JP2006015582A - Thermal head and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a thermal head which can improve the operation characteristic of the thermal head as much as possible. <P>SOLUTION: A glaze layer 2 is formed to include a glass ceramics. After a heating resistor layer 3 is formed on the glaze layer 2 next, the heating resistor layer 3 is heated. The crystallinity of polycrystalline silicon which constitutes the heating resistor layer 3 is thermally relaxed by this heat treatment, and at the same time impurities are prevented from being diffused from the glaze layer 2 to the heating resistor layer 3. In consequence, the crystallinity of the polycrystalline silicon is greatly improved. The resistance characteristic of the heating resistor layer 3 is improved to be stable, and therefore the operation characteristic of the thermal head 10 represented by the SST characteristic or pulse resisting characteristic is improved as much as possible. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a thermal head mounted as a heat generation source in, for example, a thermal printing apparatus and the like and a manufacturing method thereof, and more particularly, to a heat storage layer (so-called glaze layer) for storing heat generated in a heating resistor layer. The present invention relates to a thermal head provided and a manufacturing method thereof.

  In recent years, thermal heads have been widely used as heat generation sources in the image forming field in which images are formed using thermal energy. A thermal head is a heating device provided with a heating resistor layer. If an image forming apparatus (for example, a thermal printing apparatus) equipped with this thermal head is used, the thermal energy generated in the heating resistor layer is used. Thus, it is possible to form (print) an image on an image forming medium (for example, a printing medium such as thermal paper).

The main part of the thermal head has, for example, a laminated structure in which a glaze layer, a heating resistor layer and electrode layer, and a protective layer are laminated in this order on a substrate. As a constituent material of the glaze layer, for example, glass is generally used from the viewpoint of easily forming the glaze layer. Further, as a constituent material of the heating resistor layer, for example, a carbide, oxide or nitride of a refractory metal is generally known. Examples of the refractory metal include tantalum (Ta), titanium (Ti), chromium (Cr), molybdenum (Mo), niobium (Nb), and tungsten (W). Recently, for example, polycrystalline silicon doped with boron (B) or phosphorus (P) is also used as a constituent material of the heating resistor layer. When the heating resistor layer is formed using this polycrystalline silicon, a semiconductor process can be used as the formation method (see, for example, Patent Documents 1 to 3).
JP 62-168375 A Japanese Patent Laid-Open No. 01-215560 JP-A-01-283161

  However, in recent years, there has been a demand for further improvement in the operating characteristics of the thermal head under the situation where the printing speed is increased and the printing precision is being accelerated. In order to improve this, several techniques have already been proposed.

  Specifically, for example, the CVD (Chemical Vapor Deposition) method is used to heat the substrate in order to improve the SST (Step Stress Test) characteristics and pulse resistance characteristics, which are typical operating characteristics of thermal heads. A technique for forming a heating resistor layer by forming a polycrystalline silicon film is known (see, for example, Patent Documents 2 and 3). The heating temperature at this time is determined based on the heat resistance of the glaze layer, and specifically is lower than the glass transition temperature of the glaze layer. According to this technology, the crystal structure of the polycrystalline silicon constituting the heating resistor layer is stabilized by thermal relaxation, and the crystallinity of the polycrystalline silicon is improved. Will improve.

Further, for example, a technique is known in which an intermediate layer that functions as a barrier for suppressing diffusion of impurities from the glaze layer to the heating resistor layer is provided between the glaze layer and the heating resistor layer ( For example, see Patent Document 4.) According to this technology, when the heating resistor layer generates heat during the operation of the thermal head, impurities contained in the glaze layer are less likely to diffuse into the heating resistor layer based on the presence of the intermediate layer. The operating characteristics of the thermal head are unlikely to deteriorate due to the diffusion phenomenon of impurities.
Japanese Patent Publication No. 06-049375

  In addition to the series of techniques described above, various approaches are being studied as techniques related to techniques for improving the operating characteristics of the thermal head.

Specifically, for example, a first glass layer is formed on a substrate using crystallized glass, and then a second glass layer is formed on the first glass layer using amorphous glass. A technique for forming a glaze layer having a large film thickness on a substrate by firing the first and second glass layers is known (for example, see Patent Document 5).
Japanese Patent Application Laid-Open No. 09-1000018

Further, for example, tantalum nitride (Ta ₂ N) is used instead of polycrystalline silicon to form the heating resistor layer, and tantalum (Ta) or silicon (Si) oxide is used instead of glass. A technique for heating the heating resistor layer at a temperature higher than the glass transition temperature of the above-described glaze layer by configuring the glaze layer is known (see, for example, Patent Document 6).
JP 05-147248 A

  By the way, in order to respond to the above-described request for improving the operating characteristics of the thermal head and to further spread the market for the thermal head, it is necessary to improve the operating characteristics of the thermal head more than ever. However, in the conventional thermal head manufacturing method, the operation characteristics represented by the SST characteristics and the pulse resistance characteristics are not sufficient from the viewpoint of market demand, and there is still room for improvement. In particular, the above-described SST characteristics and anti-pulse characteristics are factors that greatly influence the printing characteristics of a printing apparatus equipped with a thermal head. Therefore, there are various demands regarding the printing characteristics of the printing apparatus. Considering the background, there is an urgent need to establish a technique that can improve the operating characteristics of the thermal head as much as possible.

  The present invention has been made in view of such problems, and a first object thereof is to provide a thermal head having improved operating characteristics as much as possible.

  A second object of the present invention is to provide a thermal head manufacturing method capable of improving the operating characteristics of the thermal head as much as possible.

The thermal head according to the present invention includes polycrystalline silicon, and includes a heating resistor layer having a half-width of a Raman spectrum peak of 16 cm ⁻¹ or less, a heating resistor layer adjacent to the heating resistor layer, and including crystallized glass. Heat storage layer.

