Ceramic substrate and method for manufacturing the same, electrostatic chuck, substrate fixing device, and semiconductor device package

Abstract

A ceramic substrate includes a substrate body, an electric conductor layer built in the substrate body, and a via built in the substrate body and electrically connected to the electric conductor layer. The substrate body is made of a ceramic containing alumina. The via is made of a sintered body of an electric conductor paste. The electric conductor paste contains molybdenum as a main component, and further contains nickel oxide, alumina, and silicon dioxide.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to Japanese Patent Application No. 2020-076847, filed on April 23, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to ceramic substrates, methods for manufacturing ceramic substrates, electrostatic chucks, substrate fixing devices, and semiconductor device packaging. Background Technology

[0004] In the background art, film deposition equipment or plasma etching equipment for manufacturing semiconductor devices has a stage for precisely holding wafers in a vacuum processing chamber. For example, a substrate holding device that uses an electrostatic chuck mounted on a base plate to attract and hold the wafer has been proposed as such a stage.

[0005] An electrostatic chuck includes a substrate body, electrostatic electrodes built into the substrate body, and a ceramic substrate having vias electrically connected to the electrostatic electrodes. The electrostatic electrodes or vias are fabricated as follows: (for example) a conductive paste containing high-melting-point metal powder such as tungsten (W), molybdenum (Mo), or molybdenum-manganese (Mo-Mn) alloy, a resin binder, etc., is formed on a ceramic green sheet by screen printing or similar methods, and then the sheet is fired (see, for example, JP-A-2011-228727).

[0006] However, alumina ceramics typically contain sintering aids (e.g., silica, magnesium oxide, calcium oxide, or yttrium oxide). Therefore, the insulation resistance of ceramics containing sintering aids tends to decrease with increasing ambient temperature. To address this issue, alumina ceramics without sintering aids, exhibiting a lower temperature dependence of insulation resistance, are desirable. However, since no sintering aids are available to transform into a liquid phase during sintering, in ceramic substrates such as electrostatic chucks, the bonding strength between the ceramic forming the substrate body and the vias cannot be guaranteed. Summary of the Invention

[0007] This disclosure provides a ceramic substrate in which the bonding strength between the ceramic forming the substrate body and the vias is improved.

[0008] One embodiment provides a ceramic substrate comprising: a substrate body; an electrical conductor layer embedded in the substrate body; and vias embedded in the substrate body and electrically connected to the electrical conductor layer. The substrate body is made of a ceramic comprising alumina. The vias are formed by a sintered body of an electrical conductor paste. The electrical conductor paste comprises molybdenum as a main component and also comprises nickel oxide, alumina, and silicon dioxide. Attached Figure Description

[0009] Figure 1 A simplified cross-sectional view of the substrate fixing device according to the first embodiment is shown.

[0010] Figure 2 A simplified plan view of the substrate fixing device according to the first embodiment is shown.

[0011] Figures 3A to 3D A side view (part 1) showing the manufacturing process of the electrostatic chuck according to the first embodiment;

[0012] Figures 4A to 4C A side view (part 2) showing the manufacturing process of the electrostatic chuck according to the first embodiment;

[0013] Figures 5A to 5C A cross-sectional view for explaining the embodiments;

[0014] Figure 6A and 6B A diagram showing SEM images of Comparative Example 1 and Example 1;

[0015] Figure 7 A graph showing the EPMA analysis results for the cross section of Comparative Example 1;

[0016] Figure 8 A graph showing the EPMA analysis results of the cross section of Example 1;

[0017] Figure 9A and 9B A graph showing the XRD analysis results of the exposed ceramic portions according to Example 2 and Comparative Example 2;

[0018] Figure 10 A cross-sectional view of a semiconductor device package according to a second embodiment is shown; and

[0019] Figure 11 A plan view of a semiconductor device package according to a second embodiment is shown. Detailed Implementation

[0020] The embodiments of this disclosure will now be described with reference to the accompanying drawings. In the drawings, the same reference numerals will be used to indicate the corresponding components, and repeated descriptions may be omitted.

[0021] (First Implementation Plan)

[0022] [Structure of the substrate fixing device]

[0023] Figure 1 A cross-sectional view of the substrate fixing device according to the first embodiment is shown in a simplified manner. Figure 1As shown, the substrate fixing device 1 includes a base plate 10 and an electrostatic chuck 20 as its main components. The substrate fixing device 1 is a device that uses the electrostatic chuck 20 to adsorb and hold a substrate W (e.g., a semiconductor wafer) as the adsorption target object.

[0024] The base plate 10 is a component for mounting the electrostatic chuck 20 thereon. The thickness of the base plate 10 is, for example, about 20 mm to 40 mm. The base plate 10 is, for example, made of a metallic material such as aluminum or hard alloy, or a composite material of metallic and ceramic materials, and the base plate 10 can be used as an electrode for controlling plasma. For example, from the viewpoints of availability, ease of processing, and excellent thermal conductivity, aluminum or aluminum alloys with an alumina film treatment (forming an insulating layer) can be suitable for the base plate 10.

