JP4051228B2 - Recording head manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a recording head such as a thermal head or an ink jet head incorporated as a printer mechanism such as a facsimile or a video printer.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a recording head such as a thermal head or an ink jet head has been used as a recording device incorporated as a printer mechanism such as a facsimile or a video printer.
[0003]
As such a conventional recording head, a thermal head as shown in FIG. 8 is known, and this thermal head has an upper surface of a long silicon substrate 11 on which an insulating layer 12 made of silicon oxide is deposited. In addition, a large number of heating resistors 13 are arranged along the long side, and a pair of electrodes is attached to each of the heating resistors 13. For example, when printing is performed using an ink ribbon In addition, while the ink ribbon and the recording paper are superposed on each other and conveyed onto the heating resistor 13 by a platen roller or the like, the heating resistor 13 is selectively heated individually based on an external print signal, and The generated heat is conducted to the ink ribbon on the heating resistor 13 to heat and melt the ink on the ink ribbon, and this is pressed and transferred to the recording paper to form a thermal head. Functional.
[0004]
Such a thermal head employs a “multiple picking” method for obtaining a plurality of thermal heads from one single crystal silicon wafer.
An insulating layer made of silicon oxide is formed on the upper surface of a single crystal silicon wafer divided into a plurality of long sections by a thermal oxidation method,
Next, on each of the sections, a number of heating resistors are attached and arranged along their long sides, and electrodes (not shown) electrically connected to the heating resistors are attached,
Finally, a plurality of thermal heads can be obtained simultaneously by dividing the single crystal silicon wafer into each section by dicing using a diamond blade or the like.
[0005]
In the above thermal head, in order to make the width of the silicon substrate as small as possible, or in order to transfer the ink of the ink ribbon melted by the heat of the heating resistor to the recording paper during the recording operation, the heating resistor is used. The body 13 is arranged as close as possible to the long side of the silicon substrate 11.
[0006]
[Problems to be solved by the invention]
However, since the single crystal silicon wafer used in manufacturing the above-described conventional thermal head has a relatively brittle property, when the single crystal silicon wafer is divided into sections, a diamond blade or the like is used. Chipping may occur at the corners of the resulting thermal head due to the pressing force applied to the single crystal silicon wafer. Therefore, such chipping reaches the heat generating resistor 13 arranged in the vicinity of the long side of the silicon substrate 11, and a part of the heat generating resistor 13 is chipped to cause a printing defect, resulting in a decrease in yield of the thermal head. Had.
[0007]
In addition, the single crystal silicon wafer used in the above-described conventional thermal head manufacturing method has a linear expansion coefficient significantly different from that of silicon oxide constituting the insulating layer 12 formed on the upper surface thereof. Due to the heat applied when the insulating layer 12 is formed, a large thermal stress is accumulated inside the single crystal silicon wafer. For this reason, when the single crystal silicon wafer is divided into elongated shapes, the thermal stress accumulated inside the single crystal silicon wafer is released in large quantities at a time, and the thermal head obtained by dividing the single crystal silicon wafer into a bow shape. It has the disadvantage that it is curved and causes distortion in the image formed on the recording paper using such a thermal head.
[0008]
The present invention has been devised in view of the above drawbacks, and its object is high yield, yet the production of the recording head capable of obtaining the recording heads capable of forming a clear printed on the recording paper It is to provide a method.
[0009]
[Means for Solving the Problems]
The method for manufacturing a recording head according to the present invention includes a step of forming an insulating layer on the upper surface of a single crystal silicon wafer divided into a plurality of elongated sections, and a plurality of sections along the long sides of each section. A step of attaching and arranging the heating resistors in a straight line by a thin film forming technique, a groove is formed by etching in an insulating layer located at a boundary portion between the adjacent sections, and silicon is exposed on a bottom surface of the groove. A step of making a corner formed between the bottom surface and the side surface of the groove into a curved surface, and dicing the single crystal silicon wafer at the bottom surface of the groove to divide each section to obtain a plurality of recording heads And a process .
[0010]
In the present manufacturing method, it is preferable that the long section of the long section is arranged substantially parallel to the <110> direction of the single crystal silicon wafer. In the present manufacturing method, the insulating layer is preferably formed by oxidizing the upper surface of the single crystal silicon wafer by a thermal oxidation method. In the present manufacturing method, the radius of curvature at the corner is preferably set to 5.0 μm to 50.0 μm .
