JP2005022966A - Aluminum nitride joined body and its producing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joined structural body which is a plate joined body being useful as a plate heater or an electrostatic chuck to process a mounted semiconductor wafer and consisting of an aluminum nitride sintered body joined through a metal layer, which can process the semiconductor wafer uniformly when used for the above mentioned uses and which has excellent durability. <P>SOLUTION: The plate joined body of the aluminum nitride sintered body is intervened by the metal layer for a part of a joined plane. The joining between the aluminum nitride sintered body and the metal layer and the joining between the aluminum nitride sintered bodies are directly joined not through an adhering agent layer. A plurality of voids having a mean diameter of 0.5-4 μm exist along a joining interface in a direct joining area where plate sintered bodies at the joining interface are directly faced to each other looking from the side sectional plane passing the center of the joined body. A part not joined is formed by the voids and the rate of the part not joined at the side sectional plane is within the range of 0.1-0.5% on the average. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an aluminum nitride bonded body useful as a plate heater or an electrostatic chuck for mounting and processing a semiconductor wafer in a semiconductor manufacturing apparatus. Specifically, it is a plate-like joined body made of an aluminum nitride sintered body joined through a metal layer, and when used as the above-mentioned application, the semiconductor wafer can be processed uniformly and is durable. Is a good bonded structure.

  In a semiconductor manufacturing apparatus for performing film deposition or etching treatment on a semiconductor wafer such as a silicon wafer, a ceramic plate-like sintered body in which a metal layer acting as a heater or an electrode is embedded as a stage for mounting the semiconductor wafer Is used. For example, a heater embedded with a metal layer is used as a plate heater, and a heater embedded with an electrode is used as an electrostatic chuck. In an electrostatic chuck, a metal layer that functions as a heater may be embedded together with an electrode.

  In recent years, an aluminum nitride sintered body having a good thermal conductivity has been used as a ceramic used in the above applications.

  On the other hand, higher precision is required due to higher integration due to technological innovation in recent years, and the diameter of the semiconductor wafer to be processed is also increased. It has become necessary to produce a uniform thin film with high accuracy, and in the etching process, various thin films formed on a semiconductor wafer must be uniformly etched over a large area.

  Under such circumstances, the plate-like sintered body of aluminum nitride embedded with the metal layer used as the plate heater or electrostatic chuck has a uniform thickness from the contact surface with the semiconductor wafer. It is necessary to exist in.

  Conventionally, manufacturing of a plate-like sintered body of aluminum nitride in which a metal layer is embedded has a remarkable disconnection or deformation of the metal layer due to a dimensional change when the metal layer is embedded and sintered in advance, so it is once plate-shaped or sheet-shaped. It was common to obtain a plate-like joined body made of an aluminum nitride sintered body in which a metal layer was embedded by manufacturing a sintered body of the above and then joining these sintered bodies through a metal layer. .

  For example, a method has been implemented in which a metal layer is interposed between plate-like objects of an aluminum nitride sintered body and bonded with an adhesive. However, the conventional adhesive has a problem that a high temperature is required for joining the sintered bodies, and the sintered body is deformed by the heat, and accordingly, the metal layer is warped.

  Then, the method of improving a curvature by using the adhesive agent which improved the composition and lowered | hung the adhesive temperature as this adhesive agent is proposed (refer patent document 1).

  Although the warpage of the obtained bonded body can be improved to some extent by the above method, there is room for improvement. In addition, since the adhesive layer and the aluminum nitride sintered body joined by the adhesive layer are made of different materials, the metal layer partially exists and the aluminum nitride sintered bodies are joined by the adhesive layer. If so, there may be a phenomenon in which the strength of the bonded portion decreases with time due to the thermal history.

JP 2000-252045 A

  Accordingly, an object of the present invention is to provide a plate-like joined body made of an aluminum nitride sintered body joined partially through a metal layer, without using an adhesive, and with a very low warpage of the metal layer. The object is to obtain a suppressed bonded body.

  The inventors of the present invention have made extensive studies to solve the above problems. As a result, the aluminum nitride sintered body with sufficient strength can be obtained without applying an adhesive layer by heating the joint surface of the aluminum nitride sintered body under a specific temperature control while applying a specific pressure. Development of an unprecedented aluminum nitride sintered body that can be bonded to each other and the metal layer and aluminum nitride sintered body, and the warpage of the underlying metal layer is extremely low succeeded in. Furthermore, as a result of analyzing the joined body obtained by the above method, it was found that a non-joint portion having a fine size derived from the method remains characteristically at the joining interface of the aluminum nitride sintered body. The present invention has been completed.

