JPS60254639A - Electrode film and manufacture thereof - Google Patents

Abstract

PURPOSE:To form electrode films without damaging the quality of adhesion surfaces by a method wherein an electrode film produced by metal lamination is adhered on a nichrome layer as the lower layer by adhesion through magnetron- sputtering. CONSTITUTION:A plurality of targets 12 incorporated together with the anode and a magnet for impressing the orthogonal electromagnetic field are arranged by dispersion in opposition to the outer cylindrical plane of a substrate holder 11. A nichrome film adhred to the target-opposed surface of a substrate 14 by using the nichrome target 12 comes nearly into the same composition as that of the target 12 and is adhred at low temperature. This reduces the thermal impact received by the substrate 14 and the previously adhered layer.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to an electrode film formed for bonding lead terminals, mounting elements, etc. of a thin film hybrid integrated circuit or the like.

(b) Background of the Technology In a thin film hybrid integrated circuit formed by forming and mounting circuit elements, electrodes formed on a circuit board for bonding one end of an external lead terminal, for example, are generally made of nichrome (
The base layer is made of (NiCr) and a gold (Au) layer is deposited thereon. In such electrodes, the Au layer, which has excellent characteristics as a bonded electrode, has no adhesion to the surface of the alumina substrate and the tantalum (Ta) layer deposited on the surface, or has insufficient adhesive strength. In view of this, a NiCr layer is interposed as the underlying layer.

On the other hand, with regard to thin film hybrid integrated circuits, in response to the demand for smaller size and higher density of devices in which the circuits are mounted, miniaturization of patterns is progressing in order to achieve higher integration.

(C) Prior art and problems Figure 1 shows an enlarged schematic cross-section of an electrode portion formed on a thin film hybrid integrated circuit, where 1 is an alumina substrate, 2 is a Ta layer, and 3 is an electrode. The electrode layer 3 has a nichrome NiCr layer 4 as a base layer, and an Au layer 5 is formed thereon to constitute a bonding electrode film.

In this electrode layer 3, a NiCr film and an A layer are deposited to pattern the NiCr layer 4 and Au layer 5.
U films have traditionally been deposited by vacuum evaporation.

However, in the vacuum evaporation method, variations in the deposition particles and film thickness distribution have been an obstacle to the formation of fine patterns in highly integrated hybrid integrated circuits due to the generation of deposition particles and film thickness distribution. - Therefore, a sputtering method can be considered as a means for forming the film, but in order to form the required film using conventional sputtering, that is, a sputtering apparatus called a DC two-pole sputtering method or an RF (radio frequency) sputtering method, it is difficult to Since the sputtering temperature is heated to several hundred degrees Celsius, the substrate itself and the already formed layers (films) of the substrate must have resistance to the sputtering temperature.

(d) Purpose of the Invention The purpose of the present invention is to provide an electrode film and a method for manufacturing the same that eliminate the above-mentioned problems and have improved performance by using a magnetron sputtering device having characteristics such as low temperature and high speed. It is.

(e) Structure of the Invention The above object is to provide an electrode characterized in that an electrode film having at least a nichrome (NiCr) layer as a lower layer and a gold (Au) layer laminated thereon is deposited by magnetron sputtering. This is achieved by a membrane and its manufacturing method.

(f) Examples of the invention The present invention will be explained in detail below using the drawings.

Figure 2 shows a magnetron sputtering device, which uses orthogonal electromagnetic fields to confine plasma moving according to Lorentz's equation in a local space near the target (cathode), and electrons moving cycloidally on the target collide with gas molecules, resulting in density 1 is a schematic diagram for explaining the outline of a sputtering apparatus characterized in that high plasma is generated, damage caused by electrons colliding with a sputtering substrate is eliminated, and a high sputtering rate can be obtained.

In FIG. 2, 11 is a cylindrical substrate holder that can be rotated or reversed, 12 is a target made of the same material as the sputtered film material, and 13 is rotatable to appropriately partition the opposing space between the holder 11 and the target eye 2. The shutter 14 is a plurality of sputtered film-coated substrates attached to the outer cylindrical surface of the holder 11. In general, a plurality of targets 12 (for example, three targets) installed together with an anode electrode (not shown), a magnet for applying an orthogonal electromagnetic field (not shown), etc. It is arranged.

A target 12 made of a sputtered film, for example, nichrome (NiCr), deposited by such an apparatus is used to form a substrate 14.
The NiCr film deposited on the target facing surface has almost the same composition as the target 12, and is deposited at a lower temperature (for example, 80° C.) than in the conventional device.

Therefore, the thermal shock to which the substrate 14 and already deposited layers (films) are subjected can be reduced by conventional DC bipolar spunter method or RF
(High frequency) The amount is significantly lower than that of a sputtering device called a sputtering method, and it does not become a cause of failure in ordinary hybrid integrated circuits.