Since the thermal head according to the present invention includes a heat storage layer configured to include crystallized glass, for example, when the heating resistor layer formed on the heat storage layer is heated in the manufacturing process of the thermal head, The crystallinity of the polycrystalline silicon constituting the heating resistor layer is remarkably improved. Specifically, the half width of the Raman spectrum peak of the heating resistor layer is 16 cm ⁻¹ or less.

  The “crystallized glass” refers to a glass in which a crystal phase is precipitated by heat treatment (a glass in which amorphous and crystalline are mixed), specifically 30% to 100%, preferably 30% to 70%. % Refers to glass having a crystallization rate of%. This crystallization rate is a value calculated using an existing analysis method such as the Rietveld method or the Scherrer method based on the result measured using the X-ray diffraction method. Among these, a value calculated using the Rietveld method is preferable.

  The thermal head manufacturing method according to the first aspect of the present invention includes a first step of forming a heat storage layer so as to include crystallized glass, and a second step of forming a heating resistor layer on the heat storage layer. And a third step of heating the heating resistor layer.

  In the thermal head manufacturing method according to the first aspect of the present invention, in the state where the heat storage layer is formed so as to include crystallized glass, the heating resistor layer formed on the heat storage layer is heated. The crystallinity of the polycrystalline silicon constituting the heating resistor layer is improved based on the thermal relaxation action. In this case, in particular, based on the fact that the heat storage layer is formed by including crystallized glass having high heat durability, the heat storage layer is formed by including amorphous glass having low heat durability and In comparison, it is possible to heat the heating resistor layer at a higher temperature while suppressing an excessive thermal influence (for example, deformation and occurrence of cracks) on the heat storage layer. The crystallinity of silicon is significantly improved. Moreover, based on the fact that the heat storage layer is formed to contain crystallized glass that hardly diffuses impurities when heated, the heat storage layer is formed to contain amorphous glass that easily diffuses impurities when heated. Compared with the case where it is formed, impurities are less likely to diffuse from the heat storage layer to the heating resistor layer, so that the crystallinity of the polycrystalline silicon is remarkably improved also in this respect.

  The thermal head manufacturing method according to the second aspect of the present invention includes a first step of forming a heat storage layer on a substrate so as to include crystallized glass, and a heating resistor layer on the heat storage layer while heating the substrate. And a second step of forming.

  In the thermal head manufacturing method according to the second aspect of the present invention, in the state where the heat storage layer is formed so as to include crystallized glass on the substrate, the heating resistor layer is formed on the heat storage layer while the substrate is heated. Therefore, as in the thermal head manufacturing method according to the first aspect of the present invention, the crystallinity of the polycrystalline silicon constituting the heating resistor layer is improved based on the thermal relaxation effect. In particular, since it becomes possible to heat the heating resistor layer at a higher temperature while suppressing an excessive thermal influence (for example, deformation and occurrence of cracks) on the heat storage layer, the polycrystalline silicon The crystallinity of the polycrystalline silicon is remarkably improved and impurities are hardly diffused from the heat storage layer to the heating resistor layer.

In the thermal head according to the present invention, the crystallized glass preferably has a thermal expansion coefficient within a range of −5.0 × 10 ⁻⁶ / ° C. or higher and 10.0 × 10 ⁻⁶ / ° C. or lower. This kind of crystallized glass includes spodumene solid solution (LiAlSi ₂ O ₆ ), eucryptite solid solution (LiAlSiO ₄ ), petalite solid solution (LiAlSi ₄ O ₁₀ ), β-quartz solid solution (SiO ₂ ) and cordierite solid solution (2MgO · 2Al ₂ which O ₃ · 5SiO ₂₎ at least one crystalline phase of the group comprising precipitated and the like. In particular, the half width of the Raman spectrum peak of the heating resistor layer is more preferably 12 cm ⁻¹ or less.

In the thermal head manufacturing method according to the first or second aspect of the present invention, in the first step, silicon oxide (SiO ₂ ) in the range of 45 wt% to 65 wt% and 10 wt% to 30 wt%. Aluminum oxide (Al ₂ O ₃ ) in the range of not more than wt%, lithium oxide (Li ₂ O) in the range of not less than 3 wt% and not more than 10 wt%, and in the range of not less than 0 wt% and not more than 10 wt% It is preferable to produce crystallized glass by mixing magnesium oxide (MgO) and zinc oxide (ZnO) in the range of 0 wt% to 10 wt% in a powder state.

  In the thermal head manufacturing method according to the first aspect of the present invention, the heating resistor layer is formed by depositing polycrystalline silicon in the second step, and the formation of polycrystalline silicon in the third step. It is preferable to heat the heating resistor layer at a temperature in the range of the film temperature to 1100 ° C., and it is particularly preferable to form a polycrystalline silicon film by using a CVD (Chemical Vapor Deposition) method.

  In the thermal head manufacturing method according to the second aspect of the present invention, in the second step, the heating resistor layer is formed by depositing polycrystalline silicon, and the temperature is within the range of 550 ° C. to 1100 ° C. It is preferable to heat the substrate at a temperature, and it is particularly preferable to form a polycrystalline silicon film using a CVD (Chemical Vapor Deposition) method.

According to the thermal head according to the present invention, the heating resistor layer formed on the heat storage layer is heated in the manufacturing process of the thermal head, for example, based on the structural features including the heat storage layer including the crystallized glass. As a result, the crystallinity of the polycrystalline silicon constituting the heating resistor layer is remarkably improved. Specifically, the half-value width of the Raman spectrum peak of the heating resistor layer is 16 cm ⁻¹ or less. The operating characteristics represented by the SST characteristics and the pulse resistance characteristics can be improved as much as possible.

  According to the method for manufacturing a thermal head according to the first aspect of the present invention, in a state where the heat storage layer is formed so as to include crystallized glass, the heating resistor layer formed on the heat storage layer is heated. Based on the manufacturing characteristics, the polycrystalline silicon constituting the heating resistor layer is thermally relaxed and impurities are less likely to diffuse from the heat storage layer to the heating resistor layer. Since it is remarkably improved, the operating characteristics of the thermal head represented by SST characteristics and pulse resistance characteristics can be improved as much as possible.

