Method for preparing Ge / Si SACM APD

Abstract

The invention discloses a novel method for preparing an ultrahigh-gain Ge / Si SACM APD. According to the method, after a Si epitaxial wafer and a Ge wafer are subjected to surface treatment, a-Si with the thickness of 3 nm is sputtered on a Ge / Si bonding interface by adopting a high-vacuum in-situ sputtering bonding technology to serve as a bonding intermediate layer, and then in-situ bonding is directly carried out under high vacuum; and through step-by-step long-time annealing, stripping of the Si-based Ge thin film is realized. Putting the stripped Si-based Ge film into a high-vacuum annealing furnace for high-temperature annealing to realize the release of non-uniform strain of the Ge film and the repair of point defects; preparing a P + contact layer by polishing and ion implantation; and finally, the absorption, charge and multiplication separation type high-performance Ge / Si SACM APD with a vertical structure is prepared through photoetching, etching, passivation and other processes. The responsivity of the Ge / Si APD device with the diameter of 30 [mu] m is 1.145 A / W and 2.57 A / W under the wavelength of 1310 nm and 1550 nm, the gains can reach 1.79 * 10 < 6 > and 1.69 * 10 < 5 > respectively, and the dark current is as low as 1.79 [mu] A.

Description

Technical Field

[0001] The present invention relates to a new method in the field of semiconductor device preparation, which can prepare ultra-high gain Ge / Si SACM APD. Specifically, a high vacuum in-situ sputtering bonding technology is used to in-situ sputter 3 nm a-Si as a bonding intermediate layer at the Ge / Si bonding interface to achieve Ge / Si lattice isolation, inhibit the generation of threading dislocations in the Ge film, prepare a high-quality Si-based Ge film with zero threading dislocation, no interface oxide layer, and zero bubbles, and prepare an absorption, charge and multiplication separation type high-performance Ge / Si SACM APD through photolithography, etching and coating technology. Background Art

[0002] Ge / Si near-infrared photodetectors are widely used in military reconnaissance, night vision imaging, and communications due to their advantages such as high carrier mobility and high absorption rate in the communication band. Since epitaxial technology can achieve large-scale single-crystal film growth, epitaxial technology plays a key role in the preparation of Si-based Ge thin films. For materials Ge and Si, due to the 4.2% lattice mismatch between Ge / Si, the traditional method of epitaxially growing Ge thin films on Si substrates often forms high-density threading dislocations (10 6 cm -2 ) and high roughness, which leads to problems such as large dark current, poor stability, reduced gain and noise in epitaxial Ge / Si APD. Therefore, it is necessary to reduce threading dislocations and surface roughness in Ge thin films to reduce device dark current and improve device performance. Summary of the invention

[0004] The purpose of the present invention is to propose a new preparation method for the problems of low gain and high dark current in Ge / Si SACM APD, and successfully solve the above problems. First, a Si-based Ge film with no interface oxide layer, high bonding strength and zero bubbles is prepared by high vacuum in-situ sputtering bonding technology, and then the Si-based Ge film is subjected to processes such as photolithography, etching and sputtering to prepare a Ge / Si SACM APD with a vertical structure and ultra-high gain. The Ge / Si SACM APD prepared by this method has a device with a diameter of 30 μm and a responsivity of 1.145 A / W and 2.57 A / W at wavelengths of 1310 nm and 1550 nm, respectively, and the gain can reach 1.79×10 6 and 1.69×10 5 , the dark current is as low as 1.79 μA; when the Ge / Si APD device with a diameter of 50 μm has a responsivity of 0.58 A / W and 1.5 A / W at 1310 nm and 1550 nm, the gain reaches 1.17×10 6 and 2×105 , dark current as low as 12.7 μA.

[0005] The present invention provides a method for preparing Ge / Si SACM APD, which includes the following technical features: First, after surface treatment of Si epitaxial wafer and Ge wafer, a-Si is sputtered as a bonding intermediate layer on the Ge / Si bonding interface by high vacuum in-situ sputtering bonding technology, and then in-situ bonding is directly performed under high vacuum; then the bonded Ge / Si is annealed for a long time in steps to realize the peeling of Si-based Ge film; Secondly, the peeled Si-based Ge film is placed in a high vacuum annealing furnace for high-temperature annealing to release the uneven strain of the Ge film and repair the point defects; then the repaired Si-based Ge film is polished and ion implanted to prepare the P+ contact layer; Finally, a Ge / Si SACM APD with vertical absorption, charge and multiplication separation structure was prepared through processes such as lithography, etching and passivation.

[0006] The surface treatment of Si epitaxial wafers and Ge wafers includes the following: First, ion implantation is performed: a plasma chemical vapor deposition system is used to deposit SiO2 on the surface of the Ge wafer as an ion implantation protective layer, and then H + Ion implantation; A single crystal Si epitaxial wafer is grown on a Si substrate, and then boron ions are implanted on the surface of the Si epitaxial wafer. Rapid thermal annealing is then used to activate the implanted boron ions to form a P-type lightly doped charge layer. After the ion implantation is completed, chemical cleaning is performed: HF:H2O solution is used to soak the SiO2 on the surface of the Ge wafer, and the SiO2 protective layer is corroded to obtain the processed Si epitaxial wafer and Ge wafer.

