JP5368053B2 - Multilayer ceramic substrate and manufacturing method thereof - Google Patents

Description

  In the present invention, for example, a silicon wafer in which a connection terminal for electrical inspection of a silicon wafer can be mounted with high accuracy on the surface layer, and a circuit is formed even in an inspection in a wide temperature range (−50 to 150 ° C.). The present invention relates to a multilayer ceramic substrate capable of taking a similar behavior with respect to elongation and shrinkage of a wafer and a manufacturing method thereof.

  In recent years, there has been an increasing demand for IC inspection in units of Si wafers. In particular, at the present time when the size of Si wafers is increasing, it is necessary to handle wafers with a diameter of 300 mm (12 inches).

  Further, when inspecting these wafers, it is necessary to form connection terminals that contact the IC on the measurement jig, and the connection terminals need to be strong in order to contact repeatedly.

Furthermore, recently, there is a need for KGD (Known Good Die), which is guaranteed as an acceptable product in the wafer state when performing electrical inspection of the wafer.
As a process for obtaining this KGD, it is indispensable to perform a burn-in inspection (selection test with application of heat and electrical load) in a wafer state.

  However, the electrical inspection jig for wafers currently used (wafer inspection jigs) has a coefficient of thermal expansion that is very different from that of wafers. Due to the thermal expansion of the wafer, a dimensional deviation occurs between the wafer inspection jig and the wafer, and the connection terminal of the wafer inspection jig cannot contact the pad on the wafer.

Therefore, in the wafer and the wafer inspection jig (particularly, the substrate of the wafer inspection jig), it is important to adjust (adjust) the thermal expansion coefficient to some extent.
As techniques for combining the thermal expansion coefficients of the wafer and the substrate of the wafer inspection jig, techniques described in the following cited documents 1 to 5 are disclosed.
JP 55-139709 A JP-A-6-316463 JP-A-1-13599 JP-A-5-178658 Japanese Patent Laid-Open No. 4-243982

  However, in any cited document, it is not considered to accurately match the thermal expansion coefficients of the wafer and the substrate of the wafer inspection jig in a wide temperature range such as an inspection range.

  In addition, in particular, when a multilayer ceramic substrate for wafer inspection is manufactured, there is a problem that a large amount of liquid phase is generated during firing, so that the multilayer ceramic substrate is fused with the firing setter.

  The present invention has been made to solve the above-described problems. For example, even in the case of a test with a large temperature difference, the pad on the wafer and the connection terminal formed on the substrate can be connected without poor connection. An object of the present invention is to provide a multilayer ceramic substrate capable of preventing fusion with a fired setter during firing and a method for producing the same.

(1) The invention of claim 1, mullite _{(3Al 2 O 3 · 2SiO 2} ) a multilayer ceramic substrate having a ceramic whose main crystal, the multilayer ceramic substrate, electric inspection of a silicon wafer (Si wafer) The mullite content is 93 to 99% by mass of the ceramic component, and contains at least one of Mg and Y as a component other than the mullite. The ceramic substrate contains at least one of W and Mo as a component of the conductive layer, and further has an average coefficient of thermal expansion of −50 to 150 ° C. of 3.0 to 4.0 ppm / ° C., and −50 the thermal expansion coefficient [alpha] 1 of the temperature in to 150 DEG ° C., the thermal expansion coefficient [alpha] 2 of Si at the same temperature has a relationship of 0ppm / ℃ <α1-α2 ≦ 2.5ppm / ℃ It is characterized by that.

In the multilayer ceramic substrate used for the electrical inspection jig of the silicon wafer of the present invention, mullite, which is a low thermal expansion material, is used as a main crystal, and in addition to mullite, Mg and / or Y is contained (Mg and Y are Present as an oxide), the average thermal expansion coefficient of −50 to 150 ° C. is in the range of 3.0 to 4.0 ppm / ° C., and the same temperature as the thermal expansion coefficient α1 of each temperature at −50 to 150 ° C. and a thermal expansion coefficient [alpha] 2 of the Si wafer at is set the relationship of 0ppm / ℃ <α1-α2 ≦ 2.5ppm / ℃.

