JPS63146401A - Thin film heating resistor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a thin film heating resistor used in thin film planar heaters, thin film thermal heads, etc. that utilize Joule heat.

2. Description of the Related Art Thin film heating resistors are generally used in thin film thermal heads, thin film planar heaters, etc. that utilize Joule heat, but this specification will mainly discuss thin film thermal heads.

Now, a thermal head used for thermal print recording is provided with a plurality of heating resistors and electrodes for supplying power to the thermal resistors on an insulating substrate, and supplies power to each heating resistor. As a result, Joule heat is generated, and printing is thereby performed.

As the heat generating resistor used for these, thin film heat generating resistors are excellent in that they have good thermal responsiveness, can provide high resolution, have high reliability, and have low power consumption.

As a conventional thin film heating resistor, for example,
As stated in Japanese Patent No. 143841, Ta-5i alloy and the like have excellent heat resistance. However, in order to achieve high-speed thermal print recording using modern thermal heads, it is necessary to record using short print pulses of several milliseconds, and to do this, a large amount of power is applied to the thin-film heating resistor. It is necessary to generate a temperature of 400°C or more.

In addition, as power increases, the current inevitably increases unless the resistance value of the thin film heating resistor is increased, resulting in the following two problems. One is that the resistance value of the electrode that supplies power to the thin-film heating resistor cannot be ignored compared to the resistance value of the thin-film heating resistor, so the amount of heat generated by each thin-film heating resistor is This causes a difference in density in the recorded pattern, and especially when increasing the resolution, power consumption in the electrodes becomes a problem. In order to avoid this, it is conceivable to make the electrode thickness extremely large, but this would cause a major structural inconvenience. Another problem arises that the current capacity of a drive system such as a heating power supply switching circuit must be increased.

From the above points, a thin film heating resistor must have two minimum requirements: high temperature stability and the ability to realize a high resistance value. Considering the Ta-3i alloy from these points, in the composition range where the heat resistance is stable, the Ta-3i alloy has
The specific resistance is as small as about 200 to 250 μΩ-1, and therefore a large resistance value, for example, a resistance value of 1000Ω (
In order to obtain a resistance value higher than this (according to recent technology trends), the film thickness must be approximately 50 mm, with L/W = 2 (L is the length of the heating element and W is the width). It is thin and difficult to control during manufacturing, and when the film thickness reaches this level, film reproducibility may not be obtained due to thin film size effects such as surface scattering of conductive carriers, and the film quality may become unstable. Become. In order to avoid this, it is possible to increase the resistance value by increasing the thickness of the Ta-3i alloy, forming a pattern in a meandering shape, etc., and increasing the length, but when increasing the resolution, This method is manufacturing efficient. Also, Ta
The -3t alloy still does not have sufficient heat resistance during short pulse width driving, and therefore the Ta-3i alloy is not sufficient in terms of the high speed and high heat resistance required for thermal heads.

In order to solve the above problems, a thin film heating resistor with high heat resistance and high specific resistance is required. If a heating resistor is used, it is possible to satisfy both high heat resistance and high specific resistance with good controllability, but the following problem exists.

Tll Oxidation resistance (2) Variation in sheet resistance during manufacturing process (1)
), for example, a thin film heating resistor made of titanium carbide and silicon carbide (hereinafter abbreviated as TiC-3iC) is usually formed by sputtering using a sintered body of TiC and SiC as a target. At this time, due to the dissociation phenomenon caused by the high energy of incident ions during sputtering, the composition of the thin film formed is not necessarily a mixture of TiC and SiC with a stoichiometric composition (in addition, the composition of the thin film formed by sputtering is Generally, it has properties such as being in an amorphous state and easily containing gas, and due to these properties, it does not have sufficient oxidation resistance.Normally, a thermal head has a thin film heating resistor on which it prevents contact abrasion when printing on paper. , and to form a protective layer to prevent oxidation, oxygen is blocked, and TiC-3iC has extremely good heat resistance.

However, when there are pinholes or other defects in the protective layer, the thin film heating resistor is oxidized through the pinholes, resulting in a significant reduction in service life.

In addition, to solve the problem (2), specifically, as mentioned above, an electrode for power supply is formed on the thin film heating resistor, but in this case, this electrode layer and the thin film heating resistor A reaction layer is formed at the interface, and this reaction layer is scraped away during the patterning process, so the sheet resistance when forming the thin film heating resistor and the finished resistance value after patterning.

