JP2004168658A - Ceramic substrate for semiconductor manufacture/inspection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic substrate for a semiconductor manufacture/inspection apparatus which is free from the falling-off of particles by polishing and has a flatly formed surface because the ceramic substrate has excellent sintering properties and high density, small inner pore diameter and the firm joint of the particles to each other constituting a sintered compact. <P>SOLUTION: In the ceramic substrate having a conductor formed in the inside or on the surface of a ceramic substrate, the glossiness of the surface of the ceramic substrate is ≥2%. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a ceramic substrate mainly used in the semiconductor industry, and in particular, has a high withstand voltage, and when used for an electrostatic chuck, has an excellent ability to attract a semiconductor wafer and is used as a hot plate (heater). In some cases, the present invention relates to a ceramic substrate for a semiconductor manufacturing / inspection apparatus having excellent temperature rise / fall characteristics.

2. Description of the Related Art Semiconductors are extremely important products required in various industries. For example, semiconductor chips are prepared by slicing a silicon single crystal to a predetermined thickness to produce a silicon wafer, and then forming a plurality of integrated circuits on the silicon wafer. And the like.

In this semiconductor chip manufacturing process, various processes such as etching and CVD are performed on a silicon wafer mounted on an electrostatic chuck to form a conductor circuit, an element, and the like. At this time, since corrosive gases are used as a deposition gas, an etching gas, and the like, it is necessary to protect the electrostatic electrode layer from corrosion by these gases, and it is necessary to induce an adsorption force. Therefore, the electrostatic electrode layer is usually covered with a ceramic dielectric film or the like.

Conventionally, a nitride ceramic has been used as the ceramic dielectric film. For example, Japanese Patent Application Laid-Open No. 5-8140 discloses an electrostatic chuck using a nitride such as aluminum nitride. Japanese Patent Application Laid-Open No. 9-48668 discloses a carbon-containing aluminum nitride having an Al-ON structure.

However, in the electrostatic chuck using these ceramics, particles fall off and adhere to a wafer or the like to form particles, which causes a defect when a circuit is formed on a semiconductor wafer.

Further, a sintering aid is added to the ceramic, but the sintering aid is usually present at the grain boundary and becomes a defect, resulting in a decrease in strength such as bending strength at a high temperature. It has been found that such a problem is found not only in the electrostatic chuck but also in various ceramic substrates for manufacturing and inspecting semiconductors in which a conductor is formed on the surface or inside of the ceramic substrate.

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, when firing a molded body containing ceramic particles into a sintered body, the sintered body is sintered so that the fracture cross section is intra-particle fracture. I learned that it was good. Specifically, the surface of the nitride ceramic particles is first oxidized, and then the oxide is added and sintering is performed, so that the sintering is performed so that the fracture cross section becomes intra-particle fracture. The inventors have found that the present invention can be performed, and have completed the present invention.

That is, the present invention relates to a ceramic substrate for a semiconductor manufacturing / inspection apparatus having a conductor formed on the surface or inside thereof, wherein the ceramic substrate is sintered so that its fracture cross section becomes intra-particle fracture. A ceramic substrate for a semiconductor manufacturing / inspection apparatus, characterized in that:

The semiconductor manufacturing / inspection apparatus according to the present invention refers to an apparatus used for semiconductor manufacturing and inspection such as a ceramic heater (hot plate), a wafer prober, and an electrostatic chuck. Hereinafter, the ceramic substrate for a semiconductor manufacturing / inspection apparatus is simply referred to as a ceramic substrate.

In addition, the intragranular fracture referred to in the present invention refers to a case where a fracture occurs not inside a boundary between ceramic particles but inside a ceramic particle when a fracture cross section is observed, and is synonymous with intragranular fracture. Since the ceramic substrate is sintered so that its fracture cross section is broken within particles, particles are less likely to fall off and particles are less likely to be generated. Further, there is almost no barrier between the particles, and the strength at high temperatures is high.

Further, since the ceramic substrate whose fracture cross section is broken within particles has high rigidity, there is no warpage, and the amount of warpage due to its own weight is small even at a high temperature. In particular, a large, thin ceramic substrate having a diameter of 200 mm or more and a thickness of 25 mm or less tends to warp due to its own weight at high temperatures. For this reason, the distance between the ceramic substrate and the semiconductor wafer becomes non-uniform, so that there is a problem that the semiconductor wafer cannot be heated uniformly, or the semiconductor wafer is damaged when a force is applied. In the present invention, since the amount of warpage is small not only at room temperature but also at high temperature, the semiconductor wafer is excellent in uniform heating characteristics, and the semiconductor wafer is not damaged when used in a wafer prober.

The ceramic substrate of the present invention preferably has a warpage of 100 μm or less. If the warpage exceeds 100 μm, the distance between the semiconductor wafer to be heated and the ceramic substrate greatly varies, so that the semiconductor wafer cannot be heated uniformly and when used in a wafer prober. This is because the semiconductor wafer may be damaged.

The ceramic substrate of the present invention is desirably used at 100 to 800 ° C. This is because high-temperature strength is improved and warpage can be prevented. Particularly, it is optimal to use at 200 ° C. or higher.

Since the ceramic substrate of the present invention is sintered so that its fracture cross section is broken inside the particles, it has excellent strength characteristics at high temperatures, has a small number of particles, and is optimal as a ceramic substrate for semiconductor manufacturing / inspection equipment. It is.

In the present invention, for example, the surface of the particles of the nitride ceramic raw material is first oxidized, and then the oxide is added, followed by molding and firing, whereby the oxide layer of the nitride ceramic and the added oxide are added. A sintered body in which the objects are integrated is formed, and when such a sintered body is broken, the fracture cross section becomes intra-particle fracture.

In this case, the oxide to be added is preferably an oxide of an element constituting the nitride ceramic. This is because it is the same as the surface oxide layer of the nitride ceramic and is extremely easy to be sintered. In order to oxidize the surface of the nitride ceramic, it is desirable to heat at 500 to 1000 ° C. for 10 minutes to 3 hours in oxygen or air.

The average particle size of the nitride ceramic powder used for sintering is preferably about 0.1 to 5 μm. This is because sintering is easy. Further, it is desirable that the content of Si is 0.05 to 50 ppm and the content of S is 0.05 to 80 ppm (all by weight). This is because these are considered to combine the added oxide with the oxide film on the nitride ceramic surface. Other firing conditions will be described later in detail in a method of manufacturing an electrostatic chuck.

The ceramic substrate obtained by firing using the above method preferably contains 0.05 to 10% by weight of oxygen. If the content is less than 0.05% by weight, sintering does not proceed and fracture occurs at the grain boundaries, and defects occur, so that the flexural strength at high temperatures decreases. This is because oxygen and the like segregated in the steel become defects, and the bending strength at high temperatures is also lowered. In the present invention, whether or not the fractured cross section is fractured within the particle is confirmed by an electron microscope photograph at a magnification of 2000 to 5000 times.

In the present invention, the ceramic substrate is made of a nitride ceramic containing oxygen, and the maximum pore size is preferably 50 μm or less, and the porosity is preferably 5% or less. The ceramic substrate has no pores or, if pores exist, the maximum pore diameter is desirably 50 μm or less.

When no pores are present, the withstand voltage at high temperatures is particularly high, and when pores are present, the fracture toughness value is high. Or either the design for this is the vary required characteristics. The reason why the fracture toughness value is increased by the presence of the pores is not clear, but it is estimated that the cracks are stopped by the pores.

In the present invention, the pore diameter of the maximum pore is desirably 50 μm or less, because if the pore diameter exceeds 50 μm, it becomes difficult to secure a withstand voltage characteristic at a high temperature, particularly at 200 ° C. or more. The pore diameter of the largest pore is desirably 10 μm or less. This is because the amount of warpage at 200 ° C. or more is reduced.

