Low-temperature epitaxial preparation method of single crystal film

Abstract

The invention discloses a low-temperature epitaxy method of a single crystal film and the single crystal film, germanium silicon is used as a buffer layer, and a doped silicon single crystal film is prepared in an epitaxy mode at the low temperature not higher than 550 DEG C. According to the invention, the germanium-silicon buffer layer is introduced, so that the crystal quality and doping distribution of doped epitaxial silicon can be remarkably improved, and the uniform highly-doped single crystal thin film which is almost defect-free can be prepared under a low-temperature epitaxial process; the method does not need to adopt a traditional deposition and etching selective growth mode under a high-temperature condition, and is simple in process and relatively low in cost.

Description

Technical Field

[0001] The invention relates to the field of semiconductor technology, and in particular to a low-temperature epitaxial preparation process. Background Art

[0002] With the development of CMOS technology, epitaxial growth of doped silicon thin films has become increasingly important. It can be widely used in the source / drain region of devices, epitaxial functional layers, and other fields. The key point of the above applications is that a relatively low temperature growth process is required to avoid diffusion between adjacent regions, so that the device is not damaged during the manufacturing process.

[0003] At present, the epitaxial growth of doped silicon thin films is usually carried out by reduced pressure chemical vapor deposition (RPCVD or LPCVD), and a doped epitaxial silicon layer is generated on the silicon surface using raw material gases such as silane, dichlorodihydrosilane, germane, diborane, and phosphine. It can also be combined with a selective deposition process, and gases such as HCl are added as an etchant during the reaction process, and deposition and etching are carried out simultaneously to achieve selective epitaxial growth of silicon. However, in order to obtain a suitable growth rate and film growth quality, epitaxial growth of single-crystal doped silicon thin films requires a higher reaction temperature (above 700C). Since silane does not contain Cl atoms and has low activation energy, although silane can be used to form a thin film at a relatively low temperature (slightly below 700C), the reaction rate of silane is difficult to control, the film has many defects and is generally a polycrystalline structure. In addition, doping atoms such as boron and phosphorus will diffuse into the non-doped layer due to the concentration gradient between adjacent layers, greatly affecting the performance of the device.

[0004] The above and other prior arts in the field of semiconductor technology show that it is particularly urgent to develop a technology for growing high-quality uniformly doped single-crystalline silicon at low temperature. Summary of the invention

[0005] Based on the above-described problem, the present invention proposes a low-temperature epitaxial preparation method for a single crystal thin film.

[0006] On the one hand, the present invention provides a low-temperature epitaxial preparation method of a single crystal film, comprising: forming a germanium silicon buffer layer on a substrate; and growing a doped epitaxial silicon single crystal film on the buffer layer using a low-temperature epitaxial process.

[0007] Optionally, the low temperature does not exceed 550° C., and the pressure in the epitaxial chamber is 0.1-80 Torr.

[0008] Optionally, the substrate comprises one of Si, Ge and III-V materials, preferably a silicon substrate.

[0009] Optionally, the substrate is subjected to a germanium ion implantation process to form the germanium silicon buffer layer.

[0010] Optionally, the ion implantation process further includes an annealing activation process.

[0011] Optionally, the buffer layer has a thickness of 1 nm to 10 μm.

[0012] Optionally, the single crystal film is p-type doped silicon or n-type doped silicon, and the dopant includes at least one of carbon, germanium, phosphorus, arsenic or boron, preferably boron.

[0013] Optionally, the specific steps of the epitaxial process include: introducing HCl and H gases in sequence under constant pressure and temperature conditions. 2 Surface treatment, then H 2 Silane, disilane, or trisilane is introduced as a carrier gas, and diborane is introduced at the same time to deposit the single crystal film.

[0014] Optionally, the diborane flow rate is greater than the silane flow rate.

[0015] In a second aspect, the present invention provides a single crystal thin film, during the formation process of which the above-mentioned low-temperature epitaxial preparation method is adopted.