There were problems such as not being able to obtain good reproducibility in the sheet resistance calculated from the shape.

Problems to be Solved by the Invention As mentioned above, the Ta-3i alloy, which is the thin film heating resistor material of the conventional thermal head, still has insufficient characteristics to increase the speed and heat resistance of the thermal head. F!, consisting of transition metals, carbon, and silicon, does not contain! The membrane heating resistor is
The dependence on the formation temperature is small, so it can be formed with good controllability, and it can be used for high speed and high heat resistance.
fJ! When there is a defect such as a pinhole in i, there are problems such as oxidation and significant deterioration of the service life, as well as a failure to obtain good reproducibility of sheet resistance due to variations in the manufacturing process.

From this point of view, the present invention meets the necessary conditions for increasing the speed and heat resistance of a thermal head, namely, high resistance value, therefore high specific resistance, excellent high temperature stability, high heat resistance, and oxidation resistance. The main purpose of this invention is to provide a thin film heating resistor that is rich in properties and has good reproducibility during production.

Means for Solving the Problems In order to solve the above problems, the present invention provides a thin film heating resistor with a two-layer structure, the lower layer being a transition metal.

Select a material made of carbon or silicon, especially one made of titanium carbide and silicon carbide, with the upper layer being silicon or silicon oxide.

It is made of either silicon carbide or silicon nitride, especially silicon or silicon oxide.

Effect Material N (hereinafter abbreviated as TiC-3iC), which is made of titanium carbide and silicon carbide as the lower layer in the above-mentioned structure, has low dependence on the formation temperature (low-temperature formation is possible), can be formed with good controllability, and has excellent high-temperature stability. , heat resistance is also good. However, Ho! ! If the layer has defects such as pinholes, the life of the layer will be significantly deteriorated due to oxidation, and the layer that reacts with the electrode may be etched away during pattern formation, or the TiC-3iC itself may be etched by the electrode etching solution. There was a problem that good reproducibility of sheet resistance could not be obtained due to For this reason, TiC-3
Silicon or silicon oxide is formed to an appropriate thickness as an upper layer on the iC. At this time, silicon has an extremely strong natural oxide film on its surface (not to mention silicon oxide), so its anti-oxidation effect protects the underlying layer, dramatically improving oxidation resistance and Since the upper layer of silicon and silicon oxide serve as a buffer layer for the etching solution, the lower layer of TiC-3iC mentioned above is not etched and extremely good sheet resistance reproducibility can be obtained. In addition, even with a two-layer structure, only TiC-3iC (
- As in the case of the 3-layer method, the dependence on the forming temperature is small and the controllability during forming is good.

As described above, a two-layer structure thin film heating resistor having a material layer consisting of TiC-3iC in the lower layer and silicon or silicon oxide in the upper layer can be produced extremely easily and stably, has good reproducibility, and has high resistance. Because it has excellent high temperature stability, oxidation resistance, and high thermal shock resistance, it can be used, for example, to easily produce 'i? It can match the high speed and high heat resistance of the 1llI type thermal head.

Example (Example 1) Figure 1 (al) shows the basic structure of the thin film heating resistor of the present invention.
A two-layer thin film heating resistor made of silicon (hereinafter abbreviated as Si) was used as the upper material layer.

Now, in FIG. 1, a thin film with a two-layer structure consisting of a lower material layer 2 made of TiC-3iC and an upper material layer 3 made of Si is formed on an electrically insulating substrate 1 by a thin film forming technique such as sputtering. A heating resistor 4 was formed. Figure 2 shows the change in sheet resistance when this thin film heating resistor 4 was heat treated in the atmosphere for 1 hour. In this figure, the horizontal axis is the heat treatment temperature, and the vertical axis is the sheet resistance change rate (initial value (change from)

Moreover, the song &I5 is based on the lower material layer TiC-3iC of the present invention.
As an example of sheet resistance change characteristics of a thin film heating resistor 4 having a two-layer structure consisting of a top layer material JiSi3 and an upper layer material JiSi3,
00 people and the sheet resistance is 1000Ω/mouth. Also, for reference, curve 6 is TiC-
3iC only (no upper layer Si) (sheet resistance 1000Ω
From the comparison of 0 songs vA5 and 6 showing the sheet resistance change characteristics of By doing so, the oxidation resistance is dramatically improved, and the 800
It is clear that there is no oxidation and the change in sheet resistance is small even at ℃. This is because the oxide film formed on the surface of the upper material layer 313 is strong and prevents oxygen from entering. As described above, the two-layer structure thin film heating resistor 4 of the present invention has oxidation resistance up to about 800°C and does not deteriorate even in an oxidizing atmosphere. It can be used for thin film surface heaters, etc.

