JPH04329613A - Manufacture of magnetic pattern - Google Patents

Abstract

PURPOSE:To provide a method for manufacturing magnetic patterns, by which the resolution of the magnetic pattern is improved and further, the S/N of the output signal of sensing a position can be increased. CONSTITUTION:The method for manufacturing magnetic patterns comprises a first process for forming a protective film 18 on the exposed surface of a substrate 20 after covering selectively the surface of the substrate with metallic films 12 by a photoetching process, a second process for forming predetermined patterns on the substrate 20 by removing the metallic films 12 and by etching the exposed parts of the substrate 20, a third process for embedding magnetic materials in etched grooves 22 of the patterns formed by the second process, and a fourth process for magnetizing the magnetic materials.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing magnetic patterns.

0002

2. Description of the Related Art Generally, a magnetic recording/reproducing apparatus uses a magnetic head made of an electromagnet or the like and a magnetic body made of a micromagnet or the like. In the case of magnetic recording, a magnetic head generates a magnetic field that changes in accordance with recorded information, causes a positional change in residual magnetism in a magnetic body moving in the magnetic field, and records information on the magnetic body. On the other hand, in the case of magnetic reproduction, a magnetic head detects a positional change in the residual magnetism of a magnetic body as a voltage change, and reproduces recorded information from the magnetic body.

The above-mentioned principle of magnetic recording and reproducing is also used in magnetic sensors. That is, a predetermined magnetic pattern is manufactured with high positional accuracy by a recording magnetic head, and the magnetic pattern is detected by a detection magnetic head to obtain positional information. Here, as an example of a conventional method for manufacturing a magnetic medium, an example of manufacturing a linear magnetic pattern will be described.

First, a magnetic pattern manufacturing apparatus 1 shown in FIG. 8 is prepared. The magnetic pattern manufacturing device 1 includes a position detector 2, interlocking members 3 and 4, an actuator 5, and a magnetic head 6.
and an I/V circuit (current-voltage conversion circuit) 7. The magnetic recording medium 8 is connected to the position detector 2 and the actuator 5 by interlocking members 3 and 4. The actuator 5 moves the magnetic recording medium 8 in the directions of arrows A and B in FIG.
Detect the position of.

Next, the magnetic recording medium 8 is moved and fixed at a predetermined position by the actuator 5, and the tip of the magnetic head 6 is brought into contact with the magnetic recording medium 8. Next, a current is applied from the I/V circuit 7 to the coil of the magnetic head 6 to generate a magnetic field, and the magnetic recording medium 8 near the gap at the tip of the magnetic head 6 is magnetized. Next, the actuator 5 moves the magnetic recording medium 8 to another position. Specifically, the position of the moving magnetic recording medium 8 is detected by the position detector 2, and the actuator 5 moves and fixes the magnetic recording medium 8 to a desired position based on the detection result of the position detector 2. Next, the magnetic recording medium 8 is magnetized by the magnetic head 6 in the same manner as described above. Thereafter, all predetermined portions of the magnetic recording medium 8 are similarly magnetized to produce a magnetic recording medium 8 having a predetermined magnetic pattern.

[0006]

[Problems to be Solved by the Invention] However, in such a conventional magnetic medium and its manufacturing method, when the magnetic medium is, for example, a magnetic scale, there is a problem in magnetic detection due to the following reasons. There are problems in that the S/N ratio of the detection signal becomes small and it becomes difficult to improve the resolution of magnetic detection.

That is, since the leakage magnetic flux of the magnetic head 6 is used when magnetizing the magnetic recording medium 8, a strong magnetic field cannot be applied to the magnetic recording medium 8, and the position is detected by using it as a scale. The S/N ratio of the signal becomes small. Also, the resolution of the magnetic scale is higher than that of the magnetic head 6.
Since it is determined by the magnetization accuracy of , improving resolution requires a large capital investment in manufacturing equipment, making it difficult to improve resolution.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method of manufacturing a magnetic pattern that can improve the resolution of the magnetic pattern and further increase the S/N ratio of the output signal for position detection.