The porosity and the maximum pore diameter are adjusted by the pressurization time, pressure, temperature, and additives such as SiC and BN during sintering. Since SiC and BN inhibit sintering, pores can be introduced.

When measuring the pore diameter of the largest pore, five samples are prepared, the surface thereof is mirror-polished, and the surface is photographed at 10 times with an electron microscope at a magnification of 2000 to 5000 times. Then, the maximum pore diameter is selected from the photographed images, and the average of 50 shots is defined as the maximum pore diameter.

The porosity is measured by the Archimedes method. Pulverize the sintered body, put the pulverized material in an organic solvent or mercury, measure the volume, calculate the true specific gravity from the weight and volume of the pulverized material, calculate the porosity from the true specific gravity and the apparent specific gravity .

The diameter of the ceramic substrate of the present invention is desirably 200 mm or more. In particular, it is desirable to be 12 inches (300 mm) or more. This is because it will become the mainstream of next-generation semiconductor wafers.

The thickness of the ceramic substrate of the present invention is desirably 50 mm or less, and particularly desirably 25 mm or less. When the thickness of the ceramic substrate exceeds 25 mm, the heat capacity of the ceramic substrate may be too large. In particular, when heating and cooling are performed by providing a temperature control unit, the temperature followability is reduced due to the large heat capacity. This is because there is a case where it is lost. The thickness of the ceramic substrate is most preferably 5 mm or less. The thickness of the ceramic substrate is desirably 1 mm or more.

The ceramic material constituting the ceramic substrate of the present invention is not particularly limited, but is preferably a nitride ceramic or a carbide ceramic. Examples of the nitride ceramic include metal nitride ceramics such as aluminum nitride, silicon nitride, boron nitride, and titanium nitride. Examples of the carbide ceramic include silicon carbide, titanium carbide, zirconium carbide, tantalum carbide, and tungsten carbide. Further, in the case of oxide ceramics, alumina, silica, beryllia and the like are used.

Among these nitride ceramics, aluminum nitride is particularly preferred. This is because the thermal conductivity is the highest at 180 W / m · K.

In the present invention, it is desirable that the ceramic substrate contains an oxide. Examples of the oxide include alumina (Al ₂ O ₃ ), rubidium oxide (Rb ₂ O), lithium oxide (Li ₂ O), calcium oxide (CaO), and silica (SiO ₂ ). The content of these is preferably 0.1 to 20% by weight. Particularly, in the case of aluminum nitride, alumina is preferable as the oxide, and in the case of silicon nitride, silica is most suitable as the oxide. However, oxides of rare earth elements are not preferred. For example, addition of Y ₂ O ₃ , Er ₂ O _3, etc. is not preferable because it is likely to cause grain boundary destruction.

In the present invention, it is desirable that the ceramic substrate contains 5 to 5000 ppm of carbon. By containing carbon, the ceramic substrate can be blackened, and radiant heat can be sufficiently utilized when used as a heater. The carbon may be amorphous or crystalline. When amorphous carbon is used, a decrease in volume resistivity at a high temperature can be prevented, and when a crystalline material is used, a decrease in thermal conductivity at a high temperature can be prevented. Because. Therefore, depending on the application, both crystalline carbon and amorphous carbon may be used in combination. Further, the content of carbon is more preferably 50 to 2000 ppm.

When carbon is contained in the ceramic substrate, it is desirable that carbon be contained so that its brightness is N6 or less as a value based on the provisions of JIS Z 8721. This is because a material having such a lightness is excellent in radiant heat and concealing property.

Here, N of lightness is 0 for ideal black lightness and 10 for ideal white lightness, and between these black lightness and white lightness, the perception of the lightness of the color is Each color is divided into 10 so as to have a uniform rate, and displayed by symbols N0 to N10. The actual measurement of lightness is performed by comparing with color patches corresponding to N0 to N10. In this case, the first decimal place is 0 or 5.

The ceramic substrate of the present invention is a ceramic substrate used for an apparatus for manufacturing a semiconductor or inspecting a semiconductor. Specific examples of the apparatus include an electrostatic chuck, a hot plate (ceramic heater), and a wafer prober. Is mentioned.

When the conductor formed inside the ceramic substrate is a resistance heating element, it can be used as a ceramic heater (hot plate).
FIG. 1 is a plan view schematically showing an example of a ceramic heater which is an embodiment of the ceramic substrate of the present invention, and FIG. 2 is a partially enlarged sectional view showing a part of the ceramic heater shown in FIG. is there.

The ceramic substrate 11 is formed in a disk shape, and a resistance heating element 12 as a temperature control means is formed in a concentric pattern inside the ceramic substrate 11. Further, these resistance heating elements 12 are connected such that double concentric circles close to each other form a single line as a set of circuits, and external terminals 13 serving as input / output terminals are provided at both ends of the circuit. They are connected via through holes 19.

As shown in FIG. 2, a through hole 15 is provided in the ceramic substrate 11, a support pin 26 is inserted through the through hole 15, and the silicon wafer 9 is held. By raising and lowering the support pins 26, the silicon wafer 9 is received from the transporter, the silicon wafer 9 is placed on the wafer processing surface 11a of the ceramic substrate 11 and heated, and the silicon wafer 9 is moved to the wafer processing surface 11a. It can be supported and heated in a state where it is separated from it by a certain interval. The bottom surface 11a of the ceramic substrate 11 is provided with a bottomed hole 14 for inserting a temperature measuring element such as a thermocouple. Then, when the resistance heating element 12 is energized, the ceramic substrate 11 is heated, so that an object to be heated such as a silicon wafer can be heated.

The resistance heating element may be provided inside the ceramic substrate, or may be provided on the bottom surface of the ceramic substrate. When a resistance heating element is provided, a blowing port for a refrigerant such as air may be provided as a cooling means in a support container into which the ceramic substrate is fitted. When the resistance heating element is provided inside the ceramic substrate, a plurality of layers may be provided. In this case, it is desirable that the patterns of the respective layers are formed so as to complement each other, and that the pattern is formed in any layer when viewed from the heating surface. For example, a staggered arrangement is used. In the present invention, it is desirable that the heating element is arranged at a position within 60% from the opposite side of the heating surface. This is to ensure the distance from the heating element to the heating surface and to ensure uniformity of the temperature distribution on the heating surface.

Examples of the resistance heating element include a sintered body of metal or conductive ceramic, a metal foil, a metal wire, and the like. As the metal sintered body, at least one selected from tungsten and molybdenum is preferable. This is because these metals are relatively hard to oxidize and have a resistance value sufficient to generate heat.

As the conductive ceramic, at least one selected from carbides of tungsten and molybdenum can be used. Further, when a resistance heating element is formed on the bottom surface of the ceramic substrate, it is desirable to use a noble metal (gold, silver, palladium, platinum) or nickel as the metal sintered body. Specifically, silver, silver-palladium, or the like can be used. The metal particles used in the metal sintered body may be spherical, flaky, or a mixture of spherical and flaky.

When forming the resistance heating element on the surface of the ceramic substrate, a metal oxide may be added to the metal and sintered. The use of the metal oxide is for bringing the ceramic substrate and the metal particles into close contact. The reason why the metal oxide improves the adhesion between the ceramic substrate and the metal particles is not clear, but the surface of the metal particles is slightly formed with an oxide film. Of course, even in the case of a non-oxide ceramic, an oxide film is formed on the surface. Therefore, it is considered that this oxide film is sintered and integrated on the surface of the ceramic substrate via the metal oxide, and the metal particles and the ceramic substrate adhere to each other.

