A method of depositing a doped silicon oxide film and a vapor deposition apparatus

Abstract

The present application belongs to the technical field of semiconductor production, and relates to a method for depositing a doped silicon oxide film and a vapor deposition device. The method comprises the following steps: (1) introducing a doped element precursor, allowing it to decompose and be adsorbed on the surface of a substrate, and then performing a first purge; (2) introducing a silicon precursor, allowing it to be adsorbed on the surface of the substrate, and then performing a second purge; (3) allowing an oxygen source to react with the decomposition product of the doped element precursor and the silicon precursor, and then performing a third purge; and repeating steps (1) to (3) until a doped silicon oxide film of a target thickness is formed on the surface of the substrate. The present application allows the doped element precursor to decompose, and the decomposition product to react with the silicon precursor and the oxygen source, thereby promoting the deposition of the doped silicon oxide film on the substrate, achieving the deposition of the doped silicon oxide film by means of thermal ALD, and also enabling the deposition of the doped silicon oxide film by means of plasma-enhanced ALD.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and more specifically to a method for depositing doped silicon oxide thin films and a vapor deposition apparatus. Background Technology

[0002] With the continuous improvement of chip integration, high aspect ratio FinFETs have become a key technology in 7nm node processes. Doping with phosphorus or boron is an indispensable step in FinFET manufacturing. In traditional processes, phosphorus or boron doping is typically achieved using ion implantation, but this method faces numerous challenges at 7nm and below nodes. First, as FinFET dimensions shrink, lattice damage caused by ion implantation becomes increasingly severe and difficult to avoid. Second, with a reasonable ion implantation mask height, the extremely small spacing between the N-type and P-type regions limits the implantation tilt angle to within 7°, significantly increasing the process difficulty. Furthermore, the controllability of the short-channel effect restricts the maximum permissible ion implantation energy, making it extremely difficult to dope the bottom region of the FinFET at a small angle.

[0003] To address the problems associated with ion implantation, the industry has proposed using annealing to allow phosphorus or boron to enter FinFETs. Typically, this involves first depositing a layer of phosphorus-doped silicate glass (PSG) or boron-doped silicate glass (BSG) on a substrate using chemical vapor deposition (CVD). Then, a protective layer is deposited on the PSG or BSG to prevent phosphorus or boron loss during annealing. Finally, annealing allows the phosphorus from the PSG or the boron from the BSG to thermally enter the substrate, thus achieving phosphorus or boron doping in the silicon substrate. This method effectively avoids the problems inherent in ion implantation.

[0004] For advanced manufacturing processes, as chip dimensions continue to shrink, traditional CVD-deposited thin films can no longer meet the device's requirements for conformality and step coverage. Atomic layer deposition (ALD) methods are therefore necessary to deposit PSG or BSG thin films. Thermal ALD and plasma-enhanced atomic layer deposition are among the more commonly used ALD methods.

[0005] Currently, thermal ALD processes cannot be used to deposit PSG or BSG thin films.

[0006] Although research has been conducted on plasma-enhanced ALD (AAL) deposition of PSG thin films, as chip sizes decrease and device structures become more complex, uneven plasma distribution in the AAL process can easily lead to inconsistencies in film thickness and composition, affecting conformability. Furthermore, some phosphorus-containing precursors are difficult to react with in the AAL process, making it impossible to prepare PSG thin films using these precursors. This indicates that current AAL processes struggle to produce PSG or BSG thin films with high conformability, and the choice of precursors is limited.

[0007] In summary, there is an urgent need to provide a method for depositing PSG or BSG thin films to overcome the limitations of traditional processes. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a method and vapor deposition apparatus for depositing doped silicon oxide thin films, which enables the deposition of doped silicon oxide thin films using thermal ALD, and the method can also be used to deposit doped silicon oxide thin films using plasma-enhanced ALD.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a method for depositing a doped silicon oxide thin film, the method comprising the following steps:

[0011] (1) Introduce the precursor of the doped element, thermally decompose it and adsorb it onto the substrate surface, and then perform the first purging;

[0012] (2) Introduce the silicon precursor to adsorb onto the substrate surface, and then perform a second purging;

[0013] (3) The oxygen source reacts with the decomposition products of the doped element precursor and the silicon precursor in an oxidation reaction, followed by a third purging.

[0014] Repeat steps (1) to (3) until a doped silicon oxide film of the target thickness is formed on the substrate surface.

[0015] The method for depositing doped silicon oxide thin films provided by this invention involves the thermal decomposition of the dopant precursor, followed by a reaction between the decomposed product and a silicon precursor and an oxygen source, thereby depositing the doped silicon oxide thin film on a substrate. This method enables the deposition of doped silicon oxide thin films using thermal ALD, and it can also be used for plasma-enhanced ALD, thus broadening the range of precursors that can be selected in plasma-enhanced ALD processes.

[0016] Preferably, before introducing the dopant precursor in step (1), the reaction temperature is controlled to be no lower than the thermal decomposition temperature of the dopant precursor.

[0017] Preferably, the reaction temperature is 320-340℃, for example, it can be 320℃, 325℃, 330℃, 335℃ or 340℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0018] Preferably, before introducing the doped element precursor in step (1), the reaction pressure is controlled to be 1.5-2.5 Torr, for example, it can be 1.5 Torr, 1.8 Torr, 2 Torr, 2.2 Torr or 2.5 Torr, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] Preferably, the dopant precursor in step (1) includes a phosphorus precursor or a boron precursor.

[0020] The phosphorus precursors include phosphine and / or phosphate ester compounds.

