Mechanical support structure, pyroelectric detector and method of forming the same

Abstract

Various embodiments may relate to a mechanical support structure for a pyroelectric detector. The mechanical support structure may include a base layer. The mechanical support structure may include a plurality of support blocks extending from the base layer, the plurality of support blocks being arranged to extend in a direction away from the base layer, and spaced apart from one another so that adjacent support blocks of the plurality of support blocks are disjointed from one another. In various embodiments, a peripheral portion of the plurality of support blocks extending from a peripheral portion of the base layer may be configured to be supported by a substrate and a central portion of the plurality of support blocks extending from a central portion of the base layer may be configured to be suspended over an opening of the substrate.

Description

MECHANICAL SUPPORT STRUCTURE, PYROELECTRIC DETECTOR AND METHOD OF FORMING THE SAME CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority of Singapore application No.10202500774S filed March 25, 2025, the contents of it being hereby incorporated by reference in its entirety for all purposes.TECHNICAL FIELD

[0002] Various embodiments of this disclosure may relate to a mechanical support structure. Various embodiments of this disclosure may relate to a pyroelectric detector. Various embodiments of this disclosure may relate to a method of forming a pyroelectric detector.BACKGROUND

[0003] Micro-electromechanical system (MEMS) based pyroelectric detectors typically include a thermal isolation layer, a bottom electrode, a pyroelectric sensing layer, a top electrode and an absorber. This stack of film layers is of micrometer thicknesses and are usually in membrane form, suspended in air to confine and retain the heat in the pyroelectric sensing layer for maximum current output. Device failure due to fracture or breakage of membranes are not uncommon and would affect device yield on a wafer. This issue is amplified as the membrane size increases and stack thickness reduces. A previously reported strategy mitigates membrane breakage by building a waffle-like silicon oxide (SiCh) mechanical structure at the bottom of the membrane, beneath the thermal isolation layer.SUMMARY

[0004] Various embodiments may relate to a mechanical support structure for a pyroelectric detector. The mechanical support structure may include a base layer. The mechanical support structure may include a plurality of support blocks extending from the base layer, the plurality of support blocks being arranged to extend in a direction away from the base layer , and spaced apart from one another so that adjacent support blocks of the plurality of support blocks are disjointed from one another. In various embodiments, a peripheral portion of the plurality of support blocks extending from a peripheral portion of the base layer may be configured to be supported by a substrate and a central portion of the plurality of support blocks extending from a central portion of the base layer may be configured to be suspended over an opening of the substrate.

[0005] Various embodiments may relate to a pyroelectric detector. The pyroelectric detector may include a substrate including an opening. The mechanical support structure may include a base layer. The mechanical support structure may include a plurality of support blocks extending from the base layer, the plurality of support blocks being arranged to extend in a direction away from the base layer, and spaced apart from one another so that adjacent support blocks of the plurality of support blocks are disjointed from one another. A peripheral portion of the plurality of support blocks extending from a peripheral portion of the base layer may be configured to be supported by the substrate and a central portion of the plurality of support blocks extending from a central portion of the base layer may be configured to be suspended over the opening of the substrate. The pyroelectric detector may further include a stacked arrangement on or over the mechanical support structure. The stacked arrangement may include a first electrode, a pyroelectric sensing layer on or over the first electrode, a second electrode on or over the pyroelectric sensing layer, and an absorber layer on or over the second electrode.

[0006] Various embodiments may relate to a method of forming a pyroelectric detector. The method may include forming a mechanical support structure on or over a substrate including an opening. The mechanical support structure may include a base layer. The mechanical support structure may also include a plurality of support blocks extending from the base layer, the plurality of support blocks being arranged to extend in a direction away from the base layer, and spaced apart from one another so that adjacent support blocks of the plurality of support blocks are disjointed from one another. A peripheral portion of the plurality of support blocks extending from a peripheral portion of the base layer may be configured to be supported by the substrate and a central portion of the plurality of support blocks extending from a central portion of the base layer may be configured to be suspended over the opening of the substrate. The method may also include forming a stacked arrangement on or over the mechanical support structure. The stacked arrangement may include a first electrode. The stacked arrangement may also include a pyroelectric sensing layer on or over the first electrode. The stacked arrangement may further include a second electrode over the pyroelectric sensing layer. The stacked arrangement may additionally include an absorber layer over the second electrode.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] In the drawings, like reference characters generally refer to the same parts throughout the different views. The drawings are not necessarily drawn to scale, emphasis instead generally being placed upon illustrating the principles of various embodiments. In the following description, various embodiments of the invention are described with reference to the following drawings.FIG. 1A shows a general illustration of a mechanical support structure for a pyroelectric detector according to various embodiments.FIG. IB shows a general illustration of a pyroelectric detector according to various embodiments.FIG. 2 shows a general illustration of a method of forming a pyroelectric detector according to various embodiments.FIG. 3 shows (a) a schematic illustrating a top planar view of the mechanical support structure with rounded corners and closer pitches nearing the periphery of the mechanical support structure according to various embodiments, and (b) a schematic illustrating the membrane area is required to be smaller than an area of the mechanical support structure according to various embodiments, but equal or larger than the device sensing area.FIG. 4A shows a three-dimensional (3D) perspective views of central portions of two different mechanical support structures according to various embodiments.FIG. 4B shows top planar views of the central portions of two different mechanical support structures according to various embodiments shown in FIG. 4A.FIG. 5 is a schematic showing a cross-sectional view of a pyroelectric detector according to various embodiments.FIG. 6 shows (A) a plot of y (in micrometers or pm) as a function of x (in millimeters) illustrating membrane curvature of a pyroelectric detector with a conventional mechanical support structure; (B) a plot of y (in micrometers or pm) as a function of x (in millimeters) illustrating membrane curvature of a pyroelectric detector with a mechanical support structure as illustrated by Embodiment 1 in FIGS. 4A - B according to various embodiments; and (C) a plot of y (in micrometers or pm) as a function of x (in millimeters) illustrating membrane curvature of a pyroelectric detector with a mechanical support structure as illustrated by Embodiment 2 in FIGS. 4A - B according to various embodiments.FIG. 7 shows a plot of voltage (in milli-Volts or mV) as a function of time (in seconds or s) illustrating variation of different pyroelectric detectors (with a conventional mechanical supportstructure, a mechanical support structure as illustrated by Embodiment 1 in FIGS. 4A - B according to various embodiments, and a mechanical support structure as illustrated by Embodiment 2 in FIGS. 4A - B according to various embodiments) over a period of 40 seconds.DESCRIPTION

