JPS63216361A - Multilayer interconnection structure - Google Patents

Abstract

PURPOSE:To shorten a production process by a method wherein the connection between wiring layers is executed by using a wiring connection body coated on a through hole which has been made by exposing the side of the wring layers so that the through hole at a multilayer interconnection can be made by only one process. CONSTITUTION:The connection between wiring layers 3a-3c at a laminated structure formed by piling up insulating films 4a-4c where the wiring layers 3a-3c are buried, on a semiconductor substrate 1 is executed by using a wiring connection body 7 coated on a through hole 6 which has been made by exposing the side of the wiring layers 3a-3c to be connected. For example, the through hole 6 is made at the insulating films 4a-4c by an anisotropic dry etching method or the like so that the side of the wiring parts 3a-3c at the first to the third layers can be exposed. A Ti layer 7a and a Pt layer 7b are formed one after another as the wiring connection body 7 on the inside wall of the through hole 6 by a sputtering method; furthermore, an Au layer 7c is formed on the Pt layer 7b by a plating method; the wiring parts 3a-3c at the first to the third layers are connected electrically to one anther by using the wiring connection body 7.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a multilayer wiring structure of a semiconductor device.

[Conventional technology]

Conventionally, in a semiconductor device having multilayer wiring, when forming, for example, n-layer metal wiring, it has been necessary to form an electrical connection window between each metal wiring (n-1 times), that is, to open a through hole. For example, as shown in FIG. 3, three-layer wiring 3a, 3b,
3c, the through hole 5 (1) between the wirings 3a and 3b and the through hole 5 (2) between the wirings 3b and 3c.
It was necessary to open holes in the insulating films 4a and 4b.

In the above-mentioned conventional multilayer wiring structure, the upper layer wiring is prone to disconnection at the edge of the through hole, so it is necessary to etch the through hole + r - par shape, and the lower part of the through hole does not protrude from the lower layer wiring. The upper part of the through hole must be completely covered by the upper layer wiring. This imposes many restrictions on design and manufacturing.

Furthermore, since the connection from the first layer wiring to the nth layer wiring is made through the (n-1) through holes as described above, there is a drawback that the more layers there are, the more likely connection failures will occur at the through hole portions.

SUMMARY OF THE INVENTION An object of the present invention is to provide a multilayer wiring structure with novel wiring connections that eliminates the above-mentioned drawbacks.

[Means for solving problems]

The multilayer wiring structure of the present invention is a structure in which insulating films in which wiring layers are embedded are stacked on top of a semiconductor substrate, and connections between wiring layers are made through through holes that expose the sides of the wiring layers to be connected. This is done by a wiring connection body attached to the.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a case where three layers of aluminum wiring are formed as an example. On the silicon oxide film 2 on the silicon substrate 1, there are formed a first layer wiring 3a and an insulating film 4a covering it, a second layer wiring 36 and an insulating film 4b covering it, and a third layer wiring 3C and an insulating film 4b covering it. cover insulation j14c
are formed by sequentially stacking them.

Next, first layer arrangement 3al second layer scale +1!3b.

The insulating film 4a is formed so that the side surface of the third layer wiring 3C is exposed.
, the insulating film 4b, and the insulating film 4C by anisotropic dry etching or the like, and then Ti is deposited on the inner wall of the through hole 6 as a wiring connection body 7 by sputtering.
A layer 7a of Pt layer 7b is formed, and further P is coated by a plating method.
An Au layer 7c is formed on the t-layer 7b. The first layer wiring 3a, the second layer wiring 3b, and the third layer wiring 3C are electrically connected to each other by the wiring connection body 7.

Connections between wirings do not need to be made through all wiring layers as in the conventional example, and wiring layers to be directly connected can be connected through all through holes. FIG. 2 shows an example in which the first layer wiring 3a is directly connected to the third layer wiring 3C via a wiring connection body 9f. The wiring connected by the through hole 8 whose position is changed in this way can be changed.

〔Effect of the invention〕

As explained above, in the present invention, the through holes are formed after all the wiring layers are formed, so the through hole forming process can be performed only once no matter how many wiring layers there are, and the manufacturing process can be shortened. Since it is only necessary to form the wiring so that a part of the side surface of each wiring is exposed, there is no need to consider the design margin of the wiring and through-holes as in the conventional case, which has the effect of simplifying the design. In addition, as an effect of the present invention, an improvement in reliability can be expected as shown below.

(a) Since the connections between the wirings in each layer are made through one through hole, the probability that a connection failure will occur at the through hole portion is extremely reduced.

(b) Since wiring is not formed on the through-hole, there is no risk of disconnection at the through-hole portion of the upper layer wiring.

Furthermore, for semiconductor devices such as gate arrays that require a variety of wiring connections, the present invention allows for the creation of through-holes to connect any wiring at any location after forming all the wiring. construction period can be shortened.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of an embodiment of the present invention, and FIG. 3 is a cross-sectional view of a conventional example. 1... Silicon substrate, 2... Silicon oxide film, 3a
, 3b, 3c... (aluminum) wiring, 4a
, 4 b, 4 c ---insulating film, 6.8...
Through hole, 7.9... Wiring connection body.

Claims (1)

[Claims] It has a laminated structure in which an insulating film with embedded wiring layers is layered on a semiconductor substrate, and connections between wiring layers are made through through holes that expose the sides of the wiring layers to be connected. A multilayer wiring structure for a semiconductor device, characterized in that it is formed by a wiring connection body.