JP2002056587A - Head for high density recording and recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain higher density by thermal recording by using a head having a heater in nanometer-order size. SOLUTION: A head 100 has a cantilever structure, and a heater 120 in nanometer-order size is integrated at the top of the head 100. The heater 120 is formed into a pyramid protrusion and can directly heat a recording medium 200 by the metal wiring in the heater. The wiring is made thin near the top end of the protrusion of the heater 120, and when the metal wiring is energized, the thin part is locally heated to act as a heater. As for the method for recording in the recording medium 200, the head can be used for both of the magnetic recording type and phase transition type.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for recording data, and more particularly to a technique for recording by heat using a minute heater.

[0002]

2. Description of the Related Art Magneto-optical disks have been used for more than 10 years and have been used as memories in various fields. In a commonly used magneto-optical device, a recording magnetic medium is heated by a laser beam, and the magnetization direction of the magnetic medium is changed by an electromagnetic coil. Recording / erasing occurs only in a portion where the temperature of the magnetic film is heated by the laser beam.
When laser light is used, the recording density is determined by the spot size determined by the diffraction limit of light.

[0003] On the other hand, micromachining technology has been useful for the development of various microelectromechanical systems. This field of application is wide and is used for sensors, analytical instruments, manipulators, etc. in a wide variety of fields such as science, biotechnology, medical care, environment, and machinery. The use of nano-scale mechanics, in which the size of a micro-machine, which has conventionally been a micro-scale, is further reduced, can further improve the performance of a conventional micro-electro-mechanical system. Specifically, a 10-fold improvement in performance can be expected by reducing the size of the system to a single-digit sensitivity and response speed. Further development and use of the developed nanoscale ultra-fine processing technology can realize devices with higher sensitivity and higher speed, and can be applied to high-density recording devices.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to pay attention to the fact that optical recording is essentially performed by heat,
Using a head with a nanometer-order heater,
The goal is to achieve higher density by performing recording with heat.

[0005]

To achieve the above object, the present invention provides a high-density recording head for recording by applying heat to a recording medium to cause a change in the recording medium. Having a protrusion protruding from the recording medium, and the conductor is thin near the tip of the protrusion, and when the conductor is energized, the thinned conductor portion is locally heated. And a high-density recording head. By using this head, high-density recording can be performed on a recording medium.

Also, a metal coil is provided around the projection, and a magnetic flux can be applied to the recording medium by energizing the metal coil. Magnetic recording can be performed by using this head. it can. The conductor is a metal,
A thermocouple is formed between the dissimilar metal and the tip of the protruding portion. A temperature change can be detected by the thermocouple, so that data recorded by a phase change can be read.

In such a high-density recording head, the projections may be made of silicon oxide, and may have a conductor inside the silicon oxide. The method of manufacturing a high-density recording head includes a step of etching a silicon substrate to form a depression; a step of oxidizing the silicon substrate by heating; a step of forming an insulating film on the silicon substrate; A metal wiring by vapor deposition and a molding by etching. The method may further include a step of forming a hole at the tip of the projection and depositing a metal film, and forming a thermocouple at the tip of the projection. This manufacturing technology
This is an application of micromachining technology, and it is possible to manufacture multiple heads at once.

Using these high-density recording heads, a recording unit having at least one high-density recording head, a driving unit for rotating a recording medium at high speed, and a control unit for performing recording control are provided. A recording apparatus that performs recording on the rotating recording medium by heating the recording medium with the high-density recording head can be configured. High-speed writing can also be performed by writing in parallel using a recording unit having a plurality of heads.

[0009]

Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an example of a head structure according to the present invention. As shown in FIG. 1, the head 100 has a cantilever structure. A heater 120 of the order of nanometer is integrated at the tip of the head 100. The heater 120 is formed as a pyramid-shaped protrusion, and includes a conductor such as a metal inside. By applying a current to the internal conductor, the recording medium 200 can be directly heated. As a recording method for the recording medium 200, both a magnetic recording type and a phase change type can be used.