[0021] The boron precursors include boranes and / or borate esters.

[0022] When the dopant precursor is a phosphorus precursor, a PSG film of the target thickness is formed on the substrate surface; when the dopant precursor is a boron precursor, a BSG film of the target thickness is formed on the substrate surface.

[0023] Preferably, the phosphate ester compound includes triethyl phosphate and / or trimethyl phosphite. Preferably, the borate ester compound includes triethyl borate and / or trimethyl borate.

[0024] It should be noted that the present invention does not specifically limit the introduction time of the doped element precursor in step (1) and the introduction time of the silicon precursor in step (2). Those skilled in the art can make adaptive adjustments according to the usage scenario and application conditions. The present invention does not specifically limit the time of the first purging in step (1), the time of the second purging in step (2) and the time of the third purging in step (3) in order to achieve the required cleanliness of the substrate surface and meet the requirements of the next deposition.

[0025] Step (1) The first purging can remove excess doped precursors and decomposition products; Step (2) The second purging can remove excess silicon precursors; Step (3) The third purging can remove byproducts generated by the oxidation reaction and excess reactants.

[0026] Preferably, the first purging in step (1), the second purging in step (2), and the third purging in step (3) are all carried out using inert gas.

[0027] Preferably, the inert gas includes at least one of nitrogen, helium, or argon, and typical but non-limiting combinations include combinations of nitrogen and helium, helium and argon, and nitrogen and argon.

[0028] Preferably, the silicon precursor in step (2) comprises an aminosilane compound.

[0029] The aminosilane compounds include any one or a combination of at least two of BDEAS (bis(diethylamino)silane), DIPAS (diisopropylaminosilane), or BTBAS (bis(tert-butylamino)silane). Typical but non-limiting combinations include combinations of BDEAS and DIPAS, combinations of DIPAS and BTBAS, or combinations of BDEAS, DIPAS, and BTBAS.

[0030] In a second aspect, the present invention provides a method for depositing a doped silicon oxide thin film using a thermal atomic layer deposition process, the method comprising the method for depositing a doped silicon oxide thin film described in the first aspect. Specifically, the method comprises: introducing an oxygen source in step (3) to react with the decomposition products of the doped element precursor and the silicon precursor.

[0031] In this invention, the thermal ALD method is used for oxidation reaction. In step (3), an oxygen source is introduced into the reaction chamber. The oxygen source reacts with the decomposition products of the doped element precursor and the silicon precursor to generate a doped silicon oxide thin film.

[0032] Preferably, the oxygen source has a flow rate of 1.8-2.2 s lpm and an introduction time of 1.8-2.2 s.

[0033] The flow rate of the oxygen source is 1.8-2.2 slpm, for example, it can be 1.8 slpm, 1.9 slpm, 2 slpm, 2.1 slpm or 2.2 slpm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0034] The oxygen source is introduced in 1.8-2.2s, for example, 1.8s, 1.9s, 2s, 2.1s or 2.2s, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0035] Preferably, the oxygen source includes O3.

[0036] Thirdly, the present invention provides a method for depositing a doped silicon oxide thin film using a plasma-enhanced atomic layer deposition process, the method comprising the method for depositing a doped silicon oxide thin film described in the first aspect. Specifically, the method comprises: continuously introducing an oxygen source during steps (1) to (3), and after the second purging in step (2), generating an oxygen source plasma by ionization, which reacts with the decomposition products of the doped element precursor and the silicon precursor.

[0037] The flow rate of the oxygen source is 1.8-2.2 slpm, for example, it can be 1.8 slpm, 1.9 slpm, 2 slpm, 2.1 slpm or 2.2 slpm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0038] In this invention, plasma-enhanced ALD is used for oxidation reaction. Oxygen source is continuously introduced throughout the process. At the same time, after the second purging in step (2), oxygen source plasma is generated by ionization, thereby reacting with the decomposition products of the doped element precursor and the silicon precursor to generate a doped silicon oxide film.

[0039] Preferably, the oxygen source includes at least one of O3, O2, H2O or H2O2, and typical but non-limiting combinations include combinations of O3 and O2, H2O and O2, O3 and H2O, H2O2 and O2, and O3 and H2O2.

[0040] Preferably, the ionization includes radio frequency ignition.

[0041] The discharge power of the radio frequency ignition is 50-500W, and the discharge time is 0.4-0.6s.

[0042] The discharge power of the radio frequency ignition is 50-500W, for example, it can be 50W, 100W, 200W, 300W, 400W or 500W, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0043] The discharge time of the radio frequency ignition is 0.4-0.6s, for example, it can be 0.4s, 0.45s, 0.5s, 0.55s or 0.6s, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0044] Preferably, after generating the doped silicon oxide film of the target thickness, a protective layer is deposited on the surface of the doped silicon oxide film.

[0045] The step of depositing a protective layer can prevent the loss of phosphorus or boron during subsequent annealing.

[0046] The present invention does not impose any special limitations on the steps and processes for depositing the protective layer, and can adopt steps and processes well known to those skilled in the art, which will not be described in detail here.

[0047] Fourthly, the present invention provides a vapor deposition apparatus for depositing doped silicon oxide thin films using a thermal atomic layer deposition process, the vapor deposition apparatus being used to operate a method for depositing doped silicon oxide thin films using the thermal atomic layer deposition process as described in the second aspect, the vapor deposition apparatus comprising a reaction chamber, the reaction chamber comprising:

[0048] The intake assembly is used to input the precursor, oxygen source, and inert gas;

[0049] Base, used to place the base;

[0050] Tail exhaust assembly, used to expel gas from the reaction chamber.

