JPS6032323A - Method for flattening of sio2 insulated layer surface - Google Patents

Abstract

PURPOSE:To enable to accomplish flattening of the surface of an SiO2 insulating layer in a highly accurate manner by a method wherein quirone-diazide photoresist is used as a plane-forming resin, and an etching is performed on the obtained planeface using ion milling at the incident angle of the prescribed range. CONSTITUTION:After quinone-diazide photoresist has been coated by performing a spin coating on the SiO2 insulating layer 33 having the stepping corresponding to a stepping formed by a lower magnetic pole 34 and a conductive part, it is dried up and a photoresit layer 34 is formed on a substrate. The photoresist layer 34 formed as above has the plane face in the amount of surface irregularity h1 of 0.3mum or below. Then, an etching is performed on the concavity located on the surface of the photoresist layer 34 and the insulating layer 33. Said etching is conducted using an ion beam. The incident angle of an ion beam is to be brought within the range of 60-80 deg. against the perpendicular line on the surface of the photoresit layer 34.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for planarizing the surface of an SfO□ insulating layer, and in particular to a method for planarizing the surface of an SfO□ insulating layer, and in particular to a method for planarizing the surface of an SfO
The present invention relates to a method suitable for planarizing the surface of an insulating layer.

In recent years, magnetic circuits, semiconductor circuits, and the like have been provided on substrates by forming thin film patterns using photolithography technology. For example, thin-film magnetic heads for magnetic recording used in magnetic recording devices such as VTRs, digital audio tape devices, and magnetic disk devices, and semiconductor devices such as solid-state image sensors for converting optical signals into electrical signals are as described above. These magnetic heads, semiconductor elements, etc. are desired to be smaller and have higher performance as the above-mentioned magnetic recording devices become smaller. Since it is desired to record on a recording medium at a high density, development of a magnetic head with a narrow gap length and narrow track width is required.At the same time, a magnetic head is also required to have a high magnetomotive force. Therefore, the magnetic circuit needs to have high efficiency.

In the manufacture of magnetic circuits or semiconductor circuits as described above, a large number of thin film circuit patterns are formed on the surface of the substrate.
It is laminated on a substrate by sequentially performing thin film formation and microfabrication such as etching. Note that an insulating layer is generally provided between these thin film circuit patterns. In this manufacturing process, steps, that is, irregularities, are formed on the surface of the insulating layer in accordance with the thin film pattern formed inside or under the insulating layer. The unevenness thus formed on the surface of the insulating layer causes a decrease in the lithography accuracy of the thin film pattern formed thereafter, and further brings about a deterioration in the quality of the obtained circuit.

For example, a thin film magnetic head for magnetic recording basically has a lower magnetic pole and an upper magnetic pole made of a magnetic film such as permalloy or sendust on a substrate such as glass or sapphire, and a conductive film such as Cu between them. It has a structure in which a coil consisting of is provided with an insulating layer interposed therebetween. A magnetic head is manufactured by first forming a thin film pattern of a magnetic material film on the above-mentioned substrate by etching to form a lower magnetic pole, then providing an insulating layer made of 5i02 or the like, and then forming a thin n-ta pattern (coil pattern) of a conductive film. It is manufactured by forming by etching and further providing a thin film pattern (upper magnetic pole) of an insulating layer and a magnetic film.

In manufacturing this magnetic head, if an insulating layer such as Si02 and a magnetic film are directly formed by sputtering or the like on a thin film pattern of a conductive film that will become a coil, the difference in level caused by the thin film pattern of the conductive film may be Since it is also formed in the insulating layer and the upper magnetic film as it is, unevenness corresponding to the pattern of the conductive film appears on the surface of the obtained upper magnetic material (2). The unevenness of the upper magnetic pole tends to increase the magnetic resistance of the resulting magnetic head, and the distance between the upper magnetic pole and the lower magnetic pole is partially shortened in the four parts, resulting in leakage of magnetic flux. This causes a problem of lowering head efficiency (recording/reproducing efficiency).

