Long-wave-pass optical filter and integrated device

Abstract

The utility model provides a long wave pass optical filter and an integrated device, the film system structure of the optical filter is G / 0.5 H (LH) mL0.5 H / A, G is a substrate, H is a high refractive index film with a quarter wavelength thickness, L is a low refractive index film with a quarter wavelength thickness, m is a periodicity, and A is an air medium; the low-refractive-index film is a silicon oxide film; and the high-refractive-index film is an oxygen-doped germanium film. The integrated device comprises a silicon substrate, a fluorescence detection unit, a silicon oxide spacer layer and a long-wave-pass filtering film system, a fluorescence detection unit is arranged on the silicon substrate, and a silicon oxide spacing layer and a long-wave-pass filtering film system are sequentially arranged on the surface of the fluorescence detection unit; the thickness of the silicon oxide spacing layer is greater than the peak wavelength of the photon detection efficiency of the fluorescence detection unit. The film system structure of the long-wave-pass optical filter is simpler than that of a traditional band-pass filtering film system, the preparation process can be simplified, and the long-wave-pass optical filter is more suitable for process integration and process compatibility with other optoelectronic components.

Description

Technical Field

[0001] This application relates to the field of semiconductor optoelectronics and its applications, and particularly relates to a long-wave pass filter and an integrated device. Background Art

[0002] For fluorescence detection, it is usually required to use an excitation light source with a short wavelength (e.g., below 600 nm) to excite fluorescent molecules to emit fluorescence. Then, a highly sensitive photomultiplier tube or a CMOS image sensor is used to detect the fluorescence for quantitative analysis or imaging of the fluorescence. Since the light intensity of the excitation light source used to excite the fluorescent molecules is usually much higher than the fluorescence emitted by the fluorescent molecules, if the photomultiplier tube is directly used to detect the fluorescence, the optical signal of the fluorescent molecules will be completely covered by the excitation light source. Therefore, before the light reaches the photomultiplier tube, it is usually necessary to filter out the short-wave excitation light source so that the photomultiplier tube can only detect the fluorescence, or the light intensity of the detected fluorescence is much higher than that of the excitation light source filtered by the filter film.

[0003] For a traditional band-pass filter film system with a low absorption coefficient, if it is required to have a high optical density value for a specific wavelength excitation light source, it usually needs to use a filter film with the number of film layers close to 100 layers or more, and the film layer structure usually contains multiple optical cavity structures and phase matching layers between each optical cavity structure. In this way, the film system structure will be too complex, and it is difficult to complete the growth of the film system structure using common semiconductor thin film processes, that is, the complex film system structure brings more difficulties to the preparation process and the integration with other devices.

[0004] Ideally, for a long-wave pass film system, the requirements for the refractive index value and the extinction coefficient change trend of a high refractive index material are that both decrease monotonically with the increase of wavelength. However, usually, the refractive index value and the extinction coefficient value of a high refractive index material usually have peaks, which results in that in the short-wave direction of the peak, the refractive index value and the extinction coefficient value increase monotonically, while in the long-wave direction of the peak, the refractive index value and the extinction coefficient value decrease monotonically. For example, the refractive index peak of TiO 2 is near 315 nm, the refractive index peak of crystalline silicon is between 350 - 400 nm, and the refractive index peaks of carbon-doped amorphous silicon thin film and nitrogen-doped amorphous silicon thin film are also in this range. Therefore, some people propose to prepare a long-wave pass filter film system by matching a carbon-doped amorphous silicon thin film with a high refractive index value and a high extinction coefficient value with a silicon dioxide thin film, which can achieve a high optical density value for a specific band with fewer film layers.

[0005] However, the above long-wave pass filter film system also has some deficiencies: for example, the refractive index peak of amorphous silicon is generally between 350 nm and 400 nm, so the cut-on wavelength of the long-wave pass filter film obtained by this system is generally also near this band, and its application range is limited and it cannot be well applied to longer bands; in addition, carbon-doped amorphous silicon is usually prepared by the PECVD (plasma-enhanced chemical vapor deposition) process, and the rate is slow. In addition, due to the continuous alternating growth of multi-layer optical thin films, it is easy to contaminate the PECVD reaction chamber, increasing the frequency and frequency of equipment maintenance. Therefore, it is necessary to provide a new long-wave pass filter film system structure so that it can be applicable to the case where the cut-on band is in a longer band, and at the same time improve the preparation process to make the preparation more convenient and fast.

