JP2019165126A - Ceramic substrate structure and manufacturing method thereof - Google Patents

Abstract

To provide a ceramic substrate structure capable of suppressing embrittlement of a power supply pad in a high temperature atmosphere.SOLUTION: A ceramic substrate structure 10 comprises: a ceramic base 11 in which a concave part 11c is formed in a lower surface 11b, and which is formed by a ceramic; a conductor 12 built in the ceramic base 11; a power supply pad 13 which is electrically connected to the conductor 12, embedded in the ceramic base 11, and formed by a first metal in which a surface opposite to a conductor 11 defines at least one part of a bottom surface of the concave part 11c; a power supply terminal 17 for supplying a power to a conductor 12 via the power supply pad 13; and a first metal layer 14 that is exposed in an outer part so as to cover at least one part of the surface opposite to the conductor 12 of the power supply pad 17, and is made of a second metal. A standard generation freely energy at 650°C in an oxidation reaction between the second metal and oxygen is smaller than the standard generation freely energy at 650°C in the oxidation reaction between the first metal and oxygen, and is larger than -250 Kcal/mol.SELECTED DRAWING: Figure 2C

Description

  The present invention relates to a ceramic substrate structure, and more particularly to a ceramic substrate structure used in a substrate heating apparatus in a semiconductor manufacturing apparatus and a method for manufacturing the same.

  In an electrostatic chuck or susceptor used to hold a wafer in a semiconductor manufacturing apparatus, an external power source is connected to a conductor embedded in a base made of a ceramic sintered body via a power supply terminal. In this case, a terminal connected to an external power source is joined to a power supply pad electrically connected to the conductor. The power supply pad is made of tungsten or molybdenum, and is embedded in the ceramic sintered body by being in contact with the power supply terminal and being fired while being embedded in the ceramic.

  Patent Document 1 discloses a technique for increasing the bonding strength of a bonding layer that bonds a power supply member (power supply terminal) and an electrode terminal (power supply pad).

Japanese Patent No. 5968651

  However, recently, a ceramic heater made of aluminum nitride (AlN) or the like has been developed for use at a high temperature of about 650 ° C. to 800 ° C. for a long time. Under such a high-temperature environment, a small amount of oxygen is present even in the air or in an inert atmosphere, so that the power supply pad is oxidized and weakened. Such weakening causes problems such as breakage and peeling of the power supply pad.

  Then, an object of this invention is to provide the ceramic substrate structure which can aim at suppression of weakening of the electric power feeding pad in high temperature atmosphere, and its manufacturing method.

  The ceramic substrate structure of the present invention has a substrate mounting surface on which a substrate is mounted, and a concave portion is formed on a surface opposite to the substrate mounting surface, the ceramic substrate made of ceramics, and the ceramic substrate A power supply made of a first metal that is electrically connected to the conductor, embedded in the ceramic base, and whose surface opposite to the conductor defines at least part of the bottom surface of the recess. A pad, a power supply terminal for supplying power to the conductor via the power supply pad, and at least a part of the surface of the power supply pad opposite to the conductor, and exposed to the outside, and made of a second metal. A standard generation free energy at 650 ° C. in the oxidation reaction between the second metal and oxygen is a standard generation at 650 ° C. in the oxidation reaction between the first metal and oxygen. Less than free energy, and, being greater than -250Kcal / mol. In this specification, the standard free energy of formation is a value per 1 mol of oxygen.

  According to the ceramic substrate structure of the present invention, since the standard free energy of formation is in the above relationship, the oxidation of the metal layer proceeds prior to the oxidation of the power supply pad. Slower than the conventional one that does not exist. Thereby, it becomes possible to extend the lifetime of the ceramic substrate structure due to the brittleness of the power supply pad.

  In the ceramic substrate structure of the present invention, the standard free energy of formation at 650 ° C. in the oxidation reaction between the second metal and oxygen is preferably greater than −150 Kcal / mol.

  In this case, furthermore, since the standard free energy of formation is in the above relationship, the oxidation of the metal layer proceeds more reliably before the oxidation of the power supply pad. Slower than the ones. Thereby, it becomes possible to further extend the lifetime of the ceramic base material structure 10 by embrittlement of the power supply pad. Note that when the first metal is tungsten or molybdenum and the second metal is chromium, the standard free energy of formation satisfies the above relationship.

