JP3124873B2 - Thermal head and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head used in a thermal printer, and more particularly to a thermal head excellent in printing efficiency and thermal responsiveness, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In general, a thermal head mounted on a thermal printer is used in a state of being in contact with a recording medium such as an ink ribbon or thermal paper, and a plurality of heating resistors are linearly mounted on a substrate. In a thermal printer, heat-sensitive recording paper is colored by selectively energizing any one of the heating resistors based on desired print information to heat the heating resistor, and in a thermal transfer printer, The printing is performed by partially melting the ink of the ink ribbon and transferring the ink to plain paper.

FIG. 4 shows a conventional general thermal head. In this thermal head, a heat insulating layer 2 made of glass glaze is formed on a substrate 1 made of an insulating material such as alumina. The heat retaining layer 2 is formed such that its upper surface is formed in an arc shape. This thermal insulation layer 2
A plurality of heating resistors 3 are formed in a straight line on the upper surface 2a. That is, the heating resistor 3 is
After the material of the heating resistor 3 made of Ta ₂ N, TaSiO _2, or the like is deposited on the surface of the heat retaining layer 2 by vapor deposition or sputtering, the material is divided into a plurality of pieces in the direction perpendicular to the paper surface of FIG. It is formed. Further, on one side (the left side in FIG. 4) of the upper surface of the heating resistors 3, a common electrode 4 a connected to each heating resistor 3 is laminated, and the other side of each heating resistor 3 ( On the right side in FIG. 4, individual electrodes 4 b for independently supplying current to the respective heating resistors 3 are stacked. The common electrode 4a and the individual electrode 4b are, for example,
It is made of Al, Cu or the like, and is formed into a pattern of a desired shape by etching after being deposited by vapor deposition, sputtering or the like. Then, the heating resistor 3 and the common electrode 4a
The heat generating portion 6 is formed on the top of the heat insulating layer 2 by the individual electrode 4b.

Further, the heating resistor 3 and the common electrode 4
a, individual electrode 4b, exposed substrate 1 and heat insulating layer 2
The surface of the heating resistor 3 and the electrodes 4a, 4b
A protective layer 5 made of SIALON or the like is formed to protect the OLED from oxidation and abrasion. This protective layer 5
All the surfaces of the electrodes 4a and 4b other than the terminal portions are covered.

[0005]

In the thermal head as shown in FIG. 4, when the heat insulating layer 2 made of glass glaze is formed thin, the thermal storage of the thermal head decreases by the thinned heat insulating layer 2. In addition, thermal responsiveness is improved, and high-speed printing can be performed. However, since the height from the upper surface of the substrate 1 to the heat generating portion 6 is reduced, the pressure contact with the ink ribbon is weakened, so that the printing efficiency is reduced and the power consumption is increased.

Conversely, if the heat-insulating layer 6 is formed thick to protrude the heat-generating portion 6 high, the heat-generating portion 6 is intensively pressed against the ink ribbon, so that the printing efficiency is improved and the power consumption is reduced. Can be done. However, the thick heat insulating layer 2 has a problem that the heat storage amount increases, the thermal responsiveness is impaired, and the heat insulating layer 2 becomes unsuitable for high-speed printing.

In recent years, the printing speed of a thermal transfer printer has been significantly increased to 100 to 150 cps. As a result, the heat conductivity of the current alumina substrate is insufficient, so that heat is not sufficiently released. In some cases, the print quality was reduced due to the crushing, and printing stains were generated in which the ink was rubbed and the tail was pulled long (tailing).

The present invention overcomes the above-mentioned problems, has good printing efficiency, is excellent in thermal responsiveness, and reliably prevents deterioration of print quality and generation of print stains even when continuous printing is performed at high speed. It is an object of the present invention to provide a thermal head which can maintain high reliability and can be easily manufactured, and a method for manufacturing the same.

[0009]

[0010]

[0011]

[0012]

[MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
The thermal head according to claim 1 is provided on the surface of the substrate.
A heat insulation layer is formed, and a plurality of heating resistors are formed on the heat insulation layer.
And an individual electrode connected to each of these heating resistors and
Form a common electrode, at least the heat insulation layer, heat generation resistance
Protective layer covers body, individual electrode and common electrode
Wherein the substrate is a single crystal
Heating resistor on the top surface of the substrate, made of silicon
A substantially trapezoidal mesa is formed at a position corresponding to the
In addition, the heat insulation layer is mainly composed of a low oxide of Si and a transition metal, and is formed in a columnar shape.

