JP5079211B2 - Infrared detector and manufacturing method thereof - Google Patents

Description

   The present invention relates to an infrared detection device and a method for manufacturing the same.

  Infrared detectors have been used as thermometers and analyzers, and have been used for human body detection. As this infrared detection device, one having an infrared detection unit that detects infrared rays by converting them into heat is known. In such an infrared detector, since the infrared detector is mounted on the oxide film laminated on the semiconductor substrate, the semiconductor directly under the infrared detector is used to reduce heat conduction from the infrared detector to the semiconductor substrate. A so-called membrane structure in which a cavity is provided in the substrate is employed.

In such a membrane structure, the cavity is generally formed by isotropic etching, but etching proceeds at approximately the same speed in the stacking direction of the substrate and the oxide film and in the direction (plane direction) perpendicular thereto, If the cavity is deepened to increase the heat insulation effect, the etching in the plane direction will also spread. Therefore, in order to suppress the spread of etching in the planar direction, a trench is formed in the semiconductor substrate, a silicon oxide film is embedded in the trench, an etching stopper is formed, and the inside of the etching stopper is etched. There is a technique for forming a cavity (see, for example, Patent Document 1).
JP 2002-299596 A

  However, with the technique described in Patent Document 1, the size of the cavity in the direction orthogonal to the stacking direction is defined, but it is difficult to control the depth of the cavity. And if the depth of the cavity changes and its shape and size change, the amount of heat dissipated will change accordingly, so uniform detection sensitivity cannot be obtained in multi-elements, and single elements have the same lot. In this case, uniform detection sensitivity cannot be obtained between elements.

  Therefore, the present invention can easily obtain uniform detection sensitivity in a multi-element configuration, and can easily obtain uniform detection sensitivity between elements in the same lot in a single element, and a method for manufacturing the same. The purpose is to provide.

  In order to solve the above problems, an infrared device according to the present invention is an infrared detection device having an infrared detection unit, and includes a first semiconductor layer and a first insulator stacked on the first semiconductor layer. A second semiconductor layer formed on the first insulator layer and formed with a cavity portion penetrating along the lamination direction; an insulating film formed on the inner wall surface of the cavity portion; And a second insulator layer that is stacked on the semiconductor layer and supports the infrared detection unit so as to face the cavity in the stacking direction.

  The cavity is partitioned from the first semiconductor layer and the second semiconductor layer by the first insulator layer and the insulating film. The first insulator layer and the insulating film function as an etching stopper when the cavity is formed by etching the second semiconductor layer laminated on the first insulator layer. As a result, the shape and size of the cavity formed by etching is surely defined by the first insulator layer and the insulating film, so the second insulator layer disposed at a position facing the cavity. With the upper infrared detection unit, uniform detection sensitivity can be obtained in multi-elements, and with a single element, uniform detection sensitivity can be obtained between elements in the same lot.

  In the infrared detection device according to the present invention, it is preferable that the first insulator layer and the second insulator layer are substantially parallel at least in the cavity. In this case, since the first insulator layer and the second insulator layer are substantially parallel, the infrared rays transmitted through the second insulator layer are reflected at substantially the same angle by the first insulator layer. . Thereby, since the reflected infrared rays are uniformly detected by the infrared detection unit, the uniformity of the detection sensitivity within the infrared detection device is improved.

  Furthermore, the thermal conductivity of the first insulator layer, the second insulator layer, and the insulating film in the infrared detection device according to the present invention is smaller than the thermal conductivity of the first semiconductor layer and the second semiconductor layer. Is preferred. In this case, since the amount of heat dissipation from the cavity to the first and second semiconductor layers is reduced, the detection sensitivity tends to be improved.

  Moreover, in the infrared detecting device according to the present invention, the first insulating layer and the second insulating layer are provided between the cavities facing each of the infrared detecting units in the stacking direction. Are preferably substantially equal to each other. In this case, since the distance between the first and second insulator layers in the cavity facing each of the plurality of infrared detection units is the same, the uniformity of detection sensitivity for each infrared detection unit is improved.