[0011]
In this manufacturing method, a step of forming a protective film covering at least the heating resistor and made of silicon nitride or silicon oxide by a thin film forming technique, and forming a concave portion at a position of the groove in the protective film, a photolithography technique And a step of forming by an etching technique. In this manufacturing method, it is preferable that the width of the concave portion of the protective film is set wider than the width of the groove .
[0012]
According to the recording head manufacturing method of the present invention, the insulating layer is formed on the upper surface of the single crystal silicon wafer divided into a plurality of elongated sections, and the insulation located at the boundary between adjacent sections is formed. Since a groove is formed in the layer and silicon is exposed on the bottom surface of the groove, a part of the thermal stress accumulated in the single crystal silicon wafer is appropriately released from the boundary portion. The amount of thermal stress in the single crystal silicon wafer that is released at one time during the cutting can be reduced. Therefore, the degree of curvature of the recording head obtained by dicing the single crystal silicon wafer can be reduced, the linearity of the arrangement of the heating resistors can be maintained well, and a good image with little distortion with respect to the recording paper Can be obtained.
[0013]
In addition, in this case, since the single crystal silicon wafer is diced at the bottom surface of the groove where the accumulated amount of thermal stress is small, the problem that chipping occurs at the corner of the obtained recording head and the heating resistor is missing is effective. Therefore, the yield of the recording head can be improved.
[0014]
According to the recording head manufacturing method of the present invention, since the groove is formed at the boundary portion between adjacent sections, there is a step between the bottom surface of the groove and the upper surface of the insulating layer in the vicinity of the groove. Thus, when dicing a single crystal silicon wafer, if an excessively large pressing force is applied to the single crystal silicon wafer and chipping occurs in the recording head, such chipping may occur on the top surface of the insulating layer. The heating resistor is hardly chipped and the yield of the recording head can be further increased.
[0015]
Furthermore, according to the recording head manufacturing method of the present invention, the long sides of the plurality of elongated sections formed on the upper surface of the single crystal silicon wafer are in the <110> direction where the mechanical strength of the single crystal silicon wafer is high. By arranging so as to be substantially parallel to the recording head, the frequency of occurrence of chipping in the recording head obtained from the single crystal silicon wafer is further reduced, and the yield of the recording head is remarkably improved, and the recording head is generated. The amount of warpage is further reduced, and the image formed on the recording paper can be made clearer.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a plan view of a thermal head manufactured by using the recording head manufacturing method of the present invention, and FIG. 2 is a cross-sectional view of the thermal head of FIG. 1. The thermal head is formed on a silicon substrate 1. A large number of heating resistors 3 are arranged on the upper surface of the insulating layer 2.
[0017]
The silicon substrate 1 is formed in a long shape by dividing a later-described single crystal silicon wafer 1a formed of single crystal silicon, the surface orientation of the upper surface is the (100) plane, and the long side is <110. >, The insulating layer 2, a large number of heating resistors 3, a pair of electrodes (not shown), and the like are formed on the upper surface and function as a support base material for supporting them.
[0018]
The insulating layer 2 provided on the silicon substrate 1 electrically insulates the single crystal silicon forming the silicon substrate 1 from the heating resistor 3 and the like, and also generates heat generated by the heating resistor 3 therein. It is for accumulating a part and improving the thermal responsiveness of the heating resistor 3, and is formed to a thickness of 1.0 μm to 20.0 μm by an inorganic material mainly composed of silicon oxide.
[0019]
On the upper surface of the insulating layer 2, a groove 2 a is formed in a ring shape in a region along the outer edge of the silicon substrate 1, and the silicon substrate 1 is exposed on the bottom surface of the groove 2 a.
[0020]
Further, a large number of heating resistors 3 provided on the upper surface of the insulating layer 2 are linearly deposited and arranged along the long side of the silicon substrate 1 with a density of, for example, 300 dpi (dot per inch). Since each is made of an electric resistance material such as TaSiO, TiSiO, TiCSiO, etc., when a predetermined power is applied via a pair of electrodes connected to both ends, Joule heat is generated, Heat is generated at a predetermined temperature suitable for forming a print.
