Active solid-state devices (e.g. – transistors – solid-state diode – Responsive to non-electrical signal – Physical deformation
Reexamination Certificate
1999-11-16
2002-04-09
Wilson, Allan R. (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Responsive to non-electrical signal
Physical deformation
C257S417000, C257S420000, C257S723000
Reexamination Certificate
active
06369435
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention concerns a semiconductor component with at least one pressure sensor and a semiconductor chip having a semiconductor structure for at least one additional function of the semiconductor component and with a casing attached to the semiconductor chip.
Such a semiconductor component is known from R. Frank, “Pressure sensors merge micromachining and microelectronics,”
Sensors and Actuators
, A28(2), pp. 93-103 (1991). It has a semiconductor chip in whose substrate is etched a recess from the rear side, thus reducing the wall thickness of the semiconductor chip in some areas. Therefore, in the area of the recess, this yields a membrane of semiconductor material arranged in the surface plane of the semiconductor chip on the front flat side of the semiconductor chip, so that it can be deflected by a pressure acting against the restoring force of the semiconductor material. A measuring bridge arranged on the membrane has wire strain gauges to measure the bending deformation of the membrane caused by the acting pressure. The semiconductor chip also has a semiconductor structure for additional functions of the semiconductor component. This includes a circuit for temperature compensation of the pressure sensor and a microcomputer with a memory and an input/output interface for communication with an external computer.
The previously known semiconductor component has the disadvantage that a relatively large chip area must be reserved on the semiconductor chip for the membrane, thus increasing the cost of manufacturing the semiconductor component. Another disadvantage is that the membrane is under bending stress with the acting pressure, and the bending stresses are propagated into regions of the semiconductor chip near the membrane and can alter the electric properties of the semiconductor structure there. Thus, crystal planes in the structure may undergo mechanical deformation with the pressure acting on the membrane, for example, thus resulting in electric potentials in the semiconductor material which can alter the off-state voltage of pn junctions in the structure, for example. The additional function of the semiconductor chip can thus be impaired or disturbed. Another disadvantage of the semiconductor component is that the semiconductor chip must be masked and etched on the back side to produce the membrane, thus requiring an additional step.
SUMMARY OF THE INVENTION
Therefore, an object of the invention is to create a semiconductor component of the type described at the outset, avoiding any impairment of the additional function of the semiconductor component when a pressure acts on the pressure sensor. In addition, the semiconductor component should be inexpensive to manufacture.
This object is achieved in that the semiconductor chip is attached to the casing by an elastic carrier arrangement; the semiconductor chip on the whole can be deflected relative to the casing against the restoring force of the material of the carrier arrangement; and for indirect measurement of a pressure which acts on the semiconductor chip and produces a deflection, at least one position sensor that works together with the semiconductor chip is provided.
The semiconductor chip is thus deflected relative to the casing when pressure acts on it on the whole, thus preventing any change in its geometric dimensions. This avoids mechanical stress on the semiconductor chip and the development of bending stresses or tensile stresses and a related electric influence on the semiconductor structure provided for the additional function. Thus, the additional function can be executed with greater precision, while on the other hand the semiconductor component also has greater operational reliability, which permits its use in a larger temperature range, for example. Since this eliminates a membrane integrated into the semiconductor chip, it also results in a much smaller chip area, which permits inexpensive manufacture of the semiconductor chip. For example, the position sensor provided for indirect measurement of the pressure producing the deflection of the semiconductor chip may be an optical, inductive or magnetic sensor, preferably a non-contact sensor, which may optionally be integrated partially or completely into the semiconductor chip.
An especially advantageous embodiment of the invention provides for the position sensor to have a capacitor with at least two electrodes, one of which is a component of the semiconductor chip and the other is arranged on the casing. The capacitance of the capacitor is inversely proportional to the distance between the two electrodes. The deflection of the semiconductor chip depends on the spring characteristic of the carrier arrangement and may be in linear relationship to the pressure acting on the carrier arrangement and/or the semiconductor chip, for example. The capacitance is then inversely proportional to the pressure. The capacitive position measurement permits an especially simple design of the semiconductor component, where one of the capacitor electrodes may be formed by an electrically conducting area of the casing, for example, and the other capacitor electrode may be formed by an electrically conducting layer on the semiconductor chip and/or by the substrate of the semiconductor.
It is advantageous if the carrier arrangement has printed electric conductors for connecting terminal contacts arranged on the casing to terminal points on the semiconductor chip. The power supply voltage for the semiconductor chip, electric control signals and/or measurement signals can be transmitted easily between the semiconductor chip and the terminal contacts on the casing. The conductors may be printed on the carrier arrangement, for example, permitting inexpensive manufacture of the carrier arrangement. The capacitor electrode on the casing may optionally also be connected to the structure on the semiconductor chip, which may include a control and/or analysis device, by one of the printed conductors.
An especially advantageous embodiment of this invention provides for the printed conductors to be connected to the terminal points of the semiconductor chip and/or the terminal contacts of the casing by means of flip-chip technology. Bumps may be provided for electric contacting at the terminal points on the semiconductor chip and/or the printed conductors of the carrier arrangement. They may be soldered to mating contacts provided for them, for example, or connected by some other means. At the connecting points designed in the flip-chip technology, a plastic compound with conductive particles embedded in it may also be arranged between the printed conductors and the terminal points on the semiconductor chip or the terminal contacts of the casing, providing an electric connection between the printed conductors and the terminal points or terminal contacts. Bond wires between contact points to be joined can be eliminated by the flip-chip technology, thus greatly simplifying assembly of the semiconductor component.
A preferred embodiment of this invention provides for the carrier arrangement to have at least one substrate that carries the semiconductor chip and is elastically flexible against the restoring force of its material, for the substrate to be designed preferably as a bridge, with opposite end areas acting on the casing, and for the semiconductor chip to be fixedly connected to the substrate in the course between these two end areas. This yields a largely symmetrical carrier arrangement, which causes an approximately parallel displacement of the semiconductor chip and any capacitor electrode arranged on it, when acted upon by the pressure to be measured.
One embodiment of this invention provides for the substrate to be a film, in particular a plastic film. This may be made, for example, of polyimide, polyethylene or polyvinyl chloride. The film is applied to the casing, preferably on its peripheral edge, and is clamped there. The substrate is preferably arranged in the middle between opposite edge areas of the film acting on the casing, where
Akin Gump Strauss Hauer & Feld L.L.P.
Micronas GmbH
Wilson Allan R.
LandOfFree
Semiconductor component does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Semiconductor component, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Semiconductor component will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2879609