[0009]

[Means for Solving the Problems] In order to solve the above problems, the present invention selectively covers the surface of a substrate material with a metal film using a photo-etching process, and then coats the exposed surface of the substrate material with a protective coating. a first step of forming a predetermined pattern on the substrate material by removing the metal film and etching the exposed portion of the substrate material; This method is characterized by comprising a third step of embedding a magnetic material in the etched grooves of the pattern, and a fourth step of magnetizing the magnetic material.

0010

[Operation] In the present invention, by forming a metal film by a photo-etching process in the first step, the metal film is formed in the second step.
In the process, a predetermined pattern is formed by etching with high positional accuracy, and resolution can be improved simply by replacing the photolithography mask pattern.

Furthermore, by magnetizing the magnetic material after embedding it in the etched groove, it becomes possible to apply strong magnetization to the magnetic material, and as a result, a strong magnetic field strength is obtained during position detection. The S/N ratio of the output signal of is increased. Furthermore, it is now possible to process the etching used in the first and second steps using only so-called wet etching, eliminating the need for dry etching equipment such as generally expensive RIE (reactive ion etching) equipment. Become.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below based on the drawings. 1 to 7 are process diagrams showing an embodiment of the method for manufacturing a magnetic pattern according to the present invention, and are an example in which a silicon substrate is used as the substrate. First, a silicon (hereinafter referred to as Si) substrate or a (11
0) Prepare the substrate 11 whose surface is exposed, and remove dust, dirt, etc. from the Si substrate 11 using a cleaning method similar to that used in semiconductor processes.

Next, a metal film 12 is formed on the surface of the clean Si substrate 11 using a vacuum film forming apparatus such as an evaporation apparatus or a sputtering apparatus, as shown in FIG. 1(b). metal film 1
The film thickness of No. 2 is about 1 μm. This film thickness is sufficient to prevent the underlying Si from being oxidized through the masked metal layer in the process of forming an Si oxide film, which will be described later.
Moreover, it is sufficient to select an economical thickness. Below, metal film 1
2 is made of Cr.
1 and metal film 12 is referred to as a Cr/Si substrate 13.

Next, as shown in FIG. 1(c), Cr/
A resist 14 made of a resist agent to be described later is spin-coated on the surface of the Si substrate 13 on the metal film side. Specifically, several drops of a photoresist agent made of an organic resin are placed on the center of the substrate surface of the Cr/Si substrate 13, and the Cr/Si substrate 13 is rotated around an axis that passes through this center and is perpendicular to the substrate surface. A resist agent is spread thinly and uniformly on the substrate surface, and placed in a constant temperature bath heated to about 100° C. to stabilize the resist agent. This resist agent is used as a mask for the Cr etching process described later, so it only needs to be resistant to the Cr etching solution, which is a mixture of red blood salt and caustic soda water. For example, AZ-1350 (positive type) or OMR -83 (negative type) can be used.

Next, as shown in FIG. 2(d), the glass plate 15 on which a predetermined pattern has been written is placed on the Cr/Si substrate 1.
Place the glass plate 1 on the resist 14 of No. 3.
UV rays are irradiated through 5. The glass plate 15 is selectively coated with a material 15a that does not transmit ultraviolet rays, and when the glass plate 15 is irradiated with ultraviolet rays from the side, the portions of the resist 14 coated with the material 15a that does not transmit ultraviolet rays are exposed to ultraviolet rays. The remaining portion of the resist 14 is irradiated with ultraviolet rays. Resist 14 only in the area irradiated with ultraviolet rays
causes a selective photochemical reaction. Generally, there are two types of photoresists: negative-type photoresists that cause a photo-insolubilization reaction when exposed to ultraviolet light, and positive-type photoresists that cause a photo-solubilization reaction. explain.