[0025] For example, the energy used to cause plasma-generated ions to collide with the substrate W adsorbed on the electrostatic chuck 20 can be controlled by supplying a predetermined high-frequency power to the base plate 10. Therefore, the substrate W can be effectively etched.

[0026] Inside the base plate 10, a gas supply path can be provided for introducing an inert gas to cool the substrate W adsorbed on the electrostatic chuck 20. When an inert gas such as He or Ar is introduced into the gas supply path from outside the substrate holding device 1 and supplied to the back side of the substrate W adsorbed on the electrostatic chuck 20, the substrate W can be cooled.

[0027] A refrigerant flow path can be provided inside the base plate 10. For example, the refrigerant flow path is a hole formed in an annular shape inside the base plate 10. For example, a refrigerant such as cooling water or Galden is introduced into the refrigerant flow path from outside the substrate fixing device 1. When the refrigerant is circulated in the refrigerant flow path to cool the base plate 10, the substrate W adsorbed on the electrostatic chuck 20 can be cooled.

[0028] The electrostatic chuck 20 is the part that adsorbs and holds the substrate W, which is the target object for adsorption. The planar shape of the electrostatic chuck 20 is formed according to the shape of the substrate W. For example, the planar shape of the electrostatic chuck 20 is circular. The diameter of the wafer, which is the target object for adsorption by the electrostatic chuck 20, is, for example, 8 inches, 12 inches, or 18 inches.

[0029] A plan view refers to a view of the target object as seen from the normal direction of the top surface 10a of the base plate 10, and a planar shape refers to the shape of the target object as seen from the normal direction of the top surface 10a of the base plate 10.

[0030] The electrostatic chuck 20 is mounted on the top surface 10a of the base plate 10 via an adhesive layer. The adhesive layer is, for example, a silicone-based adhesive. The thickness of the adhesive layer is, for example, approximately 0.1 mm to 2.0 mm. The adhesive layer has the effect of bonding the base plate 10 and the electrostatic chuck 20 together and reducing stress caused by the difference in the coefficients of thermal expansion between the ceramic electrostatic chuck 20 and the aluminum base plate 10. The electrostatic chuck 20 can be secured to the base plate 10 with screws.

[0031] The electrostatic chuck 20 is a ceramic substrate having a substrate body 21, electrostatic electrodes 22 (an example of an electrical conductor layer), vias 23a and 23b, and a heating element 24 as its main components. The top surface of the substrate body 21 is a mounting surface 21a for mounting and adsorbing target objects. The electrostatic chuck 20 is, for example, a Johnsen-Rahbek type electrostatic chuck. However, the electrostatic chuck 20 can also be a Coulomb force type electrostatic chuck.

[0032] The substrate body 21 is a dielectric. Specifically, the substrate body 21 is made of ceramic containing alumina (Al2O3). The thickness of the substrate body 21 is, for example, about 5 mm to 10 mm. Furthermore, at an AC voltage frequency of 1 kHz, the relative permittivity of the substrate body 21 is, for example, about 9 to 10.

[0033] The purity of alumina in the substrate body 21 is preferably 99.5% or higher. A purity of 99.5% or higher means that the substrate body 21 is formed without the addition of any sintering aids. Furthermore, a purity of 99.5% or higher means that unintended impurities may be present during the manufacturing process, etc. The relative density of the substrate body 21 relative to alumina is preferably 97% or higher. The average particle size of the alumina in the substrate body 21 is preferably 1.0 μm or more and 3.0 μm or less.

[0034] The electrostatic electrode 22 is, for example, a thin-film electrode formed from an electrical conductor pattern. The electrostatic electrode 22 is embedded in the substrate body 21. In this embodiment, the electrostatic electrode 22 is a bipolar electrode and has a first electrostatic electrode 22a and a second electrostatic electrode 22b. Alternatively, a unipolar electrode consisting of a single electrostatic electrode can be used as the electrostatic electrode 22.

[0035] The first electrostatic electrode 22a is electrically connected to the via 23a and is connected to the positive electrode side of the power supply 40a through the via 23a. The power supply 40a is located outside the substrate fixing device 1. Furthermore, the second electrostatic electrode 22b is electrically connected to the via 23b and is connected to the negative electrode side of the power supply 40b through the via 23b. The power supply 40b is located outside the substrate fixing device 1. The negative electrode side of the power supply 40a and the positive electrode side of the power supply 40b are connected outside the substrate fixing device 1, and their contact point has a ground potential.

[0036] Each via 23a and 23b is made of a sintered body containing molybdenum as the main component, and also containing nickel oxide, aluminum oxide, and silicon dioxide. Because the vias 23a and 23b contain molybdenum, nickel oxide, aluminum oxide, and silicon dioxide, the bonding strength between the ceramic forming the substrate body 21 and the vias 23a and 23b can be improved even when the substrate body 21 is made of ceramic containing aluminum oxide (Al2O3) formed without the addition of any sintering aids.

