High-quality phosphorosilicate glass and preparation method thereof

Abstract

The invention discloses high-quality phosphorosilicate glass and a preparation method thereof, and relates to the technical field of semiconductor chip processing. A preparation method of high-quality phosphorosilicate glass comprises the following steps: carrying out thermal oxidation treatment on a silicon wafer, and depositing a silicon dioxide film on the surface of the silicon wafer; depositing a phosphorus-containing polycrystalline silicon film on the silicon wafer on which the silicon dioxide film is deposited; and performing high-temperature diffusion on the silicon wafer, taking out the silicon wafer, and removing the polycrystalline silicon on the surface to obtain the phosphorosilicate glass. The problem of low breakdown of phosphorosilicate glass is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor chip processing, and in particular to high-quality phosphosilicate glass and a preparation method thereof. Background Art

[0002] Semiconductor integrated circuits and power devices are both derivatives and extensions of electronic components. In nearly all semiconductor devices, silicon dioxide serves as a key film layer, forming the core structure of the device. Its primary functions include device protection, device isolation, underlying hard mask, and sacrificial oxygen.

[0003] When used for device protection and isolation, silicon dioxide films rely primarily on its excellent insulation and chemical stability. On the device surface, they act as a stable protective layer, preventing particles and contaminants from entering the device, potentially leading to device failure or performance degradation. Inside the device, they act as an insulating barrier, preventing short circuits between internal components.

[0004] With the development of integrated circuit manufacturing technology and the continuous breakthroughs of Moore's Law, higher requirements have been placed on device protection and device isolation. Traditional silicon dioxide can no longer meet the needs of devices in some structures, so doped silicon dioxide has emerged. By introducing certain impurities, the properties of silicon dioxide are changed to meet specific functional requirements. Phosphorus silicate glass (PSG) is the addition of phosphorus into silicon dioxide. Phosphorus replaces the position of silicon atoms in the silicon dioxide network structure, forming impurities for the network, and changing the structure and properties of the network. When it replaces the position of silicon atoms, pentavalent phosphorus is added to the silicon dioxide network in the form of P2O5. There will be an extra oxygen atom for every two P-O tetrahedrons. This extra oxygen atom promotes non-bridging oxygen in silicon dioxide, thereby making the network structure loose, so that it has the ability to flow like a liquid to a certain extent under high temperature conditions, greatly improving the coverage and pore filling ability of the film layer; in addition, the valence electron on the phosphorus atom that is not bound by a covalent bond can effectively trap Na + , K + Positive ions protect devices from the influence of mobile ions, avoiding potential electrical characteristics and functional failures.

[0005] Based on these two properties, phosphosilicate glass (PSG) has become a high-quality film widely used in semiconductor devices. Its fluidity at high temperatures provides excellent pore-filling capabilities, achieving good surface coverage and enhancing device protection and isolation. Mobile ionic contaminants are adsorbed by phosphorus, preventing them from entering the wafer surface. This reaction, known as "guttering," also significantly improves device stability.

[0006] However, since traditional phosphosilicate glass is prepared by CVD, which is generated through reactions of silane, phosphine, nitrous oxide, etc., the silicon dioxide film layer is relatively loose, and the breakdown voltage of the film is much lower than that of silicon dioxide grown by thermal oxidation. It often has a low breakdown phenomenon, which is not conducive to device protection. Summary of the Invention

[0007] The technical problem to be solved by the present invention is that the phosphosilicate glass prepared by the existing method has a low breakdown phenomenon, which is not conducive to the protection of the device. The purpose is to provide a high-quality phosphosilicate glass and a preparation method thereof to solve the problem of low breakdown of phosphosilicate glass.

[0008] The present invention is achieved through the following technical solutions: A method for preparing high-quality phosphosilicate glass comprises the following steps: The silicon wafer is subjected to thermal oxidation treatment to deposit a silicon dioxide film on the surface of the silicon wafer; Depositing a phosphorus-containing polysilicon film on a silicon wafer on which a silicon dioxide film is deposited; The silicon wafer is diffused at high temperature, and then the surface polysilicon is taken out and removed to obtain phosphosilicate glass.