  Further, in the ceramic substrate structure of the present invention, the ceramic substrate structure includes an intermediate body that is located between the power supply pad and the power supply terminal, is made of a third metal, and the surface exposed to the outside is covered with the fourth metal, The standard free energy of formation at 650 ° C. in the oxidation reaction of the fourth metal and oxygen is smaller than the standard free energy of formation at 650 ° C. in the oxidation reaction of the first metal and oxygen, and from −250 Kcal / mol. Larger is preferred.

  In this case, since the standard free energy of formation is in the above relationship, the oxidation of the metal layer proceeds prior to the oxidation of the power supply pad. Therefore, the oxidation start of the intermediate is covered with the fourth metal covering the intermediate. Slower compared to not. Thereby, it becomes possible to extend the lifetime of the ceramic substrate structure due to the embrittlement of the intermediate.

  The method for manufacturing a ceramic substrate structure according to the present invention includes a substrate mounting surface on which a substrate is mounted, a conductor and a power supply pad made of a first metal that is electrically connected to the conductor, and is made of ceramic. A step of preparing a base, a step of forming a recess on a surface opposite to the base mounting surface to expose a part of the power supply pad, and the exposed surface of the power supply pad made of a second metal. A step of covering with a metal layer, and a step of electrically connecting a power supply terminal to the power supply pad, wherein the standard free energy of formation at 650 ° C. in the oxidation reaction between the second metal and oxygen is the first metal It is characterized by being smaller than the standard free energy of formation at 650 ° C. in the oxidation reaction between oxygen and oxygen, and larger than −250 Kcal / mol.

  According to the method for manufacturing a ceramic substrate structure of the present invention, since the standard free energy of formation is in the above relationship, the oxidation of the metal layer proceeds before the oxidation of the power supply pad. It is slower than the conventional one in which no metal layer is present. Thereby, it becomes possible to extend the lifetime of the ceramic substrate structure due to the brittleness of the power supply pad.

  In the method for manufacturing a ceramic substrate structure according to the present invention, the method includes a step of preparing an intermediate body made of a third metal and having a surface covered with a fourth metal, the intermediate between the power supply pad and the power supply terminal. By fixing the body, the power supply pad and the power supply terminal are electrically connected, and the standard free energy of formation at 650 ° C. in the oxidation reaction between the fourth metal and oxygen is the first metal and oxygen. It is preferably smaller than the standard free energy of formation at 650 ° C. in the oxidation reaction with and greater than −250 Kcal / mol.

  In this case, since the standard free energy of formation is in the above relationship, the oxidation of the metal layer proceeds prior to the oxidation of the power supply pad. Therefore, the oxidation start of the intermediate is covered with the fourth metal covering the intermediate. Slower compared to not. Thereby, it becomes possible to extend the lifetime of the ceramic substrate structure due to the embrittlement of the intermediate.

1 is a schematic longitudinal sectional view of a ceramic substrate structure according to an embodiment of the present invention. It is a schematic longitudinal cross-sectional view explaining the manufacturing method of the ceramic substrate structure which concerns on embodiment of this invention, and shows the state by which the electric power feeding pad is embed | buried in a base | substrate. It is a schematic longitudinal cross-sectional view explaining the manufacturing method of the ceramic substrate structure which concerns on embodiment of this invention, and shows the state which drilled the terminal hole. It is a schematic longitudinal cross-sectional view explaining the manufacturing method of the ceramic substrate structure which concerns on embodiment of this invention, and shows the state which brazed the electric power feeding terminal to the electric power feeding pad via the intermediate body. The schematic longitudinal cross-sectional view of the ceramic substrate structure which concerns on another embodiment of this invention.

  A ceramic substrate structure 10 according to an embodiment of the present invention will be described.

  As shown in FIGS. 1 and 2C, the ceramic substrate structure 10 includes a ceramic substrate 11, a conductor 12, a power supply pad 13, a first metal layer 14, a buffer member 15, a second metal layer 16, a power supply terminal 17, and A brazing material layer 18 is provided.

