Epitaxial deposition device for large-size silicon wafer

Abstract

An epitaxial deposition device of a large-size silicon wafer comprises a graphite base and a nozzle arranged in the middle of the graphite base, multiple layers of heat insulation rings are arranged on the graphite base and located on the periphery of the nozzle at intervals, and the heat conductivity of the heat insulation rings is different. According to the utility model, the influence of thermal radiation of the graphite base on the nozzle can be effectively isolated, thereby reducing the generation of sediments and improving the surface quality of an epitaxial silicon wafer.

Description

Technical Field

[0001] This utility model relates to the field of deposition technology for large-size silicon wafers, specifically to an epitaxial deposition apparatus for large-size silicon wafers. Background Technology

[0002] In semiconductor manufacturing, epitaxial growth processes, which deposit high-quality thin film layers on silicon wafers, are crucial to the electrical performance of devices. This process is typically carried out at high temperatures (>1000°C), where reactive gases (such as SiHCl3 / H2) are introduced into the reaction chamber through a quartz nozzle, and chemical vapor deposition (CVD) occurs on the silicon wafer on a heated graphite substrate to form the epitaxial layer.

[0003] However, the high-temperature environment presents a key problem: the heat from the graphite substrate is transferred to the nozzle through thermal radiation, causing the nozzle and its exit area to heat up. When the reactive gas flows through the high-temperature nozzle, it may decompose or deposit prematurely, forming solid residues (such as polycrystalline silicon or silicon carbide particles) at the nozzle orifice. These particles may enter the reaction zone with the gas flow, adhere to the silicon wafer surface, cause surface defects, and reduce the silicon wafer yield.

[0004] Traditional solutions typically focus on optimizing gas flow rates or nozzle materials (such as pure quartz), but with limited effectiveness. Nozzle deposition problems are particularly pronounced in higher-temperature processes (>1500°C) such as silicon carbide epitaxy. Utility Model Content

[0005] The present invention aims to provide an epitaxial deposition apparatus for large-size silicon wafers, which can effectively isolate the influence of thermal radiation from the graphite substrate on the nozzle, thereby reducing deposit formation and improving the surface quality of the epitaxial silicon wafer.

[0006] To solve the above technical problems, the technical solution adopted by this utility model is as follows: an epitaxial deposition device for large-size silicon wafers, including a graphite base and a nozzle disposed in the middle of the graphite base, wherein multiple layers of heat insulation rings are provided on the graphite base at intervals around the outer periphery of the nozzle, and the thermal conductivity of each layer of heat insulation rings is different.

[0007] Preferably, the thermal conductivity of each layer of insulation ring decreases sequentially from the outside to the inside.

[0008] Preferably, it includes three layers of heat insulation rings, with the outer heat insulation ring made of silicon carbide, the middle heat insulation ring made of graphite, and the inner heat insulation ring made of foamed quartz.

[0009] Preferably, the thermal conductivity of each layer of the insulation ring is distributed according to the rule that the outer layer is high, the middle layer is low, and the inner layer is between the outer and middle layers.

[0010] Preferably, it includes three layers of heat insulation rings: the outer heat insulation ring is made of silicon carbide, the middle heat insulation ring is made of foamed quartz, and the inner heat insulation ring is made of graphite.

[0011] Preferably, a metal reflective layer is provided on the inner side of the heat insulation ring.

[0012] Preferably, the metal reflective layer is made of aluminum foil or molybdenum foil.

[0013] Preferably, the heat insulation ring includes a cylindrical ring body and an outwardly extending portion located at the upper end of the ring body.

[0014] Beneficial effects

[0015] This invention achieves the following technical advantages through the synergistic design of multi-layer heterogeneous thermal conductivity insulation rings:

[0016] 1. High-efficiency thermal radiation blocking: The gradient combination of materials with different thermal conductivity (such as silicon carbide-graphite-foamed quartz) forms a stepped thermal resistance, which significantly reduces the heat transfer from the base to the nozzle. The nozzle temperature can be greatly reduced, thereby reducing the deposits caused by the premature decomposition of the reactive gas.

[0017] 2. Particulate contamination control: The metal reflective layer (aluminum / molybdenum foil) further reflects residual radiation, reducing the particle generation rate and significantly reducing the defect density on the silicon wafer surface.

[0018] 3. Structural compatibility: The extension at the top of the heat insulation ring increases the heat shielding area, adapting to nozzles of different sizes, without requiring any changes to the existing graphite base structure. Attached Figure Description

[0019] Figure 1 This is a longitudinal sectional view of Embodiment 1 of the present invention.

[0020] Figure 2 This is a longitudinal cross-sectional view of the heat insulation ring portion of Embodiment 3 of this utility model.

[0021] Figure 3 A longitudinal cross-sectional view of the heat insulation ring portion of Embodiment 4 of this utility model;

[0022] The markings in the diagram are: 1. Nozzle, 2. Graphite base, 3. Plate groove, 4. Heat insulation ring, 401. Ring body, 402. Extension, 5. Metal reflective layer. Detailed Implementation

[0023] The technical solution of this utility model is described below through four embodiments:

[0024] Example 1

[0025] like Figure 1As shown, the epitaxial deposition apparatus for large-size silicon wafers in this embodiment is similar to conventional chemical vapor deposition (CVD) epitaxial silicon wafer equipment in that it includes a graphite substrate 2 and a nozzle 1 disposed in the middle of the graphite substrate 2. Multiple wafer slots 3 are spaced apart on the graphite substrate 2 for placing silicon wafers. In the epitaxial process, the graphite substrate 2 is heated to a specific process temperature, and reactive gases are ejected through the nozzle 1, causing the epitaxial material to be deposited on the silicon wafer.