[0007] The process of using high vacuum in-situ sputtering bonding technology to sputter a-Si on Si epitaxial wafers and then perform in-situ bonding; and using long-term annealing in steps to achieve the peeling of Si-based Ge thin films includes: After the surface treatment, Si epitaxial wafers and Ge wafers are dried by a glue spreader and quickly placed into the cavity of a double-sided magnetron hot-pressing sputtering machine. -4 When 200 Å / s, Ar gas is filled into the sputtering chamber, and the pressure in the sputtering chamber is adjusted by changing the Ar gas flow rate to deposit an a-Si film on the Si epitaxial wafer. After the a-Si film is sputtered, the Si epitaxial wafer is directly bonded with the Ge wafer in the cavity of the double-sided magnetron hot-pressing sputtering machine; The Ge / Si bonding-completed sample was placed in a tube furnace and annealed in steps for a long time in a N2 atmosphere to achieve the peeling of the Si-based Ge film.

[0008] The process of releasing the uneven strain of Ge film and repairing point defects includes: The peeled Si-based Ge film is placed in a high vacuum annealing furnace for annealing in a high vacuum environment to achieve the release of uneven strain and the repair of point defects in the Ge film.

[0009] Polishing and ion implantation will be used to prepare P + The contact layer process includes: The surface of the Ge film is polished using a chemical mechanical polishing machine; The polished Ge film was placed in a quartz beaker, and an appropriate amount of alcohol was poured into it, and then placed in a water bath to remove the paraffin on the back of the Si substrate. After the alcohol water bath, the Si-based Ge film was ultrasonically treated with acetone, ethanol and deionized water in turn to remove the particles adsorbed on the surface of the Ge film. Boron ions are implanted on the surface of the cleaned Ge film, and then SiO2 film is deposited on the surface of the Ge film using PECVD. Finally, the sample is placed in a tubular annealing furnace and annealed in a N2 atmosphere to activate the implanted boron ions.

[0010] The process of preparing Ge / Si SACM APD with vertical absorption, charge and multiplication separation structure through photolithography, etching and passivation includes: Step 1: Degassing the Si-based Ge thin film sample implanted with boron ions, and after degassing, photolithography is performed to achieve hardening of the photoresist; after hardening, the sample is etched, and after etching, the sample is cleaned and the photoresist is removed; Step 2: After hardening, the sample Si-based Ge film is etched, and after etching, the photoresist is removed and then compound deposition and growth are performed on the sample Si-based Ge film. After compound growth is completed, the Si-based Ge film sample is hardened with photoresist again. After hardening, the Si-based Ge film sample is etched, and after etching, the photoresist is removed, and then the sample is dried and photolithography developed; Step 3: magnetron sputtering is used to sputter the front and back sides of the Si-based Ge thin film sample after photolithography development. After sputtering, the Ge / Si sample is immersed in an acetone solution and the adhesive is peeled off, and finally a Ge / Si SACM APD photodetector is prepared.

[0011] The process of step 1 includes: The Ge film after ion activation was immersed in HF:H2O solution to corrode the SiO2 protective layer; then the Ge film was ultrasonically cleaned with acetone, ethanol and deionized water in turn, rinsed with deionized water, and then dried with a glue spreader, and finally the sample was placed in an oven to remove water vapor; After removing the water vapor, the Si-based Ge thin film sample is spin-coated with a thickener and photoresist using a coater, and then the sample is placed on a heating table to pre-bake the photoresist. Next, a UV photolithography machine is used to perform the first version of the sample to define the upper surface. After the sample is photolithographically processed, it is developed using a developer, and finally the developed sample is placed in an oven to achieve a hard film of the photoresist.

[0012] The process of step 2 includes: The hardened sample was etched by dry and wet methods. First, the sample was placed in an ICP etcher for dry etching, with sulfur hexafluoride as the etching gas. Then, the sample was placed in an etching solution of H3PO4:H2O2=3:1 for wet etching. After the etching is completed, the sample is placed in an ICP etcher to etch Si, and the etching gas is sulfur hexafluoride to achieve device isolation; Removing the photoresist from the etched sample, the steps are: ultrasonically cleaning the sample with acetone, ethanol and deionized water in sequence, and rinsing with deionized water to remove the photoresist; The cleaned Ge / Si sample was dried by a spun coater, and then Al2O3 was deposited on the surface of the Ge film by an atomic layer deposition system. After the growth was completed, the sample was placed in the chamber of the atomic layer deposition system, and SiO2 and Si3N4 were deposited in sequence. After the growth, the sample is spin-coated with a thickener and a photoresist on the surface of the Si-based Ge film using a coating machine, and then the sample is placed on a heating table to pre-bake the photoresist, and then the sample is photoetched using a UV photolithography machine to define the electrode hole position, and then the sample is developed using a developer, and finally the developed sample is placed in an oven to harden the photoresist film; After the hardening step, the sample is etched with trifluoromethane and argon to remove Si3N4 and SiO2 on the surface of the Ge film, and then SiO2 and Al2O3 will remain on the surface of the sample. Then, BOE solution is used to etch away SiO2 and Al2O3 on the surface of the sample. The photoresist is removed from the etched sample, and the sample is ultrasonically cleaned with acetone, ethanol and deionized water in sequence, rinsed with deionized water, and then dried with a glue spreader, and finally placed in an oven for drying; After drying, the sample is first spin-coated with a thickener and photoresist on the surface of the Si-based Ge film sample using a coating machine, and then the sample is placed on a heating table to pre-bake the photoresist. Next, a photolithography machine is used to photolithography the sample to define the position of the electrode. Then the sample is placed on a heating table to post-bake the photoresist, and the photolithography machine is used to expose the sample, and then the sample is developed.

