Multiband infrared detector and preparation method thereof

Abstract

The invention relates to the technical field of semiconductor manufacturing, in particular to a multiband infrared detector and a preparation method thereof. The invention provides a collaborative innovation scheme of low stress stripping and multiband physical stacking of silicon-based heteroepitaxy Hg (1-x n) CdxnTe. Aiming at the problems of strong substrate dependence, out-of-control warping rate of a large-size silicon substrate, difficulty in multi-band expansion and the like in the prior art, higher functionality and compatibility of silicon substrate, Hg (1-x n) CdxnTe and CMOS processes are realized through silicon-based ZnTe sacrificial layer design, a perfect stripping and transferring scheme and a high-precision physical stacking framework, the yield is improved, and the preparation complexity of a multi-band detector is reduced. According to the invention, warping of a molecular beam epitaxy silicon substrate can be solved, the dark current density is effectively reduced, and a multiband infrared detection function can be more efficiently and freely realized.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing technology, and in particular to a multi-band infrared detector and a preparation method thereof. Background Art

[0002] The current infrared detector field faces technological bottlenecks, particularly silicon-based integration. Traditional molecular beam epitaxy (MBE) processes, when heterogeneously growing HgCdTe on silicon, suffer from lattice mismatch, resulting in film residual stress exceeding 1 GPa, wafer warpage exceeding 50 μm, and device array yields below 40%. Furthermore, achieving multispectral infrared detection faces limitations. Existing multi-band solutions rely on MBE superlattices and compositional gradients, which exponentially increase the complexity of epitaxy.

[0003] The existing technology is to grow HgCdTe thin films on CdZnTe homogeneous substrates with molecular beam epitaxy, use bromine-methanol solution to corrode the CdZnTe substrate, peel off the HgCdTe thin film, and directly use the HgCdTe thin film for detector preparation. The dark current density of the detector reaches 1×10 -4 A / cm 2 , and only supports single-band detection.

[0004] There is also an existing technology that after epitaxially growing a HgCdTe film on a CdZnTe substrate, the HgCdTe film is bonded to a silicon substrate through a SiO2 intermediary layer, and then the CdZnTe substrate is removed by mechanical grinding. Specifically, it includes: molecular beam epitaxy of a 10μm HgCdTe film on a CdZnTe substrate, high-temperature bonding of the HgCdTe film to the silicon substrate (350-400°C, 5-10MPa pressure) through a SiO2 intermediary layer, and then mechanical grinding to remove the CdZnTe substrate, retaining the HgCdTe film, and integrating the detector. The dark current density of this detector is >1×10 -4 A / cm 2 , process yield is less than 50%, silicon wafer warpage is greater than 20μm, and multi-band detection is not supported. There is also a risk of high temperature causing leakage in the passivation layer.

[0005] Regarding multi-band infrared detection, existing technologies involve the use of molecular beam epitaxy (MBE) to grow a graded MCT layer (with continuously varying x values) on a Si substrate, achieving multi-band absorption through band engineering. Specifically, this involves growing a graded HgCdTe superlattice with Δx = 0.01-0.05 on a 4-inch Si substrate through MBE, and achieving absorption in different bands by adjusting the epitaxy parameters. The dark current density of this detector is 5×10 -4 A / cm 2 , process yield <30%, silicon wafer warpage >50μm, and supports multi-band detection.

[0006] Therefore, the existing technical solutions have problems such as uncontrolled silicon-based warping after silicon-based heteroepitaxial HgCdTe, insufficient complexity and flexibility in multi-band implementation, heterogeneous integration interface defects and performance degradation, uncontrollable wet stripping process and film damage. Summary of the Invention

[0007] In view of this, the technical problem to be solved by the present invention is to provide a multi-band infrared detector and a preparation method thereof, which can solve the warping of molecular beam epitaxial silicon base, effectively reduce the dark current density, and realize the multi-band infrared detection function more efficiently and freely.

[0008] The present invention provides a method for preparing a multi-band infrared detector, comprising the following steps:

[0009] A) Using molecular beam epitaxy method, ZnTe sacrificial buffer layer, CdTe buffer layer, Hg (1-x1) Cd x1 Te layer and CdTe protective layer;

[0010] B) spin coating a polymethyl methacrylate solution on the upper surface of the CdTe protective layer to form a polymethyl methacrylate film;

[0011] C) selectively etching the ZnTe sacrificial buffer layer using the mixed solution to obtain an epitaxial composite layer separated from the first silicon substrate;

[0012] The mixed solution includes ammonia water and hydrogen peroxide;

[0013] D) taking another second silicon substrate and removing the epitaxial composite layer, using acetone to remove the polymethyl methacrylate film of the epitaxial composite layer to obtain a first epitaxial layer; the first epitaxial layer includes a CdTe buffer layer, a Hg (1-x1) Cd x1 Te layer and CdTe protective layer;

[0014] E) preparing a second epitaxial layer according to the method of steps A) to D); the second epitaxial layer comprises a CdTe buffer layer, a Hg (1-x2) Cd x2 Te layer and CdTe protective layer; wherein x1-x2=Δx≥0.05;

[0015] The second epitaxial layer is carried on a polydimethylsiloxane transfer film and is stacked with the first epitaxial layer with high precision through alignment and stamping;

[0016] F) removing the polydimethylsiloxane transfer film by heating, and repeating step E) to obtain a multi-band infrared detector.

[0017] Preferably, in step A), the process parameters for the molecular beam epitaxy of the ZnTe sacrificial buffer layer include: vacuum degree of the growth chamber <1×10 -9 Torr, epitaxial temperature was 270-300℃, and Zn beam flow rate was 4×10 -7 ~5×10 -7 Torr, Te beam flux is 4×10 -7 ~5×10 -7 Torr;

[0018] After the molecular beam epitaxy of the ZnTe sacrificial buffer layer, the method further comprises: annealing; the annealing temperature is 420-440° C., the time is 110-130 s, and the Te beam flow rate is maintained at 0.8×10 -6 ~1.2×10 -6 Torr;

[0019] The thickness of the ZnTe sacrificial buffer layer is 300-500 nm.