[0008] The following detailed description refers to the accompanying drawings that show, by way of illustration, specific details and embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized and structural, logical, and electrical changes may be made without departing from the scope of the invention. The various embodiments are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments.

[0009] Features that are described in the context of an embodiment may correspondingly be applicable to the same or similar features in the other embodiments. Features that are described in the context of an embodiment may correspondingly be applicable to the other embodiments, even if not explicitly described in these other embodiments. Furthermore, additions and / or combinations and / or alternatives as described for a feature in the context of an embodiment may correspondingly be applicable to the same or similar feature in the other embodiments.

[0010] In the context of various embodiments, the articles “a”, “an” and “the” as used with regard to a feature or element include a reference to one or more of the features or elements.

[0011] In the context of various embodiments, the term “about” or “approximately” as applied to a numeric value encompasses the exact value and a reasonable variance, e.g. within 10% of the specified value.

[0012] As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. In other words, “A and / or B” may include or refer to A, B, or both A and B.

[0013] By “comprising” it is meant including, but not limited to, whatever follows the word “comprising”. Thus, use of the term “comprising” indicates that the listed elements are required or mandatory, but that other elements are optional and may or may not be present.

[0014] By “consisting of’ is meant including, and limited to, whatever follows the phrase “consisting of’. Thus, the phrase “consisting of’ indicates that the listed elements are required or mandatory, and that no other elements may be present.

[0015] Embodiments described in the context of one of the mechanical support structures / pyroelectric detectors are analogously valid for the mechanical support structures / pyroelectric detectors, embodiments described in the context of a method are analogously valid for a mechanical support structure / pyroelectric detector, and vice versa.

[0016] It may be desirable to provide a structure for providing mechanical support (i.e., a mechanical support structure) for inclusion in a pyroelectric detector, or a pyroelectric detector having such a structure which addresses the aforementioned problems and / or provides a useful alternative.

[0017] FIG. 1A shows a general illustration of a mechanical support structure for a pyroelectric detector according to various embodiments. The mechanical support structure may include a base layer 102. The mechanical support structure may include a plurality of support blocks 104 extending from the base layer 102, the plurality of support blocks 104 being arranged to extend in a direction away from the base layer 102, and spaced apart from one another so that adjacent support blocks of the plurality of support blocks 104 are disjointed from one another. In various embodiments, a peripheral portion of the plurality of support blocks 104 extending from a peripheral portion of the base layer 102 may be configured to besupported by a substrate and a central portion of the plurality of support blocks extending from a central portion of the base layer 102 may be configured to be suspended over an opening of the substrate.

[0018] In other words, various embodiments may relate to a support structure including a base layer 102 and a plurality of support blocks 104 extending from the base layer 102. The plurality of support blocks 104 may not be in direct contact with or directly joined to one another.

[0019] For avoidance of doubt, FIG. 1A is intended to provide a general illustration of features of a mechanical support structure according to various embodiments, and is not intended to limit, for instance, the number, dimensions, shapes, arrangement etc. of the various features. For instance, while FIG.1A shows six support blocks, various embodiments may include any suitable number of supporting blocks.

[0020] The base layer 102 may be or may be part of a thermal isolation layer, or may be in contact with a thermal isolation layer.

[0021] In various embodiments, the mechanical support structure may include or be formed by a thermally insulating material or materials. The base 102 and the plurality of support blocks 104 may include or be made of the thermally insulating material(s). The thermally insulating material(s) may be silicon dioxide (SiCh) or any other suitable thermally insulating material(s).

[0022] In various embodiments, the peripheral portion of the base layer 102 may surround or encircle the central portion of the base layer. Accordingly, the peripheral portion of the plurality of support blocks 104 may surround or encircle the central portion of the plurality of support blocks 104. Adjacent support blocks of the central portion of the plurality of support blocks 104 may be arranged to be spaced apart by a first gap and adjacent support blocks of the peripheral portion of the plurality of support blocks 104 may be arranged to be spaced apart by a second gap, such that a size of the first gap is larger than a size of the second gap. In otherwords, gaps between support blocks in the peripheral portion may be smaller than gaps between support blocks in the central portion. In various embodiments, the size of the first gap may be at least twice that of the size of the second gap.