[0037] Furthermore, it is preferable to use a conductive paste containing tungsten (W) as the main component and also containing nickel oxide (NiO), aluminum oxide, and silicon dioxide (SiO2) as the material for the electrostatic electrode 22. In this case, even if the vias 23a and 23b contain molybdenum, nickel oxide, aluminum oxide, and silicon dioxide, the adhesion between the electrostatic electrode 22 and the vias 23a and 23b can be improved.

[0038] Vias 23a and 23b are preferably formed from a sintered body of a conductive paste in which the amount of nickel oxide added relative to molybdenum is from 0.2% to 1.0% by weight. Furthermore, it is preferred that vias 23a and 23b are sintered bodies of a conductive paste in which the amounts of alumina and silicon dioxide added relative to molybdenum are from 2.0% to 20.0% by weight and from 0.2% to 3.0% by weight, respectively. Furthermore, preferably, the average particle size of molybdenum contained in the vias 23a and 23b is 0.5 μm to 3.0 μm, the average particle size of nickel oxide contained in the vias 23a and 23b is 5.0 μm to 15.0 μm, the average particle size of aluminum oxide contained in the vias 23a and 23b is 0.1 μm to 4.0 μm, and the average particle size of silicon dioxide contained in the vias 23a and 23b is 0.1 μm to 12.0 μm. Each average particle size can be determined, for example, using a laser diffraction / scattering device.

[0039] Incidentally, a pad can be provided at one end of the via 23a, with the end having the pad located on the opposite side of the via 23a from the end opposite to the first electrostatic electrode 22a. Another pad can be provided at one end of the via 23b, with the end having the pad located on the opposite side of the via 23b from the end opposite to the second electrostatic electrode 22b. The pad at one end of the via 23a can be connected to the power supply 40a, and the pad at one end of the via 23b can be connected to the power supply 40b.

[0040] Power supply 40a applies a positive (+) voltage to the first electrostatic electrode 22a through via 23a, and power supply 40b applies a negative (-) voltage to the second electrostatic electrode 22b through via 23b. As a result, the first electrostatic electrode 22a carries a positive (+) charge, and the second electrostatic electrode 22b carries a negative (-) charge. Consequently, a negative (-) charge is induced in the portion Wa of the substrate W opposite to the first electrostatic electrode 22a, and a positive (+) charge is induced in the portion Wb of the substrate W opposite to the second electrostatic electrode 22b.

[0041] When the substrate W, the electrostatic electrode 22, and the ceramic portion 25 (substrate body 21) of the electrostatic chuck 20 disposed between the substrate W and the electrostatic electrode 22 are considered as capacitors, the ceramic portion 25 corresponds to the dielectric layer. The substrate W is electrostatically attracted to the electrostatic chuck 20 by a Coulomb force generated between the electrostatic electrode 22 and the substrate W and passing through the ceramic portion 25. The higher the voltage applied to the electrostatic electrode 22, the stronger the attraction force.

[0042] The heating element 24 is embedded in the substrate body 21. The heating element 24 is a heater to which current is supplied to heat the substrate body 21, allowing the mounting surface 21a of the substrate body 21 to reach a predetermined temperature. The heating element 24 is positioned below the first electrostatic electrode 22a and the second electrostatic electrode 22b (on the base plate 10 side). The heating element 24 is an electrical conductor formed as a film. The heating element 24 functions as a heater electrode capable of independently controlling the heating of certain areas (heater areas) of the substrate body 21.

[0043] A heater electrode can be provided as the heating element 24. For example, a conductive paste containing tungsten as the main component and with added nickel oxide, aluminum oxide and silicon dioxide can be used as the material of the heating element 24.

[0044] When current is supplied to the heating element 24 by a power source located outside the substrate fixing device 1, the heating element 24 generates heat and heats the electrostatic chuck 20. The substrate W is controlled at a predetermined temperature by the temperature of the electrostatic chuck 20. The heating temperature of the electrostatic chuck 20 is set in the range of 50°C to 200°C. For example, the heating temperature of the electrostatic chuck 20 is set at, for example, 150°C.

[0045] Figure 2 A plan view of the substrate fixing device according to the first embodiment is shown in a simplified manner. Figure 2 As shown, in the substrate fixing device 1, an electrostatic chuck 20 is disposed on a disc-shaped base plate 10, and the peripheral portion of the base plate 10 is exposed around the electrostatic chuck 20. Attachment holes 11 for attaching the substrate fixing device 1 to the chamber of a semiconductor manufacturing equipment are formed on the peripheral portion of the base plate 10, and these attachment holes 11 are arranged along the peripheral portion.

[0046] In addition, the electrostatic chuck 20 and the base plate 10 each have multiple ( ) in their central portions. Figure 2 There are three lifting pin opening portions 12. The lifting pins that move the substrate W in the up / down direction are respectively inserted into the lifting pin opening portions 12. When the substrate W is moved upward from the mounting surface 21a by the lifting pins, the substrate W can be automatically transported by the transport device.