Preferably, the heat insulating layer formed in the columnar material is densified by high-temperature heat treatment and has a reduced compressive stress.

In the method of manufacturing a thermal head for manufacturing a thermal head substrate and a heat insulating layer according to the first aspect of the present invention, the surface of a substrate made of single-crystal silicon having a (100) crystallographic orientation may be made of silicon oxide. Forming a mask layer, forming a mask pattern on the mask layer, forming a mesa by anisotropically etching the substrate, etching and removing the residual mask layer,
A step of immersing the substrate in an anisotropic etching solution to change the taper angle of the mesa to approximately 25 °; a step of immersing the substrate in an isotropic etching solution to form a mesa corner portion into a round shape; laminating a heat insulating layer made of low thermal conductivity material on the substrate, coercive by heat-treating the substrate at a high temperature
The method includes a step of removing internal stress of the thermal layer .

[0015]

According to the present invention described above, by utilizing the good photolithographic processability of a substrate made of single-crystal silicon, a substantially pedestal capable of applying a large pressing force to the upper surface of the substrate in a shape that does not hinder subsequent processes. If a mesa having a shape is formed, and the heat generating portion is disposed on the mesa, the ink ribbon can be intensively pressed against the mesa, so that the printing efficiency can be improved. Further, by forming the heat insulating layer as a columnar film mainly composed of low oxides of Si and Ta, it is possible to make the thermal conductivity lower than that of the conventional one, and to further improve the printing efficiency. Can be. In addition, the thermal conductivity of a substrate made of single crystal silicon is approximately eight times higher than that of a conventional alumina substrate, so that the thermal responsiveness is improved, and high-quality printing results are obtained even when high-speed continuous printing is performed. Can be obtained. Further, by performing heat treatment on the heat insulating layer at a high temperature, heat resistance can be stabilized, adhesion between the heat insulating layer and the mesa can be increased, and mechanical reliability can be improved. And it can be easily manufactured based on the workability of the substrate,
Cost can also be reduced.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows an embodiment of a thermal head according to the present invention.

In this embodiment, the substrate 11 is made of single crystal silicon, particularly single crystal silicon having a plane orientation of (100). On the upper surface of the substrate 11, a mesa 11a having a substantially trapezoidal cross section is formed so as to protrude.
A heat insulating layer 12 made of a low thermal conductive material is laminated on the upper surface of the substrate. On the upper surfaces of the substrate 11 and the heat insulating layer 12 formed as described above, the heat generating resistor 13 and
The electrodes 14a and 14b and the protective layer 15 are formed.

Next, the structure of the thermal head according to the present embodiment will be described together with a method of manufacturing the thermal head with reference to a flowchart showing the steps of manufacturing the substrate 11 and the heat insulating layer 12 of the thermal head shown in FIG.

In FIG. 2, as the substrate 11 of this embodiment, a substrate made of single-crystal silicon having a plane orientation of (100) is used (step ST1). The substrate 11 made of single crystal silicon has a thermal conductivity about eight times that of a conventional alumina substrate.

Next, the substrate 1 made of single crystal silicon
1 is thermally oxidized to form a silicon oxide layer 17 of about 1 μm.
(Step ST2).

Next, a mask pattern of a photoresist is formed thereon, and the silicon oxide layer 17 is etched with a buffered hydrofluoric acid solution to form a mask 18 for forming a mesa (step ST3). At this time, the width of the mask 18 is determined by the following steps ST4 and ST4.
In 5, when the height of the mesa 11 a is set to approximately 30 μm and the taper angle is set to approximately 25 °, the width is formed so that the heat generating portion 16 can be formed in a subsequent process.

Next, the substrate 11 on which the mask 18 is formed is immersed in a hot aqueous solution of KOH, and the substrate 11 is anisotropically etched.
1a is formed (step ST4). According to this anisotropic etching, the angle (taper angle) α between the virtual surface extending upward from the slope of the side surface of the mesa 11a and the upper surface of the substrate is formed to be approximately 55 °.

Next, the residual mask 18 on the mesa 11a
a by etching with a buffered hydrofluoric acid solution,
The substrate 11 is immersed in an anisotropic etching solution composed of the hot aqueous KOH solution, and the taper angle α of the slope of the mesa 11a is further reduced from approximately 55 ° to approximately 1/2 of approximately 2
The angle is changed to 5 ° (step ST5). Mesa like this
11a to make the taper angle α of the slope approximately 25 °
During the photolithography process during thermal head manufacturing.
Pattern unevenness of the resist coating film
Deterioration of processing accuracy, disconnection of patterns, and short circuit failures occur frequently
Can be prevented.