[0051] Fifthly, the present invention provides a vapor deposition apparatus for depositing doped silicon oxide thin films using a plasma-enhanced atomic layer deposition process, the vapor deposition apparatus being used to operate a method for depositing doped silicon oxide thin films using the plasma-enhanced atomic layer deposition process as described in the second aspect, the vapor deposition apparatus comprising a reaction chamber, the reaction chamber comprising:

[0052] The intake assembly is used to input the precursor, oxygen source, and inert gas;

[0053] Plasma generating assembly, used to generate plasma;

[0054] Base, used to place the base;

[0055] Tail exhaust assembly, used to expel gas from the reaction chamber.

[0056] Those skilled in the art will understand that the vapor deposition equipment for depositing doped silicon oxide thin films using plasma-enhanced atomic layer deposition (PEALD) includes an ionization device.

[0057] In this invention, when the plasma-enhanced ALD method is used to deposit doped silicon oxide thin films, the ionization device is turned on.

[0058] Compared with the prior art, the present invention has the following beneficial effects:

[0059] (1) The method for depositing doped silicon oxide thin films provided by the present invention involves thermally decomposing the precursor of the doping element, and then reacting the decomposition products with the silicon precursor and the oxygen source, thereby promoting the deposition of the doped silicon oxide thin film on the substrate. The method first decomposes the precursor of the doping element, and then uses the decomposition products to participate in the reaction and deposit on the substrate surface. Because the decomposition products have high reactivity, it overcomes the problem that phosphorus or boron precursors have low reactivity and are difficult to react in the thermal ALD process. It realizes the deposition of doped silicon oxide thin films by thermal ALD. Moreover, because the thermal ALD process has good conformability, the present invention can also obtain PSG thin films or BSG thin films with high conformability.

[0060] (2) The method for depositing doped silicon oxide thin films provided by the present invention can also deposit doped silicon oxide thin films by plasma-enhanced ALD. For phosphorus precursors that are difficult to react in plasma-enhanced ALD, the method of first decomposing and then using the decomposition products to participate in the reaction and depositing them on the substrate surface broadens the range of precursors for plasma-enhanced ALD. Attached Figure Description

[0061] Figure 1 This is a schematic diagram of the structure of a thermal atomic layer deposition (TAL) apparatus for depositing doped silicon oxide thin films using a thermal atomic layer deposition process provided in a specific embodiment of the present invention.

[0062] Figure 2 This is a schematic diagram of the structure of a plasma-enhanced atomic layer deposition (PEALD) apparatus for depositing doped silicon oxide thin films using a plasma-enhanced atomic layer deposition process provided in a specific embodiment of the present invention.

[0063] The components are: 1. Reaction chamber; 2. Precursor inlet; 3. Oxygen source inlet; 4. Inert gas inlet; 5. Substrate; 6. Heater; 7. Tail exhaust assembly; 8. Radio frequency ionization device.

[0064] Figure 3 This is a thickness distribution diagram of the substrate film in the product prepared in Example 1.

[0065] Figure 4 The images show the infrared and comparative analysis spectra of the substrate film in the product prepared in Example 1.

[0066] Figure 5 This is the XPS phosphorus scan spectrum of the substrate film in the product prepared in Example 1.

[0067] Figure 6 This is a thickness distribution diagram of the substrate film in the product prepared in Example 6.

[0068] Figure 7 This is the XPS phosphorus scan spectrum of the substrate film in the product prepared in Example 6. Detailed Implementation

[0069] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0070] like Figure 1 As shown, some of the following embodiments or comparative examples illustrate the deposition of doped silicon oxide thin films on the substrate surface in a reaction chamber. Taking the thermal ALD process as an example, the schematic diagram of the thermal atomic layer deposition equipment used for depositing doped silicon oxide thin films is shown below. Figure 1 As shown, the vapor deposition apparatus includes a reaction chamber 1, which includes: an inlet assembly for inputting a precursor, an oxygen source, and an inert gas, the inlet assembly including a precursor inlet 2, an oxygen source inlet 3, and an inert gas inlet 4; a base for placing a substrate 5, the non-deposition surface of the substrate 5 being provided with a heater 6; and an exhaust assembly 7 for discharging the gas from the reaction chamber 1.

[0071] like Figure 2 As shown, some of the following embodiments or comparative examples illustrate the deposition of doped silicon oxide thin films on the substrate surface in a reaction chamber. Taking plasma-enhanced ALD (Atomic Layer Deposition) as an example, the schematic diagram of the plasma-enhanced atomic layer deposition equipment used for depositing doped silicon oxide thin films is shown below. Figure 2 As shown, the vapor deposition apparatus includes a reaction chamber 1, which includes: an inlet assembly for inputting a precursor, an oxygen source, and an inert gas, the inlet assembly including a precursor inlet 2, an oxygen source inlet 3, and an inert gas inlet 4; a base for placing a substrate 5, the non-deposition surface of which is provided with a heater 6; and an exhaust assembly 7 for discharging the gas from the reaction chamber 1; the reaction chamber 1 is connected to a radio frequency ionization device 8, which is activated when depositing doped silicon oxide thin films using the plasma-enhanced ALD method.

[0072] The following provides a detailed description of specific embodiments and comparative examples of the thermal atomic layer deposition process.

[0073] Example 1

[0074] This embodiment provides a method for depositing doped silicon oxide thin films using a thermal atomic layer deposition process, the method comprising the following steps:

[0075] (1) The substrate is introduced into the reaction chamber and the reaction temperature is controlled at 330°C; specifically, the substrate temperature is raised to 330°C. The reaction pressure is controlled at 1.5 Torr; specifically, the pressure in the reaction chamber is raised to 1.5 Torr.

