JP2000353305A - Method of etching organic film, production of magnetic head and magnetic head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the accuracy of microfabrication of an organic film while suppressing the damages to a mask to the minimum by using CO2 as a plasma gas without adding a halogen gas. SOLUTION: Permalloy 40 as the lower structure of a magnetic head and the seed for plating is formed on an AlTiC substrate, and a photoresist 46 is applied thereon to form a groove pattern by photolithography. Then the photoresist 46 is used as a mask to etch a silicon oxide film 44 in a lower layer. Then the silicon oxide film 44 is used as the mask to etch a resist 42 in the lower layer with plasma. The photoresist 46 as the uppermost layer is removed by etching. Since CO2 is used as the plasma gas without containing halogen elements such as fluorine, the lower silicon oxide film 44 is not etched. As a result, the lower resist 42 is further etched while the silicon oxide film 44 acts as the mask.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for etching an organic film formed on a substrate by using plasma. Further, the present invention relates to a method of manufacturing a magnetic head using the etching technique and a magnetic head.

[0002]

2. Description of the Related Art Conventionally, there has been the following method for etching an organic film formed on a substrate. (1) Perform plasma etching with O ₂ gas. (2) As disclosed in Japanese Patent Application Laid-Open No. 10-125559, the anti-reflection film is subjected to plasma etching with O ₂ / CO gas. (3) As disclosed in JP-B-2-37091, the organic film is formed of CF ₄ / CO ₂ gas (CO ₂ is 65 to 8).
5%). When CF ₄ / CO ₂ is used as an etching gas, there is a merit that the selectivity with respect to Si is ten times that in the case where CF ₄ / O ₂ is used.

On the other hand, in a method of manufacturing a magnetic head, when a permalloy (NiFe) magnetic pole (width: 0.5 μm, height: 4 μm) of a magnetic head for a hard disk is formed by plating, a plating die is prepared in advance. As the plating die, an organic film that can be easily removed by an ashing device is used in order to avoid damage to the magnetic pole of permalloy when the plating die is removed. Conventionally, when forming a plating mold as described above, a resist is used as an organic film, and the plating mold is directly formed on the photoresist by photolithography (4).

[0004]

However, the above-described conventional organic film etching method and magnetic head manufacturing method have the following problems.

[0005] (1) When the O plasma etching an organic film using a ₂ gas, although O ₂ gas plasma resist simply be removed (ashing) can, be subjected to anisotropic etching using the etching mask It is difficult. That is, since the incident direction of the oxygen radicals on the substrate cannot be controlled by the RF bias, the etching proceeds in the lateral direction immediately below the mask, and the etching becomes larger than a predetermined dimension.

(2) When the organic film is plasma-etched with O ₂ / CO gas, the etching proceeds in the lateral direction immediately below the mask, and a predetermined dimension cannot be obtained. Also, the etching rate is low. In particular, when the thickness of the organic film serving as the material to be etched is large, such as when used in a manufacturing process of a magnetic head, the above-described problem becomes significant.

(3) The organic film is made of CF₄/ CO₂Plastic with gas
When the zuma etching is performed, CF ₄By mask and
Used silicon oxide mask is etched
Therefore, there is a problem that a predetermined shape cannot be obtained.

(4) With the increase in the capacity of the hard disk,
As the recording density increases, the width of the magnetic pole at the tip of the magnetic head (the part where information is written to the magnetic material) becomes narrower (0.5 μm or less), and it becomes difficult to form the magnetic head by photolithography. Is coming. In addition, the height of the magnetic pole of the magnetic head, which is as high as about 4 μm, makes it more difficult to form a plating die by photolithography. That is, in the method of directly patterning a photoresist by the photolithography technique, it is difficult to expose a fine pattern when the film thickness is 2 μm or more and the width is 0.5 μm or less. Head part and coil part like a magnetic head
If the thickness of the exposure lens is greatly different from that of the photoresist, it is difficult to perform appropriate exposure in both portions. Further, according to the photolithography technology, there is a problem that processing other than the photosensitive material cannot be performed as a matter of course.

SUMMARY OF THE INVENTION The present invention has been made in view of the above situation, and an object of the present invention is to improve the fine processing accuracy of an organic film while minimizing damage to a mask in an organic film etching method. This is the purpose of 1.

[0010] In the method of manufacturing a magnetic head, fine processing (0.5 μm or less in width) at the tip of the magnetic head.
It is a second object of the present invention to improve the accuracy of.

