Electrical resistors – Resistance value responsive to a condition – Fluid- or gas pressure-actuated
Reexamination Certificate
1998-06-11
2001-03-06
Easthom, Karl D. (Department: 2832)
Electrical resistors
Resistance value responsive to a condition
Fluid- or gas pressure-actuated
C257S419000, C073S721000, C073S727000
Reexamination Certificate
active
06198379
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a circuit arrangement implemented as an integrated semiconductor component.
BACKGROUND INFORMATION
It is known that an integrated semiconductor component can be designed as a component for a weight determination, where piezoresistive measuring shunts are connected to a membrane acted on by a mass to be weighed. There is no direct contact of the diffused measuring shunts with metallic terminal contacts to connect the measuring shunts to an analysis circuit to avoid effects on the measuring shunts due to different temperature coefficients of metal and semiconductor substrate. For this purpose, in a conventional semiconductor component, the measuring shunts are not connected directly to the metallic terminals but instead are connected to the metallic terminals across terminal resistors. The terminal resistors are formed with a negligible piezoresistive sensitivity. Thus, the terminal resistors may include a low-resistance diffusion level, which is superimposed on another diffusion level, usually the diffusion level of the measuring shunts. Although the piezoresistive measuring shunts can be adequately isolated from the metallic terminal contacts with respect to thermal effects using such terminal resistors, these terminal resistors result in additional problems because of their close proximity and connection to the measuring shunts. These problems include offset errors, because the terminal resistors have a different size and shape. Furthermore, there is the risk of bypass connections between adjacent terminal resistors, because these adjacent terminal resistors usually extend parallel to one another over a relatively great distance starting from their connection to the measuring shunts. Furthermore, an offset between the diffusion levels of the measuring shunts and the terminal resistors leads to additional offset errors of the measuring bridge. In addition, it is not always guaranteed that the terminal resistors can be designed to have a sufficiently low resistance so as not to impair the sensitivity of the measuring bridge.
SUMMARY OF THE INVENTION
The circuit arrangement according to the present invention is advantageous in that the terminal resistors are formed identically and have a predetermined shape. The terminal resistors have a predetermined minimum mutual spacing therebetween to prevent bypass connections from developing in parallel to the measuring shunts, despite the paired arrangement in direct proximity owing to their contact with the measuring shunts. Offset errors on the respective measuring shunt over the terminal resistors are prevented due to their identical shape and size. Because of their special shape, the terminal resistors may be alternately arranged with no problem in parallel or perpendicularly to one another on a measuring shunt, with the result being achieved in any position of the terminal resistors on a measuring shunt that a vertical offset between the diffusion level of the measuring shunts and the diffusion level of the terminal resistors results in a change in the terminal conditions in a similar manner, so that the absolute values of the individual resistors in each half bridge of the measuring shunts which are combined to form a measuring bridge change in the same sense. Thus, there is no offset error in the measuring bridge. The same ratiolization applies for a horizontal offset of these diffusion levels which influences all the bridge resistors equally, so that no offset error occurs in this case either.
According to another embodiment of the circuit arrangement according to the present invention, each terminal contact includes three contiguous area elements (e.g., a large-area base body in relation to the other area elements for connection to a metallic terminal element) and a head for connection to a measuring shunt. The head has a very small-area in relation to the base body, and has rotational or mirror symmetry within itself. The head is arranged with a lateral offset to said base body, and a neck connecting the base body to the head and widening, preferably continuously, from the small-area head to the large-area base body. The metallic terminal element is arranged in or on a location on the base body which is at a maximum distance from said head. The symmetrical design of the head ensures that the terminal conditions for the respective measuring shunt are almost identical, regardless of its location. This eliminates offset errors due to the terminal. The continuous widening of the neck starting from the head of the terminal resistor to its base body results in a low overall resistance value. The lateral offset arrangement of the head with respect to the base body and the resulting inclined arrangement of the neck achieves the result that, regardless of the position of the measuring shunt within the circuit arrangement, provides a minimum distance between adjacent terminal resistors of a measuring shunt only for a short distance and the distance increases again as soon as possible, which prevents bypass connections.
The elongated basic shape of the uniformly designed terminal resistor according to the present invention and the position of the contacts relative to the measuring shunt or to the terminal contact results in a large distance between the measuring shunt and the terminal contact which is almost position-independent.
The base body is designed to be rectangular and one of its narrow sides develops into the neck. The rectangular shape ensures problem-free manufacturing of the base body, and the orientation of the rectangle with the narrow side connecting to the neck then guarantees a maximum distance between the terminal contact and the measuring shunt.
The neck generally has a predetermined curvature to ensure a minimum distance between neighboring terminal resistors and the same measuring shunt regardless of their position. The curved shape of the neck can also be approximated by appropriate trapezoidal sections.
The resistor head is designed with a square shape, with the corners of the square preferably being chamfered for connection of a measuring shunt. Alternatively, the resistor head may also be designed as a rectangle, which is different from the square shape, and the corner chamfer may also be omitted so as to not to result in any position-dependent terminal conditions for the measuring shunt due to process-specific diffusion behavior.
The terminal resistors are advantageously covered with a cover layer having a doping corresponding to a doping of the respective measuring shunt.
REFERENCES:
patent: 3341794 (1967-09-01), Stedman
patent: 3537319 (1970-11-01), Yerman
patent: 3918019 (1975-11-01), Nunn
patent: 4439752 (1984-03-01), Starr
patent: 4530244 (1985-07-01), Starr
patent: 5170237 (1992-12-01), Tsuda et al.
patent: 5349867 (1994-09-01), Park
patent: 5412993 (1995-05-01), Ohtani
patent: 5537882 (1996-07-01), Ugai et al.
patent: 5812047 (1998-09-01), van Kampen
Easthom Karl D.
Kenyon & Kenyon
Robert & Bosch GmbH
LandOfFree
Semiconductor component with piezoresistive measuring shunts 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 with piezoresistive measuring shunts, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Semiconductor component with piezoresistive measuring shunts will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2547758