[0013] The process of step 3 includes: After the development is completed, Ti and Al are sputtered on the front and back sides of the Ge / Si sample by magnetron sputtering. Finally, the Ge / Si sample is immersed in an acetone solution and the adhesive is peeled off to finally prepare a Ge / Si SACM APD photodetector.

[0014] In summary, a Ge / Si SACM APD is characterized in that it is prepared according to the method of any one of claims 1 to 9; the Ge / Si SACM APD has the following characteristics: The Ge / Si SACM APD has the characteristics of vertical structure, separation of absorption, charge and multiplication. In addition, the Ge / Si SACM APD device with a diameter of 30 μm has a responsivity of 1.145 A / W and 2.57 A / W at 1310 nm and 1550 nm, respectively, and a gain of 1.79×10 6 and 1.69×10 5 , dark current as low as 1.79 μA.

[0015] When the diameter of the Ge / Si SACM APD is 50 μm, the responsivity of the Ge / Si SACM APD device at 1310 nm and 1550 nm is 0.58 A / W and 1.5 A / W, and the gain reaches 1.17×10 6 and 2×10 5 , dark current as low as 12.7 μA.

[0016] In order to implement the above method, the present invention adopts the following detailed technical steps: A novel method for preparing an ultra-high gain Ge / Si SACM APD comprises the following steps: 1) After the Si epitaxial wafer is ion-implanted with boron ions, rapid thermal annealing is performed at 1000 °C for 25 s; 2) The Si epitaxial wafer and Ge wafer were ultrasonically cleaned with acetone, ethanol and deionized water for 10 min respectively to remove particles and organic matter adsorbed on the substrate surface; 3) The cleaned Si epitaxial wafer was first boiled in a H2SO4 / H2O2 solution with a volume ratio of 4:1 for 10 min, rinsed with deionized water 15 times, then soaked in a HF / H2O solution with a volume ratio of 1:20 for 4 min, and rinsed with deionized water 15 times; 4) The cleaned Si epitaxial wafer was first boiled in a 1:1:4 volume ratio NH4OH / H2O2 / H2O solution for 10 min, rinsed 15 times with deionized water, then soaked in a 1:20 volume ratio HF / H2O solution for 4 min, and rinsed 15 times with deionized water; 5) The cleaned Si epitaxial wafer was first boiled in a HCL / H2O2 / H2O solution with a volume ratio of 1:1:4 for 10 min, rinsed with deionized water 15 times, then soaked in a HF / H2O solution with a volume ratio of 1:20 for 4 min, and rinsed with deionized water 15 times; 6) The Si epitaxial wafer cleaned in 5) and the Ge wafer cleaned in 2) are soaked in a solution with a volume ratio of HF:H2O=1:20 for 4 minutes, and then rinsed with deionized water for 10 to 15 times.

[0017] 7) After cleaning, use a glue spreader to spin dry the Si epitaxial wafer and Ge wafer, and then put them into a double-sided magnetron sputtering hot pressing machine. Wait until the background vacuum of the sputtering chamber is less than 1×10 -4 Pa, fill the sputtering chamber with Ar gas with a purity of 5N, and adjust the gas pressure in the sputtering chamber to keep it at 0.7 Pa.

[0018] 8) At room temperature, a 3 nm a-Si film was sputtered on the surface of the Si epitaxial wafer, and then the Si epitaxial wafer and the Ge wafer were quickly bonded together in the cavity. Then, in-situ hot pressing bonding was adopted, with an applied pressure of 12 MPa, a hot pressing temperature of 300 °C, a hot pressing time of 1 h, and a heating and cooling rate of 1 °C / min.

[0019] 9) The bonded Ge / Si bonded wafer is placed in an annealing furnace for low-temperature thermal annealing to achieve intelligent peeling of the Si-based Ge film, that is, to peel off a layer of Ge film from the Ge wafer and cover it on the Si-based amorphous Si; 10) The prepared Si-based Ge film was placed in a high vacuum annealing furnace at 500 °C in a vacuum environment, the annealing time was 1 h, and the heating and cooling rate was 0.5 °C / min.

[0020] 11) After the Ge film annealing is completed, the Ge film is polished for 5 min using a chemical mechanical polishing machine, with a rotation speed of 30 r / min and a swing arm of 15 r / min. The Ge film after polishing is placed in a quartz beaker, and an appropriate amount of alcohol is poured into it. The film is placed in a water bath at 80 °C for 20 min to remove the paraffin on the back of the Si substrate. The Ge film is then ultrasonically cleaned with acetone, ethanol and deionized water for 10 min in sequence to remove particles adsorbed on the surface of the Ge film.