[0076] (2) Triethyl phosphate was introduced for 0.5s to thermally decompose it and adsorb it onto the substrate surface. Then, nitrogen was used for the first purging for 0.5s.

[0077] (3) Introduce BDEAS for 0.5s to allow it to adsorb onto the substrate surface, and then purge with nitrogen for 0.5s.

[0078] (4) Introduce O3 at a flow rate of 2slpm for 2s, and then purge with nitrogen for 2s.

[0079] The cycle from step (2) to step (4) is repeated 100 times. In step (4) of this cycle, O3 reacts with the decomposition products of triethyl phosphate and BDEAS.

[0080] Then, steps (3) to (4) are repeated 35 times. In step (4), O3 reacts with BDEAS in an oxidation reaction.

[0081] The thickness pattern of the substrate film (12-inch wafer) of the product obtained in this embodiment is shown in the figure below. Figure 3 As shown, different colors represent different thicknesses, with the unit being Å. Thus, the different color distributions indicate the thickness distribution in different regions. Based on the formula for calculating the in-plane non-uniformity of the thin film, WIWNU(1σ)%=1.46% can be calculated.

[0082] The product film obtained in this embodiment was subjected to infrared detection and compared with the infrared spectra of silicon oxide and phosphorus pentoxide. The infrared spectra and comparison analysis diagrams are shown below. Figure 4 As shown, from Figure 4 It can be seen that the infrared absorption curve of this embodiment contains the Si-O bond absorption peak of the silicon oxide film and the PO bond absorption peak of phosphorus pentoxide, indicating that this embodiment has obtained a P-doped silicon oxide film.

[0083] The product film obtained in this embodiment was subjected to XPS detection, and the phosphorus doping content was found to be 10.91% (atomic percentage). The detection spectrum of P2p is shown below. Figure 5 As shown, from Figure 5 It can be seen that the product film obtained in this embodiment has obvious P peaks, which verifies that the product film obtained in this embodiment is doped with P element.

[0084] Example 2

[0085] This embodiment provides a method for depositing doped silicon oxide thin films using a thermal atomic layer deposition process, the method comprising the following steps:

[0086] (1) The substrate is fed into the reaction chamber and the reaction temperature is controlled at 320°C; specifically, the substrate temperature is raised to 320°C. The reaction pressure is controlled at 2.0 Torr; specifically, the pressure in the reaction chamber is raised to 2.0 Torr.

[0087] (2) Trimethyl phosphite was introduced for 0.4s to thermally decompose it and adsorb it onto the substrate surface. Then, argon gas was used for the first purging for 0.4s.

[0088] (3) Introduce DIPAS for 0.4s to adsorb onto the substrate surface, and then perform a second purging with argon for 0.4s.

[0089] (4) Introduce O3 at a flow rate of 1.8 slpm for 2.2 s, and then perform a third purging with argon for 1.8 s.

[0090] The cycle from step (2) to step (4) is repeated 110 times. In step (4), O3 reacts with the decomposition products of trimethyl phosphite and DIPAS.

[0091] Then, steps (3) to (4) are repeated 35 times. In step (4), O3 reacts with DIPAS in an oxidation reaction.

[0092] Example 3

[0093] This embodiment provides a method for depositing doped silicon oxide thin films using a thermal atomic layer deposition process, the method comprising the following steps:

[0094] (1) The substrate is introduced into the reaction chamber and the reaction temperature is controlled at 340°C; specifically, the substrate temperature is raised to 340°C. The reaction pressure is controlled at 2.5 Torr; specifically, the pressure in the reaction chamber is raised to 2.5 Torr.

[0095] (2) Triethyl borate was introduced for 0.6s to thermally decompose it and adsorb it onto the substrate surface. Then, helium was used for the first purging for 0.6s.

[0096] (3) BTBAS is introduced for 0.6s to adsorb onto the surface of substrate 5, and then helium is used for a second purging for 0.6s.

[0097] (4) Introduce O3 at a flow rate of 2.2 s lpm for 1.8 s, and then use helium for a third purging for 2.2 s.

[0098] The cycle is repeated 90 times from step (2) to step (4). In step (4), O3 reacts with the decomposition products of triethyl borate and BTBAS.

[0099] Then, steps (3) to (4) are repeated 35 times. In step (4), O3 reacts with BTBAS in an oxidation reaction.

[0100] Example 4

[0101] This embodiment provides a method for depositing doped silicon oxide thin films using a thermal atomic layer deposition process. The difference from Embodiment 1 is that steps (2) to (4) are repeated 500 times, and then steps (3) to (4) are repeated 35 times. The rest is the same as in Embodiment 1.

[0102] Example 5

[0103] This embodiment provides a method for depositing doped silicon oxide thin films using a thermal atomic layer deposition process. The difference between this embodiment and Embodiment 1 is that, except for adjusting the flow rate of O3 in step (3) to 1 slpm and keeping the injection time unchanged, the rest is the same as in Embodiment 1.

[0104] Comparative Example 1

[0105] This comparative example provides a method for depositing doped silicon oxide thin films using a thermal atomic layer deposition process. The difference from Example 1 is that the step of introducing O3 is moved to between the introduction of triethyl phosphate and BDEAS, while the rest is the same as in Example 1.