Next, the Cr/Si substrate 13 is coated with a resist 1.
As shown in FIG. 2(e), only the masked portion of the resist 14, that is, the portion that did not undergo the photoinsolubilization reaction, is dissolved and removed from the Cr/Si substrate 13, and the Cr/Si substrate 13 is immersed in a developer. /The surface of the metal film 12 of the Si substrate 13 is selectively exposed. Cr generated by this development process
The pattern formed by the exposed surface of the metal film 12 of the /Si substrate 13 is the same as the predetermined pattern of the glass plate 15 described above, and is a transfer of the predetermined pattern of the glass plate 15.

Next, as shown in FIG. 2(f), Cr, that is, the metal film 12, is etched using the Cr etchant 16 described above. Specifically, the above-mentioned etching solution (a mixture of red blood salt and caustic soda water) is placed in a large flat-bottomed beaker 17, the large-sized flat-bottomed beaker 17 is placed on a stirring device (not shown), and a stirrer (not shown) is placed in the beaker. The rotation speed of the stirrer was set to 600 rpm, and the Cr/Si substrate 13 was placed. When the exposed portion of the metal film 12 has been etched, the Cr/Si substrate 13 is taken out from the etching solution 16 and immersed in pure water to remove the etching solution. As a result, the predetermined pattern is transferred to the pattern of the metal film 12, and the surface of the Si substrate 11 is selectively exposed.

Next, as shown in FIG. 2(g), the resist 14 is removed. Next, the Cr/Si substrate 13 is
Oxidation is performed in a horizontal annular furnace (not shown) heated to 00.degree. C. to form a SiO2 film 18 on the exposed surface portion of the Si substrate 11, as shown in FIG. 3(h). Hereinafter, the unoxidized portion of the Si substrate will be referred to as Si part 19.
The substrate made of the SiO2 film 18 is referred to as a SiO2/Si substrate 20. Specifically, when oxidizing the substrate, approximately 80
Oxygen passed through water heated to ℃ is fed into the furnace. It is known that oxygen after passing through heated water contains sufficient moisture (H2O), and that oxygen containing moisture accelerates the oxidation rate of Si. Actually, the oxygen in the water vapor oxidizes the Si substrate 11. For example, in an oxidation reaction tube with an inner diameter of 50 mm and a length of 1000 mm, a Si substrate 1 of 10 x 10 mm and a thickness of 0.3 mm is prepared.
The oxygen flow rate when oxidizing the sheet is about 0.2 liters/minute. Oxygen containing steam at 1000° C. is flowed into the annular furnace to oxidize the Si surface for 5 hours. In this oxidation step, almost no SiO2 film is formed on the Si portion covered by the metal film 12.

Next, the SiO2/Si substrate 20 is immersed in the aforementioned Cr etching solution or a suitable acid or alkaline solution to remove the remaining metal film 12, as shown in FIG. 3(i). At this point, Si is exposed in the portion where the metal film 12 remained, and SiO2 is exposed in the other portions. Next, as shown in FIG. 3(j), the SiO2/Si substrate 20 is immersed in a potassium hydroxide (KOH) aqueous solution 21 to react, and the exposed portion of the Si portion 19 is etched in a direction perpendicular to the substrate surface to form a groove. 22 is formed. The exposed surface of the Si portion 18 of the SiO2/Si substrate 20 is
) plane, the sidewalls of the grooves 22 formed by the above-described etching are substantially perpendicular to the substrate surface. For more information,
In the case of single-crystal silicon, the etching rate ratio is determined by its crystal direction, and the ratio of the etching rate of the (110) plane to the etching rate of the (111) plane is about several 500 times. When the thickness of the Si substrate is 500 μm, (111
) direction is 1.0 μm. Further, the etching rate in the (110) direction is about 1 to 5 μm/min. Therefore, 100 to 500 minutes (1 hour 40 minutes to 8 hours 20 minutes) is required to perform etching of 500 μm. In this example, first, potassium hydroxide is weighed and put into a beaker, and pure water is weighed and mixed with a measuring cylinder so that the concentration is 44% by weight. Potassium hydroxide has good hydrophilic properties and can easily be prepared into an aqueous solution with a concentration of 44% by weight. At this time, an exothermic reaction occurs, so it is necessary to pour the pure water into the beaker in several portions. After adding pure water, the beaker is immersed in water prepared in a large bowl to remove heat from the potassium hydroxide aqueous solution 21. Next, the potassium hydroxide aqueous solution 21 is placed in a large flat-bottomed beaker 23 and placed on a solution stirring device (not shown) with a hot plate. Then, a stirrer (not shown) is placed in the large flat-bottomed beaker 23, and the liquid temperature is set to 80°C and the rotation speed of the stirrer is set to 600 rpm.
Enter 0. Once etched to a sufficient depth, the etching is stopped, and the SiO2/Si substrate 20 is taken out of the potassium hydroxide aqueous solution 21 and washed with pure water to completely remove the potassium hydroxide aqueous solution 21. Figure 4(k) (
l) shows the SiO2/Si substrate 20 after cleaning,
The SiO2/Si substrate 20 in this state after cleaning is observed with an optical microscope to confirm the state of the SiO2 mask etched surface of the substrate and the like.

