JPH07331429A - Formation of thin film - Google Patents

Abstract

PURPOSE:To stably form a good-quality protective thin film excellent in step coverage and reduced in stress at the time of forming the protective film on a thin-film magnetic head by alternately conducting the formation of the thin film by sputtering and etching. CONSTITUTION:An oxide film of Al2O3, etc., is formed by sputtering as the protective film of the transducer part of a thin-film magnetic head. In this case, the Al2O3, film is firstly formed by the low-bias sputtering of <100V bias voltage, and then the film 32 projectingly grown from the corner of the step 31 on the surface is etched by high bias plasma. The sputtering and etching are alternately repeated plural times to concentratedly etch the Al2O3 film 33 projectingly grown from the corner of the step 31, and a good-quality Al2O3 thin film 34 excellent in step coverage and reduced in stress is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film forming method capable of obtaining a good quality thin film having good step coverage and less film stress.

[0002]

2. Description of the Related Art As a magnetic head such as background recent hard disk drive device of the invention, can be thin-film head in size and recording density has been used. This thin film type head includes an electromagnetic induction type (hereinafter referred to as an Ind head) and a magnetoresistive effect element (hereinafter referred to as an MR element) whose resistance is changed by a magnetic field.
There is a magnetoresistive effect type (hereinafter, referred to as MR head) utilizing the. The Ind head is composed of a core (magnetic core) and a coil in which a gap for locally performing electromagnetic conversion is formed, and performs recording or reproduction on a magnetic recording medium (magnetic disk) by electromagnetic induction. The head is composed of an MR element having electrodes formed at the front and rear ends thereof facing the magnetic recording medium, and a conductor (hereinafter referred to as a bias conductor) for applying a bias magnetic field to the MR element for linearizing the characteristics. Which reproduces a change in magnetic field as a change in resistance, and a composite head (hereinafter,
MR / Ind head).

3 and 4 are plan views or cross-sectional views showing an example of a transducer portion (a portion for performing electromagnetic conversion) of an MR / Ind head. In FIG. 4, a first thin film magnetic core 2, a first insulating layer 3, a second thin film magnetic core 4, a second insulating layer 5, a third thin film magnetic core 6 and a protective film are provided on a substrate 1. 7 are sequentially stacked to form a film-shaped MR element 8, electrodes 9 and 10 and a bias conductor 11 in the first insulating layer 3, and a coil pattern 12 is formed in the second insulating layer 5. There is. This MR / Ind head
A recording gap 14 as an Ind head is formed on the upper side of the one end face 13 side, and a reproducing gap 15 (two layers above and below the MR element 8) as an MR head is formed below the one end face 13 to magnetically record the one end face 13. The recording medium performs electromagnetic conversion by facing the medium with a minute gap and running, and functions as a recording and reproducing head.

By the way, the protective film 7 in the MR / Ind head is usually made of an oxide film of Al ₂ O ₃ or the like and protects the entire transducer portion, and is important in preventing deterioration of the head. Since the step (that is, the step portion) 16 including the thin film magnetic core 6 and the terminal portion 12a (shown in FIG. 3) of the coil pattern 12 is 30 to 40 μm, it is formed as a good quality film that covers this without gaps. It was difficult and problematic in the past.

A conventional thin film forming method, that is, a thin film of this type is conventionally formed by so-called sputtering. At this time, in order to improve the coverage of the step portion 16, a bias sputtering method (during film formation) is used. Not only on the target side but also on the substrate side at the same time-
This is a sputtering method in which the film on the substrate is etched to some extent by applying a voltage of about 50 to 250V. ) Was adopted, and the treatment was performed with a high bias of −150 V or higher.

