Search

CN-122002916-A - High-performance surface incidence silicon-based germanium detector structure and preparation method thereof

CN122002916ACN 122002916 ACN122002916 ACN 122002916ACN-122002916-A

Abstract

The invention relates to the technical field of semiconductor photoelectric devices and discloses a high-performance surface incidence silicon-based germanium detector structure and a preparation method thereof, wherein the structure comprises an SOI substrate, a silicon-containing substrate, an oxygen-buried layer and an inner ring doped region formed by etching top silicon from bottom to top in sequence; A local suspended silicon oxide template layer is arranged above the inner ring doped region, a germanium transverse epitaxial region is arranged between the oxygen buried layer and the template layer, the germanium transverse epitaxial region comprises an intrinsic germanium absorption layer and an outer ring doped region, a transverse PIN structure is formed by the germanium transverse epitaxial region and the inner ring doped region together, and an electrode penetrates through the template layer to realize electric connection of the corresponding region. During preparation, a suspension template and seed crystals are formed through selective etching back, and germanium is further transversely extended in the cavity to prepare the electrode. The invention decouples the light absorption and the carrier transmission direction, improves the response and bandwidth of the device, utilizes the boundary of the insulating layer to physically capture the interface mismatch dislocation so as to reduce dark current, is compatible with a standard CMOS platform, and is beneficial to large-scale low-cost integration.

Inventors

  • XUE CHUNLAI
  • ZHOU HUIRONG
  • CONG HUI
  • XU CHI

Assignees

  • 中国科学院半导体研究所

Dates

Publication Date
20260508
Application Date
20260410

Claims (10)

  1. 1. The high-performance surface incidence silicon-based germanium detector structure is characterized by comprising an SOI substrate (100), wherein the SOI substrate (100) sequentially comprises a silicon substrate (110), an oxygen burying layer (120) and an inner ring doping region (131) from bottom to top, and the inner ring doping region (131) is formed by partially etching top silicon of the SOI substrate (100); The silicon oxide template layer (200) is arranged above the inner ring doped region (131), and a part of the silicon oxide template layer (200) which is not supported by the inner ring doped region (131) is suspended above the oxygen burying layer (120) to form a semi-suspension state; The germanium transverse epitaxial region (300) is positioned between the oxygen-buried layer (120) and the silicon oxide template layer (200) in a semi-suspension state, and is transversely connected with the inner ring doped region (131), wherein the germanium transverse epitaxial region (300) comprises an intrinsic germanium absorption layer and an outer ring doped region (310) and forms a PIN structure together with the inner ring doped region (131); And an electrode (400) penetrating through the silicon oxide template layer (200) of the corresponding region and respectively forming electrical connection with the top surface of the inner ring doped region (131) and the top surface of the outer ring doped region (310).
  2. 2. The high performance surface incidence silicon-based germanium detector structure according to claim 1, wherein the thickness of the inner ring doped region (131) is 220 nm-2 μm; The inner ring doped region (131) is made of doped monocrystalline silicon.
  3. 3. The high performance surface incidence silicon-based germanium detector structure of claim 1, wherein the thickness of the silicon oxide template layer (200) is 200 nm-1 μm.
  4. 4. The high performance surface incidence silicon-based germanium detector structure of claim 1, wherein the lateral total width of the germanium lateral epitaxial region (300) is 600nm to 1.5 μm.
  5. 5. A method for manufacturing a high performance surface incidence silicon-based germanium detector structure, applied to the high performance surface incidence silicon-based germanium detector structure as claimed in any one of claims 1 to 4, comprising the steps of: Firstly, preparing an SOI substrate (100) composed of a silicon substrate (110), an oxygen buried layer (120) and top silicon, wherein the top silicon is doped to be in a doped state; next, depositing silicon oxide on the top silicon to obtain a silicon oxide template layer (200); Then, etching a mesa structure of the stack of the top silicon and the silicon oxide template layer (200); Then, selectively etching back the top silicon layer to obtain an inner ring doped region (131), and enabling an unsupported part of the silicon oxide template layer (200) to form a semi-suspension state; Then, using the inner ring doped region (131) as seed crystal, laterally extending germanium between the buried oxide layer (120) and the silicon oxide template layer (200) to obtain a germanium lateral epitaxial region (300), and forming an outer ring doped region (310) to obtain a complete PIN structure; etching the silicon oxide template layer (200) corresponding to the upper part of the outer ring doped region (310) and the upper part of the inner ring doped region (131) to form electrode holes; Finally, depositing metal in the electrode hole, and forming electrical connection with the inner ring doped region (131) and the outer ring doped region (310) respectively to obtain an electrode (400), thereby obtaining the high-performance surface incidence silicon-based germanium detector structure.
  6. 6. The method of claim 5, wherein in the step of depositing silicon oxide to obtain a silicon oxide template layer (200), a layer of the silicon oxide template layer (200) is deposited on the top silicon layer by a plasma chemical vapor deposition, low pressure chemical deposition, or atmospheric pressure chemical deposition process.
  7. 7. The method of claim 5, wherein in the step of selectively etching back the top silicon layer, the etching solution is a tetramethylammonium hydroxide solution, a potassium hydroxide solution, or an ethylenediamine-catechol solution; when the tetramethylammonium hydroxide solution is selected, the mass fraction of the tetramethylammonium hydroxide solution is 25%, and the temperature of the corrosion environment is 70-90 ℃.
  8. 8. The method of claim 5, wherein in the step of laterally extending germanium to obtain a germanium lateral epitaxial region (300), ultra-high vacuum chemical vapor deposition, low pressure chemical vapor deposition, or metal organic chemical vapor deposition is used to laterally extend germanium.
  9. 9. The method of fabricating a high performance surface incidence silicon-based germanium detector structure according to claim 5, wherein the step of forming the outer ring doped region (310) is performed by any one of: introducing a doping source to carry out in-situ doping before the end of the transverse epitaxial germanium; or doping is realized through an ion implantation process after the germanium lateral epitaxy is completed.
  10. 10. The method of fabricating a high performance surface-incident silicon-based germanium detector structure according to claim 5, wherein metal is deposited inside the electrode hole and electrically connected to the inner ring doped region (131) and the outer ring doped region (310), respectively, and the electrode (400) is deposited by an electron beam evaporation process, a magnetron sputtering process or a thermal evaporation process in the step of fabricating the electrode (400); the electrode (400) is made of Ni and Al combination, ti and Au combination, cr and Au combination or simple substance Al.

