Method of fabricating a pyroelectric infrared detector

Abstract: A pyroelectric infrared detector includes a substrate having a recess. A pyroelectric portion substantially aligns with the recess. A resin film is located between the substrate and the pyroelectric portion. The recess faces the resin film. First and second electrodes are connected to first and second surfaces of the pyroelectric portion respectively. The pyroelectric portion may include a pyroelectric film of Pb x La y Ti z Zr w O₃ where atomic fractions "w", "x", "y", and "z" satisfy one of following conditions a), b), and c): a) 0.7≦x≦1, x+y=1, 0.925≦z≦1, w=0 b) x=1, y=0, 0.45≦z<1, z+w=1 c) 0.75≦x<1, x+y=1, 0.5≦z<1, z+w=1

Description: BACKGROUND OF THE INVENTION Field of the Invention This invention relates to a pyroelectric infrared detector. This invention also relates to a method of fabricating a pyroelectric infrared detector. Description of the Prior Art R. Takayama et al reported high sensitive pyroelectric linear array infrared sensors fabricated by using highly c-axis-oriented and spontaneous polarized La-modified PbTiO 3 (PLT) thin films (Journal of Applied Physics 63(12), 15 June 1988, p5868-5872). The PLT thin films were deposited on (100)-orientated Pt thin film on (100)-cleaved MgO single crystals by RF magnetron sputtering. The PLT thin films had high figures of merit for voltage responsivity (Rv) and specific detectivity (D*) without a poling treatment. Since the pyroelectric infrared sensor reported by R. Takayama et al uses an MgO single crystal as a substrate, it is generally difficult to form the pyroelectric film and an external circuit on a common substrate. The MgO substrate has a high thermal conductivity. Thus, a portion of the MgO substrate which extends directly below a major part of the pyroelectric film is etched off to suppress heat transfer from the pyroelectric film to the substrate to attain a high infrared sensitivity. Japanese published unexamined patent application 4-170077 discloses a pyroelectric infrared detector fabricated as follows. A pyroelectric film was formed on a first substrate made of an MgO single crystal. The pyroelectric film and exposed portions of the first substrate were coated with an organic film. A second substrate having a central opening was bonded to the organic film by adhesive. Finally, the first substrate was etched off to complete the pyroelectric infrared detector in which the pyroelectric film was supported on the second substrate via the organic film. The pyroelectric film was located above the opening in the second substrate. In the pyroelectric infrared detector of Japanese application 4-170077, the pyroelectric film was made of Pb x La y Ti z Zr w O 3 where the atomic fractions "x", "y", "z", and "w" satisfied one of the following three different conditions (a), (b), and (c): (a) 0.7≦x≦1, 0.9≦x+y<1, 0.95≦z≦1, w=0 (b) x=1, y=0, 0.45≦z<1, z+w=1 (c) 0.83≦x≦1, x+y=1, 0.5≦z<1, 0.96≦z+w≦1 During the fabrication of the pyroelectric infrared detector of Japanese application 4-170077, the first substrate made of MgO was etched off as previously described. Generally, the removal of the MgO substrate is disadvantageous in cost and time. The opening extends through walls of the second substrate. Thus, during the etching process, etchant tended to reach the organic film and the pyroelectric film via the opening in the second substrate. In this case, the etchant adversely affected the organic film and the pyroelectric film. In some cases, the pyroelectric film was broken. Thus, it is difficult to improve the yield of detectors. On the other hand, JP-A-57-104380 discloses an infrared ray solid-state image pick-up device comprising a substrate consisting of Si-crystal layers 4, 6 of p-type which sandwich an impurity layer 5 of p + -type. This semiconductor substrate is covered with an isolation layer 8 on which a pyroelectric crystal 12 is provided. For decreasing the heat capacitance and improving the sensitivity of the sensor, Si crystal 6 under the isolation film 8 is corroded. Thus, an infrared ray solid-state image pick-up device is obtained. Further, EP-A-0 417 846 relates to an infrared detector element (20) comprising a flexible continuous film (10) and a mounting arrangement for the film consisting of mutually-spaced supports (32) of a molded plastic substrate (30), thereby forming cavities (35). Moreover, US-A-4,532,424 discloses a thermal detector array including a Si substrate layer to which a pyroelectric layer is attached. A plurality of detector regions are defined in the pyroelectric layer by etching cavities into the surface of the pyroelectric layer. Therefore, a continuous pyroelectric layer is not provided, facilitating heat transfer to the respective pyroelectric portions. SUMMARY OF THE INVENTION It is an object of this invention to provide an improved pyroelectric infrared detector. It is another object of this invention to provide an improved method of fabricating a pyroelectric infrared detector. Therefore, this invention provides a method of fabricating a pyroelectric infrared detector which comprises the steps of forming an under layer film of oriented oxide on a first substrate; forming a pyroelectric portion on a given area of a surface of the under layer film; forming a resin film covering the pyroelectric portion and an exposed area of the surface of the under layer film; bonding a second substrate to the resin film; and etching off the under layer film to remove the first substrate from the pyroelectric portion and the resin film. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a sectional view of a pyroelectric infrared detector according to Example 1 of this invention. Figs. 2(a)-2(g) are sectional views of a detector substrate in various states which occur at respective steps in the fabrication of the pyroelectric infrared detector according to Example 1 of this invention. Fig. 3 is a diagram of a plasma-enhanced MO-CVD apparatus used in the fabrication of the pyroelectric infrared detector according to Example 1 of this invention. Fig. 4 is a diagram of an x-ray diffraction pattern of a sample of a pyroelectric film in the pyroelectric infrared detector according to Example 1 of this invention. Fig. 5 is a diagram of an x-ray diffraction pattern of a sample of a pyroelectric film in a pyroelectric infrared detector according to Example 2 of this invention. Fig. 6 is a diagram of a plasma-enhanced MO-CVD apparatus used in the fabrication of a pyroelectric infrared detector according to Example 5 of this invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, a method of fabricating a pyroelectric infrared detector includes the steps of forming an under layer film of oriented oxide on a first substrate; forming a pyroelectric portion on a given area of a surface of the under layer film; forming a resin film covering the pyroelectric portion and an exposed area of the surface of the under layer film; bonding a second substrate to the resin film; and etching off the under layer film to remove the under layer film and the first substrate from the pyroelectric portion and the resin film. The under-layer-film forming step may include depositing the under layer film on the first substrate by a plasma-enhanced MO-CVD process, and using a vapor of an organometallic