CN117888080A - Silicon dioxide film and preparation method thereof - Google Patents
Silicon dioxide film and preparation method thereof Download PDFInfo
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- CN117888080A CN117888080A CN202410294017.6A CN202410294017A CN117888080A CN 117888080 A CN117888080 A CN 117888080A CN 202410294017 A CN202410294017 A CN 202410294017A CN 117888080 A CN117888080 A CN 117888080A
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 title claims abstract description 181
- 239000000377 silicon dioxide Substances 0.000 title claims abstract description 89
- 235000012239 silicon dioxide Nutrition 0.000 title claims abstract description 68
- 238000002360 preparation method Methods 0.000 title claims abstract description 31
- 238000006243 chemical reaction Methods 0.000 claims abstract description 84
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 claims abstract description 78
- 238000000034 method Methods 0.000 claims abstract description 42
- 230000007797 corrosion Effects 0.000 claims abstract description 30
- 238000005260 corrosion Methods 0.000 claims abstract description 30
- 230000008569 process Effects 0.000 claims abstract description 28
- 239000000758 substrate Substances 0.000 claims abstract description 17
- 238000000623 plasma-assisted chemical vapour deposition Methods 0.000 claims abstract description 7
- 238000010438 heat treatment Methods 0.000 claims abstract description 4
- 239000003054 catalyst Substances 0.000 claims description 54
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 230000003197 catalytic effect Effects 0.000 claims description 4
- 238000000151 deposition Methods 0.000 abstract description 18
- 239000010408 film Substances 0.000 description 83
- 239000007789 gas Substances 0.000 description 55
- 230000008021 deposition Effects 0.000 description 16
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Inorganic materials [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 15
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 11
- 229910052710 silicon Inorganic materials 0.000 description 11
- 239000010703 silicon Substances 0.000 description 11
- 230000003287 optical effect Effects 0.000 description 5
- 239000011148 porous material Substances 0.000 description 5
- 239000010409 thin film Substances 0.000 description 5
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 239000004065 semiconductor Substances 0.000 description 4
- 229910004298 SiO 2 Inorganic materials 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 238000007796 conventional method Methods 0.000 description 3
- 238000005137 deposition process Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000005979 thermal decomposition reaction Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- NJPPVKZQTLUDBO-UHFFFAOYSA-N novaluron Chemical compound C1=C(Cl)C(OC(F)(F)C(OC(F)(F)F)F)=CC=C1NC(=O)NC(=O)C1=C(F)C=CC=C1F NJPPVKZQTLUDBO-UHFFFAOYSA-N 0.000 description 2
- 229920000620 organic polymer Polymers 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000004886 process control Methods 0.000 description 2
- 239000012495 reaction gas Substances 0.000 description 2
- 229910052814 silicon oxide Inorganic materials 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 229910018557 Si O Inorganic materials 0.000 description 1
- 229910007991 Si-N Inorganic materials 0.000 description 1
- 229910006294 Si—N Inorganic materials 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 229910001413 alkali metal ion Inorganic materials 0.000 description 1
- 230000003667 anti-reflective effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000005693 optoelectronics Effects 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 238000002161 passivation Methods 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
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Abstract
The application discloses a silicon dioxide film and a preparation method thereof. The preparation method adopts a PECVD process and comprises the following steps: s1) placing a substrate in a reaction cavity, heating until the temperature in the reaction cavity is a first temperature preset value, and keeping the first preset time; s2) vacuumizing the reaction cavity to a first pressure preset value, wherein the temperature value in the reaction cavity is the first temperature preset value; s3) introducing TEOS gas into the reaction cavity, wherein the temperature value in the reaction cavity is a second temperature preset value, and the vacuum degree is a second pressure preset value; s4) turning on a radio frequency power supply, wherein the temperature value in the reaction cavity is a third temperature preset value, and the vacuum degree in the reaction cavity is a third pressure preset value, and depositing a silicon dioxide film on the substrate to obtain the required silicon dioxide film. The first, second and third temperature presets are from 0 ℃ to 80 ℃. The silicon dioxide film formed by adopting the TEOS source and combining the process conditions has good corrosion resistance.
Description
Technical Field
The application relates to the technical field of semiconductors, in particular to a silicon dioxide film and a preparation method thereof.