  That is, the present invention is a plate-like joined body of an aluminum nitride sintered body in which a metal layer is interposed on a part of the joining surface, and the aluminum nitride sintered body, the metal layer, and the aluminum nitride sintered body are Directly joined without an adhesive layer, and when viewed in a side cross section passing through the center of the joined body, a direct joining region where the sintered plates directly face each other at the joining interface has a bonding interface. A plurality of pores having an average size of 0.5 to 4 μm are present, and non-joining portions are formed by the pores, and the non-joining rate in the side cross section is 0.1 to 0 on average. An aluminum nitride joined body (hereinafter also referred to as an AlN plate-like joined body) characterized by being in the range of 0.5%.

Moreover, this invention also provides the said manufacturing method for reducing the curvature of the joined body obtained. That is, in the present invention, two aluminum nitride sintered bodies having a sintering aid content of 1% by weight or less are partially present, and a metal layer having a thickness of 20 μm or less is partially present on the surface of one aluminum nitride sintered body. In this state, the other aluminum nitride sintered body is laminated through the metal layer and heated at a temperature of 1650 to 1700 ° C. for 0.5 to 4 hours while being pressed at a pressure of 5 to 100 kg / cm ^2. Then, the present invention also provides a method for producing an aluminum nitride joined body having a metal layer characterized by heating at a temperature exceeding 1700 ° C. and not exceeding 1800 ° C. for 2 to 8 hours.

  The AlN plate-like bonded body of the present invention has a characteristic bonding interface structure based on the specific bonding method described above, so that the warpage of the metal layer is suppressed to a small level. A uniform electric field can be formed at any location on the metal layer without depending on the position on the surface, such as when an electric field is formed on a dielectric.

  Moreover, since it has joined without going through an adhesive bond layer, it is durable against heat history, and a more reliable operation can be expected.

  Therefore, the AlN plate-like joined body of the present invention is extremely effectively used as an electrostatic chuck, a plate heater or the like used in a semiconductor manufacturing apparatus.

(AlN plate assembly)
Hereinafter, the present invention will be described in detail with reference to the drawings. However, the embodiments of the present invention are not limited to those shown in the drawings.

  FIG. 1 is a partially broken perspective view showing a typical embodiment of the AlN plate-like joined body of the present invention. FIG. 2 is a conceptual diagram showing a method for measuring the warpage of the metal layer in the AlN plate-like assembly. Furthermore, FIG. 3 is a conceptual diagram showing a state of a bonding interface including pores in the AlN plate-like bonded body.

  The AlN plate-like joined body of the present invention is a plate-like joined body in which the aluminum nitride sintered bodies 1-a and 1-b are directly joined with the metal layer 2 interposed therebetween.

  As the above-mentioned aluminum nitride sintered body, a known aluminum nitride powder is used without particular limitation, which is obtained by molding and firing by a known method. Among them, it is preferable to use a sintered body having an oxygen concentration in the sintered body of 1% or less and a sintering aid of 0.5% or less.

  In the present invention, the metal layer 2 forms a circuit pattern of electrodes and heaters in the use of the heater plate and electrostatic chuck, and simply exists in a solid pattern as shown in FIG. In some cases, it may exist in a linear pattern.

  The material constituting the metal layer is typically a metal such as tungsten, molybdenum, platinum, titanium, or copper.

  The proportion of the metal layer generally suffices if it is a part of the joint surface. In general, the metal layer is likely to warp in the range of 50 to 90%, preferably 60 to 80%, relative to the joint surface. The present invention is more effective in an AlN plate-like joined body having a metal layer in such a range. The thickness of the metal layer is preferably 20 μm or less, particularly preferably 1 to 15 μm.

  Further, the metal layer is generally provided so as to be a central portion of the joined body.

  Although not shown, the sintered body plate 1-a or 1-b is formed with a through hole so that a conductive paste or the like is filled in the through hole so that the metal layer 2 can be energized. It has a simple structure.