[0020] Preferably, in step A), the process parameters for molecular beam epitaxy of the CdTe buffer layer include: vacuum degree of the growth chamber <1×10 -9 Torr, epitaxial temperature was 260-280℃, and CdTe beam flow rate was 0.8×10 -6 ~1.2×10 -6 Torr, Te beam flux is 4×10 -7 ~5×10 -7 Torr;

[0021] After the molecular beam epitaxy of the CdTe buffer layer, the method further comprises: annealing; the annealing temperature is 470-490° C., the time is 110-130 s, and the Te beam flow rate is maintained at 0.8×10 -6 ~1.2×10 -6 Torr;

[0022] The thickness of the CdTe buffer layer is 3-4 μm.

[0023] Preferably, in step A), x1=0.15-0.70;

[0024] Molecular beam epitaxy Hg (1-x1) Cd x1 The process parameters of the Te layer include: vacuum degree of the growth chamber <1×10 -9 Torr, epitaxial temperature is 180~190℃, CdTe beam flow rate is 4×10 -7 ~9×10 -7 Torr, Te beam flux is 1×10 -6 ~3×10 -6 Torr, Hg beam flux is 6×10 -5 ~9×10 -5 Torr;

[0025] The Hg (1-x1) Cd x1 The thickness of the Te layer is 5 to 8 μm.

[0026] Preferably, in step A), the process parameters for the molecular beam epitaxy of the CdTe protective layer include: vacuum degree of the growth chamber <1×10 -9 Torr, epitaxial temperature was 260-280℃, and CdTe beam flow rate was 0.8×10 -6 ~1.2×10 -6 Torr, Te beam flux is 4×10 -7 ~5×10 -7 Torr;

[0027] The thickness of the CdTe protective layer is 500-800 nm.

[0028] Preferably, in step B), the thickness of the polymethyl methacrylate film is 2 to 4 μm.

[0029] Preferably, in step C), in the mixed solution, the mass ratio of the ammonia water to the hydrogen peroxide is 2-4:1-3;

[0030] The pH value of the mixed solution is 8 to 9;

[0031] The temperature of the selective corrosion is 20-25° C., and the time is 5-8 minutes.

[0032] Preferably, in step E), the thickness of the PDMS transfer film is 150 to 300 μm;

[0033] The punching process parameters include: punching movement step ≤ 0.05 μm, pressure 20-30 kPa, and time 2-3 min.

[0034] The error of the high-precision stacking is ≤0.05 μm.

[0035] Preferably, in step F), the heating temperature is 50-80° C. and the heating time is 5-10 min;

[0036] Repeating step E) includes:

[0037] Repeat step E) to stack Hg with high precision (1-xn) Cd xnThe epitaxial layer of the Te film is used to construct a multi-band infrared detector; and x(n-1)-xn=Δx≥0.05; Δx refers to the difference between xn in two adjacent epitaxial layers; n≥3.

[0038] The present invention also provides a multi-band infrared detector prepared by the preparation method described above.

[0039] The present invention provides a silicon-based heteroepitaxial Hg (1-xn) Cd xn A collaborative innovation solution for low-stress stripping of Te and multi-band physical stacking. Aiming at the problems of strong substrate dependence, uncontrolled curvature of large-scale silicon-based materials, and difficulty in multi-band expansion in existing technologies, the design of silicon-based ZnTe sacrificial layer, perfect stripping and transfer scheme, and high-precision physical stacking architecture are used to achieve the goal of silicon-based, Hg (1-xn) Cd xn Te and CMOS processes offer greater functionality and compatibility, with yields increasing to over 65%, reducing the complexity of multi-band detector fabrication. This invention addresses the warping of silicon substrates grown using molecular beam epitaxy (MBE), effectively reducing dark current density and enabling more efficient and flexible multi-band infrared detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A flow chart of the preparation process of the multi-band infrared detector provided by the present invention;

[0041] Figure 2 This is a schematic structural diagram of a 5-band detector prepared in Example 1 of the present invention;

[0042] Figure 3 This is a schematic structural diagram of the 7-band detector prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0043] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0044] The present invention provides a method for preparing a multi-band infrared detector, comprising the following steps:

[0045] A) Using molecular beam epitaxy method, ZnTe sacrificial buffer layer, CdTe buffer layer, Hg (1-x1) Cd x1 Te layer and CdTe protective layer;

[0046] B) spin coating a polymethyl methacrylate (PMMA) solution on the upper surface of the CdTe protective layer to form a polymethyl methacrylate (PMMA) film;

[0047] C) selectively etching the ZnTe sacrificial buffer layer using the mixed solution to obtain an epitaxial composite layer separated from the first silicon substrate;

[0048] The mixed solution includes ammonia water and hydrogen peroxide;

[0049] D) taking another second silicon substrate, fishing out the epitaxial composite layer, and removing the polymethyl methacrylate (PMMA) film of the epitaxial composite layer with acetone to obtain a first epitaxial layer; the first epitaxial layer includes a CdTe buffer layer, a Hg (1-x1) Cd x1 Te layer and CdTe protective layer;

[0050] E) preparing a second epitaxial layer according to the method of steps A) to D); the second epitaxial layer comprises a CdTe buffer layer, a Hg (1-x2) Cd x2 Te layer and CdTe protective layer; wherein x1-x2=Δx≥0.05;

[0051] The second epitaxial layer is carried on a polydimethylsiloxane (PDMS) transfer film and is stacked with the first epitaxial layer with high precision through alignment and stamping;

[0052] F) removing the polydimethylsiloxane (PDMS) transfer film by heating, and repeating step E) to obtain a multi-band infrared detector.

[0053] Figure 1 This is a flow chart of the preparation process of the multi-band infrared detector provided by the present invention.