If the content of magnesia (MgO), which is an oxide of Mg, or yttria (Y ₂ O ₃ ), which is an oxide of Y, is high, the thermal expansion coefficient of the multilayer ceramic substrate increases. By doing so, the thermal expansion coefficient of the multilayer ceramic substrate can be adjusted.

Here, the reason why the range of the thermal expansion coefficient is set as described above will be described.
In an electrical inspection of a silicon wafer, an inspection is usually performed in a temperature range of −50 to 150 ° C., and an electrical inspection jig for a silicon wafer and a silicon wafer ( hereinafter simply referred to as a wafer inspection jig) in this temperature range. difference in the thermal expansion coefficient of the substrate also) be referred to as small is desirable.

In particular, in the burn-in inspection, only the silicon wafer is heated, and the wafer inspection jig is heated by the radiant heat. Therefore, the silicon wafer inevitably has a higher temperature than the wafer inspection jig. Therefore, when the wafer inspection tool to the same thermal expansion coefficient as silicon wafers, since the behavior of shrinkage or expansion of the wafer inspecting jig and the silicon wafer can not match, the substrate mounted on the wafer inspection jig Needs to have a thermal expansion coefficient larger than that of the silicon wafer within a predetermined upper limit.

Specifically, at the lowest temperature of −50 ° C., the range of the thermal expansion coefficient of this multilayer ceramic substrate is 0 ppm / ° C. <α1-α2 ≦ 1.5 ppm / ° C., which is the highest temperature of 150 ° C. in ° C., this range is 0.5ppm / ℃ ≦ α1-α2 ≦ 2.5ppm / ℃. In particular, when α1 is larger than α2 by 2.5 ppm / ° C at high temperatures (150 ° C), there is a temperature difference between the wafer and the inspection jig. Since the deviation occurs and deviates from the dimension that allows the connection terminal to be placed on the pad, the setting is made in this way. The same can be said for the low temperature (−50 ° C.).

  Here, the scope of the present invention is shown in a graph, for example, as shown in FIG. The range of the present invention is a range shown in gray, and the hatched range is a more preferable range. In addition, the range of oblique lines is the coordinates A (−50, 0), B (−50, 1.5), C (150) indicated by (temperature [° C.], difference in thermal expansion coefficient [α1−α2]). , 2.5) and D (150, 0.5). In the same figure, the equivalent product of the present invention is an example within the scope of the present invention, and the conventional product is an example outside the scope of the present invention. Furthermore, as shown in FIG. 2, the thermal expansion coefficient at each temperature is a value obtained by calculating the slope of the dimensional change rate due to temperature change at each temperature, that is, the tangential slope at each temperature (instantaneous thermal expansion coefficient). . The test piece in the figure is a multilayer ceramic substrate (vertical 20 mm × horizontal 4 mm × thickness 3 mm) or a part of a Si wafer rod (vertical 20 mm × horizontal 4.5 mm × thickness 4.5 mm).

Accordingly, the present invention, a multilayer ceramic substrate having the above structure, since the use as a substrate for an electric inspection jig of a silicon wafer having sufficient dimensional accuracy in terms of electrical connection between the silicon wafer pad In addition, even when the temperature is changed during inspection or the like, the wafer pad and the connection terminal formed on the substrate can be connected without poor electrical connection.
In other words, in the present invention, a connection terminal for electrical inspection of a silicon wafer can be mounted on the surface layer with high accuracy, and a silicon wafer on which a circuit is formed even in an inspection performed in a wide temperature range such as a burn-in test. It is possible to take a similar behavior with respect to the expansion and contraction of the dimension.