  On the other hand, the thicknesses of the aluminum nitride sintered bodies 1-a and 1-b before joining are appropriately determined so that an AlN plate-like joined body having a desired thickness can be obtained after joining. For example, each sintered body may have the same thickness or may have a different thickness. In general, it is preferable to determine the thickness of the surface on which the semiconductor wafer is placed so as to be thinner than the other.

  The total thickness of the AlN plate-like joined body is somewhat different depending on the application, but is generally 1 to 100 mm.

  The AlN plate-like joined body of the present invention is formed by directly joining the aluminum nitride sintered body with a metal layer interposed. The term “directly” means that bonding is performed without using an adhesive layer that has been used in the past. When the metal layer is partially present, the sintered aluminum nitride bodies and the sintered aluminum nitride are used. A state in which the bonded body and the metal layer are directly joined without an adhesive layer interposed therebetween.

Bonding strength by the direct bonding, the shear strength as measured by die shear tester, between the aluminum nitride sintered body 9.5~11.0kg / mm ^2, in particular, in 10.0~11.0kg / mm ² There, an aluminum nitride sintered body - with metal layers, 2.5~4.0kg / mm ^2, in particular, a 3.0~4.0kg / mm ^2.

  In the AlN plate-like joined body of the present invention, since the joined body is configured with the above-described high joint strength, the interface with the dissimilar material is less than the case where an adhesive layer is interposed, and the heat repeated history is reduced. It has the effect that the strength reduction is extremely small.

  Incidentally, in the AlN plate-like joined body of the present invention, the shear strength of the joint surface between the metal layer and the aluminum nitride sintered body after repeating the thermal history by raising and lowering the temperature from 25 ° C. to 350 ° C. 100 times is as described above. It exhibits extremely good heat resistance history characteristics of 90% or more with respect to the shear strength before heat history.

  The greatest feature of the AlN plate-like joined body of the present invention is that the warp of the metal layer is remarkably small in the joined body. That is, the AlN plate-like joined body of the present invention is characterized in that the joined body itself is not provided with an adhesive layer, but the warpage of the metal layer embedded in the joined body is also extremely small.

  In the present specification, as shown in FIG. 2, the warp (W) of the metal layer is a metal layer farthest from a line (dotted line) connecting the end points of the metal layer at a cutting plane perpendicular to the metal layer. The distance (R; μm) is measured, and this is a value obtained by the following formula using the length (T; mm) between the end points.

W (μm / 10 mm) = R / T × 10
In the AlN plate-like joined body of the present invention, the position of the metal layer is not particularly limited, but from one surface of the plate-like joined body, the total thickness of the plate-like joined body is 0.1. It is preferable to determine that it exists at a position having a depth of ˜50%.

  The AlN plate-like joined body according to the present invention exhibits excellent physical properties such that the warpage is 5 to 25 μm / 10 mm, particularly 10 to 20 μm / 10 mm.

  Such an excellent low warpage characteristic is a value that cannot be achieved by an AlN plate-like joined body using a conventional adhesive, and is a value that is achieved for the first time by a special manufacturing technique described later in the direct joining.

  The joined body of the present invention in which the warpage of the metal layer is suppressed can be achieved by a manufacturing method described in detail later. The structure of the present invention can be achieved by reducing the warpage by such a manufacturing method. When the body is seen in a side cross section passing through the center of the bonded body, the length L is averaged along the bonded interface in the directly bonded region where the sintered body plates directly face each other at the bonded interface. A plurality of holes having a size of 0.5 to 4 μm are present, and a non-joint portion is formed by the holes. In addition, it is preferable that the said hole does not exist that length L is 5 micrometers or more.

  Another feature is that the non-bonding rate in the side cross section is on average 0.1 to 0.5%, preferably 0.2 to 0.4%.

  That is, the method for manufacturing a bonded body according to the present invention performs a process of partially co-sintering and fixing (temporarily fixing) the bonding surface in a low temperature region where the thermal expansion of the aluminum nitride sintered body is relatively small, The co-sintering proceeds at a high temperature within a range that maintains the fixed state to form a joint, and the non-joint part finally remains as fine pores. Moreover, since the holes are formed by the progress of joining from the surroundings, the holes are relatively close to a sphere.