[0009] As a possible design, the thermal oxidation treatment of the silicon wafer is specifically to perform the thermal oxidation treatment on the silicon wafer at 900-1150° C. in an atmosphere of a mixture of oxygen, hydrogen and nitrogen.

[0010] As a possible design, the thickness of the silicon dioxide film is 0.1 to 1 μm.

[0011] As a possible design, the above-mentioned deposition of phosphorus-containing polysilicon film is specifically carried out at 600-760° C., an atmosphere of a mixture of SiH 4 , PH 3 , O 2 and N 2 O, and a furnace pressure of 150-250 mTorr.

[0012] As a possible design, the thickness of the polysilicon is 4000 Å to 10000 Å.

[0013] As a possible design, the high-temperature diffusion of the silicon wafer is specifically carried out at 1100-1200° C. in an atmosphere of N 2 and a low-oxygen mixed gas for 120-220 minutes.

[0014] As a possible design, the removal of the surface polysilicon is specifically performed by dry etching or wet etching.

[0015] As a possible design, before the silicon wafer is subjected to thermal oxidation treatment, it is cleaned with cleaning reagent 1 and cleaning reagent 2 in sequence; Cleaning with cleaning reagent 1 specifically involves cleaning the silicon wafer with cleaning reagent 1 at 110-130°C for 4-6 minutes, and then rinsing with water; The cleaning with the cleaning reagent 2 specifically involves cleaning the silicon wafer with the cleaning reagent 2 for 1 to 3 minutes, and then rinsing with water.

[0016] As a possible design, the phosphosilicate glass is further cleaned with cleaning reagent 3 and cleaning reagent 4 in sequence; Phosphorus silicate glass is cleaned with cleaning agent 3. Specifically, cleaning is performed with cleaning agent 3 at 35-45°C for 4-6 minutes, and then rinsed with water. The phosphosilicate glass is cleaned with cleaning reagent 4, specifically, cleaning with cleaning reagent 4 at 30-40° C. for 3-5 minutes, and then rinsing with water.

[0017] In a second aspect, the present invention provides a high-quality phosphosilicate glass, which is prepared by the above-mentioned preparation method.

[0018] Compared with the prior art, the present invention has the following advantages and beneficial effects: The present invention first grows a silicon dioxide film through thermal oxidation; then deposits a layer of phosphorus-containing polysilicon on the surface of the silicon dioxide; then, through thermal diffusion in a high-temperature furnace tube, the phosphorus in the polysilicon diffuses into the underlying silicon dioxide; the diffused phosphorus exists in the form of PO in the silicon dioxide, and together with Si-O in the silicon dioxide, forms phosphosilicate glass. In this way, phosphorus atoms are diffused into the silicon dioxide using doped polysilicon as a medium, replacing the phosphorus-containing silicon dioxide prepared by the traditional CVD method, thereby obtaining phosphosilicate glass and improving the film properties. The prepared film is dense and clean, and has improved pressure resistance; finally, the surface polysilicon is removed, leaving a layer of high-quality phosphosilicate glass. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the examples. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be considered as limiting the scope. A person of ordinary skill in the art can also derive other relevant drawings based on these drawings without inventive effort. In the drawings: Figure 1 is a flow chart of the present invention; Figure 2 This is a test chart of phosphorus content in the phosphosilicate glass according to Example 2 of the present invention; Figure 3 This is a test chart of the phosphorus content of the phosphosilicate glass of Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with Examples and accompanying drawings. The illustrative embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention. In the examples, if specific conditions are not specified, the conditions according to conventional conditions or manufacturer's recommendations are used. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0021] Because existing phosphosilicate glass can withstand a very low maximum voltage under an electric field, it is easily damaged and provides poor device protection. This can lead to dangerous situations such as short circuits and arcing, posing a threat to the safety of the device and the entire circuit system. Therefore, to improve the reliability and safety of devices, the present invention provides a method for preparing high-quality phosphosilicate glass, effectively increasing the breakdown voltage of the glass and thereby enhancing its device protection.