Background
Silicon dioxide (Silicon dioxide, siO) 2 ) The film has the advantages of high hardness, strong resistance to alkali metal ion corrosion, high dielectric strength, good moisture resistance, good corrosion resistance, unique optical characteristics and the like, and is widely applied as a material for preparing semiconductor devices. In silicon-based integrated circuits, silicon dioxide films are used as dielectric layers between metal layers and passivation layers for surface protection; in optoelectronic devices and solar cells, silica thin films are used as waveguide cores, cladding layers and antireflection films with extremely good optical and chemical properties; often used as a sacrificial layer material to support the upper thin film in MEMS devices.
However, the skilled person has found that the above-mentioned silica film is inferior in corrosion resistance.
Disclosure of Invention
The purpose of the application is to disclose a silicon dioxide film and a preparation method thereof. The silicon dioxide film has good corrosion resistance.
In a first aspect, the present application discloses a method of preparing a silica film. The preparation method adopts a PECVD process and comprises the following steps:
s1) placing a substrate in a reaction cavity, heating the reaction cavity until the temperature inside the reaction cavity is a first temperature preset value, and keeping the first preset time;
s2) vacuumizing the reaction cavity to a first pressure preset value, wherein the temperature value in the reaction cavity is the first temperature preset value;
s3) introducing TEOS gas into the reaction cavity, wherein the temperature value in the reaction cavity is a second temperature preset value, and the vacuum degree of the reaction cavity is a second pressure preset value;
s4) turning on a radio frequency power supply, wherein the temperature value in the reaction cavity is a third temperature preset value, the vacuum degree in the reaction cavity is a third pressure preset value, and a silicon dioxide film is deposited on the substrate to obtain a required silicon dioxide film, and the first temperature preset value, the second temperature preset value and the third temperature preset value are respectively 0-80 ℃.
In some embodiments, the first temperature preset value, the second temperature preset value, and the third temperature preset value are equal.
In some embodiments, at least a third pressure preset value of the first pressure preset value, the second pressure preset value, and the third pressure preset value is 40Pa to 200Pa.
In some embodiments, the first pressure preset value, the second pressure preset value, and the third pressure preset value are equal.
In some embodiments, the method of making further comprises: introducing a catalyst into the reaction cavity, wherein the catalyst has a catalytic effect on the TEOS gas, and the volume flow rate of the catalyst is larger than that of the TEOS gas; after the catalyst and TEOS gas are introduced, the vacuum degree in the reaction cavity is the second pressure preset value, and the temperature in the reaction cavity is the second temperature preset value; and after the catalyst and the TEOS gas are kept in the reaction cavity for a third preset time period, executing the step S4.
In some embodiments, a catalyst is introduced first, and then the TEOS gas is introduced, where the duration of introducing the catalyst is at least a second preset duration until the temperature value in the reaction chamber is restored to the first preset temperature value.
In some embodiments, the third preset time period is not less than 5s.
In some embodiments, the catalyst is O 2 The O is 2 The ratio of the volume flow of (2) to the volume flow of the TEOS gas is 10:1 to 40:1.
in some embodiments, the O 2 Is 50sccm-800sccm, the volume flow rate of the TEOS gas is 5sccm-20sccm.
In some embodiments, the second preset time period is not less than 10s.
In some embodiments, the radio frequency power source is a high frequency radio frequency power source with a power of 30w-270w and/or the radio frequency power source is a low frequency power source with a power of 30w-270w.
In some embodiments, where the radio frequency power source comprises a high frequency radio frequency power source and a low frequency radio frequency power source, the difference between the power of the high frequency radio frequency power source and the power of the low frequency radio frequency power source is a, -240 w.ltoreq.a.ltoreq.240 w.
In a second aspect, a silica film is disclosed. The silica film was prepared at a temperature of 10: the corrosion rate of the HF solution of 1 is b, and b is more than or equal to 100nm/min and less than or equal to 200nm/min.
According to the preparation method of the silicon dioxide film and the silicon dioxide film, the TEOS source is adopted as the silicon source, and the process conditions (such as the temperature is 0-80 ℃, the preset pressure value and the preset time period) are combined, so that the silicon dioxide film deposition rate is low, the prepared silicon dioxide particles are small, and finally the film which is small in pore size, less in pore size and more compact is obtained, so that the corrosion resistance is better.
Drawings
FIG. 1 is a schematic view of a deposition apparatus for preparing a silica film;
FIG. 2 is a flow chart illustrating a method of preparing a first silica film according to an embodiment of the present application;
FIG. 3 is a flow chart illustrating a method of preparing a second silica film according to an embodiment of the present application;
FIG. 4 shows the silica film prepared at different temperatures according to the preparation method and the conventional method of the application at 10: a corrosion rate profile in a 1 HF solution;
fig. 5 is a graph of refractive index of silica thin films prepared under different temperature conditions according to the preparation method and the conventional method of the present application.