  In contrast, when the aluminum nitride sintered bodies are joined to each other without carrying out the joining method of the present invention, for example, when joining is performed near the sintering temperature of the aluminum nitride sintered body, the progress of joining The non-bonded part remains, but the bonding interface has a degree of freedom at the time of bonding, and fixing of the bonding interface occurs at a relatively high temperature during the process of cooling, so that the bonded body after cooling can easily be distorted, Warping occurs. In addition, since the bonding interface has a degree of freedom at the time of bonding, vacancies are easily moved and deformed, and large vacancies are unevenly distributed or vacant in a non-joined portion in a shape crushed in the plane direction There are many.

A preferred structure is that the shape of the holes is close to a sphere. That is, as a preferable aspect of the aluminum nitride joined body of the present invention, the pores constituting the non-joined portion have a length perpendicular to the interface (L _Y ) and a length parallel to the interface (L _X ). A mode in which the ratio (L _X / L _Y ) is 0.8 to 2, preferably 1.0 to 1.5 is exemplified.

Incidentally, the non-bonding rate, and will be described in the unbonded portion _(L X _/ L _Y) in detail, it is determined by the following method.

1) Non-joining rate In the present invention, the non-joining rate, which is the proportion of fine pores present in the non-joining portion at the joining interface, is calculated by the following formula (1) for the side cross section. .

Non-bonding rate Q = (X / Y) × 100 (1)
(In the formula, X is the length in the bonding interface direction of the non-joined portion represented by the total value of the length L of the holes existing in the direct bonding region, and Y is the direct length where the holes exist. The length of the binding area.)
Specifically, a plurality of cut surfaces are taken from the center of the joined body to the outside, and the interface between the aluminum nitrides on the cut surfaces is continuously photographed at a magnification of 600 times using a scanning electron microscope (SEM). The length Ln (n = 1 to N; N is the total number of vacancies existing at the interface, as shown in FIG. ) And the non-bonding rate is obtained using the following formula (1).

2) (L _X / L _Y ) of non-joined part
In the cut surface, the length in the vertical direction (L _Y ) and the length in the direction parallel to the interface (L _X ) are measured for each hole in the interface between the aluminum nitride sintered bodies, The average of the ratio (L _X / L _Y ) is obtained.

(Method for producing AlN plate-like assembly)
Although the manufacturing method of the AlN plate-like joined body of the present invention is not particularly limited, the following method can be mentioned as a representative method.

That is, according to the present invention, two aluminum nitride sintered bodies having a sintering aid content of 1% by weight or less are present, and a metal layer having a thickness of 20 μm or less is present on the surface of one aluminum nitride sintered body. In this state, the other aluminum nitride sintered body is laminated through the metal layer and heated at a temperature of 1650 to 1700 ° C. for 0.5 to 4 hours while being pressed at a pressure of 5 to 100 kg / cm ² . Next, a method for producing an aluminum nitride joined body having a metal layer, characterized by heating at a temperature exceeding 1700 ° C. and not exceeding 1800 ° C. for 2 to 8 hours is also provided.

  In the above production method of the present invention, the aluminum nitride sintered body for constituting the AlN plate-like joined body has a content of the sintering aid of 1% by weight or less, preferably 0.5% by weight or less. However, it is preferable in order to reliably perform the bonding without interposing an adhesive by the treatment at the temperature described later. Further, as described above, the aluminum nitride sintered bodies to be joined may have the same thickness or may be different.

  In the present invention, the AlN sintered body plate to be heat-bonded can be produced by a method known per se. For example, a baking powder made of AlN powder is mixed with an organic binder to form a granulated powder or a paste. It can be produced by preparing a molding material, molding the molding material into a sheet, removing the obtained green sheet, and firing.

  If necessary, an oxide of an alkaline earth metal such as Mg, Ca or Sr, an oxide of a rare earth element such as Y, or the like can be added to the firing powder as a sintering aid. The amount of the sintering aid added is usually 1% by weight or less, particularly 0.5% by weight or less.

  The organic binder is not limited to this, but generally polyvinyl butyral, polymethyl methacrylate, carboxymethyl cellulose, polyvinyl pyrrolidone, polyethylene glycol, polyethylene oxide, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, Polystyrene, polyacrylic acid, etc. are used. Such an organic binder is generally used in an amount of 0.1 to 30 parts by weight per 100 parts by weight of the above-mentioned baking powder, although it varies depending on the type.

