Silicon oxide film low-temperature atomic layer deposition method based on multiple pulses, film and application
Through the method of deposition of a multi-pulse silicon oxide thin film at low temperature atomic layer, the problem of preparing silicon oxide thin film at high temperature is solved, and the uniform growth and precise thickness control of silicon oxide thin film at low temperature is achieved, reducing equipment complexity and equipment burden.
Patent Information
- Application Number
- CN202410094197.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-01-23
- Publication Date
- 2025-07-25
AI Technical Summary
The prior art When preparing silicon oxide films, high temperature and complex equipment conditions are required, making it difficult to achieve uniform growth and precise thickness control of silicon oxide films at low temperatures.
The low-temperature atomic layer deposition method of multi-pulse silicon oxide film is adopted to control the pulse of inert gas to be sent to the silicon precursor and oxidant O3, and the low-temperature deposition and precise thickness control of the silicon oxide film are achieved, reducing equipment complexity and equipment burden.
Achieve uniform growth and precise thickness control of silicon oxide films at 100-250°C, avoid damage to the substrate with high temperatures, and improve equipment utilization and film uniformity.
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Abstract
Description
Technical Field:
[0001] The present invention relates to a method for low-temperature atomic layer deposition of silicon oxide thin films based on multi-pulses, belonging to the field of nanomaterials. Background Art:
[0002] Silicon oxide has excellent physical and chemical properties such as high chemical stability, excellent insulation, good heat resistance, and mechanical strength, and has a wide range of applications in the fields of microelectronics, optoelectronics, optics, biomedicine, etc. The thickness of the silicon oxide thin film is usually between a few nanometers and several hundred nanometers, and can be designed and controlled according to specific application requirements. In the field of microelectronics, silicon oxide thin films are commonly used to prepare gate oxides of MOS field effect transistors, photolithography mask layers, oxide dielectric layers, etc.; in the field of optoelectronics, silicon oxide thin films can be used to prepare mirrors, thin film filters, etc.; in the field of biomedicine, silicon oxide thin films can be used to prepare biosensors, cell culture vessels, etc.
[0003] To prepare silicon oxide thin films by physical methods, silicon oxide needs to be heated to 1000°C, and traditional chemical vapor deposition (CVD) methods also require heating the silicon source to 400 - 500°C. Using the atomic layer deposition (ALD) method, with aminosilane as the precursor and O3 as the oxidant, silicon oxide thin films can be deposited at a lower temperature. Atomic layer deposition technology realizes the growth of thin films atom by atom layer by using two self-limiting half-reactions, and can achieve uniform growth of thin films on complex surfaces. The ALD technology has the advantages of high controllability, low deposition rate, uniform thickness, low film formation temperature, and low surface roughness. These characteristics make ALD widely used in the preparation of microelectronic devices, nanomaterials, optoelectronic materials, biomedical materials, etc.
[0004] The precursors for ALD deposition of silicon oxide thin films include bis(diethylamino)silane (BDEAS), bis(tert-butylamino)silane (BTBAS), and diisopropylamine silane (DIPAS), etc. Among them, BDEAS and BRBAS often require external plasma assistance to reduce the deposition temperature of the SiO2 thin film. Without plasma or other energy assistance, DIPAS has the lowest deposition temperature. During the deposition process of DIPAS, DIPAS and O3 need to react together in the reaction chamber for a period of time, which requires the reaction chamber to be isolated from the vacuum system, causing the pressure in the reaction chamber to fluctuate in the range of 100 mTorr to greater than 10 Torr. Such a reaction process increases the complexity of the equipment and the burden on the equipment during operation. This is mainly because compared with metal organic complex precursors, the nitrogen-silicon and hydrogen-silicon bonds in the DIPAS structure are more stable.
[0005] Therefore, in order to reduce the deposition temperature, as well as the complexity and burden of the equipment, a new method is needed to deposit silicon oxide thin films and achieve controlled uniform growth of silicon oxide thin films at low temperatures. Summary of the Invention:
[0006] To achieve the above object, the present invention provides a method for precisely controlling the low-temperature deposition thickness of an ALD silicon oxide thin film. This method can precisely control the deposition thickness of the silicon oxide thin film at 100 - 250 °C and reduce the requirements for equipment during the reaction process.