It is a third object of the present invention to provide a magnetic head having a fine magnetic head tip processed with high precision.

[0012]

The organic film etching method according to the present invention uses CO ₂ as a plasma gas and does not mix a halogen gas. By using CO ₂ as the plasma gas, the etching anisotropy of the organic film is improved, and precise processing becomes possible. This is particularly effective when etching a thick organic film. Further, since a halogen gas is not mixed with the plasma gas, etching of the mask (silicon oxide film or the like) can be prevented.

In the above etching method, the CO₂Plastic
Zumagas, CO, O₂Mix one or both of
May be. By adding CO, the etching layer
Although the etching rate is slightly reduced, more accurate etching is performed.
I can do it. Also, CO ₂To O₂When you add
Slightly large degree of lateral etching just below the disk
It is difficult to shorten the overall processing time
It becomes possible.

Further, Ar in CO ₂ plasma gas, He,
Rare gas such as Ne or Xe or N which does not etch the mask
₂ , NO, N ₂ O, etc. may be added as a diluting gas. By adding a dilution gas, the plasma can be stabilized.

When a high frequency bias is applied to the substrate when etching the organic film, the anisotropy is further improved.

In the present invention described above, a photoresist containing Si may be formed directly on the organic film, and the organic film may be etched using the photoresist as a mask.

In the method of manufacturing a magnetic head according to the present invention, an organic film is formed on a substrate; an etching mask is formed on the organic film; and the organic film is etched using plasma using CO ₂ . Thereafter, a pole material is formed using the etched organic film as a mold.

In the magnetic head according to the present invention, a step of forming an organic film on a substrate; a step of forming an etching mask on the organic film; and a step of etching the organic film using plasma using CO _2. A step of forming a pole material using the etched organic film as a mold.

In the manufacturing process of the magnetic head of the present invention, when a mold for forming a magnetic pole is manufactured, CO is used as a plasma gas.
_Since the organic film is etched using No. ₂ , fine processing accuracy is improved. In particular, the above-described etching process is effective for the magnetic pole of a magnetic head having a relatively large thickness.

[0020]

1A to 1C show an etching process according to a first embodiment of the present invention. This embodiment is applied to the manufacture of a plating die used for molding the tip of a magnetic head for a hard disk.

First, a lower structure (not shown) of a magnetic head and a permalloy 40 serving as a seed for plating are formed on an AlTiC substrate. A resist 42 is applied thereon with a thickness of 5 μm, and a silicon oxide film 44 is formed thereon with a thickness of 500 nm. Further, a photoresist 46 is applied thereon with a thickness of 1 μm, and a groove pattern 4 having a width of 0.5 μm is formed.
8 is formed by photolithography. The state is shown in FIG. As the resist 42, a general organic material can be used. For example, besides resins such as polyimide, g-line resist (OFPR80) manufactured by Tokyo Ohka Kogyo Co., Ltd.
0), i-line resist (THMR-iN200), g-line resist (PFRGX) manufactured by Nippon Synthetic Rubber Co., Ltd., or the like can be used.

Next, as shown in FIG. 1B, using the photoresist 46 as a mask, the underlying silicon oxide film 44 is etched using a general silicon oxide film etching apparatus (not shown).

Thereafter, an ECR etching apparatus described later is used.
Using the silicon oxide film 44 as a mask
The layer resist 42 is plasma-etched under the following conditions.
You. Microwave (2.45 GHz): 1.5 kW RF bias (400 kHz): 200 W Plasma gas: CO₂  Gas flow rate: 100 sccm Gas pressure: 5 mTorr Sample stage temperature: -20 ° C

What is important in the present invention is that in the above-described plasma etching process, CO ₂ is used as a plasma gas and no halogen-based gas is contained.

In the plasma processing step, the uppermost photoresist 46 is etched away, but the plasma does not contain a halogen element such as fluorine for etching the silicon oxide film 44 serving as a mask. Oxide film 44 is hardly etched. As a result, etching of the underlying resist 42 proceeds using the silicon oxide film 44 as a mask. This state is shown in FIG.

Next, the configuration of the above-described ECR plasma etching apparatus will be briefly described. In general, an ECR plasma processing apparatus is promising as an apparatus that can generate plasma with high activity under a low gas pressure region by utilizing electron cyclotron resonance (ECR) for exciting plasma, and is being put to practical use. In.