Next, as shown in FIGS. 5(m) and (n),
A magnetic material 23 is embedded in the groove 22 of the SiO2/Si substrate 20. There are the following four methods for embedding the magnetic material 23. The first method is to put ferrite magnetic powder with a diameter of 1 to 5 μm into the groove 22, cover the groove 22 with a separately prepared Si substrate, and apply pressure to increase the density of the hard ferrite magnetic powder. It's a method. In order to increase the density of magnetic powder, there are two methods: inserting magnetic powder while applying a magnetic field perpendicular to the substrate, applying vibration,
There is a method of sintering by leaving the material in an electric furnace heated to about 0° C. for about 10 hours. In the final sintering method, sintering fills the gaps between the magnetic powders and reduces the apparent volume. Therefore, 1
After sintering, it is necessary to insert magnetic powder again. After that, the magnetic powder inserted a second time can also be sintered. Furthermore, there is also a method of repeating the same process from the second time onwards.

The second method is to use SiO in a vacuum thin film forming apparatus.
2/Si substrate 20 is set, sputtering is performed using a sputtering material (hard ferrite) as a target, and the magnetic material 23 is embedded in the groove 22, which is the same as the normal sputtering method. The third method is to apply a coating agent containing magnetic powder used for magnetic tapes, magnetic diskettes, etc. to SiO2.
/Si substrate 20 is poured into the groove 22, and volatile substances are vaporized to increase the volume ratio of the magnetic powder. For more information,
Add ferrite magnetic powder to an organic binder liquid and mix thoroughly so that the magnetic powder is evenly distributed. However, to prevent air bubbles from forming during mixing,
You need to be very careful. Furthermore, the mixing ratio of magnetic powder greatly affects the strength of the magnetic field. The magnetic field strength changes approximately in proportion to the mixing volume ratio, and when the magnetic field strength is maximum, it is equal to the magnetic field strength when only the mixed magnetic powder is oriented. Next, the binder liquid mixed with magnetic powder is mixed with SiO2/
Drop it into the groove 22 of the Si substrate 20 until it slightly overflows the groove 22. Next, SiO2/Si substrate 2
0 on a hot plate and heated to about 50° C. to vaporize the volatile substances contained in the binder liquid and relatively increase the volume ratio of the magnetic powder. A fourth method is to deposit a magnetic metal material into the groove 22 by electroplating and fill it with the metal magnetic material.

Next, in any of the above four methods, as shown in FIG. 5(m), unevenness occurs on the surface of the magnetic material 23, so as shown in FIG. 6(o), SiO
2/ Polish the substrate surface of the Si substrate 20 to make it flat. Next, as shown in FIG. 6(p), the SiO2/Si substrate 20
A protective film 24 made of SiO2 or the like is formed thereon. In detail, approximately 1.0μ is formed using the CVD method (chemical vapor deposition method).
m SiO2 film is formed on the SiO2/Si substrate 20, or a thin film is formed on the SiO2/Si substrate 20.
The protective film 24 is formed by pasting it on the surface or applying resin, paint, or the like.

