JPS63255995A - Method of forming high density pattern - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high-density pattern forming method, and particularly to a pattern forming method for forming high-density wiring using photolithography technology for printed circuit boards and the like.

[Prior art]

Wet etching is used to form patterns on printed circuit boards and the like. As shown in FIG. 3, a temporary insulating base material 7
A layer 72 (copper plate, etc.) to be etched is adhered to the upper surface of the substrate 0. Further, an etching resist film is applied to the upper surface of the etching target layer 72, and a pattern of the etching resist layer 74 is formed by photolithography so that a predetermined pattern remains on the surface of the etching target layer 72. The layer to be etched 72 is immersed in an etching solution,
Alternatively, an etching solution is sprayed to dissolve and remove unnecessary portions of the layer 72 to be etched except for the area below the etching resist layer 74. As a result, a predetermined pattern of the layer 72 to be etched can be obtained on the base material 70 as shown in FIG.

However, in wet etching, dissolution of unnecessary portions proceeds isotropically, so at the end of etching, as shown in FIG. (referred to as side etching or over etching). Therefore, when the width A of the etching resist layer 74 is short, that is, when a high-density pattern is formed, there is a problem that the etched layer 72 is not sufficiently left as a pattern due to side etching.

Therefore, as a method to prevent side etching, the fifth method is
As shown in FIG. 5(A), the etching process is temporarily stopped, and as shown in FIG. 5(B), the layer 7 to be etched is removed.
A protective film 76 that is hardly soluble in an etching solution is formed on the surface of the etching solution 2. After forming the protective film 76, the etching solution is again sprayed as shown in FIG. 5(C) to retard the dissolution and erosion of the side surfaces of the layer 72 to be etched, which are left in the form of terraces.

[Problem that the invention seeks to solve]

However, in the conventional high-density pattern forming method described above, since the protective film 76 has uneven dissolution resistance strength to the etching solution, the etching of both sides of the layer 72 to be etched is difficult, as shown in FIG. 5(D). The amount is different, and there is a problem that the formed pattern is off center. Further, there is a problem that the cross-sectional area of the pattern formed in the layer to be etched is not constant.

The present invention has been made in view of the above circumstances, and an object of the present invention is to propose a high-density pattern forming method that can accurately form high-density patterns on printed circuit boards and the like.

[Means for solving problems]

In order to achieve the above object, the present invention forms a pattern of an etching resist layer on a layer to be etched, removes unnecessary portions of the layer to be etched that are not covered with the etching resist layer halfway, and then etches the etching resist layer. A protective film is formed on the surface of the layer to be etched which has been partially dissolved and removed, and a solution that dissolves the protective film but does not dissolve the layer to be etched is used to remove the layer to be etched remaining in a terrace shape below the etching resist layer. The method is characterized in that the protective film is dissolved except for the protective film portion covering the side surfaces, and unnecessary portions of the layer to be etched are removed again using an etching solution to form a predetermined pattern of the layer to be etched.

[Effect]

According to the high-density pattern forming method according to the present invention, the protective film other than the protective film covering the side surface of the layer to be etched that remains as the pattern to be etched is dissolved by the dissolving solution.
When the layer to be etched is dissolved and removed using an etching solution again, unnecessary portions are reliably dissolved and removed. On the other hand, since the side surfaces of the layer to be etched, which are the boundary lines of the pattern, are covered with a protective film, they are not eroded, and the side surfaces are reliably protected and a high-density pattern can be formed accurately.

〔Example〕

Preferred embodiments of the high-density pattern forming method according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a process diagram of a high-density pattern forming method according to the present invention. As shown in FIG. 1(A), a layer 12 to be etched is formed on the upper surface of an insulating base material 10.
2 is made of copper or the like.

An etching resist layer 14 having a predetermined pattern is formed on the upper surface of the layer 12 to be etched. The etching resist layer 14 is formed from a photosensitive resin having photocurability, such as DuPont's Riston 1220. When this etching resist layer 14 is cured by light, it becomes insoluble in organic solvents such as trichloroethane. Therefore, the predetermined pattern of the etching resist layer 14 can be formed using photolithography technology.

The formation pattern of the etching resist layer 14 shown in FIG. 1(A) is obtained using photolithography technology, and the width of the etching resist layer 14 is formed narrower than in the past, resulting in a high-density pattern.

Next, as shown in FIG. 1B, the layer 12 to be etched is removed using an etching solution. The treatment with the etching solution is carried out by directly immersing the layer 12 to be etched in the etching solution or by spraying it with etching solution. The etching of the layer 12 to be etched is stopped once the etching reaches about 2/3 of the thickness of the layer, and the etching process is continued until the etching reaches the state shown in FIG. 1(B).