complex as a source gas. The under-layer-film forming step may include depositing the under layer film on the first substrate by a sputtering process. The under layer film may be made of a material which allows the pyroelectric portion to be oriented in a direction of polarization, and which can be easily etched off. The under layer film may have a crystal structure of an NaCl type. The under layer film may be made of MgO or NiO. Example 1 With reference to Fig. 1, a pyroelectric infrared detector according to Example 1 includes a substrate 37 which has a central opening or hole 37a extending therethrough. A resin film 35 extending above the substrate 37 is bonded to the substrate 37 via an adhesive layer 36. The adhesive layer 36 extends outward of the opening 37a. The adhesive layer 36 is sandwiched between the substrate 37 and the resin film 35. An upper surface of the resin film 35 has a recess filled with a pyroelectric film 33. An upper surface of the pyroelectric film 33 is substantially flush with the upper surface of the resin film 35. An electrode layer 34 extends between a lower surface of the pyroelectric film 33 and the resin film 35, extending upward along a side of the pyroelectric film 33 and then extending outward along the upper surface of the resin film 35. Another electrode layer 38 extends on a given area of the upper surface of the pyroelectric film 33, and then extends outward along the upper surface of the resin film 35. In this way, the electrode layers 34 and 38 are electrically connected to the lower and upper surfaces of the pyroelectric film 33 respectively. The substrate 37 is spaced from the resin film 35 by the adhesive layer 36. The substrate 37, the resin film 35, and the adhesive layer 36 define a downwardly-facing recess, the lower portion of which is formed by the opening 37a in the substrate 37. The pyroelectric film 33 substantially aligns with the downwardly-facing recess. In addition, the pyroelectric film 33 is located above the downwardly-facing recess, and is separated therefrom by the resin film 35. Accordingly, the resin film 35 and the downwardly-facing recess suppress the escape of heat from the pyroelectric film 33 to the substrate 37. This design enables a high infrared sensitivity. The pyroelectric film 33 is made of Pb 0.9 La 0.1 Ti 0.975 O 3 . The electrode layers 34 and 38 are made of Ni-Cr. The resin film 35 is made of polyimide resin. The adhesive layer 36 is made of epoxy resin or silicone resin. The substrate 37 is made of alumina (Al 2 O 3 ). The pyroelectric infrared detector of Fig. 1 was fabricated as follows. With reference to Fig. 2(a), a first substrate 31 made of stainless steel was prepared. The first substrate 31 had a thermal expansion coefficient of 18 × 10 -6 °C -1 . An oxide under layer film 32 made of a (100) oriented MgO crystal was formed on the first substrate 31 by a plasma-enhanced MO-CVD apparatus. The oxide under layer film 32 had a crystal structure of the NaCl type. Specifically, as shown in Fig. 3, the first substrate 31 was placed in a reaction chamber 41 of the plasma-enhanced MO-CVD apparatus. The first substrate 31 was previously heated at a temperature of 350°C by a heater 49. The first substrate 31 was supported on a ground electrode 42b. Magnesium acetylacetonate, Mg(C 5 H 7 O 2 ) 2 , was placed in a source vaporizer 46 and was heated by using an oil bath held at a temperature of 190°C. Magnesium acetylacetonate was vaporized as being heated. Resultant magnesium acetylacetonate vapor was driven into the reaction chamber 41 by using carrier nitrogen gas which flowed from a carrier gas cylinder 47 at a rate of 10 ml/min. Oxygen gas serving as reactant gas flowed from a reactant gas cylinder 48 at a rate of 12 ml/min, and was driven into the reaction chamber 41 via an injection nozzle. The reaction chamber 41 was exhausted via an exhaust system 43 so that the pressure in the reaction chamber 41 was held equal to a vacuum of 7.90 Pa. Under these conditions, electromagnetic wave having a frequency of 13.56 MHz was applied from an RF power source 45 to an RF electrode 42a at a power of 400 W for 10 minutes so that plasma was generated between the RF electrode 42a and the ground electrode 42b in the reaction chamber 41 of the plasma-enhanced MO-CVD apparatus. As a result, an MgO under layer film 32 was deposited on a surface of the first substrate 31. The oxide under layer film 32 was made of MgO polycrystal which had an NaCl-type structure and which was oriented along a <100>-axis in the vertical direction of the first substrate 31. The oxide under layer film 32 had a thickness of 2,000 angstroms. During the formation of the oxide under layer film 32, the first substrate 31 was rotated at 120 r.p.m. by a motor (not shown). With reference to Fig. 2(b), after the oxide under layer film 32 was formed on the first substrate 31, a pyroelectric film 33 made of Pb 0.9 La 0.1 Ti 0.975 O 3 was formed on the oxide under layer film 32 by the use of a RF magnetron sputtering apparatus. Specifically, the first substrate 31 having the oxide under layer film 32 formed thereon was provided with a stainless mask having a thickness of 0.2 mm and having a configuration corresponding to a desired shape of the pyroelectric film 33. The first substrate 31 with the mask was attached to a stainless holder in the RF magnetron sputtering apparatus. A mixture of PbO powder, La 2 O 3 powder, and TiO 2 powder was used as a target placed in a copper dish in the RF magnetron sputtering apparatus. The mixing ratio among the PbO powder, the La 2 O 3 powder, and the TiO 2 powder was chosen so that the amount of the PbO powder was in excess of the amount corresponding to the composition of the pyroelectric film 33 by 20 mol%. The RF magnetron sputtering apparatus was activated so that a pyroelectric film 33 was deposited on a given area (an exposed area) of the oxide under layer film 32 by sputtering. During the sputtering, the first substrate 31 remained heated at a temperature of 600°C. Furthermore, sputtering gas composed of a mixture of argon (90%) and oxygen (10%) was used in the RF magnetron sputtering apparatus. The pressure of the sputtering gas was equal to 0.9 Pa. The RF power density in the RF magnetron sputtering apparatus was equal to 2.0 W/cm 2 . The RF power had a frequency of 13.56 MHz. The pyroelectric film 33 had a thickness of 3 µm. After the formation of the pyroelectric film 33, an Ni-Cr film having a thickness of 100 nm was formed on the pyroelectric film 33 and a given area of the oxide under layer film 32 by sputtering. As shown in Fig. 2(c), the Ni-Cr film was made into an electrode layer 34 and extensions thereof by a patterning process using photolithography. Subsequently, as shown in Fig. 2(d), polyimide resin was applied to exposed areas of the oxide under layer film 32, the electrode layer 34, and the pyroelectric film 33 by spin coat, being polymerized into a resin film 35. As shown in Fig. 2(e), silicone resin or epoxy resin forming an adhesive layer 36 was applied to given areas of the resin film 35. Then, a second substrate 37 was attached to the resin film 35 on the first substrate 31 by the adhesive layer 36. The adhesive layer 36 was polymerized, completely bonding the resin film 35 and the second substrate 37 together. The second substrate 