Semiconductor device

Details Semiconductor device Semiconductor device

2002-12-23

2004-07-27

Ngô, Ngân V. (Department: 2814)

Active solid-state devices (e.g., transistors, solid-state diode

Field effect device

Having insulated electrode

C257S296000, C257S307000, C257S533000

Reexamination Certificate

active

06768153

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device, and more specifically to a semiconductor device comprising metal-insulator-metal (MIM) capacitor.
2. Description of the Related Art
In semiconductor devices used in communication equipment or cellular phones using microwaves, transistors that use compound semiconductors as elements for low noise amplifiers suited to radio-frequency operation are used for down-sizing and performance improvement of semiconductor devices.
In such semiconductor devices, for example, multistage amplifiers, transistors are used as elements for amplifiers, and DC power is supplied thereto. In order that the source of such DC power does not adversely affect the RF properties of elements for amplifiers, capacitors are connected to DC power terminals; and in order to isolate DC power between amplifier stages, capacitors are connected between stages.
FIG. 30
is a circuit diagram of a conventional amplifier.
In
FIG. 30
, reference numeral
200
denotes the amplifier shown here by the circuit diagram. Reference numerals
202
and
204
denote field effect transistors (hereafter abbreviated as FETs), and reference numerals
206
and
208
denote grounding ends. The source terminals of the FETs
202
and
204
are grounded by the grounding ends
206
and
208
, respectively.
Reference numerals
210
,
212
,
214
, and
216
denote DC electrodes.
DC power is supplied to the gate terminal of the FET
202
from the DC electrode
210
; to the drain terminal of the FET
202
from the DC electrode
212
; to the gate terminal of the FET
204
from the DC electrode
214
; and to the drain terminal of the FET
202
from the DC electrode
216
. Reference numerals
218
,
220
,
222
,
224
, and
226
denote capacitors used in this amplifier.
Reference numerals
228
,
230
,
232
, and
234
denote the paths of electric current flowing in the FETs
202
and
204
. The path
228
is the path of the gate current of the FET
202
, the path
230
is the path of the drain current of the FET
202
, the path
232
is the path of the gate current of the FET
204
, and the path
234
is the path of the drain current of the FET
204
.
FIG. 31
is a plan showing a capacitor used in a conventional amplifier.
FIG. 32
is a sectional view of the capacitor shown in
FIG. 31
along the dashed line
32
—
32
.
Reference numeral
236
denotes an MIM capacitor. Such an MIM capacitor
236
is used as capacitors
218
,
220
,
222
,
224
, and
226
of the amplifier shown in FIG.
30
.
In
FIGS. 31 and 32
, reference numeral
238
denotes a circuit substrate,
240
denotes a wiring layer,
242
denotes a lower electrode,
244
denotes a dielectric layer,
246
denotes an upper electrode,
248
denotes a connecting conductor, and
250
denotes a back conductor.
The amplifier
200
is normally formed as an MMIC (monolithic microwave integrated circuit), and all of the circuit elements are constituted on a semiconductor chip. Therefore, the MIM capacitors
236
used as capacitors
218
,
220
,
222
,
224
, and
226
must also be tested not to be defective. This test must include a withstand voltage test normally using a DC voltage, and is conducted by grounding one terminal of the capacitor, and impressing a voltage to the other terminal.
In the amplifier
200
, the case is considered where a high voltage is impressed to the DC electrode
210
for conducting the withstand voltage test of the capacitor
218
. At this time, the capacitor
218
and the FET
202
are in such a relationship as they are connected in parallel between the DC electrode
210
and the grounding end.
FIG. 33
is a schematic diagram showing an equivalent circuit of a capacitor and a transistor in a conventional amplifier.
In
FIG. 33
, reference numeral
252
denotes a DC electrode, for example the DC electrode
210
. Reference numeral
254
denotes a capacitor, for example the capacitor
218
. Reference numeral
256
denotes a resistor element, for example, the resistor component of the FET
202
is equivalently shown. Reference numeral
258
denotes a current path.
When a voltage is impressed to the DC electrode
210
to conduct the withstand voltage test of the capacitor
218
, since the capacitor
218
and the FET
202
are connected in parallel relative to the grounding end, a current flows dominantly in the current path
258
as shown in the equivalent circuit of FIG.
33
. Therefore, even if one tries to impress a voltage required for the withstand voltage test of the capacitor
218
corresponding to the capacitor
254
, a large current flows in the FET
202
corresponding to the resistor element
256
, and the withstand voltage test of the capacitor
218
cannot be conducted.
The same situations occur also in capacitors
220
,
222
,
224
, and
226
. Therefore, a method must be used wherein the operation test of the amplifier
200
is conducted for a long time to check the occurrence of defective capacitors before shipping. Consequently, it takes a long time for the manufacturing process of amplifiers, and defective products may be detected in the final process, resulting in an increase in the costs of the amplifiers.
Japanese Patent Laid-Open No. Hei 9(1997)-74144, corresponding to U.S. Pat. No. 5,801,413 discloses a semiconductor device comprising capacitance elements having an excellent area efficiency by constituting capacitors of the same constitution as the memory cell capacitors in a DRAM memory, and describes that the capacitance elements are connected in series, and a pad is provided on the connecting point in the middle, which is used as the testing pad for testing defective insulating films. However, this prior technique does not use MIM capacitors, and the connecting relationship with transistors is also different.
SUMMARY OF THE INVENTION
The present invention has been devised to solve the above problems.
According to one aspect of the invention, there is provided a semiconductor device comprising: a substrate having a main surface, an MIM capacitor having a first electrode layer disposed on the main surface of the substrate, second and third electrode layers facing the first electrode layer through a dielectric layer; a terminal pad connected to the first electrode layer of the MIM capacitor; a first terminal connected to the second electrode layer of the MIM capacitor; a second terminal connected to the third electrode layer of the MIM capacitor; and a first active element whose first electrode is connected to the second electrode layer of the MIM capacitor.
Accordingly, the withstand voltage test of MIM capacitors can be conducted without damaging the first active element, defective products can be eliminated in the early stages of the process, and the yield of the final products can be improved. In its turn, semiconductor devices of a high reliability can be provided at low costs.
Other objects and advantages of the invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific embodiments are given by way of illustration only since various changes and modifications within the scope of the invention will become apparent to those skilled in the art from this detailed description.


REFERENCES:
patent: 5801412 (1998-09-01), Tobita
patent: 6495874 (2002-12-01), Kawamura et al.
patent: 2002/0063298 (2002-05-01), Wang
patent: 2003/0042521 (2003-03-01), Yoshitomi et al.

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