Description

High-performance surface incidence silicon-based germanium detector structure and preparation method thereof Technical Field The invention relates to the technical field of semiconductor photoelectric devices, in particular to a high-performance surface incidence silicon-based germanium detector structure and a preparation method thereof. Background In a silicon optoelectronic integrated system, a surface incidence type silicon-based germanium detector is a core device for realizing photoelectric signal conversion. Conventional surface-incidence silicon-based germanium detectors typically employ a vertical PIN structure, i.e., a bottom doped layer, an intrinsic absorption layer, and a top doped layer are sequentially disposed from bottom to top along the material epitaxial growth direction. In this conventional structure, the absorption direction of photons and the transport direction of carriers are parallel to each other. In order for the device to sufficiently absorb incident light of a specific wavelength to obtain higher photoelectric responsivity, it is necessary to increase the physical thickness of the intrinsic germanium layer. However, the increase of the thickness of the intrinsic layer lengthens the transit distance of the photo-generated carriers under the action of an electric field, so that the transit time of the carriers becomes longer, and the high-frequency operation bandwidth of the detector is reduced. Thus, conventional vertical structures have inherent contradictions between device responsivity and bandwidth. Meanwhile, the conventional surface incidence detector requires a surface doping region on top of the germanium absorbing layer and a metal electrode for external electrical connection. The physical presence of these top structures directly obscures a portion of the incident beam. In addition, the free carrier absorption effect and lattice scattering phenomenon caused by the high-concentration doped region of the top layer can cause extra loss of light energy, and further limit the improvement of the overall responsivity of the device. At the material preparation level, stress relief at the silicon-germanium interface can lead to high density threading dislocations inside the germanium epitaxial layer when the heteroepitaxial growth of germanium is performed directly on the silicon substrate due to the lattice constant mismatch of about 4% between the silicon material and the germanium material. These lattice defects that extend through the active region act as non-radiative recombination centers when the device is in operation, forming leakage channels within the material, causing a significant increase in dark current in the device, severely degrading the signal-to-noise level of the detector. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a high-performance surface incidence silicon-based germanium detector structure and a preparation method thereof, which solve the problems that the prior silicon-based germanium detector has lattice mismatch between silicon and germanium, high-density threading dislocation is easy to generate in a germanium epitaxial layer, and the lattice defects can serve as non-radiative recombination centers to cause the increase of dark current of a device, so that the signal-to-noise ratio and the overall photoelectric performance of the detector are limited. The invention also provides a high-performance surface incidence silicon-based germanium detector structure which can solve the problem that the bandwidth and the responsivity of the traditional surface incidence silicon-based germanium detector are mutually restricted. In order to solve the problems, the invention provides the following technical scheme: In a first aspect, the present invention provides a high performance surface incident silicon-based germanium detector structure, which adopts the following technical scheme: A high-performance surface incidence silicon-based germanium detector structure comprises an SOI substrate, an oxygen burying layer and an inner ring doping region, wherein the SOI substrate sequentially comprises a silicon substrate, an oxygen burying layer and the inner ring doping region from bottom to top, the inner ring doping region is formed by partial etching of top silicon of the SOI substrate, a silicon oxide template layer is arranged above the inner ring doping region, a part of the silicon oxide template layer, which is not supported by the inner ring doping region, is suspended above the oxygen burying layer to form a semi-suspension state, a germanium transverse epitaxial region is arranged between the oxygen burying layer and the silicon oxide template layer in the semi-suspension state and is transversely connected with the inner ring doping region, the germanium transverse epitaxial region comprises an intrinsic germanium absorption layer and an outer ring doping region, a PIN structure is formed together with the inne