JPS63308333A - Connecting method for integrated circuit - Google Patents

Abstract

PURPOSE:To provide high superconducting transfer temperature and to realize an easy bonding by disposing a material pellet of ceramics of a superconductor at the connecting section of a superconductor ceramic electrode, and sintering it. CONSTITUTION:A pellet (e.g., material formed by sufficiently mixing powders of yttrium, barium carbonate and copper oxide) 5 of suitable superconducting ceramic material is disposed on the top of a wiring pad 4 to form a bump. Then, a superconducting ceramic lead 6 is disposed on the top of the bump 5, the pellet 5 is heated by a heater 7 having the same sectional area and shape as those of the pad, the lead 6 is retained under suitable pressure, and the pellet 5 is sintered. Thus, a superconductive bonding with its connecting strength is easily realized at high transfer temperature between an integrated circuit chip and package leads or between the leads and superconducting ceramic electrodes of a printed board or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for bonding integrated circuit devices using superconducting ceramics.

Conventional technology Integrated circuits using superconductors not only can significantly reduce the circuit time constant by using superconductors with zero electrical resistance in wiring, but also utilize various types of integrated circuits that utilize ultrafast Josephson switching elements and the Josephson effect. Due to the availability of highly functional devices, it is possible to operate at much higher speeds and with lower power consumption than ordinary semiconductor integrated circuits, and is being actively researched as a promising candidate for the next generation of ultra-high-speed integrated circuits. Unique devices unique to superconductivity, such as highly sensitive magnetic sensors that utilize the Meissner effect and quantum effects, have also been developed, and some have been put into practical use in fields such as medicine. The recent discovery of ceramic-based high-temperature superconductors is expected to further promote the practical application of these superconducting integrated circuits.

By the way, when a plurality of integrated circuits using these superconductors are used in combination, it is naturally possible to use superconductors for the interconnections between the integrated circuits. Examples include printed circuit boards using superconductors and packages with superconducting leads. In this way, by using superconductors not only in integrated circuits but also in their peripheral circuits, connection wiring, etc., it is possible to construct systems that are faster and consume less power.

However, bonding is not easy when mounting superconducting integrated circuits, such as connecting these integrated circuits and package leads, or connecting packages and printed circuit boards. Conventionally, in superconducting integrated circuits using niobium, the connection strength between the superconducting solder and the niobium was almost nonexistent, so measures were taken to increase the connection strength by providing an intermediate layer such as palladium.

Palladium has sufficient connection strength with niobium and also with solder, and has the excellent feature of not changing the melting point of the solder when it is alloyed with the solder, but since it is not a superconductor, it is an intermediate material. When used as a layer, the superconductivity at the connection part is broken, which hinders high-speed signal transmission between superconducting chips. Attempts have been made to use the superconductor tantalum as the intermediate layer, but the transition temperature of tantalum is 4.5, which is considerably lower than that of niobium, and the process of vapor deposition and patterning when forming the intermediate layer is difficult. A complicated process was required.

Considering the application of this to the implementation of integrated circuits using ceramic-based high-temperature superconductors (e.g., Y-Ba-Cu-○ compounds), which have been rapidly researched recently, it is possible to Compared to the extremely high transition temperature of conductors, the transition temperature at the connection is just around the temperature of liquid helium, which poses a major problem.

Problems to be Solved by the Invention As mentioned above, when constructing an integrated circuit system using superconductors, it is difficult to obtain connection strength using the conventional bonding method using different types of superconducting solder. This requires complicated processes such as providing an intermediate layer, and there are also problems such as the superconductivity breaking at the connection part or the superconducting transition temperature of the connection part being lower than that of other wiring parts. Ta.

In view of this point, the present invention has a high superconducting transition temperature,
Another purpose is to easily realize bonding.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a method for connecting superconducting ceramic electrodes by arranging a pellet of ceramic raw material that becomes a high-temperature superconductor of the same type at the connection part, and This is a bonding method in which the ceramic raw material is sintered into a superconductor by applying high temperature and high pressure to the part.

Effect of the Invention The present invention can realize superconducting bonding with high transition temperature and high connection strength between an integrated circuit chip and a package lead, or between a package lead and a superconducting ceramic such as a printed circuit board, by using the method described above. This makes it possible to connect the entire system, including its peripheral circuits, with superconductivity.