The step created by the thin film pattern (lower magnetic pole) of the magnetic film provided on the substrate is also reproduced as is when an insulating layer such as Si02 is provided thereon by sputtering or the like. Therefore, when the conductive film is etched next to form a coil pattern, etching failures tend to occur at the rising portions of the steps, making it difficult to form the coil pattern with high precision. Furthermore, when a photoresist film is provided on the magnetic film to form a coil pattern, the thickness of the photoresist film differs between the top and bottom of the step caused by the bottom magnetic pole.
The problem is that the coil pattern obtained by etching tends to be tapered at the top of the step, and the coil tends to be fused at the tapered portion when energized.

Therefore, by using the thin film circuit pattern as described above, 5
To eliminate the unevenness that occurs on the surface of the insulating layer such as i02,
It is essential in manufacturing thin film magnetic heads.

In order to solve this problem, various methods have been developed to flatten the insulating layer formed on the thin film pattern. The so-called lift, off method, gill, chippatsu method, etc. have been proposed. However, when the above-mentioned resin is used as the insulating layer, there are problems in that the heat treatment temperature for improving the properties of the magnetic film or the heat treatment temperature for adhering the protective substrate to the glass cannot be adjusted, and the magnetic There is a problem that resin seeps out due to weak adhesion to body membranes.

For example, in the lift-off method, a layer consisting of an insulator layer such as SiO2 and a lift material is first formed, a fine pattern is formed by etching to form four parts, and then a conductive material (or magnetic material) is formed on the four parts and the lift material layer. ) coated with
This method then removes (lifts off) the lift material layer and the conductor film (or magnetic film) thereon using a release agent, thereby obtaining a flat surface patterned with insulators and conductors. With this method, it is difficult to form a perfect plane because a V-shaped groove is created between the insulator and the conductor, and the process for removing the lift material is complicated. There are drawbacks.

Furthermore, the etch pack method is a method in which a resin is applied onto an insulating layer having irregularities to make it flat, and then the resin layer and the insulating layer at the convex portions are removed by etching. Conventionally, this method has had the problem of difficulty in etching the resin layer and the insulating layer equally. That is, it is difficult to select a resin such as a photoresist that can be etched at the same speed as the insulating layer, and to set etching conditions. Plasma etching or reactive ion etching using scum such as CF4+ (, Q2, BCl3 or Ar+02) is known as a method for etching the resin layer and the insulating layer at the same speed. It is not easy to set the speeds to the same level, and there are problems such as the gas used is toxic or corrosive, and the gas source needs to be adjusted with high precision. No Ar+0
Even if 2 is used, the problem of requiring highly accurate adjustment of the waste source cannot be avoided.

The inventor of the present invention has conducted extensive research aimed at solving the above-mentioned problems associated with conventional fine pattern processing techniques, particularly problems in manufacturing thin-film magnetic heads. We have discovered that the above problems can be solved or reduced by using a quinone diazide photoresist as the forming resin and etching the resulting plane by ion milling at a specific range of incident angles. , arrived at the present invention.

The present invention provides a method for planarizing the surface of an insulating layer made of Si02 having an uneven surface, including: 1) attaching a quinone diazide photoresist layer to the uneven surface of the insulating layer to flatten the surface of the insulating layer; A method for planarizing the surface of a SiO□ insulating layer, comprising: forming a surface; and 2) performing ion beam etching on the surface of the photoresist layer at an incident angle in a range of 60 to 85 degrees. It provides:

According to the planarization method of the present invention, the surface of the SiO□ insulating layer can be planarized with high accuracy without any need for complicated alignment corresponding to the thin film pattern to be formed.

When using the above-mentioned polyimide resin to form the etched surface, multiple coatings and heat treatments are required, whereas in the present invention, when forming the etched surface using a quinone diazide photoresist, Coating and heat treatment only need to be performed once, thus simplifying the process of forming the etched surface. By using this photoresist and performing ion beam etching at the above-mentioned incident angle, the photoresist and 5i02 can be etched at approximately the same speed.

Furthermore, the method of the present invention does not require complicated steps like the lift-off method, nor does it require sophisticated technology.

Furthermore, by using an inert Ar + ion beam as the ion beam, the present invention solves the conventional problems such as the use of toxic or corrosive gases and fine adjustment of the gas with high precision. It is also possible.