[0106] Steps (2) to (4) specifically include:

[0107] (2) Triethyl phosphate was introduced for 0.5s to thermally decompose it and adsorb it onto the substrate surface. Then, nitrogen was used for the first purging for 0.5s.

[0108] (3) Introduce O3 at a flow rate of 2slpm for 2s, and then purge with nitrogen for 2s.

[0109] (4) Introduce BDEAS for 0.5s to allow it to adsorb onto the substrate surface, and then purge with nitrogen for 0.5s.

[0110] The cycle from step (2) to step (4) is repeated 100 times. In step (3) of this cycle, O3 reacts with the decomposition products of triethyl phosphate.

[0111] Then repeat steps (3) and (4) 35 times.

[0112] Comparative Example 2

[0113] This comparative example provides a method for depositing doped silicon oxide thin films using a thermal atomic layer deposition process. The difference between this method and Example 1 is that an O3 introduction step is added between the introduction of triethyl phosphate and BDEAS. Otherwise, the method is the same as Example 1.

[0114] Steps (2) to (4) are specifically replaced with:

[0115] (2) Triethyl phosphate was introduced for 0.5s to thermally decompose it and adsorb it onto the substrate surface. Then, nitrogen was used for the first purging for 0.5s.

[0116] (3) Introduce O3 at a flow rate of 2slpm for 2s, and then purge with nitrogen for 2s.

[0117] (4) Introduce BDEAS for 0.5s to allow it to adsorb onto the substrate surface, and then purge with nitrogen for 0.5s.

[0118] (5) Introduce O3 at a flow rate of 2slpm for 2s, followed by a third purging with nitrogen for 2s.

[0119] The cycle from step (2) to step (5) is repeated 100 times. In step (3) of this cycle, O3 reacts with the decomposition products of triethyl phosphate.

[0120] Then, steps (4) and (5) are repeated 35 times. In step (5), O3 reacts with BDEAS in an oxidation reaction.

[0121] Comparative Example 3

[0122] This comparative example provides a method for depositing doped silicon oxide thin films using a thermal atomic layer deposition process. The difference from Example 1 is that the reaction temperature is controlled at 190°C. Specifically, the substrate temperature is raised to 190°C (the decomposition temperature of triethyl phosphate is above 200°C). That is, except that triethyl phosphate does not undergo thermal decomposition after being introduced in step (2), everything else is the same as in Example 1.

[0123] Comparative Example 4

[0124] This comparative example provides a method for depositing doped silicon oxide thin films using a thermal atomic layer deposition process. The difference from Example 1 is that step (2) is repeated 500 times, and then steps (3) to (4) are repeated 35 times. The rest are the same as in Example 1.

[0125] The following provides a detailed description of specific embodiments and comparative examples of the plasma-enhanced atomic layer deposition process.

[0126] Example 6

[0127] This embodiment provides a method for depositing doped silicon oxide thin films using a plasma-enhanced atomic layer deposition process, the method comprising the following steps:

[0128] (1) The substrate is introduced into the reaction chamber, and O2 with a flow rate of 1.8 slpm is introduced; the reaction temperature is controlled at 330°C; specifically, the substrate temperature is raised to 330°C. The reaction pressure is controlled at 1.5 Torr; specifically, the pressure in the reaction chamber is raised to 1.5 Torr.

[0129] (2) O2 is continuously introduced at a flow rate of 1.8 slpm; triethyl phosphate is introduced for 0.5 s to thermally decompose it and adsorb it onto the substrate surface, and then nitrogen is used for the first purging for 0.5 s.

[0130] (3) O2 is continuously introduced at a flow rate of 1.8 slpm; BDEAS is introduced for 0.5 s to adsorb onto the substrate surface, and then nitrogen is used for a second purging for 0.5 s.

[0131] (4) O2 is continuously introduced at a flow rate of 1.8 slpm; oxygen plasma is generated by radio frequency ignition. The discharge power of radio frequency ignition is 500W and the discharge time is 0.4s. Then, nitrogen is used for a third purging for 0.18s.

[0132] The cycle from step (2) to step (4) is repeated 110 times. In step (4) of this cycle, oxygen plasma reacts with the decomposition products of triethyl phosphate and BDEAS.

[0133] Then, steps (3) to (4) are repeated 35 times. In step (4), oxygen plasma undergoes an oxidation reaction with BDEAS.

[0134] The thickness pattern of the substrate film (12-inch wafer) of the product obtained in this embodiment is shown in the figure below. Figure 6 As shown, different colors represent different thicknesses, with the unit being Å. The thickness distribution in different regions can be seen from the different color distributions. According to the formula for calculating the in-plane non-uniformity of the thin film, WIWNU(1σ)%=0.53% can be calculated.

[0135] The product film obtained in this embodiment was subjected to XPS detection, and the phosphorus doping content was found to be 12.36% (atomic percentage). The detection spectrum of P2p is shown below. Figure 7 As shown, from Figure 7 It can be seen that the product film obtained in this embodiment has obvious P peaks, which verifies that the product film obtained in this embodiment is doped with P element.

[0136] Example 7

[0137] This embodiment provides a method for depositing doped silicon oxide thin films using a plasma-enhanced atomic layer deposition process, the method comprising the following steps:

[0138] (1) The substrate is introduced into the reaction chamber, and O2 with a flow rate of 2.0 slpm is introduced; the reaction temperature is controlled at 340°C; specifically, the substrate temperature is raised to 340°C. The reaction pressure is controlled at 2.0 Torr; specifically, the pressure in the reaction chamber is raised to 2.0 Torr.