That is, as shown in FIG.
When a film is formed by low-bias or non-bias sputtering on a portion having a step 21 of ˜40 μm,
Film formation proceeds as shown in FIGS. 5B and 5C, but the film 2 at the corner of the step 21 is formed in the middle of film formation as shown in FIG. 5C.
As a result of the growth of No. 2, a region where the film is not grown is generated.
A cavity (crack) 23 is formed after the film formation shown in (d), which causes deterioration of the core of the transducer part, the terminals of the coil pattern, and the like. However, -15
When a high bias of 0 V or higher is applied, the voltage shown in FIG.
As shown in (c), the step 2 is formed in the early and middle stages of film formation.
Since the film 22 at the corners of No. 1 is projected, it is intensively etched, so that no region where the film is not grown does not occur, and the coverage is good after the film formation shown in FIG. 5D. This is because a film can be obtained.

[0007]

By the way, in the conventional thin film forming method, since the film is formed by the bias sputtering method with a high bias voltage of -150 V or more, although the coverage of the step portion is good, FIG. As shown, the film stress (internal stress of the film) was high, and there were the following problems. (A) Film peeling occurs where adhesion of the head portion is weak, resulting in poor yield. (B) Since the substrate is warped, the end point varies within the wafer during polishing of the protective film in the next step. (C) The magnetic characteristics of the head are changed to significantly reduce the yield.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a thin film forming method capable of obtaining a good quality thin film having good step coverage and less film stress.

[0009]

In order to achieve the above object, a thin film forming method according to the invention of claim 1 is a sputtering step of depositing a film material on a surface of a substrate by a predetermined thickness, and a deposition step in the sputtering step. The film is formed on the surface of the substrate by alternately performing an etching step under the condition of etching the resulting film by a film thickness smaller than the predetermined thickness.

The thin film forming method according to the second aspect of the invention is characterized in that the film material is an oxide such as Al ₂ O ₃ .

A thin film forming method according to a third aspect of the invention is characterized in that the thin film is a protective film for a thin film magnetic head.

The thin film forming method according to a fourth aspect of the invention is characterized in that the sputtering method in the sputtering step is a bias sputtering method with a bias voltage of less than -100V.

[0013]

In the present invention, the deposition of the film material by the sputtering process and the etching process under the condition of etching a part of the film thickness of the deposition are alternately performed to form the film. Even if there is a level difference of about 30 to 40 μm on the surface, the film grown at the corners of the level difference in the sputtering process is intensively etched in the etching process, and even if the bias sputtering method is not particularly adopted,
It is possible to suppress the protruding growth of the film at the corners of the step and form a film having good coverage without cracks. Therefore, a film having a small film stress and good coverage can be obtained.

Even when the bias sputtering method is adopted as the sputtering method, the bias voltage is -100.
Since it is less than V, a film having particularly small film stress and good coverage can be obtained, and another effect by the bias sputtering method, that is, an effect of preventing sputter gas from mixing into the film is also exhibited.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In this embodiment, the MR shown in FIGS.
This is an example of forming a thin film such as the protective film 7 of the / Ind head. However, since the configuration and manufacturing method of the MR / Ind head are the same as those of the conventional example described above, the description thereof will be given using the same reference numerals for corresponding elements. Omit it.

The protective film forming method of this embodiment comprises a sputtering step of depositing a film material (oxide such as Al ₂ O ₃ ) by a predetermined thickness on the substrate surface by sputtering, and a deposition step in the sputtering step. The film is formed on the surface of the substrate by alternately performing an etching process in which the film is etched by a thickness smaller than the predetermined thickness. Specifically, the sputtering process is performed by a bias sputtering method of low bias (less than -100V). After this sputtering process is performed for about 1 hour 30 minutes to 2 hours, an etching step of about 30 minutes to 1 hour is performed by plasma etching. The processing performed by the method is repeated about 7 to 8 times.

When the film is formed by the above method, as shown in FIG.
Even on a surface having a step 31 of about m, film formation proceeds in the sputtering process as shown in FIG.
Then, in the etching step, the film 32 that has grown to protrude to the corner of the step 31 in this sputtering step is
As shown in FIG. 1C, the etching is intensively performed, and the other portions are slightly etched. Then, in the next sputtering step, film formation progresses as shown in FIG. 2D, and in the next etching step, the film 33 that protrudes and grows at the corner of the step 31 in the sputtering step is also formed in FIG. The phenomenon of intensive etching as shown in e) is repeated.

