A quartz nozzle suitable for polycrystalline silicon deposition on 300mm silicon wafers

Abstract

This utility model discloses a quartz nozzle suitable for polycrystalline silicon deposition on 300mm silicon wafers. The quartz nozzle is characterized by: an L-shaped tube; rounded corners at the bends; a uniform inner diameter; integral molding of quartz material; and a fully inclined outlet end with an angle ∠B of 40 to 50 degrees. The quartz nozzle provided in this application improves the uniformity of polycrystalline silicon deposition thickness on 300mm heavily doped silicon wafers and increases nozzle lifespan.

Description

Technical Field

[0001] This utility model belongs to the field of semiconductor manufacturing technology, specifically relating to a quartz nozzle suitable for polycrystalline silicon deposition on 300mm silicon wafers. Background Technology

[0002] With the rapid development of the global semiconductor industry, the trend of continuously shrinking device feature sizes and expanding substrate sizes has placed unprecedentedly stringent requirements on silicon wafer quality. In the manufacturing process of nanoscale integrated circuits, despite increasingly sophisticated technology, trace amounts of harmful impurities are still unintentionally introduced, leading to significant degradation in device electrical performance. Therefore, constructing clean areas free from oxygen deposits and metallic impurity defects has become a core objective for improving silicon wafer surface quality.

[0003] As an advanced external gettering technology, the polysilicon gettering mechanism utilizes the abundant grain boundaries within the polysilicon layer as efficient impurity absorption centers, achieving impurity capture in the early stages of the process. Notably, the polysilicon deposition process temperature closely matches the oxygen nucleation temperature in silicon. This characteristic allows for the induction of oxygen precipitation within the silicon wafer during polysilicon deposition, further purifying the wafer through an internal gettering effect. This synergistic effect of internal and external gettering creates an "enhanced gettering" mechanism that significantly expands the clean area on the silicon wafer surface, providing crucial support for the manufacturing of high-end integrated circuits such as Ultra Large Scale IC (ULSI) and Very Large Scale Integration (VLSI).

[0004] With its unique "dual getter" function, polycrystalline silicon getter technology has become the mainstream solution for controlling the cleanliness of substrate silicon wafers, demonstrating irreplaceable advantages in ensuring device reliability and yield. By precisely controlling deposition parameters, this technology can construct defect-free clean interfaces at the nanoscale, driving the continuous evolution of semiconductor processes towards higher integration and performance limits.

[0005] In the semiconductor manufacturing field, low-pressure chemical vapor deposition (LPCVD) is one of the key methods for preparing polycrystalline silicon thin films. This technology typically uses pure silane gas as a raw material and performs deposition within a temperature range of 600°C to 680°C, with the reaction pressure controlled between 100 and 400 mTorr. The low-pressure environment increases the mean free path and diffusion constant of the reactant gas, thereby reducing gas consumption and improving the thickness uniformity of the thin film on the substrate. Furthermore, the temperature control method of LPCVD is simple, ensuring uniform heating of the substrate and significantly improving the reliability and quality of the thin film.

[0006] In the field of polycrystalline silicon deposition, vertical furnaces are the mainstream equipment and are widely used in LPCVD processes. The specific process flow includes: wafer loading → chamber vacuuming → leak detection → heating → pipeline purging → polycrystalline silicon deposition → post-deposition pipeline purification → vacuum breaking → wafer unloading. In the critical steps of polycrystalline silicon deposition, the reactive gas enters the reaction chamber through a precisely designed quartz nozzle. The nozzle's design not only affects its own lifespan but also directly impacts the deposition quality of the polycrystalline silicon film. Defective nozzle design can easily lead to clogging, affecting nozzle lifespan and the uniformity of the deposited film. Utility Model Content

[0007] The purpose of this invention is to provide a quartz nozzle suitable for polycrystalline silicon deposition on 300mm silicon wafers to address the shortcomings of existing technologies. This nozzle aims to improve the uniformity of polycrystalline silicon film thickness distribution and extend the service life of the nozzle, thereby optimizing the deposition process and improving production efficiency and product quality.

[0008] The objective of this utility model is achieved through the following technical solution:

[0009] A quartz nozzle suitable for polycrystalline silicon deposition on 300mm silicon wafers, wherein the quartz nozzle is an L-shaped tube and the bends of the quartz nozzle are rounded.

[0010] The quartz nozzles have equal overall inner diameters; the quartz nozzles are integrally molded from quartz material.

