JP2006300816A - Infrared detector, and infrared solid imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an infrared detector generating no inclination in a detection part or the like by an internal stress, and also to provide an infrared solid imaging device including the same. <P>SOLUTION: This substantially rectangular infrared detector for detecting a temperature change of the detection part by a detection film includes: a substrate; the detection part provided with the detection film; a support leg for supporting the detection part on the substrate; and a wiring layer provided in the support leg and connected to the detection film. The infrared detector has a structure to bring the support leg into a condition axisymmetric to a normal to a substrate surface, in an intersection of diagonal lines of the infrared detector. The infrared solid imaging device includes the infrared detectors arranged matrixlikely. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an infrared detector and an infrared solid-state imaging device including the infrared detector, and more particularly to an infrared detector having a line-symmetric layout with respect to a center line and an infrared solid-state imaging device including the infrared detector.

A conventional infrared solid-state imaging device has a plurality of detectors for taking out infrared rays as electric signals. Each detector is provided on the detection unit having a detection film for detecting infrared rays, a support leg for holding the detection unit in a hollow state on the concave portion, and the detection unit for efficiently absorbing infrared rays. An umbrella structure part is included (for example, patent document 1).
US Patent 5,220,189

  However, in the conventional infrared solid-state imaging device, the layout of the detection unit and the support legs is asymmetrical with respect to the normal to the substrate surface (hereinafter referred to as “center line”) at the intersection of the diagonal lines of the detector. It was. For this reason, there has been a problem that the internal stress generated in the support legs, the detector, and the umbrella structure of the detector is asymmetric with respect to the center line of the detector, and the detector and the umbrella structure are inclined.

  In particular, in order to improve the infrared detection sensitivity and response speed of the detector, the tendency to occur when the detector is downsized becomes remarkable, the detector tilts and contacts the substrate, or the umbrella structure tilts and the support legs There is a problem in that the infrared detection sensitivity of the detector is reduced due to contact with.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an infrared solid-state imaging device in which an inclination of a detection unit or the like due to internal stress does not occur.

  The present invention is a substantially rectangular infrared detector for detecting a temperature change of the detection unit with a detection film, a substrate, a detection unit provided with the detection film, a support leg for supporting the detection unit on the substrate, A structure that is provided on the support leg and includes a wiring layer connected to the detection film, and in which the support leg is symmetrical with respect to the normal (center line) to the substrate surface at the intersection of the diagonal lines of the infrared detector It is an infrared detector characterized by having.

  The present invention is also an infrared solid-state imaging device, in which such infrared detectors are arranged in a matrix.

  As described above, according to the present invention, since the internal stress generated in the support leg or the like is symmetric with respect to the center line of the infrared detector, the inclination of the detection unit and the umbrella structure unit can be prevented, and the infrared detection unit It is possible to improve the manufacturing yield of the infrared solid-state imaging device.

Embodiment 1 FIG.
FIG. 1 is a perspective view of an infrared solid-state imaging device according to a first embodiment of the present invention, the whole being represented by 300. FIG. The infrared solid-state imaging device 300 according to the first embodiment includes a substrate 301. Provided on the substrate 301 are a detector array 502 in which a plurality of detectors 503 are arranged in a matrix, and a signal processing circuit 509 that processes electrical signals output from the detectors 503 and outputs them to the outside. Yes. The detector 503 and the signal processing circuit 509 are connected to the vertical signal line 302 and the horizontal signal line 303.
In the second to fourth embodiments described below, the external appearance of the infrared solid-state imaging device is substantially the same as that of the infrared solid-state imaging device 300 shown in FIG.

  FIG. 2 is an enlarged plan view of the detector 503 of the infrared solid-state imaging device 300 according to the first embodiment. 3 is a cross-sectional view of the infrared solid-state imaging device 300 of FIG. 2 when viewed in the II-II direction. For ease of explanation, the umbrella structure 507 and the protective film 307 are omitted in FIG.

  As shown in FIGS. 2 and 3, the detector represented as a whole by 503 includes a substrate 301 provided with a recess 506. Support legs 505 are provided on the substrate 301, and the detection legs 504 are held hollow on the recesses 506 by the support legs 505. A plate-shaped umbrella structure 507 is provided on the detection unit 504 in order to improve infrared detection efficiency.

  In the detection unit 504, the wiring layer 304 and the detection film 200 are installed. A wiring layer 304 is also provided on the support leg 505 to electrically connect the signal processing circuit 509 and the detection film 200. As the detection film 200, for example, any of a bolometer, a pyroelectric body, a thermocouple, and a PN junction diode is used. In the first embodiment, the detection film 200 is made of a PN junction diode. The wiring layer 304 is made of aluminum, for example.