[0006] It should be noted that the above introduction of the technical background is only for the convenience of clearly and completely explaining the technical solutions of the present application and facilitating the understanding of those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art just because these solutions are described in the background art part of the present application. Summary of the Invention

[0007] The present invention provides a long-wave pass filter and an integrated device to solve all or part of the above-mentioned existing technical problems, so as to obtain a filter with a simpler film layer structure and an integrated device for fluorescence detection, and the preparation of this film system structure is simple, and the integration of optical thin films and detection devices can be completed without using a professional optical coating machine.

[0008] The present invention uses an oxygen-doped germanium thin film material with high refractive index, high extinction coefficient and high dispersion effect and a silicon oxide thin film (SiO 2The (thin film) material constructs a long-wave pass filter film system structure. On the one hand, the two materials have a large refractive index difference, and a relatively wide high-reflection band with a high reflectivity value can be formed in the band centered on the central wavelength with fewer periods; on the other hand, the oxygen-doped germanium thin film has a high extinction coefficient value in the short wave, and the extinction coefficient value has a large gradient from ultraviolet to visible light and near infrared. Thus, in the short-wave range, due to the high absorption of the oxygen-doped germanium thin film and the effect of the high-reflection band, a higher blocking of short-wave photons can be formed; while in the long-wave band, since the absorption coefficients of the two materials are almost 0, it is easy to form a passband with a higher transmittance. Coupled with the use of the long-wave pass film layer structure, the first-order oscillation of the transmittance in the passband region can be suppressed to a certain extent. Moreover, due to the influence of the high absorption coefficient of the oxygen-doped germanium thin film and the non-use of an optical cavity in the film system structure, the transmission spectrum is not very sensitive to the change of the incident light incident angle whether it is in the p-polarization state or the s-polarization state. Therefore, for fluorescence detection with a relatively wide emission spectrum, compared with the traditional band-pass filter film system, while achieving the same or better optical characteristics, the long-wave pass filter film system in this application can make the film layer structure simpler and easier to grow, and is also more suitable for process integration and process compatibility with other optoelectronic components.

[0009] To achieve the above object, the present utility model provides a long-wave pass filter film, and the film system structure of the filter film is: G / 0.5H(LH) m L0.5H / A, where G represents the substrate, H represents a high-refractive-index thin film with an optical thickness of one-quarter of the central wavelength, L represents a low-refractive-index thin film with an optical thickness of one-quarter of the central wavelength, m represents the number of periods, and A represents the air medium; the low-refractive-index thin film is a silicon oxide thin film; the high-refractive-index thin film is an oxygen-doped germanium thin film. A new film system structure is provided. By using a high-extinction thin film material and not using an optical cavity in the film system structure, the band-pass region is not obvious to the incident light angle. In addition, the film system structure of the present invention is simpler than the traditional band-pass filter film system structure. By using only a few film layers, the same or better effect can be achieved, which is beneficial to simplifying the preparation process and process integration and process compatibility with other optoelectronic components.

[0010] The number of periods m is more than 2. Increasing the number of periods can increase the optical density value of the filter film in the short-wave direction, but it will also reduce the transmittance in the long-wave region. Therefore, an appropriate number of periods should be selected so that the optical density value in the blocking region and the average transmittance in the passband region are both within an acceptable range.

[0011] The film system structure of the filter film is: G / 0.5H(LH) 20 L0.5H / A. This film system structure design can obtain an ideal band-pass range. By using an oxygen-doped germanium thin film and SiO with a relatively high refractive index value and a relatively high extinction coefficient value2 A long-wave pass filter film system is prepared by using a thin film, so that a high optical density value (OD>5) can be achieved for specific excitation light with a relatively small number of film layers (about 40 layers).