  Further, according to the method for manufacturing a thermal head according to the second aspect of the present invention, in the state where the heat storage layer is formed on the substrate so as to include the crystallized glass, the substrate is heated and the heat storage layer generates heat. Based on the manufacturing characteristics of the resistor layer, the polycrystalline silicon constituting the heating resistor layer is thermally relaxed and impurities are less likely to diffuse from the heat storage layer to the heating resistor layer. Since the crystallinity of the polycrystalline silicon is remarkably improved, the operating characteristics of the thermal head represented by SST characteristics and pulse resistance characteristics can be improved as much as possible.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  First, the configuration of a thermal head according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 shows an external configuration (side configuration viewed from the Y-axis direction) of the thermal head 10.

  The thermal head 10 according to the present embodiment is a heat generating device mounted as a heat generating source in, for example, a thermal printing apparatus (that is, a printer). For example, as shown in FIG. 1, the thermal head 10 includes a heat generating portion 10A and a driving portion 10B for driving the heat generating portion 10A. Specifically, the heat generating portion 10A is mounted on the driving portion 10B. It has the structure which was made.

  The drive unit 10B controls the driving state of the heat generating unit 10A by energizing and driving the heat generating unit 10A. The drive unit 10B is connected to a heat sink 11 made of, for example, aluminum (Al) so that a printed circuit board (PCB) 12 partially overlaps, and one surface of the printed circuit board 12 is connected. A driver IC (Integrated Curcuit) 13 is attached to the (upper surface), and a connector 14 for external connection is attached to the other surface (lower surface). The driver IC 13 is a device for driving the heat generating portion 10A. For example, the driver IC 13 is embedded in the IC resin film 15 and further has an IC resin film by an IC cover 16 attached to one surface of the printed board 12. 15 is covered.

  The heat generating portion 10A is driven to generate heat when energized from the drive portion 10B, and is fixed to the heat radiating plate 11 of the drive portion 10B via a silicon-based adhesive 17, for example. The detailed configuration of the heat generating unit 10A will be described later.

  Next, a detailed configuration of the heat generating portion 10A will be described with reference to FIGS. 2 and 3 show an enlarged configuration of the heat generating portion 10A, FIG. 2 shows a cross-sectional configuration (cross-sectional configuration parallel to the XZ plane), and FIG. 3 shows a planar configuration (planar configuration viewed from the Z-axis direction). ). 2 shows a cross-sectional configuration along the line II-II shown in FIG.

  For example, as shown in FIG. 2, the heat generating portion 10A has a laminated structure in which a glaze layer 2, a heating resistor layer 3, an electrode layer 4, and a protective layer 5 are laminated in this order on a substrate 1. is doing.

The substrate 1 is a base for supporting the entire heat generating portion 10A, and includes an insulating material such as aluminum oxide (Al ₂ O ₃ ; hereinafter simply referred to as “alumina”).

  The glaze layer 2 is a heat storage layer for storing heat generated in the heating resistor layer 4 so that the heat does not escape to the substrate 1 and includes crystallized glass. The “crystallized glass” refers to a glass in which crystals are precipitated by heat treatment (a glass in which amorphous and crystalline are mixed), specifically about 30% to 100%, preferably about 30% to 70%. % Refers to glass having a crystallization rate of%. The reason why the crystallization rate is preferably about 30% to 70% is that, for example, if the crystallization rate is smaller than 30%, the thermal characteristics (for example, thermal expansion coefficient, glass transition temperature and deformation) in the glaze layer 2 are appropriate. This is because the molding accuracy of the glaze layer 2 may decrease if the temperature is not 70%, and is greater than 70%. This crystallization rate is a value calculated using an existing analysis method such as the Rietveld method or the Scherrer method based on the result measured using the X-ray diffraction method. Among these, a value calculated using the Rietveld method is preferable.

The crystallized glass constituting the glaze layer 2 is, for example, a value close to the thermal expansion coefficient (about 4.2 × 10 ⁻⁶ / ° C.) of the heating resistor layer 3 comprising polycrystalline silicon described later. It has a thermal expansion coefficient of That is, the crystallized glass has a heat that does not exert an excessive thermal influence (for example, deformation or generation of cracks) on the heating resistor layer 3 even when the crystallized glass expands or contracts due to thermal influence. It has characteristics, in particular has a thermal expansion coefficient of about ^{-5.0 × 10 -6 /℃~10.0×10 -6 / ℃} . Examples of this type of crystallized glass include spodumene solid solution (LiAlSi ₂ O ₆ ), eucryptite solid solution (LiAlSiO ₄ ), petalite solid solution (LiAlSi ₄ O ₁₀ ), β-quartz solid solution (SiO ₂ ), and cordierite solid solution. Examples include those in which at least one crystal phase of the group containing (2MgO.2Al ₂ O ₃ .5SiO ₂ ) is precipitated. The glass transition temperature and yield temperature of crystallized glass are, for example, the heating temperature at the time of manufacturing a thermal head described later, that is, the heating temperature after the formation of the heating resistor layer 3 or the formation temperature of the heating resistor layer 3. Is also preferably high.

The heating resistor layer 3 generates heat when energized through the electrode layer 4, and includes polycrystalline silicon (Poly-Si). Examples of the polycrystalline silicon include P-type polycrystalline silicon doped with boron (B) and n-type polycrystalline silicon doped with phosphorus (P). In particular, the half value width of the Raman spectrum peak of the heating resistor layer 3, that is, obtained by analyzing the heating resistor layer 3 (polycrystalline silicon constituting the heating resistor layer 3) using Raman spectroscopy. The full width at half maximum of the obtained Raman spectrum peak is about 16 cm ⁻¹ or less, preferably about 12 cm ⁻¹ or less.