[0139] (2) O2 is continuously introduced at a flow rate of 2.0 slpm; trimethyl phosphite is introduced for 0.6 s to thermally decompose it and adsorb it onto the substrate surface, and then nitrogen is used for the first purging for 0.6 s.

[0140] (3) O2 is continuously introduced at a flow rate of 2.0 slpm; DIPAS is introduced for 0.6 s to adsorb onto the substrate surface, and then nitrogen is used for a second purging for 0.6 s.

[0141] (4) O2 is continuously introduced at a flow rate of 2.0 slpm; oxygen plasma is generated by radio frequency ignition. The discharge power of radio frequency ignition is 450W and the discharge time is 0.5s. Then, nitrogen is used for a third purging for 0.20s.

[0142] The cycle is repeated 80 times from step (2) to step (4). In step (4), oxygen plasma reacts with the decomposition products of trimethyl phosphite and DIPAS.

[0143] Then, steps (3) to (4) are repeated 35 times. In step (4), oxygen plasma undergoes an oxidation reaction with DIPAS.

[0144] Example 8

[0145] This embodiment provides a method for depositing doped silicon oxide thin films using a plasma-enhanced atomic layer deposition process, the method comprising the following steps:

[0146] (1) The substrate is introduced into the reaction chamber, and O2 with a flow rate of 2.2 slpm is introduced; the reaction temperature is controlled at 320°C; specifically, the substrate temperature is raised to 320°C. The reaction pressure is controlled at 2.5 Torr; specifically, the pressure in the reaction chamber is raised to 2.5 Torr.

[0147] (2) O2 is continuously introduced at a flow rate of 2.2 slpm; trimethyl borate is introduced for 0.5 s to thermally decompose it and adsorb it onto the substrate surface, and then nitrogen is used for the first purging for 0.5 s.

[0148] (3) O2 is continuously introduced at a flow rate of 2.2 slpm; BTBAS is introduced for 0.6 s to adsorb onto the substrate surface, and then nitrogen is used for a second purging for 0.6 s.

[0149] (4) O2 is continuously introduced at a flow rate of 2.2 slpm; oxygen plasma is generated by radio frequency ignition with a discharge power of 50W and a discharge time of 0.6s, and then nitrogen is used for a third purging for 0.22s.

[0150] The cycle from step (2) to step (4) is repeated 100 times. In step (4), oxygen plasma reacts with the decomposition products of trimethyl borate and BTBAS.

[0151] Then, steps (3) to (4) are repeated 40 times. In step (4), oxygen plasma reacts with BTBAS in an oxidation reaction.

[0152] Example 9

[0153] This embodiment provides a method for depositing doped silicon oxide thin films using plasma-enhanced atomic layer deposition (PEALD). The difference between this embodiment and Embodiment 6 is that, except for replacing O2 with O3, the rest is the same as in Embodiment 6.

[0154] Comparative Example 5

[0155] This comparative example provides a method for depositing doped silicon oxide thin films using a plasma-enhanced atomic layer deposition process. The difference from Example 6 is that the step of generating oxygen plasma by radio frequency ignition is moved to between the triethyl phosphate and BDEAS, while the rest is the same as Example 6.

[0156] Steps (2) to (4) specifically include:

[0157] (2) O2 is continuously introduced at a flow rate of 1.8 slpm; triethyl phosphate is introduced for 0.5 s to thermally decompose it and adsorb it onto the substrate surface, and then nitrogen is used for the first purging for 0.5 s.

[0158] (3) O2 is continuously introduced at a flow rate of 1.8 slpm; oxygen plasma is generated by radio frequency ignition. The discharge power of radio frequency ignition is 500W and the discharge time is 0.4s. Then, nitrogen is used for a third purging for 0.18s.

[0159] (4) O2 is continuously introduced at a flow rate of 1.8 s lpm; BDEAS is introduced for 0.5 s to adsorb onto the substrate surface, and then nitrogen is used for a second purging for 0.5 s.

[0160] The cycle from step (2) to step (4) is repeated 100 times. In step (3) of this cycle, oxygen plasma reacts with the decomposition products of triethyl phosphate.

[0161] Then repeat steps (3) to (4) 35 times.

[0162] Comparative Example 6

[0163] This comparative example provides a method for depositing doped silicon oxide thin films using a plasma-enhanced atomic layer deposition process. The difference between this example and Example 6 is that, except for the addition of radio frequency ignition to generate oxygen plasma between triethyl phosphate and BDEAS, the method is the same as Example 6.

[0164] Steps (2) to (4) are specifically replaced with:

[0165] (2) O2 is continuously introduced at a flow rate of 1.8 slpm; triethyl phosphate is introduced for 0.5 s to thermally decompose it and adsorb it onto the substrate surface, and then nitrogen is used for the first purging for 0.5 s.

[0166] (3) O2 is continuously introduced at a flow rate of 1.8 slpm; oxygen plasma is generated by radio frequency ignition. The discharge power of radio frequency ignition is 500W and the discharge time is 0.4s. Then, nitrogen is used for a third purging for 0.18s.

[0167] (4) O2 is continuously introduced at a flow rate of 1.8 s lpm; BDEAS is introduced for 0.5 s to adsorb onto the substrate surface, and then nitrogen is used for a second purging for 0.5 s.

[0168] (5) O2 is continuously introduced at a flow rate of 1.8 slpm; oxygen plasma is generated by radio frequency ignition with a discharge power of 500W and a discharge time of 0.4s, and then nitrogen is used for a third purging for 0.18s.

[0169] The cycle from step (2) to step (5) is repeated 100 times. In step (3) of this cycle, oxygen plasma reacts with the decomposition products of triethyl phosphate.