  Moreover, the manufacturing method of the infrared rays detection apparatus which concerns on this invention is a manufacturing method of the infrared rays detection apparatus which has an infrared detection part, Comprising: The 1st insulator laminated | stacked on the 1st semiconductor layer and the 1st semiconductor layer And a step of preparing a stacked body having a second semiconductor layer stacked on the first insulator layer, and a step of forming an insulating film on an outer periphery of a predetermined portion in the second semiconductor layer; A step of laminating a second insulator layer on the second semiconductor layer, and a step of forming an infrared detector on the second insulator layer so as to face a predetermined portion in the laminating direction; And a step of removing a predetermined portion from the second semiconductor layer by etching to form a cavity partitioned by the first insulator layer, the second insulator layer, and the insulating film. .

  In this manufacturing method, when a predetermined portion is removed by etching to form a cavity, the insulating film formed in the second semiconductor layer included in the stacked body functions as an etching stopper in a direction orthogonal to the stacking direction. The first insulator layer included in the stacked body functions as an etching stopper in the stacking direction. Therefore, the shape and size of the cavity are reliably controlled by the insulating film and the first insulator layer. As a result, the infrared detection apparatus to be manufactured can obtain uniform detection sensitivity when the number of elements is increased, and with a single element, uniform detection sensitivity can be obtained between elements in the same lot.

  Further, in the method of manufacturing the infrared detection device according to the present invention, after forming the trench on the outer periphery of the predetermined portion, the insulating material is filled in the trench to form an insulating film, or on the outer periphery of the predetermined portion. After forming the trench, it is preferable to oxidize the semiconductor layer to form an insulating film. In this case, the cavity can be reliably partitioned by the insulating film. The insulating film is not limited to the insulating film formed by oxidation, and may be formed by CVD or the like.

  According to the infrared detection device of the present invention, it is possible to obtain uniform detection sensitivity in the case of multi-elements for detecting infrared rays, and it is possible to obtain uniform detection sensitivity between elements in the same lot with a single element. . In addition, according to the method for manufacturing an infrared detection device of the present invention, an infrared detection device having uniform detection sensitivity in the case of multi-elements and having uniform detection sensitivity between elements in the same lot in a single element is manufactured. be able to.

  Hereinafter, preferred embodiments of an infrared detection device and a manufacturing method thereof according to the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a plan view of an embodiment of an infrared detection device according to the present invention. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. The infrared detection device 10 shown in FIGS. 1 and 2 is a thermal infrared detection device that detects infrared rays by converting them into heat, and is used, for example, as a radiation thermometer.

As shown in FIG. 2, the infrared detecting device 10 includes a silicon substrate (first semiconductor layer) 12, and an insulator layer (SiO ₂ ) having a substantially constant thickness on the silicon substrate 12. First insulator layer) 14 is laminated. A silicon layer (second semiconductor layer) 16 is further laminated on the insulator layer 14 with a constant thickness to realize an SOI (Silicon on Insulator) structure.

The silicon layer 16 forming a part of the SOI structure has a box-shaped cavity 18 penetrating along the stacking direction, and an insulating film 20 made of SiO ₂ is formed on the inner wall surface 18a of the cavity 18. . The cavity 18 is formed by etching the silicon layer 16 partitioned by the insulating film 20, and its shape and size are defined by the insulating film 20 and the insulator layer 14. The box shape may be a square shape or a cylindrical shape.

An insulating layer (second insulating layer) 22 made of SiO ₂ is laminated on the silicon layer 16 having the cavity 18 substantially in parallel with the insulating layer 14 to realize a membrane structure. An infrared detection unit 24 that detects infrared rays is provided on the insulator layer 22. The infrared detection unit 24 is disposed at a position facing the cavity 18 in the stacking direction, and an infrared absorption film 26 that absorbs infrared rays, and a thermopile 28 as a temperature detection unit that detects a temperature change of the infrared absorption film 26. It consists of. In addition, as a temperature detection part, a bolometer etc. may be sufficient other than a thermopile, for example.

  As shown in FIG. 1, the thermopile 28 is a thermoelectric device in which end portions of an n-type polysilicon film 30 and a p-type polysilicon film 32 arranged in parallel on the insulator layer 22 are connected by an aluminum film 34. A plurality of pairs are connected in series. The polysilicon films 30 and 32 constituting the thermocouple are arranged from above the silicon layer 16 to above the cavity 18 and are perpendicular to the four sides of the cavity 18 formed in a rectangular shape. It is arrange | positioned so that it may extend toward the center of the cavity part 18 from.