[0021]
Thus, in the thermal head described above, the ink ribbon and the recording paper are superposed on the heating resistor 3 with a platen roller or the like, and the heating resistor 3 is connected to the heating resistor 3 via a pair of electrodes (not shown). Electric power is applied, and the heating resistors 3 are selectively heated individually based on an external print signal, and the generated heat is conducted to the ink ribbon on the heating resistor 3 so that the ink on the ink ribbon is discharged. It functions as a thermal head by heating and melting and pressing and transferring it onto a recording sheet.
[0022]
Next, a method for manufacturing a recording head according to an embodiment of the present invention will be described in detail with reference to FIGS.
First, as shown in FIG. 3A, the insulating layer 2 is formed on the upper surface of the single crystal silicon wafer 1a.
[0023]
First, the single crystal silicon wafer 1a employs a conventionally known chocolate ski method (pulling method) to obtain an ingot (lumps) made of single crystal silicon, which is sliced into a predetermined thickness and then polished on the surface. It is manufactured by.
[0024]
The single crystal silicon wafer 1a is divided into a plurality of long sections whose upper surfaces are formed by grooves 2a described later, and the long sides of these sections are substantially parallel to the <110> direction of the single crystal silicon wafer 1a. A large number of heating resistors 3, electrodes (not shown), and the like are formed in each of these sections.
[0025]
Further, the insulating layer 2 is formed to have a thickness of, for example, 1.0 μm to 20.0 μm by oxidizing the upper surface of the single crystal silicon wafer 1a by adopting a conventionally known thermal oxidation method, thin film formation technique, or the like. The At this time, a large amount of thermal stress due to a difference in linear expansion coefficient from silicon oxide forming the insulating layer 2 is applied to the inside of the single crystal silicon wafer 1a.
Next, as shown in FIGS. 3B and 4, the insulating layer 2 is processed into a predetermined pattern by employing a conventionally known photolithography technique and etching technique.
[0026]
The insulating layer 2 has a groove 2a formed along the boundary by etching the boundary between adjacent sections into a strip shape, and silicon is exposed on the bottom of the groove 2a. A part of the thermal stress accumulated in the single crystal silicon wafer 1a is moderately released from 2a.
[0027]
The groove 2a formed in the insulating layer 2 has a square cross section, and the width is set to 50 μm to 200 μm and the depth is set to 2.0 μm to 50 μm.
Next, as shown in FIG. 3C, the heating resistor 3 and a pair of electrodes (not shown) are deposited on the upper surface of the insulating layer 2.
[0028]
The heat generating resistors 3 are linearly attached and arranged along the long sides of each section. Such a heat generating resistor 3 and a pair of electrodes (not shown) are conventionally known thin film forming techniques. First, a predetermined pattern is formed in each section by sputtering, photolithography, etching, or the like.
(4) Finally, as shown in FIG. 3D, the single crystal silicon wafer 1a is diced on the bottom surface of the groove 2a.
[0029]
For this dicing, for example, a cutting device having a diamond blade supported in a rotatable manner or the like is preferably used, whereby the single crystal silicon wafer 1a is divided into sections and a plurality of thermal heads are obtained.
[0030]
According to the manufacturing method as described above, the insulating layer 2 is formed on the upper surface of the single crystal silicon wafer 1a divided into a plurality of elongated sections, and the insulation located at the boundary between adjacent sections is formed. Since the groove 2a is formed in the layer 2 and silicon is exposed at the bottom surface of the groove 2a, a part of the thermal stress accumulated in the single crystal silicon wafer is moderately released from the boundary portion. The amount of thermal stress inside the single crystal silicon wafer that is released at a time when the single crystal silicon wafer 1a is divided can be reduced. Therefore, the degree of curvature of the thermal head obtained by dicing the single crystal silicon wafer 1a can be reduced, and the linearity of the arrangement of the heating resistors 3 can be maintained well, and the distortion is excellent with respect to the recording paper. It is possible to obtain a thermal head that records a clear image.