[0012] An integrated device includes: a silicon substrate, a fluorescence detection unit, a silicon oxide spacer layer, and a long-wave pass filter film system; the fluorescence detection unit is disposed on the silicon substrate, and the silicon oxide spacer layer and the long-wave pass filter film system are sequentially disposed on the surface of the fluorescence detection unit; the thickness of the silicon oxide spacer layer is greater than the peak wavelength of the photon detection efficiency of the fluorescence detection unit; the structure of the long-wave pass filter film system is 0.5H(LH) m L0.5H, where H represents a high refractive index thin film with an optical thickness of one-quarter of the central wavelength, L represents a low refractive index thin film with an optical thickness of one-quarter of the central wavelength, and m represents the number of periods; the low refractive index thin film is a silicon oxide thin film; the high refractive index thin film is an oxygen-doped germanium thin film. The long-wave pass filter film system provided by the present application has a relatively simple film layer structure, a relatively small number of film layers, and a relatively small total thickness of the film layers, and is very suitable for integration with optoelectronic components such as photomultiplier tubes and CMOS image sensors to achieve better fluorescence detection performance.

[0013] The fluorescence detection unit is at least one. When there are multiple fluorescence detection units, the multiple fluorescence detection units are arranged on the silicon substrate in an array form.

[0014] A protective layer is disposed on the surface of the long-wave pass filter film system, which can protect the filter film from being damaged.

[0015] The fluorescence detection unit is a photomultiplier tube, and multiple photomultiplier tubes are arranged on the silicon substrate in an array form.

[0016] The thickness of the silicon oxide spacer layer is more than 2um, which is used to ensure that the thickness of the silicon oxide spacer layer is greater than the peak wavelength of the photon detection efficiency of the photomultiplier tube, so as to ensure the normal operation of the long-wave pass filter film system and the photomultiplier tube.

[0017] The structure of the long-wave pass filter film system is 0.5H(LH) 20 L0.5H. This film system structure design can obtain an ideal passband range, and then obtain better fluorescence detection performance.

[0018] Compared with the prior art, the beneficial effects of the present utility model mainly include the following: The present utility model provides a long-wave pass filter and an integrated device. By providing a new film system structure, through the use of high extinction thin film materials and the non-use of optical cavities in the film system structure, the passband region is not obvious to the incident light angle; in addition, the film system structure of the present utility model is simpler than the traditional band-pass filter film system structure. By using only a few film layers, the same or better effects can be achieved, which is beneficial to simplifying the preparation process and the process integration and process compatibility with other optoelectronic components. Brief Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions in the specific embodiments of the present utility model, the following will briefly introduce the drawings required for use in the description of the embodiments. Obviously, the following described drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0020] Figure 1 Schematic diagram of the film layer structure of a long-wave pass filter provided in Embodiment 1 of the present utility model.

[0021] Figure 2 Refractive index values of germanium, germanium oxide, and silicon oxide materials.

[0022] Figure 3 Extinction coefficient values of germanium, germanium oxide, and silicon oxide materials.

[0023] Figure 4 Refractive index values of germanium, oxygen-doped germanium with different oxygen doping amounts, and germanium oxide materials.

[0024] Figure 5 Extinction coefficient values of germanium, oxygen-doped germanium with different oxygen doping amounts, and germanium oxide materials.

[0025] Figure 6 Reflectance, transmittance, and absorbance values of a long-wave pass filter provided in Embodiment 1 of the present utility model.

[0026] Figure 7 Optical density value of a long-wave pass filter provided in Embodiment 1 of the present utility model.

[0027] Figure 8 Results of the reflection spectrum, transmission spectrum, and absorption spectrum of a long-wave pass filter provided in Embodiment 2 of the present utility model.

[0028] Figure 9 Schematic diagram of the structure of an integrated device with a long-wave pass filter film system provided in Embodiment 3 of the present utility model. Detailed Description of the Embodiments

[0029] The foregoing and other technical contents, features and effects of the present utility model will be clearly presented in the following detailed description of a preferred embodiment in conjunction with the accompanying drawings. The directional terms mentioned in the following embodiments, such as: up, down, left, right, front or back, etc., are only with reference to the directions of the attached drawings. Therefore, the directional terms used are for illustration and not for limiting the present utility model.

[0030] The following will elaborate on each embodiment of the present application in conjunction with the accompanying drawings. However, those of ordinary skill in the art can understand that in each embodiment of the present application, many technical details are provided for readers to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present application can still be implemented.