[0021] 12) After cleaning, the Si-based Ge film is implanted with boron ions at a dose of 4×10 15 cm -2 The injection energy is 30 KeV. Then the injected Ge film sample is placed in a PECVD vacuum chamber to grow a 100nm SiO2 layer on the surface of the Ge film as an annealing protection layer.

[0022] 13) After the SiO2 growth is completed, the Ge film is placed in a tubular annealing furnace and annealed at 400 °C for 1 h in a N2 atmosphere.

[0023] 14) After annealing, the Ge film was immersed in a solution with a volume ratio of HF:H2O=1:20 for 15 min to etch off the SiO2 layer, and then ultrasonicated for 10 min using acetone, alcohol and water respectively, and finally rinsed with deionized water for 15 times. The Ge film was spun dry using a glue spreader and then dried in an oven at 135°C for 1 h to remove moisture.

[0024] 15) After the sample is dried, first use a coating machine to spin-coat the Ge film with a thickener and photoresist, then use a heating table at 96 °C to pre-bake the photoresist for 5 min, perform the first photolithography on the sample to define the upper table, then use a developer to develop for 55 s, and then use an oven at 120 °C to harden the film for 15 min to achieve the hardening of the photoresist. Then put the sample into an ICP etcher, and use dry and wet etching of the Ge film. The etching gas is sulfur hexafluoride (10 sccm) gas, the etching time is 180 s, and the electrode power (up / down) is 100 / 40 W. Then put the sample into a H3PO4:H2O2=3:1 etching solution for 1 min 30 s. Then the sample was put into the ICP etcher to etch Si, the etching gas was sulfur hexafluoride (30 sccm), the etching time was 29 s, and the electrode power (up / down) was 200 / 15 W to achieve device isolation. Finally, the sample was stripped of photoresist using acetone, alcohol and water.

[0025] 16) After cleaning the sample, spin dry the sample with a gel spreader and place it in ALD to deposit 10 nm Al2O3. Then, place the sample in a PECVD chamber to deposit 400 nm SiO2 and 200 nm Si3N4.

[0026] 17) After the sample growth is completed, the surface of the Ge / Si sample is firstly spin-coated with a coating machine to increase adhesion and photoresist, and then the photoresist is pre-baked for 5 min on a heating stage at 96 °C. Then, the sample is photoetched with a UV lithography machine to define the position of the electrode hole, and then baked in an oven at 120 °C for 15 min to achieve a hard film of the photoresist. Then, the sample is placed in an ICP etcher to etch Si3N4 and SiO2. The etching gas is trifluoromethane (100 sccm) and argon (20 sccm). The etching time is 125 s and 300 s. The electrode power (up / down) is 200 / 20 W. Then, 20 nm SiO2 and 10 nm Al2O3 will remain on the sample surface. The SiO2 and Al2O3 on the sample surface are etched with a BOE solution (3 ml HF: 6 g NH4F: 10 ml H2O) for 10 s. Finally, acetone, alcohol and water were used to remove the photoresist. After the sample was dried with a glue spreader, it was placed in an oven at 135 °C and baked for 1 h to remove water vapor.

[0027] 18) After the sample is baked, the photoresist is patterned using the third version of the photomask to define the position of the electrode, followed by post-baking for 4 minutes, flood exposure for 20 seconds, and then development with developer for 55 seconds. Then, 10 nm Ti / 300 nm Al is magnetron sputtered on the sample surface as an electrode. Finally, the sample is immersed in an acetone solution for 24 hours and the adhesive is stripped off, and finally a Ge / Si SACM APD photodetector is prepared. Figure 4 shown.

[0028] The Ge / Si SACM APD photodetector prepared by this method was tested for light and dark current using a monochromator. The responsivity of the device with a diameter of 30 μm at 1310 nm and 1550 nm was 1.145 A / W and 2.57 A / W, respectively, and the gain could reach 1.79×10 6 and 1.69×10 5 , the dark current is as low as 1.79 μA; when the Ge / Si APD device with a diameter of 50 μm has a responsivity of 0.58 A / W and 1.5 A / W at 1310 nm and 1550 nm, the gain reaches 1.17×10 6 and 2×10 5, dark current as low as 12.7 μA.

[0029] The advantages of the present invention are: The present invention innovatively proposes a new method for preparing ultra-high gain Ge / Si SACM APD. By sputtering bonding under high vacuum, Si-based Ge thin films with zero bubbles, no interface oxide layer and high bonding strength can be prepared. Ge / Si SACM APD is prepared by photolithography, etching and coating technology. The Ge / Si SACM APD prepared by this method has a responsivity of 1.145 A / W and 2.57 A / W at 1310 nm and 1550 nm wavelengths, respectively, and the gain can reach 1.79×10 6 and 1.69×10 5 , the dark current is as low as 1.79 μA; when the Ge / Si APD device with a diameter of 50 μm has a responsivity of 0.58 A / W and 1.5 A / W at 1310 nm and 1550 nm, the gain reaches 1.17×10 6 and 2×10 5 , dark current as low as 12.7 μA. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the Ge / Si bonding process in Example 1 of the present invention.

