Semiconductor device manufacturing: process – Forming bipolar transistor by formation or alteration of... – Having heterojunction
Reexamination Certificate
2000-07-19
2002-06-11
Niebling, John F. (Department: 2813)
Semiconductor device manufacturing: process
Forming bipolar transistor by formation or alteration of...
Having heterojunction
C438S314000, C438S322000, C438S330000, C257S565000, C257S198000, C257S562000
Reexamination Certificate
active
06403436
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor device and a method of manufacturing the same and, more particularly, to a semiconductor device having an integral built-in bipolar transistor and resistor, and a method of manufacturing the same.
A transistor and resistor are integrally built into some semiconductor device by using a wafer epitaxially grown on a substrate. An example of a transistor used in a semiconductor device of this type includes a heterojunction bipolar transistor (to be referred to as an HBT hereinafter) or any other types of bipolar transistor.
In the semiconductor device described above having the integral built-in HBT and resistor, for example, as shown in
FIG. 11
, a subcollector layer
301
is epitaxially grown on an insulating semiconductor substrate
300
made of GaAs, a collector layer
302
, base layer
303
, and emitter layer
304
are sequentially epitaxially grown on the subcollector layer
301
, and a collector electrode
305
, base electrode
306
, and emitter electrode
307
are respectively formed on the subcollector layer
301
, the base layer
303
, and an emitter cap layer
308
on the emitter layer
304
, respectively. With this arrangement, a heterojunction bipolar transistor (HBT) device
310
is formed on the semiconductor substrate
300
.
In the semiconductor device shown in
FIG. 11
, an interlevel insulating film
311
is formed on the HBT device
310
described above, a metal resistor
313
is formed on the interlevel insulating film
311
, and a pair of metal resistor electrodes
312
are formed on the metal resistor
313
. In this manner, the HBT and resistor are integrally built into the semiconductor device.
In the semiconductor device having the arrangement shown in
FIG. 11
, since the interlevel insulating film
311
is arranged between the metal resistor
313
and subcollector layer
301
, it serves as a capacitance component. The resistance of the metal resistor
313
is thus influenced by the capacitance component, and a net resistance cannot be obtained. Also, an extra manufacturing process is necessary for forming the metal resistor
313
.
In a semiconductor device shown in
FIG. 12
having a built-in HBT device, a subcollector layer
301
b
is formed adjacent to a subcollector layer
301
that forms an HBT, a resistor is formed by using the subcollector layer
301
b,
and a pair of metal resistor electrodes
312
are formed on this resistor
301
b
. Implantation regions
309
are formed for element isolation.
In the semiconductor device shown in
FIG. 12
, since the subcollector layer
301
b
is used as an access layer between the subcollector layer
301
and the HBT device, its resistance must be as low as possible, and accordingly the sheet resistance cannot be increased. When a high-resistance resistor is to be formed, the area of the subcollector layer
301
b
used as the resistor undesirably increases.
In a semiconductor device shown in
FIG. 13
, while a subcollector layer
301
, collector layer
302
, and base layer
303
that form an HBT are epitaxially grown, a subcollector layer
301
b
, collector layer
302
b
, and base layer
303
b
are formed by epitaxial growth. The base layer
303
b
located at the uppermost position of the HBT is used as a resistor, and a pair of resistor electrodes
312
are formed on this resistor
303
b
. Implantation regions
309
are formed for element isolation in the same manner as in FIG.
12
.
In the semiconductor device shown in
FIG. 13
, when the collector layer
302
b
with a high resistance is used as a resistor, since the heavily doped collector layer
302
b
exists under the base layer
303
b
, the resistor comprised of the base layer
303
b
undesirably includes a capacitance component. Furthermore, since the base layer
303
b
has a thickness of as very small as 1,000 Å or less, the resistance of the resistor
303
b
varies.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a semiconductor device in which a resistor with a desired resistance can be integrally built together with an HBT device without adversely affecting the characteristics of the HBT device, and a method of manufacturing the same.
In order to achieve the above object, according to an aspect of the present invention, there is provided a semiconductor device having an integral built-in bipolar transistor and resistor, the bipolar transistor being obtained by sequentially forming a subcollector layer, a collector layer, a base layer, and an emitter layer on an insulating semiconductor substrate, wherein the subcollector layer of the bipolar transistor is formed of two subcollector layers with different thicknesses, a resistor layer is formed at the same level as, among the subcollector layers, one layer away from the collector layer, from the same material as that of the subcollector away from the collector layer, and the resistor layer forms the resistor.
REFERENCES:
patent: 6043520 (2000-03-01), Yamamoto et al.
NEC Corporation
Niebling John F.
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