Manufacturing process for detection circuits
The method addresses fabrication challenges of metasurfaces in infrared detectors by integrating them on detection circuits before assembly, achieving high-yield and cost-effective production through precise alignment and compatible manufacturing processes.
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Applications
- Current Assignee / Owner
- THALES SA
- Filing Date
- 2024-12-23
- Publication Date
- 2026-06-26
AI Technical Summary
The fabrication of metasurfaces in infrared detectors faces challenges such as high aspect ratio microstructures requiring precise electron beam lithography, alignment difficulties, and incompatibilities with readout circuits, leading to costly and inefficient production.
A method for collectively integrating metasurfaces on the rear faces of detection circuits before assembly with readout circuits, using temporary bonding and alignment holes, enabling precise alignment and compatible with standard manufacturing processes.
Facilitates high-yield, cost-effective production of infrared detectors with metasurfaces by ensuring precise alignment and handling, overcoming technological barriers and reducing production costs.
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Abstract
Description
Title of the invention: Method for manufacturing detection circuits FIELD OF INVENTION
[0001] The present invention relates to infrared (IR) detectors based on III-V semiconductor materials. More particularly, the invention deals with a method for the collective fabrication of detection circuits integrating microstructures, as well as the fabrication of optical detectors with such detection circuits. STATE OF THE ART
[0002] The architecture of a generic IR detector is based on an assembly of a detection circuit comprising an array of elementary pixels, which transforms an incident photon flux into photogenerated carriers, and a readout circuit (commonly called ROIC for "Read Out Integrated Circuit") to process the electrical signal from the pixels. This assembly is called a hybridization, and the resulting circuit is called a hybrid circuit, which is an optical detector.
[0003] A detection circuit consists of a pixel matrix, in which each pixel corresponds to an IR photodetector, enabling the conversion of IR radiation into an electrical signal. The spectral ranges addressed by the detection circuits are the near-infrared (NIR), mid-infrared (MWIR), and far-infrared (LWIR). The pixels of the detection circuit typically comprise a stack of different layers, including an active layer to transform the detected photons into charge carriers and contact layers to transfer the electrical signal from the pixel to the readout circuit.
[0004] It is known in the prior art to fabricate, on the so-called rear face of the detection circuit, that is, on the face of the substrate opposite the pixels and which receives the incident optical wave, microstructures forming a metasurface that act on the incident optical wave before it arrives at the pixel. A set of microstructures is associated with a pixel, this set having, for example, the function of deflecting, focusing, or polarizing the radiation incident on the pixel.
[0005] A metallens performs a lens function and comprises all the microstructures associated with each pixel. This metallens increases the collection efficiency for each pixel by focusing the radiation through the substrate.
[0006] Microstructures can be of different types, implementing different physical phenomena.
[0007] As a first example, we can cite microstructures creating an effective index enabling the realization of optical functions, for example microlenses such as described in the publication by Zhang et al., "Solid-Immersion Metalens for Infrared Focal Plane Arrays" (arXiv / physics). In this case, the microstructures have a sub-wavelength dimension, that is, a dimension smaller than the so-called operating wavelength corresponding to that detected by the active layer of the pixel. For a sensitivity within a given spectral range, the microstructures have a dimension smaller than the lower bound of the spectral band.
[0008] According to a second example, we can also cite resonator-type microstructures (nano-antennas) forming a Huygens metasurface, as described in documents EP3662511 and US11171168 for focusing applications in an IR detector. In this case, the microstructures form resonators, with a size on the order of the wavelength, typically plasmonic antennas, which re-emit (radiate), from an incident wave, light having a resonance wavelength, by modifying the phase of the incident wave.
[0009] The microstructures can be made directly in the substrate of the detection circuit, or in an additional layer (dielectric, metallic) deposited on the substrate.
[0010] The design parameters of the metasurface depend on the desired function, the type of microstructure and the targeted spectral detection band.
[0011] However, the fabrication of this type of structure presents numerous challenges. A primary difficulty arises from the fabrication of the metasurfaces themselves. For example, some of these microstructures exhibit a high aspect ratio, such as those composed of IILV semiconductor pillars etched to a depth of a few microns. Their fabrication requires a specific process using an electron beam lithography step and dry etching, which must be perfectly controlled to guarantee the desired effect on the incident signal. Constraints on maintaining the dimensions of the microstructures are important to ensure their optical properties.