[0054] Regarding step A):

[0055] The ZnTe sacrificial buffer layer, CdTe buffer layer, Hg (1-x1) Cd x1 Te layer and CdTe protective layer.

[0056] In some embodiments of the present invention, the thickness of the first silicon substrate is 595-605 μm, for example, 600 μm.

[0057] In some embodiments of the present invention, the process parameters for the molecular beam epitaxy of the ZnTe sacrificial buffer layer include: the vacuum degree of the growth chamber is less than 1×10 -9 Torr, epitaxial temperature was 270-300℃, and Zn beam flow rate was 4×10 -7 ~5×10-7 Torr, Te beam flux is 4×10 -7 ~5×10 -7 Torr. Specifically, the vacuum degree of the growth chamber is less than 1×10 -9 Torr, the epitaxial temperature was 280 °C, and the Zn beam flow rate was 4 × 10 -7 Torr, Te beam flux is 4×10 -7 Torr.

[0058] After the molecular beam epitaxy of the ZnTe sacrificial buffer layer, the method further comprises: annealing; the annealing temperature is 420-440° C., the time is 110-130 s, and the Te beam flow rate is maintained at 0.8×10 -6 ~1.2×10 -6 Specifically, the annealing temperature is 430°C, the time is 120s, and the Te beam flow rate is maintained at 1×10 -6 Torr.

[0059] In some embodiments of the present invention, the thickness of the ZnTe sacrificial buffer layer is 300-500 nm, such as 400 nm.

[0060] The process parameters of molecular beam epitaxy CdTe buffer layer include: vacuum degree of growth chamber <1×10 -9 Torr, epitaxial temperature is 260~280℃, CdTe beam flow rate is 0.8×10 -6 ~1.2×10 -6 Torr, Te beam flux is 4×10 -7 ~5×10 - 7 Torr. Specifically, the vacuum degree of the growth chamber is less than 1×10 -9 Torr, the epitaxial temperature was 270 °C, and the CdTe beam flux was 1 × 10 - 6 Torr, Te beam flux is 5×10 -7 Torr.

[0061] After the molecular beam epitaxy of the CdTe buffer layer, the method further comprises: annealing; the annealing temperature is 470-490° C., the time is 110-130 s, and the Te beam flow rate is maintained at 0.8×10 -6 ~1.2×10 -6 Specifically, the annealing temperature is 480°C, the time is 120s, and the Te beam flow rate is maintained at 1×10 -6 Torr.

[0062] In some embodiments of the present invention, the thickness of the CdTe buffer layer is 3-4 μm, for example, 3 μm.

[0063] In some embodiments of the present invention, Hg (1-x1) Cd x1 In Te, x1 = 0.15 to 0.70, for example, 0.65, 0.70.

[0064] Molecular beam epitaxy Hg (1-x1) Cd x1 The process parameters of the Te layer include: vacuum degree of the growth chamber <1×10 -9 Torr, epitaxial temperature is 180~190℃, CdTe beam flow rate is 4×10 -7 ~9×10 -7 Torr, Te beam flux is 1×10 -6 ~3×10 - 6 Torr, Hg beam flux is 6×10 -5 ~9×10 -5 Torr. Specifically, the vacuum degree of the growth chamber is less than 1×10 -9 Torr, the epitaxial temperature was 185°C, and the CdTe beam flux was 8.5×10 -7 Torr or 9×10 -7 Torr, Te beam flux is 2×10 -6 Torr, Hg beam flux is 6.5×10 -5 Torr.

[0065] The molecular beam epitaxy Hg (1-x1) Cd x1 After the Te layer, no annealing is performed.

[0066] In some embodiments of the present invention, the Hg (1-x1) Cd x1 The thickness of the Te layer is 5-8 μm, for example, 5 μm.

[0067] In some embodiments of the present invention, the process parameters of the molecular beam epitaxy CdTe protective layer include: the vacuum degree of the growth chamber is less than 1×10 -9 Torr, epitaxial temperature is 260~280℃, CdTe beam flow rate is 0.8×10 -6 ~1.2×10 -6 Torr, Te beam flux is 4×10 -7 ~5×10 -7 Torr. Specifically, the vacuum degree of the growth chamber is less than 1×10 -9 Torr, the epitaxial temperature was 270 °C, and the CdTe beam flux was 1 × 10 -6Torr, Te beam flux is 4×10 -7 Torr.

[0068] After the molecular beam epitaxy of the CdTe protective layer, no annealing is performed.

[0069] In some embodiments of the present invention, the thickness of the CdTe protective layer is 500-800 nm, such as 600 nm.

[0070] Regarding step B):

[0071] The polymethyl methacrylate solution is spin-coated on the upper surface of the CdTe protective layer to form a polymethyl methacrylate film.

[0072] In some embodiments of the present invention, the mass concentration of the polymethyl methacrylate solution is 4% to 5%, such as 5%. The solvent of the polymethyl methacrylate solution is polymethyl methacrylate and anisole, and the mass ratio is 0.8 to 1.2:17 to 21, such as 1:19.

[0073] After the spin coating, the method further includes: drying.

[0074] In some embodiments of the present invention, the thickness of the polymethyl methacrylate film is 2-4 μm, for example, 3 μm. The polymethyl methacrylate film is used to protect the epitaxial layer obtained in step A) from being peeled off.

[0075] Regarding step C):

[0076] selectively etching the ZnTe sacrificial buffer layer using a mixed solution to obtain an epitaxial composite layer separated from the first silicon substrate;

[0077] The mixed solution includes ammonia water and hydrogen peroxide.

[0078] In some embodiments of the present invention, the mass ratio of the aqueous ammonia to hydrogen peroxide in the mixed solution is 2-4:1-3, for example, 3:2. The pH value of the mixed solution is 8-9, for example, 9. The mass concentration of the aqueous ammonia is 10%-25%, for example, 25%.