[0022] A method for preparing high-quality phosphosilicate glass, referring to Figure 1 , including the following steps: S0. Clean the silicon wafer with cleaning reagent 1 and cleaning reagent 2 in sequence.

[0023] In some embodiments of the present invention, the cleaning with the cleaning reagent 1 specifically involves cleaning the silicon wafer with the cleaning reagent 1 at 110-130° C. for 4-6 minutes, and then rinsing with water.

[0024] Preferably, the cleaning reagent 1 comprises sulfuric acid and hydrogen peroxide. The volume ratio of the sulfuric acid to the hydrogen peroxide is 3.8 to 4.2:1, and preferably, the volume ratio of the sulfuric acid to the hydrogen peroxide is 4:1.

[0025] In some embodiments of the present invention, the cleaning with the cleaning reagent 2 specifically involves cleaning the silicon wafer with the cleaning reagent 2 for 1 to 3 minutes, and then rinsing with water.

[0026] Preferably, the cleaning reagent 2 comprises hydrofluoric acid and water, wherein the volume ratio of the hydrofluoric acid to water is 1:45-55, preferably 1:50.

[0027] S1. Thermally oxidize the silicon wafer to deposit a silicon dioxide film on the surface of the silicon wafer.

[0028] In some embodiments of the present invention, the thermal oxidation treatment of the silicon wafer is performed at 900-1150°C in an atmosphere of a mixture of oxygen, hydrogen, and nitrogen. For example, the volume ratio of oxygen to hydrogen is 1:1.7. The specific process involves oxygen and hydrogen reacting to form water, which reacts with silicon to form silicon dioxide. Nitrogen acts as an auxiliary gas and does not participate in the oxidation.

[0029] In some embodiments of the present invention, the silicon dioxide film has a thickness of 0.1 to 1 μm. The thickness can be any value within the range of 0.1 to 1 μm, including but not limited to 0.5 μm, 0.3 μm, 0.8 μm, 0.95 μm, or other values. Preferably, the silicon dioxide film has a thickness of 0.3 to 0.8 μm.

[0030] S2. Depositing a phosphorus-containing polysilicon film on the silicon wafer on which the silicon dioxide film is deposited.

[0031] In some embodiments of the present invention, the above-mentioned deposition of the phosphorus-containing polysilicon film is specifically carried out at 600-760°C, in an atmosphere of a mixture of SiH4, PH3, O2 and N2O, and a furnace pressure of 150-250 mTorr. Under these pressure conditions, the film density, adhesion and purity are better. The temperature for depositing the phosphorus-containing polysilicon film is preferably 630-730°C, but can be any value within this range. The furnace pressure can be any value within 150-250 mTorr, including but not limited to 160 mTorr, 170 mTorr, 185 mTorr, 200 mTorr, 215 mTorr or other arbitrary values, and more preferably 180-220 mTorr. For example, in an atmosphere with a volume ratio of SiH4, PH3 and N2 of 10:1:20, SiH4 decomposes to produce silicon, PH3 decomposes to produce phosphorus, and N2 is a diluent gas to improve the uniformity of the reaction.

[0032] In some embodiments of the present invention, the polysilicon thickness is 4000A to 10000A. Preferably, the polysilicon thickness can be any value within the range of 4000A to 10000A, including but not limited to 5000A, 5500A, 6000A, 7000A, 9000A or any other value. More preferably, the polysilicon thickness is 6000A to 9000A. If the polysilicon thickness is too thin, the total amount of phosphorus impurities will be too low, and the subsequent phosphorus diffusion concentration will be too low; if the polysilicon thickness is too large, it will result in a waste of cost.

[0033] S3. Diffusion of the silicon wafer at high temperature, then taking out and removing the surface polysilicon to obtain phosphosilicate glass.