  In the present invention, when the content of mullite is less than 93% by mass, the amount of additive other than mullite (sintering aid and the like) Mg and Y increases, and as a result, it is generated during firing. The liquid phase component increases and causes fusion with the firing setter. In addition, when there is much liquid phase amount, depending on the composition contained, the chemical resistance to the chemical | medical solution (for example, hydrofluoric acid) used at the time of connection terminal formation falls. On the other hand, when the content of mullite exceeds 99% by mass, since the additive is insufficient, the liquid phase is not sufficiently generated, and the ceramic substrate is not sufficiently sintered. Therefore, the scope of the present invention is suitable.

  As a measuring method for distinguishing mullite from other components, a quantitative method by X-ray diffraction using an internal standard method can be adopted. In the quantitative method by the X-ray diffraction method using the internal standard method, the content of each crystal phase can be calculated from the ratio of the peak intensity of the diffraction X-ray of each crystal phase. That is, it can be said that the stronger the X-ray peak, the more the crystal phase is contained. As the internal standard substance, a substance having a crystallinity as high as possible (for example, Si) is used.

  Furthermore, when simultaneously firing a multilayer ceramic substrate having a conductor layer therein, it is necessary to match the firing temperatures of the metallized paste to be a W or Mo conductor layer and the ceramic component. W and Mo used in the present invention are high melting point metals, but by adding Mg or Y as a sintering aid to the ceramic component, the firing temperature of the W or Mo metallized paste and the ceramic component can be matched. And a dense and suitable fired body can be obtained.

(2) The invention of claim 2 is characterized in that the content of Mg contained in the ceramic is 1.0 to 5.0% by mass in terms of oxide.
When the content of Mg oxide (MgO) is less than 1.0% by mass, the densification temperature rises. On the other hand, if it exceeds 5.0% by mass, the amount of liquid phase produced becomes excessive, causing fusion with the calcined setter, and chemical resistance against chemicals such as hydrofluoric acid is reduced. Therefore, the scope of the present invention is suitable.

(3) The invention of claim 3 is characterized in that the content of Y contained in the ceramic is 2.0 to 7.0% by mass in terms of oxide.
When the content of Y oxide (Y ₂ O ₃ ) is less than 2.0% by mass, the densification temperature is increased. On the other hand, if it exceeds 7.0% by mass, the amount of liquid phase produced becomes excessive, causing fusion with the calcined setter, and chemical resistance against chemicals such as hydrofluoric acid is reduced. Therefore, the scope of the present invention is suitable.

(4) The invention of claim 4 has a characteristic that the weight reduction rate of the ceramic when the multilayer ceramic substrate is immersed in 3% hydrofluoric acid at 60 ° C. for 20 minutes is 10 g / m ² or less. It is characterized by.

The present invention shows a preferable range of chemical resistance of a multilayer ceramic substrate.
In other words, when using a technology such as MEMS (microelectromechanical system) when forming the connection terminals of the wafer inspection jig, the chemical resistance is regarded as important, but the chemical resistance within the scope of the present invention. If it has, even when a specific chemical (for example, hydrofluoric acid) is used in the process of forming the connection terminal, the multilayer ceramic substrate is prevented from being eroded, and the strength of the connection part such as the connection terminal The decrease can be suppressed.

(5) The invention of claim 5, wherein a claim 1 a method for producing a multilayer ceramic substrate according to any one of 4, as a ceramic material, mullite as a main component, at least Mg and Y A step of forming a green sheet using a material containing one kind, a step of forming a conductor using a material containing at least one kind of W and Mo on the green sheet, and a green sheet on which the conductor is formed A step of laminating a predetermined number of sheets to form a green sheet laminate, a step of degreasing and firing the green sheet laminate to form a fired body, and a step of polishing the surface of the fired body And a step of forming a surface conductor on the polished surface of the fired body.

By the manufacturing method of the present invention, the above-described multilayer ceramic substrate can be easily manufactured.
Multilayer ceramic substrate produced in this manner, since the need use as a substrate for an electric inspection jig of a silicon wafer, even when changing the temperature during the inspection, are formed on the silicon wafer pad and substrate The connection terminals can be connected without poor electrical connection.