  In preparing the molding material, if necessary, a dispersant such as a long-chain hydrocarbon ether, a solvent such as toluene and ethanol, and a plasticizer such as phthalic acid can be used in appropriate amounts.

  Production of a molding sheet (green sheet) using the molding material is performed by a known molding method such as an extrusion molding method, a doctor blade method, or a press molding method.

  Debinding is generally performed by heating the green sheet to about 300 to 900 ° C. in air, and firing is performed on the green sheet after debinding in an inert atmosphere (for example, in a nitrogen atmosphere), 1700 to 1900. This is done by heating to a temperature of ° C. The firing time may normally be a time such that the relative density by the Archimedes method is 98% or more.

  The surface of the sintered body obtained as described above is subjected to grinding so that the average surface roughness Ra is 0.1 to 0.8 μm, preferably 0.2 to 0.6 μm. This is preferable in order to strengthen the adhesion between the metal layers described later and the aluminum nitride sintered bodies.

  In the present invention, 3 is formed on the sintered body after processing, and the surface on which the metal layer is formed and the aluminum nitride sintered body 2 are adhered to each other to form a joined body. The conditions for forming the joined body are as follows.

The aluminum nitride sintered body 1-a and the aluminum nitride sintered body 1-b are 1650-1700 ° C. while being pressed at a pressure of 5-100 kg / mm ² with the metal layer 3 partially overlapped. For 0.5 to 4 hours, and then at 1750 to 1800 ° C. for 2 to 8 hours, a joined body having a metal layer on the inner surface can be formed.

  In the above-described method, the formation of the metal layer should be preliminarily present on the surface of one of the aluminum nitride sintered bodies to be bonded, so that the arrangement of the metal layer can be determined with certainty. Is preferable because it can be protected. Examples of specific methods include a method of applying a metal paste and sintering it, a mode of forming a metal layer on the surface of an aluminum nitride sintered body by a physical vapor deposition method such as an ion plating method, and the like. Can be mentioned.

  As described above, the thickness of the metal layer is preferably 20 μm or less, and particularly preferably 1 to 15 μm, in order to reliably bond the aluminum nitride sintered bodies at portions where the metal layer does not exist.

  In the method for producing an AlN plate-like joined body according to the present invention, the sintered aluminum nitride formed with the metal layer and the other sintered aluminum nitride are laminated with the metal layer interposed therebetween, and 2 under pressure. Heat in stages.

First, in the first stage, the pressure is 1650 to 1700 ° C., preferably 1650 to 1680 ° C. for 0.5 to 4 hours while being pressed at a pressure of 5 to 100 kg / cm ² , preferably 10 to 30 kg / cm ^2. The treatment is preferably carried out by heating for 1 to 2 hours.

  In the second stage, an AlN plate-like joined body that is heated at a temperature exceeding 1700 ° C. and not exceeding 1800 ° C., preferably 1750 to 1790 ° C. for 2 to 8 hours, preferably 4 to 6 hours. Preferred for obtaining.

That is, in the above method, when the first stage heating temperature is increased to the second stage temperature at a time, the warping of the bonded substrate is likely to occur. In the joined body obtained under such conditions, the length of the non-joined portion is increased, and the value of L _X / L _Y is also increased, resulting in an elongated space. This is presumably due to insufficient fixation of the bonding interface during bonding.

  Further, when the first stage heating temperature is lower than 1650 ° C., bonding becomes difficult. The joined body that has been treated under the above conditions has a lack of joined parts and a large amount of the non-joined parts remaining, so that the proportion of non-joined parts increases.

  Further, when the first stage heating time is shorter than the above range, the temporary fixing effect is insufficient, and the problem of warping occurs as in the case where the first stage heating temperature is raised to the second stage temperature. .

  Further, when the length is longer than the above range, the diffusion of the metal layer metal to the substrate proceeds, and there arises a problem that the distribution of the metal layer in the substrate becomes non-uniform.

  On the other hand, when the heating temperature at the second stage is higher than the above range, the diffusion of the metal layer to the aluminum nitride substrate proceeds and the metal layer distribution becomes non-uniform. Moreover, when heating temperature is lower than 1700 degreeC, the problem that sufficient joint strength is not acquired arises. In the joined body obtained under such conditions, the joint portion does not grow sufficiently, and a large amount of the non-joined portion remains, so that the proportion of the non-joined portion increases.