[0034] In some embodiments of the present invention, the high-temperature diffusion of the silicon wafer is specifically carried out at 1100-1200° C. in an N 2 atmosphere and a low-oxygen mixed gas for 120-220 minutes. For example, the volume ratio of N 2 to O 2 is 50:1.

[0035] In some embodiments of the present invention, the removal of the surface polysilicon is performed by dry etching or wet etching.

[0036] Preferably, the surface polysilicon is removed by dry etching in a mixed etching gas of Cl2 and HBr at a power of 250-350W and a chamber pressure of 5-15 mTorr. The surface polysilicon film can be removed by dry etching.

[0037] S4. Clean the phosphosilicate glass with cleaning agent 3 and cleaning agent 4 in sequence. It should be noted that cleaning agent 3 mainly removes particles and contamination on the surface; cleaning agent 4 mainly removes possible metal ions.

[0038] In some embodiments of the present invention, the phosphosilicate glass is cleaned with the cleaning reagent 3 by cleaning with the cleaning reagent 3 at 35-45° C. for 4-6 minutes, and then rinsed with water.

[0039] Preferably, the cleaning reagent 3 comprises ammonia water, hydrogen peroxide and water. Preferably, the volume ratio of ammonia water, hydrogen peroxide and water is (4-6):1:20, more preferably 5:1:20.

[0040] In some embodiments of the present invention, the phosphosilicate glass is cleaned with the cleaning agent 4 by cleaning with the cleaning agent 4 at 30-40° C. for 3-5 minutes and then rinsed with water.

[0041] Preferably, the cleaning reagent 3 comprises hydrochloric acid, hydrogen peroxide and water. Preferably, the volume ratio of the hydrochloric acid, hydrogen peroxide and water is (3-8):2:20, more preferably 5:2:20.

[0042] The present invention also provides high-quality phosphosilicate glass prepared by the above method.

[0043] Example 1 A method for preparing high-quality phosphosilicate glass comprises the following steps: The silicon wafer was cleaned with cleaning reagent 1 and cleaning reagent 2 in sequence: the silicon wafer was cleaned with cleaning reagent 1 (sulfuric acid and hydrogen peroxide volume ratio of 3.8:1) at 110℃ for 6 minutes, and then rinsed with water, and repeated three times; the silicon wafer was cleaned with cleaning reagent 2 (hydrofluoric acid and water volume ratio of 1:45) for 1 minute, and then rinsed with water, and repeated three times; The silicon wafer was thermally oxidized at 900°C in an atmosphere of a mixture of oxygen, hydrogen, and nitrogen to obtain a silicon dioxide film with a thickness of 0.3 μm. A phosphorus-containing polysilicon film with a thickness of 4000 Å was deposited on a silicon wafer having a silicon dioxide film at 600°C in an atmosphere of a mixture of SiH4, PH3, O2 and N2O at a furnace pressure of 150 mTorr. The silicon wafer was diffused for 120 minutes at 1100°C in an N2 atmosphere with a low-oxygen mixed gas. The wafer was then taken out and dry-etched in a Cl2 and HBr mixed etching gas at 250W power and a chamber pressure of 5mTorr to remove the surface polysilicon and obtain phosphosilicate glass. Clean the phosphosilicate glass with cleaning reagent 3 and cleaning reagent 4 in sequence: clean with cleaning reagent 3 (ammonia, hydrogen peroxide and water in a volume ratio of 4:1:20) at 35-45°C for 4 minutes, then rinse with water, and repeat 3 times; clean with cleaning reagent 4 (hydrochloric acid, hydrogen peroxide and water in a volume ratio of 3:2:20) at 30-40°C for 3 minutes, then rinse with water, and repeat 3 times.