In magnetic recording, a heater 12 having a size of several tens of nanometers is used.
By using 0 to heat the recording magnetic medium 200 and changing the magnetization direction of the magnetic medium with an electromagnetic coil, writing / reading of nanometer-sized bits is performed at high speed. The feature of this recording method is that the bit size is determined by the size of the heater 120. If the heater size is reduced, the recording density can be improved in principle compared to the case where light is used. Reading is performed using a separately formed magnetic head, or reading is performed based on the magnitude of the magnetic force between the magnetic material at the tip of the head and the magnetic medium. In magnetic recording, it is necessary to perform a contact operation during recording and a non-contact operation during reading.

[0011] Recording by phase change can also be performed using a head having a heater. For example, the recording medium 200
Recording can be performed by heating the above phase change film such as GeSbTe to a temperature higher than the melting point by the heater 120 and changing the phase from a crystalline phase to an amorphous phase. It can be erased by heating to crystallization temperature. Using the heater 120, the difference in thermal conductivity and thermal diffusivity between the crystallized phase and the amorphous phase can be measured, and a read operation can be performed. Specifically, the heater 120 is rapidly heated to a temperature lower than the crystallization temperature, and a temperature change due to a difference in heat conduction or the like of the recording medium is measured using a nano-sized thermocouple formed at the tip of the heater 120. The thermomagnetic readout requires a non-contact operation between the head and the medium, but the phase change type has a feature that a contact operation is sufficient. The phase change can be detected by another method, for example, by applying a voltage between the heater 120 and the recording medium 200 and detecting a current flowing between the heater 120 and the recording medium 200.

FIG. 2 (a) shows an example in which a plurality of heads 100 with heaters are used to improve the recording speed and a structure capable of performing parallel processing. In the head structure shown in FIG. 2A, each head 100 is in the form of a cantilever, and has a heater 120 at the tip. A coil 130 is provided around each heater. 2B, the configuration of the coil 130 around the heater 120 can be understood. By applying a current to the coil 130 from the electrodes 144 and 146, heating by the heater 120 and application of a magnetic field are enabled. Each heater 1
20 is applied to electrodes 142 and 148 (FIG.
In the case of the configuration of the heater shown in (c), the heater is connected to the wiring on the back side of the substrate 160). In the circuit section 150 on the substrate 160, a circuit for performing electrical control of the head can be formed. FIG. 2 (c)
A specific configuration example of the heater 120 is shown. The protrusion is SiO
₂ and SiON acting as an insulating film. Heater 12
The heating portion 0 is made of a thin metal (here, Pt / Cr) wiring. The wiring is thin near the tip of the protrusion,
By energizing the metal wiring, the thinned portion is locally heated, thereby fulfilling the function of a heater. The tip of the protrusion form in the heater 120 is:
Dissimilar metals are joined to form a thermocouple. With this thermocouple, heating and temperature measurement can be alternately performed by changing the magnitude of the current in a pulsed manner, and the heating in the heater 120 can be monitored. The metal used as the thermocouple is composed of chemically resistant Pt and Ni. Further, Cr is used to enhance the adhesion between Si and Pt. When it is not necessary to form a thermocouple in the heater 120, there is no need to connect Pt and Ni, which is a dissimilar metal, and a Pt layer may be formed to allow current to flow through the heater section.