Therefore, the method for planarizing the surface of the 5i02 insulating layer of the present invention is as follows:
This is a method for eliminating unevenness formed on the surface of an insulating layer made of SiO□, and can be used in manufacturing methods that require fine pattern processing technology for the aforementioned thin film magnetic heads, semiconductor elements, and the like.

Next, the present invention will be explained in detail using a thin film magnetic head as an example.

FIG. 1 is a partial plan view showing an example of a thin III magnetic head according to the present invention. In FIG. 1, the thin film magnetic head consists of a magnetic pole 2, a coil 3, and a conductive part 4 provided on a substrate l.

2(a) is a partial sectional view taken along line AA in FIG. 1, and FIG. 2(b) is a partial sectional view taken along line BB in FIG. 1. In FIG. 2(a), the thin film magnetic head includes a lower magnetic pole 12, a conductive part 13, and an insulating layer 14 of 5i02 provided on a substrate 11, and a coil 15 further provided thereon.
, an insulating layer 16 of SiO2, an insulating layer 17 constituting a cap section, and a V section magnetic pole 18.

In addition, in FIG. 2(b), the substrate 21, the lower magnetic pole 22
．． It is composed of an insulating layer 23 of 5i02, a coil 24, an insulating layer 25, and an upper magnetic pole 26.

A thin film magnetic head can be manufactured using the planarization method of the present invention, for example, by the method described below.

First, as shown in FIGS. 2(a) and 2(b), permalloy (Ni@Fe alloy), Centast (AM-FeφSt alloy), amorphous magnetic alloy, etc. A magnetic film is formed by sputtering or the like. The thickness of the magnetic film is usually 2
~5gm.

After spreading a positive photoresist on this magnetic film,
A resist layer with a desired pattern is formed by exposure and development using a positive photomask. Next, the magnetic film is patterned by etching and removing the resist layer, thereby forming the lower magnetic pole 12 (22). The magnetic pole thus obtained has, for example, a thickness of about 3 gm, a width of 50 gm and a length of 200 lm.

In addition, after forming a conductive film made of A, Cu, Au, etc. on the substrate, etching is performed in the same manner as above.
A conductive portion 13 is formed.

Next, Si02 is deposited on the entire surface of the substrate by sputtering or the like.
An insulating layer 14 (23) is provided.

The obtained insulating layer has a level difference as shown in FIG. 3(a) corresponding to the level difference due to the lower magnetic pole and the conductive part [31: substrate, 32: lower magnetic pole, 33: insulating layer]. However, FIGS. 3(a) to 3(c) are cross sections 1j for explaining the planarization process of the present invention.

In order to eliminate this level difference, the 5i02 insulating layer is planarized. First, a photoresist according to the invention is applied by spin coating.

The quinone-diazide photoresist used in the present invention is already known, and specific examples thereof include AZ-
AZ such as 1350J, AZ-1370, AZ-1375, etc.
-1300 series; and AZ-1450J, AZ-
Examples include quinone e-diazide photoresists belonging to the AZ-1400 series (manufactured by Hoechst Co., Ltd.) such as 1470 (7).

The photoresist spin coating is preferably carried out at a rotation speed of 500 to 11,000 rpm and a rotation time of 10 to 300 seconds. Particularly preferably, the number of revolutions is 5.
00 to 700 rpm, and rotation time is 200 to 300 seconds. After coating, it is dried to form a photoresist +-e on the substrate. The layer thickness of the photoresist layer varies depending on the level difference on the surface of the insulating layer and its width, but generally the level difference is 0.5~
If it is in the range of 8 gm, it is preferably in the range of 1 to 20 pm.

As shown in FIG. 3(b), the formed photoresist layer has a surface unevenness amount (height difference of unevenness: hl) of 0.3 gm.
It has the following plane [31: substrate, 32: lower magnetic pole, 3
3: insulating layer, 34: photoresist layer].

Next, the convex portions on the surfaces of the photoresist layer and the insulating layer are etched. Etching is performed by ion milling, ie, ion beam etching.

In the present invention, inert Ar gas is particularly preferably used since it is non-toxic and non-corrosive. however,
The gas used in the present invention is not limited to the above-mentioned inert Ar gas.