[0032] Figure 2 This is a physical picture of the Ge / Si bonding obtained in Example 1 of the present invention.

[0033] Figure 3 The double crystal XRD diffraction pattern of the Si-based Ge film tested after annealing at 350°C and 500°C in Example 1 of the present invention.

[0034] Figure 4 3D device structure and cross-sectional view of the Ge / Si SACM APD in Example 1 of the present invention.

[0035] Figure 5 This is a dark current IV curve of Ge / Si SACM APD obtained in Example 1 of the present invention.

[0036] Figure 6 The optical response, responsivity and gain of the Ge / Si SACM APD 30 μm table obtained in Example 1 of the present invention at wavelengths of 1310 nm and 1550 nm.

[0037] Figure 7The optical response, responsivity and gain of the Ge / Si SACM APD 50 μm table obtained in Example 1 of the present invention at wavelengths of 1310 nm and 1550 nm. DETAILED DESCRIPTION

[0039] In order to make the contents of the present invention easier to understand, the technical solutions of the present invention are further described below in conjunction with specific implementation methods.

[0040] The equipment used is a DM300 hot-press sputtering machine, with two DC targets placed in the growth chamber. The target material used is a 5N (99.999%) high-purity Si round target. The thickness of the epitaxial Si film on the Si substrate used is 1.65 μm, the crystal orientation is (111), the impurity type is N-type, and the resistivity is 0.72 Ω•cm. The single crystal Ge substrate material used has a crystal orientation of (100), single-sided polishing, and a resistivity of >30 Ω•cm.

[0041] The adhesion promoter is AZ AD PROMOTER, the main component of which is hexamethyldisilazane (HMDS). The photoresist model is AZ5214E, and the developer model is JAZX-238; 1) First, a 100 nm SiO2 protective layer was deposited on the surface of the Ge wafer using a plasma chemical vapor deposition system (PECVD), and then H + Ion implantation. The implantation dose is 5×10 16 cm -2 The implantation energy is 150 KeV, and the ion beam deviates from the sample normal by 7° to prevent channeling. The Si epitaxial wafer is implanted with boron ions at a dose of 2×10 12 The implantation energy is 15 KeV, and the ion beam deviates from the sample normal by 7° to avoid the channeling effect. After the boron ion implantation, rapid thermal annealing at 1000 °C for 25 s is used to activate the implanted boron ions and form a 100 nm charge layer; 2) The activated Si epitaxial wafer and Ge wafer were subjected to organic ultrasound for 10 min in acetone, alcohol and water respectively to remove the particles and organic matter adsorbed on the substrate surface; 3) The cleaned Si epitaxial wafer was first boiled in a H2SO4 / H2O2 solution with a volume ratio of 4:1 for 10 min, rinsed with deionized water 15 times, then soaked in a HF / H2O solution with a volume ratio of 1:20 for 4 min, and rinsed with deionized water 15 times; 4) The cleaned Si epitaxial wafer was first boiled in a 1:1:4 volume ratio NH4OH / H2O2 / H2O solution for 10 min, rinsed with deionized water 15 times, then soaked in a 1:20 volume ratio HF / H2O solution for 4 min, and rinsed with deionized water 15 times; 5) The cleaned Si epitaxial wafer was first boiled with a HCL / H2O2 / H2O solution with a volume ratio of 1:1:4 for 10 min and then rinsed with deionized water 15 times; 6) The cleaned Si epitaxial wafer and the cleaned Ge wafer were soaked in a solution with a volume ratio of HF:H2O=1:20 for 4 minutes, and then rinsed with deionized water 15 times; 7) Reference Figure 1 Schematic diagram of bonding process. After the cleaned Si epitaxial wafer and Ge wafer are dried by glue spreader, they are placed in double-sided magnetron sputtering hot pressing machine. When the background vacuum of the sputtering chamber is less than 1×10 -4 Pa, fill the sputtering chamber with 5N pure Ar gas, and control the pressure in the sputtering chamber to 0.7 Pa. At room temperature, sputter 3 nm a-Si film on the surface of Si epitaxial wafer, and then Si epitaxial wafer and Ge wafer are quickly bonded together in the cavity. Then in-situ hot pressing bonding is adopted, the applied pressure is 12 MPa, the hot pressing temperature is 300 ℃, the hot pressing holding time is 1 h, and the heating and cooling rate is 1 ℃ / min; 8) After bonding, the Ge / Si bonded wafer is placed in a tubular annealing furnace for low temperature thermal annealing. The bubble diagram of the Ge / Si sample after annealing is as follows: Figure 2 As shown, the full bonding effect can be achieved, and then the sample is annealed at 350 ° C for 10 h in a nitrogen environment to achieve the intelligent peeling of the Si-based Ge film, that is, to peel a layer of Ge film from the Ge sheet and cover it on the Si-based a-Si; 9) The prepared Si-based Ge film was annealed in a high vacuum annealing furnace at 500 °C for 1 h in a vacuum environment, with a heating and cooling rate of 0.5 °C / min; 10)Reference Figure 3 The double crystal XRD diffraction patterns of the samples were tested after annealing at 350 ℃ and 500 ℃. It can be seen from the figure that the half-height width of the sample decreased from 100 arc seconds to 84 arc seconds as the temperature increased. This is because the disordered internal structure can achieve lattice isolation, inhibit the nucleation of misfit dislocations, and the point defects in the Ge film are repaired under high temperature annealing, thereby improving the crystal quality of the Ge film.