  Further, when the heating time at the second stage is shorter than the above range, there arises a problem that the bonding strength is lowered due to insufficient bonding, and when it is longer than the above range, there is a problem that warpage becomes large.

  Furthermore, when the pressure acting on the joining surface of the aluminum nitride sintered body through the first and second heating steps is smaller than the above range, the joining force is reduced and a large amount of the non-joined portion remains. The proportion of non-joined parts increases. On the other hand, when it is too strong, the sintered body is damaged, and the yield is lowered.

  With respect to the mechanism by which the target AlN plate-like joined body can be obtained by the above-described method of the present invention without using an adhesive and suppressing the occurrence of warpage, the inventors have estimated as follows. is doing.

  That is, sintered particles that are in contact with each other at a relatively low temperature are bonded by heating at the first stage, and the aluminum nitride substrate to be bonded is fixed (temporarily fixed), while maintaining such a positional relationship, It is presumed that a joined part with less warpage can be formed by the joining part proceeding at the second stage and causing stronger joining. In addition, since no adhesive is used, it is presumed that warpage hardly occurs even when significant grain boundary movement does not occur.

  Hereinafter, the effects of the present invention will be described in more detail with reference to Examples and Comparative Examples. Needless to say, the present invention is not limited to the examples described below.

  Various measurements in Examples and Comparative Examples were performed by the following methods.

(1) Non-bonding rate From the center of the bonded body to the outside, four cut surfaces are taken at intervals of 90 degrees, and the interface between the aluminum nitrides of the cut surface is taken using a scanning electron microscope (SEM). Pictures were taken continuously at a magnification of 600 times. Thereafter, based on the above photograph, the length Ln (n = 1 to N; N is the total number of vacancies existing at the interface) of the portion not joined by the vacancies present at the interface shown in FIG. The non-bonding rate was determined for each cut surface using the following formula (1), and the average value was shown.

(2) (L _X / L _Y ) of non-joined part
At each of the cut surfaces, the length (L _Y ) in the direction perpendicular to the interface of the non-joint portion and the length in the direction parallel to the interface (L _X ) at the interface between the aluminum nitride sintered bodies are measured, and the ratio _(L X / _{L Y)} look for the holes, showed the average value.

(3) Measurement of warpage (W) of metal layer For each cross section obtained by dividing the AlN plate-like joined body into two parts, as shown in FIG. 2, the end points of the metal layer are connected at a cut surface perpendicular to the metal layer. The distance (R; μm) of the metal layer farthest from the line (dashed line) was measured, and this was calculated by the following formula using the length (T; mm) between the end points, and the largest value was displayed as the warp of the metal layer. .

W (μm / 10 mm) = R / T × 10
(4) Heat-resistant hysteresis characteristics An AlN plate-like joined body is put in a thermal shock chamber (manufactured by ESPEC Corporation, model TSC-103 (W)), heated from 25 ° C. to 350 ° C. in 30 minutes, and then up to 25 ° C. The shear strength at the joint interface of the joined body after 100 times of raising and lowering the temperature to cool in 30 minutes was measured, and the ratio to the shear strength before giving the thermal history was calculated by the following formula and displayed as the heat resistance history characteristics.

Heat-resistant history characteristics (%) = Share strength after thermal history × 100 / Share strength before thermal history Example 1
Cover an area of 5 mm from the outer periphery with an aluminum mask on one side of an aluminum nitride substrate with a diameter of 40 mm and a thickness of 6 mm and without addition of a sintering aid (Tokuyama, SH-50, Y0.02%, Ra0.4) The film was formed in the order of Ti 0.2 micron and W 1 micron by the ion plating method. Next, the aluminum nitride substrate SH-50 on which no film was formed was stacked with the Ti / W film on the inside, fixed with a carbon sample jig, and placed in a hot press furnace. Thereafter, while applying a load of 300 kgf (pressure 23.9 kg / cm ² ), the mixture was held at 1650 ° C. for 2 hours in a nitrogen stream, then heated to 1750 ° C. at a heating rate of 10 ° C./min, and then held for 4 hours. After cooling to room temperature, it was taken out from the furnace to obtain an AlN plate-like joined body.

  Tables 1 and 2 show the production conditions and various characteristics of the AlN plate-like joined body.

