JP3645595B2 - Thin film wiring board - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a thin film wiring board, and more particularly to a thin film wiring board used for an electric circuit board having a high density of circuit wiring, a package for housing semiconductor elements, and the like.
[0002]
[Prior art]
Conventionally, wiring boards in electrical circuit boards, semiconductor element storage packages, and the like have their circuit wiring formed by a thick film forming technique such as the Mo-Mn method.
[0003]
In this Mo-Mn method, an organic solvent or solvent is added to a metal powder composed of a refractory metal such as tungsten (W), molybdenum (Mo), manganese (Mn), etc. to produce or paste the metal paste into a paste form. In this method, a predetermined pattern as circuit wiring is printed and applied to the outer surface of the sintered ceramic body by screen printing, and then fired in a reducing atmosphere to sinter and integrate the refractory metal and the ceramic body.
[0004]
However, when circuit wiring is formed using this Mo-Mn method, circuit wiring is formed by screen-printing a metal paste, so it is difficult to make circuit wiring finer, and circuit wiring has a higher density. It had the disadvantage that it was not possible.
[0005]
Therefore, in order to eliminate the above-mentioned drawbacks, the applicant of the present invention firstly made a thin film wiring substrate formed by using a thin film forming technique capable of miniaturization instead of forming a circuit wiring by a conventional thick film forming technique. Adhesive layer made of tantalum nitride (Ta ₂ N), nickel-chromium alloy (NiCr), etc. on the substrate, nickel-chromium alloy (NiCr), titanium-tungsten alloy (TiW), nickel (Ni), palladium (Pd) An intermediate layer made of gold, etc. and a main conductor layer made of gold (Au) are sequentially laminated by a thin film forming technique such as ion plating, sputtering, vapor deposition, plating, etc., and then these layers are formed by photolithography. A thin-film wiring board formed as a circuit wiring in a predetermined pattern has been proposed (see Japanese Patent Application No. 3-270721).
[0006]
In the thin film wiring board, the adhesive layer functions to firmly bond the circuit wiring to the insulating substrate, and the intermediate layer suppresses mutual diffusion of the adhesive layer and the main conductor layer and firmly fixes the main conductor layer to the adhesive layer. It works to adhere to.
[0007]
Further, according to the thin film wiring substrate, since the adhesive layer has a certain degree of conduction resistance, if a part of the main conductor layer and the intermediate layer in the circuit wiring are removed and only the adhesive layer is formed, The resistor can be easily and integrally connected to the circuit wiring without separately preparing a resistor as an electronic component.
[0008]
[Problems to be solved by the invention]
However, in this thin film wiring board, the adhesive layer of the circuit wiring is formed with a single layer, and the electric resistance value per unit area is constant. Therefore, some main conductor layers and intermediate layers of the circuit wiring are removed. When a plurality of resistors having different electrical resistance values are integrally connected to the circuit wiring by forming a region only of the adhesive layer, the main conductor layer and the intermediate layer of the circuit wiring are connected to the resistor having a large electrical resistance value. Disadvantage that it must be removed over a wide area, resulting in a large area occupied by the resistor in the circuit wiring, and a large number of resistors having different electrical resistance values cannot be electrically connected to the circuit wiring in a compact manner Had.
[0009]
OBJECT OF THE INVENTION
The present invention has been devised in view of the above-described drawbacks, and the object thereof is to make the circuit wiring high density and to electrically connect a large number of resistors having different electrical resistance values to the circuit wiring in a compact and integrated manner. It is to provide a thin film wiring substrate.
[0010]
[Means for Solving the Problems]
In the present invention, a circuit wiring having a three-layer structure in which an adhesive layer, an intermediate layer, and a main conductor layer are sequentially laminated on an insulating substrate by a thin film formation technique is deposited and bonded to a part of the circuit wiring. A thin film wiring board formed by connecting resistors using layers, wherein the insulating substrate is at least one of an aluminum oxide sintered body, a mullite sintered body, an aluminum nitride sintered body, and a glass ceramic sintered body. The adhesive layer is formed of two layers having different conduction resistances in which a nickel-chromium alloy layer and a tantalum nitride layer are sequentially laminated on the insulating substrate, and the resistor is formed of the tantalum nitride layer. A silicon oxide film is deposited on the surface via a tantalum oxide film.
[0011]
[Action]
According to the thin film wiring board of the present invention, since the adhesive layer of the circuit wiring has a multilayer structure and the conduction resistance of each layer is made different, a part of the main conductor layer and the intermediate layer of the circuit wiring are removed, and only the adhesive layer is formed. When a plurality of resistors having different electric resistance values are integrally connected to the circuit wiring by forming a region, the area occupied by the circuit in the circuit wiring is narrow depending on which layer of the multilayer adhesive layer is exposed. As a result, the electric resistance value can be set to an arbitrary value, and as a result, a large number of resistors having different electric resistance values can be electrically connected to the circuit wiring in a compact and integrated manner.