[0026] To reduce heat radiation from the high-temperature graphite base 2 towards the nozzle 1, in this embodiment, three layers of heat insulation rings 4 are spaced apart outside the nozzle 1, and the thermal conductivity of the three layers of heat insulation rings 4 decreases sequentially from the outside to the inside. Specifically:

[0027] The outer heat insulation ring 4 is made of silicon carbide with a thermal conductivity of approximately 120 W / m·K. It is used to quickly diffuse the heat radiated by the graphite base 2 laterally, preventing concentrated heat penetration. The middle heat insulation ring 4 is made of graphite with a thermal conductivity of approximately 100 W / m·K, and the inner heat insulation ring 4 is made of foamed quartz with a thermal conductivity of approximately 0.03 W / m·K. These elements form the final heat insulation barrier, preventing residual heat from being transferred to the nozzle 1.

[0028] The thickness of each of the above thermally conductive layers is 5mm. The thermal conductivity of the insulation ring 4 decreases from the outside to the inside, forming a gradient insulation effect to gradually slow down the heat flow. In the silicon wafer deposition process, the thermal radiation of the graphite substrate 2 generates gradient thermal resistance when passing through the multi-layer insulation ring 4. The temperature difference between each layer is significant, which causes the temperature of each layer to drop stepwise, thereby more effectively blocking the heat flow and resulting in a lower temperature of nozzle 1.

[0029] Example 2

[0030] Still Figure 1 As shown, this embodiment is structurally the same as embodiment 1, except that the materials of the middle and inner heat insulation rings 4 are interchanged. In this embodiment, foamed quartz material is used as the middle heat insulation ring 4 to create a heat-blocking layer, forcing heat to be reflected or retained in this layer. Graphite is used as the inner heat insulation ring 4 to homogenize residual heat, avoid local cold zones in nozzle 1, and prevent the condensation and deposition of reactive gases.

[0031] Example 3

[0032] like Figure 2 As shown, in this embodiment, a molybdenum foil (thickness of 0.1m, reflectivity >92%, attached to the inner wall of the heat insulation ring 4 by chemical vapor deposition) is provided on the inner side of the heat insulation ring 4 as a metal reflective layer 5. The high reflectivity reflective layer reflects the thermal radiation back to the base direction, which can directly reduce the radiative heat transfer, and is especially suitable for temperatures above 1500°C.

[0033] Example 4

[0034] like Figure 3 As shown, the heat insulation ring 4 in this embodiment includes a cylindrical ring body 401 and an extension 402 located at the top of the ring body 401. The extension 402 extends outward at a 30° angle. The extension 402 expands the heat radiation shielding area, reduces the direct radiation path of the base to the nozzle 1, and thus further reduces the temperature of the nozzle 1.

Claims

1. An apparatus for epitaxial deposition of large size silicon wafers, comprising a graphite susceptor (2) and a nozzle (1) arranged in the middle of the graphite susceptor (2), characterized in that: A plurality of layers of heat insulation rings (4) are arranged on the graphite base (2) at intervals along the outer periphery of the nozzle (1), and the thermal conductivities of the layers of heat insulation rings (4) are different.

2. The apparatus for epitaxial deposition of large size silicon wafers as claimed in claim 1, wherein: The thermal conductivities of the layers of heat insulation rings (4) decrease in turn from the outside to the inside.

3. The apparatus for epitaxial deposition of large size silicon wafers as claimed in claim 2, wherein: The three layers of heat insulation rings (4) include an outer layer of heat insulation ring (4) made of silicon carbide, a middle layer of heat insulation ring (4) made of graphite, and an inner layer of heat insulation ring (4) made of foamed quartz.

4. The apparatus for epitaxial deposition of large size silicon wafers as claimed in claim 1 wherein: The thermal conductivities of the layers of heat insulation rings (4) are distributed according to the rule that the outer layer is the highest, the middle layer is the lowest, and the inner layer is between the outer layer and the middle layer.

5. The apparatus for epitaxial deposition of large size silicon wafers as claimed in claim 4 wherein: The three layers of heat insulation rings (4) include an outer layer of heat insulation ring (4) made of silicon carbide, a middle layer of heat insulation ring (4) made of foamed quartz, and an inner layer of heat insulation ring (4) made of graphite.

6. The apparatus for epitaxial deposition of a large silicon wafer of any one of claims 1 to 5, wherein: A metal reflecting layer (5) is arranged on the inner side of the heat insulation ring (4).

7. The apparatus for epitaxial deposition of large size silicon wafers as claimed in claim 6, wherein: The metal reflecting layer (5) is made of aluminum foil or molybdenum foil.

8. The apparatus for epitaxial deposition of a large silicon wafer of any one of claims 1-5, wherein: The heat insulation ring (4) includes a cylindrical ring body (401) and an outwardly expanding extension (402) arranged on the upper end of the ring body (401).

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