As the metal oxide, for example, at least one selected from the group consisting of lead oxide, zinc oxide, silica, boron oxide (B ₂ O ₃ ), alumina, yttria, and titania is preferable. This is because these oxides can improve the adhesion between the metal particles and the ceramic substrate without increasing the resistance value of the resistance heating element.

It is desirable that the metal oxide is present in an amount of from 0.1 part by weight to less than 10 parts by weight based on 100 parts by weight of the metal particles. By using a metal oxide in this range, the resistance value does not become too large, and the adhesion between the metal particles and the ceramic substrate can be improved.

The ratio of lead oxide, zinc oxide, silica, boron oxide (B ₂ O ₃ ), alumina, yttria, and titania is such that when the total amount of the metal oxide is 100 parts by weight, the lead oxide is 1 to 10 parts by weight. 1 to 30 parts by weight of silica, 5 to 50 parts by weight of boron oxide, 20 to 70 parts by weight of zinc oxide, 1 to 10 parts by weight of alumina, 1 to 50 parts by weight of yttria, 1 to 50 parts by weight of titania Is preferred. However, it is desirable that the total be adjusted within a range not exceeding 100 parts by weight. This is because these ranges are particularly ranges in which the adhesion to the ceramic substrate can be improved.

When the resistance heating element is provided on the bottom surface of the ceramic substrate, it is desirable that the surface of the resistance heating element 25 be covered with a metal layer 25a (see FIG. 5). The resistance heating element 25 is a sintered body of metal particles, and is easily oxidized when exposed, and the oxidation changes the resistance value. Therefore, oxidation can be prevented by coating the surface with the metal layer 25a.

The thickness of the metal layer 25a is desirably 0.1 to 100 μm. This is because the oxidation of the resistance heating element can be prevented without changing the resistance value of the resistance heating element. The metal used for coating may be a non-oxidizing metal. Specifically, at least one selected from gold, silver, palladium, platinum, and nickel is preferable. Of these, nickel is more preferred. The resistance heating element requires a terminal for connection to a power supply, and this terminal is attached to the resistance heating element via solder. Nickel prevents thermal diffusion of the solder. As the connection terminal, an external terminal made of Kovar can be used.

When the resistance heating element is formed inside the ceramic substrate, no coating is required because the surface of the resistance heating element is not oxidized. When the resistance heating element is formed inside the heater plate, a part of the surface of the resistance heating element may be exposed.

A metal foil or a metal wire can be used as the resistance heating element. As the metal foil, it is desirable to use a nickel foil or a stainless steel foil as a resistance heating element by forming a pattern by etching or the like. The patterned metal foil may be bonded with a resin film or the like. Examples of the metal wire include a tungsten wire and a molybdenum wire.

When the conductor formed inside the ceramic substrate is an electrostatic electrode layer, the ceramic substrate can be used as an electrostatic chuck. In this case, the RF electrode and the heating element may be formed below the electrostatic electrode and as a conductor in the ceramic substrate.
FIG. 3 is a longitudinal sectional view schematically showing one embodiment of the electrostatic chuck according to the present invention, and FIG. 4 is a sectional view taken along line AA of the electrostatic chuck shown in FIG.

In the electrostatic chuck 101, an electrostatic electrode layer including a chuck positive electrostatic layer 2 and a chuck negative electrostatic layer 3 is embedded in a disk-shaped ceramic substrate 1. A thin ceramic layer 4 (hereinafter referred to as a ceramic dielectric film) is formed thereon. A silicon wafer 9 is placed on the electrostatic chuck 101 and is grounded.

As shown in FIG. 4, the chuck positive electrode electrostatic layer 2 includes a semicircular arc portion 2a and a comb tooth portion 2b, and the chuck negative electrode electrostatic layer 3 also includes a semicircular arc portion 3a and a comb tooth portion 3b. The chucking positive electrode electrostatic layer 2 and the chucking negative electrode electrostatic layer 3 are arranged to face each other so as to intersect the comb teeth portions 2b and 3b. the electrostatic layer 3, and the + side of each DC power source - is the side connected, the DC voltage V ₂ is adapted to be applied.

Further, inside the ceramic substrate 1, a resistance heating element 5 having a concentric circular shape in plan view as shown in FIG. 1 is provided in order to control the temperature of the silicon wafer 9. the external terminal is connected, is fixed, so that the voltages V ₁ is applied. Although not shown in FIGS. 3 and 4, this ceramic substrate 1 has a bottomed hole for inserting a temperature measuring element and a support for supporting and raising and lowering the silicon wafer 9 as shown in FIGS. A through hole for inserting a pin (not shown) is formed. Note that the resistance heating element may be formed on the bottom surface of the ceramic substrate.

When the electrostatic chuck 101 is operated, a DC voltage V ₂ is applied to the chuck positive electrostatic layer 2 and the chuck negative electrostatic layer 3. As a result, the silicon wafer 9 is adsorbed and fixed to these electrodes via the ceramic dielectric film 4 by the electrostatic action of the chuck positive electrode electrostatic layer 2 and the chuck negative electrode electrostatic layer 3. . After fixing the silicon wafer 9 on the electrostatic chuck 101 in this manner, various processes such as CVD are performed on the silicon wafer 9.

In the electrostatic chuck 101, the ceramic dielectric film 4 is preferably made of a nitride ceramic containing oxygen, and has a porosity of 5% or less and a maximum pore diameter of 50 μm or less. It is desirable that the pores in the ceramic dielectric film 4 be constituted by pores independent of each other. In the ceramic dielectric film 4 having such a configuration, a gas or the like that lowers the withstand voltage may permeate the ceramic dielectric film and corrode the electrostatic electrode, or the withstand voltage of the ceramic dielectric film may decrease even at a high temperature. Absent.

As the temperature control means, in addition to the resistance heating element 12, a Peltier element (see FIG. 7) can be used. When a Peltier element is used as the temperature control means, it is advantageous that both heat generation and cooling can be performed by changing the direction of current flow. As shown in FIG. 7, the Peltier element 8 is formed by connecting p-type and n-type thermoelectric elements 81 in series and joining them to a ceramic plate 82 or the like. Examples of the Peltier element include silicon-germanium-based, bismuth-antimony-based, and lead / tellurium-based materials.

The electrostatic chuck of the present invention has, for example, a configuration as shown in FIGS. Although the material of the ceramic substrate and the like have already been described, in the following, other members constituting the above-mentioned electrostatic chuck, and other embodiments of the electrostatic chuck of the present invention will be sequentially described in detail. To go.

The ceramic dielectric film used in the electrostatic chuck of the present invention is preferably made of a nitride ceramic. Examples of the nitride ceramic include those similar to the ceramic substrate. It is desirable that the nitride ceramic contains oxygen. In this case, the sintering of the nitride ceramic proceeds easily, and even when the nitride ceramic contains pores, the pores become independent pores, and the withstand voltage is improved.

In order to make the above-mentioned nitride ceramic contain oxygen, usually, a metal oxide is mixed into a raw material powder of the nitride ceramic and firing is performed. Examples of the metal oxide include alumina (Al ₂ O ₃ ) and silicon oxide (SiO ₂ ). The addition amount of these metal oxides is preferably 0.1 to 10 parts by weight based on 100 parts by weight of the nitride ceramic.

By setting the thickness of the ceramic dielectric film to 50 to 5000 μm, a sufficient withstand voltage can be secured without reducing the chucking force. If the thickness of the ceramic dielectric film is less than 50 μm, a sufficient withstand voltage cannot be obtained because the film thickness is too small, and the dielectric breakdown of the ceramic dielectric film occurs when a silicon wafer is placed and adsorbed. On the other hand, when the thickness of the ceramic dielectric film exceeds 5000 μm, the distance between the silicon wafer and the electrostatic electrode is increased, and the ability to adsorb the silicon wafer is reduced. The thickness of the ceramic dielectric film is preferably 100 to 1500 μm.

