Semiconductor sensor component including a sensor chip and methods for the manufacturing thereof

A semiconductor sensor component including a sensor chip and methods for the manufacturing thereof is disclosed. In one embodiment, the semiconductor sensor component includes a package which itself includes a transparent plastic material. The sensor chip has an active top side and a back side, wherein a sensor area is arranged on the active top side and flipchip contacts are provided outside of the sensor area on the active top side. These flipchip contacts are electrically connected to a circuit structure, wherein the circuit structure allows free access to the sensor area. The sensor chip including the sensor area and the flipchip contacts and a part of the circuit structure which is electrically connected to the flipchip contacts are embedded in the transparent plastic material, wherein the transparent plastic material includes a rubber-elastic substance.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Utility Patent Application claims priority to German Patent Application No. DE 10 2005 025 754.2 filed on Jun. 2, 2005, which is incorporated herein by reference.

BACKGROUND

The invention relates to a semiconductor sensor component including a sensor chip and methods for the manufacturing thereof. The semiconductor sensor component additionally includes a package in which is arranged the sensor chip including its active top side and a back side, the sensor chip being electrically connected to a circuit structure of the package.

FIELD OF THE INVENTION

Such a sensor component is disclosed in the publication DE 102 05 127. In the known sensor component, the sensor chip includes flipchip contacts and a sensor area, wherein the flipchip contacts are arranged on the active top side in a peripheral area outside of the sensor area and the sensor chip including its flipchip contacts is embedded in a non-transparent plastic package material, wherein the flipchip contacts are electrically connected to a wiring structure which itself includes an opening such that the sensor area is freely accessible. An annular metal structure is arranged around this opening, surrounding the sensor area and being fixed directly onto the active top side of the sensor chip and onto the circuit structure. The sensor chip, including its back side, edge sides and the areas in which the flipchip contacts are arranged on the active top side, is embedded in a non-transparent plastic package material.

Such a semiconductor sensor component has the disadvantage that the thermal expansion coefficient of the non-transparent plastic package material is greater than the thermal expansion coefficient of the sensor chip, and therefore significant strain occurs under thermal load. Moreover, the sensor chip is rigidly mechanically connected to the circuit structure by the metallic ring around the sensor area, such that no provision is made for mechanical separation between the sensor area and circuit structure and therefore package stresses are transmitted directly onto the sensitive area of the active top side of the sensor chip. This results in a significant tolerance in the sensor characteristics of such semiconductor sensor components.

However, there is a requirement to minimize the tolerance in the sensor characteristics of the sensor components in a production lot in order to increase the reliability of the sensor components.

SUMMARY

The present invention provides a semiconductor sensor component including a sensor chip and methods for the manufacturing thereof. In one embodiment, the semiconductor sensor component includes a package which itself includes a transparent plastic material. The sensor chip has an active top side and a back side, wherein a sensor area is arranged on the active top side and flipchip contacts are provided outside of the sensor area on the active top side. These flipchip contacts are electrically connected to a circuit structure, wherein the circuit structure allows free access to the sensor area. The sensor chip including the sensor area and the flipchip contacts and a part of the circuit structure which is electrically connected to the flipchip contacts are embedded in the transparent plastic material, wherein the transparent plastic material includes a rubber-elastic substance.

DETAILED DESCRIPTION

The present invention provides a semiconductor sensor component and a method for the manufacturing thereof, wherein the component allows greater separation between sensor area and circuit structure and can be manufactured at lower manufacturing costs while offering greater reliability.

According to one embodiment of the invention, a semiconductor sensor component including a sensor chip and a package is provided. This package includes a transparent plastic material. The semiconductor chip has an active top side and a back side, wherein the active top side illustrates a sensor area. Flipchip contacts are arranged outside of the sensor area on the active top side of the semiconductor chip. These flipchip contacts are electrically connected to a circuit structure. In this case, the circuit structure is arranged such that it allows free access to the sensor area. The semiconductor chip with sensor area, the flipchip contacts and that part of the circuit structure which is electrically connected to the flipchip contact are embedded in the transparent plastic material. The transparent plastic material includes a rubber-elastic substance.

This semiconductor sensor component has the advantage that it includes a relatively compact construction, and an extensive mechanical separation between the circuit structure and the sensor chip is ensured. A further advantage is that the semiconductor chip, the sensor area, the flipchip contacts and that part of the circuit structure which is electrically connected to the flipchip contacts can be embedded with relative ease in a transparent rubber-elastic plastic material in order to form the package.