[0007] Specifically, the first object of the present invention is to provide a method for precisely controlling the low-temperature deposition thickness of an ALD silicon oxide thin film, and the method includes the following steps:
[0008] (1) Place the substrate (or called the base) or the device (or called the deposition material) into the reaction chamber of the atomic layer deposition equipment. The reaction chamber is evacuated, and the substrate or the device is heated to a deposition temperature of 100 - 350 °C, and the preferred deposition temperature is 100 - 200 °C;
[0009] (2) Heat the silicon precursor to a stable evaporation temperature to evaporate it, and the temperature range is from room temperature to 100 °C;
[0010] (3) Use an inert atmosphere gas as the purge gas to purge the reaction chamber for 1 - 30 s, and the preferred purge time is 2 - 5 s to increase the deposition rate. The stable flow rate is 5 - 50 sccm, and the preferred flow rate is 10 - 30 sccm. The reaction chamber pressure is 5 - 100 Pa, and the preferred reaction chamber pressure is 10 - 20 Pa to reduce the impurities in the thin film;
[0011] (4) Use an inert gas as the carrier gas to send the silicon precursor into the reaction chamber of the atomic layer deposition equipment in a pulsed manner. The pulse time is 0.01 - 3 s, and the preferred pulse time is 0.01 - 1 s. At this time, the reaction chamber pressure is 10 - 500 Pa, and the preferred reaction chamber pressure is less than 10 - 100 Pa. The precursor concentration in the reaction chamber is 0.1 - 10 mg / L, and the preferred precursor concentration is 0.1 - 1 mg / L. The precursor forms chemisorption on the surface of the substrate or the deposition material to complete the first half-reaction;
[0012] (5) Use an inert gas to purge the reaction chamber of the atomic layer deposition equipment for 1 - 30 s, and the preferred purge time is less than 5 s. The stable flow rate is 5 - 50 sccm, the reaction chamber pressure is 5 - 100 Pa, and the preferred flow rate is 10 - 30 sccm, and the preferred reaction chamber pressure is 10 - 100 Pa;
[0013] (6) Feed O3 into the reaction chamber of the atomic layer deposition equipment in a pulsed manner. The pulsed time for O3 introduction is 0.01 - 1 s, preferably 0.01 - 0.05 s. At this time, the pressure in the reaction chamber is 10 - 500 Pa, preferably 10 - 100 Pa. The concentration of O3 in the reaction chamber is 0.001 - 1 mg / L, preferably 0.01 - 0.02 mg / L. The O3 pulse is 1 - 30 times, preferably 15 - 20 times. After each pulse of O3 introduction, the reaction chamber is purged with an inert atmosphere gas. The purging time is 1 - 30 s, preferably 2 - 10 s, to discharge the excessive O3 molecules from the reaction chamber. During the introduction of O3 and purging process, the stable purging gas flow rate is 5 - 50 sccm, and the reaction chamber pressure is 5 - 100 Pa, preferably the flow rate is 10 - 30 sccm, and preferably the reaction chamber pressure is 10 - 20 Pa, to complete the second half-reaction;
[0014] (7) Steps (4) - (6) form a reaction cycle. Repeat the reaction cycle of steps (4) - (6) more than 1 time to obtain a silicon oxide thin film with the desired target thickness.
[0015] Furthermore, the substrate described in step (1) includes but is not limited to materials such as silicon, silicon oxide, gallium arsenide, etc.; the substrate temperature is 100 - 350 °C, preferably 100 - 200 °C.
[0016] Furthermore, the precursor described in step (2) can be a precursor that is difficult to react at low temperature for atomic layer deposition of other elements such as germanium and gallium. The evaporation temperature of the precursor is from the liquefaction temperature of the precursor to the boiling point temperature + 10 °C.
[0017] Furthermore, the precursor described in step (2) includes but is not limited to one or more of bis(diethylamino)silane (BDEAS), bis(tert-butylamino)silane (BTBAS), and diisopropylamine silane (DIPAS), etc. The preferred temperature of the precursor is 10 °C lower than the boiling point of the precursor.