Embodiment FIGS. 1(a) to (e) show the first embodiment of the present invention.
FIG. 3 is a cross-sectional view showing the sequential steps of bonding an integrated circuit chip having a superconducting ceramic wiring pad and a package lead made of superconducting ceramic. Hereinafter, the explanation will be given in order according to the drawings. FIG. 1A shows a part of an integrated circuit, in which 1 is a substrate made of a semiconductor or the like, 2 is an insulating film layer, 3 is a superconducting ceramic wiring, and 4 is a wiring pad. First, as shown in the same figure (b), a pellet 5 of a suitable superconducting ceramic raw material (for example, a mixture of powders of yttrium, barium carbonate, and steel oxide) 5 is placed on top of the wiring pad to form a bump. do. Next, the same figure (
As shown in c), a superconducting ceramic lead 6 is placed on top of the bump 5, and as shown in FIG. For example, by applying heat of 800℃ to 1200℃ and applying pressure of about 100 kg, the lead 6
Press down together to sinter the pellet 5.

FIG. 6(e) shows a state in which bonding is completed through the steps described above. The raw material pellets are sintered to mechanically bond the wiring pads and package leads, and at the same time, the sintered ceramics become a superconductor 8, realizing electrically good superconducting connections. There is. In this way, unlike conventional bonding methods using superconducting solder, bonding is performed using the same material as the electrodes, making it possible to achieve strong bonding with good wettability. It becomes possible to connect all wiring using high-temperature superconductors.

In this embodiment, bonding of one lead and one wiring pad is shown, but it goes without saying that it can be easily applied to a method of bonding a large number of pads and leads at the same time, such as a film carrier method.

FIGS. 2(a) and (b) show a second embodiment of the present invention,
FIG. 3 is a cross-sectional view showing a bonding process between a packaged integrated circuit having superconducting ceramic leads and a printed circuit board having a conductive portion (wiring) made of superconducting ceramic. In the same figure (a), 21 is a printed circuit board, 22 is a superconducting ceramic wiring provided on the printed circuit board, and 23
1 is an integrated circuit package, 24 is a superconducting ceramic lead of the same package, and 25 is a superconducting ceramic raw material pellet similar to that shown in FIG. 1(b). Second
As shown in Figure (a), the raw material pellets are placed at the connection between the leads of the package and the wiring part on the printed circuit board, and then, as shown in Figure (b), the heater 26 is used to heat the first embodiment. Similarly, heat and pressure are applied to sinter the raw material pellet.

In the manner described above, superconducting mounting of an integrated circuit on a printed circuit board becomes possible.

In these examples, a method using contact pressure with a heater was used to sinter the superconducting ceramics, but other heating methods such as electric current heating, ultrasonic heating, microwave irradiation, laser irradiation, etc. May be used.

Effects of the Invention As described above, according to the present invention, a superconductor with a high transition temperature and a strong connection between an integrated circuit chip and a package lead, or between a package lead and a superconducting ceramic electrode of a printed circuit board, etc. Bonding can be easily realized, and superconducting connections can be made not only within integrated circuits but also throughout the entire system, including their peripheral circuits, and its practical effects are extremely large.

[Brief explanation of drawings]

FIG. 1 is a sectional view sequentially showing the steps of bonding an integrated circuit and package leads according to a first embodiment of the present invention, and FIG. 2 is a diagram showing the mounting of an integrated circuit on a printed circuit board according to a second embodiment of the present invention. It is a sectional view showing a process. 1... Substrate such as semiconductor, 2... Insulating film layer, 3...
...Superconducting ceramic wiring, 4... Pad part of the same wiring, 5... Superconducting ceramic raw material pellet, 6.
...Superconducting ceramic lead, 7...Heater,
8... Sintered ceramic superconductor, 21...
Printed circuit board, 22...Superconducting ceramic wiring, 2
3...Package, 24...Package lead, 25...Superconducting ceramic raw material pellet, 26...
···heater. Name of agent: Patent attorney Toshio Nakao and one other person

Claims (3)

[Claims] (1) In connecting electrodes made of superconducting ceramics, a method for connecting integrated circuits, characterized in that pellets of raw material for ceramics that will become a superconductor are placed in the connection portion, and the raw material for ceramics is sintered. (2) Claims characterized in that the connection is a connection between the wiring pad of an integrated circuit having a wiring pad made of superconducting ceramics and the wiring lead of a package having wiring leads made of superconducting ceramics. A method for connecting an integrated circuit according to item 1. (3) The integrated circuit according to claim 1, wherein the connection is a connection between a package having wiring leads made of superconducting ceramics and a printed circuit board having a conductive part made of superconducting ceramics. Connection method.