(Example 2) FIG. 3 shows an example of application of the thin film heating resistor of the present invention to a thin film type thermal head. Using thin film forming technology such as sputtering, the lower layer material 1iT
A thin film heating resistor 4 having a two-layer structure consisting of IC-3iC2 and an upper material layer Si3 is formed, and the thin film heating resistor 4 is formed on this.
After forming the electrode 7 for energizing, a pattern is formed using photolithography technology, and an insulating material,
A protective layer 8 made of a semiconductor or the like (the protective layer 8 is usually present to prevent oxidation of the thin film heating resistor and prevent contact abrasion during printing on paper) is formed.

As shown in FIG. 4, the sheet resistance of the finished thin film heating resistor 4 can be calculated from the length of the heating element when the thin film heating resistor 4 is patterned, the heating element width W, and the resistance value R.
1, Pscall-R*(W/L), and the relationship between this and the sheet resistance P3 during film formation of the thin film heating resistor 4 is shown in FIG. 5 depending on the presence or absence of the upper material layer Si3. In the same figure, the specific resistance of the lower layer TiC, -5iC is 2mΩ-
Case (2) is shown, the horizontal axis is Ps, and the vertical axis is Pscal.
represents.

Line 8 is when there is no upper layer Si3, and line 9 is when there is upper layer Si3 (S 1JE 100 people).

If there is no JiSi3 above line 8, Pscal is relatively large compared to Ps, and Ps-1 and 4 deviate from the straight line by about Ω/mouth, and Pscal increases rapidly. In contrast, line 9 has almost the same Ps and Ps(aj) and has linearity to Ps-2 up to about Ω/mouth. Due to problems such as the reaction layer formed at the interface of the heating resistor being scraped off by etching during the pattern formation process, and the thin film heating resistor itself being etched by the etching solution of the electrode 7, etc. In addition to impairing the reproducibility of
This results in a rapid increase in PScal because the size effect (resistance due to surface scattering is added) near 00 occurs. In contrast, when there is an upper layer Si3,
The area removed by etching is the upper N Si
3, the lower layer TiC-3iC2 is not subject to any restrictions. Therefore, the lower layer TiC-3iC2 itself has a film thickness of about 100 nm which causes a size effect during film formation.
Ps-Pscaj has good linearity up to about Ω/mouth in s-2, and the values of P S and P 5cajl are almost the same. In addition, from the viewpoint of specific resistance, the upper layer S
Regarding i3, at least up to the St thickness of 100 as in this embodiment, it is considered to be almost the same as the case where there is no upper layer Si3. The regulation of the thickness of the upper layer Si3 differs depending on the film formation process temperature. For example, if the formation temperature of the electrode 7 is raised, the electrode 7 will diffuse into the upper layer Si3, and the upper layer Si3 will be
Since the contact resistance caused by Si3 decreases, it is not necessarily necessary to reduce the contact resistance to 100 Å or less, which causes the general tunneling phenomenon. It is thought that the thickness of the board is limited to about 200 people at most.

As described above, the thin film heating resistor with the two-layer structure consisting of the lower TiC-3iC layer and the upper FiSi layer can reduce process fluctuations, thus achieving good reproducibility and increasing the controllable sheet resistance range. , it is extremely easy to increase the resistance.

Next, the thin film heat generating resistor of the present invention was constructed to have the structure shown in FIG. 3, and its thermal shock resistance was examined. FIG. 6 shows the results of a continuous pulse application test. The test conditions are: 1 during the applied pulse
, 05sec, circumference M20 m5ec, applied power density 6
Continuous pulses were applied at 4 W/mm2. In the figure, the horizontal axis represents the number of pulse applications, and the vertical axis represents the resistance change rate (the number of pulses at which the resistance change rate exceeds +5% is defined as the life span).
Line IO is a conventional thin film heating resistor Ta-3+
Gold alloy formed at 500°C), line 11.12 are both the upper layer 1si (thickness 100 mm) and lower layer TiC-3 of the present invention.
iC's two-layer structure thin film heating resistor, each at 350℃ and 6
It was formed at 50°C.