  The ceramic substrate structure 10 is used as a heater, electrostatic chuck or susceptor for holding or heating a substrate such as a semiconductor wafer in a semiconductor manufacturing apparatus. The first metal layer 14 corresponds to the metal layer of the present invention, and the buffer member 15 corresponds to the intermediate body of the present invention.

  The ceramic substrate 11 is made of ceramic. As a material constituting the ceramic substrate 11, a ceramic sintered body such as aluminum nitride, alumina, silicon carbide, or silicon nitride can be used. In addition, you may add an additive suitably.

  The ceramic substrate 11 has an upper surface 11a serving as a substrate mounting surface 11a on which a substrate W such as a semiconductor wafer is mounted, and a lower surface 11b opposite to the upper surface 11a serving as a surface connected to an external power source.

  A recess 11 c is formed on the lower surface 11 b of the ceramic substrate 11. The recess 11 c is formed to expose a part of the power supply pad 13 from the lower surface 11 a of the ceramic substrate 11. The recess 11c is formed in a polygonal shape such as a circle, a triangle, or a quadrangle in plan view. The power supply pad 13, the first and second metal layers 14, 16 and the buffer member 15 are disposed in the recess 11c.

  The conductor 12 is built in the ceramic substrate. The shape of the conductor 12 is not particularly limited, and may be any shape such as a plate shape, a net shape, a lattice shape, a perforated surface shape, or a comb tooth shape. The thickness and the wire diameter of the conductor 12 are not particularly limited. The conductor 12 functions as a heating resistor or an adsorption electrode. The conductor 12 may be composed of a plurality of layers separated in the vertical direction.

  The material of the conductor 12 is desirably molybdenum (Mo), tungsten (W), or an alloy containing these as a main component. Note that an alloy mainly composed of molybdenum and tungsten generally has a total content of molybdenum and tungsten of 50% by weight or more, preferably 70% by weight or more, more preferably 80% by weight. % Or more.

  The power supply pad 13 is electrically connected to the conductor 12, is embedded in the ceramic base 11, and is made of a first metal. Here, the conductor 12 and the power feeding pad 13 are integrated by firing.

  The surface of the power supply pad 13 opposite to the conductor 12 defines at least a part of the bottom surface of the recess 11c. Here, the central portion of the lower surface of the power supply pad 13 is exposed downward and is a part of the bottom surface of the recess 11c.

  The shape of the power supply pad 13 is not particularly limited, but is preferably a plate shape. The top view shape of the power supply pad 13 is not particularly limited, but is preferably a polygonal shape such as a triangular shape or a quadrangular shape or a circular shape.

  The material of the conductor 12 and the power supply pad 13 is approximately the same as that of the material of the ceramic base 11 such as aluminum nitride, alumina, etc. in consideration of firing in an integrated state with the ceramic constituting the ceramic base 11. It is desirable to be a high melting point metal having thermal expansibility.

  The material of the conductor 12 and the power supply pad 13 may be the same or the same as the main component, but the main component may be different such that the conductor 12 is molybdenum and the power supply pad 13 is tungsten.

  The first metal layer 14 covers at least part of the surface of the power supply pad 13 opposite to the conductor 12 and is exposed to the outside, and is made of a second metal. It is preferable that the portion exposed to the recess 11 c of the power supply pad 13 is entirely covered with the first metal layer 14 so that the power supply pad 13 is not partially exposed to the outside.

  Here, the standard free energy of formation at 650 ° C. in the oxidation reaction of the second metal and oxygen is smaller than the standard free energy of formation at 650 ° C. in the oxidation reaction of the first metal and oxygen, and −250 Kcal / mol. Greater than. For example, when the first metal constituting the conductor 12 is tungsten or molybdenum or an alloy containing these as a main component, the second metal constituting the first metal layer 14 is chromium (Cr), titanium (Ti). Zirconium (Zr), aluminum (Al), or an alloy containing these as a main component.

  However, the standard free energy of formation at 650 ° C. in the oxidation reaction between the second metal and oxygen is preferably larger than −150 Kcal / mol. An example of such a second metal is chromium (Cr).

