JPH0528500B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method for forming multilayer wiring using an interlayer insulating film having a two-layer laminated structure of photosensitive heat-resistant resin.

[Background of the invention]

The conventional multilayer wiring structure and its manufacturing method are
As shown in Figure 2. That is, after forming the first layer wiring conductor 2 on the substrate 1, a prepolymer of PIQ (trademark of Hitachi Chemical) is applied, and finally it is heated and cured at a temperature of 300°C or higher to form the first polymer. PIQ layer 3, which is a wood insulating film, is formed. Next, after providing a connection window 4 at a predetermined position, a second layer of wiring conductor 5 is formed, a PIQ layer 6 is provided on the wiring conductor 5, and a connection window 7 is formed. A third layer of wiring conductor 8 is formed. In this way, PIQ layers 3, 6, connection windows 4, 7 and wiring conductors 2, 5, 8
By repeating the formation of the above steps, it is possible to form a multilayer interconnection in which many layers are stacked.

However, the connection windows 4 and 7 were formed by covering the PIQ layer with a negative type photoresist, and selectively etching it with a mixed solution of hydrazine hydrate and ethylenediamine after exposure and development. In this case, the etching solution etches the fully cured PIQ layer. For this reason, if the mask alignment of the connection windows 4 and 7 is misaligned and the connection window 7 deviates from the width of the lower wiring conductor 5, the lower PIQ layer 3 will also be etched, which is unfavorable in terms of the reliability of the multilayer wiring.

Therefore, the width of the second layer wiring conductor 5 needed to be formed sufficiently wide, taking into consideration alignment accuracy and dimensional variations. For this reason, the width and spacing of the second layer wiring conductors 5 cannot be made sufficiently small, which may impede the formation of high-density multilayer wiring due to miniaturization of the wiring.

As a countermeasure to this problem, there is a multilayer wiring structure and a manufacturing method described in Japanese Patent Application Laid-Open No. 59-106136. The manufacturing method will be explained with reference to FIG.

First layer wiring 2, first PIQ layer 3, connection window 4 and second layer wiring 5A are formed on substrate 1 in the same manner as the conventional method shown in FIG. Next, the PIQ prepolymer solution was spin-coated on the PIQ layer 3 again and semi-cured, and then a negative type photoresist was applied.
After exposure and development to form a connection window pattern on the second PIQ layer 6A, the hardened PIQ is not etched, but the semi-hardened PIQ is etched to form the connection window 7A.
form. In this case, use 25% tetramethylammonium hydroxide as the etching solution.
Use an alcoholic solution containing

After forming the connection window 7A, final baking is performed.
After completing the PIQ layer 6A, the third layer wiring 8A is further formed. According to such a method, the lower resin (PIQ) layer 3 is not etched when the upper layer connection window 7A is etched, so that the second layer wiring 5
It is possible to reduce the width of A.

However, with this method, it is necessary to process the upper layer connection window 7A in a semi-hard state, so the PIQ layer thickness during processing is larger than in the conventional method (Fig. 1), making microfabrication easier. There is a drawback.

[Purpose of the invention]

It is an object of the present invention to solve the problems of the prior art as described above, and to provide a method for forming multilayer wiring that allows high integration, has good processing accuracy of connection windows, and requires a small number of steps. That is.

[Summary of the invention]

In order to achieve the above object, the present invention includes a first step of forming a first layer of wiring and a first photosensitive heat-resistant resin layer forming a first connection window on a substrate, and a second step of forming a first layer of wiring and a first photosensitive heat-resistant resin layer on the resin layer. A method for forming a multilayer wiring comprising a second step of forming a layer wiring, a second photosensitive heat resistant resin layer forming a second connection window, a third layer wiring, etc., wherein the second photosensitive heat resistant resin in the second step The layer is formed by coating a photosensitive heat resistant resin on the first photosensitive heat resistant resin layer in the first step, and then forming a photosensitive heat resistant resin layer forming the second connection window by exposure and development. By repeating the layer forming process again, a double layer structure having double connection windows is formed.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a multilayer wiring structure to which the formation method of the present invention is applied. In the same figure, on a substrate 1, first layer wiring 2,
A PIQ layer 3, a connection window 4 and a second layer wiring 5B are formed.

A photosensitive heat-resistant resin varnish, such as Photo-PAL (Hitachi Chemical trademark), is applied on the PIQ layer 3 and the connection window 4.
After spin coating, pre-bake at 85°C for 15 minutes. Then, 100mJ/
cm ² (at 365 nm), developed with a developer mixture of NMP (N-methyl-upyrrolidone) and water at a ratio of 4:1, and exposed to 400 nm in N ₂ at 180°C for 30 minutes.
A step cure is performed for 60 minutes in _N2 at a temperature of 0.degree. C. to form a photosensitive heat-resistant resin layer _6B1 that forms a connection window _7B1 . By repeating such a resin layer forming process again, a photosensitive heat-resistant resin layer 6B ₂ forming the connection window 7B ₂ is formed, and a second photosensitive heat-resistant resin layer having a double structure having a double connection window 7B is formed. Form 6B. Next, in the same way as the conventional method, the third layer wiring 8B
form.

Although this embodiment describes a method for forming a multilayer wiring having a second photosensitive heat-resistant resin layer 6B consisting of two layers, the present invention is not limited thereto, and can also be applied to the formation of a multilayer wiring having three or more layers. be.

According to this embodiment, when forming the connection window 8B in the second photosensitive thermoresin layer 6B, there is no need to etch the PIQ layer 3, so the width of the second layer wiring 5B can be reduced. It is possible to increase the density of the second layer wiring 5B. Further, since the connection window 7B is formed by two-step processing, the thickness of the photosensitive heat-resistant resin layer during each processing becomes smaller, so that fine processing is possible.

On the other hand, in order to cope with the increase in the number of steps due to two-step processing, by using a photosensitive polyimide that has both the functions of a photoresist and a photosensitive heat-resistant resin layer,
The number of steps can be less than the number of steps in the conventional method.

〔Effect of the invention〕

As explained above, according to the present invention, there is no need to provide a wiring connection pattern larger than the connection window in the lower photosensitive heat-resistant resin layer, so it is possible to increase the integration of multilayer wiring, and to process the connection window. It is possible to improve accuracy and reduce processing man-hours.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a multilayer wiring structure to which the method of forming a multilayer wiring according to the present invention is applied, and FIGS. 2 and 3 are sectional views of each multilayer wiring structure formed by a conventional method. 1... Board, 2, 5B, 6B... First, second,
Third layer wiring, 3, 6B...first and second photosensitive heat-resistant resin layers, 7B...second connection window.

Claims (1)

[Claims] 1. A first step of forming a first layer wiring and a first photosensitive heat-resistant resin layer forming a first connection window on a substrate, and forming a second layer wiring and a first layer wiring on the resin layer. 2. In a method for forming a multilayer wiring comprising a second photosensitive heat-resistant resin layer forming a connection window and a second step of forming a third layer wiring, etc., the second photosensitive heat-resistant resin layer in the second step is After applying a photosensitive heat resistant resin on the first photosensitive heat resistant resin layer in the first step, a photosensitive heat resistant resin layer forming a second connection window is formed by exposure and development,
A method for forming a multilayer wiring, characterized in that a double layer structure having double connection windows is formed by repeating such a resin layer forming step again. 2. The method of forming a multilayer wiring according to claim 1, wherein the width of the second layer wiring is set to be approximately equal to or less than the dimension of the second connection window.