[0047] [Manufacturing method of electrostatic chuck]

[0048] Next, the manufacturing method of the electrostatic chuck 20 will be described. Figures 3A to 4C A side view illustrating the manufacturing process of an electrostatic chuck according to a first embodiment.

[0049] First, such as Figure 3A As shown, a green sheet 51 made of ceramic and organic materials is prepared. For example, the green sheet 51 is formed into a rectangular plate shape. The ceramic material of the green sheet 51 contains alumina but does not contain any sintering aids. The organic components in the green sheet 51 are removed, and the ceramic material is sintered and densified. Thus, the green sheet 51 is used as the substrate body 21 for mounting... Figure 1 The portion of the substrate W shown.

[0050] Next, as Figure 3B As shown, a green sheet 52 is prepared, made of the same material as the green sheet 51 and having the same shape as the green sheet 51, and a through-hole conductor 54 is formed in the green sheet 52. The green sheet 52 is fired to serve as the portion of the substrate 21 located between the electrostatic electrode 22 and the heating element 24, in order to facilitate the formation of... Figure 1 The electrostatic electrode 22 and the vias 23a and 23b are shown.

[0051] Furthermore, the via conductor 54 is fired in the steps described below to form Figure 1 A portion of the vias 23a and 23b are shown. The via conductor 54 is formed as follows. That is, a through-hole is formed at a predetermined location on the green sheet 52. For example, conductive paste is filled into the through-hole by a printing method (screen printing).

[0052] The conductive paste used to form the via conductor 54 is made from a mixture of molybdenum (main component), nickel oxide, aluminum oxide, silicon dioxide, and organic materials. The amount of nickel oxide added relative to molybdenum is preferably 0.2% by weight or more and 1.0% by weight or less. To improve the sinterability of molybdenum, it is preferable to add 0.2% by weight or more of nickel oxide. On the other hand, if 5% by weight or more of nickel oxide is added, the molybdenum crystals become too large, thus failing to achieve sufficient adhesion between the via and the substrate 21. To simultaneously fire the conductive paste and the green sheet, the average particle size of molybdenum is preferably 0.5 μm or more and 3.0 μm or less. Similarly, the average particle size of nickel oxide is preferably 5.0 μm or more and 15.0 μm or less.

[0053] The amount of alumina added is preferably 2.0% to 20.0% by weight, relative to molybdenum. Furthermore, from the viewpoint of shrinkage rate and resistivity of the vias caused by firing, the amount of alumina added is more preferably 7.0% to 15.0% by weight. To simultaneously fire the conductive paste and the green sheet, the average particle size of the alumina is preferably 0.1 μm to 4.0 μm.

[0054] The amount of silica added is preferably 0.2% by weight or more and 3.0% by weight or less, relative to molybdenum. Silica transforms into a liquid phase during the firing process. Therefore, to improve the sinterability of molybdenum and the adhesion between the vias and the substrate body 21, it is preferable to add 0.2% by weight or more of silica. On the other hand, if more than 3.0% by weight of silica is added, the sinterability and adhesion decrease. Furthermore, the resistivity increases. In order to simultaneously fire the conductive paste and the green sheet, the average particle size of silica is preferably 0.1 μm or more and 12.0 μm or less.

[0055] Next, as Figure 3C As shown, a conductive paste is printed onto the top surface of the green sheet 52 (e.g., by a printing method, such as screen printing) to form an electrical conductor pattern 55. This electrical conductor pattern 55 is then fired in the steps described below to be used as... Figure 1 The electrostatic electrode 22 shown.

[0056] The conductive paste used to form the electrical conductor pattern 55 is, for example, made from a mixture of tungsten (the main component), nickel oxide, aluminum oxide, silicon dioxide, and organic materials. The amount of nickel oxide added relative to tungsten is preferably 0.2% by weight or more and 1.0% by weight or less. To improve the sinterability of tungsten, it is preferable to add 0.2% by weight or more of nickel oxide. On the other hand, if 5% by weight or more of nickel oxide is added, the tungsten crystals become too large, thus failing to achieve sufficient adhesion between the electrostatic electrode 22 and the substrate body 21. To simultaneously fire the conductive paste and the green sheet, the average particle size of the tungsten is preferably 0.5 μm or more and 3.0 μm or less. Similarly, the average particle size of the nickel oxide is preferably 5.0 μm or more and 15.0 μm or less.

[0057] The amount of alumina added relative to tungsten is preferably 0.2% by weight or more and 3.0% by weight or less. To improve the adhesion between the electrostatic electrode 22 and the substrate body 21 made of ceramic containing alumina, it is preferable to add 0.2% by weight or more of alumina. On the other hand, if more than 3.0% by weight of alumina is added, the sinterability decreases. Furthermore, the resistivity increases. To simultaneously fire the conductive paste and the green sheet, the average particle size of the alumina is preferably 1.0 μm or more and 4.0 μm or less.