  The electrode layer 4 is for energizing the heating resistor layer 3. The electrode layer 4 includes, for example, electrode layers 4A and 4B arranged to face each other with a predetermined gap G in the X-axis direction, and is electrically connected to the heating resistor layer 3. . Each of these electrode layers 4A and 4B includes, for example, a highly conductive material such as aluminum (Al).

The protective layer 5 prevents the heating resistor layer 3 and the electrode layer 4 from being worn or damaged due to contact with the printing medium when the thermal head 10 is used to print an image on the printing medium. Is to do. The protective layer 5 includes, for example, a material having boron (B) and phosphorus (P), and specifically uses diborane (B ₂ H ₆ ), phosphine (PH ₃ ), and the like. A boron-phosphorus compound (BP) formed by a plasma CVD (Chemical Vapor Deposition) method is included.

  In the heat generating portion 10A, for example, as shown in FIG. 3, the electrode layers 4A and 4B of the electrode layer 4 both extend in the X-axis direction, and a plurality of sets of electrode layers 4A and 4B are formed. The plurality of heating resistor layers 3 are similarly arranged in parallel in the Y-axis direction so as to correspond to the respective electrode layers 4A and 4B in the Y-axis direction. Among the electrode layers 4, one electrode layer 4A functions as a common electrode and is connected to each other between the electrode layers 4A of each set, whereas the other electrode layer 4B functions as a lead electrode. The electrode layers 4B of each set are separated from each other. The series of electrode layers 4B functioning as the lead electrodes are connected to the driver IC 13 (see FIG. 1) of the drive unit 10B, and can be energized independently of each other through the driver IC 13. In FIG. 3, the protective layer 5 is not shown and the electrode layer 4 is omitted in order to make it easy to see the positional relationship in the stacking direction (Z-axis direction) of the heating resistor layer 3 and the electrode layer 4 (4A, 4B). Layer 4 (4A, 4B) is shaded.

  In the thermal head 10, as shown in FIGS. 1 to 3, for example, in a state where the thermal head 10 is connected to the thermal printing apparatus via the connector 14 of the driving unit 10 </ b> B, the electrode is passed through the driver IC 13 based on the image pattern information. When the layer 4 (4A, 4B) is energized, the heating resistor layer 3 generates heat based on the current supplied from the electrode layer 4, thereby generating heat for printing. The heat for printing generated at this time is conducted through the protective layer 5 and finally conducted to the printing area of a printing medium (not shown).

  Next, a method for manufacturing a thermal head will be described with reference to FIGS. FIG. 4 is for explaining the flow of the manufacturing method of the thermal head. In the following, the manufacturing process of the heat generating portion 10A of the thermal head 10 will be referred to, and the forming materials of the respective components of the heat generating portion 10A have already been described and will be omitted as needed.

  When manufacturing the heat generating part 10A of the thermal head 10, first, as shown in FIGS. 2 and 3, an alumina substrate 1 is prepared as a base, and then crystallized glass is formed on the substrate 1. The glaze layer 2 is formed so as to include (FIG. 4; step S101).

In forming the glaze layer 2, for example, about 45 wt% to 65 wt% silicon oxide (SiO ₂ ), about 10 wt% to 30 wt% aluminum oxide (Al ₂ O ₃ ), and about 3 wt% to 10 wt% lithium oxide (Li ₂ O), about 0 wt% to 10 wt% magnesium oxide (MgO), and about 0 wt% to 10 wt% zinc oxide (AnO), respectively. by mixing in powder form, to produce a crystallized glass having a thermal expansion coefficient of about ^{-5.0 × 10 -6 /℃~10.0×10 -6 / ℃} , specifically spodumene solid solution (LiAlSi ₂ O _6), eucryptite solid solution (LiAlSiO _4), petalite solid solution (LiAlSi ₄ O _10), β- quartz solid solution (the group comprising SiO ₂₎ and cordierite solid solution _{(2MgO · 2Al 2 O 3 ·} 5SiO 2) At least one crystalline phase among generates crystallized glass precipitated. As a more detailed procedure for forming the glaze layer 2, for example, a glass paste produced by dissolving the above-described series of powder materials in a solvent is applied to the surface of the substrate 1, and the glass paste is dried to dry the glass paste. After the film is formed, the glass paste film is baked at a predetermined temperature for a predetermined time so that the crystallization rate is about 30% to 100%, preferably about 30% to 70%. Crystallize the membrane. The firing temperature and firing time of the glass paste film described above can be freely set as long as the crystallization rate of the crystallized glass is within the above-described range, for example.

  The reason for setting the added weight of the above-mentioned series of crystallized glass forming materials (powder materials) within the above range is, for example, as follows. That is, firstly, if the added weight of silicon oxide is less than 45% by weight, the chemical durability and heat resistance of the remaining glass phase are lowered, whereas if it is greater than 65% by weight, the main crystal phase is difficult to precipitate. Because it becomes. Second, if the added weight of aluminum oxide is less than 10% by weight, the meltability is lowered and molding becomes difficult, whereas if it is more than 30% by weight, chemical durability is lowered. Third, if the added weight of lithium oxide is less than 3% by weight, the main crystalline phase is difficult to precipitate, whereas if it is greater than 10% by weight, the chemical durability is lowered. Fourth, if the added weight of magnesium oxide is larger than 10%, the crystalline phase is difficult to precipitate in the cordierite solid solution. Fifth, if the added weight of zinc oxide is larger than 10% by weight, the crystal phase is difficult to precipitate in the petalite solid solution. Before confirmation, when the glaze layer 2 is formed, it is not always necessary to use the method of baking the glass paste. For example, instead of the method of baking the glass paste described above, an existing film forming technique is used. It may be used. In this case, it is preferable to produce crystallized glass by, for example, forming the glass paste described above or using a sol-gel method.

  Subsequently, a heating resistor layer 3 is formed on the glaze layer 2 by depositing polycrystalline silicon using, for example, a CVD method (FIG. 4; step S102). When the heating resistor layer 3 is formed, for example, a P-type polycrystalline silicon doped with boron or an n-type polycrystalline silicon doped with phosphorus is formed.