[0018] Furthermore, when introducing the precursor in step (4), the reaction chamber pressure is 5 - 100 Pa, preferably 10 - 20 Pa. The concentration of the precursor in the reaction chamber is 0.1 - 10 mg / L, preferably 0.1 - 1 mg / L.
[0019] Furthermore, the deposition thickness per ALD cycle (GPC) is controlled by the number of repetitions of the O3 pulse in step (6), usually 1 - 30 times, preferably 20 times. The O3 pulse time and the reaction chamber pressure during the pulse process in step (6) are the same for 2 or more times.
[0020] Further, the O3 pulse in step (6) includes introducing O3 into the reaction chamber in a pulsed manner by means of being carried by an inert gas as a carrier gas or directly introducing without a carrier gas. The time for introducing O3 in each pulse is 0.01 - 1 s, preferably the pulse time is less than 0.05 s. At this time, the pressure in the reaction chamber is less than 500 Pa, preferably the pressure in the reaction chamber is less than 100 Pa, and the O3 concentration in the reaction chamber is 0.001 - 1 mg / L, preferably the concentration is 0.01 - 0.02 mg / L.
[0021] For the silicon precursor of atomic layer deposition, its reaction activity is relatively low, and the oxidant O3 decomposes relatively fast at a relatively high temperature. O3 is supplied in multiple pulses, which can achieve a relatively high concentration of reaction activity, thereby achieving a relatively low reaction temperature. In addition, the process of multiple O3 pulses can adjust the deposition thickness per cycle (GPC) of the thin film by controlling the oxidation time.
[0022] The inert atmosphere gas is one or more of inert gases such as nitrogen or helium.
[0023] The application of the silicon oxide thin film prepared by the low-temperature atomic layer deposition method of silicon oxide based on multiple pulses in optical thin films, metal oxide semiconductor devices (MOS) or solar thin films.
[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0025] (1) The present invention can effectively reduce the temperature of the atomic layer deposition of SiO2 thin film, and avoid damage to the substrate or device caused by high temperature.
[0026] (2) The present invention can effectively reduce the equipment burden caused by the long-term reaction of the silicon precursor and O3.
[0027] (3) The present invention can control and adjust the deposition thickness per cycle (GPC) of atomic layer deposition, can effectively improve the utilization rate of the precursor, and can more precisely adjust the deposition thickness of the thin film. Description of the Drawings
[0028] Figure 1 : GPC of silicon oxide at different pulse numbers when DIPAS is used as the precursor in Example 1.
[0029] Specific implementation method:
[0030] The following provided examples are not intended to limit the scope covered by the present invention, and the described steps are not intended to limit their execution order. The described directions are limited to the drawings. Obvious improvements made by those skilled in the art to the present invention in combination with the existing common general knowledge also fall within the protection scope required by the present invention.
[0031] Example 1:
[0032] Using a 10-cm-diameter circular single-crystalline silicon sheet as the substrate, after cleaning the surface with a mixed solution of alcohol and 2M hydrochloric acid (volume ratio 1:1), it is placed in the laminar-flow vacuum reaction chamber of the atomic layer deposition equipment. The cylindrical reaction chamber has a diameter of 30 cm and a height of 1 cm, and the substrate is heated to 250 °C. Nitrogen is used as the purge gas and carrier gas, with a flow rate of 20 sccm, and the reaction chamber pressure is 10 Pa; DIPAS is heated to 35 °C.
[0033] The reaction cycle process is as follows: for the first half-reaction, a 0.1-s DIPAS pulse is carried by the carrier gas N2 with a flow rate of 20 sccm and pulsed into the reaction chamber. At this time, the reaction chamber pressure is 50 Pa (the precursor concentration in the reaction chamber is 0.2 mg / L), and the excess precursor is purged with N2 for 20 s with a flow rate of 20 sccm; for the second half-reaction, a 0.015-s O3 pulse is carried by the carrier gas N2 with a flow rate of 20 sccm and pulsed into the reaction chamber. At this time, the reaction chamber pressure is 100 Pa (the O3 concentration in the reaction chamber is 0.01 mg / L), and the excess O3 is purged with N2 for 10 s with a flow rate of 20 sccm. The number of repetitions of the O3 introduction and purge processes in each reaction cycle is as Figure 1 shown, which are 2, 5, 10, 12, 20, 25, 30. The reaction chamber pressure during the N2 purge process is 10 Pa.