A protective film 18 is formed on the surface of the etched layer 12 that has been partially etched by being immersed in a solution containing a protective agent or sprayed with a solution, as shown in FIG. 1(C). . As the protective agent forming the protective film 18, an alkylimidazole-copper chelating agent or the like is used. The alkylimidazole-copper chelating agent does not dissolve in alkaline conditions, but dissolves in acidic conditions. For this reason, the protective film 18 does not dissolve in alkaline etching solutions, but can be used in acidic etching solutions (for example, ferric chloride solution, cupric chloride solution, hydrogen peroxide solution, etc.).
Dissolves in sulfuric acid, ammonium persulfate solution). After the surface of the layer 12 to be etched is protected by the protective film 18, an acidic solution such as hydrochloric acid is sprayed onto the protective film 18. This spraying is carried out precisely from above and covers most of the protective film 18.
is dissolved except for the portion of the protective film 18 covering the side surface 12A of the layer to be etched 12, which remains in a terrace shape corresponding to the lower eaves of the etching resist layer 14.

Next, as shown in FIG. 1(E), the layer 12 to be etched is etched again.
is treated with an etching solution. At this time, an alkaline etching solution is used as the etching solution, and the protective film 18 is not dissolved in the etching solution because it is resistant to alkali. When etching is performed in this state, the etching process shown in Fig. 1 (F
), side surfaces 12A, 12A of the terrace-shaped layer 12 to be etched covered with the protective film 18 remain uninfiltrated;
The layer to be etched 12 is left below the etching resist layer 14.

According to the high-density pattern forming method of the present invention configured as described above, the layer to be etched 12 that has been etched halfway has side surfaces 12A formed in a terrace shape as shown in FIG. 1(D). . only are covered with the protective film 18, so when the layer 12 to be etched is etched again, the side surfaces 12A of the formed pattern are not attacked. Therefore, a high-density pattern of the layer 12 to be etched is accurately left on the substrate 70. For example, according to the high-density pattern forming method according to the present invention, the resist width of the layer to be etched 12 is set to 70 mm on the insulating base material 10. clm, and can be formed with an etching interval of 70 to 100 μm. Furthermore, since both side surfaces 12A, 12A of the formation pattern of the layer to be etched 12 are not unevenly infiltrated from both sides as in the conventional case, the pattern of the layer to be etched 12 is formed at an accurate position on the base material 10. Ru.

FIG. 2 is a process diagram showing a second embodiment of the present invention. The layer 12 to be etched in FIG. 2(A) has been subjected to the same treatment as the layer to be etched 12 in FIG. 1(D). Side surfaces 12A of the layer to be etched 12 formed in a terrace shape are covered with a protective film 18. In this state, the layer 12 to be etched is first washed with water and then dried. By drying, the strength of the protective film 18 increases as shown in FIG. 2(B), and the layer to be etched 12 can be reliably protected from the etching solution. In this protected state, the layer 12 is treated with an etching solution again, and a precise pattern of the layer 12 to be etched is formed as shown in FIG. 2(D).

〔Effect of the invention〕

According to the high-density pattern forming method of the present invention, a protective film is formed on the surface of the layer to be etched which has been partially dissolved and removed, and a terrace-like pattern is left below the etching resist layer using a solution for the protective film. The protective film other than the protective film covering the side surface of the layer to be etched is dissolved and the layer to be etched is treated again with an etching solution to form a predetermined pattern, so the pattern formed on the substrate etc. can be made more densely and accurately. be able to.

[Brief explanation of drawings]

FIGS. 1(A) to (F) are process diagrams of the high-density pattern forming method according to the present invention, and FIGS. 2(A) to (D) are process diagrams of the high-density pattern forming method according to the present invention. The process diagram shown in FIG. 3 is a cross-sectional view of the layer to be etched formed on the base material,
Figure 4 is a cross-sectional view of the layer to be etched after etching treatment;
FIGS. 5A to 5D are process diagrams of a conventional high-density pattern forming method. 10... Insulating base material, 12... Layer to be etched,
14... Process/notching resist layer, 18... Protective film. Applicant Hitachi Plant Construction Co., Ltd. Prisoner 1 (A) CB) (C) 10. Insulating base material, 12. Etched layer, 14
...Etch resist layer, 18...Protective film 6 Fig. 2 (A) (C) Fig. 3 Fig. 4

Claims (4)

[Claims] (1) A pattern of an etching resist layer is formed on the layer to be etched, and unnecessary parts of the layer to be etched that are not covered by the etching resist layer are partially removed using an etching solution, and the part of the layer to be etched that has been partially dissolved and removed is removed. A protective film is formed on the surface, and a solution that dissolves the protective film but does not dissolve the layer to be etched is used to remove the part of the protective film covering the sides of the layer to be etched, which is left in a terrace shape below the etching resist layer. A method for forming a high-density pattern, characterized in that the protective film is dissolved by the etching process, and unnecessary portions of the layer to be etched are removed again using an etching solution to form a predetermined pattern of the layer to be etched. (2) The method for forming a high-density pattern according to claim 1, further comprising the step of drying and strengthening a protective film covering the terraced side surfaces of the layer to be etched. (3) The high-density pattern forming method as set forth in claim 1 or 2, wherein the protective film is an alkylimidazole-copper chelate coating. (4) High-density pattern formation according to claim 1, 2, or 3, characterized in that after dissolving the protective film, the etching solution used to etch unnecessary parts again is alkaline. Method.