Semiconductor device manufacturing: process – Making passive device – Resistor
Reexamination Certificate
1992-01-03
2001-09-11
Dang, Trung (Department: 2823)
Semiconductor device manufacturing: process
Making passive device
Resistor
C438S381000, C438S384000
Reexamination Certificate
active
06287933
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a semiconductor device having a thin film resistor integrated therein and a method of producing the same as a molded resin package.
2. Description of the Related Art
Conventionally, a thin film resistor is formed and integrated with an insulating component of an IC, LSI or the like, to be used as a resistor.
This thin film resistor is usually composed of chromium (Cr) and silicon (Si) because the temperature coefficient of the resistance (TCR) thereof is low, and therefore any variations of the resistance due to changes in the temperature thereof are small.
Also, the TCR of this kind of thin film resistor composed of Cr and Si can be further lowered by varying the ratio of the content of Cr and Si.
Nevertheless, this kind of thin film resistor has a disadvantage in that it is difficult to make the TCR zero, and in general, preferably the value of &Dgr;R/R
25
, as shown in
FIG. 7
, is always zero even when the temperature is varied.
FIG. 7
shows the temperature dependency of the resistor value, and for the above purpose, a condition of a &agr;=0 and &bgr;=0 is required in the following equation obtained by the method of least squares.
&Dgr;R/R
25
=&agr;(
T−
25)+&bgr;(
T−
25)
2
Wherein R
25
represents a resistance value at a temperature of 25° C., &Dgr;R represents a variation of the value (R
T
−R
25
) of the resistance measured at the temperature T and R
25
, &agr; represents a primary coefficient, and &bgr; represents a secondary coefficient.
As shown in
FIG. 8
, a problem arises in that the condition of &agr;=0 can be realized but another condition, i.e., &bgr;=0 cannot be simultaneously realized.
It is considered that the reason for the non-linearity of the graph shown in
FIG. 7
is that, when the mobility &mgr; becomes greater due to the existence of the microcrystal of the CrSi
2
in the thin film resistor composed of a Cr—Si compound, the effect of the lattice vibration caused by the change in temperature becomes remarkable, and thus the resistance represented by the following equation will be varied because variation of the &mgr; becomes large as the temperature is raised.
Resistivity
=
1
q
×
μ
×
n
SUMMARY OF THE INVENTION
The present invention is intended to overcome the above problems and the object of this invention is to provide a semiconductor device having a thin film resistor, wherein little change of the value of the resistance occurs despite variations of the temperature thereof, and to provide a method of producing same.
Therefore, according to the present invention there is provided a semiconductor device having a thin film resistor composed of chromium, silicon and nitrogen, formed on a substrate, the device being characterized in that the thin film resistor is amorphous and has the same energy band structure as that of metal.
Alternatively, the thin film resistor of the semiconductor device of the present invention is composed of chromium, silicon, nitrogen and oxygen, and is formed on a substrate, and is further characterized in that the thin film resistor has a chemical composition ratio (a ratio of the atomic number) of Cr=1, Si=2-2.5, N=0.3-1.5 and O=0.5-1.5.
In accordance with the present invention there is also provided a method of producing the above semiconductor device having a thin film resistor composed chromium, silicon and nitrogen formed on a substrate and characterized in that the thin film resistor forming process comprises the steps of preparing a target containing at least chromium and silicon, the weight percentage of the silicon to the total weight of the chromium and silicon, being 41 to 57 weight %, and carrying out a reactive sputtering of a substrate utilizing that target in an atmosphere of an inert gas containing 1-2% of nitrogen gas, and is further characterized in that a thermal history of said thin film resistor applied thereto, after the completion of the thin film resistor forming process and upto the completion of the final process thereof, is less than 500° C.
In this process, the target may also include nitrogen.
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Wolf et al., “Silicon processing for the VLSI Era, vol. 1, Process Technology.”, Lattice Press, 1986, pp. 331-335.*
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Ban Hiroyuki
Iida Makio
Isobe Yoshihiko
Miura Shoji
Oda Katsuyoshi
Dang Trung
Nippondenso Co. Ltd.
Pillsbury & Winthrop
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