Next, the principle by which the detector 503 detects infrared rays will be briefly described.
When infrared rays emitted from a subject to be imaged by the infrared solid-state imaging device 300 are incident on the detector 503 included in the detector array 502, the temperature of the detection unit 504 increases. At this time, the electrical characteristics of the detection film 200 change according to the temperature change. For each detector 504, the signal processing circuit 509 reads the change in electrical characteristics and outputs it to the outside. Thereby, a thermal image of the subject can be obtained.
Since the substrate 301 and the detection unit 504 are connected by the support leg 505, the temperature change of the detection unit 504 increases as the thermal conductance of the support leg 505 decreases, and the temperature sensitivity of the detector 503 increases.

Next, the internal stress of the support leg 505, the detector 504, and the umbrella structure 507 of the detector 503 will be considered.
As can be seen from FIG. 2, the detector 503 is held hollow above the recess 506 with the points B and the vicinity of the point B ′ of the support leg 505 as fulcrums. C is an intersection of diagonal lines of the substantially square detector 503.

  In the detector 503 according to the first embodiment, the support leg 505 has a so-called spiral shape, and the layout of the support leg 505, the detection unit 504, and the umbrella structure unit 507 has a center line passing through the point C (on the surface of the substrate 301). It is line symmetric with respect to a vertical line). For this reason, the internal stress generated in each part of the detector 503 is also symmetrical with respect to the center line CC, and the internal stress is balanced about the center line CC. As a result, the detection unit 504 held hollow on the recess 506 is maintained substantially parallel to the surface of the substrate 301 and does not tilt. Similarly, the umbrella structure part 507 formed on the detection part 504 is also arranged substantially parallel to the surface of the detection part 504 and is not inclined.

  As described above, in the detector 503 according to the first exemplary embodiment, the internal stress is axisymmetric with respect to the center line C-C. Therefore, the detection unit 504 is in contact with the substrate 301 or the umbrella structure unit 507 is supported. There is no contact with the leg 505. For this reason, failure of the infrared solid-state imaging device 300 due to contact can be prevented, and the manufacturing yield of the infrared solid-state imaging device 300 can be improved.

  In the detector 503 according to the first embodiment, the support legs 505 are line-symmetric with respect to the center line CC, but the wiring layer 501 included in the support legs 505 is line-symmetric. Don't be.

  Next, a manufacturing method of the infrared solid-state imaging device 300 according to the first embodiment will be described with reference to FIG. FIG. 4 is a cross-sectional view in the manufacturing process. In FIG. 4, the same reference numerals as those in FIG. 3 indicate the same or corresponding portions. This manufacturing process includes the following steps 1 to 7.

  Step 1: As shown in FIG. 4A, first, a substrate 301 is prepared. The substrate 301 is made of an SOI (Silicon On Insulator) substrate in which a silicon oxide film layer 401 and a silicon layer 402 are sequentially stacked on a silicon support substrate 400.

  Step 2: As shown in FIG. 4B, an isolation oxide film 305 is formed at a predetermined position by using a LOCOS (LOCal Oxidation of Silicon) isolation method or a trench isolation method.

  Step 3: As shown in FIG. 4C, a signal processing circuit 509 (not shown) is formed. Further, the detection film 200 is formed on the silicon support substrate 400 or the silicon layer 402 in the region where the detector array 502 is to be formed. Here, the detection film 200 is made of a PN junction diode.

  Step 4: As shown in FIG. 4D, an insulating film 306 made of silicon oxide is deposited on the entire surface.

  Step 5: As shown in FIG. 4E, a wiring layer 304 made of, for example, aluminum is formed on the insulating film 306, and a protective film 307 is further deposited on the wiring layer 304.

Step 6: As shown in FIG. 4F, an etching hole 508 is opened at a predetermined position of the insulating film 306 so as to be symmetric with respect to the above-described center line CC. Subsequently, a sacrificial layer 308 made of, for example, silicon is deposited.
Further, a plate-like umbrella structure portion 507 is formed on the sacrificial layer 308 so as to be symmetric with respect to the center line CC.

  Step 7: As shown in FIG. 4G, an etchant such as xenon fluoride is introduced from the etching hole 508 to remove the sacrificial layer 308, and the silicon support substrate 400 is selectively etched to form a recess. 506 is formed.