  Subsequently, the heat generating resistor layer 3 formed on the glaze layer 2 in the previous step is subjected to heat treatment, that is, the heat generating resistor layer 3 is heated (FIG. 4; step S103). When heating the heating resistor layer 3, for example, the heating resistor layer 3 is heated at a temperature of the heating resistor layer 3 (polycrystalline silicon deposition temperature) to 1100 ° C. The reason why the heating resistor layer 3 is heated within the above-described temperature range is that, for example, if the heating temperature is lower than the deposition temperature of the polycrystalline silicon, it is difficult to improve the crystallinity of the polycrystalline silicon using heat treatment. On the other hand, if the heating temperature is higher than 1100 ° C., the glaze layer 2 is likely to be excessively affected by heat (for example, deformation or generation of cracks). In particular, when heating the heating resistor layer 3, for example, the heating resistor layer 3 is heated over a period of about 10 minutes to 10 hours. The reason why the heating resistor layer 3 is heated within the above-described time range is that, for example, if the heating time is shorter than 10 minutes, it becomes difficult to improve the crystallinity of the polycrystalline silicon by using heat treatment. This is because if the time is longer than 10 hours, the productivity (manufacturing efficiency) of the thermal head 10 is extremely lowered.

  By this heat treatment, the crystal structure of the polycrystalline silicon constituting the heating resistor layer 3 is stabilized by being thermally relaxed, so that the crystallinity of the polycrystalline silicon is improved. In this case, in particular, the glaze layer 2 is formed including amorphous glass having low heat durability based on the fact that the glaze layer 2 is formed including crystallized glass having high heat durability. Compared to the case, it is possible to heat the heating resistor layer 3 at a higher temperature while suppressing an excessive thermal influence (for example, deformation or generation of cracks) on the glaze layer 2. Therefore, the crystallinity of polycrystalline silicon is remarkably improved. Moreover, based on the fact that the glaze layer 2 is formed to include crystallized glass that hardly diffuses impurities when heated, the glaze layer 2 includes amorphous glass that easily diffuses impurities when heated. Compared to the case where the impurity is formed by, the impurities are less likely to be diffused from the glaze layer 2 to the heating resistor layer 3, so that the crystallinity of the polycrystalline silicon is remarkably improved also in this respect.

  Subsequently, after the heating resistor layer 3 is heated, the heating resistor layer 3 is subjected to a cooling process, that is, the heating resistor layer 3 is cooled (FIG. 4; step S104). When the heating resistor layer 3 is cooled, for example, the heating resistor layer 3 is cooled at a cooling rate of about 0.1 ° C./min to 5.0 ° C./min. The reason why the heating resistor layer 3 is cooled within the above-described cooling rate range is that, for example, if the cooling rate is slower than 0.1 ° C./min, the productivity of the thermal head 10 is extremely reduced, while the cooling rate is reduced. This is because if the speed is higher than 5.0 ° C./min, cracks are likely to occur in the glaze layer 2 due to rapid cooling.

  Subsequently, as shown in FIGS. 2 and 3, the electrode layers 4 </ b> A and 4 </ b> B disposed on the heating resistor layer 3 so as to face each other with a predetermined gap G interposed therebetween, for example, using a sputtering method or a vapor deposition method. The electrode layer 4 is formed so as to include (FIG. 4; step S105).

  Finally, as shown in FIG. 2, by forming the protective layer 5 so as to cover the heating resistor layer 3 and the electrode layer 4 using, for example, plasma CVD (FIG. 4; step S106), the thermal head 10 heating parts 10A are completed.

  In the manufacturing method of the thermal head according to the present embodiment, the heating resistor layer 3 formed on the glaze layer 2 is heated in a state where the glaze layer 2 is formed so as to include crystallized glass. As described above, the crystallinity of the polycrystalline silicon constituting the heating resistor layer 3 is thermally relaxed, and impurities are hardly diffused from the glaze layer 2 to the heating resistor layer 3. The crystallinity of polycrystalline silicon is significantly improved. Accordingly, since the resistance characteristics of the heating resistor layer 3 are stably improved based on the marked improvement in the crystallinity of the polycrystalline silicon, the operating characteristics of the thermal head 10 typified by SST characteristics and pulse resistance characteristics are possible. As long as it can be improved.

In particular, in this embodiment, so as to form a glaze layer 2 by generating a crystallized glass having a thermal expansion coefficient of about -5.0 × 10 ^-6 /℃~10.0×10 ^-6 / ℃ As a result, when the heating resistor layer 3 is heated, the glaze layer 2 is hardly deformed by being affected by the heat. As a result, the heating resistor layer 3 is also hardly deformed. Therefore, since the crystallinity of the polycrystalline silicon is easily improved even when the heating resistor layer 3 is hardly deformed, it is possible to contribute to the improvement of the operating characteristics of the thermal head 10 from this viewpoint.

  In the present embodiment, since the glaze layer 2 is formed so as to include a crystallized glass that hardly diffuses impurities when heated as described above, crystallization that hardly diffuses impurities when heated is performed. It is possible to suppress the diffusion of impurities from the glaze layer 2 to the heating resistor layer 3 by utilizing the material characteristics of glass. In this case, when using the intermediate layer described in the above “Background Art” section, that is, since the glaze layer is formed so as to include amorphous glass that easily diffuses impurities when heated, the glaze is formed. Unlike the case where it is necessary to provide an intermediate layer for suppressing the diffusion of impurities between the layer and the heating resistor layer, it is not necessary to provide an intermediate layer between the glaze layer 2 and the heating resistor layer 3. The structure of the heat generating portion 10A is simplified by the amount that it is not necessary to provide the intermediate layer. Therefore, the configuration of the thermal head 10 can be simplified as much as possible in suppressing the diffusion of impurities from the glaze layer 2 to the heating resistor layer 3.