The warp W of the metal layer of the obtained AlN plate-like joined body was 12 μm / 10 mm. Then, by measurement of shear strength of the bonding interface is 3.8kgf / mm ² at an interface containing a metal layer, at the interface without the metal layer was 10 kgf / mm ^2. Moreover, the heat-resistant history characteristic was 100%. Next, from the center of the joined body to the outside, four cut surfaces are taken at intervals of 90 degrees, and the interface between the aluminum nitrides on the cut surface is magnified 600 times using a scanning electron microscope (SEM). When the non-bonding rate Q was calculated using the formula (1), it was 0.2% and the average length L of the holes was 1.8 μm. The average length ratio L _X / L _Y was 1.1.

Example 2
On one side of a 326 mm diameter, 10 mm thick sintering additive-free aluminum nitride substrate (Tokuyama Corporation, SH-50, yttria 0.02%, Ra 0.4), Ti 0.2 micron by ion plating method , W1 microns were formed in this order. Next, a region having a radius of 146 mm from the center of the film formation surface was masked, and a Ti / W film having a width of 17 mm from the outer periphery was removed by dipping in a 1: 1 mixture of 5 vol% hydrofluoric acid / 5 vol% nitric acid.

Next, the aluminum nitride substrate SH-50 on which no film was formed was stacked with the Ti / W film on the inside, fixed with a carbon sample jig, and placed in a hot press furnace. Thereafter, while applying a load of 20 tf (pressure 24.0 kg / cm ² ), the mixture was held in a nitrogen stream at 1690 ° C. for 2 hours, then heated to 1790 ° C. at a rate of temperature increase of 3 ° C./min, and then held for 4 hours. After cooling to room temperature, it was taken out from the furnace to obtain an AlN plate-like joined body.

  Tables 1 and 2 show the production conditions and various characteristics of the AlN plate-like joined body.

About the obtained AlN plate-shaped joined body, the curvature W of the metal layer was 17 micrometers / 10mm. Next, when the shear strength of the bonding interface was measured, it was 3.5 kg / mm ² at the interface including the metal layer and 10 kg / mm ² at the interface not including the metal layer. Moreover, the heat-resistant history characteristic was 100%. Next, when the non-bonding rate Q was determined, it was 0.2%, the average of the length L of the holes was 2.4 μm, and the average of the length ratio L _X / L _Y of the holes was 1 .2.

Examples 3-5
An AlN plate-like joined body was obtained in the same manner as in Example 1 except that the same substrate as in Example 1 was used and the joining conditions of holding temperature, holding time, and load were changed.

  Tables 1 and 2 show the production conditions and various characteristics of the AlN plate-like joined body.

Example 6
One side of a 40 mm diameter, 6 mm thick sintering additive-free aluminum nitride substrate (Tokuyama Corporation, SH-50, yttria 0.02%, Ra 0.4), Ti 0.2 micron by ion plating method And W9 microns in order. Next, bonding was performed under the same conditions as in Example 2 to obtain an AlN plate-like bonded body.

About the obtained AlN plate-shaped joined body, the curvature W of the metal layer was 19 micrometers / 10mm. Next, when the shear strength of the bonding interface was measured, it was 3.1 kg / mm ² at the interface including the metal layer, and 10 kg / mm ² at the interface not including the metal layer. Further, the heat resistance history characteristic was 99%. Next, the non-bonding rate Q was determined to be 0.2%, the average length L of the holes was 3.8 μm, and the average length ratio L _X / L _Y of the holes was 1. 2.

Comparative Example 1
Cover an area of 5 mm from the outer periphery with an aluminum mask on one side of an aluminum nitride substrate with a diameter of 40 mm and a thickness of 6 mm and without addition of a sintering aid (Tokuyama, SH-50, Y0.02%, Ra0.4) The film was formed in the order of Ti 0.2 micron and W 1 micron by the ion plating method.

Next, an AlN—Y ₂ O ₃ slurry (100 parts by weight of AlN, 5 parts by weight of Y ₂ O ₃ , 4 parts by weight of an acrylic binder, long chain hydrocarbons) is used as an adhesive on an aluminum nitride substrate SH-50 that has not been formed into a film. After applying 0.5 weight part of an ether-based dispersant, the Ti / W films were stacked so that the Ti / W film was on the inside, fixed with a carbon sample jig, and placed in a hot press furnace.