  Through the above steps, the infrared solid-state imaging device 300 including the detector 503 supported by the support legs 505 made of an insulating film and having the detector 504 and the umbrella structure 507 floating in the air is completed.

Embodiment 2. FIG.
FIG. 5 is a top view of a detector included in the infrared solid-state imaging device according to the second embodiment of the present invention, the whole being represented by 513, and FIG. It is sectional drawing at the time of seeing in a direction.
5 and 6, the same reference numerals as those in FIGS. 2 and 3 indicate the same or corresponding portions. For ease of explanation, the umbrella structure portion 507 and the protective film 307 are omitted in FIG.

  As can be seen from FIG. 5, the detector 513 according to the second embodiment has a layout in which the support legs 505 meander in a U-shape, that is, a so-called accordion shape. In such an accordion shape, the layout of the support leg 505, the detection unit 504, and the umbrella structure unit 507 is axisymmetric with respect to the center line passing through the point C. For this reason, as in the case of the first embodiment, the internal stress generated in each part of the detector 513 is also axisymmetric with respect to the center line CC, and as a result, is held hollow on the recess 506. The detection unit 504 is maintained substantially parallel to the surface of the substrate 301 and does not tilt. Similarly, since the structure of the umbrella structure portion 507 is also symmetrical with respect to the center line CC, the umbrella structure portion 507 is disposed substantially parallel to the surface of the detection unit 504 and does not tilt.

  As described above, also in the detector 513 according to the second embodiment, the internal stress is axisymmetric with respect to the center line CC, so that the detection unit 504 contacts the substrate 301 or the umbrella structure unit 507 There is no contact with the support leg 505. For this reason, failure of the infrared solid-state imaging device 300 due to contact can be prevented, and the manufacturing yield of the infrared solid-state imaging device 300 can be improved.

  In the detector 513 according to the second embodiment, the support leg 505 is line-symmetric with respect to the center line CC as in the detector 503 according to the first embodiment. The wiring layer 501 included in is not line symmetric.

  FIG. 7 is a cross-sectional view of the manufacturing process of the infrared solid-state imaging device 300 according to the second embodiment. In FIG. 7, the same reference numerals as those in FIG. 4 indicate the same or corresponding parts.

  In this manufacturing process, as in the first embodiment, after performing steps 1 to 4 (FIGS. 7A to 7D), steps 5 and 6 (FIGS. 7E and 7F) are performed. , Accordion-shaped support legs 505 (including the wiring layer 304) are formed.

  Further, in step 7 (FIG. 7G), a recess 506 is formed.

  Through the above steps, the infrared solid-state imaging device 300 on which the detector 513 supported by the accordion-shaped support leg 505 and the detector 504 and the umbrella structure 507 are floated is completed.

Embodiment 3 FIG.
FIG. 8 is a top view of a detector included in the infrared solid-state imaging device according to the third embodiment of the present invention, the whole of which is represented by 523.
In FIG. 8, the same reference numerals as those in FIG. 2 indicate the same or corresponding portions, and the umbrella structure portion 507 and the protective film 307 are omitted for easy explanation.

  In the detector 523 according to the third embodiment, the layout of the support leg 505, the detection unit 504, and the umbrella structure unit 507 is the same as that of the detector 503 according to the first embodiment with respect to the center line passing through the point C. Are line symmetric. Furthermore, the wiring layer 501 included in the support leg 505 is also arranged symmetrically with respect to the center line CC.

  As described above, also in the detector 523 according to the third embodiment, the internal stress is axisymmetric with respect to the center line CC, so that the detection unit 504 is in contact with the substrate 301 or the umbrella structure unit 507 is There is no contact with the support leg 505. For this reason, failure of the infrared solid-state imaging device 300 due to contact can be prevented, and the manufacturing yield of the infrared solid-state imaging device 300 can be improved.

  In particular, in the detector 523 according to the third embodiment, the wiring layer 501 included in the support leg 505 is also line symmetric with respect to the center line CC, and the inclination of the detection unit 504 and the like due to internal stress is prevented. it can.

  Note that the wiring layer 501 included in the support leg 505 is a wiring layer inside (on the detection unit 504 side) from the broken line shown in FIG. Since the wiring layer outside the broken line is connected to the vertical signal line 302 or the horizontal signal line 303, the wiring layer is generally not point-symmetrical.

  The manufacturing process of the infrared solid-state imaging device according to the third embodiment is substantially the same as the manufacturing process of the first embodiment shown in FIG.

