JPS61222010A - Flattening method - Google Patents

Abstract

PURPOSE:To obtain an extremely flat surface regardless of a pattern size by subjecting the resist surface formed by embedding the recesses on the surface of an insulating layer having ruggedness with a dummy resist and coating further the resist thereon to ion incidence at two stages of angles. CONSTITUTION:A lower magnetic layer 13, a conductor layer 11 and an insulating layer 15 are successively formed on a substrate 14 and since the surface is made rugged by underlying conductor coils, the photoresist 16 is coated in the recesses thereof and the resist 17 is further coated thereon to embed the small recesses of the resist 16. The resist 16 is heat-treated at >=200 deg.C to prevent the melting with the resist 17. The ions are made incident at 30-45 deg. angle to the surface of the resist 17 to prevent the generation of the ruggedness on the surface. The SiO2 of the layer 15 and the resist are etched at the same speed and 75 deg. ion incident angle and thereafter a magnetic layer 18 is formed. The recording and reproducing efficiency is thus improved by two stages of etching for flattening.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for planarizing the surface of an insulating layer having irregularities using ion etching.

(Prior art) For example, in a thin film magnetic head, before the formation of the upper magnetic pole, the coil conductor has unevenness, so the insulating layer formed by sputtering etc. on the coil conductor becomes uneven due to the influence of the unevenness of the underlying coil conductor. It is formed. Therefore, the magnetic material (for example, sendust or amorphous) formed thereon by sputtering or the like also has irregularities, which reduces the magnetic permeability of the magnetic material and reduces the recording and reproducing efficiency of the magnetic head. Therefore, flattening treatment is usually performed to remove these unevenness.

The steps shown in FIGS. 3(a) to 3(e) are a conventional method for planarizing the insulating layer of a thin m magnetic head. That is, the lower magnetic layer 3 is formed on the substrate 4 by sputtering or vapor depositing a magnetic material such as sendust or amorphous. Furthermore, a first insulating layer 2 made of 5iOz or the like is formed thereon. And on top of that
A conductor layer made of A9J or A9J is formed, and a coil conductor 1 is formed using ion etching or the like (Fig. 3(a)).
). A second insulating layer 5 made of SiO2 or the like is provided thereon.
is formed by sputtering or vapor deposition (FIG. 3(b)). After that, the photoresist 6 is applied to a thickness sufficiently thicker than the step of the second insulating layer (FIG. 3(C)), and the ion incidence angle at which the etching rate of the photoresist 6 and the second insulating layer 5 are the same (what is the ion incidence angle? (This refers to the angle formed by the ion beam and the normal to the sample surface.) to obtain a relatively flat insulating layer 5 (Fig. 3(d) 4).
figure). Note that FIG. 4 is an enlarged view of a part of FIG. 3(d). After this, a magnetic material 7 made of sendust, amorphous, etc. is finally formed on this insulating layer 5 by sputtering, vapor deposition, etc. (Fig. 3 (e))
)L However, when flattening using the above method, the amount of unevenness varies depending on the pattern size, and large patterns are hardly flattened. FIG. 5 shows the amount of unevenness after coating the photoresist with respect to the pattern size. This has a step height of 2 μm, a pattern width and a space of W.
This figure shows the unevenness 1a on the surface of the photoresist after coating the photoresist to a thickness of about 8 μm on the unevenness of um. As is clear from FIG. 5, the degree of relaxation of the unevenness of the underlying layer depends on the pattern size, and as the pattern size increases, there is no relaxation of flatness at all, and even after etching, the surface of the insulating layer still has unevenness.

Further, when flattening etching is performed, the ion incidence angle θ at which the S t Oz and the photoresist are etched at the same rate is 75°, as shown in FIG. When flattening etching is performed at such an ion incidence angle θ, since this angle θ is larger than the ion incidence angle of 55″ at which the maximum etching rate of the photoresist is obtained, minute impurities on the photoresist surface become nuclei. The etched photoresist is re-attached to these nuclei, or the etched photoresist is re-attached and re-polymerized to the photoresist surface due to diffusion.As a result, protrusions (8A18B) are formed during photoresist etching. be done.

In this state, the insulating layer S! As the etching speed of 7iOz is equal to that of 5i02, the protrusions of the photoresist are transferred onto the 5iOz, and countless protrusions are formed on the insulating layer to be planarized, reducing the planarization effect. There is a problem.

(Figure 4) (Object of the Invention) The present invention was made to solve the above problem, and its purpose is to provide a flattening method that can obtain an extremely smooth surface regardless of the pattern size. That is.

(Structure of the Invention) The planarization method of the present invention is to apply a photoresist with the same thickness as the unevenness on the surface of an insulating layer having unevenness, butterify the resist, fill the depressions with a dummy resist, and replace the dummy resist with the same thickness as the unevenness. heat-treating, then applying an upper resist on the surface filled with the dummy resist, heat-treating the resist, and etching the resist surface first at an ion incidence angle smaller than an ion incidence angle at which a maximum etching rate of the resist is obtained; Next, etching is performed at an ion incidence angle that makes the etching rates of the resist and the insulating layer equal.