  Here, 1400-1600 degreeC is mentioned as a calcination temperature at the time of the said baking. This is because if firing at a temperature lower than 1400 ° C., simultaneous firing of the substrate and the conductor becomes difficult, and firing at a temperature higher than 1600 ° C. promotes grain growth, resulting in a large void in the fired body. This is because the ceramic strength is reduced.

Embodiments of the present invention will be described below with reference to the drawings.
[Embodiment]
a) First, the multilayer ceramic substrate of the present embodiment will be described with reference to FIGS.

As shown in FIG. 3, the multilayer ceramic substrate 1 of the present embodiment has a ceramic layer 3 containing mullite as the main crystal and Mg and / or Y (and hence MgO and / or Y ₂ O ₃ ) in the balance in the thickness direction. It is a rectangular parallelepiped sintered body having a structure in which a plurality of layers are stacked, for example, a thickness of 5 mm × length of 300 mm × width of 300 mm.

  In the ceramic layer 3, the content of mullite is 93 to 99% by mass of the ceramic component, the content of Mg is 1.0 to 5.0% by mass of the ceramic component in terms of oxide, and the content of Y However, it is 2.0-7.0 mass% of a ceramic component in conversion to an oxide.

In addition, the ceramic layer 3 has an average thermal expansion coefficient of −50 to 150 ° C. of 3.0 to 4.0 ppm / ° C., and a thermal expansion coefficient α1 of each temperature at −50 to 150 ° C. at the same temperature. the thermal expansion coefficient of the Si wafer [alpha] 2 has a property which is 0ppm / ℃ <α1-α2 ≦ 2.5ppm / ℃.

  In addition, a conductive electrode 5 is formed on the surface of the multilayer ceramic substrate 1, and an internal wiring layer 7 is formed inside the multilayer ceramic substrate 1 (specifically, a boundary portion between the ceramic layers 3). Furthermore, an interlayer connection conductor (via) 9 extending in the thickness direction of the substrate is formed so as to electrically connect the electrode 5 on the front surface and the electrode 5 on the back surface of the multilayer ceramic substrate 1 via the internal wiring layer 7. ing.

Therefore, as shown in FIG. 4, many electrodes 5 are exposed on the surface of the multilayer ceramic substrate 1.
In addition, as a conductor (surface conductor) which comprises the electrode 5, Ti, Cr, Mo, Cu, Ni, Au, and the thing which combined them can be employ | adopted, and the conductor (internal part which comprises the internal wiring layer 7 and the via | veer 9) As the conductor), a conductor made of W and / or Mo that can be fired simultaneously when the ceramic is fired can be used.

Further, as shown in FIG. 5, a conductive probe 11 is connected to the electrode 5 of the multilayer ceramic substrate 1 having the above-described configuration (used as an electric inspection jig for a silicon wafer). IC inspection substrate 13 Is configured.
This IC inspection substrate 13 corresponds to, for example, a φ300 mm (12 inch) Si wafer 15, and once the probe 11 comes into contact with the IC terminal 17 in the Si wafer 15 (before each IC is cut out), In addition, it is possible to inspect a large number of ICs.

  b) Next, the manufacturing method of the multilayer ceramic substrate 1 of this embodiment is demonstrated in detail based on FIG.6 and FIG.7. 6 and 7, since the substrate shape is simplified, the arrangement of vias 9 is slightly different from FIG.

(1) First, a mullite (3Al ₂ O ₃ .2SiO ₂ ) powder having an average particle size of 2 μm and a specific surface area of 3.0 m ² / g is prepared as a ceramic raw material powder, and an average particle size of 7 μm and a specific ratio are added as additives. and MgCO ₃ powder surface area 30 m ² / g, an average particle diameter of 1 [mu] m, were prepared Y ₂ O ₃ powder having a specific surface area of 12m ² / g.