  The buffer member 15 is sandwiched vertically between the first metal layer 14 formed on the upper surface of the power supply pad 13 and the power supply terminal 17 and is made of a third metal. The buffer member 15 is entirely covered with the second metal layer 16. Here, the buffer member 15 covered with the second metal layer 16, the first metal layer 14, and the power supply terminal 17 are fixed by brazing, and the brazing material layer 18 is joined therebetween. Further, the brazing filler metal layer 18 may fill a part of the recess 11c. Note that the upper surface, the lower surface, or the upper and lower surfaces of the buffer member 15 may not be covered with the second metal layer 16. The second metal layer 16 is made of a fourth metal.

  Here, the standard free energy of formation at 650 ° C. in the oxidation reaction of the fourth metal and oxygen is smaller than the standard free energy of formation at 650 ° C. in the oxidation reaction of the third metal and oxygen, and −250 Kcal / mol. Greater than. For example, when the third metal constituting the buffer member 15 is tungsten or molybdenum, the fourth metal constituting the second metal layer 16 is chromium (Cr), titanium (Ti), zirconium (Zr), aluminum ( Al) or an alloy mainly composed of these.

  However, the standard free energy of formation at 650 ° C. in the oxidation reaction between the fourth metal and oxygen is preferably greater than −150 Kcal / mol. An example of such a fourth metal is chromium (Cr).

  The power supply terminal 17 is electrically connected through the first and second metal layers 14, 16, the buffer member 15, and the brazing material layer 18 in order to supply power to the conductor 12 through the power supply pad 13.

  The ceramic substrate structure 10 further includes a cylindrical shaft (cylindrical support) 19 connected to the lower surface 11 b of the ceramic substrate 11. The shaft 19 has a cylindrical portion 19a located at the central portion in the vertical direction and cylindrical enlarged diameter portions 19b having a diameter larger than that of the cylindrical portion 19a at both upper and lower ends.

  The lower surface 11a of the ceramic substrate 11 and the upper end surface of the shaft 19 are bonded by diffusion bonding or solid phase bonding using a bonding material such as ceramics or glass. The ceramic substrate 11 and the shaft 19 may be connected by screwing or brazing.

  A method for manufacturing the ceramic substrate structure 10 according to the embodiment of the present invention will be described. However, the manufacturing method of the ceramic substrate structure 10 according to the embodiment of the present invention is not limited to this.

  First, as shown in FIG. 2A, a step of preparing a ceramic substrate 11 in which a conductor 12 and a power supply pad 13 electrically connected to the conductor 12 are incorporated is performed. For example, it is preferable to manufacture by a method in which the conductor 12 and the power supply pad 13 are embedded in a ceramic body made of ceramic powder and subjected to hot press firing.

  The conductor 12 and the power supply pad 13 may be joined in advance by welding, caulking, or the like before sintering. Further, powders of the same material as these may be sandwiched between the conductor 12 and the power supply pad 13, and in this case, they are integrated during firing.

  Moreover, you may manufacture the ceramic base | substrate 11 by which the conductor 12 and the electric power feeding pad 13 were embed | buried inside by the method of joining and integrating the several ceramic sintered body which baked separately by heat processing.

  Next, as shown in FIG. 2B, a step of drilling the ceramic substrate 11 from the lower surface 11b by an arbitrary hole drilling method using a machining center or the like for the recess 11c for arranging the power supply terminal 17 is performed. The recess 11c is formed so as to remove the ceramic substrate 11 until a part of the lower surface of the power supply pad 13 is exposed. At this time, it is desirable that the inner diameter of the recess 11 c is set to be smaller than the outer diameter of the power supply pad 13, and the bottom surface of the recess 11 c is configured only by the power supply pad 13.

  As shown in FIG. 2C, the power supply terminal 17 is for supplying power to the conductor 12 from the external power source through the power supply pad 13, and the buffer member 15 and the brazing material, one end of which is covered by the second metal layer 16. Bonded via the layer 18, the other end protrudes from the ceramic substrate 11 to the outside.

  Although the shape of the buffer member 15 and the power supply terminal 17 is not particularly limited, it is most preferable that the buffer member 15 and the power supply terminal 17 have a cylindrical shape in consideration of the connection with the power supply pad 13. However, the shape of the buffer member 15 and the power supply terminal 17 may be a prism, a polygonal column, an elliptical column, or the like, and may have a protrusion or a recess.