[0034] A total of 100 reaction cycles are deposited for the reaction. The thickness and uniformity of the thin film are measured by X-ray reflectivity (XRR).
[0035] Example 2:
[0036] Using a 10-cm-diameter circular single-crystalline silicon sheet as the substrate, after cleaning the surface with a mixed solution of alcohol and 2M hydrochloric acid (volume ratio 1:1), it is placed in the laminar-flow vacuum reaction chamber of the atomic layer deposition equipment. The reaction chamber has a diameter of 30 cm and a height of 1 cm, and the substrate is heated to 150 °C. Nitrogen is used as the purge gas and carrier gas, with a flow rate of 10 sccm, and the reaction chamber pressure is 5 Pa; DIPAS is heated to 35 °C.
[0037] The reaction cycle process is as follows: for the first half-reaction, a 0.1-s DIPAS pulse is carried by the carrier gas N2 with a flow rate of 10 sccm and pulsed into the reaction chamber. At this time, the reaction chamber pressure is 30 Pa (the precursor concentration in the reaction chamber is 0.2 mg / L), and the excess precursor is purged with N2 for 20 s with a flow rate of 10 sccm; for the second half-reaction, a 0.015-s O3 pulse is carried by the carrier gas N2 with a flow rate of 10 sccm and pulsed into the reaction chamber. At this time, the reaction chamber pressure is 70 Pa (the O3 concentration in the reaction chamber is 0.01 mg / L), and the excess O3 is purged with N2 for 10 s with a flow rate of 10 sccm. The number of repetitions of the O3 introduction and purge processes in each reaction cycle is as Figure 1 shown. The reaction chamber pressure during the N2 purge process is 10 Pa.
[0038] The reaction co - deposition was carried out for 200 reaction cycles. The thickness and uniformity of the thin film were measured by X - ray reflectometry (XRR).
[0039] Comparative Example 1:
[0040] Using a circular single - crystal silicon sheet with a diameter of 10 cm as the substrate, after cleaning the surface with a mixed solution of alcohol and 2M hydrochloric acid (volume ratio 1:1), it was placed in the laminar flow vacuum reaction chamber of the atomic layer deposition equipment. The reaction chamber had a diameter of 30 cm and a height of 1 cm, and the substrate was heated to 150 °C. Nitrogen was used as the purge gas and carrier gas with a flow rate of 20 sccm, and the reaction chamber pressure was 10 Pa; DIPAS was heated to 35 °C.
[0041] During the reaction cycle process, for the first half - reaction, a 0.5 - s DIPAS pulse was carried by the carrier gas N2 and pulsed into the reaction chamber with a carrier gas flow rate of 10 sccm. The reaction chamber was isolated from the vacuum pumping system. At this time, the reaction chamber pressure was 1500 Pa (the precursor concentration in the reaction chamber was 1 mg / L), the pressure was maintained for 5 s, and the excess precursor was purged with 20 s of N2 with a flow rate of 20 sccm; for the second half - reaction, a 2 - s O3 pulse was carried by the carrier gas N2 and pulsed into the reaction chamber with a carrier gas flow rate of 10 sccm. The reaction chamber was isolated from the vacuum pumping system. At this time, the reaction chamber pressure was 2000 Pa (the O3 concentration in the reaction chamber was 0.1 mg / L), the pressure was maintained for 10 s, and the excess O3 was purged with 10 s of N2 with a flow rate of 20 sccm. The reaction chamber pressure during the purge process was 10 Pa.
[0042] The reaction co - deposition was carried out for 100 reaction cycles. The thickness and uniformity of the thin film were measured by X - ray reflectometry (XRR).