[0031]
Moreover, in this case, since the single crystal silicon wafer 1a is diced at the bottom surface of the groove 2a where the accumulated amount of thermal stress is small, chipping occurs at the corners of the obtained thermal head and the heating resistor 3 is missing. Problems can be effectively prevented and the yield of the thermal head can be improved.
[0032]
Further, according to the above-described thermal head manufacturing method, since the groove 2a is formed at the boundary between adjacent sections, there is a step between the bottom surface of the groove 2a and the upper surface of the insulating layer 2 in the vicinity of the groove. Therefore, when the single crystal silicon wafer 1a is diced, if an excessively large pressing force is applied to the single crystal silicon wafer 1a, chipping may occur in the thermal head. The heating resistor 3 hardly reaches the upper surface of the insulating layer 2 and the heat generating resistor 3 is hardly chipped, and the yield of the thermal head can be further increased.
[0033]
Furthermore, according to the above-described thermal head manufacturing method, the long sides of the plurality of long sections formed on the upper surface of the single crystal silicon wafer are substantially the same with respect to the <110> direction where the mechanical strength is relatively high. Since they are arranged in parallel, the frequency of chipping in the thermal head obtained from the single crystal silicon wafer 1a is further reduced, the yield of the thermal head is dramatically improved, and the amount of warp generated in the thermal head is reduced. Further reduction is achieved, and the image formed on the recording paper can be made clearer.
[0034]
The present invention is not limited to the above-described embodiment, and various changes and improvements can be made without departing from the gist of the present invention.
[0035]
For example, in the above-described embodiment, the groove 2a is provided before the heating resistor 3 and a pair of electrodes (not shown) are attached in the respective sections. Instead, the groove 2a is shown in FIG. As described above, the groove 2a may be provided after the heating resistor 3 or a pair of electrodes (not shown) are attached in each section.
[0036]
In the above embodiment, the case where the recording head manufacturing method of the present invention is applied to a thermal head has been described. Alternatively, the manufacturing method of the present invention may be applied to an ink jet head. The same effect can be obtained. In the case of manufacturing an ink jet head, after obtaining a head substrate by the above-described manufacturing method, a nozzle member having a large number of ink discharge holes corresponding to the heating resistor 3 is provided on the head substrate with a predetermined gap therebetween. It is only necessary that the gap is formed and the gap is filled with ink.
[0037]
Furthermore, in the above-described embodiment, the corner formed between the bottom surface and the side surface of the groove 2a formed in the insulating layer 2 is formed into a curved surface, and the radius of curvature is set to 5.0 μm to 50.0 μm. If this is done, the inner surface of the groove becomes a smooth curved surface with no corners.Therefore, cracks do not occur in the single crystal silicon wafer starting from the corners existing on the inner surface of the groove. The quality of the recording head including the head can be improved.
[0038]
Furthermore, in the above-described embodiment, the heating resistor 3 and a pair of electrodes (not shown) may be covered with a protective film made of silicon nitride, silicon oxide, or the like. At this time, a recess may be provided in the protective film located at the boundary between adjacent sections. In this case, the linear expansion coefficient between the silicon nitride or the like constituting the protective film and the single crystal silicon wafer 1a is reduced. A part of the thermal stress resulting from the difference is also released moderately from the concave portion formed in the protective film, so that chipping and warping of the thermal head can be more effectively prevented. Further, as shown in FIG. 6 (c), if the concave portion 5a is formed wider than the groove 2a, when the single crystal silicon wafer 1a is diced, the diamond blade hits the side surface of the concave portion 5a and the protective film 5 is peeled off. There is also an advantage that such a problem can be effectively prevented. Therefore, it is preferable to form the recess 5a wider than the groove 2a. The protective film 5 is formed by employing a conventionally well-known CVD (Chemical Vapor Deposition) method or a thin film forming technique such as sputtering, and the recess 5a is formed as shown in FIG. 6 or FIG. After forming 5, the protective film 5 is formed into a predetermined pattern by a conventionally known photolithography technique and etching technique.