37 had a central opening or hole 37a located below the pyroelectric film 33. The second substrate 37 was made of alumina (Al 2 O 3 ). Subsequently, the oxide under layer film 32 was etched off by etchant such as an aqueous solution of orthophosphoric acid. Thus, as shown in Fig, 2(f), the first substrate 31 was removed from the pyroelectric film 33, the resin film 35, and the electrode layer 34. Finally, as shown in Fig. 2(g), an Ni-Cr film having a thickness of 10 nm was formed on given regions of exposed areas of the pyroelectric film 33 and the resin film 35, being made into an electrode layer 38 and extensions thereof by a patterning process. Since the exposed areas of the pyroelectric film 33 and the resin film 35 were flat and flush with each other, the patterning of the electrode layer 38 was easy. The second substrate 37 was previously provided with a wiring pattern made of Ag-Pd conductive paste. This design enabled the pyroelectric film 33 and a peripheral circuit (an external circuit) to be mounted on a common substrate, that is, the second substrate 37. Therefore, the pyroelectric infrared detector was small in size. The first substrate 31 was automatically removed by etching off the oxide under layer film 32. The polycrystalline state of the oxide under layer film 32 enabled an etching rate significantly greater than the etching rate related to an MgO single crystal. Thus, the time necessary for the etching process was relatively short, and was equal to about 70 minutes. The oxide under layer film 32 was etched off along directions (inward directions) from the sides to the center thereof. The short time for the etching was advantageous in uniformness of the etching and in protecting the pyroelectric film 33 from the etchant. Samples of the pyroelectric infrared detector according to Example 3 were prepared. Experiments were performed on these samples which were not subjected to a poling treatment. With respect to the samples, the productive yield was equal to 91%. The sensing portions of the samples had a pyroelectric coefficient "γ" of 3.4 × 10 -8 C/cm 2 K, a relative dielectric constant εr of 179, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the samples had a merit figure Fv (=γ/Cvεr)of 0.59 × 10 -10 Ccm/J. The relative dielectric constant of each of the samples was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the samples was represented by an average value in a temperature variation between 20-30°C. A sample of the Pb 0.9 La 0.1 Ti 0.975 O 3 pyroelectric film 33 was prepared on the (100) oriented MgO under layer film 32. Experiments were performed to analyze this sample by x-ray diffraction. Fig. 7 shows an experimentally-obtained x-ray diffraction pattern of the sample in which (001), (100), (002), and (200) denote the intensities of reflection at related crystal planes. The rate or percentage "α" of the c-axis orientation of the sample was calculated by referring to the following equation: α(%) = I(001) I(001)+I(100)+I(101)+I(111)+I(110) × 100 where I(001), I(100), I(101), I(111), and I(110) denoted the intensities of reflection at crystal planes (001), (100), (101), (111), and (110) respectively. The result of the calculation of the rate "α" was equal to 90%. It should be noted that the c-axis orientation means (001)-plane orientation. Example 2 A pyroelectric infrared detector according to Example 2 is similar to the pyroelectric infrared detector of Example 1 (see Figs. 1 and 2(a)-2(g)) except for design changes indicated hereinafter. During the fabrication of the pyroelectric infrared detector of Example 2, an oxide under layer film 32 made of a (100) oriented NiO was formed on a first substrate 31 by a plasma-enhanced MO-CVD apparatus. The oxide under layer film 32 had a crystal structure of the NaCl type. Specifically, as shown in Fig. 3, the first substrate 31 was placed in a reaction chamber 41 of the plasma-enhanced MO-CVD apparatus. The first substrate 31 was previously heated at a temperature of 350°C by a heater 49. The first substrate 31 was supported on a ground electrode 42b. Nickel acetylacetonate, Ni(C 5 H 7 O 2 ) 2 H 2 O, was placed in a source vaporizer 46 and was heated by using an oil bath held at a temperature of 160°C. Nickel acetylacetonate was vaporized as being heated. Resultant nickel acetylacetonate vapor was driven into the reaction chamber 41 by using carrier nitrogen gas which flowed from a carrier gas cylinder 47 at a rate of 35 ml/min. Oxygen gas serving as reactant gas flowed from a reactant gas cylinder 48 at a rate of 15 ml/min, and was driven into the reaction chamber 41 via an injection nozzle. The reaction chamber 41 was exhausted via an exhaust system 43 so that the pressure in the reaction chamber 41 was held equal to a vacuum of 7.90 Pa. Under these conditions, electromagnetic wave having a frequency of 13.56 MHz was applied from an RF power source 45 to an RF electrode 42a at a power of 400 W for 10 minutes so that plasma was generated between the RF electrode 42a and the ground electrode 42b in the reaction chamber 41 of the plasma-enhanced MO-CVD apparatus. As a result, an NiO under layer film 32 was deposited on a surface of the first substrate 31. The oxide under layer film 32 was made of NiO polycrystal which had an NaCl-type structure and which was oriented along a <100>-axis in the vertical direction of the first substrate 31. The oxide under layer film 32 had a thickness of 2,000 angstroms. During the formation of the oxide under layer film 32, the first substrate 31 was rotated at 120 r.p.m. by a motor (not shown). After the oxide under layer film 32 was formed on the first substrate 31, a pyroelectric film 33 made of Pb 0.9 La 0.1 Ti 0.975 O 3 was formed on the oxide under layer film 32 by RF magnetron sputtering as in Example 1. During a later stage, the NiO under layer film 32 was etched off as the MgO under layer film 32 was removed in Example 1. The time necessary for the etching process was equal to about 75 minutes. Samples of the pyroelectric infrared detector according to Example 2 were prepared. Experiments were performed on these samples which were not subjected to a poling treatment. With respect to the samples, the productive yield was equal to 90%. The sensing portions of the samples had a pyroelectric coefficient "γ" of 3.3 × 10 -8 C/cm 2 K, a relative dielectric constant εr of 176, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the samples had a merit figure Fv (=γ/Cvεr)of 0.59 × 10 -10 Ccm/J. The relative dielectric constant of each of the samples was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the samples was represented by an average value in a temperature variation between 20-30°C. A sample of the Pb 0.9 La 0.1 Ti 0.975 O 3 pyroelectric film 33 was prepared on the (100) oriented NiO under layer film 32. Experiments were performed to analyze this sample by x-ray diffraction. Fig. 8 shows an experimentally-obtained x-ray diffraction pattern of the sample in which (001), (100), (002), and (200) denote the intensities of reflection at related crystal planes. The rate or percentage "o" of the c-axis orientation of the sample was calculated by referring to the previously-mentioned equation (1). The result of the calculation of the rate "α" was equal to 90%. It should be noted that the c-axis orientation means (001)-plane orientation. Example 3 A pyroelectric infrared detector according to Example 3 is similar to the pyroelectric infrared detector of Example 1 except that a substrate 37 (see Fig. 1) has a recess instead of a through hole (a through opening). Samples of the pyroelectric infrared detector according to Example 3 were prepared. Experiments were performed on these samples which were not subjected to a poling treatment. With respect to the samples, the productive yield was equal to 90%. The sensing portions of the samples had a pyroelectric coefficient "γ' of 3.4 × 10 -8 C/cm 2 K, a relative dielectric constant εr of 180, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the samples had a merit figure Fv (=γ/Cvεr) of 0.59 × 10 -10 Ccm/J. The relative dielectric constant of each of the samples was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the samples was represented by an average value in a temperature variation between 20-30°C. Example 4 A pyroelectric infrared detector according to Example 4 is similar to the pyroelectric infrared detector of Example 2 except that a substrate 37 (see Fig. 1) has a recess instead of a through hole (a through opening). Samples of the pyroelectric infrared detector according to Example 4 were prepared. Experiments were performed on these samples which were not subjected to a poling treatment. With respect to the samples, the productive yield was equal to 92%. The sensing portions of the samples had a pyroelectric coefficient "γ" of 3.3 × 10 -8 C/cm 2 K, a relative dielectric constant εr of 175, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the samples had a merit figure Fv (=γ/Cvεr) of 0.59 × 10 -10 Ccm/J. The relative dielectric constant of each of the samples was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the samples was represented by an average value in a temperature variation between 20-30°C. Example 5 A pyroelectric infrared detector according to Example 5 is similar to the pyroelectric infrared detector of Example 1 except for design changes indicated hereinafter. In the pyroelectric infrared detector of Example 5, a substrate 37 (see Fig. 1) has a recess instead of a through hole (a through opening). In addition, a pyroelectric film 33 (see Fig. 1) is made of PbTiO 3 . During the fabrication of the pyroelectric infrared detector of Example 5, the pyroelectric film 33 made of PbTiO 3 was formed on an oxide under layer film 32 by using a plasma-enhanced MO-CVD apparatus. Specifically, as shown in Fig. 6, a first substrate 31 was placed in a reaction chamber 51 of the plasma-enhanced MO-CVD apparatus. The first substrate 31 was previously heated at a temperature of 450°C by a heater 511. The first substrate 31 was supported on a ground electrode 52b. Lead dipivaloyl methane. Pb(C 11 H 19 O 2 ) 2 , was placed in a source vaporizer 57 and was heated by using an oil bath held at a temperature of 130°C. Lead dipivaloyl methane was vaporized as being heated. Titanium tetra-isopropoxide, Ti(i-C 3 H 7 O) 4 , was placed in a source vaporizer 58 and was heated by using an oil bath held at a temperature of 50°C. Titanium tetra-isopropoxide was vaporized as being heated. Resultant lead dipivaloyl methane vapor and titanium tetra-isopropoxide vapor were driven into the reaction chamber 51 by using carrier nitrogen gas which flowed from a carrier gas cylinder 59 at a rate of 10 ml/min. Oxygen gas serving as reactant gas flowed from a reactant gas cylinder 510 at a rate of 40 ml/min, and was driven into the reaction chamber 51 via an injection nozzle. The reaction chamber 53 was exhausted via an exhaust system 53 so that the pressure in the reaction chamber 51 was held equal to a vacuum of 3.90 Pa. Under these conditions, electromagnetic wave having a frequency of 13.56 MHz was applied from an RF power source 55 to an RF electrode 52a at a power of 400 W for 100 minutes so that plasma was generated between the RF electrode 52a and the ground electrode 52b in the reaction chamber 51 of the plasma-enhanced MO-CVD apparatus. As a result, a (100) oriented PbTiO 3 pyroelectric film 33 was deposited on a surface of the first substrate 11. The PbTiO 3 pyroelectric film 33 had a thickness of 3 µm. During the formation of the PbTiO 3 pyroelectric film 33, the first substrate 31 was rotated at 120 r.p.m. by a motor (not shown). In the plasma-enhanced MO-CVD apparatus of Fig. 6, a source vaporizer 56 contained Mg(C 11 H 19 O 2 ) 2 for an under layer. Thus, it is possible to form the under layer and the pyroelectric film by using the same apparatus. This is effective to shorten the process time of forming the films. Samples of the pyroelectric infrared detector according to Example 5 were prepared. Experiments were performed on these samples which were not subjected to a poling treatment. With respect to the samples, the productive yield was equal to 91%. The sensing portions of the samples had a pyroelectric coefficient "γ' of 2.0 × 10 -8 C/cm 2 K, a relative dielectric constant εr of 105, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the samples had a merit figure Fv (=γ/Cvεr)of 0.60 × 10 -10 Ccm/J. The relative dielectric constant of each of the samples was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the samples was represented by an average value in a temperature variation between 20-30°C. Example 6 A pyroelectric infrared detector according to Example 6 is similar to the pyroelectric infrared detector of Example 2 except for design changes indicated hereinafter. In the pyroelectric infrared detector of Example 6, a substrate 37 (see Fig. 1) has a recess instead of a through hole (a through opening). In addition, a pyroelectric film 33 (see Fig. 1) is made of PbTiO 3 . During the fabrication of the pyroelectric infrared detector of Example 8, the pyroelectric film 33 made of PbTiO 3 was formed on an oxide under layer film 32 by using a plasma-enhanced MO-CVD apparatus as in Example 5. Samples of the pyroelectric infrared detector according to Example 6 were prepared. Experiments were performed on these samples which were not subjected to a poling treatment. With respect to the samples, the productive yield was equal to 90%. The sensing portions of the samples had a pyroelectric coefficient "γ' of 1.9 × 10 -8 C/cm 2 K, a relative dielectric constant εr of 100, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the samples had a merit figure Fv (=γ/Cvεr)of 0.59 × 10 -10 Ccm/J. The relative dielectric constant of each of the samples was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the samples was represented by an average value in a temperature variation between 20-30°C. Example 7 A pyroelectric infrared detector according to Example 7 is similar to the pyroelectric infrared detector of Example 1 (see Figs. 1 and 2(a)-2(g)) except for design changes indicated hereinafter. During the fabrication of the pyroelectric infrared detector of Example 7, an oxide under layer film 32 made of a (100) oriented MgO of the NaCl-type structure was formed on a first substrate 31 by an RF magnetron sputtering apparatus. Specifically, a first substrate 31 was placed into the RF magnetron sputtering apparatus. An MgO sintered body having a fineness (purity) of 99.9% was used as a target in the RF magnetron sputtering apparatus. The RF magnetron sputtering apparatus was activated