Fully-integrated multicolor visible light detector based on sub-wavelength polycrystalline silicon grating and preparation method of fully-integrated multicolor visible light detector

Abstract

The invention belongs to the technical field of visible light detection, and aims to realize accurate detection of multicolor visible light and monolithic integration of a multi-wavelength receiver. The invention provides a fully-integrated multicolor visible light detector based on a sub-wavelength polycrystalline silicon grating, which comprises three detectors capable of selectively detecting blue, green and red signals respectively. The principle is as follows: a one-dimensional sub-wavelength polycrystalline silicon grating in the multicolor detector is embedded in an upper SiO2 layer and a lower shallow trench isolation region to form a dielectric waveguide structure of which the middle is a high-refractive-index medium and the periphery is a low-refractive-index oxide layer. The period and the grating width of the sub-wavelength grating are changed, so that the incident polarized light and the sub-wavelength periodic structure are strongly coupled to cause a guided-mode resonance effect, and the sub-wavelength grating can be applied to a transmission optical filter. The size and the cost of the multicolor visible light communication system can be effectively reduced, and the data transmission rate of the system is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of photoelectric detectors, and relates to a multi-color light channel separation method for visible light communication; relates to a design method of a sub-wavelength polysilicon filter grating based on a standard process; and relates to a preparation method of the device using a series of standard CMOS process technologies such as oxidation, photolithography, etching, ion implantation, and metallization. BACKGROUND

[0002] In recent years, with the explosive growth of mobile user terminals, traditional radio frequency communication will gradually be difficult to support the exponential growth of mobile data traffic. Under this background, visible light communication (VLC) emerged as the times require. Compared with traditional wireless communication technology, VLC has both lighting and high-speed communication functions, and has the advantages of rich spectrum resources, large system capacity, good security, and no electromagnetic interference. It has great application potential in electromagnetic interference-sensitive, high-information security environment, intelligent transportation, and underwater high-speed communication fields.

[0003] Currently, the research work of VLC technology mainly focuses on improving the data transmission rate and improving the system stability, and usually uses printed circuit boards (PCB) and commercial discrete components to build a VLC transceiver system. Given that the CMOS (Complementary Metal Oxide Semiconductor) integrated circuit process has been widely commercialized, integrated chips have the characteristics of small size, low cost, low power consumption, and high reliability compared with board-level modules. In the process of industrialization of the VLC system, integrated VLC systems have shown great advantages. In order to further reduce the overall size of the VLC system and improve its ease of use and portability, integration is an inevitable trend for future development. The design cost and difficulty of integrated circuits are much higher than those of board-level modules. Currently, the research of VLC dedicated chips in various countries around the world is still in its infancy. Existing chips are suitable for single-color VLC systems (using blue LEDs with yellow phosphor as the light source), and there are few reports on multi-color (MC) VLC dedicated chips (using multi-color chip integrated LEDs as the light source, such as red, green, and blue LEDs). Since each color of light in the MC-VLC system can carry different data streams simultaneously, it can achieve wavelength division multiplexing (WDM), and the communication rate is multiplied compared with single-color systems. In recent years, the research on MC-VLC has been increasing year by year. Therefore, the development of MC-VLC dedicated chips can effectively improve the communication rate of integrated VLC systems, and has important significance.

[0004] To achieve full integration of a VLC receiver, the PD (Distributed Photodetector) at the receiver front end must also be fully integrated. Early research on VLC technology and OEIC optical receivers revealed difficulties in integrating the filter array at the receiver end of multicolor VLC systems. Multicolor LEDs have wider spectra and larger divergence angles, inevitably leading to spectral overlap during communication. Therefore, channel separation is necessary before the MC-VLC receiver to prevent signal crosstalk. Currently, there are two main methods for achieving channel separation in MC-VLC systems. One method is to place a bandpass filter before the PD. However, achieving WDM requires a large number of filters, which hinders system integration and miniaturization. The other method is to use commercial image sensors as optical receiving devices. Traditional image sensors are mostly dye polymers doped on the top layer of the PD. Each image sensor must be fabricated through multiple steps, which is difficult, costly, and prone to interference. Furthermore, organic materials are unstable under high temperatures or prolonged exposure to ultraviolet radiation. Therefore, to achieve effective integration of the receiver in a multi-color VLC system, a more effective technical method needs to be found to design a color light receiver that is more stable, faster, and more compatible with standard integrated circuit processes.