[0079] In some embodiments of the present invention, selectively etching the ZnTe sacrificial buffer layer using a mixed solution includes:

[0080] The composite layer obtained in step B) is immersed in the mixed solution to selectively etch the ZnTe sacrificial buffer layer.

[0081] The selective corrosion is performed at a temperature of 20 to 25° C., such as 25° C., and for a time of 5 to 8 minutes, such as 6 minutes.

[0082] In the present invention, H2O2 oxidizes Zn into soluble [Zn(OH)4] 2- , and the weak alkaline environment maintained by ammonia promotes the formation of Cd(OH) passivation layer on CdTe while maintaining Hg (1-x1) Cd x1 The chemical inertness of Hg in Te. While rapidly corroding ZnTe, it is also very effective in corroding CdTe and Hg (1-x1) Cd x1 The influence of Te can be controlled at the sub-nanometer level. After the ZnTe sacrificial layer is etched away, the epitaxial layer protected by the PMMA film floats on the surface of the mixed solution.

[0083] In some embodiments of the present invention, after the selective etching, the process further includes: removing the silicon substrate with a clean piece and washing it in deionized water to terminate the reaction. The washing may be performed 5 to 8 times, for example 5 times.

[0084] Regarding step D):

[0085] Take another second silicon substrate and fish out the epitaxial composite layer, use acetone to remove the polymethyl methacrylate (PMMA) film of the epitaxial composite layer to obtain the first epitaxial layer; the first epitaxial layer includes a CdTe buffer layer, a Hg (1-x1) Cd x1 Te layer and CdTe protective layer.

[0086] In some embodiments of the present invention, removing the PMMA film of the epitaxial composite layer using acetone includes:

[0087] The epitaxial composite layer is immersed in the acetone to remove the PMMA film of the epitaxial composite layer.

[0088] The soaking temperature is 20-25° C., such as 25° C.; and the soaking time is 3-6 minutes, such as 5 minutes.

[0089] In some embodiments of the present invention, the thickness of the second silicon substrate is 595-605 μm, such as 600 μm.

[0090] Regarding step E):

[0091] The second epitaxial layer is prepared according to the method of steps A) to D); the second epitaxial layer comprises a CdTe buffer layer, a Hg (1-x2) Cd x2 Te layer and CdTe protective layer; wherein x1-x2=Δx≥0.05;

[0092] The second epitaxial layer is carried on a polydimethylsiloxane (PDMS) transfer film and is stacked with the first epitaxial layer with high precision through alignment and stamping.

[0093] Specifically, x2=0.45, 0.55.

[0094] The PDMS transfer film is a PDMS film. In some embodiments of the present invention, the thickness of the PDMS transfer film is 150-300 μm, such as 300 μm.

[0095] In some embodiments of the present invention, the stamping process parameters include: a stamping movement step of ≤0.05 μm, a pressure of 20-30 kPa, and a time of 2-3 minutes to ensure sufficient contact. Specifically, the stamping movement step is 0.05 μm, the pressure is 30 kPa, and the time is 3 minutes.

[0096] In some embodiments of the present invention, the error of the high-precision stacking is ≤0.05 μm.

[0097] Regarding step F):

[0098] The PDMS transfer film is removed by heating, and step E) is repeated to obtain a multi-band infrared detector.

[0099] In some embodiments of the present invention, the heating temperature is 50-80°C, such as 65°C, and the heating time is 5-10 minutes, such as 10 minutes. (1-x2) Cd x2 The adsorption force of the Te film enables the PDMS transfer film to be easily removed.

[0100] In some embodiments of the invention, repeating step E) comprises:

[0101] Repeat step E) to stack Hg with high precision (1-xn) Cd xn Te thin film epitaxial layers can be used to construct multi-band infrared detectors, such as 5- to 7-band detectors. Furthermore, x(n-1)-xn=Δx≥0.05, where Δx refers to the difference between xn in two adjacent epitaxial layers. n≥3. Specifically, n=5 or 7.

[0102] Specifically, xn=0.35, 0.25, 0.18; or xn=0.40, 0.30, 0.25, 0.20, 0.15.

[0103] In some embodiments of the present invention, a 5-band detector comprises:

[0104] Silicon substrate;

[0105] A first epitaxial layer is formed on the silicon substrate; the first epitaxial layer comprises a first CdTe buffer layer, a Hg 0.35 Cd0.65 Te layer and a first CdTe protective layer;

[0106] A second epitaxial layer is formed on the first epitaxial layer; the second epitaxial layer comprises a second CdTe buffer layer, a Hg 0.55 Cd 0.45 Te layer and a second CdTe protective layer;

[0107] A third epitaxial layer is formed on the second epitaxial layer; the third epitaxial layer comprises a third CdTe buffer layer, a Hg 0.65 Cd 0.35 Te layer and a third CdTe protective layer;

[0108] A fourth epitaxial layer is formed on the third epitaxial layer; the fourth epitaxial layer comprises a fourth CdTe buffer layer, a Hg 0.75 Cd 0.25 Te layer and a fourth CdTe protective layer;

[0109] A fifth epitaxial layer is formed on the fourth epitaxial layer; the fifth epitaxial layer comprises a fifth CdTe buffer layer, a Hg 0.82 Cd 0.18 Te layer and a fifth CdTe protective layer.

[0110] The CdTe buffer layers described above are all the same. The CdTe protective layers described above are all the same.