The exposed surfaces of the polysilicon films 30 and 32 and the insulator layer 22 are covered with an insulator layer 36 made of, for example, SiO ₂ as shown in FIG. An aluminum film 34 that connects the end portions of the polysilicon films 30 and 32 is disposed on the insulator layer 36, and the aluminum film 34 is formed on the end portions of the polysilicon films 30 and 32. The polysilicon films 30 and 32 are electrically connected through the 36 opening holes. The exposed surface of the aluminum film 34 and the insulator layer 36 are covered with a passivation layer 38 made of SiN. The insulator layer 36 and the passivation layer 38 may be not only SiO ₂ and SiN but also an insulator layer made of SiON, PSG, BPSG, polyimide, or a laminated film thereof.

A rectangular infrared absorption film 26 that absorbs infrared rays is provided on the passivation layer 38 and above the cavity 18. The infrared absorption film 26 is made of a black resin having a high infrared absorption rate, and the black resin is a resin in which a black filler such as a carbon filler is mixed (epoxy, silicone, acrylic, urethane, polyimide, or the like) Composite resins), black resists, etc., gold black, TiN, NiCr, PSG, BPSG, SiN, SiON, SiO ₂ , polysilicon, amorphous silicon and other inorganic materials, or these composite films. May be.

  In the above configuration, of the connection portions of the polysilicon films 30 and 32 constituting the thermopile 28, the connection portion located above the cavity portion 18 and directly below the infrared absorption film 26 functions as a hot junction, and the silicon layer The connection part located above 16 functions as a cold junction. And the thermoelectromotive force which generate | occur | produces between a warm junction and a cold junction by the temperature change of the infrared rays absorption film 26 is taken out by a pair of extraction electrodes 40 and 42 (refer FIG. 1). In the region where the extraction electrodes 40 and 42 are formed, the passivation layer 38 is open.

The infrared detection device 10 is manufactured, for example, as follows. That is, as shown in FIG. 3A, first, an SOI substrate 44 is prepared as a stacked body in which an insulator layer 14 and a silicon layer 16 are stacked in this order on a silicon substrate 12. Next, insulation is performed from the upper surface of the silicon layer 16 on the outer periphery of a predetermined portion 46 of the silicon layer 16 (portion to be the cavity 18), that is, on the boundary between the predetermined portion 46 of the silicon layer 16 and other portions. A trench (i.e., groove) 48 extending to the body layer 14 is formed. Subsequently, as shown in FIG. 3B, after the insulating film 20 is formed by filling the trench 48 with SiO ₂ as an insulating material by CVD (Chemical Vapor Deposition) method or thermal oxidation, a silicon layer is formed. An insulator layer 22 is laminated on the top 16.

  Then, as shown in FIG. 4, the thermopile 28 is formed on the insulator layer 22 at a position facing the predetermined portion 46. At this time, an insulator layer 36 covering the exposed portions of the polysilicon films 30 and 32 and a passivation layer 38 covering the exposed portions of the aluminum film 34 are also formed in accordance with the formation of the thermopile 28. Next, after forming an etching hole 50 penetrating the passivation layer 38, the insulating film 20, and the insulator layer 14 in the stacking direction, the infrared absorption film 26 is formed on the passivation layer 38 and above the predetermined portion 46. To do. As a result, the infrared absorbing portion 24 on the insulator layer 22 and facing the predetermined portion 46 is obtained. Note that the etching hole 50 may be formed after the infrared absorption film 26 is formed. Further, when the infrared absorption film 26 is formed, a through hole 52 is formed at a position corresponding to the etching hole 50.

Thereafter, XeF ₂ gas enters through the through hole 52 and the etching hole 50 of the infrared absorption film 26, whereby the predetermined portion 46 of the silicon layer 16 is removed by dry etching. Thereby, the cavity 18 is formed to form a membrane structure. At this time, since the insulating film 20 and the insulator layer 14 function as an etching stopper, the shape and size of the cavity 18 are reliably defined. Further, since dry etching is used, damage to the infrared absorption film 26 due to etching is suppressed as compared with wet etching.