Detailed Description
Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numbers in different drawings refer to the same or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus consistent with some aspects of the present application as detailed in the accompanying claims.
The terminology used in the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. Unless defined otherwise, technical or scientific terms used herein should be given the ordinary meaning as understood by one of ordinary skill in the art to which this application belongs. The terms "first," "second," and the like in the description and in the claims, are not used for any order, quantity, or importance, but are used for distinguishing between different elements. Likewise, the terms "a" or "an" and the like do not denote a limitation of quantity, but rather denote the presence of at least one. "plurality" or "plurality" means two or more. Unless otherwise indicated, the terms "front," "rear," "lower," and/or "upper" and the like are merely for convenience of description and are not limited to one location or one spatial orientation. The word "comprising" or "comprises", and the like, means that elements or items appearing before "comprising" or "comprising" are encompassed by the element or item recited after "comprising" or "comprising" and equivalents thereof, and that other elements or items are not excluded. The terms "connected" or "connected," and the like, are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any or all possible combinations of one or more of the associated listed items.
The application discloses a preparation method of a silicon dioxide film. Prior to describing the preparation method, the relevant structure of the deposition apparatus 20 used in the preparation method of the present application is described as follows:
referring to fig. 1, the deposition apparatus 20 includes a reaction chamber 21, a thermocouple thermometer 22, a pressure gauge 23, and a catalyst line 24 (e.g., O 2 Piping), a radio frequency power supply 25, a TEOS source piping 26, a showerhead 27, and a substrate pedestal 28. The reaction chamber 21 is a cavity for preparing a silicon dioxide film, also called a PECVD reaction chamber. The thermocouple thermometer 22 is used for measuring the temperature in the reaction chamber 21. The pressure gauge 23 is used to measure the pressure in the reaction chamber 21. The catalyst pipe 24 is used for introducing a catalyst (O) into the reaction chamber 21 2 ) Comprising a catalyst mass meter (O 2 Mass flow meter) gas from the catalyst line 24 passes through a showerhead 27 (e.g., a small orifice of the showerhead 27) into the reaction chamber 21. The skilled artisan will appreciate that the deposition apparatus is not correspondingly provided with catalyst lines 24 and associated components in the event that no catalyst is required. The radio frequency power supply 25 is used for ionizing the reaction gas. The TEOS source conduit 26 is for introducing TEOS gas, including a TEOS mass flow meter, into the reaction chamber 21. Gas from TEOS source line 26 enters reaction chamber 21 through showerhead 27. Of course, the deposition apparatus for preparing the silica thin film of the present application is not limited thereto.
Referring to fig. 2 in combination with fig. 1, a first preparation method of the silicon dioxide film disclosed herein employs a PECVD process, comprising the steps of:
s1) placing a substrate in a reaction cavity 21, heating the reaction cavity 21 until the temperature inside the reaction cavity 21 is a first temperature preset value, and keeping for a first preset time period;
the substrate may be placed on a substrate pedestal 28 within the reaction chamber 21 by directly opening the reaction chamber, or by a robot arm or the like. The thermocouple thermometer 22 measures the temperature inside the reaction chamber 21. The first temperature preset value is in a value range of 0 ℃ to 80 ℃, for example, 0 ℃,5 ℃, 8 ℃,10 ℃, 13 ℃, 15 ℃, 18 ℃, 20 ℃, 25 ℃, 28 ℃, 30 ℃, 33 ℃, 35 ℃, 38 ℃, 40 ℃, 43 ℃, 45 ℃, 48 ℃, 50 ℃, 53 ℃, 55 ℃, 58 ℃, 60 ℃, 62 ℃, 65 ℃, 68 ℃, 70 ℃, 73 ℃, 75 ℃, or 80 ℃. The first preset duration is determined according to the process, and is aimed at ensuring that the temperature in the reaction chamber 21 is uniform, and in this embodiment, the first preset duration is not less than 5s.
S2) vacuumizing the reaction cavity 21 to a first pressure preset value, wherein the temperature value in the reaction cavity 21 is the first temperature preset value;
the first pressure preset value is the process pressure for preparing the silicon dioxide film. In an embodiment of the present application, the first pressure preset value is 40pa to 200pa.