[0031] Embodiment 1:

[0032] In this embodiment, taking the oxygen-doped germanium / silicon oxide (SiO 2 ) thin film material with a central wavelength of 400 nm as an example, a long-wave pass filter film system structure is introduced.

[0033] Figure 1 It is a schematic diagram of the film layer structure of a long-wave pass filter provided in Embodiment 1 of the present utility model.

[0034] As Figure 1 shown, a long-wave pass filter includes: a substrate 1, and an oxygen-doped germanium and silicon oxide thin film 31. In this embodiment, the oxygen-doped germanium thin film and the silicon oxide thin film 31 are alternately arranged on the substrate 1 in sequence; in other embodiments, the substrate 1 can be a glass substrate or a silicon substrate.

[0035] As Figure 1 shown, the film layer structure of the long-wave pass filter can be expressed as: G / 0.5H(LH) m L0.5H / A. In this embodiment, G represents the substrate 1, A represents the air environment; H is an oxygen-doped germanium thin film with an optical thickness of one-quarter of the central wavelength, and this thin film material has a high refractive index, a high extinction coefficient and a strong dispersion effect, and the refractive index and extinction coefficient of the material can be adjusted according to the amount of oxygen doping; L is a silicon oxide thin film 31 with an optical thickness of one-quarter of the central wavelength, and this thin film material has a low refractive index, a low extinction coefficient and a weak dispersion effect; m represents the number of periods.

[0036] In this embodiment, the selected central wavelength is 400nm, H represents an oxygen-doped germanium film with an optical thickness of one quarter of the central wavelength, 0.5H represents an oxygen-doped germanium film with an optical thickness of one eighth of the central wavelength, and L represents a thickness of each layer of silicon oxide film 31 of one quarter of the central wavelength. Wherein, the oxygen doping amount of the oxygen-doped germanium film is 10%, then the thickness of H is 61nm, and the thickness of L is 76nm. Generally, the thickness deviation of the film layer is acceptable within 5%.

[0037] In this embodiment, the number of cycles m is 20. Figure 1 As shown in the figure (the number of film layers in the figure is for illustration only, not the actual number of film layers in this embodiment), that is, on a smooth substrate 1, firstly, a layer of oxygen-doped germanium film 2 with a thickness of eight-wavelength is stacked; then, a silicon oxide film 31 with a thickness of four-wavelength and an oxygen-doped germanium film 32 with a thickness of four-wavelength are alternately arranged, and the two are alternately stacked 20 times continuously to form a silicon oxide film 31, thereby forming a periodic structure 3 (i.e. (LH) 20 L structure). Finally, a layer of oxygen-doped germanium film 4 with a thickness of one-eighth wavelength is stacked on the surface of the periodic structure 3 (i.e., the silicon oxide film 31), and finally a structure as shown in FIG. Figure 1 In this embodiment, the periodic structure 3 shows that the silicon oxide film 31 / oxygen-doped germanium film 32 structure is repeated 20 times, with a total of 40 layers, and a silicon oxide film 31 is further disposed thereon.

[0038] In the film structure, the period number m can be determined according to the specific optical density value requirements and long-wave transmittance requirements, based on the refractive index value and extinction coefficient value of the material of the high refractive index layer used. In other embodiments, the value of m is generally at least greater than or equal to 2. Generally, when the film material remains unchanged, the greater the period number of the film structure, the greater the optical density value of the obtained long-wave pass filter in the short-wave range. However, an increase in the period number will also lead to a corresponding decrease in the transmittance of the filter in the passband region. Therefore, according to different situations, it is necessary to select an appropriate period number so that the optical density value of the blocking area and the average transmittance of the passband area are both within the design range.

[0039] It should be noted that the G / 0.5H(LH) used in this embodiment 20 The L0.5H / A structure is designed in a certain way according to the central wavelength (400nm) selected in this embodiment and the refractive index of the materials used for the oxygen-doped germanium film and the silicon oxide film 31. It is not necessary to use G / 0.5H (LH). 20 L0.5H / A structure.