[0044] Example 2 A method for preparing high-quality phosphosilicate glass comprises the following steps: The silicon wafer was cleaned with cleaning reagent 1 and cleaning reagent 2 in sequence: the silicon wafer was cleaned with cleaning reagent 1 (sulfuric acid and hydrogen peroxide in a volume ratio of 4:1) at 120°C for 5 minutes, then rinsed with water, and repeated four times; the silicon wafer was cleaned with cleaning reagent 2 (hydrofluoric acid and water in a volume ratio of 1:50) for 2 minutes, then rinsed with water, and repeated four times; The silicon wafer was thermally oxidized at 1030°C in an atmosphere of a mixture of oxygen, hydrogen and nitrogen to obtain a silicon dioxide film with a thickness of 0.5 μm. A phosphorus-containing polysilicon film with a thickness of 7000 Å was deposited on a silicon wafer having a silicon dioxide film deposited thereon at 680°C in an atmosphere of a mixture of SiH4, PH3, O2 and N2O at a furnace pressure of 200 mTorr. The silicon wafer was diffused for 170 minutes at 1130°C in an N2, low-oxygen atmosphere. The wafer was then removed and dry-etched in a Cl2 and HBr mixed etching gas at 290W power and 9mTorr chamber pressure to remove the surface polysilicon and obtain phosphosilicate glass. Clean the phosphosilicate glass with cleaning reagent 3 and cleaning reagent 4 in sequence: use cleaning reagent 3 (ammonia, hydrogen peroxide and water in a volume ratio of 5:1:20) to clean at 40°C for 50 minutes, then rinse with water, and repeat 5 times; use cleaning reagent 4 (hydrochloric acid, hydrogen peroxide and water in a volume ratio of 5:2:20) to clean at 35°C for 4 minutes, then rinse with water, and repeat 5 times.

[0045] Example 3 A method for preparing high-quality phosphosilicate glass comprises the following steps: The silicon wafer was cleaned with cleaning reagent 1 and cleaning reagent 2 in sequence: the silicon wafer was cleaned with cleaning reagent 1 (sulfuric acid and hydrogen peroxide in a volume ratio of 4.2:1) at 130°C for 6 minutes, then rinsed with water, and repeated 5 times; the silicon wafer was cleaned with cleaning reagent 2 (hydrofluoric acid and water in a volume ratio of 1:55) for 3 minutes, then rinsed with water, and repeated 5 times; The silicon wafer was thermally oxidized at 1150°C in an atmosphere of a mixture of oxygen, hydrogen, and nitrogen to obtain a silicon dioxide film with a thickness of 0.9 μm. A phosphorus-containing polysilicon film with a thickness of 9000 Å was deposited on a silicon wafer having a silicon dioxide film deposited thereon at 760°C in an atmosphere of a mixture of SiH4, PH3, O2 and N2O at a furnace pressure of 250 mTorr. The silicon wafer was diffused for 220 minutes at 1200°C in an N2, low-oxygen atmosphere. The wafer was then taken out and dry-etched in a Cl2 and HBr mixed etching gas at 350W power and 15mTorr chamber pressure to remove the surface polysilicon and obtain phosphosilicate glass. Clean the phosphosilicate glass with cleaning reagent 3 and cleaning reagent 4 in sequence: clean with cleaning reagent 3 (ammonia, hydrogen peroxide and water in a volume ratio of 6:1:20) at 45°C for 6 minutes, then rinse with water, and repeat 4 times; clean with cleaning reagent 4 (hydrochloric acid, hydrogen peroxide and water in a volume ratio of 8:2:20) at 40°C for 5 minutes, then rinse with water, and repeat 4 times.

[0046] Comparative Example 1 In this comparative example, the PSG thin film was prepared by conventional CVD method.

[0047] A method for preparing high-quality phosphosilicate glass comprises the following steps: The silicon wafer was cleaned with cleaning reagent 1 and cleaning reagent 2 in sequence: the silicon wafer was cleaned with cleaning reagent 3 (ammonia, hydrogen peroxide, and water in a volume ratio of 5:1:20) at 30°C for 5 minutes, then rinsed with water, and repeated four times; the silicon wafer was cleaned with cleaning reagent 2 (hydrofluoric acid and water in a volume ratio of 1:50) for 2 minutes, then rinsed with water, and repeated four times; The silicon wafer was subjected to thermal oxidation treatment at 850°C in an atmosphere of a mixed gas of SiH4, PH3, O2, and N2O and a furnace pressure of 300 mTorr to obtain phosphorus-silicate glass deposited on the surface. Clean the phosphosilicate glass with cleaning reagent 3 and cleaning reagent 4 in sequence: use cleaning reagent 3 (ammonia, hydrogen peroxide and water in a volume ratio of 5:1:20) to clean at 40°C for 50 minutes, then rinse with water, and repeat 5 times; use cleaning reagent 4 (hydrochloric acid, hydrogen peroxide and water in a volume ratio of 5:2:20) to clean at 35°C for 4 minutes, then rinse with water, and repeat 5 times.