[0058] The amount of silicon dioxide added relative to tungsten is preferably 0.2% by weight or more and 3.0% by weight or less. Silicon dioxide transforms into a liquid phase during the firing process. Therefore, to improve the sinterability of tungsten and the adhesion between the electrostatic electrode and the substrate body 21, it is preferable to add 0.2% by weight or more of silicon dioxide. On the other hand, if more than 3.0% by weight of silicon dioxide is added, the sinterability and adhesion decrease. Furthermore, the resistivity increases. In order to simultaneously fire the conductive paste and the green sheet, the average particle size of silicon dioxide is preferably 1.0 μm or more and 12.0 μm or less.

[0059] Next, as Figure 3D As shown, a green sheet 53 is prepared, made of the same material as the green sheet 51 and having the same shape as the green sheet 51, and a through-hole conductor 56 is formed on the green sheet 53. The green sheet 53 is fired to serve as the part of the substrate body 21 bonded to the base plate 10, thereby forming Figure 1 The heating element 24 is shown.

[0060] Furthermore, the via conductor 56 is fired in the steps described below to form Figure 1 The remaining portions of the vias 23a and 23b are shown. For example, the via conductor 56 can be formed by the same method as the via conductor 54. The via conductor 54 and via conductor 56 are formed at locations where the via conductor 54 and via conductor 56 can be electrically connected to each other when the green sheets 52 and 53 are stacked on top of each other.

[0061] Next, conductive paste is printed onto the top surface of the green sheet 53, for example, by a printing method (screen printing), thereby forming an electrical conductor pattern 57. A conductive paste made of the same material as the conductive paste used to form the electrical conductor pattern 55 can be used as the conductive paste for forming the conductor pattern 57. The electrical conductor pattern 57 is fired in the steps described below to serve as a heating element 24. The electrical conductor pattern 57 can also be formed on the bottom surface of the green sheet 52.

[0062] Next, as Figure 4A As shown, green sheets 51 to 53 are stacked to form structure 71a. The green sheets 51 to 53 are pressed while being heated to bond them together. Next, as... Figure 4B As shown, the outer periphery of structure 71a is removed to form a disc-shaped structure 71b.

[0063] Next, for Figure 4B The structure 71b shown is fired to obtain Figure 4C The ceramic substrate 72a is shown. The firing temperature of the structure 71b is, for example, 1,600°C. For example, suppose that the via conductors 54 and 56, which serve as vias 23a and 23b, are made solely of molybdenum. In this case, unless the via conductors 54 and 56 are fired under pressure, a sufficiently high adhesion between the vias and the ceramic cannot be obtained. On the other hand, when the via conductors 54 and 56, which serve as vias 23a and 23b, contain molybdenum as the main component and are supplemented with nickel oxide, aluminum oxide, and silicon dioxide, a sufficiently high adhesion between the vias and the ceramic can be obtained even when the via conductors 54 and 56 are fired at atmospheric pressure. Compared to the case of firing the via conductors 54 and 56 under pressure, the operating cost can be reduced by firing the via conductors 54 and 56 at atmospheric pressure.

[0064] In this process, sintering the electrical conductor pattern 55 yields the electrostatic electrode 22, sintering the via conductors 54 and 56 yields vias 23a and 23b, and sintering the electrical conductor pattern 57 yields the heating element 24. The electrostatic electrode 22 and the vias 23a and 23b are electrically connected to each other. That is, the electrostatic electrode 22, the vias 23a and 23b, and the heating element 24 are embedded within... Figure 4C In the ceramic substrate 72a shown.

[0065] Next, the ceramic substrate 72a undergoes various processing steps to complete the electrostatic chuck 20. For example, the top and bottom surfaces of the ceramic substrate 72a are ground to form mounting surfaces and mating surfaces. Furthermore, [the process is described in the original text, but the translation is incomplete]. Figure 2 The lifting pin opening portion 12 is shown.

[0066] The substrate fixing device and the like will be described in more detail below with reference to embodiments and comparative examples. However, this disclosure is not limited to these embodiments.

[0067] [Example 1, Comparative Example 1]

[0068] First, such as Figure 5AAs shown, two green wafers 300 are prepared, each made of alumina ceramic material but without any sintering aids. Then, through-holes 301 are formed at predetermined locations on the green wafers 300, and conductive paste is filled into the through-holes 301 by screen printing, thereby forming vias 302, wherein the amount of alumina powder added to the conductive paste is 11.0% by weight relative to the amount of molybdenum powder. Next, conductive paste is applied to the opposite sides of each green wafer 300 by screen printing, thereby forming pads 303 and 304 electrically connected to the vias 302.

[0069] Next, as Figure 5B As shown, green wafers 300 are stacked to make the pads conductive to each other, and green wafers 300, vias 302, and pads 303 and 304 are simultaneously fabricated under atmospheric pressure. Next, as... Figure 5C As shown, the pads formed on the top and bottom surfaces of the laminate of the green wafer 300 are removed by grinding. Thus, the sample 300A according to Comparative Example 1 was obtained.

