Semiconductor devices are widely used in various types of electronic products, consumer products, automobiles, integrated circuit cards, and the like. One feature of semiconductor devices which is important in many of these applications is the small size of a semiconductor device. In addition to making individual semiconductor die (also referred to as chips) as small as possible, it is important that packages which house the die be kept to a minimum size also. Keeping device dimensions as small as possible is not only important to single chip devices, but to multichip devices as well.
In addition to establishing a small device size, manufacturers are also driven to maintaining a low cost of manufacturing devices. Multichip semiconductor devices are gaining popularity because multichip devices significantly increase device packing density on a substrate, for example on a printed circuit (PC) board. However, one aspect which is slowing industry acceptance of multichip devices is prohibitive manufacturing costs. Many multichip devices utilize expensive ceramic substrates and employ additive thin-film processing on semiconductor die, processes which significantly increase manufacturing costs. Due to the high cost associated with many existing multichip devices, semiconductor manufacturers are evaluating low-cost alternatives to multichip devices which utilize resin encapsulation.
Resin encapsulated semiconductor devices are usually packaged by either one of two methods. In one method, a semiconductor die, or a plurality of die, is placed in a package which is then individually mounted on a circuit substrate. In an alternate method, a semiconductor die, or a plurality of die, is mounted directly on the circuit substrate and then is provided with a protective encapsulation structure. The first mentioned method has the advantages that the die is sealed in and protected by the package. The packaged device is easy to test, handle, and install and the encapsulating package provides the desired degree of protection against the environment. In contrast, the second described method in which the die is connected directly to the substrate minimizes the area required by the die and thus allows a very high substrate packing density. In this method, however, an unpackaged die is less easily handled, tested, and burned-in, and is more subject to undesirable effects of the environment.
Thus a semiconductor device, and more specifically a multichip semiconductor device, and a method for its fabrication were needed which would overcome the limitations of the foregoing semiconductor devices and methods.