In order to improve the dimensional stability of the package of the semiconductor sensor component, a preferred embodiment of the invention provides for surrounding the transparent plastic material at least on the edge sides by a package frame of a non-transparent plastic package material while leaving the sensor area free. This non-transparent plastic frame is correspondingly distant from the central sensor area of the sensor chip and is used for positioning and retaining the circuit structure and for delimiting the transparent plastic material on its edge sides. Furthermore, the non-transparent relatively rigid plastic package material facilitates the incorporation or embedding of the sensor chip with flipchip contacts and parts of the circuit structure into the transparent plastic material.

In a one embodiment of the invention, the circuit structure has flat conductors, wherein outer flat conductors project outwards from the package and merge into inner flat conductors which are arranged within the transparent plastic material, wherein the flipchip contacts are fixed onto the inner flat conductors and the transparent plastic package material embeds the inner flat conductors, the flipchip contacts, the sensor area and the sensor chip.

This embodiment of the invention has the advantage that the flat conductors can be formed as thin metal film strips such that the flipchip contacts which are fixed onto them and the sensor chip in the rubber-elastic transparent plastic material are freely moveable and consequently a mechanical separation is made possible in relation to a rigid package frame of non-transparent plastic package material. In this case, the inner flat conductors are structured in such a way that they extend from the outer flat conductors through the transparent rubber-elastic plastic package material only as far as the flipchip contacts, such that the sensor area remains freely accessible for optical waves and compressional waves. In this case, the transparency of the transparent plastic material allows an optical link between sensor area and environment, and the rubber-elastic properties of the plastic package material ensure that compressional waves reach the sensor area and can be converted by the sensor area into corresponding electrical signals which can then be transmitted via the flipchip contacts and the relatively flexible film-type metallic inner flat conductors to the stable outer flat conductors.

In another embodiment of the invention, a TAB film (a film for “tape automated bonding”) is used as a circuit structure. For this, the TAB film has an opening which corresponds in its surface extent to the sensor area of the sensor chip, such that access to the sensor area advantageously remains free for optical or pressure-based measurement objects. Around the opening, the film additionally has contact terminal pads to which the flipchip contacts are fixed. As a result of the inherent flexibility of the TAB film including the contact terminal pads and conductor paths which are situated thereon, a mechanical separation is also achieved between electrical leads and sensor area via the flipchip contacts in this second embodiment of the invention. In order to carry the electrical measurement signals to the exterior of the semiconductor sensor component by means of the TAB film, external contact pads are arranged on the external side of the film, thereby forming external contacts of the semiconductor sensor component.

In another embodiment of the invention, the circuit structure has a wiring substrate, wherein the wiring substrate has an opening which corresponds in its surface extent to the sensor area of the sensor chip. Such a wiring substrate does not have the flexibility of a TAB film, but a rigid wiring substrate can nonetheless be advantageous in certain application scenarios, e.g. in order to maintain a reference level or a reference surface as a reference level in the case of pressure measurements, such that the sensor chip can perform vibrational oscillations at least in the sensor area. Again in the case of the wiring substrate, contact terminal pads to which the flipchip contacts are fixed are advantageously arranged in the peripheral area of the opening.

In the case of the TAB film and the wiring substrate as coupling elements between the flipchip contacts and external contacts, external contact pads are arranged on the respective underside of the TAB film on corresponding external contact pads or on the underside of the wiring substrate, and external contacts of the semiconductor sensor component are fixed thereto. Such external contacts can preferably be surface-mountable soldering globules. Such surface-mountable soldering globules have the advantage that the footprint on a superordinate circuit board need be no larger than the external dimensions of the semiconductor sensor component, in particular since the whole underside of the semiconductor sensor component can be populated with such soldering globules as far as the opening which must be kept free towards the sensor area. Furthermore, the underside of the wiring structure can include a structured solder resist layer which leaves external contact pads free, wherein the structured solder resist layer ensures that the conductor paths to the contact terminal pads within the semiconductor sensor component are not wetted during the surface assembly.

A method for manufacturing semiconductor sensor components corresponding to the first embodiment of the invention has the following method processes.

A semiconductor wafer is manufactured including a plurality of sensor chip positions which are arranged in rows and columns, wherein the active top sides in the sensor chip positions have sensor areas and contact pads and wherein the back sides are arranged on the back side of the semiconductor wafer and opposite to these active top sides. Still at the wafer level, flipchip contacts outside of the sensor area can be mounted on the active top sides of the semiconductor chips in the sensor chip positions. The semiconductor wafer is then divided into sensor chips having flipchip contacts.