The ion beam is obtained as an inert Ar+ ion beam, for example, by exciting an inert Ar gas with thermoelectrons under high voltage. The quinone diazide photoresist and 5iOz are etched by irradiating the surface of the photoresist layer with this ion beam. However, in the present invention, the incident angle of the ion beam is set so that the etching/nching speeds for the photoresist and 5i02 are as equal as possible, so that the photoresist part and the 5i02 part are etched to the same thickness. In addition, the angle should be in the range of 60 to 85 degrees with respect to the normal to the surface of the photoresist layer.

The surface of the SiO3 insulating layer obtained by etching is
As shown in Figure (c), the height difference (h2) between the bottom surface of the four parts and the top surface of the convex part can be a plane of 0.3 gm or less [31. Substrate, 32: Lower magnetic pole, 35:
Insulating layer].

The SiO□ insulating layer 14 whose surface has been flattened in this way
(23) is further etched into a pattern of a given ψ, and then a conductive film of Cu, AM, Au, etc. is provided thereon by sputter linking. By patterning this conductor film using the above-mentioned positive photoresist,
Thickness 1~5gm, line width 3~20lm and coil spacing 3
Form a coil 15 (24) of ~20 gm.

Next, the 5i02 insulating layer 16 (25
) has irregularities corresponding to the irregularities of the coil. Therefore, by applying the above-described planarization method of the present invention to the surface of this SiO2 insulating layer, the surface of the insulating layer is planarized.

Furthermore, after patterning this Ii layer,
In order to provide a gap between the cores of the magnetic head, an insulating layer 17 such as 5i02 is provided and patterned. Finally, we deposited a magnetic film made of the same material as in the relo.
, the upper magnetic pole 18 (26) is formed by etching into a desired pattern.

In this way, in the manufacturing process of thin film magnetic heads, S
By flattening the surface of the i02 insulating layer, etching defects will not occur during pattern processing in subsequent steps, and a magnetic head with excellent head efficiency can be obtained.

The method for planarizing the SIO2 insulating layer of the present invention is not only used in the production of thin film magnetic heads as described above, but also widely used in fields that require thin film technology and microfabrication technology, such as the production of semiconductor elements. It is something that can be done.

Examples of the present invention will be described below.

[Example] (1) Preparation of sample An An thin film was formed by sputtering on a sapphire substrate (thickness: 2 mm, diameter: approximately 5 cm). After applying a positive photoresist (AZ-1350J, manufactured by Hoechst) on this thin film, it is exposed and developed using a positive photomask, and patterned by etching and nitching to create irregularities corresponding to the coil. was formed. The obtained unevenness has a convex thickness of 2.7 gm and a line width of 20 gm.
and the interval therebetween was 20 pm.Next, 5i02 was formed into a film by sputtering on this substrate to provide an insulating layer having a layer thickness of 4.7 pm.

(2) Flattening of the surface of the Si02 insulating layer First, a quinone-diazide photoresist (AZ-1375; manufactured by Hoechst Co., Ltd.) was spin-coated on the surface of the 5i02 insulating layer of the above sample at a rotation speed of 580 rpm for 270 seconds. After coating, 130°C
Baking was performed at a temperature of 30 minutes to form a photoresist layer having a layer thickness of 8.5 pm on the four parts of the insulating layer.

The amount of unevenness on the surface of the photoresist layer obtained was measured using a stylus-type film thickness meter (stylus pressure: 10 mg, radius of curvature of the needle = 125 gm). As a result, the amount of surface unevenness was 0.15 m.

Next, an Ar+ ion beam generated by a Kauffman ion source using an inert Ar gas is applied to the surface of this photoresist layer at an angle of 70 degrees (angle with respect to the normal to the surface).
Ion beam etching was carried out by injecting the ion beam into the ion beam. Etching is performed at an initial vacuum level of 1, 5X 10-'Torr.
Above, the degree of vacuum after introducing Ar gas is 5 x 10-'Tor.
r, ion acceleration voltage 0.95KV, ion current electric potential 0.
The test was carried out under the conditions of 58 mA/Cm' and an enquenching time of 170 minutes.

The amount of unevenness on the surface of the obtained insulating layer was measured using a SEM cross-sectional photograph. As a result, the layer thickness in the Au recess of the insulating layer was 4
．． 2 gm, and the amount of surface unevenness was 0.2 m.

