Semiconductor device manufacturing: process – Making passive device – Resistor
Reexamination Certificate
2000-04-26
2001-10-23
Tsai, Jey (Department: 2812)
Semiconductor device manufacturing: process
Making passive device
Resistor
C438S238000, C438S385000
Reexamination Certificate
active
06306718
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to an improved polysilicon resistor and method for making the same.
2. Description of the Related Art
Various types of polysilicon resistors have been known. However in making polysilicon resistors in the past several problems and deficiencies have been noted. Specifically a trimming of the resistance value either by lasers or by having multiple resistors and having to “blow” links have been needed to obtain high accuracy in the resistance value. Further the resistors that are formed have first and second order temperature coefficients (TC1 and TC2) in normal operation ranges that make them less than ideal.
Other attempts at other non-laser trimmed resistor such as Isobe, et al. U.S. Pat. No. 5,187,559 and Amemiya et al., U.S. Pat. No. 4,210,996 have been tried. However these also suffer from various problems as to the temperature coefficients and the methods of making them are difficult. As an example although the Amemiya et al. device allows for electrical trimming however the temperature characteristics do not lend themselves to ready usage. Further a device built along the lines Amemiya et al. can only be built using doping concentrations at higher than 1×10
20
atoms/cm
3
. Consequently this device is less than desirable.
A device according to Isobe, et al. actually requires that two dopings occur for each resistor one with a positive TC1 and a second with a negative TC1 be used so that a zero TC1 resistor can be formed. This increases the complexity of formation of the device. Further both dopings are at high levels of concentrations, which create problems in the manufacturing process .
SUMMARY OF THE INVENTION
The present invention overcomes the shortcomings and deficiencies noted above by providing a new electrically trimmed polysilicon resistor that can be electrically trimmed by controlling the grain boundary resistance by the movement of the impurity doping. The second order temperature coefficient can also be altered in predictable manners. The trimming range of the resistor itself also can be adjusted over a very wide range.
By having an electrically trimmed resistor of this type various types of improved and new devices can be built that have not been possible, heretofore.
The improvement provided in the accuracy of the resistors can make termination devices such as SCSI terminators with fewer and more accurate resistors, making the SCSI terminators cheaper and/or more accurate.
Improved temperature sensors are also possible. As the temperature coefficients and the resistance of one or more resistors can be independently adjusted an improved differential temperature sensor could be built. This independent adjustment can also make an improved zero temperature coefficient resistor possible that has adjustable temperature characteristics, by using two resistors and trimming them so that they have temperature coefficients of opposite signs.
The ability to adjust first and second order temperature coefficients also allows for improved second order fits of resistors or with more linear temperature characteristics. It should be noted that TC2 as will be discussed below decreases considerably with electrical trimming at various doping concentrations (see for example FIG.
6
).
Other possibilities include improved anemometers and bolometers with increased sensitivity.
Also as this “trimming” can be controlled by an electrical circuit the resistor can be used as a permanent indicator of events such as ESD event or it can act as a type of electrical fuse based upon a programmed change in a resistors characteristics.
The trimmed resistor can also be used to improved bandgap circuits, A/D and D/A converters. OP-amp offsets, digital potentiometers and delay lines can likewise be improved. Also digital thermometers, oscillators and filters can also benefit from this type of resistor.
As another example an electrically trimmed resistor could act as a multi-bit analog memory by employing multiple trimmed values of one or more of these resistors.
REFERENCES:
patent: 4210996 (1980-07-01), Amemiya et al.
patent: 5187559 (1993-02-01), Isobe et al.
patent: 5854103 (1998-12-01), Liang
patent: 6204105 (2001-03-01), Jung
“Electrical Trimming of Heavily Doped Polycrystalline Silicon Resistors”, by Yoshihito Amemiya, Terukazu Ono and Kotaro Kato, IEEE Transactions on Electron Devices, vol. ED-26, No. 11, Nov. 1979.
“A Physical Mechanism of Current-Induced Resistance Decrease in Heavily Doped Polysilicon Resistors”, by Kotaro Kato, Terukazu Ono, and Yoshihito Amemiya, IEEE Transactions on Electron Devices, vol. ED-29, No. 8, Aug. 1982.
“A Monolithic 14 Bit D/A Converter Fabricated with a New Trimming Technique (DOT)”, by Kotaro Kato, Terukazu Ono, and Yoshihito Amemiya, IEEE Journal of Solid-State Circuits, vol. SC-19, No. 5, Oct. 1984.
“Polysilicon Resistor Trimming for Packaged Integrated Circuits”, by J.A. Babcock, D.W. Feldbaumer, and V.M. Mercier, IEEE, 1993.
“Electrical Trimming of Ion-Beam-Sputtered Polysilicon Resistors by High Current Pulses”, by Soumen Das and Samir K. Lahiri, IEEE Transactions on Electron Devices, vol. 41, No. 8, Aug. 1994.
“Constant Voltage Trimming of Heavily Doped Polysilicon Resistors”, by Kotaro Kato and Terukazu Ono, Jpn. J. Appl. Phys. vol 34, pp. 48-53, Jan. 1995.
“Theory and Application of Polysilicon Resistor Trimming”, by D.W. Feldbaumer and J.A. Babcock, Solid-State Electronics vol. 38, No. 11, pp. 1861-1869, 1995.
“Pulse Current Trimming of Polysilicon Resistors”, by David W. Feldbaumer, Jeffrey A. Babcock, Vickie M. Mercier, and Christopher K.Y. Chun, IEEE Transactions on Electron Devices, vol. 42, No. 4, Apr. 1995.
“Change in Temperature Coefficient of Resistance of Heavily Doped Polysilicon Resistors Caused by Electrical Trimming”, by Kotaro Kato and Terukazu Ono, Jpn. J. Appl. Phys. vol. 35, pp. 4209-4215, Aug. 1996.
“Polycrystalline Silicon for Integrated Circuits and Displays Second Edition”, by Ted Kamins, p.266, 1998.
Harrington, III Thomas E.
Hensley Roy Austin
Kumar Tanmay
Mitchell Allan T.
Qian Jack Gang
Dallas Semiconductor Corporation
Tsai Jey
LandOfFree
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