[0070] Next, through with Figures 5A to 5C The same method was used to prepare sample 300B according to Example 1, except that the conductive paste contained, relative to the amount of molybdenum powder, 0.5% by weight of nickel oxide powder, 11.0% by weight of aluminum oxide powder, and 2.0% by weight of silicon dioxide powder.

[0071] Figure 6A The SEM image of sample 300A is shown. Figure 6B SEM images of sample 300B are shown. In sample 300A, the upper part of the electrical conductor in one of the vias 302 (within portion A enclosed by the dashed line) is defective. Therefore, it can be inferred that the molybdenum sintering was insufficient, resulting in poor adhesion between the electrical conductor in the via 302 and the ceramic, thus causing defects during grinding. On the other hand, in sample 300B, the electrical conductors in each via 302 are not defective. Therefore, it can be inferred that the molybdenum is sufficiently sintered, thereby enhancing the adhesion between the electrical conductor in the via 302 and the ceramic.

[0072] Figure 7 The EPMA analysis results of the cross section of specimen 300A are shown. Figure 8 The EPMA analysis results for the cross-section of specimen 300B are shown. From Figure 7 It can be seen that the conductive paste in sample 300A does not contain silicon dioxide. Therefore, it naturally does not contain Si. On the other hand, from Figure 8It can be confirmed that in sample 300B, the Si component exists in both the electrical conductor in the via 302 and the ceramic (fired green sheet 300), and in particular only in the vicinity of the boundary in the ceramic (within 20 μm of the ceramic side including boundary B).

[0073] Therefore, the Si component exists only within a range of 20 μm below the ceramic side including boundary B, and does not diffuse beyond this range. This reduces the likelihood of ceramic property degradation.

[0074] [Example 2, Comparative Example 2]

[0075] A green wafer was prepared in which the ceramic material was made of alumina and contained no sintering aids. Then, pads were formed on each surface of the green wafer using a conductive paste, in which nickel oxide powder was added at 0.5 wt%, alumina powder at 2.0 wt%, and silicon dioxide powder at 2.0 wt%, relative to the amount of molybdenum powder. After simultaneously firing the green wafer and pads at atmospheric pressure, the pads were removed by grinding to expose the ceramic. As a result, a sample 300C according to Example 2 was obtained.

[0076] In addition, a green sheet was prepared in which the ceramic material was made of alumina and contained sintering aids. Then, pads were formed on each surface of the green sheet using a conductive paste, wherein the conductive paste contained 0.5 wt% nickel oxide powder, 2.0 wt% alumina powder, and 2.0 wt% silicon dioxide powder, relative to the amount of molybdenum powder. After simultaneously firing the green sheet and pads at atmospheric pressure, the pads were removed by grinding to expose the ceramic. As a result, sample 300D according to Comparative Example 2 was obtained.

[0077] Figure 9A These are the XRD analysis results of the ceramic portion exposed through grinding in sample 300C. Figure 9A It can be confirmed that a crystalline phase of mullite, sillimanite, or a mixture of both was formed in the exposed ceramic portion of the sample 300C according to Example 2.

[0078] The Si component of silica added to the conductive paste can be divided into Si component retained in the electrical conductor after firing and Si component diffused to the ceramic side. Since the Si component diffused from the electrical conductor to the ceramic side is consumed, a composite oxide layer of Al and Si is formed near the boundary between the electrical conductor and the ceramic, thus preventing Si component from diffusing into the interior of the ceramic. It can be considered that the Al and Si composite oxide layer formed near the boundary between the electrical conductor and the ceramic largely contributes to improving the adhesion between the electrical conductor and the ceramic.

[0079] Furthermore, the chemical formula of mullite is 3Al2O3·2SiO2(Al6Si2O) 13 The chemical formula of sillimanite is Al2O3·SiO2 (Al2SiO5). The range of the Al and Si composite oxide layer can be controlled to some extent by adjusting the amount of alumina and silica added to the conductive paste.

[0080] Figure 9B The XRD analysis results of the exposed ceramic portion of sample 300D after grinding are shown. Figure 9B It can be seen that in sample 300D according to Comparative Example 2, no crystalline phases of mullite and sillimanite were formed.

[0081] Therefore, in the electrostatic chuck 20 of the substrate fixing device 1, the substrate body 21 is made of ceramic containing alumina (Al2O3). In addition, the vias 23a and 23b are each sintered bodies containing molybdenum (Mo) as the main component and with added nickel oxide (NiO), alumina (Al2O3) and silicon dioxide (SiO2).

[0082] By adding nickel oxide to the conductive paste used as vias 23a and 23b, the sinterability of molybdenum in the electrical conductors forming vias 23a and 23b is improved. Furthermore, by adding alumina and silicon dioxide to the conductive paste used as vias 23a and 23b, the adhesion between the ceramic forming the substrate body 21 and the molybdenum is improved. Therefore, no sintering aids are required, thereby reducing the possibility of property degradation of the ceramic constituting the substrate body 21.