Further, a butyral resin and DOP (di-octyl phthalate) were prepared as a binder component and a plasticizer component during sheet molding.
Then, in an alumina pot, mullite powder and MgCO ₃ powder are mixed with 99 parts by weight of mullite powder, 2.5 parts by weight of MgCO ₃ powder (1 part by weight in terms of oxide), and mullite powder 97 3 parts by weight of Y ₂ O ₃ powder was added with respect to parts by weight so that the total amount became 1 kg, and 120 g of butyral resin was added.

  Further, a ceramic slurry was obtained by putting an amount of a solvent (MEK: methyl ethyl ketone) and a plasticizer (DOP) necessary for giving an appropriate slurry viscosity and sheet strength into the pot and mixing them for 5 hours.

Using the obtained ceramic slurry, a green sheet 21 (for each ceramic layer 3) having a thickness of 0.15 mm was produced by a doctor blade method as shown in FIG. 6 (a).
(2) Next, as shown in FIG. 6B, via holes 25 having a diameter of 0.12 mm were formed in the green sheet 21 by punching.

(3) Next, as shown in FIG. 6C, the via hole 25 is filled with, for example, a W-based paste to form a filling portion 27 (which becomes the via 9).
(4) Further, as shown in FIG. 6D, a conductive pattern 29 (to be the internal wiring layer 7) was formed by printing using a W-based paste at a required position on the surface of the green sheet 21.

(5) Next, as shown in FIG. 6E, the green sheets 21 manufactured as described above were sequentially laminated to form a green sheet laminate 31.
(6) Next, as shown in FIG. 7A, the green sheet laminate 31 is fired (degreasing fired) for 2 hours at 1550 ° C. in an N ₂ atmosphere containing 50% by volume of H ₂ and sintered. A body 33 was obtained.

(7) Next, as shown in FIG. 7B, both outer surfaces of the sintered body 33 were polished by lapping using alumina abrasive grains.
(8) Next, as shown in FIG. 7C, after a Ti thin film, for example, is formed as a surface conductor at the position corresponding to the via 9 on the surface of the polished sintered body 33 by a sputtering method, Cu, Ni The electrode 5 was formed by Au plating, and the multilayer ceramic substrate 1 was completed.

  c) Thus, in the multilayer ceramic substrate 1 of the present embodiment, the mullite is 93 to 99% by mass, the oxide converted Mg is 1.0 to 5.0% by mass, and the oxide converted Y is 2.0 to 2.0%. 7.0% by mass.

Therefore, as is clear from experimental examples described later, this multilayer ceramic substrate 1 has an average coefficient of thermal expansion of −50 to 150 ° C. of 3.0 to 4.0 ppm / ° C., and each of the multilayer ceramic substrates 1 at −50 to 150 ° C. the thermal expansion coefficient [alpha] 1 of the temperature, and the thermal expansion coefficient [alpha] 2 of the Si wafer at the same temperature is 0 ppm / ℃ <α1-α2 ≦ 2.5ppm / ℃. Moreover, it has a high relative density, a high chemical resistance, and a remarkable effect of not being fused to the setter during firing.

Therefore, this multilayer ceramic substrate 1 is suitable for use as a substrate for an electric inspection jig for a silicon wafer. Specifically, a sufficient dimensional accuracy in terms of electrical connection between the pads 17 of the Si wafer 15, yet, even when changing the temperature during the inspection, the pad 17 of the Si wafer 15 and the substrate The probe 11 formed on 1 can be connected without poor electrical connection.

  In this experimental example, using the materials shown in Table 1 below, the relative density of the sintered body, the average thermal expansion coefficient, (α1-α2) at −50 ° C., 30 ° C., and 150 ° C. under the following conditions: The weight reduction after acid immersion and the presence or absence of fusion with the firing setter were examined. The results are shown in Table 2 below.

a) Coefficient of thermal expansion Mullite powder, MgCO ₃ powder, and Y ₂ O ₃ powder similar to those in the above embodiment were used in the proportions shown in Table 1 below to prepare samples used in the experiment.