  The power supply terminal 17 is made of nickel (Ni), titanium (Ti), copper (Cu), or an alloy containing these as main components. In addition, although the alloy which has nickel, titanium, and copper as a main component generally points out that the total content rate of nickel, titanium, and copper is 50 weight% or more, Preferably it is 70 weight% or more, More preferably Is 80% by weight or more. Also, a low thermal expansion alloy such as Kovar can be suitably used for the power supply terminal 17.

  When the power supply terminal 17 is made of nickel, titanium, or an alloy containing these as a main component, the power supply terminal 17 is preferable because of its excellent corrosion resistance. In addition, when the power supply terminal 17 is made of copper or an alloy containing copper as a main component, it is ductile compared to the case of being made of nickel or titanium, so that stress is generated in the connection between the power supply terminal 17 and the power supply line. However, there is an advantage that the stress is easily relaxed.

  The buffer member 15 covered with the second metal layer 16, the first metal layer 14, and the power supply terminal 17 are joined by brazing. As the brazing material, for example, Ag-based brazing or Au-based brazing is used, and the brazing temperature is 800 ° C. or more for Ag brazing and 1000 ° C. or more for Au brazing.

  According to the ceramic substrate structure 10 described above, since the standard free energy of formation is in the above relationship, the oxidation of the first metal layer 14 is the oxidation of the power supply pad 13 as can be seen from the examples and comparative examples described later. Since the oxidation of the second metal layer 16 proceeds earlier than the oxidation of the buffer member 15, the start of oxidation of the power supply pad 13 and the buffer member 15 is delayed. Accordingly, it is possible to extend the life of the ceramic base structure 10 due to the power supply pad 13 or the buffer member 15 becoming brittle.

  The ceramic substrate structure and the manufacturing method thereof according to the present invention are not limited to the above-described embodiments. For example, as shown in FIG. 3, the buffer member 15 and the second metal layer 16 covering the buffer member 15 do not exist, and the power supply terminal 17 is directly formed on the first metal layer 14 via the brazing material layer 18. It may be connected. Further, the shaft 19 may not be provided.

  In Examples 1 to 8 and Comparative Examples 1 and 2, the ceramic substrate structure 10 that does not include the shaft 19 and functions as a ceramic heater was produced.

(Example 1)
A mixed powder of 97% by weight of aluminum nitride powder and 3% by weight of yttria powder was uniaxially pressed to produce a molded body having a diameter of 340 mm and a thickness of 5 mm as the first layer.

  Then, a conductor 12 made of molybdenum mesh having a diameter of 290 mm, a wire diameter of 0.1 mm, and an opening of 50 mesh and functioning as an internal electrode was placed on the molded body of the first layer. Further, a power supply pad 13 made of a tungsten disk having a diameter of 10 mm and a thickness of 0.5 mm was placed on the conductor 12. Further, after filling the mixed powder thereon, uniaxial pressing was performed to produce a second layer of the molded body. The thickness of the second layer was 10 mm.

  Then, a conductor 12 made of a molybdenum mesh having a wire diameter of 0.1 mm, an aperture of 50 mesh, and a resistance value adjusted to 4Ω, and functioning as a heater electrode is placed on the second layer formed body. did. Further, a power supply pad 13 made of a tungsten disk having a diameter of 10 mm and a thickness of 0.5 mm was placed on the conductor 12. Furthermore, after filling the said mixed powder on it, it uniaxially pressurized and produced the 3rd layer of the molded object. The thickness of the third layer was 10 mm.

  The molded body thus formed into three layers was hot-press fired at a pressure of 10 MPa, a firing temperature of 1850 ° C., and a firing time of 2 hours. As a result, a ceramic substrate 11 made of a disk-shaped ceramic fired body having a diameter of 340 mm and a thickness of 25 mm was obtained.

  Then, the upper and lower surfaces of the obtained ceramic substrate 11 were ground so that the distance between the upper surface 11a and the conductor 12 functioning as a heater electrode was 0.3 mm and the surface roughness Ra was 0.4 μm. Thereafter, the recess 11c was drilled with a diameter of 5 mm so that the power supply pad 13 was exposed.