The porosity of the ceramic dielectric film is preferably 5% or less, and the pore diameter of the largest pore is preferably 50 μm or less. When the porosity exceeds 5%, the number of pores increases, and the pore diameter becomes too large. As a result, the pores easily communicate with each other. With a ceramic dielectric film having such a structure, the withstand voltage decreases. Further, when the pore diameter of the maximum pore exceeds 50 μm, withstand voltage at high temperature cannot be ensured even if the oxide exists at the grain boundary. The porosity is preferably from 0.01 to 3%, and the pore diameter of the maximum pore is preferably from 0.1 to 10 μm.

It is desirable that the ceramic dielectric film contains 50 to 5000 ppm of carbon. This is because the electrode pattern provided in the electrostatic chuck can be concealed and high radiation heat can be obtained. Also, the lower the volume resistivity, the higher the silicon wafer adsorption capacity in a low temperature range.

In the present invention, the reason that a certain amount of pores may exist in the ceramic dielectric film is that the fracture toughness value can be increased, thereby improving the thermal shock resistance. .

Examples of the electrostatic electrode include a sintered body of metal or conductive ceramic, a metal foil, and the like. The metal sintered body is preferably made of at least one selected from tungsten and molybdenum. It is desirable that the metal foil is also made of the same material as the metal sintered body. This is because these metals are relatively hard to oxidize and have sufficient conductivity as electrodes. As the conductive ceramic, at least one selected from carbides of tungsten and molybdenum can be used.

9 and 10 are horizontal cross-sectional views schematically showing electrostatic electrodes in another electrostatic chuck. In the electrostatic chuck 20 shown in FIG. 9, a semicircular chuck positive electrode is provided inside the ceramic substrate 1. An electrostatic layer 22 and a chuck negative electrode electrostatic layer 23 are formed. In the electrostatic chuck shown in FIG. 10, chuck positive electrode electrostatic layers 32a and 32b each having a shape obtained by dividing a circle into four inside a ceramic substrate 1 and a chuck negative electrode. Electrostatic layers 33a and 33b are formed. Further, the two positive electrode electrostatic layers 22a and 22b and the two chuck negative electrode electrostatic layers 33a and 33b are formed so as to cross each other. In the case of forming an electrode in which a circular electrode or the like is divided, the number of divisions is not particularly limited, and may be five or more, and the shape is not limited to a sector.

As shown in FIG. 3, for example, as shown in FIG. 3, a chuck positive electrostatic layer 2 and a chuck negative electrostatic layer 3 are provided between a ceramic substrate 1 and a ceramic dielectric film 4. An electrostatic chuck 101 having a structure in which a resistance heating element 5 is provided inside a substrate 1. As shown in FIG. 5, a chuck positive electrostatic layer 2 and a chuck negative electrode are provided between a ceramic substrate 1 and a ceramic dielectric film 4. An electrostatic chuck 201 having a structure in which an electrostatic layer 3 is provided and a resistance heating element 25 is provided on the bottom surface of the ceramic substrate 1, as shown in FIG. 6, between the ceramic substrate 1 and the ceramic dielectric film 4. An electrostatic chuck 301 having a configuration in which a chuck positive electrode electrostatic layer 2 and a chuck negative electrode electrostatic layer 3 are provided and a metal wire 7 serving as a resistance heating element is embedded inside a ceramic substrate 1, as shown in FIG. Cerami The chuck positive electrode electrostatic layer 2 and the chuck negative electrode electrostatic layer 3 are provided between the ceramic substrate 1 and the ceramic dielectric film 4, and a Peltier element 8 composed of a thermoelectric element 81 and a ceramic plate 82 is provided on the bottom surface of the ceramic substrate 1. An example of the formed structure is an electrostatic chuck 401.

In the present invention, as shown in FIGS. 3 to 7, the chuck positive electrostatic layer 2 and the chuck negative electrostatic layer 3 are provided between the ceramic substrate 1 and the ceramic dielectric film 4. Since the resistance heating element 5 and the metal wire 7 are formed on the substrate, connecting portions (through holes) 16 and 17 for connecting these to external terminals are required. The through holes 16 and 17 are formed by filling a high melting point metal such as a tungsten paste or a molybdenum paste or a conductive ceramic such as tungsten carbide or molybdenum carbide.

The diameter of the connection portions (through holes) 16 and 17 is preferably 0.1 to 10 mm. This is because cracks and distortion can be prevented while preventing disconnection. The external terminals 6 and 18 are connected using the through holes as connection pads (see FIG. 8D).

Connection is made with solder or brazing material. As the brazing material, silver brazing, palladium brazing, aluminum brazing, or gold brazing is used. As the gold solder, an Au-Ni alloy is desirable. This is because the Au-Ni alloy has excellent adhesion to tungsten.

The ratio of Au / Ni is desirably [81.5 to 82.5 (% by weight)] / [18.5 to 17.5 (% by weight)]. The thickness of the Au—Ni layer is desirably 0.1 to 50 μm. This is because the range is sufficient to secure the connection. When used in a high vacuum of 10 ^-6 to 10 ^-5 Pa at a high temperature of 500 to 1000 ° C., the Au—Cu alloy deteriorates, but the Au—Ni alloy has no such deterioration and is advantageous. The amount of the impurity element in the Au—Ni alloy is desirably less than 1 part by weight when the total amount is 100 parts by weight.

In the present invention, a thermocouple can be embedded in the bottomed hole of the ceramic substrate as needed. This is because the temperature of the resistance heating element can be measured with a thermocouple, and the voltage and current amount can be changed based on the data to control the temperature. The size of the joining part of the metal wires of the thermocouple is preferably equal to or larger than the wire diameter of each metal wire and 0.5 mm or less. With such a configuration, the heat capacity of the junction is reduced, and the temperature is accurately and quickly converted to a current value. For this reason, the temperature controllability is improved, and the temperature distribution on the heated surface of the wafer is reduced. Examples of the thermocouple include K-type, R-type, B-type, S-type, E-type, J-type, and T-type thermocouples as described in JIS-C-1602 (1980).

FIG. 11 is a cross-sectional view schematically showing a supporting container 41 for fitting the electrostatic chuck of the present invention having the above configuration. The electrostatic chuck 101 is fitted into the support container 41 via a heat insulating material 45. Further, the support container 11 is formed with a refrigerant outlet 42, the refrigerant is blown from the refrigerant inlet 44, and passes through the refrigerant outlet 42 and exits from the suction port 43. By the action of the refrigerant, the electrostatic chuck 101 can be cooled.

Next, an example of a method for manufacturing an electrostatic chuck, which is an example of the ceramic substrate of the present invention, will be described with reference to the cross-sectional views shown in FIGS.
(1) First, a green sheet 50 is obtained by mixing a ceramic powder such as a nitride ceramic or a carbide ceramic with a binder and a solvent. As the above-mentioned ceramic powder, for example, aluminum nitride powder containing oxygen obtained by firing in an oxidizing atmosphere can be used. If necessary, a sintering aid such as alumina, silica, sulfur or the like, or a catalyst may be added.

Note that several or one green sheet 50 ′ to be laminated on the green sheet on which the electrostatic electrode layer printed body 51 described later is formed is a layer to be the ceramic dielectric film 4. The composition may be different from that of the substrate. Usually, it is desirable to use the same material for the ceramic dielectric film 4 and the material for the ceramic substrate 1. This is because these are often sintered integrally, and the firing conditions are the same. However, when the materials are different, a ceramic substrate may be manufactured first, an electrostatic electrode layer may be formed thereon, and a ceramic dielectric film may be formed thereon.

The binder is preferably at least one selected from an acrylic binder, ethyl cellulose, butyl cellosolve, and polyvinyl alcohol. Further, as the solvent, at least one selected from α-terpineol and glycol is desirable. A paste obtained by mixing these is formed into a sheet by a doctor blade method to produce a green sheet 50.