S3) introducing TEOS gas into the reaction cavity 21, wherein the temperature value in the reaction cavity 21 is a second temperature preset value, and the vacuum degree of the reaction cavity 21 is a second pressure preset value;
in this step, the TEOS gas is introduced into the reaction chamber 21 through the TEOS source line 26, and the mass flow meter in the TEOS source line 26 can strictly control the flow rate of the TEOS gas entering the reaction chamber 21. The reaction chamber 21 is evacuated, requiring the vacuum gauge 23 to reach a second pressure preset value. The second temperature preset value can also be 0-80 ℃. Within this range, the second temperature preset value may not be equal to the first preset temperature value. The second pressure preset value may be equal to the first pressure preset value, such as 40Pa-200Pa.
S4) turning on a radio frequency power supply, wherein the temperature value in the reaction cavity 21 is a third temperature preset value, and the vacuum degree in the reaction cavity is a third pressure preset value, and depositing a silicon dioxide film on the substrate to obtain the required silicon dioxide film.
In this step, the RF power source 25 is turned on to ionize the gases in the reaction chamber 21 (TEOS gas in this embodiment, TEOS and O in other embodiments 2 A gas mixture of components). The third temperature preset value can be 0-80 ℃ as well. The third pressure preset value is based on the film uniformity and the total amount of TEOS gas (i.e., silicon source) subsequently introduced (of course, in the embodiment shown in fig. 3, and also based on the total amount of TEOS gas and O 2 Total amount of (c) is determined. If the third pressure is presetToo low, ionization may be difficult or even unsuccessful during the subsequent entire deposition process; if the third pressure preset is too high, the uniformity of the finally deposited silicon dioxide film is very poor. Therefore, in the embodiment of the present application, the value range of the third pressure preset value is 40Pa-200Pa, based on the consideration of easy ionization and good uniformity. Of course, the third pressure preset value may be other values. And maintaining the third pressure preset value and the third temperature preset value for three preset time periods according to the thickness of the deposited silicon dioxide film.
The preparation method can also comprise the following steps: s5) the mass flow meters on TEOS source lines 26 are all set to zero, stopping the reaction gas (in this embodiment, the gas is TEOS gas, in other embodiments, stopping O 2 And TEOS gas) is introduced into the reaction chamber 21, the temperature value of the thermocouple thermometer 22 is maintained unchanged (i.e., the temperature in the reaction chamber 21 is unchanged), the vacuum degree of the reaction chamber is set to zero, the reaction chamber 21 is vacuumized, and the fifth preset time period is maintained; s6: after the deposition of the low temperature silicon dioxide film, the substrate is transferred out of the reaction chamber 21.
For the preparation method, a TEOS source is adopted as a silicon source, and the process steps and/or conditions (such as the temperature is 0-80 ℃, the preset pressure values and the preset time period) are adopted, so that the deposition rate of the silicon dioxide film is low, the prepared silicon dioxide particles are small, and the film which is small in pore space, few and compact is finally obtained, so that the corrosion resistance is better. Whereas conventional methods for preparing silicon dioxide films use SiH as the silicon source 4 And oxygen source N 2 O, the silicon dioxide film formed contains a large amount of Si-H bonds which are easily oxidized in air, resulting in deterioration of corrosion resistance, which may deteriorate the overall device performance.
Further, in the above embodiment, the first, second, and third temperature preset values of the present application are 0 ℃ to 80 ℃. Thus, the method of preparing a silicon dioxide film by combining this temperature value relationship with the aforementioned TEOS source can be understood as a method of preparing a silicon dioxide film at a low temperature. The preparation method not only prepares the silicon dioxide film meeting the requirements, but also has the following two advantages: a) The process temperature is greatly reduced, the energy consumption is reduced, and the cost is saved; b) The requirements of integrating optical paths and circuits or a Damascus process on a through silicon via (Through Silicon Via, TSV) and a semiconductor substrate can be met, the application range of a silicon dioxide film is enlarged, and a choice is provided for preparing a temperature sensitive device or a polymer photoelectric device with special requirements on deposition temperature; therefore, the temperature is reduced, and the performance (corrosion resistance, uniformity, stress and the like) of the silicon dioxide film can be guaranteed not to be reduced, so that the application scene of the silicon dioxide film is greatly expanded, and the following description of fig. 5 can be seen. Whereas conventional PECVD is usually carried out at a temperature above 350 ℃, the reactive gas SiH 4 And N 2 And generating plasma under the action of a radio frequency electric field to generate the silicon dioxide film. Such a silicon dioxide film has a narrow application range, for example, cannot be applied to the through silicon via (Through Silicon Via, TSV) technology because of the insulating dielectric layer SiO in the TSV technology 2 It is desirable to deposit at lower temperatures because high temperatures may lead to failure of the chip. For example, the optical path and the circuit are integrated on the semiconductor substrate, organic polymer materials are usually used, and the temperature which can be born by the organic polymers is relatively low and needs to be lower than 150 ℃, so the preparation method of the low-temperature silicon dioxide film is of great significance for realizing the optical path and the circuit. As another example, in a 45nm dual damascene process, low temperature SiO 2 The thin film is used as a hard mask layer and if the deposition temperature is too high it may result in a change of the properties of the underlying anti-reflective film layer, which in turn results in failure of the whole process.