[0170] Then, steps (4) to (5) are repeated 35 times. In step (5), oxygen plasma undergoes an oxidation reaction with BDEAS.

[0171] Comparative Example 7

[0172] This comparative example provides a method for depositing doped silicon oxide thin films using plasma-enhanced atomic layer deposition (PEALD). The difference between this method and Example 6 is that the reaction temperature is controlled at 190°C. Specifically, the substrate temperature is raised to 190°C (the decomposition temperature of triethyl phosphate is above 200°C). That is, except that triethyl phosphate does not undergo thermal decomposition after being introduced in step (2), the rest is the same as in Example 6.

[0173] Test method:

[0174] Thin film thickness measurement: The film thickness was measured using an ellipsometry. Forty-nine uniformly distributed points were taken on the products obtained in the above examples and comparative examples for film thickness measurement, and the average film thickness was calculated to obtain the total thickness of the substrate film. Wherein, THK (thickness of the doped silicon oxide film) = THK (total thickness of the substrate film) - THK (thickness of silicon oxide). The thickness of silicon oxide can be obtained by multiplying its single-cycle growth thickness by the number of cycles, i.e., GPC (growth per cycle) × number of cycles; where silicon oxide is the surface layer, the total thickness of the substrate film minus the thickness of the silicon oxide is the thickness of the doped silicon oxide film.

[0175] In-plane non-uniformity of the thin film: X based on the 49 film thickness data measured at the above 49 points i The formulas for calculating the in-plane non-uniformity %WIWNU(1σ) of the thin film are shown in equations (1) and (2) below:

[0176] Equation (1);

[0177] Equation (2).

[0178] Where σ is the standard deviation of the film thickness test, and X i The film thickness test result at point i. The average value of the film thickness test results for all points is given, and n is the number of test points. In this invention, n is 49.

[0179] It should be noted that, for the same number of cycles, a thicker doped silicon oxide film indicates a better deposition effect; that is, a larger doped silicon oxide film thickness obtained in a single cycle indicates a better deposition effect. Therefore, this invention divides the thickness of the doped silicon oxide film obtained after cycling by the number of cycles to obtain the thickness of the doped silicon oxide film deposited in a single cycle. When the thickness of the doped silicon oxide film deposited in a single cycle is ≥0.5 Å, it is considered a large deposition, indicating that the doped silicon oxide film is easier to form and more dopant elements can combine with Si and O. If it is less than 0.5 Å, it is not considered a large deposition.

[0180] Doped silicon oxide films were deposited using the methods provided in Examples 1-9 and Comparative Examples 1-7. The total thickness of the substrate film, the thickness of the silicon oxide film, the thickness of the doped silicon oxide film, the thickness of the doped silicon oxide film deposited in a single cycle, and whether a large amount of deposition was performed are shown in Table 1.

[0181] Table 1

[0182]

[0183] The following points can be observed from Table 1:

[0184] (1) Analysis of the Example

[0185] As can be seen from Examples 1 to 9, the method for depositing doped silicon oxide thin films provided by the present invention first decomposes the precursor of the doping element, and the resulting decomposition products have high reactivity. These decomposition products can react with the silicon precursor and oxygen source in both thermal atomic layer deposition and plasma-enhanced atomic layer deposition. Therefore, this method can prepare doped silicon oxide thin films using thermal atomic layer deposition and plasma-enhanced atomic layer deposition.

[0186] Furthermore, regarding the deposition process of doped silicon oxide thin films, a single cycle deposition thickness of over 0.540 Å / cycle can achieve the preparation of thick doped silicon oxide thin films. In Examples 1 and 4, the temperature selection is appropriate, and the oxygen source flow rate and inlet time are preferred values. In step (4), the oxidation reaction between O3 and the decomposition products of triethyl phosphate and BDEAS is effective, and the single cycle deposition thickness of the doped silicon oxide thin film is over 2.06 Å / cycle, resulting in the best deposition effect.

[0187] As can be seen from the comparison between Example 1 and Example 4, different doped silicon oxide film thicknesses can be obtained by different number of cycles. Moreover, the thickness of the doped silicon oxide film increases linearly with the increase of the number of cycles. In practical applications, the number of cycles can be adaptively selected according to the product's requirements for the thickness of the doped silicon oxide film.

[0188] A comparison of Examples 1 and 5 shows that Example 5's results indicate that the thickness of the doped silicon oxide film deposited in a single cycle is only 0.540 Å / cycle. Depositing a thick doped silicon oxide film on the substrate requires a lot of time, resulting in relatively low production efficiency. This is because the O3 flow rate in Example 5 is too low, leading to a significant decrease in the oxidation reaction effect compared to Example 1. This indicates that the present invention controls the oxygen source flow rate within a reasonable range, resulting in a better oxidation reaction effect and ultimately a better deposition effect of the doped silicon oxide film.

[0189] As can be seen from the comparison between Example 6 and Example 9, the plasma-enhanced atomic layer deposition process for depositing doped silicon oxide thin films provided by the present invention can deposit a large amount of doped silicon oxide thin films on the substrate surface using different oxygen sources. In practical applications, different oxygen sources can be selected according to actual needs.

[0190] (2) Comparative analysis: For the thermal atomic layer deposition process, it can be seen from the comparison between Example 1 and Comparative Example 1 that the thickness of the doped silicon oxide film deposited in Comparative Example 1 in a single cycle is 0.250 Å / cycle, which is significantly lower than that in Example 1. This is because the O3 introduced after the introduction of triethyl phosphate in Comparative Example 1 will react with the thermal decomposition products of triethyl phosphate, and the reaction products generated by this reaction cannot react with BDEAS, thus the reaction in step (4) cannot continue and a large amount of PSG film cannot be deposited.

