JPS5818954A - Manufacture of hybrid integrated circuit - Google Patents

Abstract

PURPOSE:To easily obtain a Ta capacitor with high heat-proof and reliability, by a method wherein an alpha-Ta capacitor is directly mounted on the ceramic substrate. CONSTITUTION:On a ceramic substrate (1) by a sputtering method is covered alpha- Ta film (2) of some 5,000Angstrom of thickness, where a resist (3) is mounted and Ta film (2) is opened. Then, a resist (4) is mounted and anodic oxidation is performed, and a part of film (2) is converted to a dielectric film (5). Again, by means of sputtering method, some 900Angstrom of Ta film (6) is covered overall therewith, a resist (7) is mounted to remove Ta film (6) by means of etching aq., and succeedingly a resist (8) is mounted and performs anodic oxidation to convert to a dielectric layer (5'). Removing a resit (8), a thin film (9) overlaid Ni, Pd and Au with films of each 1,000,1,000, and 6,000Angstrom is sputtered to make an electrode pattern. Owing to this constitution, even on the natual surface of the ceramic substrate with no graze, an alpha-Ta capacitor with a high yield and high thermal resistance may be provided by low cost and high reproducibility, by no means inferior to forming on the graze.

Description

[Detailed description of the invention] The present invention relates to a method of manufacturing a hybrid integrated circuit.

In recent years, beta-tantalum capacitors using valve metals such as tantalum, niobium, and titanium, especially tantalum, have been widely put into practical use. The dielectric oxide is extremely stable physically and chemically, and the dielectric oxide film thickness can be controlled with good reproducibility by changing the anodizing conditions, resulting in high reliability. This is because a thin film capacitor with strict capacitance accuracy can be easily realized.

In hybrid integrated circuits, thermocompression bonding methods are often used to form circuits, mount individual components, or connect external leads. To perform thermocompression bonding,
At least the crimping part must be on the bare surface of the substrate without glazing.

This is because the adhesion of the deposited metal layer to the glazed surface is insufficient. Further, in the case of a CR laance hybrid integrated circuit, it may be necessary to form it on an anglaise due to the circuit function characteristics such as the resistor's Ω/portion and resistance temperature coefficient.

However, beta-tantalum capacitors have the disadvantage of being easily affected by heat and having poor heat resistance, and therefore, as mentioned above, in order to obtain high reliability, it is necessary to form the capacitor on a glaze.

Therefore, as a ceramic substrate, it is necessary to use a so-called partially glazed substrate in which a glaze is printed on a predetermined portion. This has material disadvantages such as the expensive substrate and the increased unit price of thin film capacitors. Further, since the glaze has a thickness of several micrometers, a step is created with respect to the anglaze surface. This means that when the photomask and the substrate surface are brought into close contact, the glaze surface will be in close contact with the mask, but a gap will be created between the unglazed surface and the photomask, which will reduce the uniformity of the amount of light, K, and the designed pattern width. However, reproducibility cannot be obtained. As described above, the use of a partially glazed substrate has disadvantages such as an increase in material costs, a decrease in yield, and a restriction on the degree of freedom in circuit design.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for manufacturing a hybrid integrated circuit that eliminates the above-mentioned drawbacks due to substrate surface glaze and includes a process for forming a highly reliable tantalum capacitor with sufficient heat resistance.

The method of the present invention includes the step of forming an alpha tantalum capacitor directly on the bare surface of a ceramic substrate.

Alpha tantalum capacitors have superior heat resistance compared to beta tantalum capacitors, which conventionally had to be formed on a glaze due to heat resistance issues, so they can be formed directly on the bare surface of a ceramic or substrate without a glaze. too,
High reliability is maintained.

Next, the present invention will be explained by examples.

FIGS. 1(a) to 1(k) are cross-sectional views showing the manufacturing process of an embodiment of the present invention. First, we installed a DC 2-pole sputtering device with 5
After evacuation to a degree of vacuum of X10 Torr or more, argon gas is introduced from the outside to create an argon gas atmosphere of several tens of mTorr, and nitrogen and hydrogen gas are further introduced. Then, the tantalum cathode plate and the thoroughly cleaned ceramic substrate are
By maintaining a distance of 10 degrees and causing an abnormal glow discharge between both electrodes, a film thickness of 4000 to 56 mm was obtained, as shown in Figure 1 (,).
An alpha-tantalum thin film 2 of λ is deposited on a ceramic substrate 1. Next, as shown in the same figure (b), a photoresist 3 is applied to the entire surface of the tantalum thin film 2 to a thickness of several μm.
After forming a pattern using a known etching technique, as shown in FIG. Stir in a mixture of acid, nitric acid, and water. After the etching edges and the photoresist 3 are removed, a photoresist 4 is applied and patterned so that a predetermined region of the tantalum thin film 2 can be anodized, as shown in FIG. 3(d). Furthermore, a part of the tantalum thin film was heated at 0.5 mA in a 0.01% citric acid aqueous solution.
After constant current formation at /ct/l, constant voltage formation at 120V for 10 minutes is performed to convert the dielectric layer 5 into a dielectric layer 5 as shown in FIG. Next, after evacuating the DC two-pole spacing device to a vacuum level of 5 x 10 Torr or more, sialbone gas was introduced externally and
Create an argon gas atmosphere of rr, and then introduce Koji gas.

Then, 3 to 10 tantalum shade plates and ceramic substrates 1 are
By keeping the distance at 0 and causing an abnormal glow discharge between both electrodes,
As shown in FIG.
! A tantalum thin film 6 having a thickness of 700 to 900 Å is deposited on the entire surface of the tantalum film 2 and the dielectric layer 5. Next, as shown in FIG.
After coating the tantalum thin film 6 to a thickness of 7.m and forming a pattern using a known photoetching technique, the tantalum thin film 6 other than the predetermined area is etched as shown in FIG. 7(h). After etching with a mixture of acid, nitric acid, and water to remove the etched edges and photoresist cysts 7, a photoresist 8 is applied as shown in FIG. pattern the photoresist. Furthermore, a part of tantalum thin J[2 was added to 0.5
After constant current formation at mA/cj, constant voltage formation at 160V for 2 hours is performed to convert it into a dielectric layer 5', as shown in Figure 0)K, and the photon resist 2 is peeled off. Next, in the same figure (k
), a film thickness of 1000 mm was applied to the entire surface of the above structure.
A conductor thin film 9 having a three-layer structure of nichrome, baladium, and gold with a thickness of λ, 100 OA, and 6000 amps is removed, and then electrodes are patterned by photoetching.

Table 1 shows the yield of tantalum thin film capacitors formed on a bare substrate surface and on a glaze. You can obtain a tank 4M capacitor with a high yield comparable to that of its compatriots.

4. Brief explanation of the drawing
(6) FIGS. 1(a) to 1(k) are cross-sectional views for explaining the manufacturing process in one embodiment of the present invention.
(C) l...ceramic substrate, 2
, 6... Tantalum thin film, 3, 4, 7, 8...
...7 Otoregist, 5, 5' (1)・
... Equilibrium oxide dielectric layer, 9 ... Conductor thin film.

Agent Patent Attorney Susumu Uchihara (e
)(() Fig. 1 235-

Claims (1)

[Claims] A method for manufacturing a hybrid integrated circuit, comprising the step of forming an alpha-tantalum capacitor on a bare surface of a ceramic substrate.