JPS60111243A - Method for etching organic polymer film - Google Patents

Abstract

PURPOSE:To form a through hole small in opening diameter through a comparatively thick org. polymer film by using a chemical etching mask having a 2-layer structure of an inorg. film and a photoresist. CONSTITUTION:An org. polymer film 2, an inorg. film 5, and a photoresist 3 are succussively laminated on a substrate 1, a desired pattern is formed, the inorg. film 5 is etched off, further, and the polymer film 2 is also etched off to form a through hole 4. As the inorg. film 5, a single layer film made of one of Ti, Cr, Al, Mo, etc., a multilayer film formed by combining some of them, further, a single layer film made of one of SiO2, Si3N4, Al2O3, etc., and a multilayer made of combination of some of them. A small through hole 4 can be formed by etching the org. polymer film.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for etching an organic polymer film, that is, a method for forming high-density multilayer wiring using an organic polymer film as an insulating layer in integrated circuits and integrated circuit pancakes, and more specifically, This invention relates to a method of forming fine holes with a small opening diameter in an organic polymer film using a chemical etching method using a double layer film of an inorganic film and a photoresist as a mask.

A multilayer wiring formation method using an organic polymer film as an insulating layer between the eyebrows has been conventionally used in integrated circuits and the like. As shown in FIG. 1, this method involves laminating an organic polymer film (for example, polyimide resin) 2 on a substrate 1, and then layering a cyclized rubber-based negative photoresist 3 (for example, 0MR83i Tokyo Ohka). , on,) and perform the desired patterning, using an etchant containing hydrazine as a main component (for example, PiQ etchant; available from Hitachi Chemical),
A through hole was formed.

The thickness of the insulating film between the eyebrows, that is, the organic polymer film 2 formed on such an integrated circuit is as thin as about 3 μm at most.

On the other hand, with recent advances in semiconductor technology, wiring with small signal propagation delay time has become necessary, especially in integrated circuit patterning, and for this reason, the insulating film between wiring layers is formed relatively thick, approximately 10 μm or more. , efforts are being made to reduce wiring capacitance.

However, when applying the conventional etchant method to through-hole processing of the above-mentioned relatively tough polyimide film, hydrazine, the main component of the etchant, may permeate the photoresist film or penetrate into the interface between the polyimide resin 2 and the photoresist 3. As shown in Figure 1, the opening size of the through hole increases due to penetration, and the taper angle generally increases to 4.
Since a large through ball of 5° is formed, there is a drawback that it is difficult to miniaturize the opening diameter.

The present invention has been made in view of the above points, and provides a method for forming through balls with a small opening diameter in a relatively thick organic polymer film using a chemical etching mask consisting of a two-layer film structure of an inorganic film and a photoresist. The purpose is to provide.

Therefore, in the method of etching an organic polymer film according to the present invention, the organic polymer film is selectively chemically etched using an etching mask to open holes. It is characterized in that an inorganic film and a photoresist are sequentially laminated on the film.

Hereinafter, the method according to the present invention will be explained in detail using the drawings.

FIG. 2 is a cross-sectional view of a through hole formed by the etching method according to the present invention. In the figure, 1 is a substrate, 2 is an organic polymer film, 3 is a photoresist, and 5 is an inorganic film. .

FIG. 2 shows that an organic polymer film 2, an inorganic film 5, and a photoresist 3 are sequentially formed on a substrate 1, and after desired patterning is performed, the inorganic film 5 is removed by etching, and then an organic polymer film 2 is etched. 4 is a cross-sectional view of the through hole 4 formed by etching away the through hole 4.

As the above-mentioned organic polymer film 2, for example, an organic polymer film such as polyimide resin or silicone resin can be used. The selection of the above-mentioned organic polymer film and the etchant used to etch it takes into consideration the type of inorganic film used by i-friends. It is best to select a combination of polymer film and etchant. Examples of such etchants include hydrazine etchants and alkaline etchants.

In addition, the inorganic film 5 may be a single layer film selected from Ti5CrsAl, MO, etc. or a multilayer film thereof;
Furthermore, a single layer film selected from Si09, Sia Na, AIQOs, etc. or a multilayer film thereof can be used. In addition, the aforementioned Ti, Gr, AI
, Mo, etc., and SiO+1.5iaN
It can also be a multilayer film combining films selected from &, Al2O3, etc.

Furthermore, as the photoresist layer 3, those conventionally used as this type of photoresist can be effectively used. For example, the aforementioned cyclized rubber photoresist,
A carbonized polybutadiene photoresist or the like can be used.