[0040] G / 0.5H(LH) used in this embodiment 20The specific design process of the L0.5H / A structure is as follows: First, confirm the refractive index values and extinction coefficient values of a series of oxygen-doped germanium monolayer films with different oxygen contents to select a better oxygen-doped germanium film; then, through the analysis of the refractive index change trend and extinction coefficient change trend of the oxygen-doped germanium film material, select the central wavelength and design a corresponding film system structure as the input for thin-film optical calculation; finally, calculate and output the results, and perform iteration until the output spectral characteristics reach the target, then the corresponding oxygen-doped germanium film material and film system structure can be selected for growth. Specifically, it is described as follows.

[0041] Figure 2 Shows the refractive index values of germanium (Ge), germanium oxide (GeO), and silicon dioxide (SiO 2 ) films. Ge has very similar properties to Si and has a very high refractive index (between 4 and 6) within a very wide wavelength range (300 nm to 1000 nm). The difference is that Ge has a peak refractive index value at 600 nm. GeO and SiO 2 are more similar. Between 300 nm and 1000 nm, the refractive index is almost not much different from that of SiO 2 and does not fluctuate much with the change of wavelength.

[0042] Figure 3 Are the extinction coefficient values of germanium (Ge), germanium oxide (GeO), and silicon dioxide (SiO 2 ) films. Compared with Si, the extinction coefficient of Ge is also generally similar, but it also shows some different characteristics. Since 300 nm, the extinction coefficient value of germanium starts to decrease from 3.8, but it is not completely monotonically decreasing. Near 520 nm, a peak close to 2.5 appears. Then, from here to 1000 nm, it has been monotonically decreasing until about 0.2. The extinction coefficients of germanium oxide and silicon dioxide are much lower than that of germanium and are both close to 0 (as shown in the local enlarged view on the right in Figure 3 , the extinction coefficient values of germanium oxide and silicon dioxide are below 0.005, far less than the extinction coefficient of germanium).

[0043] According to Figure 2 and Figure 3 , it can be seen that the refractive index and extinction coefficient of oxygen-doped germanium can be tuned in the region between Ge and GeO by doping O into Ge, and then a long-wave pass filter film based on oxygen-doped germanium / silicon dioxide material can be realized. The effective refractive index and extinction coefficient of the oxygen-doped germanium material can be simply estimated by the ratio of Ge and GeO in the thin film. If more accurate results are required, they can also be measured by testing equipment. From Figure 2 and Figure 3It can be seen that based on the characteristics of the refractive index value and extinction coefficient value of Ge materials, compared with the silicon system, it is more suitable for obtaining long-wave pass filter films with opening bands more biased towards the long wave. In addition, carbon-doped amorphous silicon thin films are usually prepared by the PECVD process, while oxygen-doped germanium thin films can be prepared by the PVD (physical vapor deposition) process. On the one hand, the PVD process for preparing thin films can obtain a faster rate. On the other hand, the PVD process also has a certain anti-pollution function. From the perspective of the preparation process, the oxygen-doped germanium / silicon dioxide system also has certain advantages. In addition, other material systems, such as GaP / SiO 2 or TiO 2 / SiO 2 etc. can also be realized, which will not be elaborated here.

[0044] As Figure 4 and Figure 5 shown, they are respectively the refractive index and extinction coefficient results of oxygen-doped germanium materials with different oxygen doping amounts (in the figure, Ge = 0.9 means the Ge content in the material is 90%, the oxygen doping amount is 10%, and the same applies to the rest). It can be found that as the oxygen doping amount increases (i.e., from Ge = 0.9 to Ge = 0.1), the refractive index and extinction coefficient of the oxygen-doped germanium material decrease accordingly. Then, by tuning the refractive index value and extinction coefficient value of the oxygen-doped germanium material, various long-wave pass effects with different requirements can be obtained, and the specific implementation principle will be specifically introduced in the following content.

