6, wherein the second filler comprises at least one of cordierite, fused silica, willemite, eucryptite, zirconia, and celsian.

10. The LTCC substrate for STF according to claim 6, wherein the crystalline material further comprises anorthite and garnite.

11. A probe card comprising an STF (space transformer) to which the LTCC substrate described in any one of claims 6 to 10 is applied.

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