  The first metal layer 14 was a metal layer made of chromium (Cr) having a thickness of 10 μm. A sheet-like brazing material having a BAu-4 gold brazing composition was disposed on the lower surface of the first metal layer 14. Below that, the buffer member 15 covered with the second metal layer 16 was arranged, and below that, the same brazing material as the brazing material was arranged. The buffer member 15 is a disc-shaped body made of tungsten having a diameter of 4.5 mm and a thickness of 2 mm. The buffer member 15 is plated by plating the entire outer periphery of the buffer member 15 to a thickness of 10 μm. Covered with a second metal layer 16.

  Then, the power supply terminal 17 was disposed using the same brazing material as the brazing material, and brazing was performed in a vacuum atmosphere at a brazing temperature of 1050 ° C., thereby completing the ceramic base structure 10. The power supply terminal 17 was a cylindrical body made of nickel and having a diameter of 4 mm and a length of 200 mm.

  In the ceramic substrate structure 10 described above, heat was generated from the conductor 12 by supplying a current to the power supply terminal 17 from a power source (not shown).

  In the condition A, the state where the temperature of the upper surface 11a was maintained at 650 ° C. was maintained for 1000 hours. Thereafter, the experimenter visually confirmed the presence or absence of wobbling of the power supply terminal 17 and the abnormal connection state, but no abnormality was found. Moreover, the fluctuation | variation from the initial stage of the resistance value of the conductor 12 was less than 10%, and the fluctuation | variation was small.

  In the condition B, the state where the temperature of the upper surface 11a was maintained at 800 ° C. was maintained for 1000 hours. Thereafter, the experimenter visually confirmed the presence or absence of wobbling of the power supply terminal 17 and the abnormal connection state, but no abnormality was found. Moreover, the fluctuation | variation from the initial stage of the resistance value of the conductor 12 was less than 10%, and the fluctuation | variation was small.

(Examples 2, 7, and 8)
Example 2 was the same as Example 1 except that the first metal layer 14 and the second metal layer 16 were formed by PVD (sputtering). Example 7 was the same as Example 1 except that the buffer member 15 was made of Kovar (KOV). Example 8 was the same as Example 1 except that the power supply pad 13 and the buffer member 15 were made of molybdenum (Mo).

  In Examples 2, 7, and 8, as in Example 1, the connection state of the power supply terminal 17 was good under the conditions A and B, and the variation in the resistance value of the conductor 12 was within 10%.

  As described above, according to Examples 1, 2, 7, and 8, 650 in the oxidation reaction between the second metal constituting the first metal layer 14 and the fourth metal constituting the second metal layer 16 and oxygen. The standard free energy of formation at 0 ° C. is smaller than the standard free energy of formation at 650 ° C. in the oxidation reaction between the first metal constituting the power supply pad 13 and the third metal constituting the buffer member 15 and oxygen, and −150 Kcal When the ratio is larger than / mol, the connection state of the power supply terminal 17 is good under the conditions A and B, and the resistance value of the conductor 12 varies within 10%.

(Examples 3 to 6)
Example 3 was the same as Example 2 except that the first metal layer 14 and the second metal layer 16 were made of tantalum (Ta). Example 4 was the same as Example 2 except that the first metal layer 14 and the second metal layer 16 were made of silicon (Si). Example 5 was the same as Example 2 except that the first metal layer 14 and the second metal layer 16 were made of titanium (Ti). Example 6 was the same as Example 2 except that the first metal layer 14 and the second metal layer 16 were made of aluminum (Al).

  Thereby, in Examples 3-6, the standard production | generation in 650 degreeC in the oxidation reaction of the 2nd metal which comprises the 1st metal layer 14, and the 4th metal which comprises the 2nd metal layer 14, and oxygen The free energy is smaller than the standard free energy of formation at 650 ° C. in the oxidation reaction between the first metal constituting the power supply pad 13 and the third metal constituting the buffer member 15 and oxygen, and larger than −250 Kcal / mol. .

  In Examples 3 to 6, as in Example 1, under the condition A, the connection state of the power supply terminal 17 was good, and the variation in the resistance value of the conductor 12 was within 10%. Under the condition B, it was confirmed that the connection state of the power supply terminal 17 was defective, and the fluctuation of the resistance value of the conductor 12 exceeded 10%.

(Comparative Example 1)
Comparative Example 1 was the same as Example 1 except that the first metal layer 14 and the second metal layer 16 were not present.