Next, SiO□ was formed on the sapphire substrate to a thickness of about 51 Lm by sputtering, and the photoresist AZ-1375 was applied thereon to a thickness of about 8 Bm by spin coating. After that, a part of the photoresist is removed by exposure and development.
The surfaces of the two layers were exposed and baked at a temperature of 130°C for 30 minutes. Ion beam etching was performed on the sample thus prepared under the same conditions as above, except that the incident angle of the Ar+ ion beam incident on the surface of the photoresist layer was varied in the range of 0 to 85 degrees. Ta. The results obtained are shown in graphical form in FIG.

FIG. 4 is a graph in which the horizontal axis represents the incident angle of the ion beam, and the vertical axis represents the etching rate ratio between the photoresist and 5i02.

As is clear from the results shown in FIG. 4, it was found that when the incident angle of the Ar+ ion beam was in the range of 60 to 85 degrees, the etching rate ratio was 0.85 or more. By etching the quinone diazide photoresist and 5i02 at an etching speed ratio within this range, the surface of the resulting 5i02 insulating layer has a sufficiently flat surface with an amount of unevenness of 0°3 gm or less. Become.

As explained above, according to the present invention, it is possible to obtain a surface that is extremely gently flattened, thereby increasing the accuracy of subsequent thin film formation and microfabrication. Furthermore, the resulting thin-film magnetic head has an extremely precise planar structure.1. It becomes C.

Since it has a planar structure, it is easy to create even a multilayer structure head, and since there are no recesses, there is no magnetic flux leakage at the convex part of the upper magnetic pole, which was a problem in the past, and the head is efficient. becomes significantly better. In addition, since a single gas is used, there is no need for troublesome partial pressure adjustments, making it easy to control, and the gas is non-corrosive), significantly improving the reproducibility and reliability of the planarization process. can.

[Brief explanation of drawings]

FIG. 1 is a partial plan view showing an example of a thin film magnetic head. 2(a) is a partial sectional view taken along line AA in FIG. 1, and FIG. 2(b) is a partial sectional view taken along line BB in FIG. 1. FIGS. 3(a) to 3(C) are cross-sectional views illustrating the planarization process of the present invention. 1: Substrate, 2: Magnetic pole, 3: Coil, 4: Conductive part 11: Substrate, 12: Lower magnetic pole, 13: Conductive part 14:
Si02 insulating layer, 15: coil, 16: SiO□ insulating layer, 17: insulating layer constituting the gap portion, 18 two upper magnetic poles 21: substrate, 22: lower magnetic pole, 23: SiO□ insulating layer,
24: coil, 25: insulating layer, 26: upper magnetic pole 31; substrate, 32: lower magnetic pole, 33: insulating layer 34: photoresist layer, 35: insulating layer In Figure 4, the incident angle of the ion beam is plotted on the horizontal axis. photoresist and 5i0 on the vertical axis.
Work with 2 1. FIG. 3 is a diagram showing the relationship when taking the switching speed ratio. No. 1, No. 1, “A, 2nd parable; Figure 3 (c)

Claims (1)

[Claims] A method for planarizing the surface of an insulating layer made of 5i02 having a 1° surface unevenness, comprising the steps of: 1) attaching a quinone diazide photoresist layer to the uneven surface of the insulating layer; 2) performing ion beam etching on the surface of the photoresist layer at an incident angle in the range of 60 to 85 degrees; method. 2. The method for planarizing the surface of a SiO'2 insulating layer according to claim 1, wherein the ion beam etching is performed using an inert Ar scum. A patent characterized in that the level difference of the unevenness on the surface of the SiO□ insulating layer in the 3° flattened portion is in the range of 0.5 to 8 gm, and the layer thickness of the photoresist layer is in the range of 1 to 20 gm. A method for planarizing the surface of a SiO2 insulating layer according to claim 1. 4゜The 5i02 insulating layer having the above-mentioned unevenness is provided on a substrate for a thin film magnetic head, and is characterized by being any of the insulating layers of Claims 1q+ to 3. A method for planarizing the surface of a SiO□ insulating layer according to claim 4. The S i0 according to any one of claims 1 to 3, wherein the 5i02 insulating layer having the unevenness of 6° and 0 is provided on a substrate for a semiconductor element.
2. Method for flattening the surface of the insulating layer.