In the preparation method, the first temperature preset value, the second temperature preset value and the third temperature preset value are equal, so that the process control is convenient, and the performance of the prepared silicon dioxide film is stable because the process conditions are equal. The equality may be a certain number in the range of 0 ℃ to 80 ℃.
In the above embodiment, at least the third pressure preset value is 40Pa to 200Pa, that is, the first pressure preset value, the second pressure preset value, and the third pressure preset value are respectively 40Pa to 200Pa, or only the third pressure preset value may be 40Pa to 200Pa.
In the preparation method, at least the third pressure preset value is 40Pa-200Pa, so that on one hand, ionization is easy to occur in the subsequent ionization step, and on the other hand, the uniformity of the silicon dioxide film is good. Because if the aforementioned pressure values are too low, ionization may hardly occur during the entire subsequent deposition process, even if the ionization is unsuccessful; if the foregoing pressure values are too high, the uniformity of the finally deposited silicon dioxide film may be very poor.
In the above embodiment, the first pressure preset value, the second pressure preset value and the third pressure preset value are equal, so that not only is the process control convenient, but also the performance of the prepared silicon dioxide film is stable because the process conditions are equal. The equality may be a certain value in the range of 40Pa-200Pa, or a certain value outside the range of 40Pa-200Pa.
Of course, in the above preparation method, the following two conditions are adopted: a) At least a third pressure preset value among the first pressure preset value, the second pressure preset value and the third pressure preset value is 40Pa-200Pa; b) The first pressure preset value, the second pressure preset value and the third pressure preset value are equal; a and b are satisfied, or only one of them is satisfied.
In the above embodiment, the rf power supply 25 is a high-frequency rf power supply, and the power is 30w-270w. In other embodiments, the RF power source is a low frequency RF power source with a power of 30w-270w. In some embodiments, the RF power source is a high frequency RF power source and the low frequency power source is a RF power source, and the power is 30-270w. In still other embodiments, the difference between the power of the high frequency RF power source and the power of the low frequency RF power source is a, -240 w.ltoreq.a.ltoreq.240 w. When a=0, the power of the high-frequency radio frequency power supply and the power of the low-frequency radio frequency power supply are equal, and of course, in addition to being equal, the following two cases are included: 1) The power of the high-frequency radio frequency power supply is larger than that of the low-frequency radio frequency power supply; 2) The power of the high frequency radio frequency power supply is less than the power of the low frequency radio frequency power supply. The inventors have found that the power of the high frequency rf power source and/or the power of the low frequency rf power source affects the stress, voids, etc. (corrosion resistance) of the silica film. The power of the radio frequency power supply is 30w-270w, the stress of the silicon dioxide film can be kept in a smaller range, the stress is smaller, the silicon dioxide film can be prevented from being broken, and the like, in addition, when the power is in the range or the power difference is in the range, the pores of the silicon dioxide film are small and less, the compactness is better, and the corrosion resistance can be improved. When the rf power source is a high-frequency rf power source or a low-frequency rf power source, the deposition apparatus 20 is simpler, has fewer variable factors, and has good process stability, and finally ensures stable performance of the silicon dioxide film, such as good corrosion resistance and good stress stability.
Referring to fig. 3 in combination with fig. 1, a second method of making a silica film is also disclosed. The second preparation method is compared with the first preparation method, and the second preparation method further comprises the following steps: step S23: a catalyst is introduced into the reaction chamber 21. The catalyst has a catalytic effect on the TEOS gas, and the volume flow rate of the catalyst is larger than that of the TEOS gas. And after the catalyst and the TEOS gas are kept in the reaction cavity for a third preset time period, executing the step S4.