  In Comparative Example 1, it was confirmed that the connection state of the power supply terminal 17 was defective under the conditions A and B, and the variation in the resistance value of the conductor 12 exceeded 10%.

(Comparative Example 2)
Comparative Example 2 was the same as Example 1 except that the first metal layer 14 and the second metal layer 16 were made of Ni.

  Thereby, in the comparative example 2, the standard free energy of formation at 650 ° C. in the oxidation reaction between the second metal constituting the first metal layer 14 and the fourth metal constituting the second metal layer 16 and oxygen. However, it is larger than the standard free energy of formation at 650 ° C. in the oxidation reaction between the first metal constituting the power supply pad 13 and the third metal constituting the buffer member 15 and oxygen.

  In Comparative Example 2, it was confirmed that the connection state of the power supply terminal 17 was poor in the conditions A and B, and the variation in the resistance value of the conductor 12 exceeded 10%.

  The above results are summarized in Tables 1 and 2.

  DESCRIPTION OF SYMBOLS 10 ... Ceramic substrate structure, 11 ... Ceramic base | substrate, 11a ... Upper surface (board | substrate mounting surface), 11b ... Lower surface, 11c ... Recessed part, 12 ... Conductor, 13 ... Feeding pad, 14 ... 1st metal layer (metal layer) 15 ... Buffer member (intermediate body), 16 ... Second metal layer, 17 ... Power feeding terminal, 18 ... Brazing material layer, 19 ... Cylindrical body, W ... Substrate.

Claims (5)

A substrate mounting surface on which a substrate is mounted, a concave portion is formed on a surface opposite to the substrate mounting surface, and a ceramic base made of ceramic;
A conductor built in the ceramic substrate;
A power supply pad made of a first metal electrically connected to the conductor, embedded in the ceramic base, and having a surface opposite to the conductor defining at least part of the bottom surface of the recess;
A power supply terminal for supplying power to the conductor via the power supply pad;
A metal layer made of a second metal, covering at least a part of the surface of the power supply pad opposite to the conductor and exposed to the outside,
The standard free energy of formation at 650 ° C. in the oxidation reaction of the second metal and oxygen is smaller than the standard free energy of formation at 650 ° C. in the oxidation reaction of the first metal and oxygen, and from −250 Kcal / mol. A ceramic substrate structure characterized by being large.   2. The ceramic substrate structure according to claim 1, wherein the standard free energy of formation at 650 ° C. in the oxidation reaction between the second metal and oxygen is greater than −150 Kcal / mol. The intermediate body is located between the power supply pad and the power supply terminal, is made of a third metal, and the surface exposed to the outside is covered with the fourth metal,
The standard free energy of formation at 650 ° C. in the oxidation reaction of the fourth metal and oxygen is smaller than the standard free energy of formation at 650 ° C. in the oxidation reaction of the first metal and oxygen, and from −250 Kcal / mol. The ceramic substrate structure according to claim 1 or 2, wherein the ceramic substrate structure is large. A substrate mounting surface on which a substrate is mounted, a conductor and a power supply pad made of a first metal that is electrically connected to the conductor, and a ceramic base made of ceramic is prepared;
Forming a recess in a surface opposite to the substrate mounting surface and exposing a part of the power supply pad;
Covering the exposed surface of the power supply pad with a metal layer made of a second metal;
Electrically connecting a power supply terminal to the power supply pad,
The standard free energy of formation at 650 ° C. in the oxidation reaction of the second metal and oxygen is smaller than the standard free energy of formation at 650 ° C. in the oxidation reaction of the first metal and oxygen, and −250 Kcal / mol. The manufacturing method of the ceramic substrate structure characterized by being larger. Preparing an intermediate body made of a third metal and having a surface covered with a fourth metal;
By fixing the intermediate body between the power supply pad and the power supply terminal, the power supply pad and the power supply terminal are electrically connected,
The standard free energy of formation at 650 ° C. in the oxidation reaction of the fourth metal and oxygen is smaller than the standard free energy of formation at 650 ° C. in the oxidation reaction of the first metal and oxygen, and from −250 Kcal / mol. The method for producing a ceramic substrate structure according to claim 4, wherein the ceramic substrate structure is large.