Therefore, while the protruding growth of the film at the corners of the step 31 is suppressed and the condition of the sputtering process is thicker than that of the etching process, the film formation progresses as a whole, and the final film formation is completed. A region where the film does not grow is not generated, and a thin film 34 (corresponding to the protective film 7 in this embodiment) having good coverage is obtained after the film formation shown in FIG. 2F. Moreover, since the bias sputtering method is of low bias, the thin film 34 has a remarkably small film stress as shown in FIG. 7 as compared with the case of high bias (-150 V or more). Further, since the bias sputtering method is adopted, it is possible to prevent the sputtering gas from being mixed into the film, and to obtain a thin film of good quality in terms of purity.

As described above, according to the protective film forming method of this embodiment, it is possible to surely obtain a high-quality film having good step coverage, small film stress and high purity. Therefore, the peeling and cracking of the protective film 7 are surely prevented, the warp of the substrate is surely avoided, there is no variation in the end point at the time of polishing the protective film, and it is hard to deteriorate and the magnetic characteristics are stable. It will be possible to produce high quality thin film magnetic heads with extremely high yield. The present invention is not limited to the case of forming the protective film (oxide film) of the thin film magnetic head, but is widely applied to the case of forming a thin film having a small film stress on a stepped surface with good step coverage. It goes without saying that the same effect is achieved.

[0020]

According to the present invention, it is possible to surely obtain a high-quality film having good step coverage, small film stress, and high purity. Therefore, when applied to the protective film formation of a thin film magnetic head, the occurrence of peeling and cracks of the protective film is surely prevented, the warp of the substrate is surely avoided, and the end point variation during polishing of the protective film is prevented. Not with
It is possible to produce a high-quality thin film magnetic head that is hard to deteriorate and has stable magnetic characteristics with good yield.

[Brief description of drawings]

1A and 1B are side cross-sectional views showing a film forming situation according to an embodiment of a thin film forming method of the present invention, wherein FIG. 1A is a view showing a situation before film formation, and FIG. 1B is immediately after a first sputtering process. FIG. 3C is a diagram showing a situation immediately after the first etching step.

2A and 2B are side cross-sectional views showing a film formation state according to an embodiment of a thin film forming method of the present invention, FIG. 2D shows a state immediately after a second sputtering step, and FIG. FIG. 6 is a diagram showing a situation immediately after the etching process, and FIG.

FIG. 3 is a plan view showing an example of a transducer unit of the MR / Ind head.

FIG. 4 is a cross-sectional view showing an example of a transducer part of an MR / Ind head.

5A and 5B are side cross-sectional views showing a film formation state by non-bias or low-bias sputtering, FIG. 5A showing a state before film formation, and FIG. 5B showing a state at an initial stage of film formation;
(C) is a diagram showing a situation in the middle stage of film formation, and (d) is a diagram showing a situation at the end of film formation.

6A and 6B are side cross-sectional views showing a film formation state by high bias sputtering, wherein FIG. 6A is a diagram showing a state before film formation, FIG. 6B is a diagram showing a state at the initial stage of film formation, and FIG. FIG. 4A is a diagram showing a situation in the middle of film formation, and FIG. 7D is a diagram showing a situation at the end of film formation.

FIG. 7 is a diagram showing a relationship between a film stress of a thin film formed by a bias sputtering method and a bias voltage.

[Explanation of symbols]

 7 Protective film (thin film) 16 Step part (step) 31 Step

Claims (4)

[Claims] 1. A sputtering step of depositing a film material on a surface of a substrate by a predetermined thickness, and an etching step under the condition of etching the film deposited in the sputtering step by a film thickness smaller than the predetermined thickness. Is alternately performed to form a film on the surface of the substrate. 2. The thin film forming method according to claim 1, wherein the film material is an oxide such as Al ₂ O ₃ . 3. The thin film forming method according to claim 1, wherein the thin film is a protective film for a thin film magnetic head. 4. The sputtering method in the sputtering step is a bias sputtering method in which a bias voltage is less than −100V.
The thin film forming method described.