[0048] Comparative Example 2 This comparative example is basically the same as Example 2, except that: the surface of the silicon wafer after thermal oxidation treatment is thermally diffused using P paper, and then a phosphorus-containing polysilicon film is deposited.

[0049] A method for preparing high-quality phosphosilicate glass comprises the following steps: The silicon wafer was cleaned with cleaning reagent 1 and cleaning reagent 2 in sequence: the silicon wafer was cleaned with cleaning reagent 1 (sulfuric acid and hydrogen peroxide in a volume ratio of 4:1) at 120°C for 5 minutes, then rinsed with water, and repeated four times; the silicon wafer was cleaned with cleaning reagent 2 (hydrofluoric acid and water in a volume ratio of 1:50) for 2 minutes, then rinsed with water, and repeated four times; The silicon wafer is subjected to thermal oxidation treatment at 1030°C in an atmosphere of a mixture of oxygen, hydrogen and nitrogen to obtain a silicon dioxide film; The silicon wafer with the deposited silicon dioxide film was thermally diffused using a P-paper source, specifically at 1130°C in an N2 and low-oxygen mixed gas atmosphere for 170 minutes. The phosphorus-containing polysilicon film was formed on a heat-diffused silicon wafer at 680°C in an atmosphere of a mixture of SiH4, PH3, O2 and N2O at a furnace pressure of 200mTorr; The silicon wafer was dry-etched in a mixed etching gas of Cl2 and HBr at a power of 290W and a chamber pressure of 9mTorr to remove the surface polysilicon and obtain phosphosilicate glass. Clean the phosphosilicate glass with cleaning reagent 3 and cleaning reagent 4 in sequence: use cleaning reagent 3 (ammonia, hydrogen peroxide and water in a volume ratio of 5:1:20) to clean at 40°C for 50 minutes, then rinse with water, and repeat 5 times; use cleaning reagent 4 (hydrochloric acid, hydrogen peroxide and water in a volume ratio of 5:2:20) to clean at 35°C for 4 minutes, then rinse with water, and repeat 5 times.

[0050] Comparative Example 3 This comparative example is basically the same as comparative example 2, except that thermal diffusion is performed after the phosphorus-containing polysilicon film is deposited.

[0051] A method for preparing high-quality phosphosilicate glass comprises the following steps: The silicon wafer was cleaned with cleaning reagent 1 and cleaning reagent 2 in sequence: the silicon wafer was cleaned with cleaning reagent 1 (sulfuric acid and hydrogen peroxide in a volume ratio of 4:1) at 120°C for 5 minutes, then rinsed with water, and repeated four times; the silicon wafer was cleaned with cleaning reagent 2 (hydrofluoric acid and water in a volume ratio of 1:50) for 2 minutes, then rinsed with water, and repeated four times; The silicon wafer is subjected to thermal oxidation treatment at 1030°C in an atmosphere of a mixture of oxygen, hydrogen and nitrogen to obtain a silicon dioxide film; The silicon wafer with the deposited silicon dioxide film was thermally diffused using a P-paper source, specifically at 1130°C in an N2 and low-oxygen mixed gas atmosphere for 170 minutes. The heat-diffused silicon wafer was deposited with a phosphorus-containing polysilicon film at 680°C in an atmosphere of a mixture of SiH4, PH3, O2 and N2O at a furnace pressure of 200 mTorr. The phosphorus-containing polysilicon film was diffused at 1130°C in a mixed gas atmosphere of N2 and low oxygen for 170 min. The silicon wafer was dry-etched in a mixed etching gas of Cl2 and HBr at a power of 290W and a chamber pressure of 9mTorr to remove the surface polysilicon and obtain phosphosilicate glass. Clean the phosphosilicate glass with cleaning reagent 3 and cleaning reagent 4 in sequence: use cleaning reagent 3 (ammonia, hydrogen peroxide and water in a volume ratio of 5:1:20) to clean at 40°C for 50 minutes, then rinse with water, and repeat 5 times; use cleaning reagent 4 (hydrochloric acid, hydrogen peroxide and water in a volume ratio of 5:2:20) to clean at 35°C for 4 minutes, then rinse with water, and repeat 5 times.

