JP2760988B2 - Hybrid board - Google Patents

Description

The present invention relates to a hybrid substrate for an active element having a fine pattern. [Prior Art] Conventionally, alumina, silicon, or the like has been used for a substrate of a large-area active element having a fine pattern such as a thermal head or an inkjet head. [Problems to be Solved by the Invention] However, it is impossible to form an element having a fine line width of about 10 μm due to poor surface flatness of an alumina substrate. In order to improve the surface flatness, a coating of molten glass on the surface of alumina is also made, but the thermal conductivity of glass is about the same as that of alumina.
It is considerably worse, 1/20, and it is difficult to control the heat generation of the element at a high frequency by the heat storage effect when a heat-generating element is formed thereon. A silicon wafer has good surface flatness but is expensive. Polysilicon wafers are also somewhat less expensive than polysilicon wafers, but have the disadvantage of having significantly lower mechanical strength. SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a low-cost hybrid substrate having good surface flatness. [Means for Solving the Problems] The gist of the present invention is to provide a hybrid substrate in which a plurality of patterned heating elements are formed on a surface, wherein the hybrid substrate has a layer thickness of 20 μm or more on a ceramic substrate.
The hybrid substrate has an Si layer over a region where the plurality of heating elements are formed. [Operation] The present invention compensates for the disadvantages of each of the above by depositing amorphous or polycrystalline silicon of 20 μm or more on a polycrystalline ceramic substrate. Conventionally, sensors and solar cells with thin (less than 10 μm) polycrystalline or amorphous silicon deposited on a ceramic substrate have been reported, but these are semiconductor-grade films deposited at low speed and are essentially This is different from the present invention. EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples. Example 1 FIG. 1 is an example of the present invention, and is a process diagram when a polysilicon film is grown by CVD on an alumina substrate and flattened to form a hybrid substrate. Hereinafter, each step will be described. (A) On an unpolished alumina substrate 1, a polysilicon 2 having a particle size capable of filling the surface irregularities is deposited while controlling the nucleation density. The deposition is performed by first cleaning the surface by flowing HCl gas to the high-temperature alumina substrate 1 and then diluting with H ₂ SiCl ₄ and SiH ₂ Cl _2.
The reaction is performed at a substrate temperature (900 to 1100 ° C.) under reduced pressure (about 150 Torr) using a reaction gas such as the above. The deposition rate at this time is 40
6060 μm / hr. (B) Polysilicon of about 50 μm is deposited in about 40 minutes, and the irregularities on the surface of the alumina substrate 1 are completely covered. (C) Next, mechanical polishing is performed to improve the flatness of the surface of the alumina substrate 1, and the polysilicon is ground to a thickness of about 30 μm. It is used and the growth rate of polysilicon is high, so that the throughput is increased. Embodiment 2 As a second embodiment of the present invention, an amorphous silicon film or a
A method for forming a hybrid substrate by depositing a polysilicon film will be described. FIG. 2A is a configuration diagram of a microwave plasma CVD apparatus. The aluminum nitride substrate 21 is arranged on the circumference with the deposition surface facing inward, SiH ₄ gas is introduced from the center, and the microwave 23 is applied from above and below to perform plasma CVD. FIG. 2 (b) shows a manufacturing process of the hybrid substrate. (A) An aluminum nitride substrate 21 having a rough surface is (b) wrapped with a rough wrap to remove extreme irregularities. (C) Next, amorphous silicon or polysilicon 24 is deposited to a thickness of about 30 μm by microwave plasma CVD. The deposition conditions were 250 mm x 60 mm aluminum nitride substrates, 6
₄ 170 ~ 340sccm, substrate temperature 200 ~ 480 ℃, pressure 0.5 ~ 20mTor
r Use microwave power between 500W and 2kW. Deposition time is 20 ~