[0042] 11) After annealing, the Ge film was polished using a chemical mechanical polisher with a polishing time of 5 min, a rotation speed of 30 r / min, and an arm swing of 15 r / min. The polished Ge film was placed in a quartz beaker, and an appropriate amount of alcohol was poured into the beaker. The beaker was placed in a water bath at 80 °C for 20 min to remove the paraffin on the back of the Si substrate.

[0043] 12) The cleaned Si-based Ge film is implanted with boron ions at a dose of 4×10 15 cm -2The injection energy is 30 KeV. Then the injected Ge film sample is placed in a PECVD vacuum chamber to grow a 100 nm SiO2 layer on the surface of the Ge film as an annealing protection layer; 13) After the growth of SiO2, the Ge film was placed in a tubular annealing chamber and annealed at 400 °C for 1 h in a N2 atmosphere; 14) After annealing, the Ge thin film sample was immersed in a solution with a volume ratio of HF:H2O=1:20 for 15 min to etch off the SiO2 layer, and then ultrasonicated with acetone, alcohol and water for 10 min respectively, and finally rinsed with deionized water for 15 times. The Ge thin film sample was dried with a glue spreader and placed in an oven at 135 °C for 1 h to remove moisture; 15) After drying, firstly, the surface of Ge / Si sample was spin-coated with adhesion promoter and photoresist by using a coating machine, and then pre-baked for 5 min. Then, the sample was photolithographyed by UV photolithography machine to define the pattern of the upper surface. After the sample was photolithography, it was developed with developer for 55 s, and then baked in an oven at 120 ℃ for 15 min to achieve a hard film of photoresist. Then, Ge thin film was etched by dry and wet methods. First, the sample was placed in an ICP etcher for dry etching. The etching gas was sulfur hexafluoride (10 sccm) gas, the etching time was 180 s, and the electrode power (up / down) was 100 / 40 W. Then, the sample was placed in a H3PO4:H2O2=3:1 etching solution for wet etching, and the etching time was 1 min 30 s; then the sample was placed in an ICP etcher to etch Si, the etching gas was sulfur hexafluoride (30 sccm), the electrode power (up / down) was 200 / 15 W, and the etching time was 29 s, in order to isolate each device; finally, the sample was removed from the photoresist using acetone, alcohol and water; 16) After cleaning, the sample was dried using a gelling machine and placed in ALD to deposit 10 nm Al2O3. The sample was then placed in PECVD to deposit 400 nm SiO2 and 200 nm Si3N4. 17) After the growth is completed, the sample is firstly spin-coated with a tackifier and photoresist using a coating machine, and then pre-baked for 5 minutes. Then, the sample is photoetched with the second photomask to define the position of the electrode hole. The sample is baked in an oven at 120 °C for 15 minutes to achieve a hard film of the photoresist. Then, the sample is placed in an ICP etcher to etch Si3N4 and SiO2 respectively. The etching gas is trifluoromethane (100 sccm) and argon (20 sccm). The etching time is 125 s and 300 s. The electrode power (up / down) is 200 / 20 W. Then, the remaining 20 nm SiO2 is etched with a BOE solution (3 ml HF: 6 g NH4F: 10 ml H2O) for 10 s. Then, the sample is sequentially removed from the photoresist using acetone, alcohol and water. Then, the sample is dried using a coating machine and placed in an oven at 135 °C for 1 hour to remove water vapor. 18) After baking, firstly, the surface of the Ge / Si sample was spin-coated with a thickener and photoresist using a coating machine, and then the photoresist was pre-baked for 4 min using a heating table at 96 °C, and the sample was photoetched with the third photomask to define the position of the electrode, and then post-baked for 4 min, and then the sample was flood-exposed for 20 s, developed with a developer for 55 s, and then magnetron sputtered 10 nm Ti / 300 nm Al as an electrode on the sample surface. Finally, the sample was immersed in an acetone solution for 24 h and the adhesive was stripped, and finally a Ge / Si SACM APD photodetector was prepared; 19) The prepared Ge / Si SACM APD photodetector was tested for light and dark current using a monochromator. The gain of the Ge / SiSACM APD device with a diameter of 30 μm at 1310 nm and 1550 nm can reach 1.79×10 6 and 1.69×10 5 , responsivities are 1.145 A / W and 2.57 A / W respectively, and the dark current is as low as 1.79 μA.