[0016] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: (1) On the one hand, epitaxially preparing doped epitaxial silicon single crystal thin films at a low temperature not higher than 550° C. can avoid diffusion between other adjacent regions, so that other functional layers are not damaged during the manufacturing process.

[0017] (2) On the other hand, the introduction of a germanium-silicon buffer layer can significantly improve the crystal quality of doped epitaxial silicon, making it possible to prepare almost defect-free, uniform, highly doped single-crystalline films under a low-temperature preparation process. The germanium-silicon buffer layer can improve the adsorption characteristics of the reaction precursor source gas on the substrate surface, making the epitaxial layer growth rate controllable. At the same time, the germanium-silicon buffer layer can also inhibit the diffusion of doped atoms in the epitaxial layer, forming a single-crystalline film with a uniform doping concentration distribution.

[0018] (3) In addition, the germanium silicon buffer layer is formed by ion implantation, and the hydrogen atmosphere in the subsequent epitaxial reaction is used to repair the lattice damage caused by the ion implantation of germanium. The preparation method is convenient and the material quality is good.

[0019] (4) The above-mentioned low-temperature preparation method does not need to adopt the traditional deposition and etching selective growth mode under high-temperature conditions, and achieves high-quality highly doped epitaxial silicon single crystal thin films. The process is simple and the cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings of the present invention constitute a part of this specification and are used to further understand the present invention. The drawings illustrate embodiments of the present invention and together with the description are used to explain the principle of the present invention.

[0021] Figure 1 This is a schematic structural diagram of a boron-doped epitaxial silicon single crystal film prepared by low-temperature epitaxy according to the present invention.

[0022] Figure 2 This is a transmission electron microscope image of a boron-doped epitaxial silicon single crystal film prepared in a specific embodiment.

[0023] Figure 3 The figure is a transmission electron microscope selected area electron diffraction (SAED) pattern of a boron-doped epitaxial silicon single crystal film prepared in a specific embodiment.

[0024] Figure 4 This is a SIMS distribution diagram of boron doping in a boron-doped epitaxial silicon single crystal film prepared in a specific embodiment. DETAILED DESCRIPTION

[0025] The following detailed descriptions are all illustrative and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0026] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention.

[0027] A method for preparing a single crystal thin film according to an embodiment of the present invention, as follows Figure 1 , the method comprises the following steps: S1: forming a germanium silicon buffer layer on a substrate; S2: Growing an epitaxial doped silicon single crystal film on the buffer layer using a low-temperature epitaxial process.

[0028] More specifically, in step S1, the substrate may be made of conventional substrate materials in the art, including one of Si, Ge and III-V materials, preferably a silicon substrate.

[0029] In step S1, the germanium silicon buffer layer can be prepared by conventional preparation methods in the art, such as vapor deposition, ion implantation, etc. When the substrate of the present invention is silicon, it is preferred to use an ion implantation method with a relatively low temperature and a simple preparation process to implant germanium atoms into the silicon substrate to form a silicon germanium buffer layer, and the thickness of the buffer layer is 10nm~10μm, preferably 30~50nm. Annealing can also be selected after ion implantation for activation.

[0030] In step S2, the epitaxial temperature does not exceed 550°C, and optionally, such as 100°C, 150°C, 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, and the epitaxial chamber pressure is 0.1-80 Torr, and optionally, such as 10 Torr, 20 Torr, 30 Torr, 40 Torr. Under constant pressure and temperature conditions, HCl gas and H 2 Surface treatment, then H 2 The single crystal film is obtained by introducing a silicon source gas and a doping source gas into the carrier gas, and depositing the single crystal film. The single crystal film is p-type doped silicon or n-type doped silicon, and the dopant includes at least one of carbon, germanium, phosphorus, arsenic or boron, preferably boron, wherein the boron doping concentration can reach 1×10 20 ~1×10 21 cm -1 .