[0111] In some embodiments of the present invention, the 7-band detector comprises:

[0112] Silicon substrate;

[0113] A first epitaxial layer is formed on the silicon substrate; the first epitaxial layer comprises a first CdTe buffer layer, a Hg 0.30 Cd 0.70 Te layer and a first CdTe protective layer;

[0114] A second epitaxial layer is formed on the first epitaxial layer; the second epitaxial layer comprises a second CdTe buffer layer, a Hg 0.45 Cd 0.55 Te layer and a second CdTe protective layer;

[0115] A third epitaxial layer is formed on the second epitaxial layer; the third epitaxial layer comprises a third CdTe buffer layer, a Hg 0.60 Cd 0.40 Te layer and a third CdTe protective layer;

[0116] A fourth epitaxial layer is formed on the third epitaxial layer; the fourth epitaxial layer comprises a fourth CdTe buffer layer, a Hg 0.70 Cd 0.30 Te layer and a fourth CdTe protective layer;

[0117] A fifth epitaxial layer is formed on the fourth epitaxial layer; the fifth epitaxial layer comprises a fifth CdTe buffer layer, a Hg 0.75 Cd 0.25 Te layer and a fifth CdTe protective layer;

[0118] A sixth epitaxial layer is formed on the fifth epitaxial layer; the sixth epitaxial layer comprises a sixth CdTe buffer layer, a Hg 0.80 Cd 0.20 Te layer and a sixth CdTe protective layer;

[0119] A seventh epitaxial layer is formed on the sixth epitaxial layer; the seventh epitaxial layer comprises a seventh CdTe buffer layer, a Hg 0.85 Cd 0.15 Te layer and a seventh CdTe protective layer.

[0120] The CdTe buffer layers described above are all the same. The CdTe protective layers described above are all the same.

[0121] The present invention also provides a multi-band infrared detector prepared by the preparation method described above.

[0122] Beneficial effects

[0123] 1) The multi-band infrared detector prepared by the present invention has an extremely low silicon-based warpage rate, is more compatible with the complementary metal oxide semiconductor (CMOS) process, and can significantly improve the chip yield.

[0124] 2) The existing technology causes a large dark current due to high-temperature bonding, while the low-temperature self-assembly of the present invention will significantly reduce the dark current density.

[0125] 3) The high-precision physical stacking of the present invention can realize the multi-band infrared detection function more efficiently and freely, significantly reducing the complexity of multi-band detector preparation.

[0126] The multi-band infrared detector of the present invention can be applied to multi-spectral medical imaging, smart phone infrared sensing, missile guidance, etc., breaking through the silicon-based heteroepitaxial Hg (1-xn) Cd xn The high warping technology bottleneck of Te is overcome to achieve low-cost modular integration of multi-band detectors.

[0127] The present invention has no particular limitation on the sources of the raw materials used above, and they can be generally commercially available.

[0128] In order to further illustrate the present invention, a multi-band infrared detector and a preparation method thereof provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0129] Example 1

[0130] 1) On the first silicon substrate (thickness 600 μm), a ZnTe sacrificial buffer layer with a thickness of 400 nm was grown by molecular beam epitaxy. The corresponding process parameters included: vacuum degree of the growth chamber < 1×10 -9 Torr, the epitaxial temperature was 280 °C, and the Zn beam flow rate was 4 × 10 - 7 Torr, Te beam flux is 4×10 -7 Torr;

[0131] After the molecular beam epitaxy of the ZnTe sacrificial buffer layer, the method further includes: annealing; the annealing temperature is 430° C., the time is 120 s, and the Te beam flow rate is maintained at 1×10 -6 Torr;

[0132] The thickness of the ZnTe sacrificial buffer layer is 400 nm.

[0133] On the basis of epitaxial ZnTe sacrificial buffer layer, CdTe buffer layer, Hg 0.35 Cd 0.65 Te layer, CdTe protective layer;

[0134] The process parameters of molecular beam epitaxy CdTe buffer layer include: vacuum degree of growth chamber <1×10 -9 Torr, the epitaxial temperature was 270 °C, and the CdTe beam flux was 1 × 10 -6 Torr, Te beam flux is 5×10 -7 Torr;

[0135] After the molecular beam epitaxy of the CdTe buffer layer, the method further includes: annealing; the annealing temperature is 480° C., the time is 120 s, and the Te beam flow rate is maintained at 1×10 -6 Torr;

[0136] The thickness of the CdTe buffer layer is 3 μm;

[0137] Molecular beam epitaxy Hg 0.35 Cd 0.65 The process parameters of the Te layer include: vacuum degree of the growth chamber <1×10 -9 Torr, the epitaxial temperature was 185°C, and the CdTe beam flux was 8.5×10 -7 Torr, Te beam flux is 2×10-6 Torr, Hg beam flux is 6.5×10 -5 Torr, no annealing;

[0138] The Hg 0.35 Cd 0.65 The thickness of the Te layer is 5 μm;

[0139] The process parameters of molecular beam epitaxy CdTe protective layer include: vacuum degree of growth chamber <1×10 -9 Torr, the epitaxial temperature was 270 °C, and the CdTe beam flux was 1 × 10 -6 Torr, Te beam flux is 4×10 -7 Torr, no annealing;

[0140] The thickness of the CdTe protective layer is 600 nm.

[0141] 2) Spin-coating a 5% mass concentration PMMA solution (the solvent is polymethyl methacrylate and anisole, with a mass ratio of 1:19) on the upper surface of the CdTe protective layer, and forming a 3 μm thick PMMA film after drying.

[0142] 3) immersing the composite layer obtained in step B) in the mixed solution, selectively etching the ZnTe sacrificial buffer layer at 25° C. for 6 minutes, removing the composite layer with a clean silicon substrate, and rinsing it in deionized water five times to terminate the reaction, thereby obtaining an epitaxial composite layer separated from the first silicon substrate;

[0143] The mixed solution includes hydrogen peroxide and ammonia water with a mass concentration of 25%; the mass ratio of the ammonia water to the hydrogen peroxide is 3:2; and the pH value of the mixed solution is 9.

[0144] 4) Take another second silicon substrate (thickness 600 μm) and fish out the epitaxial composite layer, soak the epitaxial composite layer in 25° C. acetone for 5 minutes to remove the PMMA film of the epitaxial composite layer, and obtain a first epitaxial layer; the first epitaxial layer includes a CdTe buffer layer, a Hg 0.35 Cd 0.65 Te layer and CdTe protective layer.