Next, the magnetic body 23 is magnetized by a magnetizer. Specifically, as shown in FIG. 6(q), the SiO2/Si substrate 20 is sandwiched between magnetic poles extending along the substrate surface, and the magnetic body 23 is magnetized by a magnetic field in a direction perpendicular to the substrate surface. Through the above steps, a SiO2/Si substrate 20 having a predetermined pattern of magnetized magnetic material is manufactured, that is, as shown in FIG.
A magnetic scale 25 shown in is manufactured.

Note that one of the conditions for the material of the metal film 12 is the temperature (900 to 110
0° C.), and in addition to the above-mentioned Cr, Ti, Ni, Au, Au-Cr alloy, Ni-Cr alloy, etc. can be used as the metal film 12. Ti,N
As the respective etching solutions when using Au, a solution of SHNO3+HF, a solution of HCl+HNO3, and an aqueous iodopotassium solution are known.

[0025]

According to the present invention, since the metal film is formed by a photoetching process in the first step, a predetermined pattern can be etched with high positional accuracy in the second step, and the magnetic pattern position accuracy can be improved. Furthermore, different magnetic patterns (codes) can be manufactured at once by simply exchanging photolithography mask patterns.

Furthermore, since the magnetic material is magnetized after being embedded in the etched groove, it is possible to apply strong magnetization to the magnetic material, and as a result, a strong magnetic field strength can be obtained during position detection. The S/N ratio of the output signal can be increased. Furthermore, since the etching used in the first and second steps can be performed only by so-called wet etching, it is possible to eliminate the need for dry etching equipment such as RIE, which is generally expensive. Cost can be reduced.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the first step of an embodiment of the magnetic pattern manufacturing method according to the present invention, in which (a) is a silicon substrate preparation step, (b) is a metal film forming step, and (c) is a The resist coating process is shown.

FIG. 2 is a diagram showing the next step after the step shown in FIG. 1, in which (d) is an exposure step, (e) is a development step, (f) is a metal film etching step, and (g) is a resist removal step. shows.

FIG. 3 is a diagram showing a step subsequent to the step shown in FIG. 2, in which (h) shows a protective film forming step, (i) a metal film removing step, and (j) a Si part etching step.

4 is a diagram showing an etching state confirmation step following the step shown in FIG. 3, where (k) is a cross section perpendicular to the substrate surface;
1) shows a cross section parallel to the substrate surface.

FIG. 5 is a diagram showing a magnetic material embedding step that is the next step after the step shown in FIG. 4, where (m) shows a cross section perpendicular to the substrate surface, and (n) shows a cross section parallel to the substrate surface. ing.

FIG. 6 is a diagram showing the next step after the step shown in FIG. 5, in which (o) is a substrate surface polishing step, (p) is a protective film forming step, and (q) is a magnetic material magnetization step. show.

FIG. 7 is a diagram showing a pattern of a magnetic scale manufactured by the steps shown in FIGS. 1 to 6.

FIG. 8 is a schematic diagram of an apparatus to which a conventional magnetic pattern manufacturing method is applied.

[Explanation of symbols]

11 Si substrate (substrate material) 12 Metal film 18 SiO2 film (protective film) 22 Groove (etched groove) 23 Magnetic material

Claims (1)

[Claims] 1. A first step of selectively covering the surface of a substrate material with a metal film using a photo-etching process, and then forming a protective film on the exposed surface of the substrate material, and removing the metal film. a second step of etching the exposed portion of the substrate material to form a predetermined pattern on the substrate material; and a third step of embedding a magnetic material into the etched grooves of the pattern formed in the second step. A method for manufacturing a magnetic pattern, comprising the steps of: and a fourth step of magnetizing the magnetic material.