[0052] Comparative Example 4 This comparative example is basically the same as Example 2, except that when depositing the phosphorus-containing polysilicon film, the furnace tube pressure is 300 mTorr.

[0053] Comparative Example 5 This comparative example is basically the same as Example 2, except that when depositing the phosphorus-containing polysilicon film, the diffusion time is 250 minutes.

[0054] Comparative Example 6 This comparative example is basically the same as Example 2, except that the diffusion temperature is 1000° C. when depositing the phosphorus-containing polysilicon film.

[0055] Comparative Example 7 This comparative example is basically the same as comparative example 2, except that when depositing the phosphorus-containing polysilicon film, the diffusion time is 250 minutes.

[0056] Experimental example (1) The phosphorus content of the phosphosilicate glass of Example 2 and Comparative Example 2 was tested. The results are as follows: Figure 2-3 shown.

[0057] analyze Figure 2-3 The phosphorus content in the silicon dioxide of the phosphosilicate glass prepared by the conventional CVD method (Comparative Example 1) and the present method (Example 2) can be adjusted to be essentially equivalent, with a typical value of 1.1E20, which improves the breakdown capability. Due to the effect of phosphorus, both have effective mobile ion blocking and absorption capabilities, as well as good pore filling ability.

[0058] (2) Conventional phosphosilicate glass, silicon dioxide thermally oxidized using the method of Example 2 alone, the phosphosilicate glass of Example 2, and the phosphosilicate glasses of Comparative Examples 1-7 were tested for breakdown voltage (surface metal electrodes were made on the phosphosilicate glass, and then a probe was used to contact the metal to test the breakdown voltage). The results are shown in Table 1.

[0059] Table 1

[0060] Referring to Table 1, a comparison between Example 2 and Comparative Example 1 shows that the breakdown voltage capability of the phosphosilicate glass of the present invention is comparable to that of thermally oxidized silicon dioxide and is much higher than that of conventional CVD phosphosilicate glass. This is because the phosphosilicate glass obtained by thermal oxidation has a dense film quality, which increases the phosphorus content and impurity gettering ability, thereby improving the breakdown capability. Comparison of Example 2 with Comparative Example 2 shows that the breakdown voltage capability of the phosphosilicate glass of the present invention is comparable to that of thermally oxidized silica, and is much higher than that of the phosphosilicate glass obtained by diffusion of P-paper. This is because the presence of more particles and dirt in the diffusion of P-paper affects the quality of the phosphosilicate glass and reduces the breakdown capability. Comparison of Example 2 with Comparative Example 3 shows that the breakdown voltage capability of the phosphosilicate glass of the present invention is comparable to that of thermally oxidized silica, and is much higher than that of the phosphosilicate glass obtained by diffusion of P paper. This is because the P paper diffusion contains more particles and contamination, which reduces the breakdown capability. From the comparison of Comparative Example 1 with Comparative Example 2 and Comparative Example 3, it can be seen that the breakdown ability of the phosphosilicate glass obtained by the conventional CVD process and the P-paper diffusion process is much lower than that of the method of the embodiment of the present invention due to the influence of density or particles / contamination.