[0145] 5) Prepare a second epitaxial layer according to the method of steps 1) to 4); the difference between the second epitaxial layer and the first epitaxial layer is that: the Hg 0.35 Cd 0.65 The Te layer is replaced by Hg with different composition values 0.55 Cd 0.45 Te layer; the second epitaxial layer comprises a CdTe buffer layer, a Hg 0.55 Cd 0.45Te layer and CdTe protective layer;

[0146] The second epitaxial layer is carried on a 300μm thick PDMS transfer film and is stacked with the first epitaxial layer with high precision through alignment and stamping (stamping parameters include: stamping movement step of 0.05μm, pressure of 30kPa, and time of 3min); the error of the high-precision stacking is ≤0.05μm.

[0147] 6) removing the PDMS transfer film by heating at 65° C. for 10 min;

[0148] Prepare the third epitaxial layer according to the method of steps 1) to 4); the difference between the third epitaxial layer and the first epitaxial layer is that: the Hg 0.35 Cd 0.65 The Te layer is replaced by Hg with different composition values 0.65 Cd 0.35 Te layer; the third epitaxial layer includes a CdTe buffer layer, a Hg 0.65 Cd 0.35 Te layer and CdTe protective layer;

[0149] The third epitaxial layer is carried on a PDMS transfer film with a thickness of 300 μm, and is stacked with the second epitaxial layer with high precision through alignment and stamping (the stamping parameters include: stamping movement step of 0.05 μm, pressure of 30 kPa, and time of 3 minutes); the error of the high-precision stacking is ≤0.05 μm.

[0150] 7) Prepare a fourth epitaxial layer according to the method of steps 1) to 4); the difference between the fourth epitaxial layer and the first epitaxial layer is that: the Hg 0.35 Cd 0.65 The Te layer is replaced by Hg with different composition values 0.75 Cd 0.25 Te layer; the fourth epitaxial layer includes a CdTe buffer layer, a Hg 0.75 Cd 0.25 Te layer and CdTe protective layer;

[0151] The fourth epitaxial layer is carried on a PDMS transfer film with a thickness of 300 μm, and is stacked with the third epitaxial layer with high precision through alignment and stamping (the stamping parameters include: stamping movement step of 0.05 μm, pressure of 30 kPa, and time of 3 minutes); the error of the high-precision stacking is ≤0.05 μm.

[0152] 8) removing the PDMS transfer film by heating at 65° C. for 10 min;

[0153] Prepare the fifth epitaxial layer according to the method of steps 1) to 4); the difference between the fifth epitaxial layer and the first epitaxial layer is that: the Hg 0.35 Cd 0.65 The Te layer is replaced by Hg with different composition values 0.82 Cd 0.18 Te layer; the fifth epitaxial layer includes a CdTe buffer layer, a Hg 0.82 Cd 0.18 Te layer and CdTe protective layer;

[0154] The fifth epitaxial layer is carried on a PDMS transfer film with a thickness of 300 μm, and is stacked with the fourth epitaxial layer with high precision through alignment and stamping (the stamping parameters include: stamping movement step of 0.05 μm, pressure of 30 kPa, and time of 3 minutes); the error of the high-precision stacking is ≤0.05 μm.

[0155] Assembled into a 5-band detector with a cutoff wavelength of 16.0 μm, such as Figure 2 shown. Figure 2 This is a schematic diagram of the structure of the 5-band detector prepared in Example 1 of the present invention. After testing, the dark current of the 5-band detector can be as low as 5×10 -9 A / cm 2 (Tested using a Keithley 4200 source meter.) The warpage of the stacked silicon substrate was 1.0 μm (tested using a BrukerVision 64 white light interferometer). The yield rate can be increased to 70%.

[0156] Example 2

[0157] 1) On the first silicon substrate (thickness 600 μm), a ZnTe sacrificial buffer layer with a thickness of 400 nm was grown by molecular beam epitaxy. The corresponding process parameters included: vacuum degree of the growth chamber < 1×10 -9 Torr, the epitaxial temperature was 280 °C, and the Zn beam flow rate was 4 × 10 - 7 Torr, Te beam flux is 4×10 -7 Torr;

[0158] After the molecular beam epitaxy of the ZnTe sacrificial buffer layer, the method further includes: annealing; the annealing temperature is 430° C., the time is 120 s, and the Te beam flow rate is maintained at 1×10 -6 Torr;

[0159] The thickness of the ZnTe sacrificial buffer layer is 400 nm.

[0160] On the basis of epitaxial ZnTe sacrificial buffer layer, CdTe buffer layer, Hg 0.30Cd 0.70 Te layer, CdTe protective layer;

[0161] The process parameters of molecular beam epitaxy CdTe buffer layer include: vacuum degree of growth chamber <1×10 -9 Torr, the epitaxial temperature was 270 °C, and the CdTe beam flux was 1 × 10 -6 Torr, Te beam flux is 5×10 -7 Torr;

[0162] After the molecular beam epitaxy of the CdTe buffer layer, the method further includes: annealing; the annealing temperature is 480° C., the time is 120 s, and the Te beam flow rate is maintained at 1×10 -6 Torr;

[0163] The thickness of the CdTe buffer layer is 3 μm;

[0164] Molecular beam epitaxy Hg 0.30 Cd 0.70 The process parameters of the Te layer include: vacuum degree of the growth chamber <1×10 -9 Torr, the epitaxial temperature was 185°C, and the CdTe beam flux was 9×10 -7 Torr, Te beam flux is 2×10 -6 Torr, Hg beam flux is 6.5×10 -5 Torr, no annealing;

[0165] The Hg 0.30 Cd 0.70 The thickness of the Te layer is 5 μm;

[0166] The process parameters of molecular beam epitaxy CdTe protective layer include: vacuum degree of growth chamber <1×10 -9 Torr, the epitaxial temperature was 270 °C, and the CdTe beam flux was 1 × 10 -6 Torr, Te beam flux is 4×10 -7 Torr, no annealing;

[0167] The thickness of the CdTe protective layer is 600 nm.