In step S23, how to feed the catalyst is not limited, for example, in the aforementioned deposition apparatus, the catalyst passes through the catalyst pipe 24 and then passes through the small holes in the shower head 27 to enter the reaction chamber 21. After the catalyst and the TEOS gas are introduced, the vacuum degree in the reaction chamber 21 is a second pressure preset value, and the temperature in the reaction chamber 21 is the second temperature preset value.
In the second preparation method, the effect of maintaining the third preset time period is to fully mix the catalyst and TEOS gas, so that the uniformity and compactness of the silicon dioxide film are improved (the formed silicon dioxide film has small and less pores, is more compact and has good corrosion resistance). In the embodiment of the application, the third preset time period is not less than 5s, so that the uniformity and the corrosion resistance of the silicon dioxide film are better. In addition, the volume flow rate of the catalyst is larger than that of TEOS gas, so that the catalyst and TEOS are well mixed, and the uniformity and corrosion resistance of the silicon dioxide film are improved.
According to the second preparation method of the silicon dioxide film, after the catalyst is introduced, the catalyst can enhance the activity of TEOS gas and shorten the process time; furthermore, the flow rate of the catalyst is greater than the volume flow rate of the TEOS gas, and the third preset time period is maintained, so that the uniformity and corrosion resistance of the silicon dioxide film are good.
The order of introducing the catalyst and TEOS gas is not limited based on the effect of the foregoing catalyst. In an embodiment of the present application, a catalyst is introduced first, and then the TEOS gas is introduced, where a duration of introducing the catalyst is at least a second preset duration, until a temperature value in the reaction chamber is restored to the first temperature preset value.
In the above embodiment, since the flow rate of the catalyst is greater than the flow rate of the TEOS gas, the temperature and pressure in the reaction chamber 21 are not easily caused to fluctuate after the catalyst is introduced, for example, when the catalyst is introduced first, a part of heat on the substrate is taken away, so that the temperature of the substrate is reduced, the temperature of the substrate is raised to the first temperature preset value along with the increase of the time of introducing the catalyst, and the flow rate of the TEOS gas is smaller than the flow rate of the catalyst, so that the temperature and pressure in the reaction chamber 21 are not easily caused to fluctuate. If the TEOS gas is introduced first and then the catalyst is introduced, the flow rate of the catalyst is larger than that of the TEOS gas, which causes fluctuation of temperature and pressure in the reaction chamber 21, and is unfavorable for stabilizing the temperature and pressure in the reaction chamber 21.
In some embodiments, the catalyst is O 2 The O is 2 The ratio of the volume flow of (2) to the volume flow of the TEOS gas is 10:1 to 40:1.
O 2 the method has two functions for preparing the silicon dioxide film by TEOS gas, namely, the TEOS gas is fully and uniformly mixed in the reaction cavity, and the second method has a catalytic effect on thermal decomposition of the TEOS gas to generate SiO 2 And organic matter. Thermal decomposition of TEOS to form SiO 2 The chemical equation of (2) is:
for O 2 The ratio of the volume flow of (2) to the volume flow of TEOS was 10:1 to 40: within the range of 1, a sufficient amount of oxygen can be used as a catalyst to perform thermal decomposition reaction mainly due to insufficient chemical activity of TEOS, and a uniform film with good corrosion resistance is deposited. If O 2 Is not large enough, O 2 The ratio of TEOS gas to O is smaller 2 May not be completely uniformly mixed, resulting in poor uniformity of the final film and poor corrosion resistance; if O 2 Is large enough to have O 2 The ratio of TEOS gas to TEOS gas is larger, so that the introduced TEOS gas is possibly less, the deposition rate is too low, and in addition, the catalyst is O 2 The silicon dioxide film does not contain Si-H bond, is not easy to oxidize and has good corrosion resistance. To sum up, O 2 The ratio of the volume flow of (2) to the volume flow of TEOS gas is 10:1 to 40:1.
In some embodiments, the O 2 The volume flow rate of the TEOS gas is 50sccm-800sccm, and the volume flow rate of the TEOS gas is 5sccm-20sccm.
As set forth above, the deposition rate can be ensured, and uniformity and corrosion resistance of the silicon oxide film can also be improved, because too low a volumetric flow rate of TEOS gas results in a very slow deposition rate, and if too large a volumetric flow rate of TEOS gas results in poor deposition uniformity and corrosion resistance.