[0045] Referring to Figures 2 to 5 , it can be found that the oxygen-doped germanium thin film has a relatively high refractive index in the range of 300 to 1000 nm (compared with the refractive index value of about 1.5 of the silicon oxide material), and has certain variation characteristics in different wavelength regions. In the region of about 300 - 600 nm, the refractive index value of the oxygen-doped germanium thin film in this region basically increases with the increase of the wavelength; in the region from 600 nm to the long wave region, the refractive index of the oxygen-doped germanium thin film decreases basically monotonically with the increase of the wavelength, and in the region from the red light region to the near-infrared region, the trend of the refractive index of the oxygen-doped germanium thin film changing with the wavelength slows down, and the dispersion effect is weak; for the extinction coefficient, it can be found that in the region of 300 - 500 nm, the extinction coefficient of the oxygen-doped germanium thin film in this region is large, showing high absorption characteristics; in the region of 500 - 700 nm, the extinction coefficient of the oxygen-doped germanium thin film begins to decrease rapidly, and at this time it has weak absorption characteristics; in the region from the red light region to the near-infrared region, the extinction coefficient of the oxygen-doped germanium thin film continuously decreases and begins to approach 0 value, showing extremely weak absorption characteristics.

[0046] Based on the characteristics of the above oxygen-doped germanium thin film and silicon oxide thin film, the present invention thus provides a long-wave pass filter, and the specific principle of this filter is as follows.

[0047] The variation characteristics of the refractive index of the oxygen-doped germanium thin film material in the ultraviolet to infrared wavelength band and the characteristics of the extinction coefficient of the oxygen-doped germanium thin film material in the ultraviolet to infrared wavelength band can be used to help select the central wavelength of the filter film. The selection of the central wavelength can be based on actual requirements (such as the wavelength band of the light to be blocked).

[0048] In this embodiment, we selected the central wavelength to be 400 nm. The function of this filter is realized as follows: Based on the characteristics of the Bragg reflector, a high-reflection band is formed at the midpoint of the central wavelength of 400 nm. The bandwidth of this high-reflection band is determined by the refractive index difference between the high and low refractive indices at the central wavelength, that is, by the refractive index difference between the oxygen-doped germanium thin film and the silicon oxide thin film, which determines the bandwidth of the high-reflection band at this point. The larger the refractive index difference, the larger the bandwidth of the high-reflection band at this point. The high-reflection band here has a strong reflection ability for light. With the help of the low absorption characteristics of the oxygen-doped germanium thin film in this region, a high-blocking region can be formed to prevent photons in this wavelength band region from passing through; in the short-wave direction of this high-blocking region, only relying on the high absorption characteristics of the oxygen-doped germanium thin film material, a high-blocking region will also be formed in this region to effectively prevent photons in this wavelength band region from passing through; at the same time, in the long-wave band direction, since the absorption coefficient of the material is almost close to 0, a passband with a relatively high transmittance is easily formed. Coupled with the use of the long-wave pass film layer structure, the first-order oscillation of the transmittance in the passband region can be suppressed to a certain extent.

[0049] In other embodiments, according to the design requirements, other central wavelengths and oxygen-doped germanium thin films with different doping amounts can also be selected. According to the different selections of the central wavelength and the oxygen-doped germanium thin film with different doping amounts, long-wave pass filter films with different passband regions can be obtained.

[0050] To verify the feasibility of the specific principle of the long-wave pass filter, optical simulation calculations were carried out according to the selected central wavelength and materials above. In this embodiment, the TMM (Transfer Matrix Method) model was used to calculate the reflection spectrum, absorption spectrum, and transmittance spectrum values of the oxygen-doped germanium / silicon oxide long-wave pass filter film system on the silicon substrate. In this calculation, the film system structure of the filter is G / 0.5H(LH) m L0.5H / A structure, and the film layer materials are oxygen-doped germanium thin film with an oxygen doping amount of 10% and silicon oxide thin film, with a central wavelength of 400 nm. After multiple iterations, m was determined to be 20. The final output result is the reflection spectrum, absorption spectrum, and transmittance spectrum values of the long-wave pass filter with the film system structure of G / 0.5H(LH) 20 L0.5H / A, a central wavelength of 400 nm, and film layer materials of oxygen-doped germanium thin film with an oxygen doping amount of 10% and silicon oxide thin film, as shown Figure 6 in the figure. As Figure 6As shown, the reflection spectrum (R), transmission spectrum (T), and absorption spectrum curve (A) estimated by the TMM model correspond to the red, blue, and black curves in the figure, respectively. In the TMM calculation of this embodiment, it is assumed that the silicon substrate is infinitely thick, and only the propagation of light at the interface is calculated. Due to the high refractive index of the silicon substrate, regular oscillations appear in the calculated values of the transmission spectrum and reflection spectrum in the long-wave range.

