Connection structure

Details Connection structure Connection structure

2000-07-07

2002-08-13

Paladini, Albert W. (Department: 2827)

Electricity: conductors and insulators

Conduits, cables or conductors

Preformed panel circuit arrangement

C174S261000, C029S852000, C257S698000, C438S637000

Reexamination Certificate

active

06433287

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a connection structure, and particularly to a connection structure of a contact portion in a conductive-member construction in which heavy current flows.
2. Description of the Related Art
In order to realize high integration of a semiconductor device such as IC or LSI, a technique in which wiring is mutually conducted between elements formed in a multi-layered structure with high density is very important. Conventionally, in order that electric connection be made between elements formed in a multi-layered structure and electrically isolated by an interlayer insulating film, and between wirings, and also between an element and a wiring, for example, a via hole structure in which electric connection is made for elements or wirings, which are formed in layers at upper and lower sides of an interlayer insulating film, with conductive materials being embedded in through holes formed in the interlayer insulating film, or connection structures as shown in
FIGS. 8A
to
8
C,
9
A and
9
B are employed.
FIGS. 8A
,
8
B, and
8
C show an example of a connection structure of two wirings, which extend in directions perpendicular to each other and are formed in a layered form via an interlayer insulating film
34
. An end of a first wiring
30
provided as a lower layer and an end of a second wiring
32
provided as an upper layer are connected via a through hole.
This connection structure is obtained in such a manner as will be described below. First, as shown in
FIG. 8B
, the interlayer insulating film
34
is formed by a CVD method on the first wiring
30
, and thereafter, a rectangular hole is formed in the interlayer insulating film
34
at the end of the first wiring
30
so as to become a through hole
16
. As shown in
FIG. 8C
, an extension wiring
32
is formed on the interlayer insulating film
34
so as to cover the through hole
16
.
FIGS. 9A and 9B
show an example of a connection structure of a diffusion layer
35
provided in a substrate
20
and an extension wiring
11
d.
As illustrated in the plan view of FIG.
9
A and in the cross-sectional view of
FIG. 9B
, a through hole
16
is provided in an interlayer insulating film
34
b
formed by a CVD method or the like on an entire surface of the substrate
20
in which the diffusion layer
35
forming semiconductor elements is formed, so as to expose the diffusion layer
35
. An extension wiring
32
b
having a connection region
31
which covers the through hole
16
, is provided on the interlayer insulating film
34
b.
A through hole contact
18
(for example, see
FIGS. 8A
,
8
B,
8
C,
9
A, and
9
B), that is a portion in which electric connection is made between such elements, and between wirings, and also between an element and a wiring and is a bottom surface portion of the through hole, is formed in such a manner that electric current is apt to concentrate therein. In order to obtain a semiconductor device having higher reliability than a conventional one, it is important to prevent increase of current density due to concentration of electric current in the through hole contact. For this reason, it becomes important to use materials having a low resistance and good ohmic properties in a region of the through hole contact or to provide a structure in which no local concentration of electric current occur.
Accordingly, there has conventionally been proposed a method in which an area of the through hole contact is increased by increasing a transverse dimension of a wiring disposed as a lower layer or by increasing the size of a through hole, so as to reduce current density. For example, in a case of Emitter-Coupled Logic (ECL) circuit, electric current flows between the lower-side wiring and the upper-side wiring via the through hole contact in a unit from several tens of mA to several hundreds of mA. Therefore, the transverse dimension of the wiring and the size of the through hole are each made relatively larger to become several tens of &mgr;m to several hundreds of &mgr;m so that an allowable current density becomes about 1×30
5
(A/cm
2
) or less.
However, in a conventional multi-layered wiring structure having a through hole contact, there exists a problem in which local concentration of electric current is caused and so-called electromigration such as void or hillock thereby occurs.
For example, in the structure in which the first wiring
30
at the lower side and the second wiring
32
at the upper-side are connected together so as to be made perpendicular to each other as shown in the plan view of
FIG. 8A
, in a case in which electric current flows from the first wiring
30
to the second wiring
32
, assuming that the length of each side of the through hole contact
18
is indicated by “l”, a distance between an end of the second wiring
32
to one side of the through hole contact
18
is indicated by “m”, a distance between an end of the first wiring
30
to one side of the through hole contact
18
is indicated by “n”, positions on the first wiring
30
at which straight lines drawn from corners of the through hole contact
18
perpendicular to a side of the second wiring
32
cross the side of the second wiring
32
are indicated by “A
1
” and “A
3
”, a position at a midpoint of positions A
1
and A
3
on the first wiring
30
is indicated by “A
2
”, and a position on the second wiring
32
where a straight line drawn from a corner of the through hole contact
18
nearest the above-described positions A
1
, A
2
, and A
3
perpendicular to a side of the first wiring
30
crosses the side of the first wiring
30
is indicated by “B”, a length of a shortest path of current flowing from each position A
1
, A
2
, and A
3
to the second wiring
32
can be expressed artificially as described below.
|
A
1
B|=m+n+
1  (1)
|
A
2
B|=m+n+
(1/2)1  (2)
|
A
3
B|=m+n
  (3)
wherein, |A
1
B| indicates a length of a shortest path between point A
1
, and point B, |A
2
B| indicates a length of a shortest path between point A
2
and point B, and |A
3
B| indicates a length of a shortest path between point A
3
and point B.
The relation |A
1
B|>|A
1
B|>|A
1
B| is given by the abovedescribed expressions (1), (2), and (3), and therefore, the path indicated by A
3
B is the shortest. Accordingly, it is considered that electric current concentrates in one corner of the through hole contact
18
on the path of A
3
B.
If current concentrates, void or hillock may be generated at a high frequency, and there is a high possibility that after a fixed period of time has elapsed, electromigration may occur to cause improper wiring. Particularly, as shown in
FIG. 8C
, in a case of a wiring structure including a through hole, a layer thickness of a wiring in a region which covers a side surface portion of the through hole is small, and therefore, there is also a possibility that a thin layer portion of the wiring is molten and broken by occurrence of electromigration or generation of heat due to concentration of current.
Further, in a case of the structure shown in
FIGS. 9A and 9B
, current is apt to concentrate in a side surface portion of the through hole disposed perpendicular to a direction in which current flows. In this case as well, the layer thickness of a wiring in a region which covers the side surface portion of the through hole is small, and therefore, there is a possibility that a thin layer portion may be molten and broken due to occurrence of electromigration or generation of heat.
SUMMARY OF THE INVENTION
In view of the above-described circumstances, it is an object of the present invention to provide a connection structure in which concentration of current is prevented in a portion in which wirings, or an element and a wiring are connected.
In order to achieve the above-described object, in accordance with a first aspect of t

Affiliated with

Also associated with

Rating

Connection structure does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Connection structure, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Connection structure will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2884654