FIG. 3 is a diagram showing the characteristics of the NiCr-Au electrode film deposited using a magnetron sputtering device, and (a) shows the resistance-temperature characteristics of the lead terminal bonded to the electrode film by thermocompression bonding means by actual measurements. (b) is an actual measurement of the tensile strength of the lead terminal bonded to the electrode film; (c) is an actual measurement of the solder erosion characteristics of the electrode film; The figure is a diagram for explaining the structure of the electrode film and how to measure the tensile strength.

In FIG. 4, 21 is an alumina substrate, 22 is a substrate 21
A tantalum nitride (TaN) layer is deposited on the top surface, 23 is a NiCr layer (about 400 mm thick) deposited on the top surface of the tantalum nitride layer 22, and 24 is a NiCr layer deposited on the top surface of the NiCr layer.
The lead terminal 25, which is a U layer (approximately 8,000 layers thick) and has a width Q of 3 mm and is made of Au-plated copper (Cu) material, was heated to approximately 400°C using a wedge with a width W of 0.2 m. The electrode film is crimped under certain conditions, and the tensile strength of the electrode film is the lead terminal peeling strength when the free end of the lead terminal 25 is pulled upward.

In Fig. 3 (A), the horizontal axis is the Ni used (Ni component ratio % of the target), and the vertical axis is the temperature coefficient T, C, Rpp.
m/℃, the solid line A is the temperature characteristic of the electrode layer, which is obtained by plotting the measured values and connecting them with a curve, and the temperature characteristic A is approximately Ni60.
% of the electrode layer using a NiCr target is ±0, and increases before and after that. Therefore, N of 60% Ni
The electrode film using the iCr target is the most excellent in terms of temperature characteristics.

In Figure 3 (II+), the horizontal axis is the Ni component ratio % of the NiCr target used, the vertical axis is the tensile strength of the lead terminal (kg), and the solid line B is the tensile strength characteristic plotted by plotting the measured values and connecting them with a straight line. B-3 is the tensile strength property when the electrode film is heat-treated at 275°C for 5 hours, and B-z is the tensile strength property when the electrode film is heat-treated at 275°C for 5 hours.
Tensile strength properties when heat treated at 50°C for 5 hours, B-3
B-4 is the tensile strength property when the electrode film is heat-treated at 200° C. for 5 hours, and B-4 is the tensile strength property when the electrode film is not heat-treated. And, while the tensile strength property B-4 is a nearly constant value, each of the tensile strength properties B-t~B shows the maximum value when a NiCr target with approximately 60% Ni is used. , an electrode film using a NiCr target containing 60% Ni is the most excellent in terms of tensile strength characteristics.

In Figure 3 (c), the horizontal axis is the Ni component ratio of the NiCr target used, and the vertical axis is the erosion of the solder deposited on the top surface of the electrode film (Au is diffused into the solder and disappears).
%, the solid line C is the solder erosion characteristic by plotting the measured values and connecting them with a straight line, C-I is the characteristic at the first solder dip, C-z is the characteristic at the second solder dip, C-8 shows the characteristics at the third solder dipping.

The electrode film deteriorates each time the solder dip is repeated, but the solder erosion characteristic C of the electrode film using a 70% Ni/NiCr target is the same as the deterioration caused by the first solder dip and repeated solder dips. ,
It is clear from FIG. 3 (c) that this method is superior to the others.

Therefore, in order to create an electrode film to which lead terminals etc. are connected by thermocompression bonding by magnetron sputtering, a NiCr target containing 60% Ni is used to create the best electrode film, as shown in Fig. 3 (a) and Fig. 3 (0). is obtained. On the other hand,
To create an electrode film used for soldering by magnetron sputtering, a NiCr target containing 70% Ni can be used to obtain the best electrode film.

FIG. 5 is a side cross-sectional view of a thin film capacitor according to an embodiment of the present invention, and FIG. 6 is a side cross-sectional view of an electrode film according to another embodiment of the present invention.

In FIG. 5, 31 is a glazed substrate, 32 is a substrate 3
A tantalum (α-Ta) layer formed on the upper surface of 1, 33 is a tantalum pentoxide (T) layer formed by anodizing a part of the α-Ta layer.
34 is a NiCr layer patterned on the Taos layer, 35 is an Au layer patterned on the NiCr layer 34, 36 is a NiCr layer patterned on the α-Ta layer 32, 37 NiCr The capacitor is constructed using the Ta05 layer 33, which is patterned on the layer 36 and has a thickness of approximately 1,500 to 3,000 layers, as a dielectric material, and the capacitor is composed of a film for forming at least the NiCr layers 34 and 36. is deposited by magnetron sputtering.