[0023] In various embodiments, the plurality of support blocks may be arranged in columns and rows, the columns being substantially perpendicular to the rows. Support blocks forming the columns may be spaced apart and disjointed (i.e., spaced or separated) from support blocks forming the rows. In various other embodiments, the plurality of support blocks may be arranged in columns and rows that are at an angle (not necessarily at 90°) to each other. For example, the angle may of any value selected from a range from 15° to 90°, or from 30° to 90° or from 45° to 90°, or from 15° to 75°, or from 30° to 60°.

[0024] In various embodiments, each of the columns may be formed by a column set of support blocks (i.e., including multiple support blocks) and each of the rows may be formed by a row set of support blocks (i.e., including multiple support blocks). Support blocks of the column set of support blocks may be spaced apart and disjointed from one another, and support blocks of the row set of support blocks may be spaced apart and disjointed from one another.

[0025] In various other embodiments, each of the columns may be formed by a single support block and each of the rows are formed by a row set of support blocks. Support blocks of the row set of support blocks may be spaced apart and disjointed from one another.

[0026] In various embodiments, the plurality of support blocks may be arranged to be spaced apart from one another at a distance of between 500 nm to 10 pm.

[0027] In various embodiments, the base layer 102 may have a planar shape with rounded corners at the peripheral portion of the base layer 102.

[0028] In various embodiments, the plurality of support blocks 104 may be in the form of rectangular blocks.

[0029] FIG. IB shows a general illustration of a pyroelectric detector according to various embodiments. The pyroelectric detector may include a substrate 106 including an opening 106a. The pyroelectric detector may also include a mechanical support structure as shown in FIG. 1 A. The mechanical support structure may include a base layer 102. The mechanical support structure may include a plurality of support blocks 104 extending from the base layer 102, the plurality of support blocks 104 being arranged to extend in a direction away from the base layer 102, and spaced apart from one another so that adjacent support blocks of the plurality of support blocks 104 are disjointed from one another. A peripheral portion of the plurality of support blocks 104 extending from a peripheral portion of the base layer 102 may be configured to be supported by the substrate 106 and a central portion of the plurality of support blocks extending from a central portion of the base layer 102 may be configured to be suspended over the opening 106a of the substrate 106. The pyroelectric detector may further include a stacked arrangement on or over the mechanical support structure. The stacked arrangement may include a first electrode (alternatively referred to as bottom electrode) 108, a pyroelectric sensing layer 110 on or over the first electrode 108, a second electrode (alternatively referred to as top electrode) 112 on or over the pyroelectric sensing layer 110, and an absorber layer 114 on or over the second electrode 112.

[0030] In other words, various embodiments may include a pyroelectric detector including a substrate 106 and the mechanical support structure as shown in FIG. 1A on or over the substrate 106. A stacked arrangement including a first electrode 108, a second electrode 112, a pyroelectric sensing layer 110 sandwiched between the first electrode 108 and the second electrode 112, and an absorber layer 114 may be over the mechanical support structure.

[0031] For avoidance of doubt, FIG. IB is intended to provide a general illustration of features of a pyroelectric detector structure according to various embodiments, and is notintended to limit, for instance, the number, dimensions, shapes, arrangement etc. of the various features.

[0032] In various embodiments, the peripheral portion of the plurality of support blocks 104 may be embedded in the substrate 106. The peripheral portion of the plurality of support blocks 104 may be in direct contact with the substrate 106.

[0033] In various embodiments, an area of the base layer 102 may be equal to or larger than an area of the pyroelectric sensing layer 110.

[0034] The pyroelectric sensing layer 110 may include any suitable pyroelectric sensing material that generates a voltage when the temperature of the pyroelectric sensing material changes. Examples of suitable pyroelectric sensing materials may include aluminum nitride (AIN), scandium aluminum nitride (ScAlN), hafnium oxide (HfCh), lead zirconate titanate (PZT), lithium niobate (LiNbOs), or hafnium zirconium oxide (HZO).

[0035] In various embodiments, the absorber layer 114 may include any suitable material(s), e.g., dielectric material(s) such as silicon oxide (SiCh) or silicon nitride (SiN). In various embodiments, the absorber 114 may be a silicon oxide (SiCh) - silicon nitride (SiN) - silicon oxide (SiCh) stack.

[0036] In various embodiments, the first electrode 108 and / or the second electrode 112 may include any suitable electrically conductive material, e.g., aluminum (Al), molybdenum (Mo) or titanium nitride (TiN).

[0037] In various embodiments, the substrate 106 may include any suitable material, e.g., a semiconductor material such as silicon (Si), germanium (Ge), or silicon-germanium (SiGe).

[0038] In various embodiments, the opening 106a may extend through a thickness of the substrate 106, as shown in FIG. IB. In various other embodiments, the opening 106a may not extend through a thickness of the substrate 106. In other words, the detector may have the cavityenclosed by the mechanical support structure 102 and the substrate 106. The enclosed cavity may be formed using front-side cavity release.

[0039] In various embodiments, the pyroelectric detector may be a micro-electromechanical systems (MEMS) based pyroelectric infrared detector.