Independently of the manufacture of a semiconductor wafer, a flat-conductor frame including a plurality of semiconductor component positions is prepared as a circuit structure for the first embodiment of the invention. Package frames of a non-transparent plastic package material are mounted in the individual semiconductor component positions on this flat-conductor frame, wherein the side walls of a package frame for a semiconductor sensor component package are formed including inner flat conductors which project into the package frame and outer flat conductors which project out of the package frame. The flat-conductor frame including a plurality of semiconductor component positions is then populated with sensor chips within the package frames, fixing the flipchip contacts onto the inner flat conductors of the flat-conductor frame and leaving the sensor areas free.

The sensor chips including the sensor areas, the flipchip contacts and the inner flat conductors are then embedded in a transparent plastic material within the package frame. Finally, the flat-conductor frame can then be divided into individual semiconductor sensor components. This method has the advantage that a semiconductor sensor component or a plurality of semiconductor sensor components is/are produced in a simple manner using standard method processes while nonetheless allowing different expansion of the transparent plastic package material within the rigid frame of non-transparent plastic package material, wherein the sensor areas and sensor chips of the semiconductor sensor component(s) are mechanically separated from the rigid package frame, the inner flat conductors having a film-type cross section in order to ensure this mechanical separation.

The division of the flat-conductor frame is preferably carried out by means of stamping, which is a proven technology, in order to dice the flat-conductor frame.

In a method for manufacturing a semiconductor sensor component corresponding to the second embodiment of the invention, the sensor chips with flipchip contacts and sensor areas are initially produced from a semiconductor wafer in exactly the same way as during production of semiconductor sensor components as per the first embodiment of the invention. Instead of a flat-conductor frame, however, a TAB film with a plurality of semiconductor component positions is prepared as a circuit structure, wherein the TAB film has openings in the semiconductor component positions, the openings corresponding in their surface extent to the sensor areas of the sensor chips.

Such openings are not usual in conventional TAB films, but can be incorporated in a conventional TAB film by means of a simple stamping or cutting process. The mounting of sensor chips onto the top side of the TAB film, fixing the flipchip contacts to contact terminal pads of the top side of the TAB film in the area of the openings, can preferably be carried out using an automatic insertion machine. The sensor chip including the sensor area, the flipchip contacts and that part of the TAB film in the area of the openings are then embedded in a transparent plastic material. External contacts can then be mounted on corresponding external contacts of the TAB film on the back sides or undersides of the TAB film. Finally, the TAB film is divided into individual semiconductor sensor components. This method provides a semiconductor sensor component which allows the most advantageous mechanical separation yet between sensor chip and sensor package.

A method for manufacturing semiconductor sensor components corresponding to the third embodiment of the invention has the following method processes.

The same method processes as in the two previous methods are carried out in order to manufacture the sensor chips themselves, while the preparation of a wiring substrate including a plurality of semiconductor component positions as a circuit structure differs from the previous method processes. Specifically, openings which are not conventionally usual are incorporated in the semiconductor component positions in the wiring substrate, wherein the surface extent of the openings corresponds at least to the sensor areas of the sensor chips. The top side of the wiring substrate is then fixed to the sensor chips in the area of the openings, fixing the flipchip contacts onto corresponding contact terminal pads on the top side of the wiring substrate.

The sensor chips including the sensor area, the flipchip contacts and the wiring substrate in the area of the openings are then embedded in a transparent plastic package material. External contacts can then be mounted on external contact pads of the underside of the wiring substrate, before the wiring substrate is finally divided into individual semiconductor sensor components.

In this embodiment of the invention, it is again advantageous if the insertion of sensor chips in semiconductor component positions is carried out by means of an automatic insertion machine, wherein the sensor chips including their active top sides and flipchip contacts are fixed onto the circuit structure by means of soldering. For this, the top side of the wiring substrate includes a solder resist layer which leaves only the contact terminal pads free and prevents corresponding conductor paths of the wiring structure of the wiring substrate from being wetted with material from the flipchip contacts.

The embedding of the sensor chips in a transparent plastic material can be done advantageously by means of dispensing techniques. The deposition of a package frame of a non-transparent relatively rigid plastic package material, forming side walls on the transparent plastic package material, can be done advantageously by means of injection molding techniques for a plurality of semiconductor sensor components on the wiring substrate. The deposition of a wiring structure on the top side of the TAB film or on the top side of the wiring substrate can be done by depositing a continuous metal layer and then structuring by means of photolithography and etching techniques.

In summary, the manufacture of the sensor package for mounting flipchip contacts allows many different possibilities for a flexible connection between semiconductor sensor chip and package. In this case, anisotropically conductive adhesive films and TAB films can be used for inexpensive assembly designs.

The cover height above the sensor area can be checked more easily and therefore a narrower window for the sensor properties is possible. It is also possible to achieve a flatter package because no bonding wires are required for connecting the sensor chips to the circuit structure. Consequently, this invention clearly improves the possibilities relating to assembly and reduced divergence of the sensor sensitivities.