[0005] With the development of integrated circuits, our fabrication processes are becoming increasingly sophisticated, with the smallest process dimensions reaching the subwavelength level. Subwavelength gratings of specific sizes selectively transmit light of specific wavelengths. Based on standard CMOS processes, we propose a subwavelength grating detector based on standard technology. This allows a multi-wavelength detector based on visible light to be fabricated entirely using standard processes, reducing system size and cost, while also enabling accurate detection of multi-wavelength signals. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, this invention proposes a fully integrated multicolor visible light detector based on a subwavelength polycrystalline silicon grating. This detector is more stable, faster, and effectively compatible with standard integrated circuit processes. It is expected to realize the monolithic integration of multi-wavelength receivers, enabling simultaneous detection of multiple wavelengths in visible light communication and greatly improving the communication bandwidth of visible light communication.

[0007] The present invention adopts the following technical solution: a fully integrated multicolor visible light detector based on a subwavelength polycrystalline silicon grating, wherein the multicolor visible light photodetector includes three detectors: a blue light detector (PDb), a green light detector (PDg), and a red light detector (PDr) to achieve selective detection of blue, green, and red signals.

[0008] The PDb and PDg have similar structures. They include a P-type substrate with a deep N-well region embedded on it. An external active region of the P-type substrate is embedded within the P-type substrate, surrounding the outer periphery of the deep N-well region and adjacent to its upper surface. A P-well region is embedded within the deep N-well region. An external active region of the deep N-well region is embedded within the deep N-well region, adjacent to its upper surface and surrounding it. An external active region of the P-well region is also embedded within the P-well region, adjacent to its upper surface. A shallow trench isolation oxide (STI) layer is embedded at the center of the P-well region. A set of subwavelength periodic one-dimensional gratings made of polycrystalline silicon is arranged directly above the STI layer. An external ground electrode is led out from the external active region of the P-type substrate, and this electrode is grounded. An external electrode of the deep N-well region is led out from the external active region of the deep N-well region, corresponding to the cathodes of the PDb and PDg detectors. The active region connected to the P-well region is led out with an external electrode corresponding to the anode of each PDb and PDg detector.

[0009] The PDr includes a P-type substrate with an N-well region embedded therein. An external active region of the P-type substrate is embedded within the P-type substrate, surrounding the outer periphery of the N-well region and adjacent to its upper surface. The external active region of the P-type substrate is located near the upper surface of the N-well region. A shallow trench isolation oxide layer is embedded at the center of the N-well region. A set of subwavelength periodic one-dimensional gratings made of polycrystalline silicon is arranged directly above the STI layer. An external ground electrode is led out corresponding to the external active region of the P-type substrate, corresponding to the anode of each PDr. A deep N-well external electrode is led out corresponding to the external active region of the deep N-well region, corresponding to the cathode of the PDr detector.

[0010] In the design of PDb, PDg, and PDr, the upper metal interconnect layer and passivation layer of the detector are removed, so that there is only a thick intermetallic dielectric (SiO2) on the Si substrate, in order to reduce scattering and allow more light to penetrate into the PD.

[0011] When designing subwavelength polysilicon gratings for PDb, PDg, and PDr, a doping barrier layer should be added to avoid accidental implantation of meaningless doping onto the polysilicon subwavelength grating.

[0012] The subwavelength polysilicon gratings in PDb, PDg, and PDR are embedded in a thick intermetallic dielectric (SiO2), with a shallow channel isolation oxide layer underneath. This forms a structure with a high-refractive-index dielectric grating in the middle and low-refractive-index oxide layers on the capping and substrate. Due to the anomalous diffraction phenomenon that occurs in diffraction gratings under certain grating geometry parameters (subwavelength) and incident conditions, they have great potential for beam splitting. Given that the polysilicon thickness is fixed in standard circuits, the period and grating width of the subwavelength polysilicon grating can be varied. When the subwavelength grating on the planar waveguide satisfies the guided-mode resonance (GMR) condition caused by strong coupling between the incident wavelength and the periodic structure, the subwavelength grating can be used in transmission or reflection filters.