In some embodiments, the second preset time period is not less than 10s. Thus, since the duration of the catalyst is not less than 10 seconds, the vacuum degree can be kept stable because the catalyst (O 2 ) The flow is larger than TEOS flow, and the large-flow gas is introducedThe vacuum degree can be influenced to a certain extent when the reaction chamber is filled, so that a certain recovery time is given to the reaction chamber, the vacuum degree is ensured to be stable, and if the time is too short, the reaction chamber does not have enough time to recover the vacuum degree, and the vacuum degree is unstable.
Preparation of low temperature silica film from TEOS source a series of comparative experiments were performed in accordance with the following conditions to illustrate the advantages of the preparation method of the silica film of the present application.
Condition a: first pressure preset value 40Pa, O 2 200sccm flow, 10sccm TEOS flow, 100w power of the RF power supply, and 30 ℃.
Condition B: first pressure preset value 40Pa, O 2 200sccm flow, 10sccm TEOS flow, 100w power of the RF power supply, and 70 ℃.
To prepare SiO in accordance with embodiments of the present invention and conventional PECVD 2 Process comparison using the apparatus described in fig. 2, 5% sih was used 4 /N 2 (5% SiH) 4 Gas at N 2 Mixed gas of (b) as silicon source to replace TEOS, N 2 O is used as oxygen source to replace O 2 A series of comparative tests were performed under the following conditions.
Condition C: first pressure preset value 130Pa, N 2 Flow rate of O460 sccm,5% SiH 4 /N 2 The flow rate is 250sccm, the power of the radio frequency power supply is 50w, and the process temperature is 200 ℃.
Condition D: first pressure preset value 130Pa, N 2 Flow rate of O460 sccm,5% SiH 4 /N 2 The flow rate is 250sccm, the power of the radio frequency power supply is 50w, and the process temperature is 300 ℃.
Condition E: first pressure preset value 130Pa, N 2 Flow rate of O460 sccm,5% SiH 4 /N 2 The flow rate is 250sccm, the power of the radio frequency power supply is 50w, and the process temperature is 350 ℃.
Condition F: first pressure preset value 130Pa, N 2 Flow rate of O460 sccm,5% SiH 4 /N 2 The flow rate is 250sccm, the power of the radio frequency power supply is 50w, and the process temperature is 400 ℃.
As can be seen from FIG. 4, the HF corrosion resistance of the low temperature silicon dioxide film prepared from TEOS sourceIs significantly better than conventional SiH 4 Silicon dioxide film prepared by the process, even SiO prepared by TEOS source process under the condition of 30 DEG C 2 A film, which is at 10: the etching rate in the 1 HF solution is only 139.8nm/min, which is far lower than that of the conventional SiH 4 SiO prepared by the process under 400 DEG C 2 Corrosion rate of the film against HF solution. Therefore, the silica film is excellent in corrosion resistance.
As can be seen from FIG. 5, siO can be generally used 2 The compactness is reflected by the refractive index of the film, and the higher the refractive index is under the same condition, the better the compactness is. Comparison found that conventional SiH was used 4 SiO prepared by the process 2 The higher refractive index of the film, already exceeding 1.49 at 350 ℃, is due to the 5% SiH used in the comparative test 4 /N 2 Wherein 95% is N 2 Si-N bonds are generated during the deposition process, instead of 100% Si-O bonds, the presence of which eventually leads to an increase in its refractive index. It is well known that SiO is prepared by thermal oxidation process 2 The refractive index is approximately 1.46, and the refractive index of the low-temperature silicon dioxide film prepared by the TEOS source is larger than 1.46. In summary, compared with the refractive index, the compactness of the silicon dioxide film is not different from or greater than that of the silicon dioxide film prepared by the high-temperature process, and thus the silicon dioxide film prepared by the thermal oxidation process has good corrosion resistance.
In summary, the performance (such as compactness, of course, the skilled person will understand that the performance also includes uniformity and stress) of the silicon dioxide film prepared by the method is not reduced, and the resistance to hydrofluoric acid solution is better.
In addition, it should be noted that: although with the catalyst (O) 2 ) Embodiments of (2) and 5% SiH 4 /N 2 (5% SiH) 4 Gas at N 2 Mixed gas of (b) as a silicon source, N 2 Embodiments in which O is used as the oxygen source are used as a comparison, however, one of skill will appreciate that the silica preparation methods of the present application also allow for dioxygen without the use of a catalystThe silicon oxide film performance (such as compactness, of course, the skilled person will understand that the performance also includes uniformity and stress) is not reduced, and the hydrofluoric acid solution corrosion resistance is better.