[0168] 2) Spin-coating a 5% mass concentration PMMA solution (the solvent is polymethyl methacrylate and anisole, with a mass ratio of 1:19) on the upper surface of the CdTe protective layer, and forming a 3 μm thick PMMA film after drying.

[0169] 3) immersing the composite layer obtained in step B) in the mixed solution, selectively etching the ZnTe sacrificial buffer layer at 25° C. for 6 minutes, removing the composite layer with a clean silicon substrate, and rinsing it in deionized water five times to terminate the reaction, thereby obtaining an epitaxial composite layer separated from the first silicon substrate;

[0170] The mixed solution includes hydrogen peroxide and ammonia water with a mass concentration of 25%; the mass ratio of the ammonia water to the hydrogen peroxide is 3:2; and the pH value of the mixed solution is 9.

[0171] 4) Take another second silicon substrate (thickness 600 μm) and fish out the epitaxial composite layer, soak the epitaxial composite layer in 25° C. acetone for 5 minutes to remove the PMMA film of the epitaxial composite layer, and obtain a first epitaxial layer; the first epitaxial layer includes a CdTe buffer layer, a Hg 0.30 Cd 0.70 Te layer and CdTe protective layer.

[0172] 5) Prepare a second epitaxial layer according to the method of steps 1) to 4); the difference between the second epitaxial layer and the first epitaxial layer is that: the Hg 0.30 Cd 0.70 The Te layer is replaced by Hg with different composition values 0.45 Cd 0.55 Te layer; the second epitaxial layer comprises a CdTe buffer layer, a Hg 0.45 Cd 0.55 Te layer and CdTe protective layer;

[0173] The second epitaxial layer is carried on a 300μm thick PDMS transfer film and is stacked with the first epitaxial layer with high precision through alignment and stamping (stamping parameters include: stamping movement step of 0.05μm, pressure of 30kPa, and time of 3min); the error of the high-precision stacking is ≤0.05μm.

[0174] 6) removing the PDMS transfer film by heating at 65° C. for 10 min;

[0175] Prepare the third epitaxial layer according to the method of steps 1) to 4); the difference between the third epitaxial layer and the first epitaxial layer is that: the Hg 0.30 Cd 0.70 The Te layer is replaced by Hg with different composition values 0.60 Cd 0.40 Te layer; the third epitaxial layer includes a CdTe buffer layer, a Hg 0.60 Cd 0.40 Te layer and CdTe protective layer;

[0176] The third epitaxial layer is carried on a PDMS transfer film with a thickness of 300 μm, and is stacked with the second epitaxial layer with high precision through alignment and stamping (the stamping parameters include: stamping movement step of 0.05 μm, pressure of 30 kPa, and time of 3 minutes); the error of the high-precision stacking is ≤0.05 μm.

[0177] 7) Prepare a fourth epitaxial layer according to the method of steps 1) to 4); the difference between the fourth epitaxial layer and the first epitaxial layer is that: the Hg 0.30 Cd 0.70 The Te layer is replaced by Hg with different composition values 0.70 Cd 0.30 Te layer; the fourth epitaxial layer includes a CdTe buffer layer, a Hg 0.70 Cd 0.30 Te layer and CdTe protective layer;

[0178] The fourth epitaxial layer is carried on a PDMS transfer film with a thickness of 300 μm, and is stacked with the third epitaxial layer with high precision through alignment and stamping (the stamping parameters include: stamping movement step of 0.05 μm, pressure of 30 kPa, and time of 3 minutes); the error of the high-precision stacking is ≤0.05 μm.

[0179] 8) removing the PDMS transfer film by heating at 65° C. for 10 min;

[0180] Prepare the fifth epitaxial layer according to the method of steps 1) to 4); the difference between the fifth epitaxial layer and the first epitaxial layer is that: the Hg 0.30 Cd 0.70 The Te layer is replaced by Hg with different composition values 0.75 Cd 0.25 Te layer; the fifth epitaxial layer includes a CdTe buffer layer, a Hg 0.75 Cd 0.25 Te layer and CdTe protective layer;

[0181] The fifth epitaxial layer is carried on a PDMS transfer film with a thickness of 300 μm, and is stacked with the fourth epitaxial layer with high precision through alignment and stamping (the stamping parameters include: stamping movement step of 0.05 μm, pressure of 30 kPa, and time of 3 minutes); the error of the high-precision stacking is ≤0.05 μm.

[0182] 9) removing the PDMS transfer film by heating at 65° C. for 10 min;

[0183] Prepare the sixth epitaxial layer according to the method of steps 1) to 4); the difference between the sixth epitaxial layer and the first epitaxial layer is that: the Hg0.30 Cd 0.70 The Te layer is replaced by Hg with different composition values 0.80 Cd 0.20 Te layer; the sixth epitaxial layer includes a CdTe buffer layer, a Hg 0.80 Cd 0.20 Te layer and CdTe protective layer;

[0184] The sixth epitaxial layer is carried on a PDMS transfer film with a thickness of 300 μm, and is stacked with the fifth epitaxial layer with high precision through alignment and stamping (the stamping parameters include: stamping movement step of 0.05 μm, pressure of 30 kPa, and time of 3 minutes); the error of the high-precision stacking is ≤0.05 μm.

[0185] 10) removing the PDMS transfer film by heating at 65° C. for 10 minutes;

[0186] Prepare the seventh epitaxial layer according to the method of steps 1) to 4); the difference between the seventh epitaxial layer and the first epitaxial layer is that: the Hg 0.30 Cd 0.70 The Te layer is replaced by Hg with different composition values 0.85 Cd 0.15 Te layer; the seventh epitaxial layer comprises a CdTe buffer layer, a Hg 0.85 Cd 0.15 Te layer and CdTe protective layer;

[0187] The seventh epitaxial layer is carried on a PDMS transfer film with a thickness of 300 μm, and is stacked with the sixth epitaxial layer with high precision through alignment and stamping (the stamping parameters include: stamping movement step of 0.05 μm, pressure of 30 kPa, and time of 3 minutes); the error of the high-precision stacking is ≤0.05 μm.