Specifically, mullite powder, MgCO ₃ powder, and Y ₂ O ₃ powder are mixed in an alumina pot at a predetermined ratio (a ratio of the composition shown in Table 1 below after firing) so that the total amount becomes 100 g. Were weighed and charged. These were mixed with 150 g of ethanol and then discharged out of the pot, and the ethanol content was dried and removed.

In the comparative example, use an average particle diameter of 2.0 .mu.m, and Al ₂ O ₃ powder having a specific surface area of 2.1 m ² / g, an average particle diameter of 2.1 .mu.m, a SiO ₂ powder having a specific surface area of 12.6 m ² / g It was.
Thereafter, 4 g of an acrylic binder and 100 g of acetone were added to the obtained mullite powder and additives, the acetone was evaporated in a mortar, mixed well, and dried to obtain a sample powder.

  Next, this sample powder was put in a mold to form a 3 mm × 3 mm × 20 mm rod-shaped test piece, and a pressure of 5 Mpa was applied to the test piece to obtain a molded body. The molded body was fired at 1550 ° C. for 2 hours in the air to prepare a sample for evaluating the thermal expansion coefficient.

  And the dimensional variation rate to -60-200 degreeC was measured with the thermomechanical analyzer (TMA) with respect to each said sample, and the elongation and measurement temperature in measurement were sampled and investigated. Specifically, sampling is performed every 1.0 seconds, the measured values are graphed (vertical axis (elongation), horizontal axis (temperature)), and the coefficient of thermal expansion (α1) is calculated from the slope before and after sampling. Asked. Moreover, the average thermal expansion coefficient was calculated | required from the inclination of the graph in -50-150 degreeC. The results are shown in Table 2 below.

b) Difference in thermal expansion coefficient at −50 ° C., 30 ° C., and 150 ° C. (α1−α2)
Using a part of the rod of the Si wafer, the thermal expansion coefficient (α2) at the time of −50 ° C., 30 ° C., and 150 ° C. was determined in the same manner as the measurement of the thermal expansion coefficient (α1) of a). And α1-α2 was calculated. The results are shown in Table 2 below.

A sample having a length of 20 mm, a width of 4.5 mm, and a thickness of 4.5 mm was used as a part of the rod of the Si wafer.
c) Relative density (sinterability after firing)
Using a sample prepared in the same manner as in a) above, the specific gravity after firing of this sample was measured by the Archimedes method, and the relative specific gravity was calculated from the theoretical specific gravity. The results are shown in Table 2 below.

d) Weight reduction after acid immersion The same sample powder as in a) above was placed in a cylindrical mold having a diameter of 19 mm, and a pressure of 5 Mpa was applied to obtain a press-molded body. The molded body was fired at 1550 ° C. for 2 hours in the air to obtain a sample of the fired body.

This sample was immersed in 3% hydrogen fluoride at 60 ° C. for 20 minutes, and the weight loss before and after the immersion was measured. The weight reduction amount (g / m ² ) per unit area was determined by dividing the weight reduction amount (g) by the surface area (m ² ) of the sample. The results are shown in Table 2 below.

e) Fusion with Firing Setter When producing a sample in the same manner as in a), the presence or absence of fusion with the calcining setter on which the sample was placed was examined. The results are shown in Table 2 below. In addition, (circle) shows no fusion | fusion and x shows fusion presence.

In Table 2, a sample that did not satisfy any of the claims 1 to 3 was used as a comparative example.