In about 40 minutes, about 30 μm can be deposited. When the substrate temperature exceeds 380 ° C., the film becomes polysilicon. The hybrid substrate formed by the above steps does not need to be polished because the amorphous silicon or polysilicon film has good surface properties. Embodiment 3 FIG. 3 is a diagram showing a manufacturing apparatus when a polysilicon is formed by removing molten silicon on an alumina substrate and flattening the polysilicon to form a hybrid substrate. That is, it is composed of a part where silicon is melted and dropped at high temperature and a holder part which rotates by heating the alumina substrate. Hereinafter, a manufacturing process of the hybrid substrate will be described. In FIG. 3, a quartz crucible 4 (surrounded by graphite 5) is heated to 1450 ° C. by a carbon heater 8 to melt the silicon 6. The molten silicon can be dropped through the quartz funnel 7 and is dropped onto the alumina substrate 9. The alumina substrate 9 is placed on the rotary holder 10 and is
Rotate at 00rpm, 1000 ~ 1400 ℃ with carbon heater 11
Heating. Therefore, the silicon 6 removed on the ceramic substrate 9
Is spread on the alumina substrate 9 by centrifugal force and becomes a polycrystal with a thickness of 0.2 to 0.5 mm and solidifies. This is mechanically polished similarly to the embodiment shown in FIG. A process for forming a thermal head on a ceramic / silicon hybrid substrate manufactured by the above-described manufacturing method will be described. FIG. 4 shows the structure of the thermal head. TaN42 is deposited on a ceramic / silicon hybrid substrate by sputtering at a thickness of 1000. Next, 5000 nm of Al43 is deposited by a sputtering method. A pattern (FIG. 4 (a)) having a heater size of 50 μm × 20 μm is formed by photolithography. Further antioxidant layer 44
SiO ₂ is deposited by sputtering with a thickness of 1 μm, and Ta ₂ O ₅ is deposited as a wear-resistant layer 45 with a thickness of 3 μm by sputtering. FIG. 4 (b) shows a cross-sectional configuration of the thermal head prepared as described above. The characteristics of the hybrid substrates obtained according to the first to third embodiments are described in Table 1 together with those of the conventional example. As shown in Table 1, the hybrid substrate according to the present invention met a certain level in all aspects of flatness, workability, strength, thermal conductivity, uniformity, and cost. [Effects of the Invention] As described above, according to the present invention, a certain level is required in all aspects of flatness, workability, high thermal conductivity, uniformity, and cost required for a heat-generating large-area active element. A satisfactory hybrid substrate can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing a manufacturing process of a hybrid substrate by a thermal CVD method according to an embodiment of the present invention, and FIG. 2 is an embodiment of the present invention; FIG. 3 is a manufacturing process diagram of a hybrid substrate, and FIG. FIG. 4 (a) is a plan view when a thermal head is formed on the hybrid substrates manufactured according to the first to third embodiments, and FIG. 4 (b) is an XY cross-sectional view thereof. DESCRIPTION OF SYMBOLS 1 ... Alumina substrate, 2 ... Polysilicon crystal grain, 3 ... Polysilicon film, 4 ... Quartz crucible, 5 ... Graphic crucible, 6 ... Silicon, 7 ... Quartz funnel, 8 ... Carbon heater, 9 ... Alumina substrate, 10 ... Rotation Type board holder, 11
... Carbon heater, 21 ... Aluminum nitride substrate, 22 ... Ceramic waveguide window, 23 ... Side wave, 24 ... Polysilicon film or amorphous silicon film, 40 ... Ceramic substrate, 41 ... Polysilicon layer, 42 ... TaN, 43 ... Al , 44… SiO ₂ , 45… Ta ₂ O ₅ .

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-55-99793 (JP, A) JP-A-61-211057 (JP, A) JP-A-62-203325 (JP, A) JP-A 53-99 125852 (JP, A) JP-A-63-84946 (JP, A) JP-A-62-134270 (JP, A) JP-A-61-56401 (JP, A) JP-A-63-55901 (JP, A) JP-A-63-70513 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41J 2/335 B41J 2/05 H01L 23/14 H01L 49/00 H05K 1/16

Claims (1)

(57) [Claims] In a hybrid substrate in which a plurality of patterned heating elements are formed on the surface, the hybrid substrate has a Si layer having a thickness of 20 μm or more on a ceramic substrate over a region where the plurality of heating elements are formed. Hybrid substrate. 2. The hybrid substrate according to claim 1, wherein the Si layer is made of polysilicon or amorphous silicon. 3. The hybrid substrate according to claim 1, wherein the surface of the Si layer is polished.