JPS60173713A - Surface leveling method of substrate with thin film pattern - Google Patents

Abstract

PURPOSE:To make the surface flat easily with a high precision by using already formed thin film patterns as photomasks to form resist patterns in the lift-off method where resist patterns are peeled and removed together with insulating films. CONSTITUTION:A positive photoresist is applied to the surface of a transparent substrate 1, on which thin film patterns 2 are formed, by a spin coating method or the like to provide a photoresist layer 3, and rays such as ultraviolet rays or the like are irradiated from the rear face of the substrate to expose it, and development processing is performed to remove the photoresist only in exposed parts, and thus, the same resist patterns 3' as thin film patterns are obtained. Next, an insulating layer 4 is formed on the transparent substrate 1 with the same thickness as thin film patterns 2 by sputtering or the like. The obtained substrate is processed with a resist removing liquid to peel the photoresist, and thus, the flat surface of the substrate where recessed parts of thin film patterns 2 are filled with insulating layer patterns 4' is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for planarizing the surface of a transparent substrate having a thin film pattern.

[Description of Technical Field] In recent years, with the development of thin film formation technology, photophosphorography, and etching technology, it has become possible to fabricate and apply various devices using fine patterns of P1ζ films. Examples of such devices include semiconductor devices such as ICs and LSIs, liquid crystal display devices, thin lI* magnetic heads,
Examples include thermal heads. In manufacturing these devices, a large number of thin film patterns are stacked on a substrate by sequentially performing thin film formation and fine processing such as etching on the surface of the substrate.

For example, in an inductive RTUII magnetic head, a magnetic film such as permalloy or sendust, an insulating film such as 5i02 or A203, and a conductive metal film such as A2, Cu, or Au are formed on a substrate made of glass, quartz, sapphire, etc. After each film is formed using various film forming methods (sputtering method, vapor deposition method, plating method, etc.), it is patterned using a resist, and the thin film patterns are sequentially created using chemical etching, dry etching, etc. A lower magnetic pole, an upper magnetic pole, an electrical insulating film, a coil, a front gap film, etc. are provided.

[Description of the prior art tJ1] In the method of manufacturing an element such as a magnetic head having a multilayer thin film pattern as described above, various problems are likely to occur due to the unevenness of the thin film pattern.
Problems include disconnections between conductors caused by so-called "one-step breaks," poor insulation between each conductor or between magnetic poles, and leakage of magnetic flux caused by insufficient spacing between the upper and lower magnetic poles. There is. In order to solve the problems caused by the unevenness of the thin film pattern.

Various methods have been developed for flattening the surface of a film provided on a substrate.

As a method for flattening the surface of such a substrate with a thin film pattern, for example, (1) After providing an insulating film with the same thickness as the thin film pattern on a substrate having a thin film pattern, A method in which complementary resist patterns are formed on the insulating film using a photomask, then the insulating film on the thin film pattern is etched away, and finally the resist is removed; (2) First, the thin film is formed on the substrate. Pattern formation, PJ
This is done by forming a resist layer with the same pattern as the desired pattern, etching the thin film, and then performing treatments such as undercutting the resist layer.
A method in which an insulating film is provided over the entire substrate, and finally the resist pattern is peeled off together with the insulating film (lift-off method); (3) By applying a resin such as a fluid photoresist onto a substrate having a thin film pattern. , a method of attaching a resin layer with a smooth surface; and a combination thereof.

However, method (1) requires high precision alignment to form a resist pattern complementary to the FIV11 pattern, and method (2) may damage the turns of the resist layer when etching the thin film. or
It is necessary to prevent deterioration in quality, and for this reason, there is a problem in that a high degree of skill and careful attention are required for its operation. Also.

The method (3) has the disadvantage that it is difficult to achieve sufficient surface flattening.

[Description of the Present Invention] As a result of extensive research aimed at solving the above-mentioned problems associated with conventional thin film surface planarization methods, particularly problems in manufacturing thin film magnetic heads, the present inventor has discovered the following: In the above lift-off method (2), by forming a resist pattern using an already formed thin film pattern as a photomask, surface flattening can be achieved easily and with high precision, and the above-mentioned problems can be solved. We have found that this can be achieved and have arrived at the present invention.