[0031] In a specific embodiment, (001) single crystal silicon is used as the substrate, and germanium ions are first implanted and annealed to form a 44nm germanium silicon buffer layer. Then, at 525℃, 10Torr constant pressure and temperature conditions, HCl and H2 are introduced successively. 2 Surface treatment, then H 2 Silane, disilane, or trisilane is introduced as a carrier gas, and diborane is introduced at the same time, wherein the flow rate of diborane is greater than the flow rate of the silane, disilane, or trisilane, and a boron-doped epitaxial silicon single crystal film is deposited, and its growth rate can reach 8Å / S. The hydrogen atmosphere during epitaxial deposition can also repair the lattice damage of the germanium ion implantation layer, Figure 2 This is a transmission electron microscope image, in which the atomic-level lattice arrangement of the germanium silicon layer can be observed. Figure 2 The interface between the boron-doped epitaxial silicon film and the germanium silicon buffer layer is clear, and no diffusion occurs, indicating that the germanium silicon buffer layer plays a good role in isolation and diffusion prevention. Figure 3 This is the transmission electron microscope selected area electron diffraction (SAED) image of the boron-doped epitaxial silicon film area, and the epitaxial layer shows a high-quality single crystal film. Figure 4 This is the SIMS distribution diagram of boron doped epitaxial silicon single crystal film, where boron is evenly distributed in the depth direction and its doping concentration reaches 1×10 20 cm -1 .

[0032] The basic concepts have been described above. Obviously, for those skilled in the art, the above detailed disclosure is only for example and does not constitute a limitation of the present invention. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements and corrections to the present invention. Such modifications, improvements and corrections are suggested in the present invention, so such modifications, improvements and corrections still belong to the spirit and scope of the exemplary embodiments of the present invention.

[0033] It should be understood that the embodiments described in the present invention are only used to illustrate the principles of the embodiments of the present invention. Other variations may also fall within the scope of the present invention. Therefore, as examples and not limitations, alternative configurations of the embodiments of the present invention may be considered consistent with the teachings of the present invention. Accordingly, the embodiments of the present invention are not limited to the embodiments explicitly introduced and described in the present invention.

Claims

1. A method for preparing a single crystal thin film, characterized in that: include: forming a silicon germanium buffer layer on the substrate; A doped epitaxial silicon single crystal film is grown on the buffer layer using a low-temperature epitaxial process.

2. The method for preparing a single crystal thin film according to claim 1, characterized in that ,, the low temperature does not exceed 550°C, and the pressure in the epitaxial chamber is 0.1~80Torr.

3. The method for preparing a single crystal thin film according to claim 1, characterized in that: The substrate includes one of Si, Ge and III-V materials.

4. The method for preparing a single crystal thin film according to claim 3, characterized in that: The substrate is silicon.

5. The method for preparing a single crystal thin film according to claim 4, characterized in that: The substrate is subjected to a germanium ion implantation process to form the germanium silicon buffer layer.

6. The method for preparing a single crystal thin film according to claim 5, characterized in that: The ion implantation process also includes an annealing activation process.

7. The method for preparing a single crystal thin film according to claim 1, characterized in that: The buffer layer has a thickness of 10 nm to 10 μm.

8. The method for preparing a single crystal thin film according to claim 1, characterized in that: The single crystal thin film is p-type doped silicon or n-type doped silicon.

9. The method for preparing a single crystal thin film according to claim 8, characterized in that: The dopant includes at least one of carbon, germanium, phosphorus, arsenic, or boron.

10. The method for preparing a single crystal thin film according to claim 9, characterized in that: The single crystal thin film is boron-doped epitaxial silicon.

11. The method for preparing a single crystal thin film according to claim 10, characterized in that: The low-temperature epitaxial process steps specifically include: under constant pressure and temperature conditions, introducing HCl and H2 gases in turn for surface treatment, then introducing silane, disilane, or trisilane using H2 as a carrier gas, and simultaneously introducing diborane to deposit the single crystal film.

12. The method for preparing a single crystal thin film according to claim 11, characterized in that: The diborane flow rate is greater than the silane flow rate.

13. A single crystal thin film made by the preparation method according to any one of claims 1 to 12.

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