JPH02267996A - Manufacture of thin film multilayer wiring board - Google Patents

Abstract

PURPOSE:To form accurately a fine thin film conductor pattern consisting of a plurality of layers by forming a flat organic insulating layer consisting of the 1st and 2nd coating films. CONSTITUTION:The formation of a coating film (polyimide film) is performed after dividing it two times so that a protruding part is buried on an irregular board 1. For the first time, polyimide liquid is applied in such an extent as to allow thickness obtained by heat-contraction to be almost equal to the difference in irregularities of the board 1 and after that, the coating film on the protruding part is removed. Then, subsequent contraction of the board under heat makes the upper surfaces of the polyimide film and the protruding part of the exposed board 1 uniform. Coating for the 2nd time is performed to make up a deficit of the thickness of the polyimide film. As originally coating film thickness is almost uniform, the whole surface contracts equally when heated and then the surface becomes flat. A fine thin film conductor pattern consisting of a plurality of layers is thus formed accurately.

Description

[Detailed Description of the Invention] [Summary] Regarding a method for manufacturing a thin film multilayer wiring board, the upper surface of each organic insulating layer is roughly formed so that multiple layers of fine thin film conductor patterns can be formed on the organic insulating layer with high precision. For the purpose of planarization, a conductor pattern formed on a substrate or an organic insulating layer is buried with a coating film of an organic insulating material (polyimide), and then a portion of the first coating film directly above the conductor pattern is removed. Next, heat is applied to shrink the first coating film to eliminate the level difference between the first coating film and the upper surface of the conductor pattern, and then an insulating material is coated on top of them to form a second coating film. After forming, the second coating film is contracted by heating to obtain an organic insulating layer composed of the first and second coating films.

[Industrial usage]

The present invention relates to a method for manufacturing a thin film multilayer wiring board.

Conventionally, glass epoxy multilayer boards have been mainly used as multilayer wiring boards for mounting LSIs used in computers, etc., but in order to promote higher performance and miniaturization such as increasing the calculation speed of computers, etc. In addition, requirements for wiring boards, such as packaging density, parasitic capacitance, heat resistance, thermal expansion, etc., are becoming more and more severe, and glass epoxy multilayer boards are no longer able to meet these requirements satisfactorily. Ceramic thick film multilayer substrates are also used, and although they are excellent in terms of heat resistance and thermal expansion, it is difficult to form fine patterns with high precision, so they are not suitable for LSI mounting. . Therefore, attempts have been made to accommodate wiring that does not include fine patterns, such as power supply circuits, in this ceramic thick film multilayer substrate, and to provide multiple layers of fine pattern wiring such as signal circuits with thin films on this substrate via polyimide. , has been put into practical use in some areas. This thin film multilayer part has excellent packaging density, parasitic capacitance, and heat resistance, and thermal expansion follows the ceramic substrate, so there is no problem. It is desired to put a thin film multilayer wiring board into practical use.

[Conventional technology]

FIGS. 2(a) to 2(e) show a method of manufacturing a thin 119 multilayer wiring board according to the prior art.

In FIG. 2(a), 1 is a ceramic substrate and 2 is a copper conductor pattern.

Apply polyimide liquid to the entire surface using the spin code method,
As shown in FIG. 2(b), an organic insulating layer 3 with a flat surface is formed.

Next, this was heated at about 100'C for about 1 hour to evaporate the solvent in the polyimide liquid, and then heated at about 400'C for about 30 minutes.
When heated for 1 minute, the resin becomes imide. This heating causes the organic insulating layer 3 to contract, producing irregularities on the surface as shown in FIG. 2(C).

Copper (not shown) is deposited on this organic insulating layer 3 by a spattering method or the like, and a second layer conductor pattern 2 is formed by a photoetching method as shown in FIG. 3(d). Thereafter, organic insulation M3 and conductor patterns 2 are alternately formed to manufacture a thin film multilayer wiring board.

Figure 2 (, e) shows an example of a thin film multilayer wiring board obtained in this way. A conductor pattern must be formed.

In the above description, the organic insulating layer 3 is obtained by applying the polyimide liquid once, but if the desired thickness is desired, the organic insulating layer 3 is applied in multiple times.

In addition, when forming the organic insulating layer 3 of a desired thickness by lowering the degree of stiffness of the polyimide liquid and applying it multiple times, there is an advantage that surface irregularities are reduced, but the processing time is significantly increased. Therefore, it is not practical.

(Problem to be Solved by the Invention) Since the top surface of each organic insulating layer is not flat in a thin film multilayer wiring board produced by such a conventional manufacturing method, the photo-etching process involves converting a flat photomask pattern onto an uneven surface. As the number of layers increases, the degree of unevenness on the top surface of the organic insulating layer tends to increase as the number of layers increases. The problem was that I couldn't do much.

An object of the present invention is to solve these problems and provide a method for manufacturing a thin film multilayer wiring board having multiple layers of fine thin film conductor patterns.

[Means for Solving the Problems] According to the present invention, after removing the portion of the first coating film coated with an organic insulating material directly above the conductor pattern, the first coating film is heated. Shrinking step, and after forming a second coating film by newly applying an organic insulating material on the first coating film and the conductor pattern after the heat shrinkage, heating and shrinking the second coating film. This is achieved by a manufacturing method of forming an organic insulating layer consisting of first and second coating films.

[Effect]

Polyimide resin is a stable resin that does not dissolve in most solvents, so in order to generate a polyimide film, it is dissolved in a solvent in the form of polyamic acid (this is called a polyimide liquid) and then applied, and then heated at a low temperature. Evaporate the solvent with
Next, a method is adopted in which a dehydration condensation reaction is caused by high temperature heating to form a polyimide resin. Therefore, volume reduction due to heating is unavoidable; in the case of a coated film, it can hardly shrink in the plane direction, so only the film thickness decreases.