The present invention provides a method for flattening the surface of a substrate having irregularities formed by patterning an opaque or semi-transparent thin film provided on a transparent substrate, which includes: 1) forming a positive photoresist layer on the transparent substrate; 2) forming a resist pattern having the same shape as the pattern on the thin film pattern by exposing the transparent substrate to light from the back side, developing it, and removing the exposed portion of the photoresist; Steps of providing an insulating layer with the same thickness as the thin film pattern on the substrate; 8 and 3;
) removing the photoresist and insulating layer on the S film pattern using a resist removing liquid;

In other words, the method for flattening the surface Vl of the light beam 11 is transparent (
In order to solve the difference in unevenness caused by the opaque to translucent thin film pattern formed on the board, first, positive type),
After forming the + resist layer, the f11 film pattern is used as a photomask to expose the substrate to light from the rear surface and develop it to form a resist pattern identical to the ltJ IIIJ pattern. Next, after providing an insulating layer to fill the four parts of the unevenness, the resist is removed, thereby also removing the insulating layer on the resist pattern. Therefore, according to the present invention, it is possible to planarize the substrate surface with high accuracy without any need for complicated alignment corresponding to the thin 11-taper pattern on the substrate.

Furthermore, the resist pattern used in the lift-off method of the present invention is newly formed, and unlike the conventional lift-off method, the resist pattern used for forming the RH film pattern is not used. There is no damage or deterioration of the resist due to etching during etching, and lift-off can be performed with high precision in this respect as well.

The present invention will now be described in detail with reference to the accompanying drawings.

FIGS. 1(a) to 1(d) are diagrams illustrating the planarization process of the present invention. Of these, FIG. 1(a) shows opaque l31j to semitransparent # film patterns 2 on a transparent substrate I.
is attached to show a state in which irregularities are formed on the substrate surface.

The transparent substrate to which the planarization method of the present invention is applied is resistant to light such as ultraviolet rays that can cause chemical changes in the old photoresist layer (for example, solubilization of photoresist l[iF, etc.). An example of this is single crystal or polycrystalline sapphire (AMz
03), and crystalline or glassy SfO□.

Furthermore, since the thin film pattern formed on the transparent substrate is used as a photomask in the present invention, it must be opaque to light, and therefore it must be an opaque or semitransparent thin film pattern. is necessary. Examples of such thin film patterns include patterns of magnetic films such as Permalloy and Centast; and conductive films such as Au, Cu, and Au.

First, a positive photoresist is coated on the surface of a transparent substrate l on which a thin film pattern 2 is formed by using a method such as spin coating to provide a single layer 3 of photoresist. Next, a light beam such as ultraviolet rays (parallel light tM) is irradiated from the back surface of the substrate for exposure, solubilizing the portion of the photoresist c that does not overlap with the thin film pattern, and then developing, as shown in FIG. b) Opaque I as shown in
Only the photoresist on the JJ or translucent thin film remains.

That is, the opaque to translucent thin film pattern 2 serves as a photomask, and only the photoresist portions (exposed portions) that do not overlap with the pattern are solubilized, and then development processing is performed to dissolve the exposed portions of the photoresist. Only the resist pattern 3' is removed, and a resist pattern 3' identical to the thin, vague pattern is obtained.

Examples of the positive photoresist used in the present invention include quinone-diazide photoresist I. Specifically, commercially available AZ-based photoresists (AZ-1375, AZ-, 1350J, AZ-1
370, AZ-1350B; manufactured by Sibley Corporation).

Further, as the exposure source, light rays such as ultraviolet rays are used as described above.