[0012] A second difficulty concerns the alignment of these microstructure assemblies with their respective pixels. A strategy for aligning the patterns on the back side of the different detection circuits present on the substrate must be implemented to guarantee an alignment that is less than one micron.
[0013] A third difficulty arises in the manufacturing sequence. In a standard manufacturing process for detection circuits, the metasurface would be fabricated after hybridization on the readout circuit. However, this method would encounter potential technological incompatibilities (thermal budget, handling, risk of circuit damage by electrostatic discharge, etc.).
[0014] Another difficulty arises from the collective fabrication of the metasurfaces. It is impossible and inconceivable to fabricate these metasurfaces once the detection circuit has been transferred to the reading circuit. Indeed, the manipulation of the hybridized components is difficult, and the integration of these objects into electron beam lithography and dry etching processes is incompatible, at the risk of damaging the component.
[0015] Even if this were possible, the realization of the metasurfaces on each hybridized component would be very long and costly to implement, and ultimately incompatible with high industrial yield production.
[0016] One object of the present invention is to overcome the aforementioned drawbacks by providing a method for manufacturing detection circuits that collectively integrate metasurfaces on their rear faces, prior to assembly with their readout circuit. Furthermore, the method for manufacturing the detection circuits according to the invention can be incorporated into a manufacturing process for a complete hybrid component. DESCRIPTION OF THE INVENTION
[0017] The present invention relates to a method for manufacturing a plurality of optical detection circuits, said optical detection circuits being intended to be assembled with reading circuits to form optical detectors, and being configured to detect an incident optical wave comprising a wavelength referred to as the operating wavelength, the method comprising the steps of:
[0018] To have an initial substrate common to said plurality of circuits, made of III-V semiconductor material, having a front face on which is arranged a plurality of sets of pixels and a rear face, a pixel being configured to convert a detected optical wave into an electrical signal,
[0019] B to make alignment holes on said front face having a so-called reference depth of between 5 and 50 pm,
[0020] C transfers a first intermediate substrate onto the said front face of the initial substrate by gluing,
[0021] Thinning the rear face of the initial substrate until reaching the bottom of said alignment holes, said initial substrate then having a thickness equal to said reference depth and being called the thinned substrate,
[0022] To collectively realize, for the plurality of sets of pixels, a structuring of the back face so as to realize a plurality of associated metasurfaces, a metasurface comprising microstructures having a dimension less than or equal to said operating wavelength (X0), a set of microstructures being associated with a pixel, arranged with respect to said pixel in a predetermined manner and configured to modify the optical wave incident on said associated pixel,
[0023] F transfers a second intermediate substrate onto the structured rear face by bonding,
[0024] G remove the first intermediate substrate,
[0025] each set of pixels of the plurality of sets of pixels, arranged on a fraction of the thinned substrate and having a back face on which an associated metasurface is made, forming an optical detection circuit.
[0026] According to one embodiment, the C and F bonding steps are carried out with a photosensitive polymer.
[0027] According to one embodiment, the bonding of the first intermediate substrate in step C is carried out with a first polymer sensitive in a first spectral band, and the bonding of the second intermediate substrate in step F is carried out with a second polymer sensitive in a second spectral band different from the first spectral band.
[0028] According to one embodiment, step G of removing the first intermediate substrate is carried out by peeling with a first laser beam having a first wavelength included in the first spectral band and not included in the second spectral band, the first intermediate substrate being transparent to said first wavelength
[0029] According to one embodiment, the first and / or second intermediate substrate are made of glass or silicon.
[0030] According to another aspect, the invention relates to a first variant of a method for making an optical detector comprising the steps of:
[0031] H1 to have a plurality of optical detection circuits arranged on the second intermediate substrate as obtained at the end of step G of the process according to one aspect of the invention,
[0032] It separates said optical detection circuits bonded to said second intermediate substrate from each other,
[0033] J1 for an optical detection circuit, treat a surface of the pixels of said optical detection circuit in preparation for an assembly,
[0034] Kl assemble by hybridization said optical detection circuit bonded to said second intermediate substrate with a reading circuit,
[0035] L1 remove the second intermediate substrate, an optical detection circuit assembled with a readout circuit forming an optical detector.