FIG. 2 shows the EC used in the embodiment of the present invention.
1 shows a configuration of an R plasma etching apparatus. The plasma etching apparatus performs an etching process on an organic film (42) of a material to be processed 10, and includes a hollow cylindrical plasma generation chamber 12 for generating plasma, and a reaction chamber connected to the plasma generation chamber 12. A room 14 is provided. The material to be processed 10 is in the state shown in FIG. 1B, and is brought into the state in FIG. 1C by the present apparatus.

A circular waveguide 16 connected to a microwave oscillator (not shown) such as a magnetron is connected to the upper part of the plasma generation chamber 12, and the microwave is applied to the plasma via the circular waveguide 16. It is designed to lead to the generation chamber 12.

A microwave introducing window 20 is arranged between the circular waveguide 16 and the plasma generation chamber 12. The microwave introduction window 20 is made of a microwave transmitting material such as quartz glass, and is designed to hermetically seal the plasma generation chamber 12. Outside the plasma generation chamber 12, three-stage main coils 18, 20, and 22 including a connection portion of the circular waveguide 16 and surrounding them concentrically are arranged. Below the main coils 18, 20 and 22, a one-stage sub coil 24 is arranged. The main coils 18, 20, 22 and the sub coil 24 are connected to the current supply unit 3
2 is supplied with necessary current from the plasma generation chamber 12.
A region satisfying the ECR condition is formed in the region.

The plasma generation chamber 1 is provided on the side wall of the reaction chamber 14.
An exhaust pipe 28 for exhausting the gas from the second and reaction chambers 14 is provided, and the plasma generation chamber 12 and the reaction chamber 14 are maintained in a high vacuum state by evacuation from the exhaust pipe 28. The reaction chamber 14 is provided with a gas supply pipe 30 for supplying a plasma gas required for plasma generation. Although not shown, a cooling water channel is formed around the plasma generation chamber 12, and the cooling water circulating through the cooling water channel cools the plasma generation chamber 12.

In the reaction chamber 14, there is provided a sample table 26 for holding the material to be processed 10 by fixing means such as electrostatic attraction. A high-frequency power source 34, one end of which is grounded, is connected to the sample stage 26, and an RF bias voltage is applied to the sample stage 26. Thereby, the chemical reaction occurring near the surface of the material to be processed 10 can be promoted, and the etching rate can be improved.

Next, the overall operation of the plasma processing apparatus will be briefly described. First, the material to be processed 10 is fixed on the sample stage 26, and is evacuated from the exhaust pipe 28 to
The internal pressure of the plasma generation chamber 12 and the reaction chamber 14 is reduced to a predetermined pressure. Next, a plasma gas (CO2) is introduced from the gas supply pipe 30 into the plasma generation chamber 12 and the reaction chamber 14, and the internal pressure of the plasma generation chamber 12 and the reaction chamber 14 is reduced to 5 × 1.
Keep around 0-3 Torr.

Thereafter, a magnetic field is formed in the plasma generation chamber 12 by energizing the main coils 18, 20, 22 and the sub-coil 24, and a micro-wave is introduced into the plasma generation chamber 12 from the circular waveguide 16 through the microwave introduction window 20. Introduce the waves. This microwave has a frequency f = 2.45 GH
z (wavelength λ = about 12.2 cm) and power of about 1500 W.

When microwaves are introduced into the plasma generation chamber 12, the plasma gas is resonantly excited on the ECR surface 100 to generate plasma. The plasma generated in the plasma generation chamber 12 is drawn out to the reaction chamber 14 by the action of the divergent magnetic field formed by the main coils 18, 20, 22 and the sub-coil 24, and the material 1 on the sample stage 26 is processed.
Irradiation is performed on the surface 0 to perform etching.

As described above, in this embodiment, by using CO ₂ as the plasma gas, the fine processing performance (5 μm) which cannot be obtained with other gases (O ₂ , CO) is obtained.
(thickness of 0.5 m or less in m thickness), an excellent etching rate and anisotropy are obtained. As a mask for etching the resist 42, in addition to the silicon oxide film,
iN, polycrystalline silicon, Si-containing resist and the like can be used. Since these mask materials are etched by fluorine, chlorine and the like, a gas (fluorine, chlorine, SF ₆ or C ₆ ) containing these elements (fluorine, chlorine or the like) is used.
Fluorocarbon gas F _4, etc., etc.) it is important not to use. Further, when a metal film exists under the resist (42), corrosion occurs due to chlorine, so that chlorine gas cannot be used from this point.

