Active solid-state devices (e.g. – transistors – solid-state diode – Field effect device – Having insulated electrode
Reexamination Certificate
2002-02-08
2004-10-05
Flynn, Nathan J. (Department: 2826)
Active solid-state devices (e.g., transistors, solid-state diode
Field effect device
Having insulated electrode
C257S335000, C257S351000, C257S368000, C257S288000, C438S197000, C216S027000
Reexamination Certificate
active
06800902
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device including transistors that are called an insulated gate transistor, a MIS (metal insulator semiconductor) field effect transistor or an MOS transistor, and more particularly to a semiconductor device that can be suitably mounted on an ink jet printer used as an output terminal such as a copying machine, a facsimile machine, a word processor or a computer, or on a liquid jet apparatus for manufacturing a DNA chip or an organic TFT, a method of manufacturing the same, and a liquid jet apparatus.
2. Related Background Art
Now, an example of a semiconductor device used in the liquid jet apparatus will be described.
In a recording apparatus used as various output terminals, an electro-thermal converter, an element that switches the electro-thermal converter element (hereinafter referred to as “switching element”), and a circuit for driving the switching element are mounted on a common substrate as a recording head.
FIG. 19
is a schematic cross-sectional view showing a part of a recording head according to a conventional structure.
Reference numeral
901
denotes a semiconductor substrate made of single crystal silicon. Reference numeral
912
is a p-type well region,
908
is an n-type drain region having a high impurity concentration,
916
is an n-type field relaxation drain region having a low impurity concentration,
907
is an n-type source region having a high impurity concentration, and
914
is a gate electrode. These elements form a switching element
930
using a MIS field effect transistor. Reference numeral
917
denotes a regenerative layer and a silicon oxide layer that functions as an insulating layer,
918
is a tantalum nitride film that functions as a heat resistant layer,
919
is an aluminum alloy film that functions as a wiring, and
920
is a silicon nitride film that functions as a protective layer. These elements form a substrate
940
of the recording head. In this example, reference numeral
950
denotes a heating portion, and an ink is jetted from
960
. Also, a roof
970
defines a liquid passage
980
in cooperation with the substrate
940
.
Incidentally, improvements have been frequently made to the recording head and the switching element structured as described above. In recent years, demands have been further made to increase a drive speed, to save an energy, to increase integration, to reduce the costs and to enhance the performance, with respect to such products.
A plurality of MIS field effect transistors
930
used as the switching elements shown in
FIG. 19
are produced within the semiconductor substrate
901
. And these MIS field effect transistors
930
are operated independently or at the same time to drive the connected electro-thermal converter.
However, when the conventional MIS field effect transistor
930
functions under the condition where a large current required to drive a load such as the electro-thermal converter flows, a pn reverse bias junction portion between a drain and a well generates a leak current since it cannot withstand a high electric field, and therefore it cannot satisfy a breakdown voltage required as a switching element. In addition, when the on resistance of the MIS field effect transistor used as the switching element is large, there arises such a problem to be solved that a current necessary to drive the electro-thermal converter cannot be obtained by resulting wasteful current consumption.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above circumstances, and therefore an object of the present invention is to provide a high-performance semiconductor device including an insulated gate transistor, which allows a large current to flow, and enables high-speed drive at a high breakdown voltage, energy saving and high integration.
Another object of the present invention is to provide a liquid jet apparatus which allows a large current to flow, and enables high-speed drive at a high breakdown voltage, energy saving and high integration.
Still another object of the present invention is to provide a method of manufacturing a high-performance semiconductor device which can achieve higher integration and reduced costs.
According to an aspect of the present invention, there is provided a semiconductor device in which a switching element for allowing a current to flow in a load and a circuit for driving the switching element are formed on a common substrate, characterized in that:
the switching element is a first insulated gate transistor which comprises:
a first semiconductor region of a second conductive type disposed at one main surface of a semiconductor substrate of a first conductive type;
a second semiconductor region of the first conductive type disposed within the first semiconductor region;
a first gate electrode disposed on a surface at which a pn junction between the second semiconductor region and the first semiconductor region terminates through an insulating film;
a first source region of the second conductive type disposed on one end portion side of the first gate electrode within the second semiconductor region; and
a first drain region of the second conductive type disposed within the first semiconductor region; and that
the circuit for driving the switching element comprises a second insulated gate transistor having a characteristic different from the first insulated gate transistor.
Here, the second insulated gate transistor preferably constitutes a level shift circuit that generates a drive voltage applied to the first gate electrode.
The drain region of the second insulated gate transistor preferably includes a low impurity concentration region.
It is preferable that the second insulated gate transistor constitute a level shift circuit that generates a drive voltage applied to the first gate, and that a low impurity concentration region be disposed within a drain region of the second insulated gate transistor.
The second insulated gate transistor preferably comprises a source follower transistor that constitutes a level shift circuit that generates a drive voltage applied to the first gate through a CMOS circuit.
A well potential of the second insulated gate transistor is preferably different from both a source potential and a drain potential.
A drain region of the second insulated gate transistor preferably has a low impurity concentration region that is formed to be shallower than the first semiconductor region.
A drain region of the second insulated gate transistor preferably has a low impurity concentration region having the same depth as that of the first semiconductor region.
The second semiconductor region is preferably formed to be deeper than the first semiconductor region.
A plurality of first insulated gate transistors are preferably arranged in an array, without dedicated element isolation regions being interposed therebetween.
The second insulated gate transistor is preferably an MOS transistor of the first conductive type which constitutes a low-voltage CMOS circuit.
It is preferable that the circuit for driving the switching element comprises a low-voltage CMOS circuit having the second insulated gate transistor, and a high-voltage CMOS circuit that is controlled by the low-voltage CMOS circuit, and that an MOS transistor of the first conductive type which constitutes the high-voltage CMOS circuit is a DMOS transistor produced in the same process as that for forming the first insulated gate transistor.
It is preferable that the semiconductor device of the present invention further comprise a level shift circuit that generates a drive voltage applied to the first gate electrode through the high-voltage CMOS circuit.
The second insulated gate transistor preferably includes source and drain regions of the first conductive type which are formed within the well of the second conductive type.
An electro-thermal converter that functions as the load is preferably connected to a drain of the switching element and is integrated.
The characteristic described
Flynn Nathan J.
Mandala Jr. Victor A.
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