[0036] According to another aspect, the invention relates to a second variant of a method for making an optical detector comprising the steps of:
[0037] H2 has a plurality of optical detection circuits arranged on the second intermediate substrate as obtained at the end of step G of the process according to one aspect of the invention,
[0038] 12 collectively process a surface of pixels from the plurality of detection circuits optics, in preparation for assembly,
[0039] J2 assemble by hybridization said plurality of optical circuits with a plurality of associated reading circuits implemented on a common substrate,
[0040] K2 remove the second intermediate substrate,
[0041] L2 separate from each other the said optical detection circuits assembled with the said associated reading circuits, an optical detection circuit assembled with a reading circuit forming an optical detector.
[0042] According to one embodiment of an optical detector, the bonding of the second intermediate substrate was implemented with a second polymer sensitive in a second spectral band, and the L1 or K2 step of removal of the second intermediate substrate is carried out by peeling with a second laser beam having a second wavelength included in the second spectral band and not included in the first spectral band, the second intermediate substrate being transparent to said second wavelength.
[0043] According to one embodiment, in step F the second polymer was positioned in areas located outside the metasurfaces, and the second laser beam operating the take-off in step L1 or in step K2 is oriented so as to illuminate said areas.
[0044] The following description presents several embodiments of the device of the invention: these examples are not limiting to the scope of the invention. These embodiments present both the essential features of the invention and additional features related to the embodiments considered.
[0045] The invention will be better understood and other features, objectives and advantages thereof will become apparent from the following detailed description and with reference to the accompanying drawings given by way of non-limiting examples and in which:
[0046] Fig. 1 illustrates the different stages of the manufacturing process of a plurality of circuits according to the invention.
[0047] Figure 2 illustrates the technological steps A to D according to the invention.
[0048] Figure 3 illustrates the initial substrate after step B according to the invention.
[0049] Figure 4 illustrates the technological steps E to G according to the invention.
[0050] Figure 5 illustrates the diagram of the different stages H1 to L1 of a first variant of a method for implementing a detection circuit according to the invention.
[0051] Figure 6 schematically illustrates the technological steps H1 to LL
[0052] Figure 7 illustrates the diagram of the different stages H2 to L2 of a second variant of the method for making a detection circuit according to the invention.
[0053] Figure 8 schematically illustrates the technological steps H2 to L2. DETAILED DESCRIPTION OF THE INVENTION
[0054] The invention relates to a method 100 for manufacturing a plurality of optical detection circuits CD. The method is collective, meaning that the CD circuits of the plurality are manufactured simultaneously. The optical detection circuits CD are intended to be assembled with readout circuits CL to form optical detectors DO (also called hybrid CH circuits). The detection circuits CD are configured to detect an incident optical wave OIB comprising a wavelength X0, referred to as the operating wavelength. An optical detection circuit is configured to detect the operating wavelength, that is, to transform the optical wave at X0 or in a spectral band around X0 into an electrical signal.
[0055] The different steps A to G of the process 100 according to the invention are listed [Fig.1] and the technological steps are illustrated [Fig.2] (steps A to D) and [Fig.4] (steps E to G).
[0056] A first step A consists of having a common substrate SUB, called the initial substrate, made of III-V semiconductor material Mat, illustrated in [Fig. 3]. The substrate SUB has a front face called FAV on which a plurality of pixel sets Ens Pix are arranged. A pixel is configured to convert the detected incident optical wave into an electrical signal. Typically, the pixels of a set Ens are arranged in a matrix. The substrate SUB also includes a back face FAR.
[0057] In a step B, alignment holes HO are made on the face, also illustrated [Fig.3]. The holes have a so-called reference depth d between 5 and 50 pm, and a preferably square shape, with a width between 5 and 50 pm.
[0058] According to one embodiment, the holes are arranged around the periphery of the pixel sets. This makes it possible to multiply the number of alignment elements through which the final alignment will be achieved, without hindering the manufacturing process.
[0059] Fig. 3 illustrates an example of an initial SUB substrate with four matrix Ens sets of pixels, one matrix set being intended to form a CD detection circuit, with the HO holes at the periphery of the Ens sets.
[0060] Preferably, the holes are made by dry etching. The advantage of dry etching is that it preserves anisotropy in the dimensions. Thus, deep patterns can be created without spreading horizontally.