Since an RF bias is applied to the substrate 10, ions containing oxygen are accelerated toward the substrate 10, and substantially vertical etching is performed using the silicon oxide film 44 as a mask. In addition, since oxygen gas is not used, oxygen molecular radicals that cause isotropic etching are small, and etching in the lateral direction immediately below the mask is suppressed.

In this embodiment, the etching rate of the groove portion 48 is 700 nm / min, and a substantially vertical etching shape can be obtained. The difference between the width of the groove 48 formed by lithography at the stage of FIG. 1A and the width of the groove 48 after the etching at the stage of FIG. 1C is 0.05 μm or less.

In the above embodiment, only CO ₂ is used as the plasma gas for the plasma etching.
CO can be added to this. By adding CO, etching can be performed with higher precision, although the etching rate is slightly lowered. That is,
The difference between the width of the groove formed by lithography and the width of the etched groove can be further reduced.

Further, when O ₂ is added to CO ₂ , the degree of progress of the etching in the lateral direction immediately below the silicon oxide film 44 is slightly increased, but the overall processing time can be reduced.

Further, in order to stabilize the plasma, a rare gas such as Ar, He, Ne, Xe or the like,
A gas such as N ₂ , NO, or N ₂ O which does not etch the mask may be added as a diluting gas.

Silicon as an etching mask for the organic film
Si-containing resist instead of oxide film and photoresist
Can also be used. In this case, the Si-containing resist
After forming the pattern by photolithography, for example
O₂, CO₂Irradiation with plasma containing oxygen or the like. this
Removes carbon in the Si-containing resist to remove SiO ₂
To a layer whose main component is
Etch the layer resist.

More specifically, a polyimide film having a thickness of 10 μm is formed on a silicon substrate, and a Si-containing photoresist is applied thereon by 1 μm. A desired pattern is formed on the photoresist by photolithography. Thereafter, etching is performed under the resist etching conditions of the first embodiment.

At this time, the Si-containing photoresist is first exposed to plasma, and carbon in the photoresist is removed by oxygen-containing ions in the plasma. This leaves SiO ₂ in the photoresist layer. Since this SiO ₂ is not further etched by ions containing oxygen, this layer serves as a mask, and the underlying polyimide can be etched into a predetermined pattern.
In this case, by using the Si-containing photoresist, the etching of the mask and the etching of the underlying polyimide can be performed in one step, which is effective in shortening the steps.

The above-mentioned photoresist may be converted into SiO ₂ under a condition other than the etching of the underlying resist, such as plasma using only O ₂ . In this embodiment, as in the first embodiment, CO, CO ₂ , and a diluent gas may be added in consideration of dimensional accuracy, processing time, and stability.

FIG. 5 shows an etching shape when an organic film is plasma-etched using O ₂ / CO gas as a plasma gas (conventional example). As can be seen from the drawing, the etching in the lateral direction proceeds immediately below the silicon oxide film mask 142, and a substantially vertical etching shape cannot be obtained. Reference numeral 140 denotes a permalloy, and 144 denotes a silicon oxide film.

FIG. 3 schematically shows a hard disk head manufactured by partially adopting the above-described etching method. In the figure, reference numeral 52 indicates a hard disk, and 54 and 56 indicate Permalloy magnetic poles. Reference numeral 58 indicates a coil. The embodiment described below is applied to the manufacture of the tip portion 60 of the permalloy magnetic pole 54.

FIGS. 4A to 4D show a process of manufacturing a magnetic head according to the present invention. Note that components corresponding to the embodiment shown in FIG. 1 are denoted by the same reference numerals, and redundant description will be omitted. The substrate illustrated in FIG. 4A is in the same state as in FIG. As shown in FIG. 4B, a permalloy 62 is formed in the groove 48 by plating or the like.

Next, the resist 42 is removed by a general ashing device (FIG. 4C). Further, as shown in FIG. 4D, the entire permalloy 62 is uniformly etched by a method such as ion milling, so that only the resist type permalloy portion 62 remains, and the magnetic pole (5
4) is formed.

Although the embodiments of the present invention have been described above, the present invention is not limited to a plating type for forming a permalloy magnetic pole of a magnetic head for a hard disk, but may be an organic anti-reflection film (ARC) used for manufacturing LSIs. The present invention can be applied to the etching of organic materials such as an interlayer insulating film, a head portion (mainly made of polyimide) for ejecting ink of an ink jet printer, a type of copper wiring of an LSI, and fine processing (width of about 1 μm or less).