Next, the substrate 11 is immersed in an isotropic etching solution composed of a mixture of hydrofluoric acid (volume ratio 1): nitric acid (volume ratio 8): acetic acid (volume ratio 1) and shaken. By performing isotropic etching in this manner, the mesa 11a is formed.
Are formed by dropping the corner of each corner (step ST6).

By the processing steps up to step ST6, the surface of the substrate 11 is formed into a curved curve with smooth corners.
The shape is such that subsequent film formation of each upper layer portion can be performed with good yield.

Thereafter, a black film made of a low thermal conductive material mainly composed of a low oxide of Si and a transition metal is formed on the substrate 11 by an Ar + O 2 reaction using an alloy target mainly composed of Si and Ta. A film is formed by reactive sputtering at a gas pressure set at about 1 Pa or higher, and a columnar heat insulating layer 12 having a compressive stress is laminated to a thickness of about 25 μm.
Then, the substrate 11 on which the heat insulating layer 12 is laminated is annealed at about 800 ° C. using a high-temperature furnace in a vacuum or gas atmosphere (step ST7). In the present invention, "pillar
"Material" means that the film constituting the layer develops in a columnar shape with respect to the substrate
Generally refers to a columnar set when forming a thin film.
Weaving ”or“ columnar structure ”
Means

The heat insulating layer 12 thus formed in a columnar shape
Has a high thermal insulating property and improves the printing efficiency. In addition, although the compressive pressure acts on the inside of the heat insulating layer 12 having a columnar shape, the columnar material of the heat insulating layer 12 is densified by the subsequent high-temperature annealing, and the compressive stress is reduced. This contributes to improving the accuracy of subsequent pattern forming. Moreover,
The heat resistance of the heat insulating layer 12 can be improved, and the reliability of adhesion to the heat insulating layer can be made extremely high.

Further, a thermal head is formed by disposing a heating resistor 13, a power supply 14, a protective layer 15, and a heating section 16 at desired positions in the same manner as in the prior art.

That is, the heating resistors 13 are formed in the mesa 11a in a linearly aligned manner. The heating resistor 13 is formed by applying the material of the heating resistor 13 made of Ta ₂ N or the like to the surface of the heat insulating layer 12 by vapor deposition or sputtering, and then etching the material by photolithography. Things.
A common electrode 14a connected to each heating resistor 13 is laminated on one side of the upper surface of each heating resistor 13, and each heating resistor 13 is provided on the other side of each heating resistor 13.
3 are individually laminated with individual electrodes 14b for conducting current independently. The common electrode 14a and the individual electrode 14b are made of, for example, Al, Cu, or the like, and are formed in a desired shape by etching after being deposited by vapor deposition, sputtering, or the like.

Further, on the surfaces of the heat generating resistor 13, the common electrode 14a, the individual electrode 14b, the exposed substrate 11 and the heat insulating layer 12, approximately 5 protecting the heat generating resistor 13 and the electrodes 14a, 14b are provided. A protective layer 15 having a thickness of about 7 μm is formed, and this protective layer 15 covers all surfaces of the electrodes 14a and 14b except for the terminal portions.

Next, the operation of the thermal head of this embodiment will be described.

In this embodiment, the substrate 11 is made of single-crystal silicon having excellent workability as compared with a conventional alumina substrate, especially single-crystal silicon having a plane orientation of (100). Can be formed in a substantially trapezoidal shape capable of providing a large pressing force by the single crystal silicon, and the printing efficiency can be remarkably improved. Furthermore, the heat insulation layer 12
Is formed of a low heat conductive material, particularly a material mainly composed of a low oxide of Si and a transition metal, so that the heat insulating property is large and the heat storage amount is small, so that the printing efficiency can be further improved. . As a result, power consumption during printing can be reduced. Further, the single crystal silicon forming the substrate 11 and the mesa 11a has a thermal conductivity about eight times higher than that of a conventional alumina substrate and has excellent heat dissipation, so that the thermal response as a thermal head is large. Be improved. Accordingly, high-speed printing can be performed with high quality, and even if continuous high-speed printing is performed over a long period of time, there is no occurrence of crushing of printing or printing stain due to tailing.