[0051] The results of the further optical density values are as Figure 7 shown. Figure 7 It can be found from that in the wavelength band of about 200 to 600 nm, the optical density value basically tends to be saturated (about 5), having a good light blocking effect. In the direction of the long-wave band, the optical density value approaches 0, which is the long-wave passband region of the filter. And combined with Figure 6 it can be known that in the interval where its transmittance value is large, the optical density value coincides well with the TMM calculated value. From the Figure 7 results and the TMM calculation results, it shows that from about 600 nm to the short-wave direction, this long-wave pass filter film has an optical density value greater than 5, which can well achieve the blocking of short-wave band light waves, and has a good transmittance in the long-wave direction.

[0052] In this embodiment, the structure design of the long-wave pass filter film is mainly introduced with oxygen-doped germanium thin film and a central wavelength of 400 nm. The idea of the present invention is described with this embodiment, but its practical scope is not limited to the described single case. In other embodiments, other central wavelengths can be selected, and the structure of the long-wave pass filter film can be designed according to the above method.

[0053] Embodiment 2:

[0054] The content of this embodiment is basically the same as that of Embodiment 1, except that the selection of the high refractive index thin film material in the long-wave pass filter film system and the number of periods in the corresponding film system structure are different. In this embodiment, a critical case is selected, that is, an undoped oxygen germanium thin film is used, and the corresponding film system structure obtained is G / 0.5H(LH) 2 L0.5H / A. Among them, the thickness of the H layer is 24 nm, and the thickness of the L layer is 67 nm.

[0055] Figure 8 are the calculated values of the reflectivity (R), transmittance (T), and absorptivity (A) of this long-wave pass filter. As Figure 8 shown, the reflection spectrum (R), transmission spectrum (T), and absorption spectrum curve (A) estimated by the TMM model correspond to the green, red, and black curves in the figure, respectively. It can be seen from the transmission spectrum that the filter starts to open from about 650 nm, and the transmittance slowly increases at a lower slope to about 60%, also showing the typical characteristics of the long-wave pass filter film system.

[0056] Embodiment 3:

[0057] The long - wave pass filter film system of the present utility model can be used as an independent optical component, or can be integrated with other optoelectronic devices through semiconductor processes. For example, it can be integrated with a photomultiplier tube or a CMOS image sensor for fluorescence detection. In this embodiment, the long - wave pass filter film system of the present utility model is grown on a silicon - based photomultiplier tube wafer to form an integrated device. The specific method will be described in detail below.

[0058] Figure 9 It is a schematic structural diagram of an integrated device provided in Embodiment 2 of the present utility model. As Figure 9 shown, an integrated device including a long - wave pass filter film system is provided. The structure of the integrated device includes: a silicon substrate 1, a photomultiplier tube 11, a silicon oxide spacer layer 10, and a long - wave pass filter film system.

[0059] As Figure 9 shown, on the surface of the silicon substrate 1, there is arranged a photomultiplier tube array 11 formed by a plurality of photomultiplier tubes 11 (the structure composed of the silicon substrate 1 and the photomultiplier tube array arranged thereon can be denoted as a silicon - based photomultiplier tube wafer). On the photomultiplier tube array, a silicon oxide spacer layer 10 and a long - wave pass filter film system are sequentially arranged.

[0060] The silicon oxide spacer layer 10 can isolate the photomultiplier tube array from the long - wave pass filter film system. The thickness of the silicon oxide spacer layer 10 should be much larger than the peak wavelength of the photomultiplier tube photon detection efficiency (PDE). Particularly, in this embodiment, the thickness of the silicon oxide spacer layer 10 is set to 2 μm or greater than 2 μm. The silicon oxide spacer layer 10 here is used to ensure the normal realization of the function of the long - wave pass filter film system.