The base of the resist pattern (lift material) thus formed is preferably subjected to an undercut treatment in order to facilitate the subsequent peeling process. The undercut treatment can be carried out, for example, by briefly immersing the substrate on which the photoresist layer is previously provided in a suitable organic solvent, such as chlorobenzene or toluene, before or after exposure. By immersing in the above solvent, the solvent and low molecular weight resin remaining in the part of the photoresist G near the surface are removed, so during subsequent development, the photoresist in this part is relatively The resulting resist pattern has a protruding upper part. Therefore, when an insulating layer is next provided, it is possible to prevent wraparound and avoid covering the edge portion.

Next, an insulating layer 4 is formed on the transparent substrate l by sputtering or the like to form an F! It is formed to have the same thickness as the film pattern 2 [FIG. 1(C)]. Here, it goes without saying that the film thickness of the thin film pattern and the "same layer thickness 1" may be approximately the same layer thickness, and the thickness of the thin film pattern and the top surface of the insulating layer formed on the four parts of the substrate may be approximately the same. It suffices if the height relationship with the upper surface is substantially flat.

An example of a material used for the insulating layer for filling the four parts of the unevenness is A-203.5502.

The resulting substrate is then treated with a resist removal solution to remove the photoresist. At the same time, the insulating layer on the resist pattern is also removed, and the recesses of the sM pattern 2 are filled with an insulating layer pattern 4' (inverted pattern), resulting in a flattened substrate surface, as shown in FIG. 1(d). It will be done.

Furthermore, if desired, a photoresist layer or a suitable resin layer, which also serves as an insulating layer, can be provided on the planarized substrate surface by coating, etc., so that the surface can be made even more highly planarized. Also, if desired, 5i0 may be applied to the surface of this substrate.
2. A film 203 or the like may be formed by sputtering, or the surface of the substrate may be etched by an ion beam or the like.

As explained above, according to the present invention, it is possible to eliminate irregularities caused by an opaque or semi-transparent thin film pattern formed on the surface of a transparent substrate with high precision without causing any positional deviation. The precision of thin lI2 formation and microfabrication is also increased.

Therefore, the present invention can be used in manufacturing methods that require fine pattern processing techniques for the aforementioned thin-film magnetic heads, semiconductor elements, etc., and in particular, in manufacturing thin-film magnetic heads, a magnetic film is used as the lower magnetic pole. It can be suitably used when flattening the surface of a substrate on which a thin film pattern is formed.

[Brief explanation of the drawing]

FIGS. 1(a) to 1(d) are cross-sectional views illustrating the planarization process of the present invention. 1: Transparent substrate, 2: Non-transparent to semi-transparent thin film pattern, 3: Positive photoresist layer, 3°: Photoresist pattern, 4: Insulation #+': Insulating layer pattern Patent applicant: Fuji Photo Film Co., Ltd. Agent Patent Attorney Yasuo Yanagawa Figure 1

Claims (1)

[Claims] l. In a method for flattening the surface of a transparent substrate on which an opaque or translucent thin film pattern is provided and an uneven surface is formed, ii) a positive photoresist layer is provided on the transparent substrate. After that, a step of forming a resist pattern having the same shape as the pattern on the thin film pattern by exposing the transparent substrate from the back side, developing it, and removing the photoresist in the exposed area; 2) a step of providing an insulating layer with the same thickness as the thin film pattern on the substrate; and 3
1.) A method for planarizing the surface of a substrate with a thin film pattern, the method comprising: removing the photoresist and insulating layer on the thin film pattern using a resist removal solution. 2. The surface flattening method according to claim 1, wherein in the step 1), an undercut treatment is performed on the base of the resist pattern on the thin film pattern. 3° In step 2) above, an insulating layer with the same thickness as the thin film pattern attached on the substrate is formed. The surface flattening method according to claim wS1, characterized in that it consists of A-203 or 5i02. 4. Claim 1, characterized in that the flattened substrate surface is further provided with an insulator 11 to smooth it.
Surface flattening method described in Section 2. 5゜The above transparent substrate is a substrate for a thin film magnetic head,
The surface flatness according to any one of claims 1 to 4, wherein the opaque to semitransparent S film pattern is a patterned magnetic film or conductive film. method.