<Method of Manufacturing Head> FIG. 3 shows a process of manufacturing the head 100 including the heater 120 shown in FIG.
Since the head 100 is formed by micro-machining, it can be formed by batch processing. The production procedure is described with reference to FIG.
The description will be given in order below. As shown in FIG.
First, the Si substrate 110 is etched to process pyramid-shaped depressions. Then, as shown in FIG.
The surface of the Si substrate 110 is thermally oxidized at 950 ° C. 950
In the thermal oxidation at ° C., the thickness of the SiO ₂ film 111 becomes thinner as the tip of the projection becomes closer. For this reason, as explained later,
Etching the protrusion tip can open a hole with a diameter on the order of nanometers. Next, as shown in FIG.
An SiON film 112 is formed on a Si substrate 110. Thereafter, as shown in FIG.
The t / Cr layer 113 is deposited. Next, as shown in FIG. 3E, the Si substrate 110 is etched from the back surface. As shown in FIG. 3F, when the tip of the projection comes out, a hole is made here. Finally, as shown in FIG. 3G, a Ni layer 114 is deposited to form a thermocouple with Pt / Cr.

FIG. 4 shows an SEM photograph of the actually manufactured head. FIG. 4A is a photograph of a minute opening at the tip of the SiO ₂ protrusion. In this photo, Cr
It can be seen that the micro projections are attached. Where N
i is deposited to form a thermocouple. FIG.
(B) is a photograph of the cantilever tip viewed from above. A heater is formed at the bottom of the pyramid. A step due to SiO ₂ can be confirmed inside the depression.

<Recording Apparatus> FIG. 5 shows a configuration example of a recording apparatus 300 using the above-described plurality of heads 100. In this system, the floating disk 320 (recording medium 200) is formed by electrostatic levitation and electrostatic levitation by the rotating electrode 340.
A mechanism is used to levitate and rotate at high speed. In addition, a structure in which a plurality of heads 100 are arranged and it is not necessary to perform a tracking operation is adopted. The drive system for driving the recording medium (disk) is not limited to the electrostatic levitation configuration shown in the figure, but may be any that can be moved relative to the head.

[0016]

According to the present invention, recording is performed by directly heating a recording medium by a head having a minutely configured heater, so that high-density recording can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a head of the present invention.

FIG. 2 is a diagram showing an example of a specific configuration of a head according to the present invention.

FIG. 3 is a diagram illustrating an example of a method for manufacturing a head according to the present invention.

FIG. 4 is a view showing a photograph of a manufactured head.

FIG. 5 is a diagram illustrating a configuration example of a recording apparatus using a head having a heater according to the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 100 head 110 silicon substrate 111 SiO ₂ layer 112 SiON film 113 Pt / Cr layer 114 Ni layer 120 heater 130 coil 200 recording medium 300 recording device 320 floating disk 340 electrode for rotation

Claims (7)

[Claims] 1. A high-density recording head for recording by applying heat to a recording medium to cause a change, comprising: a projection that has a conductor inside and protrudes from the recording medium; The high-density recording head according to claim 1, wherein the conductor near the tip of the protrusion is thin, and when the conductor is energized, the thin part is locally heated. 2. The high-density recording head according to claim 1, wherein a metal coil is provided around the projection, and a magnetic flux is applied to the recording medium by energizing the metal coil. High-density recording head. 3. The high-density recording head according to claim 1, wherein the conductor is a metal, and a thermocouple is formed at a tip of the protrusion with a different kind of metal. A high-density recording head characterized in that a temperature change can be detected by a pair. 4. The high-density recording head according to claim 1, wherein said projection is made of silicon oxide, and has a conductor inside the silicon oxide. 5. A method for manufacturing a high-density recording head, comprising the steps of: etching a silicon substrate to form a dent; heating; oxidizing the silicon substrate; and forming an insulating film on the silicon substrate. And a step of forming a conductor on the silicon substrate by vapor deposition. 6. The method for manufacturing a high-density recording head according to claim 5, wherein the conductor is a metal, and further comprising a step of forming a hole at a tip of the projection and depositing a metal film. Forming a thermocouple at the tip of the head. 7. A recording apparatus using the high-density recording head according to claim 1, wherein a recording unit having at least one high-density recording head and a recording medium are rotated at a high speed. A recording apparatus comprising: a driving unit; and a control unit that performs recording control, and performs recording on the recording medium that rotates at a high speed by heating the recording medium with a high-density recording head.