[0188] Assembled into a 7-band detector with a cutoff wavelength of 18.0 μm, such as Figure 3 shown. Figure 3 This is a schematic diagram of the structure of the 7-band detector prepared in Example 2 of the present invention. After testing, the dark current of the 7-band detector can be as low as 1×10 -9 A / cm 2 (Tested using a Keithley 4200 source meter.) The warpage of the stacked silicon substrate was 1.2 μm (tested using a BrukerVision 64 white light interferometer). The yield rate can be increased to 65%.

[0189] The above embodiments are intended only to facilitate understanding of the methods and core concepts of the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein, but is intended to be construed in the widest manner consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a multi-band infrared detector, comprising the following steps: A) Using molecular beam epitaxy method, ZnTe sacrificial buffer layer, CdTe buffer layer, Hg (1-x1) Cd x1 Te layer and CdTe protective layer; B) spin coating a polymethyl methacrylate solution on the upper surface of the CdTe protective layer to form a polymethyl methacrylate film; C) selectively etching the ZnTe sacrificial buffer layer using the mixed solution to obtain an epitaxial composite layer separated from the first silicon substrate; The mixed solution includes ammonia water and hydrogen peroxide; D) taking another second silicon substrate and removing the epitaxial composite layer, using acetone to remove the polymethyl methacrylate film of the epitaxial composite layer to obtain a first epitaxial layer; the first epitaxial layer includes a CdTe buffer layer, a Hg (1-x1) Cd x1 Te layer and CdTe protective layer; E) preparing a second epitaxial layer according to the method of steps A) to D); the second epitaxial layer comprises a CdTe buffer layer, a Hg (1-x2) Cd x2 Te layer and CdTe protective layer; wherein x1-x2=Δx≥0.05; The second epitaxial layer is carried on a polydimethylsiloxane transfer film and is stacked with the first epitaxial layer with high precision through alignment and stamping; F) removing the polydimethylsiloxane transfer film by heating, and repeating step E) to obtain a multi-band infrared detector.

2. The preparation method according to claim 1, characterized in that In step A), the process parameters for the molecular beam epitaxy of the ZnTe sacrificial buffer layer include: vacuum degree of the growth chamber <1×10 -9 Torr, epitaxial temperature was 270-300℃, and Zn beam flow rate was 4×10 -7 ~5×10 -7 Torr, Te beam flux is 4×10 -7 ~5×10 -7 Torr; After the molecular beam epitaxy of the ZnTe sacrificial buffer layer, the method further comprises: annealing; the annealing temperature is 420-440° C., the time is 110-130 s, and the Te beam flow rate is maintained at 0.8×10 -6 ~1.2×10 -6 Torr; The thickness of the ZnTe sacrificial buffer layer is 300-500 nm.

3. The preparation method according to claim 1, characterized in that In step A), the process parameters for the molecular beam epitaxy of the CdTe buffer layer include: vacuum degree of the growth chamber <1×10 -9 Torr, epitaxial temperature is 260~280℃, CdTe beam flow rate is 0.8×10 -6 ~1.2×10 -6 Torr, Te beam flux is 4×10 -7 ~5×10 -7 Torr; After the molecular beam epitaxy of the CdTe buffer layer, the method further comprises: annealing; the annealing temperature is 470-490° C., the time is 110-130 s, and the Te beam flow rate is maintained at 0.8×10 -6 ~1.2×10 -6 Torr; The thickness of the CdTe buffer layer is 3-4 μm.

4. The preparation method according to claim 1, characterized in that In step A), x1=0.15-0.70; Molecular beam epitaxy Hg (1-x1) Cd x1 The process parameters of the Te layer include: vacuum degree of the growth chamber <1×10 -9 Torr, epitaxial temperature is 180~190℃, CdTe beam flow rate is 4×10 -7 ~9×10 -7 Torr, Te beam flux is 1×10 -6 ~3×10 -6 Torr, Hg beam flux is 6×10 -5 ~9×10 -5 Torr; The Hg (1-x1) Cd x1 The thickness of the Te layer is 5 to 8 μm.

5. The preparation method according to claim 1, characterized in that In step A), the process parameters for the molecular beam epitaxy of the CdTe protective layer include: vacuum degree of the growth chamber <1×10 -9 Torr, epitaxial temperature was 260-280℃, and CdTe beam flow rate was 0.8×10 -6 ~1.2×10 -6 Torr, Te beam flux is 4×10 -7 ~5×10 -7 Torr; The thickness of the CdTe protective layer is 500-800 nm.

6. The preparation method according to claim 1, characterized in that In step B), the thickness of the polymethyl methacrylate film is 2 to 4 μm.

7. The preparation method according to claim 1, characterized in that In step C), in the mixed solution, the mass ratio of the ammonia water to the hydrogen peroxide is 2-4:1-3; The pH value of the mixed solution is 8 to 9; The temperature of the selective corrosion is 20-25° C., and the time is 5-8 minutes.

8. The preparation method according to claim 1, characterized in that In step E), the thickness of the PDMS transfer film is 150 to 300 μm; The stamping process parameters include: stamping movement step ≤ 0.05 μm, pressure 20-30 kPa, time 2-3 min; The error of the high-precision stacking is ≤0.05 μm.

9. The preparation method according to claim 1, characterized in that In step F), the heating temperature is 50-80°C and the heating time is 5-10 minutes; Repeating step E) includes: Repeat step E) to stack Hg with high precision (1-xn) Cd xn The epitaxial layer of the Te film is used to construct a multi-band infrared detector; and x(n-1)-xn=Δx≥0.05; n≥3.

10. A multi-band infrared detector prepared by the preparation method according to any one of claims 1 to 9.

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