[0043] For the thin film prepared in Example 1, the thickness and uniformity of the thin film were measured by X - ray reflectometry. When the number of O3 pulses was 5 times, on a silicon substrate with a diameter of 10 cm, the average thickness of the thin film was 13.4 nm, and the growth per cycle (GPC) was Per cycle, the thickness range was measured at 20 sampling points on the surface, which was 13.1 - 13.7 nm. As shown in the appendix Figure 1 By changing the number of O3 pulses in each cycle to 2, 5, 10, 12, 20, 25, 30, the GPC can be linearly changed from increased to
[0044] For the thin film prepared in Example 2, the thickness and uniformity of the thin film were measured by X - ray reflectometry. On a silicon substrate with a diameter of 10 cm, the average thickness of the thin film was 44.8 nm, and the growth per cycle (GPC) was Per cycle, the thickness range was measured at 20 sampling points on the surface, which was 44.2 - 45.3 nm.
[0045] For the film prepared in Comparative Example 1, X-ray reflection was used to measure the thickness and uniformity of the film. On a silicon substrate with a diameter of 10 cm, the average thickness of the film was 7.4 nm, and the growth per cycle (GPC) was For each cycle, the thickness range of 7.0 - 7.7 nm was measured at 20 sampling points on the surface.
[0046] It can be seen from Example 1 that when DIPAS is used as the precursor, there is a strong linear relationship between the number of pulses and the GPC of the film, which ensures the repeatability of this method and the uniformity of the prepared film. In Example 2, a relatively high GPC was also achieved at a lower temperature of 150 °C. This method is of great significance in related industries that require low-temperature deposition of SiO2 films. Comparing Examples 1 - 2 with Comparative Example 1, while ensuring a relatively high GPC at a lower temperature, the burden on the equipment caused by the reaction pressure is relatively small in the present invention.
[0047] It has been experimentally confirmed that, as described in the present invention, during the process of atomic layer deposition for preparing silicon oxide films, by using the method of multiple O3 pulses, the reaction temperature can be reduced, the burden on the equipment and the complexity of the system can be decreased. As shown in the attached drawings, controlling the number of pulses can control the GPC of the growth of silicon oxide, which is of great significance for the growth of nanomaterials and can ensure the uniformity of the film at the same time.
[0048] Although the present invention has been disclosed above with examples, it is not intended to limit the present invention. Anyone familiar with this technology can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be defined by the claims.
Claims
1. A low-temperature atomic layer deposition method for silicon oxide thin films based on multi-pulses, characterized in that, The method includes the following specific steps: (1) Place the substrate (or called the base) or device (or called the deposition material) into the reaction chamber of the atomic layer deposition equipment. Evacuate the reaction chamber, heat the substrate or device to a deposition temperature of 100 - 350 °C, and the preferred deposition temperature is 100 - 200 °C; (2) Heat the silicon precursor to a stable evaporation temperature for evaporation, with the temperature range from room temperature to 100 °C; (3) Use an inert atmosphere gas as the purge gas to purge the reaction chamber for 1 - 30 s, and the preferred purge time is 2 - 5 s, to increase the deposition rate. The stable flow rate is 5 - 50 sccm, and the preferred flow rate is 10 - 30 sccm. The reaction chamber pressure is 5 - 100 Pa, and the preferred reaction chamber pressure is 10 - 20 Pa, to reduce impurities in the thin film; (4) Use an inert atmosphere gas as the carrier gas to send the silicon precursor into the reaction chamber of the atomic layer deposition equipment in a pulsed manner. The pulse time is 0.01 - 3 s, and the preferred pulse time is 0.01 - 1 s. At this time, the reaction chamber pressure is 10 - 500 Pa, and the preferred reaction chamber pressure is less than 10 - 100 Pa. The precursor concentration in the reaction chamber is 0.1 - 10 mg / L, and the preferred precursor concentration is 0.1 - 1 mg / L. The precursor forms chemisorption on the surface of the substrate or device, completing