[0050]

As described above, in the etching method according to the present invention, since CO ₂ is used as a plasma gas and plasma etching is performed without using a halogen-based gas, damage to a mask is minimized. And the precision of the fine processing of the organic film can be dramatically improved. As a result, in the magnetic head manufacturing method according to the present invention, fine processing (width 0.5 μm or less) at the tip of the magnetic head can be performed satisfactorily.

[Brief description of the drawings]

FIGS. 1A and 1B are sectional views showing steps of an organic film etching method according to a first embodiment of the present invention, wherein FIG. 1A shows a state after a photolithography process, and FIG. The state after etching is shown, and (C) shows the state after resist etching.

FIG. 2 is an explanatory diagram showing a configuration of an ECR plasma etching apparatus used in an embodiment of the present invention.

FIG. 3 is an explanatory view showing a schematic configuration of a magnetic head for a hard disk to which another embodiment of the present invention is applied;

FIG. 4 is a cross-sectional view (perspective view) showing steps of a method of manufacturing a magnetic head according to another embodiment of the present invention;
1 (C) shows a state corresponding to FIG. 1 (C), (B) shows a state after permalloy plating, (C) shows a state after removal of the resist, and (D) shows only a resist type permalloy portion. It shows the state that it was turned on.

FIG. 5 is a cross-sectional view showing a state (prior art) in which a resist is etched using an O ₂ / CO gas.

[Explanation of symbols]

 Reference Signs List 40 permalloy 42 resist (organic film) 44 silicon oxide film (mask) 46 photoresist 48 groove 52 hard disk 54 permalloy magnetic pole 62 permalloy portion

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Junichiro Asayama 1-8 Fuso-cho, Amagasaki-shi, Hyogo F-term in the Semiconductor Equipment Division of Sumitomo Metal Industries, Ltd. (Reference) 2H096 AA27 HA24 HA25 JA04 5D033 BA13 DA04 DA08 5F004 BA14 BA16 BB11 BB14 BB18 BB22 CA06 DA00 DA22 DA23 DA25 DA26 DB00 DB03 DB23 DB25 DB26 EA03 EA06 EA07 5F046 LB01 LB09 NA01 NA07 NA18

Claims (13)

[Claims] 1. A method for etching an organic film formed on a substrate by using plasma, wherein CO ₂ is used as a plasma gas and the plasma gas does not contain a halogen-based gas. Etching method. 2. The plasma gas contains at least CO, O,
_2. The organic film etching method according to claim 1, wherein one of the _two is mixed. 3. The organic film etching method according to claim 1, wherein a predetermined diluent gas is mixed with the plasma gas. 4. The organic film etching method according to claim 1, wherein a high frequency bias is applied to the substrate when etching the organic film. 5. The method according to claim 1, wherein a photoresist containing Si is formed immediately above the organic film, and the organic film is etched using the photoresist as a mask.
5. The method for etching an organic film according to 2, 3, or 4. 6. A method for manufacturing a magnetic head, comprising: forming an organic film on a substrate; forming an etching mask on the organic film; and forming the organic film using a plasma using CO _2. A method of manufacturing a magnetic head, comprising: a step of etching; and a step of forming a magnetic pole material using the etched organic film as a mold. 7. The CO used in the etching step.₂Step
At least CO, O ₂One of
7. The magnetic head according to claim 6, wherein:
Construction method. 8. The method according to claim 6, wherein a predetermined diluent gas is mixed with the CO ₂ plasma gas used in the etching step. 9. The method according to claim 6, wherein a high frequency bias is applied to the substrate in the etching step.
9. The method for manufacturing a magnetic head according to 7 or 8. 10. A process for forming an organic film on a substrate; forming an etching mask on said organic film; CO ₂
A magnetic head manufactured by a method comprising: a step of etching the organic film using plasma using a method; and a step of forming a pole material using the etched organic film as a mold. 11. The CO used in the etching step.₂
The plasma gas contains at least CO, O ₂One of
The magnetic head according to claim 10, wherein the magnetic head is mixed.
De. 12. The CO ₂ used in the etching step.
12. The magnetic head according to claim 10, wherein a predetermined dilution gas is mixed with the plasma gas. 13. The method according to claim 1, wherein a high frequency bias is applied to the substrate in the etching step.
13. The magnetic head according to 0, 11 or 12.