An etching gas for dry etching the cavity 18 is not particularly limited as long as silicon can be dry etched. For example, addition of _{XeF 2, XeF 4, XeF 6} , KrF 2, KrF 4, KrF 6, ClF 3, BrF 3, BrF 5, IF 5, SF 6, CF 4 can be utilized. In the above process, the predetermined portion 46 of the silicon layer 16 is etched after the infrared absorption film 26 is formed. However, the infrared absorption film 26 is formed after the etching to form the cavity 18 first. Is also possible.

  FIG. 5A is a plan view of the SOI substrate 44 in a state where the cavity 18 is formed in the above-described process. FIG. 5B is a partially enlarged view of FIG. FIG. 6 is a cross-sectional view taken along the line VI-VI in FIG. In FIG. 6, the extraction electrode and the wiring from each pixel are omitted.

  As shown in FIGS. 5 and 6, a plurality of infrared detection units 24 are formed on one SOI substrate 44, and a cavity 18 is formed immediately below each infrared detection unit 24. That is, since the SOI substrate 44 in this state is obtained by integrating a plurality of infrared detection devices 10, a virtual dicing line (one-dot chain line in FIGS. 5 and 6) L between the infrared detection units 24. The individual infrared detection devices 10 can be obtained by cutting the SOI substrate 44 along.

  In the infrared detecting device 10 shown in FIGS. 1 and 2 manufactured as described above, the thermopile 28 detects a temperature change of the infrared absorbing film 26 generated by the infrared absorbing film 26 absorbing infrared rays. Infrared is detected with.

  The infrared detection device 10 has the cavity 18 immediately below the infrared absorption film 26 from the viewpoint of suppressing the heat dissipation of the infrared absorption film 26 and improving the detection sensitivity, but the amount of heat dissipation depends on the shape of the cavity 18. It depends on the size. Therefore, it is important to control the shape and size of the cavity 18 in order to make the detection sensitivity uniform among the elements in the same lot of a single element in the infrared detection device 10.

  In the above manufacturing method, when the cavity 18 is formed by dry etching, the insulator layer 14 functions as an etching stopper in the depth direction (stacking direction), and the insulating film 20 is in the planar direction (direction orthogonal to the stacking direction). Since the shape and size of the cavity 18 can be controlled, the infrared detection device 10 can reliably obtain uniform detection sensitivity between elements in the same lot of a single element.

Further, the box-shaped cavity 18 is surrounded by SiO ₂ (thermal conductivity: about 1.3 W / m / K) having a lower thermal conductivity than silicon (thermal conductivity: about 125 W / m / K). Since the cavity 18 is partitioned from the silicon substrate 12 and the silicon layer 16, heat dissipation is suppressed and the heat insulating effect is enhanced. As a result, the detection sensitivity of the infrared absorber 24 is improved. Since the cavity 18 is partitioned by the insulator layer 14, the insulating film 20, and the insulator layer 22, the heat insulating effect is enhanced as described above, and thus the depth of the cavity 18 can be reduced. . As a result, the time required for the formation process of the cavity 18 is shortened and the manufacturing efficiency tends to be improved.

Furthermore, since the cavity 18 is surrounded by the same material (SiO ₂ ), the bending due to thermal expansion at the time of infrared detection is reduced, and the shape of the cavity 18 is less likely to be deformed. Variations in detection sensitivity within a lot tend to decrease.

  Further, as described above, since the thicknesses of the insulator layer 14 and the silicon layer 16 are substantially constant, the insulator layer 22 and the insulator layer 14 on the silicon layer 16 are substantially parallel, and the cavity 18 The insulator layer 14 that forms the bottom of the substrate is also flat. Thus, when the infrared light transmitted through the insulating layer 22 is reflected by the insulating layer 14, the infrared light is reflected at substantially the same angle. For this reason, since the reflected infrared rays are irradiated and absorbed by the infrared absorption film 26 almost uniformly, there is little error due to the arrangement of the polysilicon films 30 and 32, and a single element has a uniform detection sensitivity between elements in the same lot. Easy to get.