[0039]
【The invention's effect】
According to the recording head manufacturing method of the present invention, the insulating layer is formed on the upper surface of the single crystal silicon wafer divided into a plurality of elongated sections, and the insulation located at the boundary between adjacent sections is formed. Since a groove is formed in the layer and silicon is exposed on the bottom surface of the groove, a part of the thermal stress accumulated in the single crystal silicon wafer is appropriately released from the boundary portion. The amount of thermal stress in the single crystal silicon wafer that is released at one time during the cutting can be reduced. Therefore, the degree of curvature of the recording head obtained by dicing the single crystal silicon wafer can be reduced, the linearity of the arrangement of the heating resistors can be maintained well, and a good image with little distortion with respect to the recording paper Can be obtained.
[0040]
In addition, in this case, since the single crystal silicon wafer is diced at the bottom surface of the groove where the accumulated amount of thermal stress is small, the problem that chipping occurs at the corner of the obtained recording head and the heating resistor is missing is effective. Therefore, the yield of the recording head can be improved.
[0041]
According to the recording head manufacturing method of the present invention, since the groove is formed at the boundary portion between adjacent sections, there is a step between the bottom surface of the groove and the upper surface of the insulating layer in the vicinity of the groove. Thus, when dicing a single crystal silicon wafer, if an excessively large pressing force is applied to the single crystal silicon wafer and chipping occurs in the recording head, such chipping may occur on the top surface of the insulating layer. The heating resistor is hardly chipped and the yield of the recording head can be further increased.
[0042]
Furthermore, according to the recording head manufacturing method of the present invention, the long sides of the plurality of elongated sections formed on the upper surface of the single crystal silicon wafer are in the <110> direction where the mechanical strength of the single crystal silicon wafer is high. By arranging so as to be substantially parallel to the recording head, the frequency of occurrence of chipping in the recording head obtained from the single crystal silicon wafer is further reduced, and the yield of the recording head is remarkably improved, and the recording head is generated. The amount of warpage is further reduced, and the image formed on the recording paper can be made clearer.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a thermal head manufactured by using the recording head manufacturing method of the present invention.
2 is a cross-sectional view of a thermal head manufactured by the manufacturing method of FIG.
FIG. 3 is a cross-sectional view for each step for explaining a method of manufacturing a recording head according to an embodiment of the invention.
4 is a plan view of a silicon wafer used in the method for manufacturing the recording head of FIG. 3. FIG.
FIGS. 5A to 5E are cross-sectional views for each step for explaining a method of manufacturing a recording head.
FIGS. 6A to 6C are cross-sectional views for each step for explaining a method of forming a protective film and a recess.
FIGS. 7A and 7B are cross-sectional views for each step for explaining another method of forming a protective film and a recess. FIGS.
FIG. 8 is a cross-sectional view of a thermal head manufactured by a conventional manufacturing method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Silicon substrate 1a ... Single crystal silicon wafer 2 ... Insulating layer 2a ... Groove 3 ... Heating resistor 5 ... Protective film 5a ... Concave part

Claims (6)

Forming an insulating layer on the upper surface of the single crystal silicon wafer divided into a plurality of elongated sections;
Attaching and arranging a number of heating resistors in a straight line by a thin film forming technique along the long side of each section; and
A groove is formed by etching in the insulating layer located at the boundary between the adjacent sections, and silicon is exposed on the bottom surface of the groove, and the corner formed between the bottom surface and the side surface of the groove is curved. And a process of
And a step of dicing the single crystal silicon wafer at the bottom surface of the groove to divide the single crystal silicon wafer into respective sections to obtain a plurality of recording heads. 2. The method of manufacturing a recording head according to claim 1 , wherein the long section has a long side substantially parallel to a <110> direction of the single crystal silicon wafer. The insulating layer, the manufacturing method of the recording head according to claim 1 or 2, characterized in that it is formed by oxidizing by thermal oxidation the upper surface of the single crystal silicon wafer. Method of manufacturing a recording head as claimed in any of claims 1 to 3, the radius of curvature at the corner portion, characterized in that it is set to 5.0Myuemu～50.0Myuemu. Forming a protective film covering at least the heating resistor and made of silicon nitride or silicon oxide by a thin film forming technique;
Wherein a recess portion which is located in the groove in the protective layer, a recording head according forming by photolithography and etching, from claim 1, further comprising a One to either 4 Manufacturing method. 6. The method of manufacturing a recording head according to claim 5 , wherein the width of the concave portion of the protective film is set wider than the width of the groove.

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