FIG. 1illustrates a schematic cross section through a semiconductor sensor component1corresponding to a first embodiment of the invention. The semiconductor sensor component1includes a sensor chip3including a back side7and an active top side6, wherein a sensor area8is arranged on the active top side6and contact pads27are present in the peripheral area of the active top side6. Fixed onto the contact pads27of the active top side6of the semiconductor chip3are flipchip contacts9, via which the semiconductor chip3or the active top side6of the semiconductor chip3is connected to a circuit structure10consisting of flat conductors15. This circuit structure10of flat conductors15includes thin flexible inner flat conductors17and reinforced outer flat conductors16which also represent the external terminals for the semiconductor sensor component1. The flat conductors15of the circuit structure10are held in position by a rigid package frame13made of a non-transparent plastic package material14.

Within the package frame13, the semiconductor sensor component includes a transparent rubber-elastic plastic material5as a package4of the semiconductor sensor component1, wherein the inner flat conductors17and the whole sensor chip3including its back side7, its edge sides29and30, its active top side6, the central sensor area8, the peripheral areas and the flipchip contacts9which are arranged thereon are embedded in the transparent rubber-elastic plastic material5. This embedding of the whole sensor chip3in a rubber-elastic transparent plastic material5has the advantage that a mechanical separation from the outer flat conductors16and the rigid package frame13is possible. The transparent rubber-elastic plastic material with its edge sides11and12abuts the rigid package frame13. The sensor area8, which is kept clear of the inner flat conductors17, can therefore detect both optical and mechanical waves and transmit the waves as measurement signals on the outer flat conductors16via the flipchip contacts9and the inner flat conductors17.

FIG. 2illustrates a schematic longitudinal section along the section line A-A fromFIG. 1through the semiconductor sensor component1. It can be seen from this longitudinal section that the sensor chip3with its edge sides29to32is embedded in the rubber-elastic transparent plastic material5, and is completely surrounded by this rubber-elastic transparent plastic material5, in a manner which allows full freedom of vibration. The inner flat conductors17are illustrated by means of broken lines and are formed correspondingly as thin film strips in order to ensure a mechanical separation between the rigid package frame13and the flipchip contacts which are not visible inFIG. 2.

FIG. 3illustrates a schematic cross section through a semiconductor sensor component2corresponding to a second embodiment of the invention. Components having identical functions as inFIGS. 1 and 2are identified by means of the same reference numerals and are not discussed separately.

In this embodiment of the invention, the circuit structure10is implemented by means of a wiring substrate23and/or by means of a TAB film. In the case of the wiring substrate23, the flexibility relative to the sensor chip3is less than in the first embodiment of the invention. If the wiring substrate23is replaced by a TAB film, however, it is possible to achieve mechanically extremely flexible connections to the external terminals of the semiconductor sensor component2.

In the case of the wiring substrate23, a wiring structure33is arranged on the top side24of the wiring substrate23as illustrated inFIG. 3. This wiring structure33has contact terminal pads19which are connected via conductor paths34to through contacts35through the wiring substrate23, wherein external contact pads21are arranged on the underside20of the wiring substrate23and carry external contacts22in the form of soldering globules25in this embodiment of the invention. The external contacts21are delimited locally by means of a surrounding solder resist layer26on the underside20of the wiring substrate23. Opposite to the sensor area8of the semiconductor chip3, provision is made in the wiring substrate23for an opening18whose surface extent corresponds to the surface extent of the sensor area8such that optical waves can reach the sensor area8by virtue of the transparency of the rubber-elastic and transparent plastic material5of the package4.

FIG. 4illustrates a schematic longitudinal section along the section line B-B fromFIG. 3through the semiconductor sensor component2. Again in this case, the sensor chip3is completely surrounded by transparent and rubber-elastic plastic material5, wherein a rigid package frame13provides the lateral delimitation of this rubber-elastic and transparent plastic material5at the edge sides11,12,37,38. This rigid package frame13has a plastic package material14which is arranged on the top side24of the wiring substrate23as illustrated inFIG. 3. Consequently, the edge sides29,30,31,32of the sensor chip3are completely surrounded by the transparent plastic material5and arranged at a distance from the rigid package frame13.

FIG. 5illustrates a schematic bottom view of the semiconductor sensor component2fromFIG. 3. The broken line36illustrates the outline of the rigid package frame13, while the opening18in the center of the wiring substrate23is filled by the transparent plastic material5. External contacts22in the form of soldering globules25are arranged on the underside20of the wiring substrate23and represent the external contacts22of the semiconductor sensor component2, such that the respective measurement signals can be picked up or supply voltages applied to the sensor chip at these points.