for 1 hour so that a (100) oriented MgO under layer film 32 of the NaCl-type structure was deposited on a given area (an exposed area) of the first substrate 31 by sputtering. During the sputtering, the first substrate 31 remained heated at a temperature of 600°C. Furthermore, sputtering gas composed of a mixture of argon (50%) and oxygen (50%) was used in the RF magnetron sputtering apparatus. The pressure of the sputtering gas was equal to 0.7 Pa. The RF power density in the RF magnetron sputtering apparatus was equal to 2.5 W/cm 2 . The RF power had a frequency of 13.56 MHz. The MgO under layer film 32 had a thickness of 0.2 µm. During a later stage in the fabrication of the pyroelectric infrared detector, the MgO under layer film 32 was etched off as in Example 1. The time necessary for the etching process was equal to about 75 minutes. Samples of the pyroelectric infrared detector according to Example 7 were prepared. Experiments were performed on these samples which were not subjected to a poling treatment. With respect to the samples, the productive yield was equal to 90%. The sensing portions of the samples had a pyroelectric coefficient "γ" of 3.4 × 10 -8 C/cm 2 K, a relative dielectric constant εr of 180, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the samples had a merit figure Fv (=γ/Cvεr)of 0.59 × 10 -10 Ccm/J. The relative dielectric constant of each of the samples was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the samples was represented by an average value in a temperature variation between 20-30°C. Example 8 A pyroelectric infrared detector according to Example 8 is similar to the pyroelectric infrared detector of Example 2 (see Figs. 1 and 2(a)-2(g)) except for design changes indicated hereinafter. During the fabrication of the pyroelectric infrared detector of Example 8, an oxide under layer film 32 made of a (100) oriented NiO crystal of the NaCl-type structure was formed on a first substrate 31 by an RF magnetron sputtering apparatus. Specifically, a first substrate 31 was placed into the RF magnetron sputtering apparatus. NiO powder having a fineness (purity) of 99.9% was used as a target placed in a copper dish in the RF magnetron sputtering apparatus. The RF magnetron sputtering apparatus was activated for 1.5 hours so that a (100) oriented NiO under layer film 32 of the NaCl-type structure was deposited on a given area (an exposed area) of the first substrate 31 by sputtering. During the sputtering, the first substrate 31 remained heated at a temperature of 600°C. Furthermore, sputtering gas composed of a mixture of argon (60%) and oxygen (40%) was used in the RF magnetron sputtering apparatus. The pressure of the sputtering gas was equal to 1.1 Pa. The RF power density in the RF magnetron sputtering apparatus was equal to 2.5 W/cm 2 . The RF power had a frequency of 13.56 MHz. The NiO under layer film 32 had a thickness of 0.2 µm. During a later stage in the fabrication of the pyroelectric infrared detector, the NiO under layer film 32 was etched off as in Example 2. The time necessary for the etching process was equal to about 80 minutes. Samples of the pyroelectric infrared detector according to Example 8 were prepared. Experiments were performed on these samples which were not subjected to a poling treatment. With respect to the samples, the productive yield was equal to 90%. The sensing portions of the samples had a pyroelectric coefficient "γ" of 3.3 × 10 -8 C/cm 2 K, a relative dielectric constant εr of 174, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the samples had a merit figure Fv (=γ/Cvεr)of 0.59 × 10 -10 Ccm/J. The relative dielectric constant of each of the samples was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the samples was represented by an average value in a temperature variation between 20-30°C. Example 9 A pyroelectric infrared detector according to Example 9 is similar to the pyroelectric infrared detector of Example 7 except that a substrate 37 (see Fig. 1) has a recess instead of a through hole (a through opening). Samples of the pyroelectric infrared detector according to Example 9 were prepared. Experiments were performed on these samples which were not subjected to a poling treatment. With respect to the samples, the productive yield was equal to 89%. The sensing portions of the samples had a pyroelectric coefficient "γ" of 3.4 × 10 -8 C/cm 2 K, a relative dielectric constant εr of 182, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the samples had a merit figure Fv (=γ/Cvεr)of 0.58 × 10 -10 Ccm/J. The relative dielectric constant of each of the samples was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the samples was represented by an average value in a temperature variation between 20-30°C. Example 10 A pyroelectric infrared detector according to Example 10 is similar to the pyroelectric infrared detector of Example 8 except that a substrate 37 (see Fig. 1) has a recess instead of a through hole (a through opening). Samples of the pyroelectric infrared detector according to Example 10 were prepared. Experiments were performed on these samples which were not subjected to a poling treatment. With respect to the samples, the productive yield was equal to 90%. The sensing portions of the samples had a pyroelectric coefficient "γ" of 3.2 × 10 -8 C/cm 2 K, a relative dielectric constant εr of 170, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the samples had a merit figure Fv (=γ/Cvεr)of 0.59 × 10 -10 Ccm/J. The relative dielectric constant of each of the samples was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the samples was represented by an average value in a temperature variation between 20-30°C. Example 11 A pyroelectric infrared detector according to Example 11 is similar to the pyroelectric infrared detector of Example 7 except for design changes indicated hereinafter. In the pyroelectric infrared detector of Example 11, a substrate 37 (see Fig. 1) has a recess instead of a through hole (a through opening). Furthermore, a pyroelectric film 33 (see Fig. 1) is made of PbTiO 3 as in Example 5. Samples of the pyroelectric infrared detector according to Example 11 were prepared. Experiments were performed on these samples which were not subjected to a poling treatment. With respect to the samples, the productive yield was equal to 89%. The sensing portions of the samples had a pyroelectric coefficient "γ" of 1.9 × 10 -8 C/cm 2 K, a relative dielectric constant εr of 100, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the samples had a merit figure Fv (=γ/Cvεr)of 0.59 × 10 -10 Ccm/J. The relative dielectric constant of each of the samples was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the samples was represented by an average value in a temperature variation between 20-30°C. Example 12 A pyroelectric infrared detector according to Example 12 is similar to the pyroelectric infrared detector of Example 8 except for design changes indicated hereinafter. In the pyroelectric infrared detector of Example 12, a substrate 37 (see Fig. 1) has a recess instead of a through hole (a through opening). Furthermore, a pyroelectric film 33 (see Fig. 1) is made of PbTiO 3 as in Example 6. Samples of the pyroelectric infrared detector according to Example 12 were prepared. Experiments were performed on these samples