Active solid-state devices (e.g. – transistors – solid-state diode – Heterojunction device – Light responsive structure
Reexamination Certificate
1998-06-26
2001-06-26
Jackson, Jr., Jerome (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Heterojunction device
Light responsive structure
C257S449000, C257S452000, C257S459000, C257S457000
Reexamination Certificate
active
06252260
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates in general to an electrode structure of an infrared detector, and more particularly, to an electrode structure of a hetero-junction internal photo-emission (HIP) infrared detector.
2. Description of the Related Art
As the development of military science and radiotelemetry technique become more and more advanced, the application by employing an infrared focal array (FPA) is more and more important. An intensive research has been directed towards the infrared detector with a wavelength of about 8 &mgr;m to 14 &mgr;m due to its high sensitivity against the object temperature nearby.
In Appl. Phys. Lett., 1990, 57(14), T. L. Lin and J. Maserjian have disclosed a p
+-Ge
x
Si
1−x
/p-Si HIP infrared detector as shown in FIG.
1
. The detector comprises a p-type silicon substrate
100
. In the p-type substrate
100
, a p
+
contact
102
for Ohmic contact and an n
+
guard ring
104
are formed. A silicon oxide layer
106
is formed and defined on the p-type silicon substrate
100
. As shown in the figure, a central part of the p
+
contact
102
, an inner part of the guard ring
104
, and a region
108
of the p
+
silicon substrate
100
which is encompassed by the guard ring
104
are exposed. A p
+
-Ge
x
Si
1−x
/p-Si layer
110
is formed on the exposed guard ring
104
and the exposed p
+
silicon substrate
100
. An aluminum layer is formed and defined. Therefore, an aluminum (Al) electrode
112
a
covers the exposed p
+
contact
102
and a part of the silicon oxide layer
106
. Another Al electrode
112
b
is formed on a part of the p
+
-Ge
x
Si
1−x
/p-Si layer
110
at a region aligned over the silicon oxide layer
106
.
In the above structure, since the aluminum electrode
112
b
does not directly contact with the silicon substrate
100
, therefore, the spike effect between aluminum and silicon is avoided. As a consequence, the leakage current is reduced and suppressed. However, there are two drawbacks of the structure:
1) The thickness of the Ge
x
Si
1−x
layer is as thin as about 100 nm, so that the silicon oxide layer
106
as an insulation has to be as thin as possible to avoid the Ge
x
Si
1−x
layer to break in the step region. However, considering the dielectric property, the silicon oxide layer has to maintain a certain thickness. Furthermore, while cleaning the Ge
x
Si
1−x
layer during patterning, a part of the silicon oxide layer is removed by the cleaning solution, for example, HF. Therefore, a very high manufacturing cost is required to control the thickness of the silicon oxide layer during cleaning process for the Ge
x
Si
1−x
layer and growing process of silicon oxide layer.
2) The region of the Ge
x
Si
1−x
layer over the silicon oxide layer is in an amorphous state. Therefore, a poor conductivity is obtained, and a parasitic resistance is formed to affect the performance of the device.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide an electrode structure of an HIP infrared detector. In the detector, the electrode electrically connects the silicon substrate through a single crystalline photosensitive alloy. Therefore, the conductivity is improved. Furthermore, by forming an electrode on the photosensitive alloy layer aligned with the guard ring, without forming the electrode over the silicon substrate, the spike effect between the electrode and the silicon substrate is prevented.
To achieve these objects and advantages, and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention is directed towards an electrode structure of an HIP infrared detector. A HIP infrared comprises a p-type silicon substrate which has an exposed guard ring, an exposed region of the silicon substrate encompassed by the guard ring, and a silicon oxide layer covering a part of the guard ring and the silicon substrate. On the silicon substrate, a photosensitive alloy layer comprises an amorphous photosensitive alloy layer on the silicon oxide layer, and a single crystalline photosensitive alloy layer on both the part of the silicon substrate encompassed by the guard ring and the guard ring. An electrode electrically connects the silicon substrate via the photosensitive alloy layer. Moreover, the HIP infrared further comprises a p
+
Ohmic contact in the silicon substrate and another electrode to contact with the p
+
Ohmic contact.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
REFERENCES:
patent: 4544939 (1985-10-01), Kosonochy
patent: 5163179 (1992-11-01), Pellegrini
Chen Peiyi
Qian Peixin
Wang Ruizhong
Jackson, Jr. Jerome
United Microelectronics Corp.
LandOfFree
Electrode structure of hetero-junction intertal... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electrode structure of hetero-junction intertal..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electrode structure of hetero-junction intertal... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2535180