Embodiment 4 FIG.
FIG. 9 is a top view of a detector included in the infrared solid-state imaging device according to the fourth embodiment of the present invention, the whole being represented by 533.
9, the same reference numerals as those in FIG. 2 indicate the same or corresponding parts, and the umbrella structure portion 507 and the protective film 307 are omitted for easy explanation.

  In the detector 533 according to the fourth embodiment, like the detector 513 according to the second embodiment, the support leg 505 has a so-called accordion shape, and the layout of the support leg 505, the detection unit 504, and the umbrella structure unit 507 is the same. The line is symmetrical with respect to the center line passing through the point C. In addition, the wiring layer 501 included in the support leg 505 is also arranged symmetrically with respect to the center line passing through the point C.

  In the detector 533 according to the fourth embodiment, since the internal stress is axisymmetric with respect to the center line passing through the point C, the detection unit 504 comes into contact with the substrate 301 or the umbrella structure unit 507 is attached to the support leg 505. There is no contact. For this reason, failure of the infrared solid-state imaging device 300 due to contact can be prevented, and the manufacturing yield of the infrared solid-state imaging device 300 can be improved.

  In particular, in the detector 533 according to the fourth embodiment, the wiring layer 501 included in the support leg 505 is also line-symmetric with respect to the center line, and the inclination of the detection unit 504 and the like due to internal stress can be prevented.

  Note that the wiring layer 501 included in the support leg 505 refers to a wiring layer included in the support leg 505 on the inner side (detection unit 504 side) than the broken line illustrated in FIG. 9. Note that the wiring layer outside the broken line is connected to the vertical signal line 302 or the horizontal signal line 303 and thus is not symmetric with respect to the center line.

  Further, the manufacturing process of the infrared solid-state imaging device according to the fourth embodiment is substantially the same as the manufacturing process of the second embodiment shown in FIG.

It is a perspective view of the infrared solid-state imaging device concerning Embodiment 1 of the present invention. It is a top view of the detector concerning Embodiment 1 of the present invention. It is sectional drawing of the detector concerning Embodiment 1 of this invention. It is sectional drawing of the manufacturing process of the detector concerning Embodiment 1 of this invention. It is a top view of the detector concerning Embodiment 2 of the present invention. It is sectional drawing of the detector concerning Embodiment 2 of this invention. It is sectional drawing of the manufacturing process of the detector concerning Embodiment 2 of this invention. It is a top view of the detector concerning Embodiment 3 of this invention. It is a top view of the detector concerning Embodiment 4 of this invention.

Explanation of symbols

200 sensing film, 300 infrared solid-state imaging device, 301 substrate, 302 vertical signal line, 303 horizontal signal line, 304 wiring layer, 305 isolation oxide film, 306 insulating film, 307 protective film, 308 sacrificial layer, 400 silicon support substrate, 401 Silicon oxide film layer, 402 Silicon layer, 501 Wiring layer included in support leg, 502 detector array, 503 detector, 504 detector, 505 support leg, 506 recess, 507 umbrella structure, 508 etching hole, 509 signal processing circuit.

Claims (5)

It is a substantially rectangular infrared detector that detects a temperature change of the detection unit with a detection film,
A substrate,
A detection unit provided with a detection film;
A support leg for supporting the detection unit on the substrate;
A wiring layer provided on the support leg and connected to the sensing film;
An infrared detector having a structure in which the support leg is line-symmetric with respect to a normal to the substrate surface at the intersection of diagonal lines of the infrared detector.   The infrared detector according to claim 1, wherein the wiring layer provided on the support leg has a structure that is line-symmetric with respect to the normal line. It is a substantially rectangular infrared detector that detects a temperature change of the detection unit with a detection film,
A substrate,
A detection unit provided with a detection film;
A support leg for supporting the detection unit on the substrate;
A wiring layer provided on the support leg and connected to the sensing film;
An infrared detector characterized by having a structure in which the detector is line-symmetric with respect to a normal to the substrate surface at the intersection of diagonal lines of the infrared detector. It is a substantially rectangular infrared detector that detects a temperature change of the detection unit with a detection film,
A substrate,
A detection unit provided with a detection film;
A support leg for supporting the detection unit on the substrate;
A wiring layer provided on the support leg and connected to the detection film;
A plate-shaped umbrella structure supported on the detection unit,
An infrared detector having a structure in which the umbrella structure is line-symmetric with respect to a normal to the substrate surface at an intersection of diagonal lines of the infrared detector. An infrared solid-state imaging device, wherein the infrared detectors according to claim 1 are arranged in a matrix.

Images