which were not subjected to a poling treatment. With respect to the samples, the productive yield was equal to 91%. The sensing portions of the samples had a pyroelectric coefficient "γ" of 1.9 × 10 -8 C/cm 2 K, a relative dielectric constant εr of 100, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the samples had a merit figure Fv (=γ/Cvεr)of 0.59 × 10 -10 Ccm/J. The relative dielectric constant of each of the samples was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the samples was represented by an average value in a temperature variation between 20-30°C. Example 13 A pyroelectric infrared detector according to Example 13 is similar to the pyroelectric infrared detector of Example 3 except for design changes indicated hereinafter. A first substrate 31 (see Figs. 2(a)-2(e)) used in the fabrication of the pyroelectric infrared detector of Example 13 was made of soda-lime glass identified by Corning #7059. A sample of the pyroelectric infrared detector according to Example 13 was prepared. Experiments were performed on the sample which was not subjected to a poling treatment. The sensing portion of the sample had a pyroelectric coefficient "γ" of 3.0 × 10 -8 C/cm 2 K, a relative dielectric constant εr of 180, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the sample had a merit figure Fv (=γ/Cvεr)of 0.52 × 10 -10 Ccm/J. The relative dielectric constant of the sample was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the sample was represented by an average value in a temperature variation between 20-30°C. Example 14 A pyroelectric infrared detector according to Example 14 is similar to the pyroelectric infrared detector of Example 13 except for design changes indicated hereinafter. During the fabrication of the pyroelectric infrared detector of Example 14, an MgO under layer film 32 (see Figs. 2(a)-2(e)) was formed by RF magnetron sputtering. A sample of the pyroelectric infrared detector according to Example 14 was prepared. Experiments were performed on the sample which was not subjected to a poling treatment. The sensing portion of the sample had a pyroelectric coefficient "γ" of 3.1 × 10 -8 C/cm 2 K, a relative dielectric constant εr of 178, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the sample had a merit figure Fv (=γ/Cvεr)of 0.54 × 10 -10 Ccm/J. The relative dielectric constant of the sample was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the sample was represented by an average value in a temperature variation between 20-30°C. Example 15 A pyroelectric infrared detector according to Example 15 is similar to the pyroelectric infrared detector of Example 13 except for design changes indicated hereinafter. During the fabrication of the pyroelectric infrared detector of Example 15, a pyroelectric film 33 (see Fig. 1) was made of PbTiO 3 by a plasma-enhanced MO-CVD process. A sample of the pyroelectric infrared detector according to Example 15 was prepared. Experiments were performed on the sample which was not subjected to a poling treatment. The sensing portion of the sample had a pyroelectric coefficient "γ" of 2.0 x 10-8 C/cm 2 K, a relative dielectric constant εr of 120, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the sample had a merit figure Fv (=γ/Cvεr) of 0.52 × 10 -10 Ccm/J. The relative dielectric constant of the sample was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the sample was represented by an average value in a temperature variation between 20-30°C. Example 16 A pyroelectric infrared detector according to Example 16 is similar to the pyroelectric infrared detector of Example 14 except for design changes indicated hereinafter. During the fabrication of the pyroelectric infrared detector of Example 16, a pyroelectric film 33 (see Fig. 1) was made of PbTiO 3 by a plasma-enhanced MO-CVD process. A sample of the pyroelectric infrared detector according to Example 16 was prepared. Experiments were performed on the sample which was not subjected to a poling treatment. The sensing portion of the sample had a pyroelectric coefficient "γ" of 1.9 × 10 -8 C/cm 2 K, a relative dielectric constant Er of 115, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the sample had a merit figure Fv (=γ/Cvεr) of 0.52 × 10 -10 Ccm/J. The relative dielectric constant of the sample was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the sample was represented by an average value in a temperature variation between 20-30°C. Example 17 A pyroelectric infrared detector according to Example 17 is similar to the pyroelectric infrared detector of Example 13 except for design changes indicated hereinafter. An oxide under layer film 32 (see Figs. 2(a)-2(e)) used in the fabrication of the pyroelectric infrared detector of Example 17 was made of NiO. A sample of the pyroelectric infrared detector according to Example 17 was prepared. Experiments were performed on the sample which was not subjected to a poling treatment. The sensing portion of the sample had a pyroelectric coefficient "γ" of 2.9 × 10 -8 C/cm 2 K, a relative dielectric constant εr of 180, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the sample had a merit figure Fv (=γ/Cvεr)of 0.50 × 10 -10 Ccm/J. The relative dielectric constant of the sample was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the sample was represented by an average value in a temperature variation between 20-30°C. Example 18 A pyroelectric infrared detector according to Example 18 is similar to the pyroelectric infrared detector of Example 14 except for design changes indicated hereinafter. An oxide under layer film 32 (see Figs. 2(a)-2(e)) used in the fabrication of the pyroelectric infrared detector of Example 18 was made of NiO. A sample of the pyroelectric infrared detector according to Example 18 was prepared. Experiments were performed on the sample which was not subjected to a poling treatment. The sensing portion of the sample had a pyroelectric coefficient "γ" of 2.8 × 10 -8 C/cm 2 K, a relative dielectric constant εr of 179, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the sample had a merit figure Fv (=γ/Cvεr)of 0.49 x 10 -10 Ccm/J. The relative dielectric constant of the sample was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the sample was represented by an average value in a temperature variation between 20-30°C. Example 19 A pyroelectric infrared detector according to Example 19 is similar to the pyroelectric infrared detector of Example 13 except for design changes indicated hereinafter. A first substrate 31 (see Figs. 2(a)-2(e)) used in the fabrication of the pyroelectric infrared detector of Example 19 was made of an Si (100) single crystal, that is, an Si single crystal exposed along a (100) plane. A sample of the pyroelectric infrared detector according to Example 19 was prepared. Experiments were performed on the sample which was not subjected to a poling treatment. The sensing portion of the sample had a pyroelectric coefficient "γ" of 3.2 × 10 -8 C/cm 2 K, a relative dielectric constant εr of 176, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the sample had a merit figure Fv (=γ/Cvεr) of 0.57 × 10 -10 Ccm/J. The relative dielectric constant of the sample was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the sample was represented by an average value in a temperature variation between 