  In the present embodiment, the heating resistor layer 3 is heated at a temperature of the heating resistor layer 3 (polycrystalline silicon deposition temperature) to 1100 ° C. The temperature at which 3 is heated is made suitable. Therefore, as described above, excessive thermal influence (for example, deformation and generation of cracks) on the glaze layer 2 due to the heat treatment is suppressed, and impurities from the glaze layer 2 to the heating resistor layer 3 are suppressed. While suppressing the diffusion, the crystallinity of the heating resistor layer 3 can be remarkably improved by utilizing the heat treatment.

  In the present embodiment, since the heating resistor layer 3 is formed by depositing polycrystalline silicon using the CVD method, the heating resistor pair layer 3 is different from the case of using sputtering. As a result, the heat generation characteristics of the thermal head 10 can be controlled uniformly and the resistance characteristics of the heat generation resistor layer 3 fluctuate due to the influence of heat. As a result, the thermal head 10 can be applied to high-speed printing.

  In the present embodiment, since the heating resistor layer 3 is heated for a time of about 10 minutes to 10 hours, the heating time of the heating resistor layer 3 is optimized. Therefore, as described above, the crystallinity of the heating resistor layer 3 can be remarkably improved using heat treatment while ensuring the productivity of the thermal head 10.

  In the present embodiment, since the heating resistor layer 3 is heated and then the heating resistor layer 3 is cooled, the temperature of the heating resistor layer 3 is changed to the next step (the step of forming the electrode layer 4). ) Can be actively reduced to the extent that it does not adversely affect. In this case, in particular, by cooling the heating resistor layer 3 at a cooling rate of about 0.1 ° C./min to 5.0 ° C./min to optimize the cooling temperature of the heating resistor layer 3. As described above, the productivity of the thermal head 10 can be ensured while preventing the glaze 2 from cracking due to the cooling process.

In addition to the above, the thermal head 10 according to the present embodiment includes the glaze layer 2 configured to include crystallized glass. For example, the thermal head 10 is formed on the glaze layer 2 in the manufacturing process of the thermal head 10. By heating the heating resistor layer 3, as described above, the crystallinity of the polycrystalline silicon constituting the heating resistor layer 3 is remarkably improved. Specifically, the Raman spectrum of the heating resistor layer 3 is increased. The half width of the peak is 16 cm ⁻¹ or less. Therefore, it is possible to improve the operating characteristics represented by the SST characteristics and the pulse resistance characteristics as much as possible.

  In the present embodiment, as shown in FIG. 4, after the heating resistor layer 3 is formed, the heating resistor layer 3 is heated (post-heating). However, the present invention is not limited to this. Instead, for example, as shown in FIG. 5, the heating resistor layer 3 may be formed while heating the substrate 1 instead of the method of post-heating the heating resistor layer 3. FIG. 5 is a diagram for explaining a modification example relating to the method of manufacturing the thermal head. In this thermal head manufacturing method as a modified example, the substrate 1 as a base is prepared, and after the glaze layer 2 is formed on the substrate 1 (step S201), the substrate 1 is heated while the substrate 1 is heated. The heating resistor layer 3 is formed by depositing crystalline silicon (step S202). When forming the heating resistor layer 3, for example, a polycrystalline silicon film is formed using a CVD method, and the heating resistor layer 3 is formed while heating the substrate 1 at a temperature of 550 ° C. to 1100 ° C. Form. Subsequently, the heating resistor layer 3 is cooled (step S203). When the heating resistor layer 3 is cooled, for example, the heating resistor layer 3 is cooled at a cooling rate of about 0.1 ° C./min to 5.0 ° C./min. Finally, after the electrode layer 4 is formed on the heating resistor layer 3 so as to include the electrode layers 4A and 4B (step S204), the protective layer 5 is formed so as to cover the heating resistor layer 3 and the electrode layer 4 By forming (step S205), the heat generating portion 10A of the thermal head 10 is completed. The detailed process contents other than those described above with respect to the thermal head manufacturing method as a modified example are the same as the detailed process contents of the thermal head manufacturing method described with reference to FIG. 4 in the above embodiment, for example. is there. Also in this case, by forming the heating resistor layer 3 while heating the substrate 1, the same effect as in the case of the above embodiment in which the heating resistor layer 3 is post-heated can be obtained. The operating characteristics can be improved as much as possible.

  Next, specific examples of the present invention will be described.

  After manufacturing the thermal head using the thermal head manufacturing method described in the above embodiment (hereinafter referred to as “the thermal head manufacturing method of the present invention”), various characteristics of the thermal head were examined. The following results were obtained. When investigating various characteristics of a thermal head manufactured using the method for manufacturing a thermal head according to the present invention, in order to compare and evaluate the characteristics, an amorphous glass is used instead of crystallized glass. The same procedure as that of the thermal head manufacturing method of the present invention (except for the thermal head of the comparative example) except that the glaze layer was formed and the heating resistor layer was not heated (left in a temperature environment of 30 ° C.). A thermal head was manufactured using a manufacturing method), and various characteristics of the thermal head were also investigated.

First, when the crystallinity of the heating resistor layer (polycrystalline silicon) was examined using Raman spectroscopy, the result shown in FIG. 6 was obtained. FIG. 6 shows the results of Raman spectroscopic analysis of polycrystalline silicon. The “horizontal axis” indicates the heating temperature (° C.), and the “vertical axis” indicates the full width at half maximum (FWHM (Full Width Half Maximum); cm ⁻¹ ). Show.