In another aspect, embodiments of the present application also disclose a silica film. The HF corrosion rate of the silicon dioxide film is b, and b is more than or equal to 100nm/min and less than or equal to 200nm/min. For example, 100nm/min, 103nm/min, 105nm/min, 107nm/min, 109nm/min, 110nm/min, 113nm/min, 115nm/min, 118nm/min, 120nm/min, 123nm/min, 125nm/min, 129nm/min, 133nm/min, 135nm/min, 140nm/min, 145nm/min, 148nm/min, 150nm/min, 153nm/min, 155nm/min, 158nm/min, 160nm/min, 165nm/min, 168nm/min, 170nm/min, 173nm/min, 175nm/min, 178nm/min, 180nm/min, 183nm/min, 185nm/min, 188nm/min, 190nm/min, 193nm/min, 195nm/min, 198nm/min, or 200nm/min.
The foregoing description of the preferred embodiments of the present application is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, alternatives, and alternatives falling within the spirit and scope of the invention.
Claims (10)
1. The preparation method of the silicon dioxide film is characterized by adopting a PECVD process and comprises the following steps:
s1) placing a substrate in a reaction cavity, heating the reaction cavity until the temperature inside the reaction cavity is a first temperature preset value, and keeping the first preset time;
s2) vacuumizing the reaction cavity to a first pressure preset value, wherein the temperature value in the reaction cavity is the first temperature preset value;
s3) introducing TEOS gas into the reaction cavity, wherein the temperature value in the reaction cavity is a second temperature preset value, and the vacuum degree of the reaction cavity is a second pressure preset value;
s4) turning on a radio frequency power supply, wherein the temperature value in the reaction cavity is a third temperature preset value, the vacuum degree in the reaction cavity is a third pressure preset value, and a silicon dioxide film is deposited on the substrate to obtain a required silicon dioxide film, and the first temperature preset value, the second temperature preset value and the third temperature preset value are 0-80 ℃.
2. The method of claim 1, wherein the first temperature preset value, the second temperature preset value, and the third temperature preset value are equal.
3. The method of claim 1, wherein at least a third pressure preset value of the first pressure preset value, the second pressure preset value, and the third pressure preset value is 40Pa to 200Pa;
and/or the first pressure preset value, the second pressure preset value and the third pressure preset value are equal.
4. The method for producing a silica film according to claim 1, characterized in that the method for producing further comprises: introducing a catalyst into the reaction cavity, wherein the catalyst has a catalytic effect on the TEOS gas, and the volume flow rate of the catalyst is larger than that of the TEOS gas;
after the catalyst and TEOS gas are introduced, the vacuum degree in the reaction cavity is the second pressure preset value, and the temperature in the reaction cavity is the second temperature preset value; and after the catalyst and the TEOS gas are kept in the reaction cavity for a third preset time period, executing the step S4.
5. The method according to claim 4, wherein a catalyst is introduced first, and then the TEOS gas is introduced, wherein the duration of introducing the catalyst is at least a second preset duration until the temperature value in the reaction chamber is restored to the first preset temperature value;
and/or, the third preset time period is not less than 5s.
6. According to claim 5The preparation method of the silicon dioxide film is characterized in that the catalyst is O 2 The O is 2 The ratio of the volume flow of (2) to the volume flow of the TEOS gas is 10:1 to 40:1.
7. the method for producing a silica film according to claim 6, wherein the O 2 The volume flow rate of the TEOS gas is 50sccm-800sccm, and the volume flow rate of the TEOS gas is 5sccm-20sccm;
and/or the second preset time period is not less than 10s.
8. The method of claim 1, wherein the rf power source is a high frequency rf power source with a power of 30w to 270w and/or the rf power source is a low frequency power source with a power of 30w to 270w.
9. The method according to claim 8, wherein in the case where the radio frequency power source includes a high frequency radio frequency power source and a low frequency radio frequency power source, a difference between the power of the high frequency radio frequency power source and the power of the low frequency radio frequency power source is a, -240 w.ltoreq.a.ltoreq.240 w.
10. A silica film, characterized in that the silica film is formed at a ratio of 10: the corrosion rate of the HF solution of 1 is b, and b is more than or equal to 100nm/min and less than or equal to 200nm/min.
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