[0013] The incident light detected by PDb, PDg, and PDr is polarized light to achieve better filtering effect, and its polarization direction is parallel to the grating direction. Therefore, when using this detector, a set of filters should be placed in front of the receiver.

[0014] The detector structures in PDb and PDg that detect light filtered through a subwavelength grating are double PN junction photodiodes composed of a P-well / DNW / P-substrate, where the DNW and P-substrate are short-circuited. Therefore, due to the built-in barrier between the P-substrate and DNW, photogenerated electrons and holes in the P-substrate move to the N+ layer in the DNW and the P+ layer in the P-substrate, respectively, and then recombine, which does not contribute to the photocurrent. As a result, only photogenerated carriers generated near the P-well / DNW P-substrate junction contribute to the photocurrent. Since the absorption coefficient and penetration depth of light incident on the material depend on the wavelength, short-wavelength light is absorbed faster near the semiconductor surface, while long-wavelength light penetrates deeper within the semiconductor. Therefore, this structure can reduce the influence of long-wavelength light.

[0015] The detector structure in the PDr that detects light filtered through a subwavelength grating is a photodiode composed of N-well / P-substrate, which has a strong response to long-wavelength light.

[0016] To achieve simultaneous and accurate detection of multiple wavelengths in visible light communication and monolithic integration of a multi-wavelength receiver, this invention proposes a fully integrated multicolor visible light detector based on a subwavelength polycrystalline silicon grating. The beneficial effects of this invention are as follows:

[0017] 1) As the demand for data transmission rates increases, research on VLC systems using multi-color LEDs as light sources has attracted significant attention. However, regarding the full integration of VLC receivers, reported VLC chips are suitable for monochrome systems, and research on dedicated multi-color VLC chips is rare. This invention will further promote the full integration and industrialization of VLC systems, advancing integrated VLC systems from monochrome communication to multi-color communication. Combined with polarizers and RGB-LEDs, the physical links for visible light communication can be increased to 6 channels, greatly improving the data transmission rate of integrated VLC systems.

[0018] 2) The fabrication process of the multi-wavelength photodetector is fully compatible with CMOS electronic circuit technology, enabling monolithic integration of the multi-wavelength photodetector and electronic circuitry on the same chip without incurring any additional costs. By controlling the structural parameters of the polysilicon grating, the photoelectric response can be optimized to achieve the three primary colors, making it an effective way to realize chip-based multi-color visible light receivers. This reduces the use of filters in multi-color visible light communication systems, lowers system size and cost, and improves integration.

[0019] In summary, this invention proposes a novel method for achieving channel separation at the receiver end of a VLC system by combining subwavelength dielectric grating filtering theory with standard CMOS process capabilities, which has promising application prospects. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 is a top view of the structure of the fully integrated multicolor visible light detector based on a subwavelength polycrystalline silicon grating proposed in this invention;

[0022] Figure 2 is a cross-sectional view of the structure of the fully integrated multicolor visible light detector based on a subwavelength polycrystalline silicon grating proposed in this invention.

[0023] Appendix Figure 3 This invention proposes simulated transmission spectrum curves for three subwavelength polycrystalline silicon gratings in a multicolor visible light detector;

[0024] Appendix Figure 4 This invention proposes a photoelectric joint simulation of the spectral response diagram of a multicolor visible light detector. Detailed Implementation

[0025] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] A fully integrated multicolor visible light detector based on a subwavelength polycrystalline silicon grating, comprising three detectors: a blue light detector (PDb), a green light detector (PDg), and a red light detector (PDr) to achieve selective detection of blue, green, and red signals.