[0040] FIG. 2 shows a general illustration of a method of forming a pyroelectric detector according to various embodiments. The method may include, in 202, forming a mechanical support structure on or over a substrate including an opening. The mechanical support structure may include a base layer. The mechanical support structure may also include a plurality of support blocks extending from the base layer, the plurality of support blocks being arranged to extend in a direction away from the base layer, and spaced apart from one another so that adjacent support blocks of the plurality of support blocks are disjointed from one another. A peripheral portion of the plurality of support blocks extending from a peripheral portion of the base layer may be configured to be supported by the substrate and a central portion of the plurality of support blocks extending from a central portion of the base layer may be configured to be suspended over the opening of the substrate. The method may also include, in 204, forming a stacked arrangement on or over the mechanical support structure. The stacked arrangement may include a first electrode. The stacked arrangement may also include a pyroelectric sensing layer on or over the first electrode. The stacked arrangement may further include a second electrode over the pyroelectric sensing layer. The stacked arrangement may additionally include an absorber layer over the second electrode.

[0041] In other words, various embodiments may relate to forming a pyroelectric detector including forming a mechanical support structure as described herein on or over a substrate, and forming a stacked arrangement including a first electrode, a pyroelectric sensing layer, a second electrode, and an absorber layer on or over the mechanical support structure.

[0042] For avoidance of doubt, FIG. 2 is intended to illustrate steps of a method of forming a pyroelectric detector, and is not intended to limit the sequence of the steps. For instance, in various embodiments, the mechanical support layer may be formed on a substrate, followed by forming the stacked arrangement on the mechanical support layer, and thereafter forming the opening of the substrate (using backside etch), thereby also releasing part of the mechanical support structure exposed by the backside etch at the same time.

[0043] In one example, a substrate (e.g., silicon wafer) may be subjected to patterning and etching to form trenches. A suitable deposition method (e.g., Low-Pressure Chemical Vapor Deposition (LPCVD) tetraethyl orthosilicate (TEOS)) may be used to deposit a thermally insulating material, e.g., silicon oxide (SiCh), in the trenches and over the substrate, followed by chemical mechanical polishing (CMP) to form the mechanical support structure. Thereafter, a suitable electrically conductive material (e.g., molybdenum (Mo)) may be deposited, patterned and etched to form the first electrode (bottom electrode) on the mechanical support structure. A suitable pyroelectric sensing material (e.g., aluminum nitride (AIN)) may be deposited, patterned and etched to form a pyroelectric sensing layer on the first electrode. Another electrically conductive material (e.g., titanium nitride (TiN)) may be deposited, patterned and etched to form the second electrode (top electrode) on the pyroelectric sensing layer. The absorber layer (e.g., SiCh - SiN - SiCh stack) may then be formed on or over the second electrode. The substrate may then be subjected to backside thinning and etching to form the opening and release the mechanical support structure.

[0044] In various embodiments, adjacent support blocks of the central portion of the plurality of support blocks may be arranged to be spaced apart by a first gap and adjacent support blocks of the peripheral portion of the plurality of support blocks may be arranged to be spaced apart by a second gap, and a size of the first gap is larger than a size of the second gap-

[0045] In various embodiments, the plurality of support blocks may be arranged in columns and rows, the columns being perpendicular to the rows. Support blocks forming the columns may be spaced apart and disjointed from support blocks forming the rows.

[0046] In various embodiments, each of the columns may be formed by a column set of support blocks and each of the rows may be formed by a row set of support blocks. Support blocks of the column set of support blocks may be spaced apart and disjointed from one another, and support blocks of the row set of support blocks may be spaced apart and disjointed from one another.

[0047] In various other embodiments, each of the columns may be formed by a single support block and each of the rows may be formed by a row set of support blocks. Support blocks of the row set of support blocks may be spaced apart and disjointed from one another.

[0048] Various embodiments may relate to a method of forming a mechanical support structure. The method may include forming a base layer, and a plurality of support blocks extending from the base layer, the plurality of support blocks being arranged to extend in a direction away from the base layer, and spaced apart from one another so that adjacent support blocks of the plurality of support blocks are disjointed from one another. A peripheral portion of the plurality of support blocks extending from a peripheral portion of the base layer may be configured to be supported by a substrate and a central portion of the plurality of support blocks extending from a central portion of the base layer may be configured to be suspended over an opening of the substrate.

[0049] Various embodiments may relate to structural designs underneath the silicon oxide (SiCh) thermal isolation layer that may help to increase mechanical stiffness of large membranes and also increase the effective sensing area of pyroelectric devices or detectors. Pyroelectric device signal output depends on the size of the sensing area as shown in Equation(1). Accordingly, a mechanical support structure that could help increase sensing area may further enhance device performance.<where i is the current output (output signal) from the pyroelectric device, p is the pyroelectric coefficient of the sensing layer which is inherent to the material, A is the sensing area of the dTpyroelectric device and — is the rate of change of temperature with time.

[0050] Various embodiments may include rectangular structure (support blocks) arranged to increase mechanical stiffness of a membrane. The support blocks may include a thermally insulating material such as SiCh. FIG. 3 shows (a) a schematic illustrating a top planar view of the mechanical support structure with rounded corners and closer pitches nearing the periphery of the mechanical support structure according to various embodiments, and (b) a schematic illustrating the membrane area is required to be smaller than an area of the mechanical support structure according to various embodiments, but equal or larger than the device sensing area. The membrane referred to in FIG. 3(b) may correspond to the portion of the thermal isolation layer (base layer) that is suspended over the opening of the substrate, while the device sensing area may correspond to the lateral area of pyroelectric sensing layer.