[0044] 20) Schematic diagram of Ge / Si sample bonding by high vacuum in-situ sputtering and Figure 1 As shown, the actual picture of the bubbles in the Ge / Si sample after bonding is as follows Figure 2 As shown in the figure, it can be seen that this method can achieve the effect of full bonding of Ge / Si samples. Figure 3 The XRD diffraction patterns of the double crystals of the tested Si-based Ge film after annealing at 350 ℃ and 500 ℃ are shown in Figure 2. The half-height width of the Si-based Ge film peeled off at 350 ℃ is 100 arc seconds, which is due to the H +The half-width of the Si-based Ge film after annealing at 500 °C is reduced to 84 arc seconds. This is because the point defects in the Ge film are repaired under high-temperature annealing, and the crystal quality of the Ge film is improved. Figure 4 This is the three-dimensional structure diagram of Ge / Si SACM APD. Figure 5 The IV curves of the tested Ge / SiSACM APD devices with a diameter of 30 μm and 50 μm are shown in Figure 6. From Figure 6, it can be concluded that the gain of the Ge / Si APD device with a diameter of 30 μm at 1310 nm and 1550 nm can reach 1.79×10 6 and 1.69×10 5 , the responsivity is 1.145 A / W and 2.57 A / W respectively, and the dark current is as low as 1.79 μA. From Figure 7, it can be concluded that when the diameter of the Ge / Si APD device is 50 μm, the responsivity is 0.58 A / W and 1.5 A / W at 1310 nm and 1550 nm, and the gain reaches 1.17×10 6 and 2×10 5 , dark current as low as 12.7 μA.

[0045] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for preparing a Ge / Si SACM APD, characterized in that: include: First, the Si epitaxial wafer and the Ge wafer are surface treated, and then a-Si is sputtered as a bonding intermediate layer on the Ge / Si bonding interface using high vacuum in-situ sputtering bonding technology, and then in-situ bonding is directly performed under high vacuum; then the bonded Ge / Si is annealed for a long time in steps to achieve the peeling of the Si-based Ge film; Secondly, the peeled Si-based Ge film is placed in a high vacuum annealing furnace for annealing to release the uneven strain of the Ge film and repair the point defects; then the repaired Si-based Ge film is polished and ion implanted to prepare P + contact layer; Finally, a Ge / SiSACM APD with vertical absorption, charge and multiplication separation structure was prepared through lithography, etching and passivation processes.

2. A method for preparing Ge / Si SACM APD according to claim 1, characterized in that: The contents of surface treatment of Si epitaxial wafers and Ge wafers include: First, ion implantation is performed: a plasma chemical vapor deposition system is used to deposit SiO2 on the surface of the Ge wafer as an ion implantation protective layer, and then H + Ion implantation; A single crystal Si epitaxial wafer is grown on a Si substrate, and then boron ions are implanted on the surface of the Si epitaxial wafer. Rapid thermal annealing is then used to activate the implanted boron ions to form a P-type lightly doped charge layer. After the ion implantation is completed, chemical cleaning is performed: HF:H2O solution is used to soak the SiO2 on the surface of the Ge wafer, and the SiO2 protective layer is corroded to obtain the processed Si epitaxial wafer and Ge wafer.

3. The method for preparing Ge / Si SACM APD according to claim 1, characterized in that: High vacuum in-situ sputtering bonding technology is used to sputter a-Si on Si epitaxial wafers and Ge wafers, and then perform in-situ bonding; The process of stripping the Si-based Ge film by long-term annealing in steps includes: After the surface treatment, Si epitaxial wafers and Ge wafers are dried by a glue spreader and quickly placed into the cavity of a double-sided magnetron hot-pressing sputtering machine. -4 When 200 Å / s, Ar gas is filled into the sputtering chamber, and the pressure in the sputtering chamber is adjusted by changing the Ar gas flow rate to deposit an a-Si film on the Si epitaxial wafer. After the a-Si film is sputtered, the Si epitaxial wafer is directly bonded with the Ge wafer in the cavity of the double-sided magnetron hot-pressing sputtering machine to obtain a bonded Ge / Si sample; The Ge / Si bonding-completed sample was placed in a tube furnace and annealed in steps for a long time in a N2 atmosphere to achieve the peeling of the Si-based Ge film.

4. The method for preparing Ge / Si SACM APD according to claim 1, characterized in that: The process of releasing the uneven strain of Ge film and repairing point defects includes: The peeled Si-based Ge film is placed in a high vacuum annealing furnace for annealing in a high vacuum environment to achieve the release of uneven strain and the repair of point defects in the Ge film.

5. The method for preparing Ge / Si SACM APD according to claim 1, characterized in that: P was prepared by polishing and ion implantation + The contact layer process includes: The surface of the Ge film is polished using a chemical mechanical polishing machine; The polished Ge film was placed in a quartz beaker, and an appropriate amount of alcohol was poured into it, and then placed in a water bath to remove the paraffin on the back of the Si substrate. After the alcohol water bath, the Si-based Ge film was ultrasonically treated with acetone, ethanol and deionized water in turn to remove the particles adsorbed on the surface of the Ge film. Boron ions are implanted on the surface of the cleaned Ge film, and then a SiO2 film is deposited on the surface of the Ge film using a plasma chemical vapor deposition system. Finally, the sample is placed in a tubular annealing furnace and annealed in a N2 atmosphere to activate the implanted boron ions.