the first half - reaction; (5) Use an inert atmosphere gas to purge the reaction chamber of the atomic layer deposition equipment for 1 - 30 s, and the preferred purge time is less than 5 s. The stable flow rate is 5 - 50 sccm, the reaction chamber pressure is 5 - 100 Pa, and the preferred flow rate is 10 - 30 sccm, and the preferred reaction chamber pressure is 10 - 100 Pa; (6) Send O3 into the reaction chamber of the atomic layer deposition equipment in a pulsed manner. The pulse time for O3 introduction is 0.01 - 1 s, and the preferred pulse time is 0.01 - 0.05 s. At this time, the reaction chamber pressure is 10 - 500 Pa, and the preferred reaction chamber pressure is 10 - 100 Pa. The O3 concentration in the reaction chamber is 0.001 - 1 mg / L, and the preferred concentration is 0.01 - 0.02 mg / L; The O3 pulse is 1 - 30 times, and the preferred number of pulses is 15 - 20 times. After each pulse of O3 introduction, the reaction chamber is purged with an inert atmosphere gas, and the purge time is 1 - 30 s, and the preferred purge time is 2 - 10 s, to exhaust the excess O3 molecules from the reaction chamber; During the introduction of O3 and the purge process, the stable purge gas flow rate is 5 - 50 sccm, and the preferred flow rate is 10 - 30 sccm. The reaction chamber pressure is 5 - 100 Pa, and the preferred reaction chamber pressure is 10 - 20 Pa, completing the second half - reaction; (7) Steps (4) - (6) form a reaction cycle. Repeat steps (4) - (6) for more than 1 reaction cycle to obtain a silicon oxide thin film with the desired target thickness.
2. The method according to claim 1, characterized in that, The number of repetitions of the O3 pulse in step (6) is usually 1 - 30 times, and the preferred number of pulses is 15 - 20 times, to control the deposition thickness per ALD cycle (GPC); The O3 pulse time and the reaction chamber pressure during the pulse process are the same for 2 or more times in step (6).
3. The preparation method according to claim 1 or 2, characterized in that, Step (6): The O3 pulse includes introducing O3 into the reaction chamber in a pulsed manner by means of being carried by an inert atmosphere gas as a carrier gas or directly introducing without a carrier gas. The time for introducing O3 in each pulse is 0.01 - 1 s, preferably 0.01 - 0.05 s. At this time, the reaction chamber pressure is 10 - 500 Pa, preferably 10 - 100 Pa, and the O3 concentration in the reaction chamber is 0.001 - 1 mg / L, preferably 0.01 - 0.02 mg / L.
4. The method according to claim 1, characterized in that, When introducing the precursor in step (4), the reaction chamber pressure is 5 - 100 Pa, preferably 10 - 20 Pa, and the precursor concentration in the reaction chamber is 0.1 - 10 mg / L, preferably 0.1 - 1 mg / L.
5. The method according to claim 1, wherein The precursor described in step (2) includes, but is not limited to, one or more of bis(diethylamino)silane (BDEAS), bis(tert-butylamino)silane (BTBAS), and diisopropylamine silane (DIPAS), etc. The evaporation temperature of the precursor is from the liquefaction temperature of the precursor to the boiling point temperature + 10 °C, and the preferred temperature of the precursor is 10 - 20 °C higher than the liquefaction temperature.
6. The method according to claim 1, wherein The precursor described in step (2) can be one or more precursors for atomic layer deposition of other elements such as germanium and gallium, which are difficult to react at low temperatures. The evaporation temperature of the precursor is from the liquefaction temperature of the precursor to the boiling point temperature + 10 °C.
7. The method according to claim 1, characterized in that The substrate described in step (1) includes, but is not limited to, one or more of materials such as silicon, silicon oxide, and gallium arsenide, etc.; the substrate temperature is 100 - 350 °C, preferably 100 - 200 °C; step (1) preferably uses a laminar flow reaction chamber, and the reaction chamber is evacuated to a reaction chamber pressure less than or equal to 100 Pa.
8. The method according to claim 1 or 3, characterized in that, The inert atmosphere gas is one or more of inert gases such as nitrogen or helium.
9. A silicon oxide thin film obtained by the method according to any one of claims 1 - 8.
10. An application of the thin film according to claim 9 as an optical thin film, a metal oxide semiconductor device (MOS), or a solar thin film.