[0051] While FIG. 3(a) shows a square mechanical support structure with rounded comers, it should be appreciated that other suitable shapes may be possible. The mechanical support structure may include rectangular structures (support blocks) arranged equally spaced apart from one another, and extending from the center of the square area towards the periphery of the square area. At periphery regions of the square area, the rectangular structures (support blocks) may be arranged to be more closely spaced apart compared to other regions of the square mechanical support structure. FIG. 3(b) shows that the size of the membrane can be as small as the device sensing area, but may overlap into the peripheral portion of the mechanical support structure.

[0052] FIG. 4A shows a three-dimensional (3D) perspective views of central portions of two different mechanical support structures according to various embodiments. Both embodiments shown in FIG. 4A include rectangular support blocks of SiCh, with gaps in between support blocks. The gaps may allow the pyroelectric sensing layer (which is also piezoelectric) lying above it to stretch and become bigger, thereby increasing its sensing area compared to structures with no gaps. For detectors with mechanical support structures without gaps, the continuous mechanical support structure may not allow the stretching / expansion of the overlying pyroelectric sensing layer.

[0053] FIG. 4B shows top planar views of the central portions of two different mechanical support structures according to various embodiments shown in FIG. 4 A. As shown in FIGS. 4 A - B, for both embodiments, the plurality of support blocks are arranged in columns and rows, the columns being perpendicular to the rows. Support blocks forming the columns are spaced apart and disjointed from support blocks forming the rows. For Embodiment 1, each of the columns is formed by a column set of support blocks and each of the rows is formed by a row set of support blocks, with support blocks of the column set of support blocks being spaced apart and disjointed from one another, and support blocks of the row set of support blocks being spaced apart and disjointed from one another. The distance between neighboring support blocks of the column set of support blocks (SI) may or may not be equal to the distance between neighboring support blocks of the row set of support blocks (S2). SI (or S2) may have any suitable value, e.g., a value selected from a range from 500 nm to 10 pm. In various embodiments, a support block of the column set and a support block of the row set may have the same or equal dimensions (i.e., same length (L) and same width (W)). However, it may be envisioned that in various other embodiments, a support block of the column set and a support block of the row set may have different dimensions (i.e., different lengths (L) and / or different widths (W)). In various embodiments, the length (L) maybe of any suitable value, e.g., selectedfrom a range from 4 um to 6 um, e.g., 5 um. The width (W) may be of any suitable value, e.g., selected from a range from 0.5 um to 1.5 um, e.g., 1 um. For Embodiment 2, each of the columns is formed by a single support block and each of the rows are formed by a row set of support blocks, with support blocks of the row set of support blocks being spaced apart and disjointed from one another. The distance between the single support block of a column and a neighboring support block of a row set (S) may have any suitable value, e.g., a value selected from a range from 500 nm to 10 pm. In various embodiments, the length LI may be of any suitable value, e.g., selected from a range from 4 um to 6 um, e.g., 5 um. The width W1 may be of any suitable value, e.g., selected from a range from 0.5 um to 1.5 um, e.g., 1 um. The width W2 may be of any suitable value, e.g., selected from a range from 0.5 um to 1.5 um, e.g., 1 um. The single support block forming each column may extend or run continuously across an entire width of the mechanical support structure, and the length L2 may be of any suitable value e.g., selected from a range from 50 um to 2000 um, e.g., 500 um.

[0054] FIG. 5 is a schematic showing a cross-sectional view of a pyroelectric detector according to various embodiments. The pyroelectric detector may include a substrate 506 including an opening 506a. The mechanical support structure may include a base layer 502 (alternatively referred to as thermal isolation layer). The mechanical support structure may include a plurality of support blocks 504 extending from the base layer 502, the plurality of support blocks 504 being arranged to extend in a direction away from the base layer 502, and spaced apart from one another so that adjacent support blocks of the plurality of support blocks 504 are disjointed from one another. A peripheral portion of the plurality of support blocks 504 extending from a peripheral portion of the base layer 502 may be configured to be supported by the substrate 506 and a central portion of the plurality of support blocks 504 extending from a central portion of the base layer 502 may be configured to be suspended over the opening 506a of the substrate 506. The pyroelectric detector may further include a stacked arrangementon or over the mechanical support structure. The stacked arrangement may include a first electrode (alternatively referred to as bottom electrode) 508, a pyroelectric sensing layer 510 on or over the first electrode 508, a second electrode (alternatively referred to as top electrode) 512 on or over the pyroelectric sensing layer 510, and an absorber layer 514 on or over the second electrode 512. As shown in FIG. 5, the plurality of support blocks 504 may extend away from the stacked arrangement including the first electrode 508, the pyroelectric sensing layer 510, the second electrode 512 and the absorber layer 514. The plurality of support blocks 504 may be mechanical structures configured to increase membrane stiffness, and may reduce the risk of the membrane from breaking.