20-30°C. Example 20 A pyroelectric infrared detector according to Example 20 is similar to the pyroelectric infrared detector of Example 14 except for design changes indicated hereinafter. A first substrate 31 (see Figs. 2(a)-2(e)) used in the fabrication of the pyroelectric infrared detector of Example 20 was made of an Si (100) single crystal. that is, an Si single crystal exposed along a (100) plane. A sample of the pyroelectric infrared detector according to Example 20 was prepared. Experiments were performed on the sample which was not subjected to a poling treatment. The sensing portion of the sample had a pyroelectric coefficient "γ" of 3.2 × 10 -8 C/cm 2 K, a relative dielectric constant εr of 177, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the sample had a merit figure Fv (=γ/Cvεr)of 0.56 × 10 -10 Ccm/J. The relative dielectric constant of the sample was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the sample was represented by an average value in a temperature variation between 20-30°C. Example 21 A pyroelectric infrared detector according to Example 21 is similar to the pyroelectric infrared detector of Example 17 except for design changes indicated hereinafter. A first substrate 31 (see Figs. 2(a)-2(e)) used in the fabrication of the pyroelectric infrared detector of Example 21 was made of an Si (100) single crystal, that is, an Si single crystal exposed along a (100) plane. A sample of the pyroelectric infrared detector according to Example 21 was prepared. Experiments were performed on the sample which was not subjected to a poling treatment. The sensing portion of the sample had a pyroelectric coefficient "γ" of 3.1 × 10 -8 C/cm 2 K, a relative dielectric constant εr of 180, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the sample had a merit figure Fv (=γ/Cvεr)of 0.54 × 10 -10 Ccm/J. The relative dielectric constant of the sample was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the sample was represented by an average value in a temperature variation between 20-30°C. Example 22 A pyroelectric infrared detector according to Example 22 is similar to the pyroelectric infrared detector of Example 18 except for design changes indicated hereinafter. A first substrate 31 (see Figs. 2(a)-2(e)) used in the fabrication of the pyroelectric infrared detector of Example 22 made of an Si (100) single crystal, that is, an Si single crystal exposed along a (100) plane. A sample of the pyroelectric infrared detector according to Example 22 was prepared. Experiments were performed on the sample which was not subjected to a poling treatment. The sensing portion of the sample had a pyroelectric coefficient "γ" of 3.2 × 10 -8 C/cm 2 K, a relative dielectric constant εr of 178, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the sample had a merit figure Fv (=γ/Cvεr)of 0.56 × 10 -10 Ccm/J. The relative dielectric constant of the sample was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the sample was represented by an average value in a temperature variation between 20-30°C. Example 23 A pyroelectric infrared detector according to Example 23 is similar to the pyroelectric infrared detector of Example 13 except for design changes indicated hereinafter. A first substrate 31 (see Figs. 2(a)-2(e)) used in the fabrication of the pyroelectric infrared detector of Example 23 was made of an Si (111) single crystal, that is, an Si single crystal exposed along a (111) plane. A sample of the pyroelectric infrared detector according to Example 23 was prepared. Experiments were performed on the sample which was not subjected to a poling treatment. The sensing portion of the sample had a pyroelectric coefficient "γ" of 3.2 × 10 -8 C/cm 2 K, a relative dielectric constant εr of 178, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the sample had a merit figure Fv (=γ/Cvεr)of 0.56 × 10 -10 Ccm/J. The relative dielectric constant of the sample was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the sample was represented by an average value in a temperature variation between 20-30°C. Example 24 A pyroelectric infrared detector according to Example 24 is similar to the pyroelectric infrared detector of Example 14 except for design changes indicated hereinafter. A first substrate 31 (see Figs. 2(a)-2(e)) used in the fabrication of the pyroelectric infrared detector of Example 24 was made of an Si (111) single crystal, that is, an Si single crystal exposed along a (111) plane. A sample of the pyroelectric infrared detector according to Example 24 was prepared. Experiments were performed on the sample which was not subjected to a poling treatment. The sensing portion of the sample had a pyroelectric coefficient "γ" of 3.2 × 10 -8 C/cm 2 K, a relative dielectric constant εr of 178, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the sample had a merit figure Fv (=γ/Cvεr)of 0.56 × 10 -10 Ccm/J. The relative dielectric constant of the sample was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the sample was represented by an average value in a temperature variation between 20-30°C. Example 25 A pyroelectric infrared detector according to Example 25 is similar to the pyroelectric infrared detector of Example 17 except for design changes indicated hereinafter. A first substrate 31 (see Figs. 2(a)-2(e)) used in the fabrication of the pyroelectric infrared detector of Example 25 was made of an Si (111) single crystal, that is, an Si single crystal exposed along a (111) plane. A sample of the pyroelectric infrared detector according to Example 25 was prepared. Experiments were performed on the sample which was not subjected to a poling treatment. The sensing portion of the sample had a pyroelectric coefficient "γ" of 3.1 x 10 -8 C/cm 2 K, a relative dielectric constant εr of 180, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the sample had a merit figure F/v (=γ/Cvεr) of 0.54 x 10 -10 Ccm/J. The relative dielectric constant of the sample was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the sample was represented by an average value in a temperature variation between 20-30°C. Example 26 A pyroelectric infrared detector according to Example 26 is similar to the pyroelectric infrared detector of Example 18 except for design changes indicated hereinafter. A first substrate 31 (see Figs. 2(a)-2(e)) used in the fabrication of the pyroelectric infrared detector of Example 26 was made of an Si (111) single crystal, that is, an Si single crystal exposed along a (111) plane. A sample of the pyroelectric infrared detector according to Example 26 was prepared. Experiments were performed on the sample which was not subjected to a poling treatment. The sensing portion of the sample had a pyroelectric coefficient "γ" of 3.1 × 10 -8 C/cm 2 K, a relative dielectric constant εr of 180, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the sample had a merit figure Fv (=γ/Cvεr)of 0.54 x 10 -10 Ccm/J. The relative dielectric constant of the sample was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the sample was represented by an average value in a temperature variation between 20-30°C. Example 27 A pyroelectric infrared detector according to Example 27 is similar to the pyroelectric infrared detector of Example 13 except for design changes indicated hereinafter. A first substrate 31 (see Figs. 2(a)-2(e)) used