Active solid-state devices (e.g. – transistors – solid-state diode – Integrated circuit structure with electrically isolated... – Passive components in ics
Reexamination Certificate
1999-10-07
2002-01-22
Prenty, Mark V. (Department: 2822)
Active solid-state devices (e.g., transistors, solid-state diode
Integrated circuit structure with electrically isolated...
Passive components in ics
C257S904000
Reexamination Certificate
active
06340835
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to semiconductor processing methods of forming resistors and diodes from semiconductive material, and to static random access memory (SRAM) cells incorporating resistors, and to other integrated circuitry incorporating resistors and diodes.
BACKGROUND OF THE INVENTION
One of the common elements required in electrical circuit devices is the pull-up or pull-down resistor from an active device to one of the power supply buses, typically referred to as Vcc. The pull-up is simple if used to construct a circuit using discrete components in that all that is required is selecting a resistor of the desired resistance and tolerance, connecting it between an active device such as an open collector transistor and Vcc, and the transistor's output would be pulled up to Vcc once the transistor is forward biased. With the advent of integrated circuitry, however, fabricating a resistance onto a wafer substrate, such as silicon or gallium arsenide, takes special consideration, particularly when resistivity and tolerances play an important part in circuit operation.
For example, as SRAMs have evolved from the 4 Kb memory arrays to more densely packed array sizes, tolerances of pull-up resistances had to be tightly controlled. In order to minimize standby current, many fabrication processes adopted use an active device as the pull-up. In CMOS fabrcation, it is common to see a PMOS transistor acting as the current path between a memory cell access transistor and the power supply bus. In this manner, the PMOS transistor can be gated “on” only when the desired line is to be puffed up to Vcc and turned “off” otherwise. This in essence eliminates leakage current and minimizes standby current for the SRAM device as a whole.
The main drawback to using an active device for a pull-up device is the amount of space required to fabricate the device. Now that the SRAM generation has grown to the 1 Mb array size, die space is a critical factor to consider. Technology has basically pushed all types of integrated circuits to be more densely packed, and pull-ups are a common element in many circuit designs.
Although the invention primarily arose out of concerns associated with resistor fabrication in SRAM circuitry, the artisan will appreciate applicability of the inventive technology elsewhere, with the invention only being limited by the accompanying claims appropriately interpreted in accordance with the doctrine of equivalents.
REFERENCES:
patent: 4406051 (1983-09-01), Iizuka
patent: 4411708 (1983-10-01), Winhan
patent: 4702937 (1987-10-01), Yamoto et al.
patent: 4727045 (1988-02-01), Cheung et al.
patent: 4829024 (1989-05-01), Klein et al.
patent: 4933739 (1990-06-01), Harari
patent: 4968645 (1990-11-01), Baldi et al.
patent: 5066605 (1991-11-01), Kasper et al.
patent: 5159430 (1992-10-01), Manning et al.
patent: 5177030 (1993-01-01), Lee et al.
patent: 5187114 (1993-02-01), Chan et al.
patent: 5241206 (1993-08-01), Lee et al.
patent: 5398200 (1995-03-01), Mazure et al.
patent: 5474948 (1995-12-01), Yamazaki
patent: 5489796 (1996-02-01), Harward
patent: 5521401 (1996-05-01), Zamanian et al.
patent: 5536960 (1996-07-01), Hayashi
patent: 5567644 (1996-10-01), Rolfson et al.
patent: 5578854 (1996-11-01), Chen et al.
patent: 5589418 (1996-12-01), Kalnitsky
patent: 5602408 (1997-02-01), Watanabe et al.
patent: 5629240 (1997-05-01), Malladi et al.
patent: 5641991 (1997-06-01), Sakoh
patent: 5668037 (1997-09-01), Prall et al.
patent: 5683930 (1997-11-01), Batra et al.
patent: 5732023 (1998-03-01), Roberts
patent: 5770496 (1998-06-01), Roberts
patent: 5825074 (1998-10-01), Rolfson et al.
patent: 5831276 (1998-11-01), Gonzalez et al.
patent: 5867087 (1999-02-01), Wuu et al.
patent: 5892292 (1999-04-01), Easter
patent: 5930662 (1999-07-01), Manning
patent: 5998276 (1999-12-01), Batra et al.
patent: 6008082 (1999-12-01), Rolfson et al.
patent: 6043117 (2000-03-01), Batra et al.
patent: 63-141360 (1988-06-01), None
S. Wolf et al., “Silicon Processing for the VLSI Era”, vol. 1—Process Technology, 1986, pp. 137-138, 189-191.
Manning Monte
Rolfson J. Brett
Micro)n Technology, Inc.
Prenty Mark V.
Wells, St. John, Roberts Gregory & Matkin P.S.
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