[0055] FIG. 6 shows (A) a plot of y (in micrometers or pm) as a function of x (in millimeters) illustrating membrane curvature of a pyroelectric detector with a conventional mechanical support structure; (B) a plot of y (in micrometers or pm) as a function of x (in millimeters) illustrating membrane curvature of a pyroelectric detector with a mechanical support structure as illustrated by Embodiment 1 in FIGS. 4A - B according to various embodiments; and (C) a plot of y (in micrometers or pm) as a function of x (in millimeters) illustrating membrane curvature of a pyroelectric detector with a mechanical support structure as illustrated by Embodiment 2 in FIGS. 4A - B according to various embodiments. The membrane curvatures may be characterized by an optical profiler. The maximum vertical curvature of the membrane with a conventional mechanical support structure is +5.5 pm, while the maximum vertical curvature of the membrane with a mechanical support structure as illustrated by Embodiment 1 in FIGS. 4 A - B is -6.8 pm, and the maximum vertical curvature of the membrane with a mechanical support structure as illustrated by Embodiment 2 in FIGS. 4A - B is -6.6 pm. The higher the vertical deflection, the more the membrane stretches and expands, thereby indicating a larger sensing area.

[0056] FIG. 7 shows a plot of voltage (in milli-Volts or mV) as a function of time (in seconds or s) illustrating variation of different pyroelectric detectors (with a conventional mechanical support structure, a mechanical support structure as illustrated by Embodiment 1 in FIGS. 4 A - B according to various embodiments, and a mechanical support structure as illustrated by Embodiment 2 in FIGS. 4 A - B according to various embodiments) over a period of 40 seconds. Under the same experimental conditions, the maximum output voltages measured are -0.77 mV for the detector with the conventional mechanical support structure, -1.19 mV for the detector with the mechanical support structure as illustrated by Embodiment 1 in FIGS. 4 A -B, and -1.14 mV for the detector with the mechanical support structure as illustrated by Embodiment 2 in FIGS. 4A - B. The higher output voltage signifies that detectors with mechanical support structures according to various embodiments may perform better compared to the detector with the conventional mechanical support structure. A further calculation shows up to 54% increase in output voltage for the detector with the mechanical support structure as illustrated by Embodiment 1 in FIGS. 4 A - B.

[0057] Various embodiments may relate to mechanical support structures of pyroelectric detectors which maintain membrane integrity, increase mechanical stiffness and / or device output signal. Various embodiments may allow the pyroelectric sensing layer to stretch to a wider area when released into membrane structures, hence resulting in increased output signals. Various embodiments may allow the pyroelectric devices to have increased performance up to 54%. Various embodiments may be used for different applications, such as thermal and gas sensing.

[0058] Various embodiments may relate to mechanical support structures designed as discontinuous or disjointed rectangular support blocks that allow the pyroelectric sensing layer to expand to a larger area. The arrangement of the plurality of these rectangular support blocks may cover an area larger than the area of the pyroelectric sensing layer. This area formed bythe arrangement of the plurality of the rectangular blocks may form a shape (e.g. square) with rounded corners. The rectangular support blocks at the periphery of the shape may be spaced closer to one another compared to the rectangular support blocks that are further away from the periphery. The plurality of the rectangular support blocks has one surface attached to a base layer (e.g., a blanket layer of SiCh or thermal insulating layer) which connects the plurality of the rectangular support blocks to form a shape. The remaining surfaces of the rectangular blocks may be suspended in air, as part of a membrane. The rectangular blocks that are nearer to the periphery of the shape (e.g. square) are however embedded in the substrate, which may include silicon or any substrate carrier material. SiCh or a good thermal insulating material may be used to make these mechanical support blocks to ensure good containment of thermal energy in the pyroelectric detectors.

[0059] Various embodiments may relate to a structure for providing mechanical support to a pyroelectric detector including an absorber layer formed at a top side of the pyroelectric detector. The structure may include a plurality of support blocks extending from a base layer at a bottom side of the pyroelectric detector, the bottom side being opposite to the top side, the plurality of support blocks being arranged to extend in a direction away from the top side of the pyroelectric detector, wherein the plurality of support blocks are arranged to be spaced apart from one another so that adjacent support blocks of the plurality of support blocks are disjointed from one another, and wherein a peripheral portion of the plurality of support blocks extending from a peripheral portion of the base layer are being supported by a substrate and a central portion of the plurality of support blocks extending from a central portion of the base layer are being suspended over an opening.

[0060] By having the plurality of support blocks being spaced apart from one another, the gaps between adjacent support blocks allow the pyroelectric detector (e.g. a sensing layer or a pyroelectric film of the pyroelectric detector) lying over the plurality of support blocks to stretchand become bigger, thereby increasing its sensing area as compared to a support structure without gaps.

[0061] The structure may include the base layer, the base layer having a planar shape with rounded comers at the peripheral portion of the base layer, and wherein an area of the base layer may be equal to or larger than a sensing area of the pyroelectric detector. The base layer may have a rectangular or a square planar shape with rounded corners.

[0062] The structure may be integrated with the pyroelectric detector and the base layer may form part of a thermal isolation layer of the pyroelectric detector.

[0063] Various embodiments may relate to a structure for providing mechanical support to a pyroelectric detector including an absorber layer formed at a top side of the pyroelectric detector. The structure may include a plurality of support blocks extending from a base layer at a bottom side of the pyroelectric detector, the bottom side being opposite to the top side, the plurality of support blocks being arranged to extend in a direction away from the top side of the pyroelectric detector, wherein a peripheral portion of the plurality of support blocks extending from a peripheral portion of the base layer are being supported by a substrate and a central portion of the plurality of support blocks extending from a central portion of the base layer are being suspended over an opening, and wherein adjacent support blocks of the central portion of the plurality of support blocks are arranged to be spaced apart by a first gap and adjacent support blocks of the peripheral portion of the plurality of support blocks are arranged to be spaced apart by a second gap, and a size of the first gap is larger than a size of the second gap.