If necessary, the green sheet 50 may be provided with through holes for inserting support pins of the silicon wafer, recesses for burying thermocouples, portions for forming through holes, and the like. The through holes can be formed by punching or the like. The thickness of the green sheet 50 is preferably about 0.1 to 5 mm.

Next, a conductive paste is filled in the through holes of the green sheet 50 to obtain through-hole prints 53 and 54, and then a conductive paste serving as an electrostatic electrode layer and a resistance heating element is printed on the green sheet 50. The printing is performed so as to obtain a desired aspect ratio in consideration of the shrinkage ratio of the green sheet 50, thereby obtaining the electrostatic electrode layer print body 51 and the resistance heating element layer print body 52. The printed body is formed by printing a conductive paste containing conductive ceramic, metal particles, and the like.

As the conductive ceramic particles contained in these conductive pastes, carbides of tungsten or molybdenum are most suitable. This is because it is difficult to be oxidized and the thermal conductivity is not easily reduced. Further, as the metal particles, for example, tungsten, molybdenum, platinum, nickel and the like can be used.

The average particle diameter of the conductive ceramic particles and the metal particles is preferably 0.1 to 5 μm. This is because it is difficult to print the conductor paste when these particles are too large or too small. As such a paste, 85 to 97 parts by weight of metal particles or conductive ceramic particles, 1.5 to 10 parts by weight of at least one binder selected from acrylic, ethyl cellulose, butyl cellosolve and polyvinyl alcohol, α-terpineol, glycol A paste for a conductor prepared by mixing 1.5 to 10 parts by weight of at least one solvent selected from ethyl alcohol and butanol is most suitable.

Next, as shown in FIG. 8A, a green sheet 50 having prints 51, 52, 53 and 54 and a green sheet 50 'having no print are laminated. The reason why the green sheet 50 'having no printed body is laminated on the resistance heating element formation side is to prevent the end face of the through hole from being exposed and being oxidized at the time of firing for forming the resistance heating element. is there. If baking for forming the resistance heating element is performed while the end face of the through hole is exposed, it is necessary to sputter a hardly oxidizable metal such as nickel, and more preferably, to coat with Au-Ni gold solder. Is also good.

(2) Next, as shown in FIG. 8B, the laminate is heated and pressed to sinter the green sheet and the conductive paste. The heating temperature is preferably from 1000 to 2000 ° C., and the pressurization is preferably from 100 to 200 kg / cm ² , and the heating and pressurization are performed in an inert gas atmosphere. As the inert gas, argon, nitrogen, or the like can be used. In this step, the through holes 16 and 17, the chuck positive electrode electrostatic layer 2, the chuck negative electrode electrostatic layer 3, the resistance heating element 5, and the like are formed.

(3) Next, as shown in FIG. 8C, blind holes 35 and 36 for connecting external terminals are provided. At least a part of the inner walls of the blind holes 35 and 36 is conductive, and the conductive inner walls are connected to the chuck positive electrostatic layer 2, the chuck negative electrostatic layer 3, the resistance heating element 5, and the like. It is desirable.

(7) Finally, as shown in FIG. 8 (d), external terminals 6, 18 are provided in the blind holes 35, 36 via gold brazing. Further, if necessary, a bottomed hole 12 can be provided, and a thermocouple can be embedded therein. As the solder, alloys such as silver-lead, lead-tin, and bismuth-tin can be used. Note that the thickness of the solder layer is desirably 0.1 to 50 μm. This is because the range is sufficient to secure the connection by soldering.

In the above description, the electrostatic chuck 101 (see FIG. 3) is taken as an example. However, when manufacturing the electrostatic chuck 201 (see FIG. 5), after manufacturing a ceramic plate having an electrostatic electrode layer, A conductive paste may be printed and fired on the bottom surface of the plate to form the resistance heating element 25, and then the metal layer 25a may be formed by electroless plating or the like. When the electrostatic chuck 301 (see FIG. 6) is manufactured, a metal foil or a metal wire may be embedded in a ceramic powder as an electrostatic electrode or a resistance heating element and sintered. Further, when manufacturing the electrostatic chuck 401 (see FIG. 7), after manufacturing a ceramic plate having an electrostatic electrode layer, a Peltier element may be joined to the ceramic plate via a sprayed metal layer.

Conductors are disposed on the surface and inside of the ceramic substrate of the present invention, when the conductor layer on the surface is a chuck top conductor layer and the conductor inside is at least one of a guard electrode or a ground electrode, The ceramic substrate functions as a wafer prober.

FIG. 12 is a cross-sectional view schematically showing an embodiment of the wafer prober of the present invention, and FIG. 13 is a cross-sectional view taken along line AA of the wafer prober shown in FIG.
In the wafer prober 501, a concentric groove 67 in plan view is formed on the surface of the disc-shaped ceramic substrate 63, and a plurality of suction holes 68 for sucking a silicon wafer are provided in a part of the groove 67. A chuck top conductor layer 62 for connecting to an electrode of a silicon wafer is formed in a circular shape on most of the ceramic substrate 63 including the groove 67.

On the other hand, a heating element 61 having a concentric circular shape in plan view as shown in FIG. 1 is provided on the bottom surface of the ceramic substrate 63 in order to control the temperature of the silicon wafer. Terminals (not shown) are connected and fixed. Further, inside the ceramic substrate 63, a guard electrode 65 and a ground electrode 66 (see FIG. 13) having a lattice shape in plan view are provided for removing stray capacitors and noise. The materials of the guard electrode 65 and the ground electrode 66 may be the same as those of the electrostatic electrode.

The thickness of the chuck top conductor layer 62 is desirably 1 to 20 μm. If the thickness is less than 1 μm, the resistance value is too high to act as an electrode.

As the chuck top conductor layer 62, for example, at least one kind of metal selected from high melting point metals such as copper, titanium, chromium, nickel, noble metals (gold, silver, platinum, etc.), tungsten, and molybdenum can be used. .

In such a wafer prober, a silicon wafer on which an integrated circuit is formed is placed thereon, and a probe card having tester pins is pressed against the silicon wafer, and a voltage is applied while heating and cooling to conduct a continuity test. It can be performed. In the case of manufacturing a wafer prober, for example, similarly to the case of an electrostatic chuck, first, a ceramic substrate in which a resistance heating element is embedded is manufactured, and then, a groove is formed on the surface of the ceramic substrate, and then, Then, a metal layer may be formed by performing sputtering, plating, or the like on the surface portion where the groove is formed.

Hereinafter, the present invention will be described in more detail.
(Example 1) Production of electrostatic chuck (see FIG. 3) (1) 1000 parts by weight of aluminum nitride powder (manufactured by Tokuyama Corporation, average particle size 1.1 μm) fired at 500 ° C. for 1 hour in air, alumina (average) 20 parts by weight, 115 parts by weight of acrylic binder, 0.07 parts by weight of CaS, 0.03 parts by weight of silica, 5 parts by weight of dispersant, and 530 parts by weight of alcohol composed of 1-butanol and ethanol Was molded by a doctor blade method using a paste obtained by mixing the above, to obtain a green sheet having a thickness of 0.47 mm.

(2) Next, after drying the green sheet at 80 ° C. for 5 hours, a portion to be a through hole for inserting a semiconductor wafer support pin having a diameter of 1.8 mm, 3.0 mm, or 5.0 mm by punching, an external terminal And a portion serving as a through hole for connection to the substrate.