From lines 10 to 12, it can be seen that the thin film heating resistor of the present invention has significantly improved heat resistance compared to the conventional Ta-Si alloy, and despite the difference in forming temperature of 350 to 650°C. First, since there is no difference in characteristics, it is possible to form at a low temperature, and even if the forming temperature is controlled over a wide range, the reproducibility of the resistance value is good. Furthermore, those without the protective layer 8 in FIG. 3 had almost the same characteristics as lines 11 and 12, and no deterioration due to oxidation occurred. Therefore, the thin film heating resistor in the present invention has excellent controllability.

It is possible to easily increase the resistance with good reproducibility, and it also has excellent heat resistance and oxidation resistance. Thin-film thermal heads using this are extremely reliable and can easily be increased in speed and heat resistance. I can figure it out. In addition to this, as long as there is no problem with abrasion,
It is possible to make the protective layer 8 thinner, and the protection layer 8 can be made thinner.
If there is a defect such as a pinhole in the upper layer Si, water may enter through the defect and electrolytic corrosion may occur.
3 also has a preventive effect.

In addition, when using the thin film heating resistor of the present invention, for example, the electrode 7 and the electrode 1 [N8 are usually formed using a thin film forming technique such as sputtering (non-oxidizing atmosphere technique such as vacuum). However, these can be formed by printing and baking techniques, such as printing and baking 1 on the pole 7 and printing and baking glass on the protective layer 8, which requires baking in the air at about 800 degrees Celsius. Even when applied, the degree of freedom in the process is greatly increased, such as making it possible to create a thermal head with high reliability.

As described above, the thin film heating resistor with a two-layer structure consisting of the lower material layer TiC-8rCs and the upper material layer Si has a small dependence on the formation temperature and is easy to control.

High resistance can be easily achieved with good reproducibility, and it is also heat resistant.

It has excellent high-temperature stability and oxidation resistance, and can easily produce thin-film thermal heads, thin-film heaters, etc. with high reliability and performance.

In this Example 1.2, TiC-3i is used as the lower material layer.
C was used, but other transition metals were used.

Even when a mixture of carbon and silicon was used, similar effects were obtained because these mixtures have a small dependence on the formation temperature, can be made high in resistance, and have high heat resistance. In addition, although Si was used for the lower material layer, silicon oxide has a strong oxidation prevention effect, and silicon carbide, silicon nitride, etc. can also be used to prevent oxidation of the natural oxide film that exists on the surface layer. The effects were similar.

Effects of the Invention As described above, the present invention has a material layer comprising a transition metal, carbon, and silicon as the lower layer, and silicon as the upper layer.

It is a thin film heating resistor with a two-layer structure having a material layer made of either silicon oxide, silicon carbide, or silicon nitride.It has low dependence on formation temperature, and can easily be made high in resistance with good controllability and reproducibility.
It has excellent heat resistance, high-temperature stability, and oxidation resistance. For example, thin-film thermal heads using it can easily support higher speeds, higher heat resistance, and improved reliability, and have great industrial value. is very high.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the basic configuration of the thin film heating resistor of the present invention, Fig. 2 is a characteristic diagram showing the oxidation resistance of the same resistor, and Fig. 3 is a diagram showing an example of the thin film heating resistor of the present invention. A cross-sectional view of the structure of the thin-film thermal head. Figure 4 is an explanatory diagram to explain the process variations in sheet resistance of the head. Figure 5 is a characteristic diagram showing process variations in sheet resistance. Figure 6 is the thermal shock resistance. FIG. 2... Lower material layer, 3... Upper material layer, 4... Thin film heating resistor. Name of agent: Patent attorney Toshio Nakao (1 person) Figure 1 Figure 2 Atmosphere Kamioso et al. 4 Soto (C) Figure 3 Figure 4 Figure 5)

Claims (4)

[Claims] (1) A material layer whose lower layer is made of transition metal, carbon, and silicon,
1. A thin film heating resistor, wherein the upper layer is made of a material layer made of silicon, silicon oxide, silicon carbide, or silicon nitride. (2) The thin film heating resistor according to claim (1), wherein the transition metal in the lower layer is titanium. (3) The thin film heating resistor according to claim (1), wherein the lower material layer made of transition metal, carbon, and silicon is a mixture of titanium carbide and silicon carbide. (4) Claim No. 1 having a two-layer structure in which the lower layer is a material layer made of a mixture of titanium carbide and silicon carbide, and the upper layer is a material layer made of either silicon or silicon oxide.
) The thin film heating resistor described in item 1.