(Example) An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram illustrating the manufacturing process of a thin film magnetic head according to the present invention. For example, in a WjII magnetic head, the lower magnetic layer 13 is formed on the substrate 14 by sputtering or evaporation of sendust or amorphous, and then the conductor layer 11 made of Cu, A9J, etc. is formed by sputtering or evaporation (see Fig. 1). (a)). Furthermore, an insulating layer 15 made of SiO□ or the like is formed thereon using the same method (FIG. 1(b)). In this case, the insulating layer 15 becomes a layer having irregularities due to the influence of the irregularities of the underlying conductor coil. After that, apply the photoresist 16 in the same way as the uneven surface ^
Apply only the thickness of 10 minutes, then butter it and apply it to the recessed area.
An optical resist 16 is formed (FIG. 1(C)). Further, an upper resist 17 is coated on top of this resist 16, but at this time, heat treatment is performed at 200° C. or higher to prevent the resist 16 from dissolving into the upper resist 17. In this case, if the temperature of the heat treatment is less than 200°, the upper and lower resists will melt together, making it impossible to fill the recesses and making it impossible to apply the resist evenly.

Furthermore, an upper resist 17 is applied on top of this to fill in the small recesses created by the dummy resist 16 (see Fig. 1).
d)). At this time, if the thickness of the upper resist 17 is 4 μm or more, the unevenness can be made flat regardless of the pattern size.

After the upper resist 17 formed in this way is heat-treated at 130°C or higher, the upper resist surface is first etched by ion milling at an ion incident angle θ greater than 30° and smaller than 45° (see Fig. 1 (e). )). The reason for heat treatment at 130°C or higher is that the photoresist is
If heat treatment is performed at a temperature lower than 30°C, thermal decomposition of the photoresist will not proceed completely, and as a result, when etched by ion milling, there will be a mixture of fast etching parts and slow etching parts, and flattening etching will continue as it is. This is because as time goes on, unevenness will occur in the resist, and this unevenness will be directly transferred to the insulating layer 15 made of S t Oz, and the planarization effect will be lost.

In addition, the ion incidence angle θ is larger than 30° and is 45°.
The reason for etching at a smaller angle is as follows. That is, as shown in Fig. 2, when the ion incidence angle θ is relatively small, for example 20°, the photoresist becomes a conical depression with a depth of about 0.8 μm and a diameter of about 10 μm, and when the ion incidence angle θ is As the size increases, the depth of the conical recess gradually becomes shallower, and when the ion incidence angle θ is, for example, 35°, the depth of the recess is about 0.2 μm. Further, when the ion incidence angle θ is 45°, both unevenness exists, and at an angle of 45° or more, most of the unevenness becomes a conical protrusion with a height of about 2 μm and a diameter of about 10 μm. In addition, these protrusions only occur when etching is performed for a long time, and the protrusions are rarely observed even after several tens of minutes of etching time.

Therefore, first, etching is carried out for several hours at an ion incidence angle θ greater than 30' and smaller than 45 degrees, and then etching is carried out for several minutes at an ion incidence angle θ 75 degrees at which the etching rates of SfOg and resist are the same. Thereafter, a sendust or amorphous magnetic layer 18 is formed by sputtering, vapor deposition, etc. (FIG. 1(f)).

Although the above-mentioned embodiment describes the case where the present invention is applied to a 1llll magnetic head, similar effects can be obtained even when the present invention is applied to semiconductors and other devices that require planarization. .

(Effects of the Invention) As explained above, according to the planarization method of the present invention, the first
The unevenness on the photoresist surface is made into extremely shallow depressions by the stepwise planarization etching, and then the photoresist and the insulating layer are etched at the same speed by the second step of planarization etching, so that the etched insulating layer is Regardless of the pattern size of the unevenness, a smooth surface without any protrusions can be obtained.

Furthermore, since the amount of unevenness of sendust or amorphous magnetic material formed by sputtering or vapor deposition on such a completely flat insulating layer is suppressed to within 0.5 μm, the magnetic permeability of the magnetic material is less likely to decrease. do not have. Therefore, the remarkable effect of improving the recording and reproducing efficiency of the head can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the processing process of a thin film magnetic head according to the present invention. FIG. 2 is a diagram showing the ion incidence angle and the size of the protrusion.
Fig. 3 is a diagram showing the processing process of a conventional thin film magnetic head, Fig. 4 is a partially enlarged view of Fig. 3(d), and Fig. 5 is a pattern size when the amount of unevenness is 2 μm and the unevenness after resist coating. FIG. 6 is a diagram showing the dependence of etching rate of 5fOz and photoresist on ion incidence angle. 11... Coil conductor 12... Insulating layer 13...
Lower magnetic layer 14... Substrate 15... Insulating layer 16... Photoresist 17... Upper resist Figure 1 Figure 2 Angle ec1) Figure 4 (JJITI)
(W) Ha Koon Kantaku

Claims (2)

[Claims] (1) A step of forming an insulating layer to be flattened on a surface with unevenness caused by a conductor, etc., applying a photoresist of approximately the same thickness as the unevenness on the insulating layer, and patterning the resist. a step of filling the recesses appearing on the surface of the insulating layer with a dummy resist and heat-treating the dummy resist; and a step of applying an upper resist on the surface of the insulating layer filled with the dummy resist and heat-treating the upper resist. and etching the upper resist from the surface at an ion beam incidence angle smaller than an ion beam incidence angle that provides a maximum etching rate of the upper resist, and then etching at an ion incidence angle that makes the etching rates of the resist and the insulating layer equal. A flattening method consisting of a process. (2) forming the insulating layer with SiO_2, heat-treating the dummy pattern of the resist filling the unevenness at 200°C or higher, then heat-treating the upper resist at 1.30°C or higher;
The planarization method according to claim 1, further comprising the steps of: next performing ion milling at an ion incidence angle greater than 30° and smaller than 45°; and finally ion milling at an ion incidence angle of 75°. .