[0061] In this embodiment, the long - wave pass filter film system is the long - wave pass filter film system described in Embodiment 1 with a central wavelength of 400 nm and a film system structure of 0.5H(LH) 20 L0.5H. Specifically, on the silicon oxide spacer layer 10, there is provided a germanium oxide film 2 with an eighth - wavelength thickness; then followed by a periodic structure 3, which is a periodic alternating arrangement of silicon oxide films 31 / germanium oxide films 32 with a quarter - wavelength thickness, a total of 20 pairs, 40 layers, and then another silicon oxide film 31 is added; on the surface of the periodic structure 3, there is provided a germanium oxide film 4 with an eighth - wavelength thickness. That is, the total film layer structure of the long - wave pass filter film has 43 layers, and its total thickness is only about 3 μm. In other embodiments, the long - wave pass filter film system structure can be 0.5H(LH) m L0.5H, where m is greater than 2.

[0062] After the integrated device of the above long-pass filter film system and the silicon-based photomultiplier tube is fabricated, TSV vias (i.e., through-silicon vias) and wafer-level packaging can be performed on the back of the silicon-based photomultiplier tube to lead out electrodes from the back. On the long-pass filter thin film system on its front, it is adhered to a transparent glass substrate with a certain thickness using optical glue as a protective layer to protect the long-pass filter film system. Finally, using a laser dicing machine, the silicon-based photomultiplier tube that has completed wafer-level TSV packaging is cut into individual discrete devices (including multiple silicon-based photomultiplier tubes and the long-pass filter film system thereon).

[0063] By adding a long-pass filter film system on the surface of the photomultiplier tube, the light waves in the short-wave range can be effectively truncated, resulting in a decrease in the detection efficiency of the photomultiplier tube for short-wave photons, and only maintaining a relatively high detection efficiency for long-wave photons, which is suitable for fluorescence detection.

[0064] In this embodiment, the integration of the long-pass filter film system and the photomultiplier tube is taken as an example; in other embodiments, it can also be integrated with other types of fluorescence detection units with fluorescence detection functions such as CMOS image sensors or photodetectors.

[0065] Some common English nouns or letters used in the present utility model for the convenience of clear description are only for exemplary reference rather than restrictive interpretation or specific usage, and the protection scope of the present utility model should not be limited by their possible Chinese translations or specific letters.

[0066] It should also be noted that in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

Claims

1. A long wave pass filter, characterized in that: The film structure of the filter is: G / 0.5H(LH) m L0.5H / A, wherein G represents the substrate, H represents a high refractive index film with an optical thickness of one quarter of the central wavelength, L represents a low refractive index film with an optical thickness of one quarter of the central wavelength, m represents the number of periods, and A represents the air medium; the low refractive index film is a silicon oxide film; and the high refractive index film is an oxygen-doped germanium film.

2. A long-wave pass filter according to claim 1, characterized in that: The period number m is greater than 2.

3. A long-wave pass filter according to claim 2, characterized in that: The film structure of the filter is: G / 0.5H(LH) 20 L0.5H / A.

4. An integrated device, characterized in that: include: Silicon substrate, fluorescence detection unit, silicon oxide spacer layer and long-wave pass filter film system; A fluorescence detection unit is arranged on the silicon substrate, and the silicon oxide spacer layer and the long-wave pass filter film system are arranged in sequence on the surface of the fluorescence detection unit; The thickness of the silicon oxide spacer layer is greater than the peak wavelength of the photon detection efficiency of the fluorescence detection unit; The structure of the long-wave filter system is 0.5H (LH) m L0.5H, wherein H represents a high refractive index film having an optical thickness of one quarter of the central wavelength, L represents a low refractive index film having an optical thickness of one quarter of the central wavelength, and m represents the number of periods; the low refractive index film is a silicon oxide film; and the high refractive index film is an oxygen-doped germanium film.

5. An integrated device according to claim 4, characterized in that: There is at least one fluorescence detection unit. When there are multiple fluorescence detection units, the multiple fluorescence detection units are arranged on the silicon substrate in the form of an array.

6. An integrated device according to claim 4, characterized in that: A protective layer is arranged on the surface of the long-wave pass filter film.

7. An integrated device according to claim 5, characterized in that: The fluorescence detection unit is a photomultiplier tube, and a plurality of the photomultiplier tubes are arranged on the silicon substrate in the form of an array.

8. An integrated device according to claim 7, characterized in that: The thickness of the silicon oxide spacer layer is above 2 um.

9. An integrated device according to claim 4, characterized in that: The structure of the long-wave filter system is 0.5H (LH) 20 L0.5H.

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