On the other hand, the single crystal silicon, which is the material of the substrate 11, has processing easiness by the photolithography method, so that the mesa 11a can be processed into a free shape. In the method of the present invention, the shape of the mesa 11a
Since the heat insulating layer 12 and the like formed sequentially on the upper surface of the thermal head are formed in a shape that can be easily coated, the thermal head can be easily manufactured, the yield can be improved, and the cost can be reduced. it can.

It should be noted that the present invention is not limited to the above-described embodiment, and can be modified as needed. For example, utilizing the ease of photolithographic processing of a single crystal silicon substrate, the mesa 11 can be easily formed in a plurality of steps 11a and 11b as in the thermal head shown in FIG. Can be.

[0036]

As described above, the thermal head and the method of manufacturing the same according to the present invention are constructed and operated. Therefore, by utilizing the good photolithography processability of the substrate made of single crystal silicon, the thermal head and the method of manufacturing the same can be used. Since a mesa with a shape that does not hinder the processing step and can apply a large pressing force can be formed with high precision, the heating section is arranged on this mesa, so that the ink ribbon can be intensively pressed. And the printing efficiency is remarkably improved. In addition, the thermal insulation layer is made of a black film-like low thermal conductive material containing Si and a low oxide of transition metal as main components, and the intentionally formed columnar film has lower thermal conductivity than the conventional glass glaze. Show,
Printing efficiency can be further improved.

Further, since the thermal conductivity of a substrate made of single crystal silicon is about eight times as large as that of a conventional alumina substrate, the thermal response is remarkably improved even when high-speed printing is performed, and continuous printing is performed. However, the printing is not crushed or the printing stain due to the tailing does not occur.

Further, by heat-treating the heat-retaining layer at a high temperature, the warpage of the substrate is eliminated, the heat resistance is stabilized, the adhesion between the heat-retaining layer and the mesa is increased, the mechanical reliability is significantly increased, and the printing life is prolonged. This has the effect of making the conversion possible.

Further, based on the easiness of processing the substrate, each processing step of the thermal head can be easily performed, so that the manufacturing can be facilitated and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a thermal head according to the present invention.

FIG. 2 is a process diagram showing a manufacturing process of a substrate and a heat insulating layer of the thermal head of the present invention.

FIG. 3 is a sectional view showing another embodiment of the thermal head of the present invention.

FIG. 4 is a sectional view showing a conventional thermal head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Substrate 11a Mesa 12 Heat insulation layer 13 Heating resistor 14a Common electrode 14b Individual electrode 15 Protective layer 16 Heating part 17 Silicon oxide layer 18 Mesa forming mask 18a Residual mask

Continuation of the front page (56) References JP-A-63-257653 (JP, A) JP-A-62-131562 (JP, A) JP-A-4-188648 (JP, A) JP-A-4-246552 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B41J 2/335

Claims (3)

(57) [Claims] A heat insulating layer is formed on a surface of a substrate, and the heat insulating layer is formed on the heat insulating layer.
On the top surface of the layer, a plurality of heating resistors, and each of these heating resistors
Form individual electrodes and common electrodes connected to
Both the heat insulating layer, heating resistor, individual electrode and common electrode
On the thermal head with the top surface covered with a protective layer.
And the substrate is formed of single crystal silicon.
In the position corresponding to the heating part of the heating resistor on the top surface of the board.
A trapezoidal mesa is formed and the heat insulating layer
Is composed mainly of a low oxide of Si and a transition metal,
Thermal head characterized by being formed
De. 2. The heat insulating layer formed on the columnar material has a high temperature.
And compressive stress reduced by heat treatment
The thermal head according to claim 1, wherein
Good. 3. A substrate for a thermal head according to claim 1.
Method for manufacturing a thermal head for manufacturing a thermal head and a heat insulating layer
From the single crystal silicon whose surface crystal orientation is (100)
A mask layer made of silicon oxide on the surface of a substrate
Process to form a mask pattern on the mask layer
Process to form a mesa by anisotropically etching the substrate
Process to remove the remaining mask layer by etching,
Substrate is immersed in an anisotropic etchant to taper the mesa
Changing the angle to approximately 25 °,
Dipping into a messing solution to form rounded mesa corners.
Forming process, heat insulation made of low thermal conductive material on the substrate
The process of stacking layers, heat treating the substrate at a high temperature, and keeping the layer warm
A step of removing internal stress of the substrate.
-Manufacturing method of multiple heads.