[0027] like Figure 1a and Figure 2a As shown, the PDb and PDg have similar structures. Each includes a P-type substrate 1, with a deep N-well region 2 embedded on it. An external active region 6 is embedded within the P-type substrate 1, surrounding the outer periphery of the deep N-well region 2 and adjacent to its upper surface. A P-well region 3 is embedded within the deep N-well region 2, adjacent to its upper surface and surrounding the P-well region 5, with an external active region 5. An external active region 4 is embedded within the P-well region 3, adjacent to its upper surface. An STI layer 5 is located at the center of the P-well region 3. A set of periodic gratings 7 made of polycrystalline silicon is arranged directly above the STI layer 5. An external ground electrode 8 is led out from the external active region 6, and this electrode is grounded. An external deep N-well electrode 10 is led out from the external active region 5, corresponding to the cathode 9 of the PDb and PDg detectors. A P-well external electrode 11 is led out from the active region 4 corresponding to the P-well region, corresponding to each of the detector anodes 12.

[0028] like Figure 1b and Figure 2b As shown, the PDr includes a P-type substrate 1, on which an N-well region 13 is embedded. An external active region 16 of the P-type substrate is embedded within the P-type substrate 1, surrounding the outer periphery of the N-well region 13 and adjacent to the upper surface of the P-type substrate 1. An external active region 14 of the P-type substrate is located near the upper surface of the N-well region 13. An STI (Solid Layer Induction) layer 15 is located at the center of the N-well region 13. A set of periodic gratings 17 made of polycrystalline silicon is arranged directly above the STI layer 15. An external ground electrode 18 is led out corresponding to the external active region 16 of the P-type substrate, corresponding to the anode of each PDr. A deep N-well external electrode 20 is led out corresponding to the external active region 14 of the deep N-well region, corresponding to the cathode 19 of the PDr detector.

[0029] The main technological steps for realizing the photodetector described in this invention include:

[0030] 1) A lightly doped P-type silicon wafer is used to form a P-type silicon substrate 1. Subsequently, low-pressure chemical vapor deposition (LPVCD) of SiN4 is performed.

[0031] 2) After the photoresist is applied to the wafer, the pattern of the N-well region to be formed is defined using photolithography. Then, the SiN4 in the defined region is removed using dry etching to form the N-well and deep N-well implantation windows, namely regions 13 and 2.

[0032] 3) Using ion implantation, N is implanted into the window defined in step 2), then the photoresist is removed using an inorganic solution ablation method; and the SIN is removed using a hot phosphoric acid wet etching method.

[0033] 4) Ion implantation severely disrupts the periodicity of the crystal lattice, so annealing is necessary after ion implantation to restore the integrity of the crystal lattice.

[0034] 5) Spin-coat photoresist to mask the active areas (regions 4, 5, 6, 14, and 16), then expose the entire wafer. Remove the photoresist from the exposed areas to form an oxide layer on the exposed surface, i.e., regions 5 and 15;

[0035] 6) A polycrystalline silicon layer, namely regions 7 and 17, is deposited on the wafer surface using low-pressure chemical vapor deposition (LPCVD) technology;

[0036] 7) Photoresist is applied to the wafer, and then photolithography is used to define the desired polysilicon area. Then, active ion etching is used to etch the polysilicon layer structure, and finally the photoresist on the surface is removed.

[0037] 8) Using oxidation technology, an oxide layer is formed on the wafer surface to protect the device surface from the effects of subsequent processes. After coating with photoresist, the P+ regions of the photodetector, namely regions 4, 6, and 16, are etched using photolithography. Simultaneously, the N+ regions of the photodetector, namely regions 5 and 14, are shielded, and boron is then implanted into regions 4, 6, and 16 using ion implantation technology.

[0038] 9) The N+ region of the photodetector, namely regions 5 and 14, is etched using photolithography. At the same time, the P+ region of the photodetector, namely regions 4, 6 and 16, is shielded. Arsenic is then implanted into regions 5 and 14 using ion implantation technology. Finally, the photoresist on the wafer surface is removed.

[0039] 10) Remove the surface oxides generated in step 8). Then, use annealing to electrically activate and diffuse the ion-implanted N+ and P+ regions.

[0040] 11) Ti is deposited on the entire wafer surface using a sputtering process, followed by the formation of TISi2 using a self-aligned silicide process. Excess Ti is then removed by wet etching, leaving the TISi2 to form an ohmic contact between Si and the metal. Boron phosphosilicate glass (BPSG) is deposited on the entire wafer surface using a sputtering process, and the wafer surface is then chemically and mechanically planarized.