[0064] By having adjacent support blocks of the central portion of the plurality of support blocks being arranged to be spaced apart by a first gap and adjacent support blocks of the peripheral portion of the plurality of support blocks being arranged to be spaced apart by a second gap, and where a size of the first gap is larger than a size of the second gap, this providesimprovement to a mechanical stiffness of the structure for providing mechanical support to the pyroelectric detector.

[0065] Various embodiments may relate to a pyroelectric detector including an absorber layer formed at a top side of the pyroelectric detector; a pyroelectric sensing layer being sandwiched between a top electrode layer and a bottom electrode layer; a thermal isolation layer formed at a bottom side of the pyroelectric detector, wherein the top electrode layer, the pyroelectric sensing layer and the bottom electrode layer are sandwiched between the absorber layer and the thermal isolation layer, and a structure for providing mechanical support to the pyroelectric detector, the structure being integrated with the pyroelectric detector and includes a plurality of support blocks extending from the thermal isolation layer at a bottom side of the pyroelectric detector, the bottom side being opposite to the top side, the plurality of support blocks being arranged to extend in a direction away from the top side of the pyroelectric detector, wherein the plurality of support blocks are arranged to be spaced apart from one another so that adjacent support blocks of the plurality of support blocks are disjointed from one another, and wherein a peripheral portion of the plurality of support blocks extending from a peripheral portion of the thermal isolation layer are being supported by a substrate and a central portion of the plurality of support blocks extending from a central portion of the thermal isolation layer are being suspended over an opening.

[0066] The structure may be formed by a thermally insulating material, e.g., silicon dioxide (SiO2).

[0067] Adjacent support blocks of the central portion of the plurality of support blocks may be arranged to be spaced apart by a first gap and adjacent support blocks of the peripheral portion of the plurality of support blocks are arranged to be spaced apart by a second gap, and a size of the first gap is larger than a size of the second gap.

[0068] The size of the first gap may be at least twice that of the size of the second gap.

[0069] The peripheral portion of the plurality of support blocks may be embedded in the substrate. In an embodiment, the peripheral portion of the plurality of support blocks may be support on or formed on the substrate.

[0070] The plurality of support blocks may be arranged in columns and rows, the columns being perpendicular to the rows, and wherein support blocks forming the columns may be spaced apart and disjointed from support blocks forming the rows. In some embodiments, the plurality of support blocks may be arranged in columns and rows that are at an angle (not necessarily at 90°) to each other. For example, the angle may be in the range of 15° to 90° or 30° to 90° or 45° to 90° or 15° to 75° or 30° to 60°.

[0071] Each of the columns may be formed by a column set of support blocks and each of the rows may be formed by a row set of support blocks, each support block of the column set of support blocks and each support block of the row set of support blocks may be spaced apart and disjointed from one another. Disjointed would be understood to mean that the support blocks concerned are not joined to one another, even though they are formed extended from the base layer or the thermal isolation layer.

[0072] The plurality of support blocks may be arranged to be spaced apart from one another at a distance of between 500 nm to 10 pm.

[0073] The thermal isolation layer may have a planar shape with rounded corners at the peripheral portion of the thermal isolation layer, and an area of the thermal isolation layer may be equal to or larger than an area of the pyroelectric sensing layer.

[0074] The plurality of support blocks may be in the form of rectangular blocks or rectangular prism blocks. It should also be appreciated that support blocks of other suitable shapes (e.g. other polygonal shapes such as cube etc.) may be used.

[0075] The pyroelectric detector may include a micro-electromechanical systems (MEMS) based pyroelectric infrared detector. Other forms of pyroelectric detector may be used.

[0076] Various embodiments may relate to a pyroelectric detector including an absorber layer formed at a top side of the pyroelectric detector; a pyroelectric sensing layer being sandwiched between a top electrode layer and a bottom electrode layer; a thermal isolation layer formed at a bottom side of the pyroelectric detector, wherein the top electrode layer, the pyroelectric sensing layer and the bottom electrode layer are sandwiched between the absorber layer and the thermal isolation layer, and a structure for providing mechanical support to the pyroelectric detector, the structure being integrated with the pyroelectric detector and includes a plurality of support blocks extending from the thermal isolation layer at a bottom side of the pyroelectric detector, the bottom side being opposite to the top side, the plurality of support blocks being arranged to extend in a direction away from the top side of the pyroelectric detector, wherein a peripheral portion of the plurality of support blocks extending from a peripheral portion of the thermal isolation layer are being supported by a substrate and a central portion of the plurality of support blocks extending from a central portion of the thermal isolation layer are being suspended over an opening, and wherein adjacent support blocks of the central portion of the plurality of support blocks are arranged to be spaced apart by a first gap and adjacent support blocks of the peripheral portion of the plurality of support blocks are arranged to be spaced apart by a second gap, and a size of the first gap is larger than a size of the second gap.

[0077] Although various embodiments may include support blocks formed directly on a thermal isolation layer of a pyroelectric device, it should be appreciated that in various other embodiments, a structure for providing mechanical support to a pyroelectric detector may include a separate base layer and that the support blocks are formed on this base layer. The base layer in this case may be integrated with the thermal isolation layer or may be integrated with the pyroelectric device subsequently. In some embodiments, the base layer may include a thermal insulating material. In an embodiment where the base layer is a separate base layer, itmay be made of a same material as the thermal isolation layer of the pyroelectric detector and may be integrated with the pyroelectric detector.