(3) 100 parts by weight of tungsten carbide particles having an average particle diameter of 1 μm, 3.0 parts by weight of an acrylic binder, 3.5 parts by weight of an α-terpineol solvent, and 0.3 part by weight of a dispersant are mixed to form a conductive paste A. Prepared. A conductive paste B was prepared by mixing 100 parts by weight of tungsten particles having an average particle diameter of 3 μm, 1.9 parts by weight of an acrylic binder, 3.7 parts by weight of an α-terpineol solvent, and 0.2 parts by weight of a dispersant. The conductive paste A was printed on a green sheet by screen printing to form a conductive paste layer. The printing pattern was a concentric pattern. Further, a conductor paste layer composed of an electrostatic electrode pattern having the shape shown in FIG. 4 was formed on another green sheet.

Further, a conductive paste B was filled in a through hole for a through hole for connecting an external terminal. On the green sheet 50 after the above processing, 34 green sheets 50 ′ on which no tungsten paste is printed are laminated on the upper side (heating surface) and 13 green sheets 50 ′ are laminated on the lower side, and a conductor paste composed of an electrostatic electrode pattern is formed thereon. The green sheet 50 on which the layers are printed is laminated, and two green sheets 50 ′ on which the tungsten paste is not printed are further laminated thereon, and these are pressed at 130 ° C. under a pressure of 80 kg / cm ² to form a laminate. It was formed (FIG. 7A).

(4) Next, the obtained laminate was degreased in nitrogen gas at 600 ° C. for 5 hours and hot-pressed at 1890 ° C. and a pressure of 150 kg / cm ² for 3 hours to obtain a 3 mm-thick aluminum nitride plate. Was. This was cut out into a disk shape of 230 mm, and a plate-shaped body made of aluminum nitride having therein a resistance heating element 5 having a thickness of 6 μm and a width of 10 mm, and a chuck positive electrostatic layer 2 and a chuck negative electrostatic layer 3 having a thickness of 10 μm. (FIG. 7B).

(5) Next, the plate-like body obtained in (4) is polished with a diamond grindstone, a mask is placed, and a blasting treatment with SiC or the like is performed on the surface to form a bottomed hole for a thermocouple (diameter: 1.2 mm, depth: 2.0 mm).

(6) Further, the portions where the through holes are formed are cut out to form blind holes 35 and 36 (FIG. 7 (c)), and a gold solder made of Ni-Au is used for the blind holes 35 and 36 at 700 ° C. And the external terminals 6 and 18 made of Kovar were connected (FIG. 7D). The connection of the external terminals is desirably a structure in which a tungsten support is supported at three points. This is because connection reliability can be ensured.

(7) Next, a plurality of thermocouples for temperature control were buried in the bottomed holes, and the manufacture of the electrostatic chuck having a resistance heating element was completed.

(Example 2) Production of electrostatic chuck (see FIG. 5) (1) 1000 parts by weight of aluminum nitride powder (manufactured by Tokuyama Corporation, average particle size 1.1 μm) fired in air at 500 ° C. for 1 hour, alumina (average) Particle size: 0.4 μm) Doctor using a paste obtained by mixing 20 parts by weight, 115 parts by weight of acrylic binder, 0.03 parts by weight of silica, 5 parts by weight of dispersant, and 530 parts by weight of alcohol composed of 1-butanol and ethanol. The green sheet having a thickness of 0.47 mm was obtained by molding by a blade method.

(2) Next, after drying the green sheet at 80 ° C. for 5 hours, a portion to be a through hole for inserting a semiconductor wafer support pin having a diameter of 1.8 mm, 3.0 mm, or 5.0 mm by punching, an external terminal And a portion serving as a through hole for connection to the substrate.

(3) 100 parts by weight of tungsten carbide particles having an average particle diameter of 1 μm, 3.0 parts by weight of an acrylic binder, 3.5 parts by weight of an α-terpineol solvent, and 0.3 part by weight of a dispersant are mixed to form a conductive paste A. Prepared. A conductive paste B was prepared by mixing 100 parts by weight of tungsten particles having an average particle diameter of 3 μm, 1.9 parts by weight of an acrylic binder, 3.7 parts by weight of an α-terpineol solvent, and 0.2 parts by weight of a dispersant. The conductive paste A was printed on a green sheet by screen printing to form a conductive paste layer having an electrostatic electrode pattern having the shape shown in FIG.

Further, a conductive paste B was filled in a through hole for a through hole for connecting an external terminal. On the green sheet 50 after the above processing, one green sheet 50 'on which no tungsten paste is printed is further laminated on the upper side (heating surface) and 48 on the lower side, and these are laminated at 130 ° C. and a pressure of 80 kg / cm ² . To form a laminate.

(4) Next, the obtained laminate was degreased in nitrogen gas at 600 ° C. for 5 hours and hot-pressed at 1890 ° C. and a pressure of 150 kg / cm ² for 3 hours to obtain a 3 mm-thick aluminum nitride plate. Was. This was cut into a disk shape of 230 mm, and a plate-shaped body made of aluminum nitride having a 15 μm-thick chuck positive electrode electrostatic layer 2 and a chuck negative electrode electrostatic layer 3 inside.

(5) A mask was placed on the bottom surface of the plate obtained in the above (4), and a concave portion (not shown) for a thermocouple was provided on the surface by blasting with SiC or the like.

(6) Next, a conductor paste for forming a resistance heating element was printed on the surface (bottom surface) facing the wafer mounting surface. As the conductive paste, Solvest PS603D manufactured by Tokuri Chemical Laboratory, which is used for forming through holes in a printed wiring board, was used. This conductive paste is a silver / lead paste, and a metal oxide composed of lead oxide, zinc oxide, silica, boron oxide, and alumina (the weight ratio of each is 5/55/10/25/5) is 100 weight of silver. Parts by weight. The silver had a scaly shape with an average particle size of 4.5 μm.

(7) The plate-like body on which the conductive paste was printed was heated and fired at 780 ° C. to sinter silver and lead in the conductive paste and to bake the ceramic paste on the ceramic substrate. Further, the plate is immersed in an electroless nickel plating bath comprising an aqueous solution containing 30 g / l of nickel sulfate, 30 g / l of boric acid, 30 g / l of ammonium chloride and 60 g / l of Rochelle salt, and the surface of the silver sintered body 25 is immersed. Then, a metal layer 25a made of nickel having a thickness of 1 μm and a boron content of 1% by weight or less was deposited. Thereafter, the plate was subjected to annealing at 120 ° C. for 3 hours. The resistance heating element made of a silver sintered body had a thickness of 5 μm, a width of 2.4 mm, and an area resistivity of 7.7 mΩ / □.

(8) Next, a blind hole for exposing the through hole 16 was provided in the ceramic substrate. An external terminal made of Kovar was connected to the blind hole by heating and reflowing at 970 ° C. using a gold solder made of a Ni—Au alloy (81.5% by weight of Au, 18.4% by weight of Ni, and 0.1% by weight of impurities). Was. External terminals made of Kovar were formed on the resistance heating element via solder (tin 9 / lead 1).

(9) Next, a plurality of thermocouples for temperature control were buried in the concave portions to obtain the electrostatic chuck 201.

(10) Next, this electrostatic chuck 201 was fitted into a stainless steel support container 41 having a cross-sectional shape shown in FIG. 11 via a heat insulating material 45 made of ceramic fiber (trade name: IBIWOOL, manufactured by IBIDEN). The support container 41 has a cooling gas outlet 42 for cooling gas, and the temperature of the electrostatic chuck 201 can be adjusted. The resistance heating element 25 of the electrostatic chuck 201 fitted in the support container 41 was energized to increase the temperature, and the coolant was passed through the support container to control the temperature of the electrostatic chuck 201. Temperature could be controlled.