[0061] From the comparison between Example 2 and Comparative Example 4, it can be seen that when the furnace tube pressure is greater than 250 mTorr, the growth process window of P-containing polysilicon is larger. As long as the polysilicon grows normally, stable phosphosilicate glass can be formed in the subsequent P diffusion process, thereby obtaining a higher breakdown capability. From the comparison between Example 2 and Comparative Example 5, it can be seen that when the diffusion time is greater than 220 min, the breakdown voltage will not be further increased because the diffusion of P in SiO2 is already stable, but a higher breakdown voltage can be obtained; From the comparison between Example 2 and Comparative Example 6, it can be seen that when the diffusion temperature is lower than 1100°C, a slight concentration gradient distribution appears when P diffuses in SiO2. Since P itself is in excess, the effect is very slight, resulting in a very slight decrease in the gettering ability and a slightly lower breakdown voltage.

[0062] From the comparison between Comparative Example 7 and Comparative Example 2, it can be seen that the phosphosilicate glass obtained by diffusion of P paper has a large number of particles and dirt in the diffusion process, which affects the quality of the phosphosilicate glass and thus reduces the breakdown ability.

[0063] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing high-quality phosphosilicate glass, characterized in that: The steps include: The silicon wafer is subjected to thermal oxidation treatment to deposit a silicon dioxide film on the surface of the silicon wafer; Depositing a phosphorus-containing polysilicon film on a silicon wafer on which a silicon dioxide film is deposited; The silicon wafer is diffused at high temperature, and then the surface polysilicon is taken out and removed to obtain phosphosilicate glass.

2. The method for preparing high-quality phosphosilicate glass according to claim 1, characterized in that: The thermal oxidation treatment of the silicon wafer is specifically performed by subjecting the silicon wafer to thermal oxidation treatment at 900-1150° C. in an atmosphere of a mixed gas of oxygen, hydrogen and nitrogen.

3. The method for preparing high-quality phosphosilicate glass according to claim 1, characterized in that: The thickness of the silicon dioxide film is 0.1-1 μm.

4. The method for preparing high-quality phosphosilicate glass according to claim 1, wherein: The phosphorus-containing polysilicon film is deposited under the conditions of 600-760° C., an atmosphere of a mixed gas of SiH 4 , PH 3 , O 2 and N 2 O, and a furnace pressure of 150-250 mTorr.

5. The method for preparing high-quality phosphosilicate glass according to claim 1, wherein: The thickness of the polysilicon is 4000Å to 10000Å.

6. The method for preparing high-quality phosphosilicate glass according to claim 1, characterized in that: The high-temperature diffusion of the silicon wafer is specifically carried out at 1100-1200° C. in an atmosphere of N 2 and a low-oxygen mixed gas for 120-220 minutes.

7. The method for preparing high-quality phosphosilicate glass according to claim 1, characterized in that: The removal of the surface polysilicon is specifically carried out by dry etching or wet etching.

8. The method for preparing high-quality phosphosilicate glass according to claim 1, characterized in that: Before the silicon wafer is subjected to thermal oxidation treatment, it is cleaned with cleaning reagent 1 and cleaning reagent 2 in sequence; Cleaning with cleaning reagent 1 specifically involves cleaning the silicon wafer with cleaning reagent 1 at 110-130°C for 4-6 minutes, and then rinsing with water; The cleaning with the cleaning reagent 2 specifically involves cleaning the silicon wafer with the cleaning reagent 2 for 1 to 3 minutes, and then rinsing with water.

9. The method for preparing high-quality phosphosilicate glass according to claim 1, wherein: The phosphosilicate glass is also cleaned sequentially with cleaning reagent 3 and cleaning reagent 4; Phosphorus silicate glass is cleaned with cleaning agent 3. Specifically, cleaning is performed with cleaning agent 3 at 35-45°C for 4-6 minutes, and then rinsed with water. The phosphosilicate glass is cleaned with cleaning reagent 4, specifically, cleaning with cleaning reagent 4 at 30-40° C. for 3-5 minutes, and then rinsing with water.

10. A high-quality phosphosilicate glass, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 9.

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