  Further, as shown in the above manufacturing method, when a plurality of infrared detection devices 10 are manufactured from one SOI substrate 44, the shape and size of the cavity 18 included in each infrared detection device 10 are uniform. In particular, since the thicknesses of the insulator layer 14 and the silicon layer 16 are substantially constant in the SOI substrate 44, the depth d of the cavity 18 is substantially uniform between the cavities 18 as shown in FIG. Thereby, the infrared detecting device 10 with uniform detection sensitivity can be manufactured, and the manufacturing yield is improved.

  Next, a modification of the infrared detection device 10 will be described with reference to FIGS. 7 and 8. 7 is a plan view of the infrared detecting device 54, and FIG. 8 is a cross-sectional view taken along the line VIII-VIII in FIG.

As shown in FIGS. 7 and 8, the infrared detecting device 54 is configured such that an insulating film 56 made of SiO ₂ is further formed inside the insulating film 20, and the cavity 18 has the first cavity 18 </ b> A and the second cavity 18 </ b> A. The configuration is different from the configuration of the infrared detection device 10 in that it is partitioned by the hollow portion 18B.

  The infrared detection device 54 is manufactured as follows. That is, when the trench 48 is formed in the silicon layer 16, the trench 48 is also formed in a portion corresponding to the outer periphery of the first cavity 18 </ b> A, and the subsequent steps are the same as the manufacturing method of the infrared detection device 10. Thus, the infrared detection device 54 can be manufactured.

In the infrared detection device 54, the insulating film 56 functions as a support, so that the mechanical strength of the infrared detection device 10 is improved. Since the insulating film 56 is provided, the shapes of the first and second cavities 18A and 18B are unlikely to change, and thus the detection sensitivity tends to be stable in the long term. It should be noted that the effect that the depth d of the first and second cavities 18A and 18B is substantially constant, and SiO _{2 in} which the first and second cavities 18A and 18B have lower thermal conductivity than silicon. The effect of being surrounded by is the same as that of the infrared detecting device 10.

(Second Embodiment)
The infrared detection device of the second embodiment will be described using FIG. The same elements as those of the infrared detection apparatus 10 of the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 9 is a plan view of the infrared detecting device 58 of the second embodiment. FIG. 10 is a cross-sectional view taken along line XX in FIG. Note that in FIG. 9 and FIG. 10, extraction electrodes, wiring from each pixel, and the like are omitted.

  The infrared detector 58 is an array type infrared detector 58 in which 16 infrared detectors 24 are arranged in a 4 × 4 array, and the infrared detector 10 in FIG. This corresponds to a pixel 60 arranged in an array. In the infrared detection device 58, one of the extraction electrodes 40 and 42 (see FIG. 1) included in each pixel 60, for example, the extraction electrode 42 is connected to a common electrode (not shown) provided in the infrared detection device 58. Infrared detection can be performed two-dimensionally, so it is used for an infrared image sensor.

  In the infrared detection device 58, as shown in FIG. 10, since the cavity 18 is formed immediately below each infrared detection unit 24, each infrared detection unit 24 has the same reason as the infrared detection device 10. The detection sensitivity can be made uniform among the elements of the array, and the detection sensitivity of each array element in the same lot can also be made uniform. And since the depth d of each cavity part 18 is substantially the same, the uniformity of the detection sensitivity of each infrared detection part 24 is high, and infrared rays can be detected with high accuracy.

  The infrared detecting device 58 is manufactured as follows, for example. That is, as in the case of the first embodiment, in the prepared SOI substrate 44, after the insulating film 20 is formed on the outer periphery of the predetermined portion 46 that becomes each cavity 18 of the silicon layer 16, the insulating film 20 is formed on the silicon layer 16. The insulator layer 22 is laminated. And after forming the infrared detection part 24 on the insulator layer 22 of the position facing each predetermined part 46, the silicon layer 16 (namely, predetermined part 46) just under it is removed by dry etching, and each A cavity 18 is formed. Thereafter, for example, 16 infrared detectors 24 arranged in 4 × 4 are set as one set, and each set is diced to obtain individual infrared detection devices 58.