Example 3 Production of Electrostatic Chuck 301 (FIG. 6) (1) Two electrodes having the shape shown in FIG. 9 were formed by punching a 10 μm-thick tungsten foil. 45 parts by weight of silicon nitride powder (average particle size 1.1 μm), 15 parts by weight of Al ₂ O ₃ (average particle size 0.5 μm) Along with 40 parts by weight of SiO ₂ (average particle size: 0.5 μm) and 8 parts by weight of an acrylic resin binder (SA-545 manufactured by Mitsui Chemicals, acid value: 1.0), the mixture was put in a mold at 1890 ° C. and pressure in nitrogen gas. Hot pressing was performed at 150 kg / cm ² for 3 hours to obtain a 3 mm-thick aluminum nitride plate. This was cut into a disk having a diameter of 230 mm to obtain a plate-like body. At this time, the thickness of the electrostatic electrode layer was 10 μm.

(2) The steps (5) to (7) of Example 1 were performed on this plate to obtain an electrostatic chuck 301.

Example 4 After performing the steps (1) to (5) of Example 2 of manufacturing the electrostatic chuck 401 (FIG. 7), nickel was further sprayed on the bottom surface, and then a lead / tellurium Peltier was used. By joining the elements, an electrostatic chuck 401 was obtained. The thus manufactured electrostatic chuck was excellent in temperature-fall characteristics, and when cooled with a Peltier element, the temperature dropped from 450 ° C. to 100 ° C. in 3 minutes.

(Example 5) Production of wafer prober 501 (see FIG. 12) (1) 1000 parts by weight of aluminum nitride powder (manufactured by Tokuyama Corporation, average particle size 1.1 μm), 20 parts by weight of alumina (average particle size: 0.4 μm) Using a paste obtained by mixing 115 parts by weight of an acrylic binder, 5 parts by weight of polyether sulfone, 0.03 parts by weight of silica, 5 parts by weight of a dispersant, and 530 parts by weight of alcohol composed of 1-butanol and ethanol by a doctor blade method. The molding was performed to obtain a green sheet having a thickness of 0.47 mm.

(2) Next, after drying the green sheet at 80 ° C. for 5 hours, a through-hole for a through-hole for connecting the heating element to an external terminal was provided by punching.

(3) 100 parts by weight of tungsten carbide particles having an average particle diameter of 1 μm, 3.0 parts by weight of an acrylic binder, 3.5 parts by weight of an α-terpineol solvent, and 0.3 part by weight of a dispersant were mixed to form a conductive paste A. . Further, 100 parts by weight of tungsten particles having an average particle diameter of 3 μm, 1.9 parts by weight of an acrylic binder, 3.7 parts by weight of an α-terpineol solvent, and 0.2 parts by weight of a dispersant were mixed to form a conductive paste B. .

Next, a grid-shaped printed body for a guard electrode and a printed body for a ground electrode were printed on the green sheet by screen printing using the conductive paste A. Further, a conductive paste B was filled in a through hole for a through hole for connecting to an external terminal.

Further, 50 printed green sheets and unprinted green sheets were laminated and integrated at 130 ° C. under a pressure of 80 kg / cm ² to produce a laminate.

(4) Next, the laminate was degreased in nitrogen gas at 600 ° C. for 5 hours, and hot-pressed at 1890 ° C. and a pressure of 150 kg / cm ² for 3 hours to obtain an aluminum nitride plate having a thickness of 3 mm. The obtained plate was cut into a circular shape having a diameter of 300 mm to obtain a ceramic plate. The size of the through hole 16 was 0.2 mm in diameter and 0.2 mm in depth.

The thickness of the guard electrode 65 and the ground electrode 66 was 10 μm, the formation position of the guard electrode 65 was 1 mm from the wafer mounting surface, and the formation position of the ground electrode 66 was 1.2 mm from the wafer mounting surface. The size of one side of the conductor non-forming region 66a of the guard electrode 65 and the ground electrode 66 was 0.5 mm.

(5) After polishing the plate-like body obtained in the above (4) with a diamond grindstone, a mask is placed, and a concave portion for a thermocouple and a groove 67 for wafer adsorption (see FIG. (Width 0.5 mm, depth 0.5 mm).

(6) Further, a layer for forming the heating element 61 was printed on the surface facing the wafer mounting surface. For printing, a conductive paste was used. As the conductive paste, Solvest PS603D manufactured by Tokuri Chemical Laboratory, which is used for forming through holes in a printed wiring board, was used. This conductive paste is a silver / lead paste, and a metal oxide composed of lead oxide, zinc oxide, silica, boron oxide, and alumina (the weight ratio of each is 5/55/10/25/5) is 100 weight of silver. Parts by weight. The silver had a scaly shape with an average particle size of 4.5 μm.

(7) The ceramic substrate on which the conductive paste was printed was heated and fired at 780 ° C. to sinter silver and lead in the conductive paste and to bake the ceramic substrate 63. Further, the heater plate is immersed in an electroless nickel plating bath composed of an aqueous solution containing 30 g / l of nickel sulfate, 30 g / l of boric acid, 30 g / l of ammonium chloride and 60 g / l of Rochelle salt, to generate a resistance heating made of a silver sintered body. A nickel layer (not shown) having a thickness of 1 μm and a boron content of 1% by weight or less was deposited on the surface of the body 61. Thereafter, the heater plate was subjected to annealing at 120 ° C. for 3 hours. The heating element made of a silver sintered body had a thickness of 5 μm, a width of 2.4 mm, and a sheet resistivity of 7.7 mΩ / □.

(8) A titanium layer, a molybdenum layer, and a nickel layer were sequentially formed on the surface on which the grooves 67 were formed by a sputtering method. As a device for sputtering, SV-4540 manufactured by Japan Vacuum Engineering Co., Ltd. was used. The sputtering conditions were as follows: atmospheric pressure: 0.6 Pa, temperature: 100 ° C., power: 200 W. Sputtering time was adjusted for each metal within a range of 30 seconds to 1 minute. The thickness of the obtained film was 0.3 μm for the titanium layer, 2 μm for the molybdenum layer, and 1 μm for the nickel layer from the image of the X-ray fluorescence spectrometer.

(9) The ceramic plate obtained in the above (8) is immersed in an electroless nickel plating bath composed of an aqueous solution containing 30 g / l of nickel sulfate, 30 g / l of boric acid, 30 g / l of ammonium chloride and 60 g / l of Rochelle salt. A nickel layer having a thickness of 7 μm and a boron content of 1% by weight or less was deposited on the surface of the metal layer formed by sputtering, and annealed at 120 ° C. for 3 hours. The surface of the heating element does not pass a current and is not covered with electrolytic nickel plating.

Further, the surface is immersed in an electroless gold plating solution containing 2 g / l of potassium gold cyanide, 75 g / l of ammonium chloride, 50 g / l of sodium citrate and 10 g / l of sodium hypophosphite at 93 ° C. for 1 minute. Then, a gold plating layer having a thickness of 1 μm was formed on the nickel plating layer.

(10) A suction hole 68 for air that escapes from the groove 67 to the back surface is formed by drilling, and a blind hole (not shown) for exposing the through hole 16 is provided. An external terminal made of Kovar was connected to the blind hole by heating and reflowing at 970 ° C. using a gold solder made of a Ni—Au alloy (81.5% by weight of Au, 18.4% by weight of Ni, and 0.1% by weight of impurities). Was. External terminals made of Kovar were formed on the heating element via solder (tin 90% by weight / lead 10% by weight).

(11) Next, a plurality of thermocouples for temperature control were buried in the recesses to obtain a wafer prober heater 201 with a heater. When the temperature of the wafer prober with a heater was raised to 200 ° C., the temperature was raised to 200 ° C. in about 20 seconds.

(Example 6)
An electrostatic chuck was manufactured in the same manner as in Example 1, except that the size of the electrostatic chuck was 330 mm in diameter and 3 mm in thickness.