In such a configuration, by etching the organic polymer film 2, smaller through holes can be formed compared to the conventional method. In other words, compared to the case of using a single layer of either photoresist or metal film, by using both photoresist and inorganic film, the permeation of hydrazine-based etchant can be prevented, and the difference between inorganic film and polyimide-based resin can be prevented. This is because the adhesive property is good, so there is no etchant penetration.

The present invention will be explained in detail below.

Examples Polyimide resin (PIQ: manufactured by Hitachi Chemical Co., Ltd.) was used as the organic polymer film, Ti metal film formed by electron beam evaporation etc. was used as the inorganic film, and CBRM901 (produced by Nippon Synthetic Rubber Co., Ltd.), which is a carbide polybutadiene-based photoresist, was used as the photoresist. ,)
, anisotropic etching is possible for Ti etching,
PQI etchant, which is mainly composed of hydrazine, is suitable for forming fine patterns and is suitable for active ion etching and etching polyimide resins.
) was used.

The film thickness of the polyimide resin was approximately 10 μm due to multilayer film formation, and the film thickness of the Ti film was approximately 1 μm. Also,
The temperature of the PQI etchant was kept constant at about 30°C.

Etching was performed under these conditions to form through holes.

Assuming that the pattern deviation between the edge of the mask and the area around the top of the through-hole is 6, and the pattern deviation between the area around the top and bottom of the through-hole is 7, the relationship between these experimental values after through-hole formation and 8 in the mask is as follows: The result is shown in Figure 3.

As is clear from FIG. 3, the undercut 6 is about 4 μm, which is as small as 1/3 of the polyimide resin film thickness.
The side cut 7 was about 7 μm, and the through-hole angle was about 60°. That is, compared to the conventional method using only a photoresist as a mask, etching processing with strong anisotropy can be performed.

In this way, by performing chemical etching using a two-layer film of an inorganic film and a photoresist, it has become possible to form fine through holes.

In the above embodiments, a Ti metal film is used as the inorganic film, but any single layer film of Cr, AI, or MO or any multilayer film of Ti, Cr, AI, or Mo may be used. The same results as with Ti were obtained.

Furthermore, as inorganic films, SiO2, Si3N4, Al2
Any single film of O3 or SiOl! , 5f3
Even if any multilayer film of N 4 and AI203 is used, the Tr
Similar results were obtained.

In addition, as inorganic films, Ti, Cr, AI, MO1S
iO1! , Si3 Na , and A1203, the same results as in the case of Ti were obtained.

Further, as the organic polymer film of this embodiment, an organic polymer film such as silicone resin can also be used. Specifically, inorganic films include Ti, Cr, AI, MOlSiO$
A single layer film or any multilayer film such as 1% Si3N A or Alp Oa is used, and the type of this inorganic film is considered to have low etchant permeation and to be compatible with organic polymer films and V&V.
It is better to select a combination of an organic polymer film and an etchant that will less permeate into the film.

As explained above, according to the etching method of the present invention, a two-layer film of an inorganic film and a photoresist can be used as an etching mask for relatively thick polyimide resin or silicone resin using a hydrazine etchant. This enables highly anisotropic etching, which has the advantage of forming through holes with small opening diameters.

Since deep through balls can be formed finely and with high density in this manner, there is an advantage that it is easy to form high-density multilayer wiring with a small signal propagation delay time.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a through hole formed by a conventional chemical etching method, FIG. 2 is a sectional view of a through hole formed by an embodiment of the present invention, and FIG. 3 is a sectional view of a through hole formed by an embodiment of the etching method of the present invention. FIG. 3 is a diagram showing the relationship between the sidecuts and undercuts of through-holes and the mask. 1...Substrate, 2...Organic polymer film, 3...
Photoresist, 4...Through hole, 5...Inorganic film, 6...Undercut 7...Side cut, 8...In mask. Applicant's agent Tadashi Amemiya 43 Figure 2 Figure 3 Mask width CP m)

Claims (1)

[Claims] (11) A method for etching an organic polymer film in which organic polymer II is selectively chemically etched using an etching mask to open holes. , a method for etching an organic polymer film, characterized in that an inorganic film and a photoresist are sequentially laminated and etched. (2) the organic polymer film is a polyimide-based tree n-,
The inorganic film is TtSCr, AI, Mo, SiOt
3. The method of etching an organic polymer film according to claim 1, wherein the etching method is a single layer film or a multilayer film of 11 or more layers selected from the group consisting of , 5iaN4, and AllOa.