[0061] As explained later, the holes will allow the final thickness of the CD detection circuit to be defined after thinning (see step D). The holes will also serve as alignment marks for the future lithography of the metasurfaces (see step E). Indeed, it is essential to perfectly align the metasurfaces etched on the back side with the Pix pixels arranged on the front side.
[0062] In step C, a first intermediate substrate SH1 is (temporarily) attached to the front face of the SUB substrate by bonding with a first adhesive, referenced GL1. The intermediate substrate SH1 mechanically stabilizes the complete vertical structure during the thinning of the rear face of the III-V substrate (see step D). Its presence allows for handling without risk of breakage of the III-V SUB substrate. Excessive mechanical deformation of the III-V SUB substrate after thinning is avoided, as this could compromise its flatness and, consequently, the quality of the lithography of the metasurfaces (Step E).
[0063] In a step D, the rear face FAR of the substrate SUB is thinned until the bottom of the holes HO is reached. The substrate then has a thickness determined by the holes HO and equal to the reference depth d. Once thinned, the substrate, designated SUBa in [Fig.2] and 4, typically has a thickness d between 5 and 50 µm.
[0064] The thinning is for example of a mechano-chemical type.
[0065] In a step E, the rear face is collectively structured for the plurality of pixel sets Ens to create a plurality of associated metasurfaces MS. A metasurface MS comprises microstructures MST having a dimension less than or equal to the operating wavelength X0. Each pixel Pix is associated with a set of microstructures s, arranged relative to the pixel in a predetermined manner and configured to modify the optical wave incident on the pixel Pix. For example, a set of microstructures opposite the associated pixel is configured to create a microlens with a predetermined focal length, typically equal to the thickness d of the thinned substrate, so as to focus the light incident on the rear face FAR onto the detection pixels after passing through the thinned substrate SUBa.
[0066] The metasurface can be based on effective index microstructures or Huygens microstructures, as described above, or any other type of microstructure allowing modification of the path or polarization of the incident wave.
[0067] The fabrication of metasurfaces is typically carried out by lithography and dry etching. Dry etching is anisotropic compared to wet etching, which is isotropic. The dimensions of the microstructures are thus preserved during the transfer.
[0068] A perfect alignment of the metasurfaces with the corresponding pixels on the front face is obtained using the predefined holes before step C of bonding with the first host substrate SH1.
[0069] In a step F, a second intermediate substrate SH2 is transferred onto the structured rear face (metasurface side) by gluing, with a second glue referenced GL2.
[0070] According to one embodiment, the intermediate substrates SH1 and / or SH2 are made of glass or silicon.
[0071] In a step G, the first intermediate substrate SH1 is removed.
[0072] Each set of pixels Ens of the plurality of sets of pixels is arranged on a fraction of the thinned substrate and presents a back face on which an associated metasurface is made. The assembly comprising the matrix Ens of pixels Pix arranged on a fraction of the associated thinned substrate, the back face of which is structured with an associated metasurface, forms an optical detection circuit CD.
[0073] At the end of step G, we thus have a structure 30 comprising a plurality of optical detection circuits CD, the structured face of each of the substrates of the CD circuits being glued to the same substrate, the second intermediate substrate SH2.
[0074] In summary, the method 100 according to the invention is based on two steps of temporarily bonding the SUB substrate on which the detection circuits have been fabricated. First, the front face of the SUB III-V substrate, containing the pixels of several detection circuits, is temporarily bonded to a host substrate SH1. The exposed face of the SUB IILV substrate is then thinned to the desired thickness. The fabrication of the metasurfaces then becomes possible. In order to remove the first host substrate SH1, a new temporary support SH2 is placed on the metasurface side.
[0075] The final detectors are not yet individualized (the reading circuit is missing). This structure 30 can be transported from one production line to another, possibly located in a different place, or even in a different factory.
[0076] An advantage of the method 100 according to the invention is the collective fabrication of metasurfaces on the back side of the flat substrate of the detection circuits, before transfer to their readout circuit. This fabrication is achieved by ensuring the perfect positioning of the metasurface patterns through self-alignment, thus differentiating it from other lithography approaches that conventionally use alignment marks. All conventional microelectronic fabrication technologies can be used in terms of lithography or plasma dry etching. The IILV SUB material and its SH1 / SH2 host substrates are compatible with all standard equipment.