Ming Kana Luo from Table 2, in Examples 1-8 of the scope of the present invention, mullite is 93-99 wt%, and, Mg in terms oxide 1.0 to 5.0 wt%, Since Y in terms of oxide is 2.0 to 7.0% by mass, the produced ceramic substrate or the like has an average thermal expansion coefficient of 3.0 to 4.0 ppm / ° C. , and the ceramic substrate and silicon at each temperature. difference of thermal expansion coefficient is 0 ppm / ℃ <α1-α2 ≦ 2.5ppm / ℃. In addition, the relative density is as high as 92% or more, the weight reduction rate before and after immersion by immersion in hydrofluoric acid is suppressed to 4.0 g / m ² or less, and no fusion to the setter during firing is observed. It was.

  On the other hand, in Comparative Example 1, since the mullite content is excessive and there is no sintering aid, the ceramic is not sufficiently densified, which is not preferable. In Comparative Examples 2 and 3, since the mullite content is too small and the addition amount of Mg or Y is too large, the chemical resistance is low and the setter is fused, which is not preferable. Comparative Examples 4 and 5 are not preferable because the mullite content is too low and the setter has fusion. In Comparative Examples 6 and 7, since Mg or Y is not included, the ceramic is not sufficiently densified, which is not preferable.

  In addition, this invention is not limited to the said embodiment at all, and it cannot be overemphasized that it can implement with a various aspect in the range which does not deviate from this invention.

It is explanatory drawing which shows the range of the thermal expansion coefficient of this invention. It is explanatory drawing for demonstrating the definition of the thermal expansion coefficient in each temperature of this invention. It is sectional drawing which shows the cross section of the multilayer ceramic substrate of embodiment. It is a top view which shows a part of substrate surface of the multilayer ceramic substrate of embodiment. It is explanatory drawing which shows the usage method of the board | substrate for IC inspection . It is explanatory drawing which shows the manufacturing method of the multilayer ceramic substrate of embodiment . It is explanatory drawing which shows the manufacturing method of the multilayer ceramic substrate of embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Multilayer ceramic substrate 3 ... Ceramic layer 5 ... Electrode 7 ... Internal conductive layer 9 ... Via 13 ... IC inspection substrate 21 ... Green sheet 31 ... Green sheet laminated body 33 ... Firing body

Claims (5)

A multilayer ceramic substrate having a ceramic mainly composed of mullite,
The multilayer ceramic substrate is used for a jig for electrical inspection of a silicon wafer,
The mullite content is 93 to 99% by mass of the ceramic component.
And as a component other than the mullite, it contains at least one of Mg and Y,
The multilayer ceramic substrate contains at least one of W and Mo as a component of the conductive layer,
Furthermore, the average thermal expansion coefficient of −50 to 150 ° C. is 3.0 to 4.0 ppm / ° C., and the thermal expansion coefficient α1 of each temperature at −50 to 150 ° C., and the thermal expansion coefficient of Si at the same temperature multilayer ceramic substrate [alpha] 2 and is characterized by having a relationship of 0ppm / ℃ <α1-α2 ≦ 2.5ppm / ℃.   The multilayer ceramic substrate according to claim 1, wherein the content of Mg contained in the ceramic is 1.0 to 5.0 mass% in terms of oxide.   3. The multilayer ceramic substrate according to claim 1, wherein the content of Y contained in the ceramic is 2.0 to 7.0% by mass in terms of oxide. The weight reduction rate of the ceramic when the multilayer ceramic substrate is immersed in 3% hydrofluoric acid at 60 ° C for 20 minutes has a characteristic of 10 g / m ² or less. the multilayer ceramic substrate according to any one. A method of manufacturing a multilayer ceramic substrate according to any one of the preceding claims 1-4,
Forming a green sheet using a material containing mullite as a main component and containing at least one of Mg and Y as a ceramic material;
Forming a conductor on the green sheet using a material containing at least one of W and Mo;
A step of laminating a predetermined number of green sheets on which the conductor is formed to form a green sheet laminate;
A step of degreasing and firing the green sheet laminate to form a fired body;
Polishing the surface of the fired body;
Forming a surface conductor on the polished surface of the fired body;
A method for producing a multilayer ceramic substrate, comprising: