CN117352383B - Method for preparing groove - Google Patents
Method for preparing groove Download PDFInfo
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- CN117352383B CN117352383B CN202311658648.3A CN202311658648A CN117352383B CN 117352383 B CN117352383 B CN 117352383B CN 202311658648 A CN202311658648 A CN 202311658648A CN 117352383 B CN117352383 B CN 117352383B
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- oxide layer
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- silicon oxide
- aluminum oxide
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- 238000000034 method Methods 0.000 title claims abstract description 112
- 238000005530 etching Methods 0.000 claims abstract description 95
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 63
- 229910052814 silicon oxide Inorganic materials 0.000 claims abstract description 60
- 239000000758 substrate Substances 0.000 claims abstract description 49
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims abstract description 46
- 229920002120 photoresistant polymer Polymers 0.000 claims abstract description 41
- 230000008439 repair process Effects 0.000 claims abstract description 39
- 230000000149 penetrating effect Effects 0.000 claims abstract description 9
- 239000007789 gas Substances 0.000 claims description 50
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims description 17
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 17
- 229910052731 fluorine Inorganic materials 0.000 claims description 17
- 239000011737 fluorine Substances 0.000 claims description 17
- 238000004519 manufacturing process Methods 0.000 claims description 15
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 14
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 14
- 239000000463 material Substances 0.000 claims description 14
- 229910052760 oxygen Inorganic materials 0.000 claims description 14
- 239000001301 oxygen Substances 0.000 claims description 14
- 229910052710 silicon Inorganic materials 0.000 claims description 14
- 239000010703 silicon Substances 0.000 claims description 14
- 238000005137 deposition process Methods 0.000 claims description 11
- 229910052717 sulfur Inorganic materials 0.000 claims description 6
- 239000011593 sulfur Substances 0.000 claims description 6
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 4
- 229910052799 carbon Inorganic materials 0.000 claims description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims 1
- 230000009286 beneficial effect Effects 0.000 abstract description 3
- 238000002360 preparation method Methods 0.000 abstract description 3
- 230000000694 effects Effects 0.000 description 4
- 210000001015 abdomen Anatomy 0.000 description 2
- 238000005452 bending Methods 0.000 description 2
- 239000000945 filler Substances 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- JBRZTFJDHDCESZ-UHFFFAOYSA-N AsGa Chemical compound [As]#[Ga] JBRZTFJDHDCESZ-UHFFFAOYSA-N 0.000 description 1
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 1
- LEVVHYCKPQWKOP-UHFFFAOYSA-N [Si].[Ge] Chemical compound [Si].[Ge] LEVVHYCKPQWKOP-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- -1 aluminum ions Chemical class 0.000 description 1
- 238000004380 ashing Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000000708 deep reactive-ion etching Methods 0.000 description 1
- 238000001312 dry etching Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000011368 organic material Substances 0.000 description 1
- 238000000059 patterning Methods 0.000 description 1
- 238000001020 plasma etching Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
- H01L21/306—Chemical or electrical treatment, e.g. electrolytic etching
- H01L21/3065—Plasma etching; Reactive-ion etching
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
- H01L21/306—Chemical or electrical treatment, e.g. electrolytic etching
- H01L21/308—Chemical or electrical treatment, e.g. electrolytic etching using masks
- H01L21/3081—Chemical or electrical treatment, e.g. electrolytic etching using masks characterised by their composition, e.g. multilayer masks, materials
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
- H01L21/306—Chemical or electrical treatment, e.g. electrolytic etching
- H01L21/308—Chemical or electrical treatment, e.g. electrolytic etching using masks
- H01L21/3083—Chemical or electrical treatment, e.g. electrolytic etching using masks characterised by their size, orientation, disposition, behaviour, shape, in horizontal or vertical plane
- H01L21/3085—Chemical or electrical treatment, e.g. electrolytic etching using masks characterised by their size, orientation, disposition, behaviour, shape, in horizontal or vertical plane characterised by their behaviour during the process, e.g. soluble masks, redeposited masks
Abstract
The invention provides a preparation method of a groove, which comprises the following steps: providing a substrate, wherein an aluminum oxide layer, a silicon oxide layer and a graphical photoresist layer are sequentially formed on the substrate; performing a first etching process, sequentially etching the silicon oxide layer and the aluminum oxide layer by taking the patterned photoresist layer as a mask to form an opening penetrating through the silicon oxide layer and the aluminum oxide layer, wherein the side wall of the opening is provided with a plurality of protrusions, and the patterned photoresist layer is synchronously etched and removed when the opening is formed; performing a first repair process to remove protrusions of the sidewalls of the opening to smooth the sidewalls of the opening; executing a second etching process, etching the substrate downwards along the opening by taking the silicon oxide layer and the aluminum oxide layer as masks so as to form a groove in the substrate, and synchronously etching and removing the silicon oxide layer when the groove is formed; performing a second repair process to make the side wall of the trench vertical; and removing the aluminum oxide layer. The invention improves the verticality of the side wall of the groove and is beneficial to obtaining the groove with accurate characteristic dimension.
Description
Technical Field
The invention relates to the technical field of semiconductors, in particular to a method for preparing a groove.
Background
In the process of deep reactive ion etching the substrate, the patterned photoresist layer and the patterned silicon oxide layer are used as masks, and then dry etching of the substrate is performed, so that a trench with high depth-to-width ratio is formed. In the trench etching process, the film thickness of the photoresist layer serving as a mask is required to be large, and meanwhile, the selectivity requirement on the mask is very high, and the silicon oxide layer of one of the masks cannot provide a high selectivity ratio, so that the cost economy is poor. The side wall perpendicularity of the groove is easy to be poor due to long-time etching, the surface roughness is large, the loading effect is brought, and the depth of the formed groove is uneven. During the process, the bending phenomenon (big belly), the damage of the side wall of the groove, the ripple effect and the like easily occur in the groove due to a large amount of plasma bombardment, and the subsequent process and the component yield are affected. For example, fig. 1 is a schematic cross-sectional view of a trench formed in the prior art, referring to fig. 1, since the silicon oxide layer 30 of one of the masks cannot provide a high selectivity, after the silicon oxide layer 30 is etched to form the opening 50, the sidewall of the opening 50 is inclined, and a better opening profile cannot be provided to transfer into the substrate 10, so that a bending phenomenon (large belly) is easily generated in the trench 60.
Disclosure of Invention
The invention aims to provide a preparation method of a groove, which improves the verticality of the side wall of the groove and is beneficial to obtaining the groove with more accurate characteristic dimension.
In order to achieve the above object, the present invention provides a method for manufacturing a trench, including:
providing a substrate, wherein an aluminum oxide layer, a silicon oxide layer and a graphical photoresist layer are sequentially formed on the substrate;
a first etching process is carried out, the patterned photoresist layer is used as a mask to etch the silicon oxide layer and the aluminum oxide layer in sequence, so that an opening penetrating through the silicon oxide layer and the aluminum oxide layer is formed, a plurality of protrusions are arranged on the side wall of the opening, and the patterned photoresist layer is synchronously etched and removed when the opening is formed;
performing a first repair process to remove protrusions of the side walls of the openings so as to smooth the side walls of the openings;
performing a second etching process, namely etching the substrate downwards along the opening by taking the silicon oxide layer and the aluminum oxide layer as masks so as to form a groove in the substrate, and synchronously etching and removing the silicon oxide layer when the groove is formed;
performing a second repair process to make the side wall of the groove vertical; the method comprises the steps of,
and removing the aluminum oxide layer.
Optionally, the step of forming an opening through the silicon oxide layer and the aluminum oxide layer includes:
executing the first etching process, etching the silicon oxide layer to form the opening by taking the patterned photoresist layer as a mask, and synchronously etching to remove part of the patterned photoresist layer with the thickness;
and continuing to execute the first etching process, etching the aluminum oxide layer downwards along the opening so that the opening extends to the surface of the substrate to form an opening penetrating through the silicon oxide layer and the aluminum oxide layer, and synchronously etching to remove the patterned photoresist layer with the residual thickness.
Optionally, the process gas of the first etching process includes a gas containing fluorine and sulfur.
Optionally, the process gas of the first repair process includes a gas containing silicon and fluorine and oxygen.
Optionally, when the silicon oxide layer and the aluminum oxide layer are used as masks to etch the substrate downwards along the opening, the silicon oxide layer is gradually etched and lost until the silicon oxide layer is removed.
Optionally, the second etching process includes a deposition process and an etching process, and the deposition process and the etching process are cyclically and alternately performed.
Optionally, the process gas of the deposition process includes a fluorine-and-carbon-containing gas, and the process gas of the etching process includes a fluorine-and-sulfur-containing gas.
Optionally, the process gas of the second repair process includes a gas containing silicon and fluorine and oxygen.
Optionally, the depth-to-width ratio of the trench is greater than 20:1.
Optionally, the step of removing the alumina layer includes:
forming a filling material layer in the groove to fill the groove;
etching to remove the alumina layer; the method comprises the steps of,
and removing the filling material layer.
In the method for preparing the groove, a substrate is provided, and an alumina layer, a silicon oxide layer and a graphical photoresist layer are sequentially formed on the substrate; performing a first etching process, sequentially etching the silicon oxide layer and the aluminum oxide layer by taking the patterned photoresist layer as a mask to form an opening penetrating through the silicon oxide layer and the aluminum oxide layer, wherein the side wall of the opening is provided with a plurality of protrusions, and the patterned photoresist layer is synchronously etched and removed when the opening is formed; performing a first repair process to remove protrusions of the sidewalls of the opening to smooth the sidewalls of the opening; executing a second etching process, etching the substrate downwards along the opening by taking the silicon oxide layer and the aluminum oxide layer as masks so as to form a groove in the substrate, and synchronously etching and removing the silicon oxide layer when the groove is formed; performing a second repair process to make the side wall of the trench vertical; and removing the aluminum oxide layer. In the invention, the unexpected technical effect is that the side wall of the opening can be repaired by using the first repairing process to provide better opening outline to be transferred into the substrate, and the substrate is etched by using the alumina layer as a mask to provide higher etching selection ratio, so that the side wall of the groove formed by etching is more vertical; and repairing the side wall of the groove by using a second repairing process to further improve the verticality of the side wall of the groove.
Drawings
Fig. 1 is a schematic cross-sectional view of a trench formed in the prior art.
Fig. 2 is a flowchart of a method for manufacturing a trench according to an embodiment of the present invention.
Fig. 3 is a schematic cross-sectional view of a substrate provided in a method for manufacturing a trench according to an embodiment of the invention.
Fig. 4 is a schematic cross-sectional view of a trench according to an embodiment of the present invention after a first etching process is performed to etch a silicon oxide layer.
Fig. 5 is a schematic cross-sectional view of a trench according to an embodiment of the present invention after etching an alumina layer by performing a first etching process.
Fig. 6 is a schematic cross-sectional view of a trench after a first repair process is performed in the method for manufacturing a trench according to an embodiment of the invention.
Fig. 7 is a schematic cross-sectional view of a trench according to an embodiment of the present invention after a second etching process is performed.
Fig. 8 is a schematic cross-sectional view of a trench after a second repair process is performed in the method for manufacturing a trench according to an embodiment of the invention.
Fig. 9 is a schematic cross-sectional view of a trench according to an embodiment of the invention after forming a filling material layer.
Fig. 10 is a schematic cross-sectional view of a trench according to an embodiment of the invention after removing an alumina layer.
Wherein, the reference numerals are as follows:
10-a substrate; a 20-alumina layer; a 30-silicon oxide layer; 40-patterning the photoresist layer; 50-opening; 60-grooves; 70-layer of filler material.
Detailed Description
The invention will be described in further detail with reference to the drawings and the specific embodiments thereof in order to make the objects, advantages and features of the invention more apparent. It should be noted that the drawings are in a very simplified form and are not drawn to scale, merely for convenience and clarity in aiding in the description of embodiments of the invention. Furthermore, the structures shown in the drawings are often part of actual structures. In particular, the drawings are shown with different emphasis instead being placed upon illustrating the various embodiments.
As used in this disclosure, the singular forms "a," "an," and "the" include plural referents, the term "or" are generally used in the sense of comprising "and/or" and the term "several" are generally used in the sense of comprising "at least one," the term "at least two" are generally used in the sense of comprising "two or more," and the term "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying any relative importance or number of features indicated. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
Fig. 2 is a flowchart of a method for preparing a trench according to this embodiment. Referring to fig. 2, the present invention provides a method for preparing a trench, which includes:
step S1: providing a substrate, wherein an aluminum oxide layer, a silicon oxide layer and a graphical photoresist layer are sequentially formed on the substrate;
step S2: performing a first etching process, sequentially etching the silicon oxide layer and the aluminum oxide layer by taking the patterned photoresist layer as a mask to form an opening penetrating through the silicon oxide layer and the aluminum oxide layer, wherein the side wall of the opening is provided with a plurality of protrusions, and the patterned photoresist layer is synchronously etched and removed when the opening is formed;
step S3: performing a first repair process to remove protrusions of the sidewalls of the opening to smooth the sidewalls of the opening;
step S4: executing a second etching process, etching the substrate downwards along the opening by taking the silicon oxide layer and the aluminum oxide layer as masks so as to form a groove in the substrate, and synchronously etching and removing the silicon oxide layer when the groove is formed;
step S5: performing a second repair process to make the side wall of the trench vertical;
step S6: and removing the aluminum oxide layer.
Fig. 3 is a schematic cross-sectional view of a substrate provided in the method for manufacturing a trench according to the present embodiment. Fig. 4 is a schematic cross-sectional view of a trench in the method for manufacturing a trench according to the present embodiment after a first etching process is performed to etch a silicon oxide layer. Fig. 5 is a schematic cross-sectional view of the trench manufacturing method according to the present embodiment after a first etching process is performed to etch the alumina layer. Fig. 6 is a schematic cross-sectional view of the trench in the method for manufacturing a trench according to the present embodiment after the first repair process is performed. Fig. 7 is a schematic cross-sectional view of the trench preparation method according to the present embodiment after performing the second etching process. Fig. 8 is a schematic cross-sectional view of the trench manufacturing method according to the present embodiment after performing the second repair process. Fig. 9 is a schematic cross-sectional view of the trench in the method for manufacturing a trench according to the present embodiment after forming a filling material layer. Fig. 10 is a schematic cross-sectional view of the trench in the method for manufacturing a trench according to the present embodiment after removing the alumina layer. The method for preparing the trench provided in this embodiment is described in detail below with reference to fig. 3 to 10.
Referring to fig. 3, step S1 is performed: the substrate 10 is provided, and the substrate 10 may be a silicon substrate, a gallium arsenide substrate, a germanium-silicon substrate, or a fully depleted silicon-on-insulator substrate. A device structure may be formed in the substrate 10, and the device structure is not limited to a power device, a memory device, and a sensor device in this embodiment. An aluminum oxide layer 20, a silicon oxide layer 30, and a patterned photoresist layer 40 are sequentially formed on a substrate 10; in this embodiment, the alumina layer 20 can provide a higher etching selectivity, and the patterned photoresist layer 40 is not required to be formed again to be thicker when the alumina layer 20 is formed, so that the thickness of the patterned photoresist layer 40 can be reduced, which is beneficial to reducing the cost.
Referring to fig. 3 to 5, step S2 is performed: a first etching process is performed to sequentially etch the silicon oxide layer 30 and the aluminum oxide layer 20 using the patterned photoresist layer 40 as a mask to form an opening 50 through the silicon oxide layer 30 and the aluminum oxide layer 20. In the present embodiment, the process gas of the first etching process includes a gas containing fluorine and sulfur, and is not limited to the above-described process gas; the sidewalls of the opening 50 after the first etching process have protrusions (corrugated in shape as shown in phantom in fig. 5) that affect the subsequent formation of more vertical trenches.
Specifically, a first etching process is performed, the patterned photoresist layer 40 is used as a mask to etch the silicon oxide layer 30 to form an opening 50, and a part of the patterned photoresist layer 40 (see fig. 4) with a thickness is removed by synchronous etching in the first etching process; next, the first etching process is continued to etch the alumina layer 20 down the opening 50 such that the opening 50 extends to the surface of the substrate 10 to form the opening 50 penetrating the silica layer 30 and the alumina layer 20, and the patterned photoresist layer 40 (see fig. 5) having the remaining thickness is simultaneously etched and removed under the first etching process, so that the patterned photoresist layer 40 is simultaneously etched and removed when the opening is formed.
Referring to fig. 6, step S3 is performed: and performing a first repair process to remove the protrusions on the side wall of the opening 50 so as to smooth the side wall of the opening 50, thereby facilitating the obtainment of a trench with a precise characteristic dimension. In this embodiment, the first repair process is a micro etching process, and the first repair process etches and removes more protruding portions, so that the side wall of the opening 50 tends to be smooth, and the process gas of the first repair process includes gases including silicon and fluorine and oxygen, and is not limited to the process gases; the repair film layer of the first repair process is thinner, the proportion of the gas containing silicon is 10% -20%, the proportion of the gas containing fluorine is 50% -70%, and the proportion of the gas containing oxygen is 20% -30%, but the repair film layer is not limited to the above. The repair film layer of the first repair process mainly aims at silicon oxide and aluminum oxide, silicon reacts with oxygen to form thin silicon oxide, plasma vertically enters into the opening 50 to react with the protrusions in a contact manner to realize micro etching of the protrusions so as to remove the protrusions, and the vertical smooth part is protected by the thin silicon oxide and has the same movement direction as the plasma, so that the vertical smooth part is not damaged; in addition, the fluorine plasma forms AlF with raised aluminum ions 3 And then is pumped away.
Referring to fig. 6 and fig. 7, step S4 is performed: a second etching process is performed to etch the substrate 10 down the opening 50 with the silicon oxide layer 30 and the aluminum oxide layer 20 as a mask to form a trench 60 in the substrate 10. In the present embodiment, the second etching process is performed, and the silicon oxide layer 30 is gradually etched and lost until being removed while the silicon oxide layer 30 and the aluminum oxide layer 20 are used as masks to etch the substrate 10, so that the silicon oxide layer 30 is simultaneously etched and removed when the trench 60 is formed. In this embodiment, the second etching process includes a deposition process and an etching process, where the deposition process and the etching process are performed in a circulating and alternating manner, the circulation time of the deposition process and the etching process is set by the etcher, and a polymer is formed on the sidewall by the deposition process, so that the polymer can weaken and prevent the etching process from etching laterally, and is favorable for obtaining a trench with a precise feature size, and etching downwards by the etching process. Wherein the process gas of the deposition process includes a fluorine-and-carbon-containing gas, and the process gas of the etching process includes a fluorine-and-sulfur-containing gas, not limited to the above-mentioned process gases. In this embodiment, the aspect ratio of the trench 60 is greater than 20:1, and after the second etching process is performed to form the trench 60, the sidewalls of the trench 60 are substantially vertical, but still have partial protrusions (in the shape of a corrugation).
Referring to fig. 8, step S5 is performed: a second repair process is performed to make the sidewalls of the trench 60 vertical to obtain a high aspect ratio and vertical trench 60. In this embodiment, the second repair process is a micro-etching process, and the second repair process etches and removes more protruding parts of the side wall of the trench 60, so that the side wall of the trench 60 tends to be smooth, and the process gas of the second repair process includes gas containing silicon and fluorine and oxygen, and is not limited to the process gas; the depth-to-width ratio of the trench 60 to be repaired in the second repair process is large, the gas containing silicon is introduced in a proportion of 20% -30%, the gas containing fluorine is introduced in a proportion of 10% -20%, and the oxygen is introduced in a proportion of 40% -50%, but the method is not limited thereto. Although the process gases of the second repair process and the first repair process are gases containing silicon and fluorine and oxygen, the composition ratio of the process gases can be adjusted according to etching materials, etching amounts and corresponding final profiles to realize corresponding final profiles. The repair film layer of the second repair process is mainly silicon oxide, the silicon and oxygen are regulated to a proper proportion, after the thin silicon oxide layer is formed, the movement route of the plasma is longer, the etching reaction is sufficient, and the protruding part of the side wall of the groove 60 can be removed by micro etching.
Referring to fig. 9 and 10, step S6 is performed: the step of removing the aluminum oxide layer 20 includes: a filling material layer 70 is formed in the trench 60 to fill the trench 60, and in this embodiment, the material of the filling material layer 70 is preferably photoresist, the photoresist has a better fluidity to fill the trench 60, and the photoresist covers the alumina 20 (only filling the trench 60 is shown in fig. 9), and the filling material layer 70 can also be other organic materials. Furthermore, the aluminum oxide layer 20 and the photoresist on the surface of the aluminum oxide layer 20 are removed by oxygen plasma etching, and the photoresist fills the groove 60, so that the side wall of the groove 60 can be protected from being damaged by the bombardment of plasma; and, an ashing process is used to remove the filler material layer 70 (photoresist) to obtain a high aspect ratio and vertical trench 60.
In summary, in the method for manufacturing a trench provided by the present invention, a substrate is provided, on which an alumina layer, a silica layer and a patterned photoresist layer are sequentially formed; performing a first etching process, sequentially etching the silicon oxide layer and the aluminum oxide layer by taking the patterned photoresist layer as a mask to form an opening penetrating through the silicon oxide layer and the aluminum oxide layer, wherein the side wall of the opening is provided with a plurality of protrusions, and the patterned photoresist layer is synchronously etched and removed when the opening is formed; performing a first repair process to remove protrusions of the sidewalls of the opening to smooth the sidewalls of the opening; executing a second etching process, etching the substrate downwards along the opening by taking the silicon oxide layer and the aluminum oxide layer as masks so as to form a groove in the substrate, and synchronously etching and removing the silicon oxide layer when the groove is formed; performing a second repair process to make the side wall of the trench vertical; and removing the aluminum oxide layer. In the invention, the unexpected technical effect is that the side wall of the opening can be repaired by using the first repairing process to provide better opening outline to be transferred into the substrate, and the substrate is etched by using the alumina layer as a mask to provide higher etching selection ratio, so that the side wall of the groove formed by etching is more vertical; and repairing the side wall of the groove by using a second repairing process to further improve the verticality of the side wall of the groove.
The foregoing is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art will make any equivalent substitution or modification to the technical solution and technical content disclosed in the invention without departing from the scope of the technical solution of the invention, and the technical solution of the invention is not departing from the scope of the invention.
Claims (8)
1. A method of forming a trench, comprising:
providing a substrate, wherein an aluminum oxide layer, a silicon oxide layer and a graphical photoresist layer are sequentially formed on the substrate;
a first etching process is carried out, the patterned photoresist layer is used as a mask to etch the silicon oxide layer and the aluminum oxide layer in sequence, so that an opening penetrating through the silicon oxide layer and the aluminum oxide layer is formed, a plurality of protrusions are arranged on the side wall of the opening, and the patterned photoresist layer is synchronously etched and removed when the opening is formed;
removing protrusions on the side wall of the opening to enable the side wall of the opening to be smooth, wherein the process gas of the first repair process comprises silicon-containing gas, fluorine-containing gas and oxygen, the introducing proportion of the silicon-containing gas is 10% -20%, the introducing proportion of the fluorine-containing gas is 50% -70%, and the introducing proportion of the oxygen is 20% -30%;
performing a second etching process, namely etching the substrate downwards along the opening by taking the silicon oxide layer and the aluminum oxide layer as masks so as to form a groove in the substrate, and synchronously etching and removing the silicon oxide layer when the groove is formed;
performing a second repair process to enable the side wall of the groove to be vertical, wherein the process gas of the second repair process comprises silicon-containing gas, fluorine-containing gas and oxygen, the introducing proportion of the silicon-containing gas is 20% -30%, the introducing proportion of the fluorine-containing gas is 10% -20%, the introducing proportion of the oxygen is 40% -50%, and the composition proportion of the process gas of the first repair process and the process gas of the second repair process is adjusted according to etching materials, etching amounts and corresponding final contours; the method comprises the steps of,
and removing the aluminum oxide layer.
2. The method of fabricating a trench of claim 1, wherein the step of forming an opening through the silicon oxide layer and the aluminum oxide layer comprises:
executing the first etching process, etching the silicon oxide layer to form the opening by taking the patterned photoresist layer as a mask, and synchronously etching to remove part of the patterned photoresist layer with the thickness;
and continuing to execute the first etching process, etching the aluminum oxide layer downwards along the opening so that the opening extends to the surface of the substrate to form an opening penetrating through the silicon oxide layer and the aluminum oxide layer, and synchronously etching to remove the patterned photoresist layer with the residual thickness.
3. The method of claim 2, wherein the process gas of the first etching process comprises a fluorine and sulfur containing gas.
4. The method of claim 1, wherein the silicon oxide layer is gradually etched and lost until removed when the substrate is etched down the opening using the silicon oxide layer and the aluminum oxide layer as masks.
5. The method of claim 4, wherein the second etching process comprises a deposition process and an etching process, the deposition process and the etching process being cyclically alternated.
6. The method of claim 5, wherein the process gas for the deposition process comprises a fluorine and carbon containing gas and the process gas for the etching process comprises a fluorine and sulfur containing gas.
7. The method of claim 1, wherein the trench has an aspect ratio greater than 20:1.
8. The method of fabricating a trench of claim 1, wherein the step of removing the aluminum oxide layer comprises:
forming a filling material layer in the groove to fill the groove;
etching to remove the alumina layer; the method comprises the steps of,
and removing the filling material layer.
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