Active solid-state devices (e.g. – transistors – solid-state diode – Combined with electrical contact or lead – Of specified material other than unalloyed aluminum
Reexamination Certificate
2000-05-18
2004-05-11
Kang, Donghee (Department: 2811)
Active solid-state devices (e.g., transistors, solid-state diode
Combined with electrical contact or lead
Of specified material other than unalloyed aluminum
C257S760000, C257S762000, C257S765000, C257S774000, C257S296000, C438S118000, C438S622000, C438S623000, C438S624000, C438S637000, C438S638000
Reexamination Certificate
active
06734561
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device and a method of producing the semiconductor device, in particular, to a semiconductor device having a contact structure utilizing a multi-layer conductive plug and a method of producing the semiconductor device.
2. Discussion of Background
In recent years, a size of a contact hole is reduced along with microminituarization of a semiconductor integrated circuit. As a result, it becomes difficult to form a resist pattern, and etching using this resist pattern as a mask becomes difficult by an increment of an aspect ratio of the contact hole.
In order to reduce the aspect ratio and a load in etching, there has been proposed a method of obtaining a contact structure by dividing an inter-layer insulating film into multi layers, forming a contact hole in each of the multi layers, and vertically connecting conductive plugs embedded in the contact holes.
However, according to these methods, misregistration between the horizontally arranged contact holes is apt to occur, an insulating film in a lower layer is etched at time of forming the contact hole in an insulating film in an upper layer by etching. Further, in a worse case, the contact hole in the upper layer reaches an electrode layer located in the insulating film in the lower layer, whereby an electric short is caused.
In order to solve such a problem, in Japanese Unexamined Patent Publication JP-A-8-37181, a contact structure, in which an etching prevention film is interposed between an insulating film in an upper layer and an insulating film in a lower layer, is disclosed.
In other words, in reference of a cross-sectional view in a step of a process illustrated in
FIG. 22
of the above JP-A-8-37181, even though an upper insulating film
108
is disposed on a lower insulating film
104
through an etching prevention film
105
, and succeedingly an upper layer contact hole
109
formed on the upper insulating film
108
is deviated from a lower contact hole
106
so that a part of the upper contact hole
109
reaches a lower layer insulating film
104
by etching, the lower layer insulating film
104
is not etched, whereby the upper layer contact hole
109
does not reach electrode layers
103
a
,
103
b
on a semiconductor substrate
101
.
However, in a conventional technique disclose in the above JP-A-8-37181, when a semiconductor device is further integrated and a size of a contact hole is further microminiaturized, a good contact hole cannot be formed because dimensional controllability and a shape of a resist pattern, which is formed on an etching prevention film, are deteriorated. Therefore, there are problems that a dimensional accuracy and a shape of a conductive plug formed in the contact hole are deteriorated, and a stable electrical connection between upper and lower conductive plugs is not obtainable.
Incidentally, in the above JP-A-8-37181, a method of forming the etching prevention film after forming the conductive plug is disclosed. According to such a process, it is possible to prevent the etching prevention film from thinning at time of forming the conductive plug by etching.
In other words, in reference of a cross-sectional view explaining a step of a process of manufacturing the semiconductor device, after forming the lower layer insulating film
104
including a conductive plug
107
formed in the lower layer contact hole
106
, an etching prevention film
124
is formed, and further an insulating film
108
including an upper layer contact hole
109
is formed on the etching prevention film
124
. The etching prevention film
124
prevents etching to the lower layer insulating film
104
when the upper layer contact hole
109
is formed with a deviation from the lower layer contact hole
106
. Thereafter, as illustrated in FIG.
23
(
b
), the etching prevention film
124
exposed inside the upper layer contact hole
109
is etched so as to be connected to the lower layer film conductive plug
107
. Thereafter, an upper layer conductive plug
110
is embedded in an upper layer contact hole
109
so as to be connected to the lower layer conductive plug
107
.
However, in such a method of forming, as illustrated in FIG.
24
(
a
), a problem occurs when a surface of the lower layer conductive plug
107
is formed with a large drop
172
with respect to a surface of the lower layer insulating film
104
. Namely, the etching prevention film
124
has an uneven shape reflecting a shape of the drop. When the upper layer insulating film
108
and upper layer contact hole
109
connected to the conductive plug
107
are formed, there are problems that a part of the etching film
124
which is formed on a side surface of the drop
172
is left on the conductive plug
107
as a residue
182
, and a contact resistance between the upper layer conductive plug
110
embedded in the upper layer contact hole
109
and the lower layer conductive plug
107
is increased as illustrated in FIG.
24
(
b
).
A reason why the drop
172
occurs in the conductive plug
107
is to over-etch or over-polish so that the conductive plug is securely embedded in an entire area of a wafer surface in consideration of uniformity of a film thickness on a surface of the wafer at time of forming the conductive plug or uniformity of an etching rate or, uniformity of polishing rate on the wafer surface.
SUMMARY OF THE INVENTION
It is an object of the present invention to solve the above-mentioned problems inherent in the conventional technique and to provide a semiconductor device having a contact structure comprising multi-layer conductive plugs, by which a short between the conductive plug and an electrode layer is prevented, and an electrical connection between upper and lower conductive plugs is stabilized to improve the reliability.
Another object of the present invention is to provide a semiconductor device including a contact structure of a capacitor comprising multi-layer conductive plugs, by which shorts between a capacitor electrode and an electrode layer and between the conductive plug and the electrode layer are prevented, and an electrical connection between upper and lower conductive plugs is stabilized to improve reliability.
Another object of the present invention is to provide a semiconductor device including a multi-layer wiring structure using a conductive plug, by which a short between the conductive plug and an electrode layer is prevented and an electrical connection between the conductive plug and a wiring layer is stabilized to improve reliability.
Another object of the present invention is to provide a method of producing a semiconductor device including a contact structure comprising multi-layer conductive plugs, by which a short between the conductive plug and an electrode layer is prevented, and a contact resistance between upper and lower conductive plugs is reduced.
According to a first aspect of the present invention, there is provided a semiconductor device comprising an electrode formed on a part of a semiconductor layer, a first insulating layer including a first insulating film and a first anti-reflection coating formed on the first insulating film, a first contact hole formed in the first insulating layer and reaching the semiconductor layer by penetrating a vicinity of side surface of the electrode layer from a surface of the first insulating layer, a first conductive plug embedded in the first contact hole and electrically connected to the semiconductor layer, a second insulating layer formed by covering the first insulating layer and the first conductive plug, a second contact hole formed in the second insulating layer and reaching the first conductive plug and the first insulating layer from a surface of the second insulating film, a second conductive plug embedded in the second contact hole and electrically connected to the first conductive plug, and a conductive layer formed in the second conductive plug and electrically connected to the semiconductor layer through the first conductive plug and the
Kang Donghee
McDermott & Will & Emery
Renesas Technology Corp.
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