[0041] 12) Other high-layer interconnect metals are prepared using photolithography, etching and metallization processes as anodes and cathodes to draw the photocurrent of the photodetector to the contact pads.

[0042] In the design of PDb, PDg, and PDr, the upper metal interconnect layer and passivation layer of the detector are removed, so that there is only one thick intermetallic dielectric (SiO2)21 on the Si substrate, in order to reduce scattering and allow more light to penetrate into the PD.

[0043] When designing subwavelength polysilicon gratings for PDb, PDg, and PDr, a doping barrier layer should be added to avoid accidental implantation of meaningless doping onto the polysilicon subwavelength grating.

[0044] The subwavelength polysilicon gratings in PDb, PDg, and PDR are embedded in a thick intermetallic dielectric 21, with a shallow channel isolation oxide layer 5 and 15 below. This forms a structure with a high-refractive-index dielectric grating in the middle and a low-refractive-index oxide layer on the capping and substrate. Due to the anomalous diffraction phenomenon that occurs under certain grating geometry parameters (subwavelength) and incident conditions, diffraction gratings have great potential in beam splitting. Given that the polysilicon thickness is fixed in standard circuits, the period and grating width of the subwavelength polysilicon gratings 7 and 17 can be varied. When the subwavelength gratings 7 and 17 on the planar waveguide satisfy the GMR condition caused by the strong coupling between the incident wavelength and the periodic structure, the subwavelength gratings can be used for transmission or reflection filters.

[0045] The incident light detected by PDb, PDg, and PDr is polarized light to achieve better filtering effect, and its polarization direction is parallel to the grating direction. Therefore, when using this detector, a set of filters should be placed in front of the receiver.

[0046] The detector structures in PDb and PDg that detect light filtered through a subwavelength grating are double PN junction photodiodes composed of a P-well / DNW / P-substrate, where the DNW and P-substrate are short-circuited. Therefore, due to the built-in barrier between the P-substrate and DNW, photogenerated electrons and holes in the P-substrate move to the N+ layer in the DNW and the P+ layer in the P-substrate, respectively, and then recombine, which does not contribute to the photocurrent. As a result, only photogenerated carriers generated near the P-well / DNW P-substrate junction contribute to the photocurrent. Since the absorption coefficient and penetration depth of light incident on the material depend on the wavelength, short-wavelength light is absorbed faster near the semiconductor surface, while long-wavelength light penetrates deeper within the semiconductor. Therefore, this structure can reduce the influence of long-wavelength light.

[0047] The detector structure in the PDr that detects light filtered through a subwavelength grating is a photodiode composed of N-well / P-substrate, which has a strong response to long-wavelength light.

[0048] Example:

[0049] Figure 3 The simulated transmission spectrum curves of three subwavelength polysilicon gratings in a multicolor visible light detector designed based on TSMC 40 standard process are shown. The polysilicon layer and STI thickness are constant, approximately 80 nm and 320 nm, respectively. Therefore, the transmission spectrum of the three-color filter is determined by its structural parameters, namely the grating period (π) and grating width (Wg). In the three-primary-color PD, the π / Wg values ​​of the three designed polysilicon subwavelength gratings are 290 nm / 100 nm (PDb), 210 nm / 60 nm (PDg), and 350 nm / 200 nm (PDr), respectively. It can be seen that the subwavelength gratings can achieve a relatively good spectrally selective transmission effect.

[0050] Figure 4 The figure shows the output spectral response (solid line) of a photodiode detecting the light signal transmitted by a grating under a subwavelength grating in a photoelectric co-simulation. It can be seen from the figure that compared with the grating transmission spectrum (dashed line), selecting a suitable photodiode can further optimize the output effect of the color photodetector.