[0011] The outlet end of the quartz nozzle is set at a full tilt, with a tilt angle ∠B of 40 degrees to 50 degrees.

[0012] Preferably, the overall wall thickness of the quartz nozzle is equal.

[0013] Preferably, the purity of the quartz material is ≥99.99%.

[0014] Preferably, the inner surface roughness Ra of the quartz nozzle is ≤0.4 μm.

[0015] Preferably, the inner surface of the quartz nozzle is fire-polished.

[0016] Preferably, the air inlet end of the quartz nozzle is sealed to the air source interface using a sealing ring.

[0017] The quartz nozzle provided in this application improves the uniformity of polycrystalline silicon deposition film thickness on a 300mm heavily doped silicon wafer and increases the nozzle's service life. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the quartz nozzle provided in a preferred embodiment of this application;

[0019] Figure 2 yes Figure 1 A magnified schematic diagram of the N parts;

[0020] Figure 3 This is a structural schematic diagram of a quartz nozzle provided by a related technology;

[0021] Figure 4 yes Figure 3 Enlarged schematic diagram of part M;

[0022] Figure 5 Is it adopted as Figure 1 The diagram shows a quartz nozzle for film thickness uniformity testing.

[0023] Figure 6 Is it adopted as Figure 3 The diagram shows a quartz nozzle for film thickness uniformity testing.

[0024] Figure 7 Is it adopted as Figure 1 The diagram shows the outlet end of the quartz nozzle after the deposition thickness is greater than 15 μm.

[0025] Figure 8 Is it adopted as Figure 3 The diagram shows the outlet end of the quartz nozzle after the deposition thickness is greater than 15 μm.

[0026] Explanation of reference numerals in the attached figures:

[0027] 1-Inlet end; 2-Outlet end; 3-Rounded corner; 4-Interface. Detailed Implementation

[0028] This application provides a quartz nozzle suitable for polycrystalline silicon deposition on 300mm silicon wafers, such as... Figures 1-2 As shown, the quartz nozzle is an L-shaped round tube, which allows the tube diameter to fit more closely to the inner wall of the vertical furnace cavity. The bends of the quartz nozzle are rounded at 3°, allowing the gas to turn smoothly, preventing gas from accumulating in dead corners, and also preventing stress concentration that could lead to breakage.

[0029] The overall inner diameter of the quartz nozzle is constant. Generally, such as... Figures 3-4As shown, the inner diameter A2 of the nozzle outlet 2 is smaller than the inner diameter A1 of the inlet 1 (the silicon source gas enters the nozzle from the inlet 1 and then exits from the outlet 2 into the vertical furnace cavity) to increase the gas output rate and avoid excessive local gas concentration causing deposition. However, the applicant has found in practice that the 300mm silicon wafer is relatively large, and the deposition rate is relatively higher than that of smaller silicon wafers. Correspondingly, the silicon source gas input is also larger, and the temperature at the nozzle outlet is also higher. The silicon source gas is prone to react and deposit at this point. If the inner diameter of the outlet is small and the pipe diameter is thin, the nozzle is easily clogged, affecting the nozzle's service life. This application sets the inner diameter B2 of the nozzle outlet 2 to be the same as the inner diameter B1 of the inlet 1. Compared with conventional technology, this increases the pipe diameter at the outlet, thereby promoting gas diffusion and preventing nozzle clogging caused by the thin pipe diameter at the outlet.

[0030] Preferably, the overall wall thickness of the quartz nozzle is also equal.

[0031] As mentioned above, conventional technologies require an interface 4 for transitional connection between the inlet and outlet sections due to the different pipe diameters at the inlet and outlet ends. This interface necessitates welding or other methods to connect the inlet and outlet sections, which can lead to structural instability and leakage under prolonged high-temperature applications. In contrast, this application utilizes an inlet 1 and outlet 2 with equal pipe diameters, allowing the entire quartz nozzle to be integrally molded without welding. This maximizes structural stability and prevents fractures caused by defects or stress at the weld joints. The nozzle is made of quartz, preferably high-purity quartz (purity ≥ 99.99%). Its low metal impurity characteristics (Fe ≤ 1 ppb, Al ≤ 1 ppb) effectively prevent contamination of the silicon wafer surface by transition metal ions. This quartz material exhibits excellent thermal stability within a deposition temperature range of 500–800°C, ensuring uniform gas transport and significantly improving the electrical performance and device yield of polycrystalline silicon thin films by suppressing the formation of metal precipitates.