  In the manufacturing method of the infrared detecting device 58, since the etching region in the plane direction is reliably defined by the insulating film 20 when the cavity portion 18 is formed, the infrared detecting portions 24 can be arranged with high density. It is possible to reduce the size of the two-dimensional array type infrared detector 58. In addition, since the SOI substrate 44 is used, the depth d between the cavities 18 corresponding to the infrared detection units 24 is substantially the same as in the case of the first embodiment. An infrared detection device 58 with uniform detection sensitivity can be easily manufactured.

  FIG. 11 is a plan view showing a modification of the infrared detecting device 58. 12 is a cross-sectional view taken along line XII-XII in FIG. FIG. 12 is an enlarged view of a part of the cross section. In FIGS. 11 and 12, the description of the extraction electrode and the wiring is omitted.

  The infrared detection device 62 shown in FIG. 11 is different from the infrared detection device 58 in that each of the infrared detection units 24 has an FET (Field-Effect Transistor) 64 as a signal processing circuit at an adjacent position. As shown in FIG. 12, the FET 64 is formed in the silicon layer 16 outside the cavity 18, and the source 66, the gate 68, and the drain 70 of the FET 64 are covered with the passivation layer 38.

  The infrared detecting device 62 is a cavity formed after the insulating film 20 is formed and the insulating layer 22, the thermopile 28, the insulating layer 36, and the like are formed in the manufacturing process of the infrared detecting device 58 shown in FIG. The FET 64 is manufactured outside the predetermined portion 46 to be the portion 18. Also in this manufacturing method, among the sizes of the cavity portion 18, the size in the planar direction in particular is reliably defined by the insulating film 20. As a result, even if the FET 64 is formed so as to be adjacent to the infrared detection unit 24, the silicon layer 16 in the region of the FET 64 is not etched away, so that the infrared detection device 62 having the FET 64 can be reliably manufactured. Since the FET 64 is included in the infrared detector 62, signal processing and the like can be performed quickly.

(Third embodiment)
A method of manufacturing the infrared detection device of the third embodiment will be described with reference to FIG. The same elements as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

FIG. 13 is a process diagram of the manufacturing method of the infrared detecting device of the third embodiment. In this method, as shown in FIG. 13A, as in the case of the first embodiment, after the SOI substrate 44 is prepared, a trench 48 is formed on the outer periphery (boundary) of a predetermined portion 46. . Next, the silicon layer 16 is oxidized to form an insulating film 20 made of SiO _{2 on} the surface of the silicon layer 16. Thereafter, as shown in FIG. 13B, after filling the trench 72 with polysilicon 72 as a filler, as shown in FIG. 13C, an insulator layer (second layer) is formed on the silicon layer 16. An insulating layer 74 is formed and planarized. As the insulator layer 74, PSG (Phosphosilicate Glass) having reflow characteristics is suitable for facilitating flattening. Note that the filling material for filling the trench 48 is not limited to the polysilicon 72 and is not particularly limited as long as it has heat resistance to a high-temperature process.

Next, in the same manner as in the first embodiment, after the infrared detector 24 is formed on the insulator layer 74 facing the predetermined portion 46, XeF ₂ gas enters through the etching hole 50, whereby the silicon layer 16 has a predetermined shape. The portion 46 is removed by dry etching. As a result, a cavity 18 is formed in the silicon layer 16 below the infrared detection unit 24. Then, the infrared detector 76 shown in FIG. 14 is obtained by separating into individual infrared detectors along the dicing line L between the infrared detectors 24.

In the infrared detecting device 76 shown in FIG. 14 manufactured as described above, since the silicon layer 16 is oxidized after the trench 48 is formed, the width w (see FIG. 13) in the planar direction of the trench 48 is long. In addition, a predetermined portion 46 to be the cavity 18 is covered with a silicon oxide film. As a result, since SiO ₂ is reliably formed on the inner wall surface of the cavity 18, the heat insulation effect is increased and the detection sensitivity tends to be improved as in the first embodiment. Further, in the infrared detecting device 76, since the cavity 18 is surrounded by the partition wall 78 made of the polysilicon 72 and the SiO ₂ film sandwiching the polysilicon 72, bending due to thermal expansion or the like is further suppressed. Thereby, since the shape of the cavity part 18 is stabilized, it exists in the tendency which can obtain the detection sensitivity stabilized in the long term.