[0077] The process according to the invention also offers a handling advantage, since the SUB substrate is thinned to achieve the desired thickness on its back face. The temporary bonding also allows for safe handling of the III-V (SUB) wafer, ensuring a flat back face that facilitates the fabrication of the metasurfaces.
[0078] The process according to the invention overcomes the technological barrier which until now required that each metasurface be produced on the finalized and individualized optical detector, that is to say, already assembled to the reading circuit. This realization Individual production is indeed very difficult in terms of handling and is not compatible with existing equipment, which leads to a prohibitively high production yield.
[0079] The fabrication of the metasurfaces is integrated into the fabrication process of the detection circuits on a common substrate. The optical detection circuits are located on the common wafer SUB, which can receive the fabrication of the metasurfaces on its back side via a planar collective process.
[0080] In addition, the flatness of the SUB substrate and the alignment accuracy of the metasurfaces with the Pix pixels of the front face allow for a high manufacturing yield.
[0081] In addition, the process 100 allows simpler handling of the IILV SUB substrate on which the detection circuits and metasurfaces are made, particularly during the thinning step D.
[0082] Thus, process 100 is based on two key points:
[0083] - The temporary double bonding of the IILV SUB substrate, containing the circuits of detection, thus enabling the creation of metasurfaces, using glass or silicon host substrates.
[0084] - The perfect alignment of the metasurfaces with the pixels manufactured on the front face at using pre-drilled holes before gluing.
[0085] The finalization of the detectors can be carried out in two ways, depending on how they are combined with the readout circuit. Hybridization refers to the assembly of the optical and electronic parts of a detector without affecting its optical / electronic performance. The resulting detector is commonly called a hybrid circuit. Hybridization is typically performed using a "flip chip" method. The "flip chip" hybridization of the optical part onto the electronic part (ROIC) is achieved using indium microbeads, pre-deposited onto the ROIC. Through a thermal cycle, these microbeads are fused, resulting in the interconnection of the two components.
[0086] Thus, according to another aspect, the invention relates to a method for making an optical detector, from the structure obtained with the method 100 according to the invention.
[0087] Method 200 for realizing a DO optical detector corresponds to the first variant, known as individual hybridization. Figure 5 illustrates the diagram of the different steps H1 to L1, and Figure 6 schematically illustrates the technological steps H1 to L1. Method 200 uses the second intermediate substrate SH2 on which the plurality of optical detection circuits is arranged (via bonding), as obtained by method 100.
[0088] The process 200 includes a step H1 consisting of arranging a plurality of optical detection circuits CD on the second intermediate substrate SH2 as obtained at the end of step G of the process 100.
[0089] In a subsequent step II, the optical detection circuits bonded to the second intermediate substrate SH2 are separated from one another, typically by cutting. The optical detection circuits CD are now individualized. The following operations are therefore performed on each circuit CD independently of the others. For a circuit CD, in a step J1, the surface of the pixels of the circuit CD is processed in preparation for assembly.
[0090] In a step K1, the optical detection circuit CD, bonded to the second intermediate substrate SH2, is assembled by hybridization with a readout circuit CL (also separate). Finally, in a step L1, the second intermediate substrate SH2 is removed. The optical detection circuit CD assembled with a readout circuit CL forms an optical detector DO.
[0091] The advantage of this individual hybridization is that it leads to more precise control of the alignment of the optical detection circuit CD with the reading circuit CL. This approach allows for the correction of misalignment.
[0092] Method 300 for implementing a DO optical detector corresponds to the second variant, known as collective hybridization. Figure 7 illustrates the diagram of the different steps H2 to L2, and Figure 8 schematically illustrates the corresponding technological steps. Method 300 uses the second intermediate substrate SH2 on which the plurality of optical detection circuits is arranged (via bonding), as obtained by method 100.
[0093] The process 300 includes a step H2 consisting of a plurality of optical detection circuits CD arranged on the second intermediate substrate SH2 as obtained at the end of step G of the process 100.
[0094] In step 12, the surface of the pixels of the plurality of optical detection circuits is collectively processed in preparation for assembly. The processing is of the same type as that described for step JL
[0095] In a step J2, the plurality of optical circuits DO is assembled by hybridization with a plurality of associated readout circuits CL implemented on a common substrate SUBcl. This hybridization is thus carried out on all the DO circuits simultaneously since they are still connected to each other via the substrate SH2.