(Comparative Example 1)
(1) 100 parts by weight of aluminum nitride powder (manufactured by Tokuyama Corporation, average particle size 1.1 μm), 4 parts by weight of yttria (average particle size: 0.4 μm), 11.5 parts by weight of acrylic binder, 0.5 part by weight of dispersant Part and a paste obtained by mixing 53 parts by weight of alcohol composed of 1-butanol and ethanol, and molded by a doctor blade method to obtain a green sheet 50 having a thickness of 0.47 mm, except that a green sheet 50 having a thickness of 0.47 mm was obtained. Thus, an electrostatic chuck was manufactured.

(Comparative Example 2)
An electrostatic chuck was manufactured in the same manner as in Example 2, except that the aluminum nitride powder was not fired in air and silica and the like were not added. The oxygen content in the aluminum nitride powder is estimated to be 0.01% by weight. The surface of such a sintered body was polished and observed with an electron microscope (SEM), but almost no boundaries between crystal grains were found. However, there was a grain boundary fracture in the fracture cross section.

(Comparative Example 3)
An electrostatic chuck was manufactured in the same manner as in Example 2 except that 4 parts by weight of yttria was added.

(Comparative Example 4)
An electrostatic chuck was manufactured in the same manner as in Comparative Example 1, except that the size of the electrostatic chuck was 330 mm in diameter and 3 mm in thickness.

(Comparative Example 5)
An electrostatic chuck was manufactured in the same manner as in Comparative Example 2, except that the size of the electrostatic chuck was 330 mm in diameter and 3 mm in thickness.

(Test example)
An electrostatic chuck was manufactured in the same manner as in Example 1, except that the firing time of aluminum nitride was further changed to 10 hours.

The following indexes were used to evaluate the electrostatic chucks and wafer probers according to Examples 1 to 6, Comparative Examples 1 to 5, and Test Examples obtained through the above steps.

Evaluation method (1) Observation of fracture cross section The fracture cross section was observed at 2000 times with an electron microscope, and it was confirmed whether it was intraparticle fracture. FIG. 14 is a scanning electron microscope (SEM) photograph of the fracture cross section of Example 1, and FIG. 15 is a SEM photograph of the fracture cross section of Comparative Example 1.

(2) Particle Count After the wafer was chucked by the electrostatic chuck, an arbitrary 10 places on the wafer were observed and photographed with an electron microscope, the number of particles having a particle diameter of 0.2 μm or more was counted, and the number was divided by the photographing visual field area.

(3) Measurement of Strength The strength was measured using an Instron universal tester (type 4507 load cell 500 kgf) in the air at a temperature of 400 ° C. and 200 ° C. (Example 5) at a crosshead speed of 0.5 mm / min. , The span distance L: 30 mm, the thickness of the test piece: 3.06 mm, the width of the test piece: 4.03 mm, and the three-point bending strength σ (kgf / mm ² ) using the following formula (1). Was calculated. In Table 1, the units are converted and expressed in MPa.

σ = 3PL / 2wt ² ··· (1)

In the above formula (1), P is the maximum load (kgf) when the test piece breaks, L is the distance between lower supports (30 mm), and t is the thickness (mm) of the test piece. ), And w is the width (mm) of the test piece.

(4) Oxygen Amount Pulverized in a tungsten mortar to collect 0.01 g, and analyzed by a simultaneous oxygen / nitrogen analyzer under the conditions of a heating temperature of 2200 ° C. and a heating time of 30 seconds.

(5) Warpage Amount was measured by a laser displacement meter after the temperature was raised to 600 ° C. in vacuum. The measurement was performed in a range of a diameter of -10 mm.

As is clear from the SEM photographs shown in FIGS. 14 and 15, the ceramic substrate constituting the electrostatic chuck according to Example 1 has a cross section of intra-particle fracture, and constitutes the electrostatic chuck of Comparative Example 1. In the case of a ceramic substrate, the cross section has a grain boundary fracture. Further, as is clear from Table 1, the electrostatic chucks with hot plates according to Examples 1 to 6 also have excellent bending strength at high temperatures and a small number of particles on the silicon wafer mounted on the electrostatic chuck. .

Although the reason why the bending strength at high temperature is high is not clear, it is presumed that the presence of impurities such as oxygen at the grain boundaries is small, and apparent defects are small. Further, the fracture cross section does not need to be entirely intra-particle fracture, and may be mostly intra-particle fracture as shown by an electron microscope (FIG. 14), and may include particle boundary fracture.

It is a top view which shows typically an example of the ceramic heater using the ceramic substrate of this invention. FIG. 2 is a partially enlarged sectional view of the ceramic heater shown in FIG. 1. It is sectional drawing which shows typically an example of the electrostatic chuck using the ceramic substrate of this invention. FIG. 4 is a sectional view taken along line AA of the ceramic heater shown in FIG. 3. It is sectional drawing which shows typically an example of the electrostatic chuck using the ceramic substrate of this invention. It is sectional drawing which shows typically an example of the electrostatic chuck using the ceramic substrate of this invention. It is sectional drawing which shows typically an example of the electrostatic chuck using the ceramic substrate of this invention. (A)-(d) is sectional drawing which shows typically a part of manufacturing process of the electrostatic chuck shown in FIG. FIG. 3 is a horizontal cross-sectional view schematically showing the shape of an electrostatic electrode constituting the electrostatic chuck according to the present invention. FIG. 3 is a horizontal cross-sectional view schematically showing the shape of an electrostatic electrode constituting the electrostatic chuck according to the present invention. FIG. 4 is a cross-sectional view schematically illustrating a state where the electrostatic chuck according to the present invention is fitted into a support container. FIG. 3 is a cross-sectional view schematically showing a wafer prober using the ceramic substrate of the present invention. FIG. 13 is a cross-sectional view schematically showing a guard electrode of the wafer prober shown in FIG. 5 is an SEM photograph showing a fracture cross section of a ceramic substrate constituting the electrostatic chuck according to Example 1. 5 is an SEM photograph showing a fracture cross section of a ceramic substrate constituting an electrostatic chuck according to Comparative Example 1.

Explanation of reference numerals

1, 11, 63 Ceramic substrates 2, 22, 32a, 32b Chuck positive electrode electrostatic layers 3, 23, 33a, 33b Chuck negative electrode electrostatic layers 2a, 3a Semicircular portions 2b, 3b Comb portions 4 Ceramic dielectric film 5 , 12, 25, 61 Resistance heating elements 6, 13, 18 External terminals 7 Metal wires 8 Peltier elements 9 Silicon wafers 10 Ceramic heaters 14 Bottomed holes 15 Through holes 16, 17, 19 Through holes 20, 30, 101, 201, 301, 401 Electrostatic chuck 25a Metal coating layer 35, 36 Bag hole 41 Support container 42 Refrigerant outlet 43 Inlet 44 Refrigerant inlet 45 Insulation material 62 Chuck top conductor layer 65 Guard electrode 66 Ground electrode 66a No electrode formation region 67 Groove 68 Suction hole 501 Wafer prober

Claims (4)

A ceramic substrate for a semiconductor manufacturing / inspection apparatus in which a conductor is formed on the surface or inside of a ceramic substrate,
A ceramic substrate for a semiconductor manufacturing / inspection apparatus, wherein the ceramic substrate is sintered so that its fracture cross section is broken into particles. The ceramic substrate for a semiconductor manufacturing / inspection apparatus according to claim 1, wherein the ceramic substrate is made of a nitride ceramic containing oxygen. The ceramic substrate for a semiconductor manufacturing / inspection device according to claim 1, wherein the ceramic substrate has a warpage of 100 μm or less. The ceramic substrate for a semiconductor manufacturing / inspection apparatus according to claim 1, wherein the ceramic substrate is used at 100 to 800 ° C. 5.

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