[0083] Furthermore, molybdenum and nickel oxide components are not present in the ceramic forming the substrate body 21, but only in the vias, while alumina and silicon dioxide components are present in both the ceramic forming the substrate body 21 and the vias. Specifically, in the ceramic forming the substrate 21, silicon dioxide is only present within a 20 μm range from the boundary between the ceramic forming the substrate body 21 and the vias, and a composite oxide layer of aluminum and silicon dioxide (mullite layer, sillimanite layer, or a mixture of mullite and sillimanite layers) is formed within this range. Therefore, Si components do not diffuse beyond the composite oxide layer. Thus, the possibility of degradation of the properties of the ceramic forming the substrate body 21 is reduced. The extent of the composite oxide layer can be changed by the amount of alumina and silicon dioxide added to the conductive paste.

[0084] Furthermore, the electrostatic electrode 22 is preferably a sintered body containing tungsten (W) as the main component and with the addition of nickel oxide (NiO), aluminum oxide (Al2O3) and silicon dioxide (SiO2).

[0085] By adding nickel oxide to the conductive paste that will be used as the electrostatic electrode 22, the sinterability of tungsten in the electrical conductor forming the electrostatic electrode 22 is improved. Furthermore, by adding alumina and silicon dioxide to the conductive paste that will be used as the electrostatic electrode 22, the adhesion between the ceramic forming the substrate body 21 and the tungsten is improved. Therefore, no sintering aids are required, thereby reducing the possibility of property degradation of the ceramic forming the substrate body 21.

[0086] The purity of alumina in the ceramic forming the substrate body 21 is preferably 99.5% or higher. As a result, the temperature dependence of the insulation resistance in the substrate body 21 is very small, which makes it possible to suppress the decrease of insulation resistance with increasing temperature.

[0087] The relative density of the ceramic forming the substrate body 21 is preferably 97% or higher compared to alumina. This substrate body 21 has a relatively small number of pores on its surface and inside. These pores can affect the adsorption of the substrate body 21. Therefore, a substrate body 21 with a high relative density is preferred in terms of its characteristics as a substrate fixing device 1.

[0088] (Second Implementation Plan)

[0089] In the second embodiment, an example of a semiconductor device package having the ceramic substrate described in the first embodiment is shown. Figure 10 A cross-sectional view of a semiconductor device package according to a second embodiment is shown. Figure 11 A plan view of a semiconductor device package according to a second embodiment is shown.

[0090] like Figure 10 As shown, the semiconductor device package 100 has a ceramic substrate 110, a heat-radiating plate 150 and an external connection terminal 160, and the heat-radiating plate 150 is brazed to the ceramic substrate 110.

[0091] The ceramic substrate 110 includes a plurality (four in this embodiment) of ceramic substrate materials 111, 112, 113, and 114 stacked on top of each other, wiring patterns 121, 122, 123, and 124, and vias 132, 133, and 134 penetrating the ceramic substrate materials 112, 113, and 114. Via 132 connects wiring patterns 121 and 122 to each other, via 133 connects wiring patterns 122 and 123 to each other, and via 134 connects wiring patterns 123 and 124 to each other. In the ceramic substrate 110, ceramic substrate materials 111 to 114 constitute the substrate body.

[0092] like Figure 10 and Figure 11As shown, a cavity 170 is provided in the ceramic substrate 110, penetrating the central portion of the ceramic substrate materials 112, 113, and 114, so that a semiconductor device 200 can be mounted within the cavity 170. A wiring pattern 121 is provided on the top surface of the ceramic substrate material 112 in a manner that surrounds the cavity 170. An opening 111X is formed in the ceramic substrate material 111 to expose the wiring pattern 121.

[0093] The ceramic substrate materials 111 to 114 are made of ceramic containing alumina, and the wiring patterns 121 to 124 are each made of a sintered body of a conductor paste containing tungsten as a main component, and also containing nickel oxide, alumina, and silicon dioxide. Furthermore, the vias 132 to 134 are each a sintered body of a conductor paste containing molybdenum as a main component, and also containing nickel oxide, alumina, and silicon dioxide. The ceramic substrate 110 can be manufactured using the same manufacturing method as the electrostatic chuck 20 according to the first embodiment.

[0094] In the semiconductor device package 100, a semiconductor element 200 is mounted on a heat-radiating plate 150. The pads of the semiconductor element 200 are electrically connected to the wiring pattern 121 of the ceramic substrate 110 via bonding wires or the like. As a result, the semiconductor element 200 is connected to external connection terminals 160 via wiring patterns 121 to 124 and vias 132 to 134.

[0095] In such a semiconductor device package 100, a ceramic substrate 110 including wiring patterns 121 to 124 and vias 132 to 134 can be obtained in the same manner as in the first embodiment without degrading the properties of the ceramic substrate materials 111 to 114, which form the substrate body. In the ceramic substrate 110, the adhesion between the ceramic substrate materials 111 to 114 and the wiring patterns 121 to 124, the adhesion between the ceramic substrate 111 to 114 and the vias 132 to 134, and the adhesion between the wiring patterns 121 to 124 and the vias 132 to 134 can be improved.