When a thermal head is manufactured using the method for manufacturing a thermal head of the present invention, a substrate (alumina; Al ₂ O ₃ ) / glaze layer (crystallized glass on which a spodumene solid solution is deposited) / a heating resistor layer (multiple layers) A heating part was formed so as to have a structure of crystalline silicon; Poly-Si) / electrode layer (aluminum; Al) / protective layer (boron-phosphorus compound; BP). In particular, with respect to the heating resistor layer, after forming the heating resistor layer on the heat storage layer by depositing polycrystalline silicon at a deposition temperature of 550 ° C. using the CVD method, four temperatures (600 The heating resistor layer was heated at 30 ° C., 650 ° C., 700 ° C., and 750 ° C. for 30 minutes, and then the heating resistor layer was cooled at a cooling rate of 1.0 ° C./min. The “black square (■)” shown in FIG. 6 represents the analysis result relating to the present invention (glaze layer = crystallized glass, heat treatment; heating temperature = 600 ° C., 650 ° C., 700 ° C., 750 ° C.) “Black circles (●)” represent the analysis results for the comparative example (glaze layer = amorphous glass, no heat treatment).

  As a correlation between the crystallinity of polycrystalline silicon and the result of Raman spectroscopic analysis, it is generally known that the half-value width of a Raman spectrum peak decreases as the crystallinity of polycrystalline silicon increases. From this, it is possible to evaluate the crystallinity of polycrystalline silicon based on the half-value width of the Raman spectrum peak.

In this regard, as can be seen from the results shown in FIG. 6, when the half width was compared between the present invention (■) and the comparative example (●), the half width was smaller in the present invention than in the comparative example. It was. Specifically, the half width is 17.10 cm ⁻¹ in the comparative example (glaze layer = amorphous glass, no heat treatment), and the present invention (glaze layer = crystallized glass, heat treatment present; heating temperature = 600 ° C., 650 ° C., 700 ° C., and 750 ° C.), respectively, were 16.00 cm ⁻¹ , 14.50 cm ⁻¹ , 12.00 cm ⁻¹ , and 9.99 cm ⁻¹ . Therefore, in the method of manufacturing a thermal head according to the present invention, the heating resistor layer is heated in a state where the glaze layer is formed so as to include crystallized glass, thereby improving the crystallinity of the heating resistor layer. Is confirmed to be possible. In particular, in the method for manufacturing a thermal head according to the present invention, the half-value width decreases as the heating temperature increases. Therefore, it is confirmed that the crystallinity of the heating resistor layer can be further improved as the heating temperature is increased. It was. By the time of confirmation, as for the thermal head manufactured by using the thermal head manufacturing method of the present invention, no thermal influence (for example, deformation or generation of cracks) was observed on the glaze layer as long as it was visually confirmed. .

  Although not specifically described with reference to data, the heating temperature in the method of manufacturing the thermal head of the present invention is set to other than the above four temperatures (600 ° C., 650 ° C., 700 ° C., 750 ° C.). When the temperature was changed, when the heating temperature was set to 550 ° C. to 1100 ° C., the same analysis result as that obtained when the heating temperature was set to be the above-described four temperatures was obtained. Similarly, although not specifically described with reference to the data, the heating time of the heating resistor layer is changed to be other than 30 minutes as described above, and the cooling time of the heating resistor layer is changed to 1.0 as described above. When the temperature was changed to other than ° C./min, the heating time was set to 10 minutes to 10 hours and the cooling rate was set to 0.1 ° C./min to 5.0 ° C./min. In the case, as described above, the same analysis results as those obtained when the heating time was set to 30 minutes and the cooling time was set to 1.0 ° C./minute were obtained. From these facts, in the thermal head manufacturing method of the present invention, when the heating resistor layer is formed by forming a polycrystalline silicon film at a film forming temperature of 550 ° C. using the CVD method, After heating the heating resistor layer at a temperature of 1100 ° C. for 10 minutes to 10 hours, the heating resistor layer is cooled at a cooling rate of 0.1 ° C./min to 5.0 ° C./min. Thus, it was confirmed that the crystallinity of the heating resistor layer can be improved.

Subsequently, when the operating characteristics of the thermal head were examined, the results shown in FIG. 7 were obtained. FIG. 7 shows the SST characteristics of the thermal head. The “horizontal axis” shows the applied power (W / dot) per dot of the heating resistor layer, and the “vertical axis” shows the resistance change rate (%). ing. As this SST characteristic, the change in the resistance change rate when the applied power was applied to the heating resistor layer while being increased stepwise was tracked. “7A”, “7B”, and “7C” shown in FIG. 7 represent characteristic results relating to the series of thermal heads of the present invention shown in FIG. 6, that is, “7A” is heating temperature = 600 ° C., half-value width. = 16.00 cm ⁻¹ , “7B” represents heating temperature = 700 ° C., half width = 12.00 cm ⁻¹ , and “7C” represents heating temperature = 750 ° C., half width = 9.99 cm ⁻¹ , respectively. Further, “7D” shown in FIG. 7 represents a characteristic result regarding the thermal head of the comparative example shown in FIG. 6 (left in a temperature environment of 30 ° C., half-value width = 17.10 cm ⁻¹ ).

  As can be seen from the results shown in FIG. 7, when the change in the resistance change rate of the heating resistor layer was traced while increasing the applied power, the resistance change rate was determined according to the present invention (7A to 7C) and the comparative example (7D). In any of the cases, although it was almost constant in the initial state, it was greatly changed in the negative direction in the applied power = 0.6 W / dot neighborhood. However, as the SST characteristic of the thermal head, when the applied power when the resistance change rate reaches ± 5% is compared between the present invention and the comparative example, the resistance change rate is ± 5% (here, −5%). %) Applied power is 0.62 W / dot, 0.70 W / dot, 0.76 W / dot in the present invention (7A, 7B, 7C), respectively, and 0.59 W / dot in the comparative example, It became larger in this invention than the comparative example. This confirms that the thermal head manufactured using the method for manufacturing a thermal head according to the present invention can improve the SST characteristics because the resistance characteristics of the heating resistor layer are less likely to change. It was. In this case, particularly when comparing the applied power when the rate of change in resistance reaches ± 5% between the present inventions (7A to 7C), the applied power increases in the order of 7A, 7B, and 7C. As the heating temperature of the heating resistor layer increased, the heating resistor layer increased. From this, it was confirmed that the SST characteristics can be improved as the heating temperature is increased in the method for manufacturing the thermal head of the present invention.