6. The method for preparing Ge / Si SACM APD according to claim 1, characterized in that: The process of fabricating a Ge / Si SACM APD with vertical absorption, charge and multiplication separation structures by photolithography, etching and passivation processes includes: Step 1: Degassing the Si-based Ge thin film sample implanted with boron ions, and after degassing, photolithography is performed to achieve hardening of the photoresist; after hardening, the sample is etched, and after etching, the sample is cleaned and the photoresist is removed; Step 2: After hardening, the sample Si-based Ge film is etched, and after etching, the photoresist is removed and then compound deposition and growth are performed on the sample Si-based Ge film. After compound growth is completed, the Si-based Ge film sample is hardened with photoresist again. After hardening, the Si-based Ge film sample is etched, and after etching, the photoresist is removed, and then the sample is dried and photolithography developed; Step 3: magnetron sputtering is used to sputter the front and back sides of the Si-based Ge thin film sample after photolithography development. After sputtering, the Ge / Si sample is immersed in an acetone solution and the adhesive is peeled off, and finally a Ge / Si SACM APD photodetector is prepared.

7. A method for preparing Ge / Si SACM APD according to claim 6, characterized in that: The process for Step 1 includes: The Ge film after ion activation was immersed in HF:H2O solution to corrode the SiO2 protective layer; then the Ge film was ultrasonically cleaned with acetone, ethanol and deionized water in turn, rinsed with deionized water, and then dried with a glue spreader, and finally the sample was placed in an oven to remove water vapor; After removing the water vapor, the Si-based Ge thin film sample is spin-coated with a thickener and photoresist using a coater, and then the sample is placed on a heating table to pre-bake the photoresist. Next, a UV photolithography machine is used to perform the first version of the sample to define the upper surface. After the sample is photolithographically processed, it is developed using a developer, and finally the developed sample is placed in an oven to achieve a hard film of the photoresist.

8. The method for preparing Ge / Si SACM APD according to claim 6, characterized in that: The process for Step 2 includes: The hardened sample was etched by dry and wet methods. First, the sample was placed in an ICP etcher for dry etching, with sulfur hexafluoride as the etching gas. Then, the sample was placed in an etching solution of H3PO4:H2O2=3:1 for wet etching. After the etching is completed, the sample is placed in an ICP etcher to etch Si, and the etching gas is sulfur hexafluoride to achieve device isolation; Removing the photoresist from the etched sample, the steps are: ultrasonically cleaning the sample with acetone, ethanol and deionized water in sequence, and rinsing with deionized water to remove the photoresist; The cleaned Ge / Si sample was dried by a spun coater, and then Al2O3 was deposited on the surface of the Ge film by an atomic layer deposition system. After the growth was completed, the sample was placed in the chamber of a plasma enhanced chemical vapor deposition system, and SiO2 and Si3N4 were deposited in sequence. After the growth, the sample is spin-coated with a thickener and a photoresist on the surface of the Si-based Ge film using a coating machine, and then the sample is placed on a heating table to pre-bake the photoresist, and then the sample is photoetched using a UV photolithography machine to define the electrode hole position, and then the sample is developed using a developer, and finally the developed sample is placed in an oven to harden the photoresist film; After the hardening step, the sample is etched with trifluoromethane and argon to etch the Si3N4 and SiO2 on the surface of the Ge film, and then SiO2 and Al2O3 will remain on the surface of the sample, and then BOE solution is used to etch away the SiO2 and Al2O3 on the surface of the sample; The photoresist is removed from the etched sample, and the sample is ultrasonically cleaned with acetone, ethanol and deionized water in sequence, rinsed with deionized water, and then dried with a glue spreader, and finally placed in an oven for drying; After drying, the sample is first spin-coated with a thickener and photoresist on the surface of the Si-based Ge film sample using a coating machine, and then the sample is placed on a heating table to pre-bake the photoresist. Next, a photolithography machine is used to photolithography the sample to define the position of the electrode. Then the sample is placed on a heating table to post-bake the photoresist, and the photolithography machine is used to expose the sample, and then the sample is developed.

9. The method for preparing Ge / Si SACM APD according to claim 6, characterized in that: The process for step 3 includes: After the sample is developed, Ti and Al are sputtered on the front and back of the Ge / Si sample by magnetron sputtering. Finally, the Ge / Si sample is immersed in an acetone solution and the adhesive is peeled off to finally prepare a Ge / Si SACM APD photodetector.

10. A Ge / Si SACM APD, characterized in that: Prepared according to the method of any one of claims 1 to 9; the Ge / Si SACM APD has the following characteristics: Ge / Si SACM APD has absorption, charge and multiplication separation parameter characteristics of vertical structure; When the diameter of Ge / Si SACM APD is 30 μm, the responsivity of the Ge / Si SACM APD device at 1310 nm and 1550 nm is 1.145 A / W and 2.57 A / W, and the gain reaches 1.79×10 6 and 1.69×10 5 , dark current as low as 1.79μA; When the diameter of the Ge / Si SACM APD is 50 μm, the responsivity of the Ge / Si SACM APD device at 1310 nm and 1550 nm is 0.58 A / W and 1.5 A / W, and the gain reaches 1.17×10 6 and 2×10 5 , dark current as low as 12.7 μA.

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