in the fabrication of the pyroelectric infrared detector of Example 27 was made of a sintered alumina body. A sample of the pyroelectric infrared detector according to Example 27 was prepared. Experiments were performed on the sample which was not subjected to a poling treatment. The sensing portion of the sample had a pyroelectric coefficient "γ" of 3.1 × 10 -8 C/cm 2 K, a relative dielectric constant εr of 180, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the sample had a merit figure Fv (=γ/Cvεr)of 0.54 × 10 -10 Ccm/J. The relative dielectric constant of the sample was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the sample was represented by an average value in a temperature variation between 20-30°C. Example 28 A pyroelectric infrared detector according to Example 28 is similar to the pyroelectric infrared detector of Example 14 except for design changes indicated hereinafter. A first substrate 31 (see Figs. 2(a)-2(e)) used in the fabrication of the pyroelectric infrared detector of Example 28 was made of a sintered alumina body. A sample of the pyroelectric infrared detector according to Example 28 was prepared. Experiments were performed on the sample which was not subjected to a poling treatment. The sensing portion of the sample had a pyroelectric coefficient "γ" of 3.0 × 10 -8 C/cm 2 K, a relative dielectric constant εr of 178, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the sample had a merit figure Fv (=γ/Cvεr)of 0.53 × 10 -10 Ccm/J. The relative dielectric constant of the sample was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the sample was represented by an average value in a temperature variation between 20-30°C. Example 29 A pyroelectric infrared detector according to Example 29 is similar to the pyroelectric infrared detector of Example 17 except for design changes indicated hereinafter. A first substrate 31 (see Figs. 2(a)-2(e)) used in the fabrication of the pyroelectric infrared detector of Example 29 was made of a sintered alumina body. A sample of the pyroelectric infrared detector according to Example 29 was prepared. Experiments were performed on the sample which was not subjected to a poling treatment. The sensing portion of the sample had a pyroelectric coefficient "γ" of 2.9 x 10 -8 C/cm 2 K, a relative dielectric constant εr of 178, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the sample had a merit figure Fv (=γ/Cvεr)of 0.51 × 10 -10 Ccm/J. The relative dielectric constant of the sample was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the sample was represented by an average value in a temperature variation between 20-30°C. Example 30 A pyroelectric infrared detector according to Example 30 is similar to the pyroelectric infrared detector of Example 18 except for design changes indicated hereinafter. A first substrate 31 (see Figs. 2(a)-2(e)) used in the fabrication of the pyroelectric infrared detector of Example 30 was made of a sintered alumina body. A sample of the pyroelectric infrared detector according to Example 30 was prepared. Experiments were performed on the sample which was not subjected to a poling treatment. The sensing portion of the sample had a pyroelectric coefficient "γ" of 2.9 x 10 -8 C/cm 2 K, a relative dielectric constant εr of 178, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the sample had a merit figure Fv (=γ/Cvεr)of 0.51 x 10 -10 Ccm/J. The relative dielectric constant of the sample was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the sample was represented by an average value in a temperature variation between 20-30°C. Example 31 A pyroelectric infrared detector according to Example 31 is similar to the pyroelectric infrared detector of Example 29 except for design changes indicated hereinafter. During the fabrication of the pyroelectric infrared detector of Example 31, a pyroelectric film 33 (see Fig. 1) was made of PbTiO3 by a plasma-enhanced MO-CVD process. A sample of the pyroelectric infrared detector according to Example 31 was prepared. Experiments were performed on the sample which was not subjected to a poling treatment. The sensing portion of the sample had a pyroelectric coefficient "γ" of 2.0 x 10 -8 C/cm 2 K, a relative dielectric constant εr of 120, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the sample had a merit figure Fv (=γ/Cvεr) of 0.52 x 10 -10 Ccm/J. The relative dielectric constant of the sample was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the sample was represented by an average value in a temperature variation between 20-30°C. Example 32 A pyroelectric infrared detector according to Example 32 is similar to the pyroelectric infrared detector of Example 30 except for design changes indicated hereinafter. During the fabrication of the pyroelectric infrared detector of Example 32, a pyroelectric film 33 (see Fig. 1) was made of PbTiO 3 by a plasma-enhanced MO-CVD process. A sample of the pyroelectric infrared detector according to Example 32 was prepared. Experiments were performed on the sample which was not subjected to a poling treatment. The sensing portion of the sample had a pyroelectric coefficient "γ" of 1.9 x 10 -8 C/cm 2 K, a relative dielectric constant εr of 122, and a volume specific heat Cv of 3.2 Jcm 3 K. Thus, the sample had a merit figure Fv (=γ/Cvεr) of 0.49 x 10 -10 Ccm/J. The relative dielectric constant of the sample was measured by using an LCR meter with a frequency of 1 kHz and an applied voltage of 1 V. The pyroelectric coefficient of the sample was represented by an average value in a temperature variation between 20-30°C.

Claims: A method of fabricating a pyroelectric infrared detector, comprising the steps of: forming an under layer film (32) of oriented oxide on a first substrate (31); forming a pyroelectric portion (33) on a given area of a surface of the under layer film; forming a resin film (35) covering the pyroelectric portion (33) and an exposed area of the surface of the under layer film (32); bonding a second substrate (37) to the resin film (35); and etching off the under layer film (32) to remove the first substrate (31) from the pyroelectric portion (33) and the resin film (35). The method of claim 1, wherein the under-layer-film forming step comprises depositing the under layer film on the first substrate by a plasma-enhanced MO-CVD process, and using a vapor of an organometallic complex as a source gas. The method of claim 1, wherein the under-layer-film forming step comprises depositing the under layer film on the first substrate by a sputtering process. The method of claim 1, wherein the under layer film is made of a material which allows the pyroelectric portion to be oriented in a direction of polarization, and which can be easily etched off. The method of claim 1, wherein the under layer film has a crystal structure of an NaCl type. The method of claim 1, wherein the under layer film is made of MgO. The method of claim 1, wherein the under layer film is made of NiO.

Inventors: FUJII SATORU, OKANO MASAYUKI, TAKAYAMA RYOICHI, TOMITA YOSHIHIRO, TORII HIDEO, FUJII, SATORU, OKANO, MASAYUKI, TAKAYAMA, RYOICHI, TOMITA, YOSHIHIRO, TORII, HIDEO
Applicants: MATSUSHITA ELECTRIC IND CO LTD, MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.
Application year: 1993
Main classification: H01L37
IPC codes: H01L37, G01J5, G01J1