  FIG. 15 is a cross-sectional view showing a modified form of the infrared detecting device 76. The infrared detection device 80 shown in FIG. 15 is different from the infrared detection device 76 in that a partition wall 82 made of polysilicon 72 and the insulating film 20 sandwiching the polysilicon 72 is further provided inside the partition wall 78. In this case, similarly to the infrared detection device 54 shown in FIG. 7, the partition wall 82 functions as a support, so that the mechanical strength of the infrared detection device 80 is improved. In addition, as a result of the shape of the cavity 18 hardly changing, there is a tendency that a long-term stable detection sensitivity can be realized.

  As mentioned above, although preferred embodiment was described for this invention, it cannot be overemphasized that this invention is not limited to the said embodiment. For example, although the silicon substrate 12 is used as the first semiconductor layer, it may be a semiconductor layer provided between the insulator layer 14 and the substrate. The insulator layer 22 as the second insulator layer has a single-layer structure, but a plurality of layers may be laminated.

In addition, silicon is exemplified as the material of the first and second semiconductor layers, and SiO ₂ is exemplified as the material of the first and second insulator layers and the insulating film. However, silicon and SiO ₂ are not necessarily described. Not limited to. However, the thermal conductivity of the first and second insulator layers and the insulating film is preferably smaller than that of the first and second semiconductor layers from the viewpoint of improving detection sensitivity.

  Moreover, in the manufacturing method of the infrared detection device, an SOI substrate is used. However, if the first insulating layer and the second semiconductor layer are sequentially stacked on the first semiconductor layer, It is not limited to the SOI substrate. Furthermore, although the first insulator layer and the second insulator layer are substantially parallel on the first semiconductor layer, they need only be approximately parallel on at least the cavity 18.

  Furthermore, in the first to third embodiments, the depth of the trench 48 (that is, the depth of the insulating film 20) is from the upper surface of the silicon layer 16 to the insulating layer 14, but for example, the insulating layer As long as it extends to the vicinity of 14, it may extend to the silicon substrate 12 through the insulator layer 14.

  In addition, dry etching is used as etching for removing the predetermined portion 46, but wet etching can also be used, but dry etching is used from the viewpoint of reducing damage to the infrared absorption film. It is preferable.

It is a top view of one embodiment of an infrared detection device concerning the present invention. It is sectional drawing along the II-II line of FIG. (A) is a manufacturing-process figure which shows 1 process of one Embodiment of the manufacturing method of the infrared rays detector which concerns on this invention. (B) is a manufacturing process figure showing the next process of (a). It is a manufacturing process figure which shows the next process of FIG.3 (b). It is a top view of the SOI substrate in the state where the cavity part was formed in the manufacturing method of an infrared detecting device. It is sectional drawing along the VI-VI line of FIG.5 (b). It is a top view of the modification of the infrared rays detection apparatus shown in FIG. It is sectional drawing along the VIII-VIII line of FIG. It is a top view of other embodiments of an infrared detection device concerning the present invention. FIG. 10 is a cross-sectional view of the infrared detection device shown in FIG. 9 along the line XX. It is a top view of the infrared rays detection apparatus which has FET. It is sectional drawing along the XII-XII line | wire of FIG. It is a manufacturing-process figure which shows other embodiment of the manufacturing method of the infrared rays detection apparatus which concerns on this invention. It is sectional drawing of the infrared rays detection apparatus manufactured with the manufacturing method shown in FIG. It is sectional drawing of the deformation | transformation form of the infrared rays detection apparatus shown in FIG.

Explanation of symbols

  10, 54, 58, 62, 76, 80 ... infrared detecting device, 12 ... silicon substrate (first semiconductor layer), 14 ... insulator layer (first insulator layer), 16 ... silicon layer (second layer) Semiconductor layer), 18 ... cavity, 20 ... insulating film, 22 ... insulator layer (second insulator layer), 24 ... infrared detector, 44 ... SOI substrate (laminated body), 46 ... predetermined portion, 48 ... trench, 74 ... insulator layer (second insulator layer).