[0096] In a step K2, the second intermediate substrate SH2 is removed. Finally, in a step L2, the optical detection circuits assembled with the associated reading circuits are separated from each other, typically by cutting. This yields several optical detectors DO in parallel, each formed by assembling an optical detection circuit CD with a reading circuit CL.
[0097] The advantage of collective hybridization is a saving of time and a reduction in cost due to a single deferral step.
[0098] Processes 200 and 300 thus enable the collective fabrication of optical detectors with metasurfaces. Process 200 only fabricates the metasurfaces collectively, while the hybridization is performed individually. Process 300 fabricates both the metasurfaces and the hybridization collectively.
[0099] Steps C and F of temporary bonding, also referred to as "bonding," and the steps of debonding, also referred to as "removal," can be carried out according to different physical principles combining a bonding material and an associated physical debonding effect. Debonding can be achieved using light (e.g., a laser), heat, or mechanically.
[0100] In addition, according to one embodiment, the temporary bonding can be specifically located on the sample.
[0101] According to a variant of the method for manufacturing a plurality of optical detection circuits, the temporary bonding steps C and F are implemented with a photosensitive polymer.
[0102] In the process according to the invention there are two steps of bonding two host substrates SH1 and SH2 and it must be possible to selectively detach one host substrate at a given time without detaching the other host substrate.
[0103] To this end, according to one embodiment, the bonding of the first intermediate substrate SH1 in step C is carried out with a first polymer PPS1 sensitive in a first spectral band AX1, and the bonding of the second intermediate substrate SH2 in step F is carried out with a second polymer PPS2 sensitive in a second spectral band AX2 different from AX1. It is important that AX2 does not completely overlap AX1: the two spectral bands AX1 and AX2 must each have a portion not included in the other spectral band.
[0104] In this way, according to an embodiment of process 100, step G of removing the first intermediate substrate SH1 is carried out by peeling with a first laser beam FL1 having a first wavelength XI within the first spectral band AX1 and not within the second spectral band AX2. For this, the first intermediate substrate SH1 must be transparent to the first wavelength XL. Indeed, the illumination of PPS1 for peeling is carried out through SH1. Since the polymer PPS2 is not sensitive to XI, the second intermediate substrate SH2 is not peeled.
[0105] According to an embodiment of the methods 200 and 300 of the invention, the respective steps L1 or K2 of removing the second intermediate substrate SH2 are carried out by peeling with a second laser beam FL2 having a second wavelength X2 included in the second spectral band AX2 and not included in AX1. The second intermediate substrate SH2 is transparent to the second wavelength X2 because the peeling is carried out with FL2 through SH2.
[0106] Thanks to the differences in spectral sensitivity range of the two polymers used and a judicious choice of XI and X2, the "debonding" can be carried out selectively.
[0107] In addition, laser “debonding” has the advantage of not causing a temperature rise that is detrimental to the circuits.
[0108] An example of the implementation of "bonding / debonding" with a photosensitive polymer detached by laser is proposed by the company EVG.
[0109] When the SH1 and SH2 substrates are detached, the surfaces should be thoroughly cleaned (pixel side for SH1 and metasurface side for SH2) to remove the residual polymer. A difficulty arises with the metasurface side, due to the small microstructures in which residual polymer could prove challenging to remove.
[0110] According to one embodiment, made possible by the (polymer laser) couple, the polymer can be selectively positioned outside the area in which the microstructures (metasurfaces) are etched, and the laser allows for selective detachment by illuminating only the areas in which the polymer is located: the second polymer PPS2 has been positioned in areas located outside the metasurfaces MS, and the second laser beam performing the detachment in step L1 or step K2 is directed so as to illuminate said areas. This avoids filling the areas between the microstructures.
[0111] The industrial application targeted by processes 100, 200, and 300 according to the invention is the collective fabrication of hybrid circuits with metasurfaces on the back side. Generally, these fabrication processes are applicable to all types of sensing circuits mounted on their reading circuit, with optical, micron, or submicron functionalization of their collecting (illuminated) side. These fabrication methods are directly integrated into an existing conventional process for manufacturing hybrid circuits without metasurfaces.