  The present invention has been described with reference to the embodiments and examples. However, the present invention is not limited to the modes described in the above embodiments and examples, and various modifications can be made. Specifically, for example, in the above-described embodiment and example, in order to prevent an excessive thermal influence (for example, generation of deformation or cracks) on the glaze layer when the heating resistor layer is heated. The upper limit value of the temperature for heating the heating resistor layer is defined as 1100 ° C., but is not necessarily limited thereto. For example, when the heating resistor layer is heated, an excessive thermal influence is exerted on the glaze layer. As long as it does not reach, the upper limit of the temperature which heats a heating resistor layer may be made higher than 1100 degreeC depending on the heat resistance of the glaze layer. Even in this case, the same effects as those of the above-described embodiment and examples can be obtained. However, in the case where the upper limit value of the temperature for heating the heating resistor layer is set higher than 1100 ° C., not only the glaze layer but also other components constituting the thermal head are not excessively affected by heat. Need to be careful. In addition, the deformation | transformation aspect which makes the temperature which heats the above-mentioned heating resistor layer higher than 1100 degreeC is a board | substrate in the case of forming a heating resistor layer, heating a board | substrate as demonstrated as a modification in the said embodiment. The same applies to the heating temperature.

  The thermal head and the manufacturing method thereof according to the present invention can be applied to a thermal head including a glaze layer for storing heat generated in the heating resistor layer and a manufacturing method thereof.

It is a figure showing the external appearance structure (side surface structure seen from the Y-axis direction) of the thermal head which concerns on one embodiment of this invention. It is sectional drawing which expands and represents the cross-sectional structure (cross-sectional structure parallel to a XZ plane) of the heat generating part shown in FIG. FIG. 2 is an enlarged plan view illustrating a planar configuration (a planar configuration viewed from the Z-axis direction) of the heat generating unit illustrated in FIG. 1. It is a flowchart for demonstrating the flow of the manufacturing method of the thermal head which concerns on one embodiment of this invention. It is a flowchart for demonstrating the modification regarding the manufacturing method of the thermal head which concerns on one embodiment of this invention. It is a figure showing the Raman spectroscopic analysis result of a polycrystalline silicon. It is a figure showing the SST characteristic of a thermal head.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... Glaze layer, 3 ... Heat generating resistor layer, 4 (4A, 4B) ... Electrode layer, 5 ... Protective layer, 10 ... Thermal head, 10A ... Heat generating part, 10B ... Drive part, 11 ... Heat sink , 12 ... printed circuit board, 13 ... driver IC, 14 ... connector, 15 ... IC resin film, 16 ... IC cover, 17 ... adhesive, G ... gap.

Claims (12)

A heating resistor layer composed of polycrystalline silicon and having a Raman spectrum peak half-width of 16 cm ⁻¹ or less;
A thermal head comprising: a heat storage layer that is adjacent to the heating resistor layer and includes crystallized glass. 2. The thermal crystal according to claim 1, wherein the crystallized glass has a thermal expansion coefficient within a range of −5.0 × 10 ⁻⁶ / ° C. to 10.0 × 10 ⁻⁶ / ° C. head. The crystallized glass is composed of spodumene solid solution (LiAlSi ₂ O ₆ ), eucryptite solid solution (LiAlSiO ₄ ), petalite solid solution (LiAlSi ₄ O ₁₀ ), β-quartz solid solution (SiO ₂ ), and cordierite solid solution (2MgO · 2Al _2). The thermal head according to claim 1, wherein at least one crystal phase of a group including O ₃ .5SiO ₂ ) is precipitated. 4. The thermal head according to claim 1, wherein a half-value width of a Raman spectrum peak of the heating resistor layer is 12 cm ⁻¹ or less. 5. A first step of forming a heat storage layer to include crystallized glass;
A second step of forming a heating resistor layer on the heat storage layer;
And a third step of heating the heating resistor layer. In the first step,
Silicon oxide (SiO ₂ ) in the range of 45 wt% to 65 wt%;
Aluminum oxide (Al ₂ O ₃ ) in the range of 10 wt% to 30 wt%;
Lithium oxide (Li ₂ O) in the range of 3 wt% to 10 wt%;
Magnesium oxide (MgO) in the range of 0 wt% to 10 wt%,
6. The method for producing a thermal head according to claim 5, wherein the crystallized glass is produced by mixing zinc oxide (ZnO) in the range of 0 wt% or more and 10 wt% or less in a powder state. . In the second step, the heating resistor layer is formed by depositing polycrystalline silicon,
7. The thermal head according to claim 5, wherein, in the third step, the heating resistor layer is heated at a temperature in a range of not less than a film formation temperature of polycrystalline silicon and not more than 1100 ° C. 8. Production method. The method of manufacturing a thermal head according to claim 7, wherein in the second step, a polycrystalline silicon film is formed using a CVD (Chemical Vapor Deposition) method. A first step of forming a heat storage layer on the substrate so as to include crystallized glass;
And a second step of forming a heating resistor layer on the heat storage layer while heating the substrate. In the first step,
Silicon oxide (SiO ₂ ) in the range of 45 wt% to 65 wt%,
Aluminum oxide (Al ₂ O ₃ ) in the range of 10 wt% to 30 wt%;
Lithium oxide (Li ₂ O) in the range of 3 wt% to 10 wt%;
Magnesium oxide (MgO) in the range of 0 wt% to 10 wt%,
The method for producing a thermal head according to claim 9, wherein the crystallized glass is produced by mixing zinc oxide (ZnO) in the range of 0 wt% or more and 10 wt% or less in a powder state. . In the second step, the heating resistor layer is formed by forming a polycrystalline silicon film, and the substrate is heated at a temperature within a range of 550 ° C to 1100 ° C. The manufacturing method of the thermal head of Claim 9 or Claim 10. The thermal head manufacturing method according to claim 11, wherein, in the second step, a polycrystalline silicon film is formed using a CVD (Chemical Vapor Deposition) method.

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