[0191] Comparing Example 1 and Comparative Example 2, it can be seen that in Comparative Example 2, O3 is first reacted with the thermal decomposition products of triethyl phosphate in one cycle, and then BDEAS is reacted with O3. The results show that the thickness of the doped silicon oxide film deposited in Comparative Example 2 in a single cycle is 0.210 Å / cycle, which is significantly lower than that in Example 1. This is because the products of the reaction between O3 and the thermal decomposition products of triethyl phosphate in Comparative Example 2 are difficult to form phosphorus-containing substances on the substrate surface, resulting in difficulty in depositing a large amount of doped silicon oxide film.

[0192] Comparing Example 1 and Comparative Example 3, it can be seen that the thickness of the silicon oxide film deposited in Comparative Example 3 in a single cycle is 0.03 Å / cycle, which is almost impossible to achieve. This is because the decomposition temperature of the precursor was not reached in Comparative Example 3, which made it difficult for the precursor to participate in the oxidation reaction in large quantities in step (4), and thus it was impossible to dope the silicon oxide film in large quantities.

[0193] Comparing Example 1 and Comparative Example 4, it can be seen that the thickness of the doped silicon oxide film deposited in Comparative Example 4 is 0.248 Å / cycle, which is slow and cannot achieve a large amount of deposition. This is because in Comparative Example 4, sufficient decomposition products are first accumulated on the substrate surface, but the decomposition products do not react with BDEAS during the 500 cycles, resulting in poor deposition effect. This shows that the present invention first decomposes the dopant precursor and then reacts the decomposition products with the silicon precursor and oxygen source in the same cycle to achieve a large amount of deposition of doped silicon oxide film.

[0194] For plasma-enhanced atomic layer deposition (PEALD) processes,

[0195] As can be seen from the comparison between Example 6 and Comparative Example 5, the thickness of the doped silicon oxide film deposited in Comparative Example 5 in a single cycle is 0.220 Å / cycle, which is significantly lower than that in Example 6. This is because in Comparative Example 5, oxygen plasma is generated by radio frequency ignition between triethyl phosphate and BDEAS. The products generated by the thermal decomposition of triethyl phosphate will react with the oxygen plasma in step (3), and the reaction products generated by this reaction cannot react with BDEAS, so the reaction in step (4) cannot continue and a large amount of PSG film cannot be deposited.

[0196] Comparing Example 6 and Comparative Example 6, it can be seen that in Comparative Example 6, oxygen plasma is first reacted with the thermal decomposition products of triethyl phosphate in one cycle, and then BDEAS is reacted with oxygen plasma. The results show that the thickness of the doped silicon oxide film deposited in Comparative Example 6 in a single cycle is 0.190 Å / cycle, which is significantly lower than that in Example 6. This is because the products of the reaction between oxygen plasma and the thermal decomposition products of triethyl phosphate in Comparative Example 6 are difficult to form phosphorus-containing substances on the substrate surface, resulting in difficulty in depositing a large amount of doped silicon oxide film.

[0197] Comparing Example 6 and Comparative Example 7, it can be seen that the thickness of the silicon oxide film deposited in Comparative Example 7 in a single cycle is 0.02 Å / cycle, which is almost impossible to achieve. This is because the decomposition temperature of the precursor was not reached in Comparative Example 7, which made it difficult for the precursor to participate in the oxidation reaction in large quantities in step (4), and thus it was impossible to dope the silicon oxide film in large quantities.

[0198] In summary, the method for depositing doped silicon oxide thin films provided by this invention thermally decomposes the dopant precursor, and the decomposition products react with the silicon precursor and oxygen source. The decomposition products have high reactivity, thus promoting the deposition of doped silicon oxide thin films on the substrate surface in both thermal ALD and plasma-enhanced processes, achieving large-scale deposition of doped silicon oxide thin films.

[0199] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for depositing doped silicon oxide thin films using a thermal atomic layer deposition process, characterized in that, The method includes the following steps: (1) Introduce the precursor of the doped element, thermally decompose it and adsorb it onto the substrate surface, and then perform the first purging; before introducing the precursor of the doped element in step (1), control the reaction temperature to be no lower than the thermal decomposition temperature of the precursor of the doped element. (2) Introduce the silicon precursor to adsorb onto the substrate surface, and then perform a second purging; (3) Introduce an oxygen source, which reacts with the decomposition products of the doped element precursor and the silicon precursor in an oxidation reaction, followed by a third purging. Repeat steps (1) to (3) until a doped silicon oxide film of the target thickness is formed on the substrate surface.

2. The method for depositing doped silicon oxide thin films using the thermal atomic layer deposition process according to claim 1, characterized in that, The doping element precursor in step (1) includes a phosphorus precursor or a boron precursor; The phosphorus precursor includes phosphine and / or phosphate ester compounds; The boron precursors include boranes and / or borate esters.

3. The method for depositing doped silicon oxide thin films using the thermal atomic layer deposition process according to claim 1, characterized in that, The silicon precursor in step (2) includes aminosilane compounds; The aminosilane compounds include any one or a combination of at least two of BDEAS, DIPAS, or BTBAS.

4. The method for depositing doped silicon oxide thin films using the thermal atomic layer deposition process according to claim 1, characterized in that, The oxygen source has a flow rate of 1.8-2.2 s lpm and an introduction time of 1.8-2.2 s.

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