Thereafter, while applying a load of 300 kgf (pressure 23.9 kg / cm ² ), the mixture was held in a nitrogen stream at 1650 ° C. for 2 hours, then heated to 1750 ° C. at a heating rate of 10 ° C./min, and then held for 4 hours. After cooling to room temperature, it was taken out from the furnace to obtain an AlN plate-like assembly having an adhesive layer.

The obtained AlN plate-like joined body was warped in a bowl shape. After the surface of the AlN plate-like joined body was ground and flattened, the measured warpage of the metal layer was 297 μm / 10 mm. Next, when the shear strength of the bonding interface was measured, it was 2.0 kg / mm ² at the interface including the metal layer, and 6 kg / mm ² at the interface not including the metal layer. Further, the heat resistance history characteristic was 68%. Next, the non-bonding rate Q was calculated to be 21.1%, the average of the length L of the holes was 6.5 μm, and the average of the length ratio L _X / L _Y of the holes was 4. It was 8.

Comparative Example 2
An AlN plate-like bonded body was obtained in the same manner as in Comparative Example 1 except that the holding temperature and holding time were changed using the same substrate as in Example 1.

  Tables 1 and 2 show the production conditions and various characteristics of the AlN plate-like joined body.

Comparative Examples 3-9
An AlN plate-like joined body was obtained in the same manner as in Example 1 except that the same substrate as in Example 1 was used and the joining conditions of holding temperature, holding time, and load were changed.

  Tables 1 and 2 show the production conditions and various characteristics of the AlN plate-like joined body.

The partially broken perspective view which shows the typical aspect of the AlN plate-shaped joined body of this invention Conceptual diagram of measurement of warpage of metal layer in the present invention Conceptual diagram showing the state of the bonding interface including pores in the AlN plate-like assembly

Explanation of symbols

1 Aluminum nitride sintered body 2 Metal layer

Claims (8)

  A plate-like bonded body of an aluminum nitride sintered body in which a metal layer is interposed on a part of a bonding surface, the aluminum nitride sintered body and the metal layer, and the aluminum nitride sintered bodies being interposed with an adhesive layer In the direct bonding region where the sintered plates at the bonding interface are directly facing each other, on the side cross-section passing through the center of the bonded body, the average is along the bonding interface. There are a plurality of holes of 0.5 to 4 μm, and non-bonded portions are formed by the holes, and the non-bonding rate in the side cross section is in the range of 0.1 to 0.5% on average. There is provided an aluminum nitride joined body. Wherein the air holes constituting the non-bonded portion, the ratio of the length of the interface and the vertical direction _{(L Y)} and the interface parallel direction length and _{(L X) (L X /} L Y) is 0.8 to 2 The aluminum nitride joined body according to claim 1.   The aluminum nitride joined body according to claim 1 or 2, wherein the warp in the metal layer is 25 µm / 10 mm or less.   The aluminum nitride joined body according to any one of claims 1 to 3, wherein the total thickness of the plate-like joined body is 1 to 100 mm.   The metal layer is present at a position of a depth of 0.1 to 50% with respect to the total thickness of the plate-like joined body from one surface of the plate-like joined body. Aluminum nitride bonded body.   The shear strength of the joint surface between the metal layer and the aluminum nitride sintered body after repeating the thermal history by raising and lowering the temperature from 25 ° C. to 350 ° C. 100 times or more is 90% or more with respect to the shear strength before the thermal history. The aluminum nitride joined body according to any one of claims 1 to 5. Two aluminum nitride sintered bodies having a sintering aid content of 1% by weight or less, with a metal layer having a thickness of 20 μm or less partially present on the surface of one aluminum nitride sintered body, The other aluminum nitride sintered body is laminated through the metal layer and heated at a temperature of 1650-1700 ° C. for 0.5-4 hours while being pressed at a pressure of 5-100 kg / cm ^2. And a method for producing an aluminum nitride joined body having a metal layer, characterized by heating at a temperature of 1800 ° C. or lower for 2 to 8 hours. The method for producing an aluminum nitride joined body according to claim 7, wherein the aluminum nitride sintered body has an average surface roughness Ra (JIS B 0601) in the range of 0.1 to 0.8 µm.

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