[0051] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A fully integrated multicolor visible light detector based on a subwavelength polycrystalline silicon grating, characterized in that, It includes three detectors: a blue light detector (PDb), a green light detector (PDg), and a red light detector (PDr) to achieve selective detection of blue, green, and red signals. The PDb and PDg have similar structures. Each includes a P-type substrate (1) with a deep N-well region (2) embedded therein. An external active region (6) is embedded within the P-type substrate (1) surrounding the outer periphery of the deep N-well region (2) and adjacent to the upper surface of the P-type substrate (1). A P-well region (3) is embedded within the deep N-well region (2). An external active region (5) is embedded within the deep N-well region (2) adjacent to the upper surface and surrounding the P-well region (3). External active regions (4) are embedded on both sides of the P-well region (3) adjacent to the upper surface. A shallow trench isolation region oxide (STI) layer (5) is embedded at the center of the P-well region (3). A set of one-dimensional periodic gratings (7) made of polycrystalline silicon is arranged directly above the STI layer (5). An external ground electrode (8) is led out from the external active region (6) of the P-type substrate, and this electrode is grounded. A deep N-well external electrode (10) is led out from the external active region (5) corresponding to the deep N-well region, which corresponds to the cathode (9) of the PD1 and PD2 detectors. A P-well external electrode (11) is led out from the external active region (4) corresponding to the P-well region, which corresponds to the anode (12) of each detector. The PDr includes a P-type substrate (1) with an N-well region (13) embedded thereon. An external active region (16) is embedded within the P-type substrate (1) surrounding the outer periphery of the N-well region (13) and adjacent to the upper surface of the P-type substrate (1). An external active region (14) is located within the N-well region (13) adjacent to its upper surface. A shallow trench isolation region oxide (STI) layer (15) is embedded at the center of the N-well region (13). A set of one-dimensional periodic gratings (17) made of polycrystalline silicon is arranged directly above the STI layer (15). An external ground electrode (18) is led out from the external active region (16) of the P-type substrate, corresponding to the anode of each detector. A deep N-well external electrode (20) is led out from the external active region (14) of the deep N-well region, corresponding to the cathode (19) of the detector.

2. According to claim 1, in the design of PDb, PDg and PDr, the upper metal interconnect layer and passivation layer of the detector are removed, so that there is only one thick intermetallic dielectric (SiO2) on the Si substrate (21) to reduce scattering and allow more light to enter the PD.

3. According to claim 1, when designing subwavelength polysilicon gratings such as PDb, PDg, and PDR, a doping barrier layer should be added to avoid the accidental implantation of meaningless doping on the subwavelength polysilicon grating.

4. According to claim 1, the subwavelength polycrystalline silicon gratings (7) and (17) in PDb, PDg, and PDR are embedded in a thick intermetallic dielectric (21), with a shallow channel isolation region oxide layer (5) and (15) below. This forms a dielectric grating with a high refractive index in the middle and a low refractive index oxide layer structure for the capping layer and substrate. Due to the anomalous diffraction phenomenon that occurs in diffraction gratings under certain grating geometric parameters (subwavelength) and incident conditions, it has great potential in beam splitting. By changing the period and grating width of the subwavelength polycrystalline silicon grating, when the subwavelength grating on the planar waveguide satisfies the guided mode resonance condition caused by the strong coupling between the incident wavelength and the periodic structure, the subwavelength grating can be applied to transmission or reflection filters.

5. As described in claim 1, the incident light detected by PDb, PDg, and PDr is linearly polarized light to achieve a better filtering effect. Its polarization direction is parallel to the grating direction. Therefore, when using this detector, a set of filters should be placed in front of the receiving end.

6. According to claim 1, the detector structure in PDb and PDg that detects light filtered through a subwavelength grating is a double PN junction photodiode composed of P-well / DNW / P-substrate, wherein DNW and P-substrate are short-circuited. Therefore, due to the built-in barrier between P-substrate and DNW, photogenerated electrons and holes in P-substrate move to the N+ layer in DNW and the P+ layer in P-substrate, respectively, and then recombine, which does not contribute to the photocurrent. As a result, only photogenerated carriers generated near the P-well / DNW P-substrate junction contribute to the photocurrent. Thus, this structure can reduce the influence of long-wavelength light. According to claim 1, the detector structure in PDr that detects light filtered through a subwavelength grating is a photodiode composed of N-well / P-substrate, which has a strong response to long-wavelength light.

7. An embodiment based on the TSMC 40 standard process design according to claim 1. In the three-color PD, the period / gate width values ​​of the three designed polysilicon subwavelength gratings are 290nm / 100nm (PDb), 210nm / 60nm (PDg), and 350nm / 200nm (PDr), respectively.

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