[0012]
Further, according to the thin film wiring board of the present invention, since the circuit wiring is formed by a thin film forming technique, the circuit wiring can be miniaturized and the circuit wiring can be densified.
[0013]
【Example】
Next, the thin film wiring board of the present invention will be described in detail with reference to the accompanying drawings.
1 and 2 are sectional views showing an embodiment of the thin film wiring board of the present invention, wherein 1 is an insulating substrate and 2 is a circuit wiring.
[0014]
The insulating substrate 1 acts as a support member for supporting the circuit wiring 2, and includes an aluminum oxide sintered body, a mullite sintered body, a silicon carbide sintered body, an aluminum nitride sintered body, a glass ceramic sintered body, etc. It is made of an electrically insulating material.
[0015]
In the case where the insulating substrate 1 is made of, for example, an aluminum oxide sintered body, a suitable organic solvent and solvent are added to and mixed with raw material powders such as alumina, magnesia, calcia, and silica to form a slurry, and this is formed by a doctor blade method. A ceramic green sheet (ceramic green sheet) is formed by adopting a calender roll method or the like, and then, the ceramic green sheet is appropriately punched into a predetermined shape and fired at a high temperature (about 1600 ° C). It is manufactured by doing.
[0016]
A circuit wiring 2 is deposited on the upper surface of the insulating substrate 1 by a thin film forming technique, and the circuit wiring 2 has a three-layer structure of an adhesive layer 3, an intermediate layer 4, and a main conductor layer 5. Yes.
[0017]
The adhesive layer 3 constituting the circuit wiring 2 works to increase the adhesive strength between the insulating substrate 1 and the circuit wiring 2 and is made of tantalum nitride (Ta2N) or nickel-chromium alloy (NiCr). The film is deposited on the insulating substrate 1 by employing a thin film forming technique such as a ting method.
[0018]
Further, an intermediate layer 4 is deposited on the upper surface of the adhesive layer 3, and the intermediate layer 4 improves the adhesion between the adhesive layer 3 and the main conductor layer 5, and the adhesive layer 3 and the main conductor layer 5. It works to prevent mutual diffusion.
[0019]
The intermediate layer 4 is made of nickel-chromium alloy (NiCr), titanium-tungsten alloy (TiW), nickel (Ni), palladium (Pd), titanium (Ti), etc., such as vapor deposition method, ion plating method, sputtering method, etc. The thin film forming technique is applied to the upper surface of the adhesive layer 3.
[0020]
If the thickness of the intermediate layer 4 is less than 500 angstroms, the adhesion between the adhesive layer 3 and the main conductor layer 5 is lowered and the mutual diffusion between the adhesive layer 3 and the main conductor layer 5 is effectively prevented. When the thickness exceeds 10000 angstroms, the adhesive strength between the adhesive layer 3 and the intermediate layer 4 tends to decrease due to internal stress when the intermediate layer 4 is deposited by the thin film formation technique. The range of angstroms is good, preferably 800 to 5000 angstroms, and most preferably 1000 to 3000 angstroms.
[0021]
A main conductor layer 5 is deposited on the upper surface of the intermediate layer 4 by a thin film forming technique such as a vapor deposition method, an ion plating method, a sputtering method, or a plating method, and the main conductor layer 5 is a passage through which electricity mainly passes. Act as.
[0022]
The main conductor layer 5 is made of gold (Au) or copper (Cu) having a very low conduction resistance, and if the thickness is less than 1 μm, the conduction resistance of the circuit wiring 2 becomes high and is not suitable as a thin film wiring board. Therefore, the thickness is preferably 1 μm or more, more preferably 4 μm or more.
[0023]
The circuit wiring 2 formed on the insulating substrate 1 can be miniaturized because each of the adhesive layer 3, the intermediate layer 4 and the main conductor layer 5 constituting the circuit wiring 2 is formed by a thin film forming technique. Thus, the circuit wiring 2 can be densified.
[0024]
Further, the circuit wiring 2 formed on the insulating substrate 1 by the thin film formation technique has a region A in which the intermediate metal layer 4 and the main conductor layer 5 are removed and only the adhesive layer 3 is formed. The adhesive layer 3 can act as a resistor 6 as an electronic component due to the high electrical resistance value of the tantalum nitride, nickel / chromium alloy, or the like constituting the adhesive layer 3. In this case, the resistor 6 can be easily and integrally connected to the circuit wiring 2 simply by removing the intermediate layer 4 and the main conductor layer 5 constituting the circuit wiring 2. There is no need to separately prepare and bond a resistor as an electronic component to the circuit wiring 2.