Claims

Claims1. A mechanical support structure for a pyroelectric detector, the mechanical support structure comprising:a base layer; anda plurality of support blocks extending from the base layer, the plurality of support blocks being arranged to extend in a direction away from the base layer, and spaced apart from one another so that adjacent support blocks of the plurality of support blocks are disjointed from one another;wherein a peripheral portion of the plurality of support blocks extending from a peripheral portion of the base layer are configured to be supported by a substrate and a central portion of the plurality of support blocks extending from a central portion of the base layer is configured to be suspended over an opening of the substrate.

2. The mechanical support structure according to claim 1, wherein the mechanical support structure comprises a thermally insulating material.

3. The mechanical support structure according to claim 2, wherein the thermally insulating material is silicon dioxide (SiCh).

4. The mechanical support structure according to claim 1, wherein adjacent support blocks of the central portion of the plurality of support blocks are arranged to bespaced apart by a first gap and adjacent support blocks of the peripheral portion of the plurality of support blocks are arranged to be spaced apart by a second gap, such that a size of the first gap is larger than a size of the second gap.

5. The mechanical support structure according to claim 4, wherein the size of the first gap is at least twice that of the size of the second gap.

6. The mechanical support structure according to claim 1, wherein the plurality of support blocks are arranged in columns and rows, the columns being perpendicular to the rows, and wherein support blocks forming the columns are spaced apart and disjointed from support blocks forming the rows.

7. The mechanical support structure according to claim 6, wherein each of the columns is formed by a column set of support blocks and each of the rows is formed by a row set of support blocks, support blocks of the column set of support blocks are being spaced apart and disjointed from one another, and support blocks of the row set of support blocks are being spaced apart and disjointed from one another.

8. The mechanical support structure according to claim 6, wherein each of the columns is formed by a single support block and each of the rows are formed by a row set of support blocks, support blocks of the row set of support blocks are being spaced apart and disjointed from one another.

9. The mechanical support structure according to claim 1, wherein the plurality of support blocks are arranged to be spaced apart from one another at a distance of between 500 nm to 10 pm.

10. The mechanical support structure according to claim 1, wherein the base layer has a planar shape with rounded comers at the peripheral portion of the base layer.

11. The mechanical support structure according to claim 1 , wherein the plurality of support blocks are in the form of rectangular blocks.

12. A pyroelectric detector comprising:a substrate comprising an opening;a mechanical support structure comprising:a base layer; anda plurality of support blocks extending from the base layer, the plurality of support blocks being arranged to extend in a direction away from the base layer, and spaced apart from one another so that adjacent support blocks of the plurality of support blocks are disjointed from one another; wherein a peripheral portion of the plurality of support blocks extending from a peripheral portion of the base layer are configured to be supported by the substrate and a central portion of the plurality of support blocks extending from a central portion of the base layer is configured to be suspended over the opening of the substrate; anda stacked arrangement over the mechanical support structure, the stacked arrangement comprising:a first electrode;a pyroelectric sensing layer over the first electrode;a second electrode over the pyroelectric sensing layer; andan absorber layer over the second electrode.

13. The pyroelectric detector according to claim 12, wherein the peripheral portion of the plurality of support blocks are embedded in the substrate.

14. The pyroelectric detector according to claim 12,wherein an area of the base layer is equal to or larger than an area of the pyroelectric sensing layer.

15. The pyroelectric detector according to claim 12, wherein the pyroelectric detector is a micro-electromechanical systems (MEMS) based pyroelectric infrared detector.

16. A method of forming a pyroelectric detector, the method comprising:forming a mechanical support structure over a substrate comprising an opening, the mechanical support structure comprising:a base layer; anda plurality of support blocks extending from the base layer, the plurality of support blocks being arranged to extend in a direction away from the base layer, and spaced apart from one another so that adjacent support blocks of the plurality of support blocks are disjointed from one another; wherein a peripheral portion of the plurality of support blocks extending from a peripheral portion of the base layer are configured to be supportedby the substrate and a central portion of the plurality of support blocks extending from a central portion of the base layer is configured to be suspended over the opening of the substrate; andforming a stacked arrangement over the mechanical support structure, the stacked arrangement comprising:a first electrode;a pyroelectric sensing layer over the first electrode;a second electrode over the pyroelectric sensing layer; andan absorber layer over the second electrode.

17. The method according to claim 16, wherein adjacent support blocks of the central portion of the plurality of support blocks are arranged to be spaced apart by a first gap and adjacent support blocks of the peripheral portion of the plurality of support blocks are arranged to be spaced apart by a second gap, and a size of the first gap is larger than a size of the second gap.

18. The method according to claim 16, wherein the plurality of support blocks are arranged in columns and rows, the columns being perpendicular to the rows; and wherein support blocks forming the columns are spaced apart and disjointed from support blocks forming the rows.

19. The method according to claim 18, wherein each of the columns is formed by a column set of support blocks and each of the rows is formed by a row set of support blocks, support blocks of the column set of support blocks are being spaced apart anddisjointed from one another, and support blocks of the row set of support blocks are being spaced apart and disjointed from one another.

20. The method according to claim 18, wherein each of the columns is formed by a single support block and each of the rows are formed by a row set of support blocks, support blocks of the row set of support blocks are being spaced apart and disjointed from one another.

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