Claims
1. Demands Method (100) for manufacturing a plurality of optical detection circuits (OCs), said optical detection circuits being intended to be assembled with readout circuits (LCs) to form optical detectors, and being configured to detect an incident optical wave comprising a wavelength (X0) called the operating wavelength, the method comprising the steps of: Having an initial substrate (SUB) common to said plurality of circuits, made of III-V semiconductor material (Mat), having a front face (FAV) on which is arranged a plurality of assemblies (Ens) of pixels (Pix) and a rear face (FAR), a pixel being configured to convert a detected optical wave into an electrical signal, B. to make alignment holes (HO) on said front face having a depth (d) called reference depth between 5 and 50 pm, C transfers a first intermediate substrate (SH1) onto the front face of the initial substrate (SUB) by gluing, To thin the rear face of the initial substrate until reaching the bottom of said alignment holes, said initial substrate then having a thickness equal to said reference depth and being called the thinned substrate, To collectively realize, for the plurality of pixel sets, a structuring of the back face so as to realize a plurality of associated metasurfaces (MS), a metasurface comprising microstructures having a dimension less than or equal to said operating wavelength (X0), a set of microstructures being associated with a pixel, arranged with respect to said pixel in a predetermined manner and configured to modify the incident optical background on said associated pixel, F. Transfer a second intermediate substrate (SH2) onto the structured rear face by bonding. G remove the first intermediate substrate, each pixel set of the plurality of pixel sets, arranged on a fraction of the thinned substrate and presenting a back face on which an associated metasurface is made, forming an optical detection circuit (CD).
2. Method (100) of manufacturing a plurality of optical detection circuits (CD) according to claim 1 wherein the bonding steps C and F are carried out with a photosensitive polymer.
3. A method (100) for manufacturing a plurality of optical detection circuits (CDs) according to the preceding claim wherein the bonding of the first intermediate substrate (SH1) in step C is carried out with a first sensitive polymer in a first spectral band (AX1), and the bonding of the second intermediate substrate (SH2) in step F is carried out with a second sensitive polymer in a second spectral band (AX2) different from the first spectral band.
4. Method (100) of manufacturing a plurality of optical detection circuits (CD) according to the preceding claim wherein the step G of removing the first intermediate substrate (SH1) is carried out by peeling with a first laser beam having a first wavelength (XI) included in the first spectral band and not included in the second spectral band, the first intermediate substrate (SH1) being transparent to said first wavelength (XI).
5. Method (100) of manufacturing a plurality of optical detection circuits (CD) according to any one of the preceding claims wherein the first and / or second intermediate substrate are made of glass or silicon.
6. Method (200) of making an optical detector (OD) comprising the steps of: H1 arranging a plurality of optical detection circuits (OD) on the second intermediate substrate as obtained at the end of step G of the method according to any one of claims 1 to 5, L1 separating said optical detection circuits glued to said second intermediate substrate from each other, J1 for an optical detection circuit, treating a surface of the pixels of said optical detection circuit in preparation for an assembly, K1 assembling by hybridization said optical detection circuit (OD) glued to said second intermediate substrate with a readout circuit (LC), L1 removing the second intermediate substrate, an optical detection circuit (OD) assembled with a readout circuit (LC) forming an optical detector (OD).
7. A method (300) for making an optical detector (OD) comprising the steps of: H2 having a plurality of optical detection circuits arranged on the second intermediate substrate as obtained at the end of step G of the method according to any one of claims 1 to 5, 12 collectively treating a surface of the pixels of the plurality of optical detection circuits, in preparation for an assembly, J2 assembling by hybridization said plurality of optical circuits with a plurality of associated readout circuits (LC) made on a common substrate, K2 removing the second intermediate substrate, L2 separating said optical detection circuits assembled with said associated readout circuits from each other, an optical detection circuit (CD) assembled with a readout circuit (LC) forming an optical detector (OD).
8. Method (200, 300) of making an optical detector (OD) according to any one of claims 6 or 7 wherein the bonding of the second intermediate substrate (SH2) has been carried out with a second polymer sensitive in a second spectral band (AX2), and wherein the step L1 or the step K2 of removal of the second intermediate substrate (SH2) is carried out by peeling with a second laser beam having a second wavelength (X2) included in the second spectral band and not included in the first spectral band, the second intermediate substrate (SH2) being transparent to said second wavelength (X2).
9. Method (200, 300) of making an optical detector (OD) according to the preceding claim wherein in step F the second polymer has been positioned in localized areas outside the metasurfaces, and wherein the second laser beam operating the take-off in step L1 or in step K2 is oriented so as to illuminate said areas.