[0025]
Further, the resistor 6 formed by removing a part of the intermediate layer 4 and the main conductor layer 5 of the circuit wiring 2 has a multi-layer structure if the adhesive layer 3 is formed in advance in a multi-layer structure with materials having different conduction resistances. Depending on which layer of the adhesive layer 3 is exposed, the electrical resistance value of the resistor 6 can be set to an arbitrary value with the area occupied by the circuit wiring 2 being narrow, and the electrical resistance value of the circuit wiring 2 is different. A large number of resistors 6 can be electrically connected together in a compact manner.
[0026]
For example, as shown in FIG. 2, the adhesive layer 3 having the multilayer structure is a layer 3a of a nickel-chromium alloy (conducting resistance 100 Ω / SQ) having a thickness of 0.04 μm from the insulating substrate 1 side, and a tantalum nitride having a thickness of 0.15 μm. Layer 3b (conduction resistance 33 Ω / SQ) and 0.03 μm thick chromium (conduction resistance 8 Ω / SQ) layer 3c are sequentially formed by thin film formation techniques such as vapor deposition, ion plating, sputtering, and plating. When the uppermost chromium alloy layer 3c of the adhesive layer 3 is exposed, the electrical resistance value of the resistor 6 is about 5 Ω, and the tantalum nitride layer 3b of the adhesive layer 3 is exposed. Thus, the electrical resistance value of the resistor 6 can be about 50Ω, and the nickel / chromium layer 3a of the adhesive layer 3 can be exposed to make the electrical resistance value of the resistor 6 about 200Ω.
[0027]
Note that if the resistor 6 integrally connected to the circuit wiring 2 is covered with a silicon oxide film on its surface, moisture or the like contained in the atmosphere comes into contact with the resistor 6 and the electrical resistance of the resistor 6 is reduced. It is possible to effectively prevent the resistance value from changing, and to keep the electrical resistance value of the resistor 6 constant at all times. Therefore, it is preferable that the resistor 6 integrally connected to the circuit wiring 2 has a silicon oxide film deposited on the surface thereof.
[0028]
When the resistor 6 is covered with a silicon oxide film, the silicon oxide film is made of an oxide and itself has poor adhesion to tantalum nitride. Therefore, the resistor 6 is exposed by exposing the tantalum nitride layer of the adhesive layer 3. When a tantalum oxide film is formed, a tantalum oxide film is interposed between the resistor 6 and the silicon oxide film so that they are firmly adhered to each other.
[0029]
Further, the silicon oxide film is deposited on the exposed surface of the resistor 6 to a thickness of 1.0 to 3.0 μm by employing a thin film forming technique such as sputtering, and the tantalum oxide film has a tantalum nitride layer exposed. The resistor 6 is heated to a predetermined temperature and its surface is thinly oxidized to form the resistor 6 between the resistor 6 and the silicon oxide film.
[0030]
Thus, according to the thin film wiring board of the present invention, when electronic components such as semiconductor elements and capacitors are joined to the circuit wiring 2 on the insulating substrate 1 via solder, each electronic component is electrically connected via the circuit wiring 2. Will be.
[0031]
The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.
[0032]
【The invention's effect】
According to the thin film wiring board of the present invention, since the adhesive layer of the circuit wiring has a multilayer structure and the conduction resistance of each layer is made different, a part of the main conductor layer and the intermediate layer of the circuit wiring are removed, and only the adhesive layer is formed. When a plurality of resistors having different electric resistance values are integrally connected to the circuit wiring by forming a region, the area occupied by the circuit in the circuit wiring is narrow depending on which layer of the multilayer adhesive layer is exposed. As a result, the electric resistance value can be set to an arbitrary value, and as a result, a large number of resistors having different electric resistance values can be electrically connected to the circuit wiring in a compact and integrated manner.
[0033]
Further, according to the thin film wiring board of the present invention, since the circuit wiring is formed by a thin film forming technique, the circuit wiring can be miniaturized and the circuit wiring can be densified.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a thin film wiring board of the present invention.
FIG. 2 is an enlarged cross-sectional view of a main part of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Insulating substrate 2 ... Circuit wiring 3 ... Adhesive layer 4 ... Intermediate layer 5 ... Main conductor layer 6 ... Resistor

Claims (1)

A circuit wiring having a three-layer structure in which an adhesive layer, an intermediate layer and a main conductor layer are sequentially laminated on an insulating substrate by a thin film formation technique is deposited and a circuit wiring adhesive layer is used as a part of the circuit wiring. A thin film wiring board formed by connecting resistors, wherein the insulating substrate is made of at least one of an aluminum oxide sintered body, a mullite sintered body, an aluminum nitride sintered body, and a glass ceramic sintered body. The adhesive layer is formed of two layers having different conduction resistances in which a nickel-chromium alloy layer and a tantalum nitride layer are sequentially laminated on the insulating substrate, and the resistor is formed on the surface of the tantalum nitride layer. A thin film wiring board comprising a silicon oxide film deposited through a film.

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