Active solid-state devices (e.g. – transistors – solid-state diode – Physical configuration of semiconductor – With electrical contact in hole in semiconductor
Reexamination Certificate
2001-11-29
2004-08-24
Vu, Hung (Department: 2811)
Active solid-state devices (e.g., transistors, solid-state diode
Physical configuration of semiconductor
With electrical contact in hole in semiconductor
C257S698000, C257S735000, C257S774000
Reexamination Certificate
active
06781215
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an intermediate base for a module having at least one semiconductor component. The base comprises a flat base body having an upper face on which internal connections are formed for connection to connecting elements of the semiconductor component, a lower face, which is provided with external connections for making contact with a circuit base, carrier or board and through-holes extending between the upper face and the lower face, whose walls are at least partially metallized to make connections between the internal connections on the upper face and the corresponding external connections on the lower face. The invention also relates to the semiconductor module produced using this intermediate base and to the method for producing the intermediate base.
The increasing miniaturization of integrated circuits has led to the problem that an even greater number of electrical connections need to be accommodated in a very confined space between the actual semiconductor and the circuit carrier or base, that is to say the printed circuit board. However, the finer the structures of the semiconductor chip and of the connecting conductors, the greater is the extent to which they are at risk from different expansion levels of the materials involved, in particular the semiconductor body and the printed circuit board, which is composed of plastic.
The intermediate base or interposer plays a great role in making contact with a semiconductor chip. It allows one or more chips to be connected to form a module, with which contact is then made on the circuit carrier or board.
In the case of what is referred to as a BGA (Ball Grid Array) technology, an intermediate base is provided over the area of its lower face with solder studs, which allow surface mounting on a printed circuit board. The solder studs are, in this case, first used as electrical connections and secondly are used as spacers to compensate for expansion between the different materials of the intermediate base and printed circuit board. The conductor chip can be mounted on the upper face of the intermediate base, and contact can be made with it, for example, by means of bonding wires. Flip chip mounting is also known, in which the connections of the unhoused semiconductor are directly connected to conductor tracks on the upper face of the intermediate base. In order to provide expansion compensation between the semiconductor body and the intermediate base in this case, underfilling is generally required for the semiconductor, which involves the necessity for additional, complicated and expensive processing steps, which also do not allow subsequent repair.
In the case of what is referred to as PSGA (Polymer Stud Grid Array) technology, the injection-molded, three-dimensional substrate composed of an electrically insulating polymer is used as the intermediate base, on whose lower face polymer studs are arranged over the surface, which are integrally formed during the injection molding process. Examples of this are shown in U.S. Pat. Nos. 5,929,516 and 6,249,048, whose disclosures are incorporated herein by reference thereto, and by the corresponding European Patent EP 0 782 765. These polymer studs are provided with an end surface which can be soldered and form external connections which are connected via integrated conductor runs to internal connections for the semiconductor component which is arranged on the substrate. The polymer studs are used as spacers for the module from a printed circuit board and are, thus, able to compensate for different expansion levels between the printed circuit board and the intermediate base. Contact can be made with the semiconductor component on the upper face of the intermediate base via bonding wires; however, a form of contact making is also feasible in which the different thermal coefficients of expansion are compensated for in an analogous manner via polymer studs on the upper face of the intermediate base.
In addition, a single-chip module is know from U.S. Pat. No. 5,069,626, whose disclosure is incorporated herein by reference thereto, and from WO 89/00346. As disclosed by these references the injection-molded three-dimensional substrate composed of an electrically insulating polymer has integrally formed polymer studs on the lower face which are arranged in one row or in a number of rows along the circumference of the substrate. One chip is arranged on the upper face of the substrate and contact is made with it via fine bonding wires and conductor tracks, which are then, themselves, connected via plated through-holes to the external connections formed on the lower-face studs. In this embodiment, the intermediate base has a relatively large extent.
SUMMARY OF THE INVENTION
The object of the present invention is to provide an intermediate base for a semiconductor module, a production method for forming the intermediate base and a module in which contact can be made directly with the semiconductor component without any underfilling on the intermediate base and contact can be made with the intermediate base on the circuit carrier or base without any additional measures, and in which the different coefficients of expansion of the materials that are used do not have any apparent disadvantageous effect. In this case, the semiconductor component together with the intermediate base are intended to produce a module with a very compact physical form.
According to the invention, the first part of the object is achieved by an intermediate base for a module having at least one semiconductor component. The base comprises a flat base body having an upper face on which internal connections are formed for connection to component connecting elements of a semiconductor component, a lower face, which is provided with external connections for making contact with a circuit carrier, and through-holes between the upper face and the lower face, whose walls are at least partially metallized, and each makes a conductive connection between a contact point on the upper face and a corresponding external connection on the lower face, with the walls of the through-holes being at least partially exposed in the region of the lower face of the base body by means of annular notches or grooves, which are incorporated adjacent to a circumferential edge of the through-hole and form a freestanding stud as the external connection.
The production of the stud by means of notches or grooves on the lower face of the intermediate base, as provided according to the invention, results in them being arranged recessed in the lower face surface and not projecting, or only their metallized layers project beyond the surface. Nevertheless, the studs are able to absorb and to compensate for temperature-dependent different expansion levels of the intermediate base, on the one hand, and on the circuit carrier or board, on the other hand. Contact is made via a short route through the metallized holes which run within the polymer stud to the upper face of the intermediate base, where the semiconductor component or else a number of semiconductor components is/are arranged, and contact is made with the internal connections.
The through-holes are preferably formed concentrically within the studs, so that the latter has a tubular or chimney-like configuration. However, an eccentric arrangement between the through-holes and the stud is also feasible, so that the latter approximately has the form of a tubular segment.
A particularly compact construction can be achieved if the intermediate base according to the invention is formed by a film composed of a plastic material, whose coefficient of expansion is approximately the same as that of the semiconductor component, which is generally silicon. In this case, the semiconductor component can be placed with its component connecting elements directly onto the internal connections on the upper face of the through-holes and can make contact therewith. This means that no connecting conductors whatsoever in the form of bonding wires or conductor tracks are re
Schiff & Hardin LLP
Siemens Aktiengesellschaft
Vu Hung
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