In this capacitor, the NiCr layers 34 and 36 are different from those deposited by conventional vacuum evaporation methods, and are not only uniform with no coarse deposited grains compared to the film thickness, but also have a uniform thickness when the deposited grains fly away. , because phenomena such as digging into the layer 32 do not occur, and because large thermal stresses such as those caused by vapor deposition are not applied, the pressure resistance is improved and the capacity per unit area is, for example, 5.
00 to 600 pF / 1000 pF
pF/va" level was achieved.

In FIG. 6, 41 is an alumina or glazed substrate;
42 is tantalum (tx-T) formed on the upper surface of the substrate 41.
a) layers, 43 is a NiCr layer patterned on CX-Ta N42, 44 is an intermediate layer with three patterns formed on the NiCr layer 43, and 45 is one layer patterned on the intermediate layer 44. The intermediate layer 44 is a NiCr-Au diffusion layer, a NiCr oxide layer, or a NiCr gas adsorption layer.

In such an electrode film configuration, a magnetron sputtering device is equipped with both a NiCr target and an Au target in the same bell jar, and the Au layer is sputtered immediately after the NiCr layer has been deposited (or with some overlap). When the formation film is deposited, a diffusion layer of NiCr-Au is created between the NiCr layer and the Au layer.

The electrode film having the NiCr-Au diffusion layer as the intermediate layer 44 is effective as an electrode film for soldering because the intermediate layer 44 prevents solder erosion.

On the other hand, in the electrode film for thermocompression, an intermediate layer 44 made of a NiCr oxide layer or a NiCr gas adsorption layer is interposed between the NiCr layer and the Au layer to prevent the diffusion of NiCr and Au. It is effective as an electrode film for thermocompression. Then, the Ni using the device
After completing the deposition of the NiCr layer, the Cr oxide layer and the gas adsorption layer are formed by applying NiC in an inert atmosphere at an appropriate pressure after creating a vacuum of approximately 7.3 Xl0-'Pascals.
By exposing it to the residual gas when sputtering r and Au, it can be formed to a thickness of about several tens of layers.

(g) As described in the detailed description of the invention, according to the present invention, at least nichrome (
The electrode film, which has a gold (Au) layer stacked on the bottom layer and a gold (Au) layer on the bottom layer, was deposited by the magnetron spunter method, making it possible to form the electrode film without impairing the quality of the deposited surface. This has made it possible to achieve higher performance and higher quality of thin film capacitors formed on substrates, and the effect of realizing a method for forming electrode films suitable for thermocompression bonding and soldering is extremely significant. big.

[Brief explanation of the drawing]

Figure 1 is an enlarged schematic diagram of a cross section of an electrode film formed on a hybrid integrated circuit, Figure 2 is a schematic diagram for explaining the outline of a magnetron sputtering device, and Figure 3 is a diagram of a magnetron sputtering device. Deposited NiCr-
A diagram for explaining the characteristics of the Au electrode film, FIG. 4 is a diagram for explaining the structure of the electrode film and how to measure the tensile strength, and FIG. 5 is a thin film capacitor according to an embodiment of the present invention. FIG. 6 is a side sectional view of an electrode film according to another embodiment of the present invention. In addition, in the figure, 1, 14, 2L31, 41 are substrates,
2゜22, 32.42 is a tantalum layer, 3 is an electrode film, 4.
23.34.36°43 is NiCr layer, 5,24,35
, 37.45 is an Au layer, 12 is a target, 44 is an intermediate layer (Au diffusion layer + NiCr oxide layer, NiCr gas adsorption layer), 'A-C indicates the characteristics of the electrode film. Mine 2 secrets σ 2θ # t V /g Nt'晟y(, li (λ) '#3uta (ro) θ d# bo 8θ lρθ (phantom #Q / (N'su α small 0 26 # 6o210 /at) A” / (Nt ft etc.) (2)

Claims (8)

[Claims] (1) At least a nichrome (NiCr) layer is used as a lower layer,
An electrode film characterized in that an electrode film on which a gold (Au) layer is laminated is deposited and formed by magnetron sputtering. (2) The electrode film according to claim 1, wherein the electrode film is an electrode film of a thin film hybrid integrated circuit. (3) A method for manufacturing an electrode film, characterized in that an electrode film having at least a nichrome (NiCr) layer as a lower layer and a gold (Au) layer as an upper layer is sequentially deposited and laminated by magnetron sputtering method. . (4) The composition of the target of the magnetron sputtering device for depositing the lower layer is about 60% nickel. (5) The composition of the target of the magnetron sputtering device for depositing the lower layer is approximately 70% nickel. (6) Nichrome (NiCr)-gold (
＾U) Method for manufacturing the polar film. (7) A method of forming an oxide layer of nichrome (NiCr) on the upper surface of the lower layer. (8) A manufacturing method in which nichrome (NiCr) gas is adsorbed on the upper surface of the lower layer.