JPS5816557A - Semiconductor device - Google Patents

Abstract

PURPOSE:To double the function of a semiconductor device by a method wherein two circuits mirror symmetric with each other are respectively incorporated into two semiconductor substrates and the substrates are installed in a package with their rear sides facing to each other. CONSTITUTION:Two semiconductor substrate 3a and 3b are respectively provided with circuits that are same in function and mirror symmetric with each other. The two substrates are installed on the both surfaces of a base ribbon island 5 so that the sides not provided with circuits may face each other mirror symmetry-wise. The semiconductor substrates 3a and 3b sandwiching the island 5 are housed in the cavity 8 of a package 9, and a lead 4 is bonded to pads, which results in the accomodation of two semiconductor substrates of the same function in a single package.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device, and in particular relates to the shape of a circuit formed on a semiconductor substrate and the position of mounting the substrate.

For the mounting of a semiconductor substrate on a package in a conventional semiconductor device, for example, the first W.
A ceramic package is shown in FIG. Conventionally, only one main surface (2a) of the surface was used for mounting a semiconductor substrate inside a package, and the back surface (2b) did not make a significant contribution to the function of the semiconductor device. Ta.

On the other hand, in the present invention, a semiconductor substrate (3b) on which a circuit that is mirror-symmetrical to the semiconductor substrate (3&) is built is mounted in a package so that the back side faces the semiconductor substrate (3m). By doing so, the functionality of the semiconductor device can be easily doubled without changing the size of the package.

The present invention will be explained by examples.

Figure 2 (2) and Figure 2 [@ are semiconductor devices according to one embodiment of the present invention, Figure 2 (■) is a plastic package with 5J
I2 Figure 0 shows an example implemented in the Seven Usec Package. Also, FIG. 3 (■) is an example of a semiconductor board having circuits that are mirror-symmetrical to each other, and FIG.
Figure 3 shows an example in which the semiconductor substrates shown in Figure 3) are mounted so that their backs are facing each other.

1) Example of application to plastic package Using an inverted mask, as shown in 3g (g), a semiconductor substrate (3b) having a circuit mirror-symmetrical to that of the semiconductor substrate (3a) is made, Two semiconductor substrates (3a, 3b)
are attached to both main surfaces of the base ribbon island section as shown in Fig. 2 (2). Since the two mounted boards are mirror-symmetrical to each other as shown in the third [@], the bonding pads having the same function are located directly behind each other. Therefore, those pads are bonded to the same lead.

However, the pads to which signals for selecting the substrates (3m, 3b) are input are connected to separate leads.

In this way, two devices with the same functionality in the same package
It is possible to install two boards in a state where each can be selected.

2) Example of application to ceramic package Two semiconductor substrates (with mirror-symmetrical circuits built into them)
3m, 3b) are fixed to a package having cavities on both main surfaces (2m, 2b) of the package so as to face each other from the back as shown in FIG. 20.

In the case of a plastic package, by bonding leads and pads to 48, two semiconductor substrates having the same function can be mounted in the same package in a state where each can be selected.

Next, examples of functional improvements obtained by implementing the present invention will be shown.

3) Example of increasing packaging density If the present invention is applied to a memory element such as an IC memory, two semiconductor substrates having the same function can be placed in the same package.
Since each t can be selected and installed in a usable state, it is possible to mount twice as many memory elements as in the past, and the memory capacity can be easily doubled.

4) Example of improving reliability By applying the present invention to logic elements such as microcomputers, two semiconductor substrates having the same function are mounted in the same package so that each can be selectively used. Select and use only one semiconductor substrate, and
By switching to the other semiconductor substrate when a jA failure occurs, it is possible to obtain twice the reliability compared to the conventional semiconductor substrate.

[Brief explanation of the drawing]

Part IWJ^ and Fig. 1
FIG. 2 is a cross-sectional view showing a conventional semiconductor device mounted only on the main surface side. #12 [^ and Figure 2 0 show a semiconductor device according to an embodiment of the present invention, in which two semiconductor substrates having mutually mirror-symmetrical circuits are fixed to the bidirectional side of the package in four ways with their backs facing each other. FIG. Note that % 1st tli, mzm
In both cases, (2) indicates the case of a plastic package, and @ indicates the case of a ceramic package. (see Figure 3)
3 is a front view of a semiconductor substrate having circuits mirror-symmetrical to each other, and FIG. FIG. In addition, in the figure, 1... bonding wire, 2a
... 1 main surface of the package, 2b... Opposite l main surface of the package, 3... Semiconductor substrate, 4... Lead, 5
... Pace ribbon island part, 6... Plastic package, 7... Cap, 8... Cavity. 9... Indicates a ceramic package.

Claims (1)

[Claims] Two semiconductor substrates with the same function, on which mirror-symmetrical circuits are built, are placed so that the sides on which no circuits are built face each other, and the sides on which circuits are built are almost mirror-symmetrical to each other. A semiconductor device characterized by being attached to a package in a similar manner.