Claims (10)

A method of manufacturing an infrared detection device having an infrared detection unit,
A stack including a first semiconductor layer, a first insulator layer stacked on the first semiconductor layer, and a second semiconductor layer stacked on the first insulator layer is prepared. Process,
Forming a trench on an outer periphery of the predetermined portion corresponding to a side surface of the trench after forming a trench at a boundary of the predetermined portion to be a cavity by etching in the second semiconductor layer;
Laminating a second insulator layer on the surface of the second semiconductor layer including the predetermined portion;
Forming the infrared detector on the second insulator layer so as to face the predetermined portion in the stacking direction;
After forming the infrared detecting portion, the predetermined portion is removed from the second semiconductor layer by etching, and is partitioned by the first insulator layer, the second insulator layer, and the insulating film. Forming the cavity;
With
The first insulator layer, the second insulator layer, and the insulating film are made of the same material;
Thermal conductivity of the first insulator layer, the second insulator layer, and the insulating film is smaller than the thermal conductivity of the first semiconductor layer and the second semiconductor layer,
A method of manufacturing an infrared detecting device.   2. The method of manufacturing an infrared detection device according to claim 1, wherein, in the step of forming the insulating film, the insulating film is formed by filling the trench with an insulating material after forming the trench.   2. The method of manufacturing an infrared detecting device according to claim 1, wherein, in the step of forming the insulating film, the insulating film is formed by oxidizing the second semiconductor layer after forming the trench.   2. The step of forming the hollow portion includes etching the predetermined portion using a hole as an etching hole extending from the predetermined portion to the surface on the second insulator layer side. The manufacturing method of the infrared rays detection apparatus as described in any one of -3. The step of forming the infrared detection unit includes:
Forming a plurality of etching holes for etching the predetermined portion, extending from the predetermined portion to the surface on the second insulator layer side; and
Forming an infrared absorption film that absorbs infrared rays after forming the plurality of etching holes;
Have
In the step of forming the plurality of etching holes, the plurality of etching holes are formed such that a part of the plurality of etching holes is located below the infrared absorption film, and the plurality of etching holes is formed. The other part of is formed so as to be located outside the infrared absorption film ,
In the step of forming the infrared detection part, after forming the infrared absorption film, a through hole connected to the etching hole located on the lower side of the infrared absorption film is formed,
In the step of forming the hollow portion, the predetermined portion is etched using the etching hole connected to the through hole and the through hole together with the etching hole located outside the infrared absorption film. The manufacturing method of the infrared rays detection apparatus as described in any one of Claims 1-3.   In the step of forming the infrared detector, the infrared detector is formed by forming an infrared absorbing film whose temperature is detected by the temperature detector after the temperature detector is formed on the second insulator layer. The manufacturing method of the infrared detection apparatus as described in any one of Claims 1-5 characterized by the above-mentioned. An infrared detector having an infrared detector,
A first semiconductor layer;
A first insulator layer stacked on the first semiconductor layer;
A second semiconductor layer formed on the first insulator layer and having a cavity formed therethrough along the stacking direction;
An insulating film formed on the inner wall surface of the cavity,
A second insulator layer that is stacked on the second semiconductor layer and supports the infrared detection unit so as to face the cavity in the stacking direction;
The infrared detection unit has an infrared absorption film that absorbs infrared rays,
In the infrared detection part and the second insulator layer, a plurality of holes as etching holes extending from the cavity part to the surface side of the infrared detection part are formed,
A part of the plurality of holes penetrates the infrared absorption film, and the other part of the plurality of holes is located outside the infrared absorption film,
The first insulator layer, the second insulator layer, and the insulating film are made of the same material;
Thermal conductivity of the first insulator layer, the second insulator layer, and the insulating film is smaller than the thermal conductivity of the first semiconductor layer and the second semiconductor layer,
An infrared detector characterized by that.   The infrared detection device according to claim 7, wherein the first insulator layer and the second insulator layer are substantially parallel at least in the cavity. The infrared detection unit further includes a temperature detection unit that is provided between the infrared absorption film and the second insulator layer and detects a temperature change of the infrared absorption film. The infrared detection apparatus according to any one of 8 . Having a plurality of the infrared detectors;
A distance between the first insulator layer and the second insulator layer is substantially equal between the cavities facing each of the infrared detectors in the stacking direction. The infrared detection device according to any one of claims 7 to 9 .

Images