[0032] The outlet end 2 of the quartz nozzle in this application is fully inclined (i.e., fully angled), with an inclination angle ∠B of 40 to 50 degrees. A typical related technology sets the outlet end as a semi-angled opening (half of the outlet is angled, and the other half is horizontal), with a smaller inclination angle ∠A, such as 30 degrees. Figures 3-4 As shown, a semi-sloping nozzle allows for adjustment of the gas outlet direction, and while adjusting the outlet direction, it minimizes the impact on the gas flow rate. However, as analyzed above, if a semi-sloping nozzle is used, the gas outlet area is still relatively small, making it prone to nozzle clogging. Therefore, this application uses a fully sloping nozzle with a larger tilt angle to maximize the diffusion area of ​​the gas entering the cavity, improve the uniformity of gas distribution within the cavity, and thus enhance the uniformity of the polycrystalline silicon deposited thin film.

[0033] Preferably, the inner surface roughness Ra of the quartz nozzle is ≤0.4 μm. The interior of the quartz nozzle can be smoothed using methods such as flame polishing to achieve an ultra-smooth surface, reducing particle sources, inhibiting gas molecule nucleation on its surface, and further reducing nozzle clogging.

[0034] Preferably, the air inlet end of the quartz nozzle is sealed to the air source interface (specifically the machine tool pipeline interface) with an O-ring to ensure its airtightness and prevent air leakage, and to facilitate disassembly and installation.

[0035] The length of the quartz nozzle provided in this application can be adjusted according to actual conditions. Preferably, four length dimensions are provided, distributed in different height areas of the vertical furnace tube, to ensure that the gas is effectively guided to the target area and to achieve consistency of film thickness in the vertical direction of the furnace tube.

[0036] Practice has shown that using the methods provided in this application, such as... Figure 1 The quartz nozzle shown is compared to... Figure 3 The quartz nozzles shown (two quartz nozzles of equal length and equal inlet diameter) at a deposition temperature of 650℃, when the polycrystalline silicon deposition thickness is... At times, such as Figures 5-6 As shown, uniformity can be improved from about 5% to below 2%.

[0037] Adopting such Figure 3 The quartz nozzle shown has a lifespan of 15µm (for the cumulative deposition thickness of polycrystalline silicon). Beyond 15µm, as... Figure 8 As shown, polysilicon buildup occurred at the nozzle outlet, rendering it unusable. The method described in this application... Figure 1 The quartz nozzle shown exceeds 15µm, as... Figure 7 As shown, there is no polysilicon accumulation / blockage abnormality at the nozzle outlet, and the lifespan can be extended to 30um.

[0038] Therefore, the quartz nozzle provided in this application improves the uniformity of the polycrystalline silicon deposition film thickness on a 300mm heavily doped silicon wafer and increases the nozzle's service life.

[0039] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the present invention. Clearly, those skilled in the art can make various alterations and modifications to the present invention without departing from its spirit and scope. Thus, if such modifications and modifications fall within the scope of the claims of the present invention and their equivalents, the present invention also intends to include such modifications and modifications.

Claims

1. A quartz nozzle suitable for polysilicon deposition on 300 mm silicon wafers, characterized in that, The quartz nozzle is an L-shaped tube; the bends of the quartz nozzle are rounded. The quartz nozzles have equal overall inner diameters; the quartz nozzles are integrally molded from quartz material. The outlet end of the quartz nozzle is set at a full tilt, with a tilt angle ∠B of 40 degrees to 50 degrees.

2. The quartz nozzle for polycrystalline silicon deposition on a 300mm silicon wafer as described in claim 1, characterized in that, The overall wall thickness of the quartz nozzles is equal.

3. The quartz nozzle for polycrystalline silicon deposition on a 300mm silicon wafer as described in claim 1, characterized in that, The purity of the quartz material is ≥99.99%.

4. The quartz nozzle for polycrystalline silicon deposition on a 300mm silicon wafer as described in claim 1, characterized in that, The inner surface roughness Ra of the quartz nozzle is ≤0.4um.

5. The quartz nozzle for polycrystalline silicon deposition on a 300mm silicon wafer as described in claim 4, characterized in that, The inner surface of the quartz nozzle is fire-polished.

6. The quartz nozzle for polycrystalline silicon deposition on a 300mm silicon wafer as described in claim 1, characterized in that, The air inlet end of the quartz nozzle is sealed to the air source interface with a sealing ring.

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