[0096] Although the preferred embodiments have been described in detail above, this disclosure is not limited to the above embodiments, and various modifications and substitutions may be made to the above embodiments without departing from the scope of the claims.

[0097] For example, in the first embodiment, the layout of the components or parts included in the substrate fixing device can be appropriately changed.

[0098] Furthermore, in the first embodiment, a heating element 24 can be disposed between the electrostatic chuck 20 and the base plate 10. Alternatively, the heating element 24 can be disposed inside the base plate 10. Alternatively, the heating element 24 can be attached to the outside of the electrostatic chuck.

[0099] Furthermore, the substrate fixing device according to the first embodiment is used in semiconductor manufacturing equipment. The semiconductor manufacturing equipment is, for example, a dry etching equipment (e.g., a parallel-plate reactive ion etching (RIE) equipment).

[0100] In addition to semiconductor wafers (such as silicon wafers), glass substrates used in the manufacturing process of liquid crystal panels and the like can be used as adsorption objects of the substrate fixing device according to the first embodiment.

Claims

1. A ceramic substrate, comprising: substrate body; An electrical conductor layer embedded in the substrate body; as well as The via is embedded in the substrate body and electrically connected to the electrical conductor layer. in: The substrate body is made of ceramic containing alumina with a purity of 99.5% or higher without sintering aids; and The via is formed from a sintered body of an electrical conductor paste, wherein the electrical conductor paste contains molybdenum as the main component, and also contains nickel oxide, aluminum oxide, and silicon dioxide. In the electrical conductor paste, the content of nickel oxide is from 0.2% to 1.0% by weight relative to molybdenum, the content of aluminum oxide is from 2.0% to 20.0% by weight relative to molybdenum, and the content of silicon dioxide is from 0.2% to 3.0% by weight relative to molybdenum. The substrate body contains silicon, but excludes molybdenum and nickel. The silicon contained in the substrate body exists only within a 20 μm range from the boundary between the substrate body and the via. A composite oxide layer comprising oxygen, aluminum, and silicon is formed within a 20 μm range from the boundary between the substrate body and the via.

2. The ceramic substrate according to claim 1, wherein... In the electrical conductor paste, The molybdenum has an average particle size of 0.5 μm to 3.0 μm. The average particle size of the nickel oxide is 5.0 μm to 15.0 μm. The alumina has an average particle size of 0.1 μm to 4.0 μm, and The average particle size of the silica is from 0.1 μm to 12.0 μm.

3. The ceramic substrate according to claim 1, wherein... The composite oxide layer comprises at least one of a mullite layer and a sillimanite layer.

4. The ceramic substrate according to claim 1, wherein... The relative density of the substrate body to the alumina is 97% or higher.

5. The ceramic substrate according to claim 1, wherein... The alumina in the substrate body has an average particle size of 1.0 μm to 3.0 μm.

6. The ceramic substrate according to claim 1, wherein... The electrical conductor layer is made from a sintered body of an electrical conductor paste, wherein the electrical conductor paste contains tungsten as the main component and also contains nickel oxide, aluminum oxide and silicon dioxide.

7. The ceramic substrate according to claim 1, wherein... The ceramic substrate is configured as an electrostatic chuck for adsorbing target objects, and The electrical conductor layer is an electrostatic electrode.

8. A semiconductor device package comprising the ceramic substrate according to claim 1.

9. A substrate fixing device, comprising: Base plate; as well as A ceramic substrate according to claim 7 is mounted on one side of the base plate.

10. A method for manufacturing a ceramic substrate, wherein the ceramic substrate includes a substrate body, an electrical conductor layer embedded in the substrate body, and vias embedded in the substrate body and electrically connected to the electrical conductor layer. The method includes: A first conductive paste with a predetermined pattern is formed on a green sheet, wherein the green sheet is made of a mixture of alumina without sintering aids and organic materials; The through-holes formed in the green sheet are filled with a second conductive paste, wherein the second conductive paste contains molybdenum as a main component, and also contains nickel oxide, aluminum oxide, and silicon dioxide; and The green sheet, the first conductive paste, and the second conductive paste are fired to form the substrate body, the electrical conductor layer, and the vias. In the second conductive paste, the content of nickel oxide is from 0.2% to 1.0% by weight relative to molybdenum, the content of aluminum oxide is from 2.0% to 20.0% by weight relative to molybdenum, and the content of silicon dioxide is from 0.2% to 3.0% by weight relative to molybdenum. The substrate body is made of ceramic containing alumina with a purity of 99.5% or higher without sintering aids. The substrate body contains silicon, but excludes molybdenum and nickel. The silicon contained in the substrate body exists only within a 20 μm range from the boundary between the substrate body and the via. A composite oxide layer comprising oxygen, aluminum, and silicon is formed within a 20 μm range from the boundary between the substrate body and the via.

Images