If the polyimide liquid is applied to the uneven substrate so that the protrusions are buried, a substantially flat surface will be obtained initially, but
Since the polyimide film thickness is different between the convex and concave parts of the substrate, there is a difference in the amount of shrinkage during heating, and the polyimide solution is not flat. When the coating film thickness is
If D-t/N, the concave portion of the substrate will be L after heat shrinkage, but dXN will be added above t on the convex portion of the substrate, resulting in a step of dXN.

Therefore, the formation of the polyimide film is divided into two steps.In the first step, the polyimide liquid is applied to a thickness such that the thickness after heat shrinkage is equal to the difference in unevenness of the substrate, and then the coating film on the convex portions is removed. Heat shrink to align the top surface of polyimide B2 and the top surface of the protrusion of the substrate f6.

The second coating is to compensate for the lack of thickness of the polyimide film, and since the coated film thickness is originally approximately uniform, it shrinks uniformly by heating, and the surface becomes flat. In this way, a flat polyimide film can be obtained no matter how many layers are stacked on top of it.

〔Example〕

An embodiment of the method for manufacturing a thin one-dimensional multilayer substrate according to the present invention will be described with reference to FIGS. 1(a) to 1(h). Figure 1(a)
1, reference numeral 1 denotes a ceramic substrate, which itself has a multilayer structure, although not shown, and has a plurality of layers of thick film conductor patterns such as a power supply circuit formed thereon. 2 is a copper conductor pattern.

A photosensitive polyimide liquid is coated on the entire surface by a spin code method, and as shown in FIG. 1(b), the first coating F! !
Form 3a. The thickness of this first application r1.3a is:
When the thickness of the conductor pattern 2 is 5 μm and the resin concentration of the photosensitive polyimide liquid is 50%, the thickness is 10 μm.

Next, after pre-baking at about 50°C, apply W using a photomask having the same pattern as conductor pattern 2.
3. If the area other than the part directly above the conductor pattern 2 in 3a is exposed to ultraviolet rays and further developed, the photosensitive polyimide liquid has properties similar to those of a negative photoresist, and as shown in Fig. 1 (C).
As shown in FIG. 2, a portion of the coating film 3a directly above the conductor pattern 2 is removed.

Next, the solvent is evaporated by heating at about 100"C for about 1 hour, and then heated at about 400"C for about 30 minutes, the resin turns into polyimide and the coating film 3a shrinks to a thickness of about 5 μm. As shown in FIG. 1(d), the level difference with the conductor pattern 2 is eliminated.

When the polyimide liquid is applied again on this as shown in FIG. 1(e) and heated, a second coating film 3b is formed as shown in FIG. 1(f). The resin concentration of the polyimide liquid is 5
In the case of 0%, if the initial film thickness is 1071 m, it becomes 5 // m after heat shrinkage, and the total thickness is 10 m in total with the first coating film 3a.
An organic insulating layer 3 with a flat surface of .mu.m is completed.

A conductor layer is formed thereon by sputtering or the like, and this is etched by photoetching to form the second layer conductor pattern 2.

By repeating this method, a thin film multilayer wiring board as shown in FIG. 1 is manufactured.

In the following explanation, the first coating film 3a, the second coating film 3b
Although both are formed by applying the polyimide liquid once, they may be applied in multiple times.

Alternatively, a non-photosensitive polyimide liquid may be used; in this case, the first coating r! Additional steps such as photoresist application after pre-baking and removal of the photoresist after development are required in step 3a.

Note that the thicknesses of the first coated film 3a and the conductive pattern 2 after heat shrinkage do not necessarily have to be exactly the same, and some level difference is allowed.

〔Effect of the invention〕

As explained above, according to the method for manufacturing a thin film multilayer wiring board of the present invention, after removing the portion directly above the conductor pattern of the first coating film coated with an organic insulating material, the first coating film is coated with an organic insulating material. Heat-shrinking step, and after forming a second coated film by newly applying an organic insulating material on the first coated film and conductor pattern after the heat-shrinking, heat-shrinking the second coated film. By forming a flat organic insulating layer consisting of the first coating film and the second coating film through the steps, it becomes possible to form multiple layers of fine thin film conductor patterns with high precision, It greatly contributes to improving the performance and downsizing of computers, etc.

[Brief explanation of drawings]

FIGS. 1(a) to (h) are side sectional views for explaining the manufacturing process of an embodiment of the present invention, and FIGS. 2(a) to (e) are side sectional views showing the manufacturing process based on the conventional technology. It is. In the figure, 1 2 board, 2 ; conductor pattern, book-¥-Egt)XI;=f! Jt) r degree, aj i W
Figure 1 ([1) 3a: First coating film, 3b: Second coating film, 3: Organic insulating layer. Mokuzokubika no Mi Pseig・[01 Mutual Demonstration・12 Catty Face Ward'1st flash C in 02)

Claims (1)

[Claims] In the production of a thin film multilayer wiring board having a plurality of layers of conductor patterns (2) on a substrate (1) with an organic insulating layer (3) interposed therebetween, After removing the portion of the coating film (3a) directly above the conductive pattern (2), heating and shrinking the first coating film (3a); A second coating film (3b) is formed by newly applying an organic insulating material on the conductor pattern (2).
After forming the first and second coating films (3a, 3), the second coating film (3b) is heated and shrunk.
A method for manufacturing a thin film multilayer wiring board, which comprises forming an organic insulating layer (3) consisting of b).