CN108054092B - Polysilicon filling method - Google Patents
Polysilicon filling method Download PDFInfo
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- CN108054092B CN108054092B CN201711423763.7A CN201711423763A CN108054092B CN 108054092 B CN108054092 B CN 108054092B CN 201711423763 A CN201711423763 A CN 201711423763A CN 108054092 B CN108054092 B CN 108054092B
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- H01—ELECTRIC ELEMENTS
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- 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
- H01L21/28—Manufacture of electrodes on semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/268
- H01L21/283—Deposition of conductive or insulating materials for electrodes conducting electric current
- H01L21/288—Deposition of conductive or insulating materials for electrodes conducting electric current from a liquid, e.g. electrolytic deposition
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Abstract
The invention provides a polysilicon filling method, which comprises the following steps: forming a silicon dioxide mask on a silicon substrate, and etching the silicon substrate to form a wide-size groove; filling polycrystalline silicon in the wide-size groove, carrying out back-etching treatment on the polycrystalline silicon, and forming a pit on the surface of the polycrystalline silicon after the back-etching treatment; filling the pits with liquid silicon dioxide, and curing to form a silicon dioxide layer; back-etching the silicon dioxide layer until a sharp corner area at the edge of the polycrystalline silicon of the wide-size groove is exposed; oxidizing the polycrystalline silicon in the sharp-angled area into silicon dioxide, and etching back the silicon dioxide again; and repeating the oxidation and silicon dioxide back etching steps of the sharp-angled area until the surface of the polycrystalline silicon in the wide-size groove is flat.
Description
[ technical field ] A method for producing a semiconductor device
The invention relates to the technical field of semiconductor chip manufacturing, in particular to a polycrystalline silicon filling method suitable for a wide groove.
[ background of the invention ]
In semiconductor chip manufacturing, the need to fill trenches and etch back the fill often arises. However, in the process of trench filling using polysilicon as a filler and etching back the filler, the following phenomena often occur: for the trench with larger opening size, the filling effect of the filler is worse, and after the filler is etched back, the appearance of the surface of the filler is worse, such as occurrence of deep pits and the like. Therefore, the above-mentioned problem of the wide-sized trench causes a series of difficulties in the subsequent process.
Accordingly, there is a need to provide a method for filling polysilicon to solve the above-mentioned problems of the prior art.
[ summary of the invention ]
One of the objectives of the present invention is to provide a method for filling polysilicon.
The polysilicon filling method provided by the invention comprises the following steps: forming a silicon dioxide mask on a silicon substrate, and etching the silicon substrate to form a wide-size groove; filling polycrystalline silicon in the wide-size groove, carrying out back-etching treatment on the polycrystalline silicon, and forming a pit on the surface of the polycrystalline silicon after the back-etching treatment; filling the pits with liquid silicon dioxide, and curing to form a silicon dioxide layer; back-etching the silicon dioxide layer until a sharp corner area at the edge of the polycrystalline silicon of the wide-size groove is exposed; oxidizing the polycrystalline silicon in the sharp-angled area into silicon dioxide, and etching back the silicon dioxide again; and repeating the oxidation and silicon dioxide back etching steps of the sharp-angled area until the surface of the polycrystalline silicon in the wide-size groove is flat.
As an improvement of the polysilicon filling method provided in the present invention, in a preferred embodiment, after repeating the above steps of oxidizing the sharp corner regions and etching back silicon dioxide, the surface of the polysilicon inside the wide-sized recess is lower than the surface of the silicon substrate to form a shallow recess.
As an improvement of the polysilicon filling method provided in the present invention, in a preferred embodiment, the method further includes: and refilling polysilicon in the shallow grooves, and carrying out back etching treatment to planarize the surface of the polysilicon and the surface of the silicon substrate.
As an improvement of the polysilicon filling method provided in the present invention, in a preferred embodiment, the step of forming a silicon dioxide mask on a silicon substrate and etching the silicon substrate to form the wide-dimension groove includes: providing a silicon substrate, and growing an oxide layer on the surface of the silicon substrate, wherein the oxide layer is used as the silicon dioxide mask; and forming an etching window on the silicon dioxide mask, and etching the wide-size groove on the silicon substrate based on the etching window.
As an improvement of the polysilicon filling method provided in the present invention, in a preferred embodiment, the wide trench is formed by etching using a dry etching process.
As an improvement of the polysilicon filling method provided in the present invention, in a preferred embodiment, the polysilicon filling is not only filled into the wide-dimension groove, but also covers the surface of the silicon dioxide mask.
As an improvement of the polysilicon filling method provided in the present invention, in a preferred embodiment, the silicon dioxide layer is cured to not only fill the pits of the polysilicon but also cover the silicon dioxide mask.
As an improvement of the polysilicon filling method provided in the present invention, in a preferred embodiment, during the back etching of the silicon dioxide layer, the silicon dioxide mask is partially etched to reduce the thickness.
As an improvement of the polysilicon filling method provided in the present invention, in a preferred embodiment, the polysilicon in the pointed region is converted into silicon dioxide pointed corners by a surface low temperature oxidation treatment.
As an improvement to the polysilicon filling method provided in the present invention, in a preferred embodiment, after repeating the above steps of oxidizing the sharp corner regions and etching back the silicon dioxide, the thickness of the silicon dioxide mask on the surface of the silicon substrate is gradually reduced until it is completely etched away.
Compared with the prior art, the polycrystalline silicon filling method provided by the invention is mainly characterized in that after polycrystalline silicon is filled and etched back, pits are filled by using liquid silicon dioxide, then silicon dioxide is etched back, the polycrystalline silicon in the sharp corner area is oxidized into silicon dioxide, then etching is carried out, and the process is repeated until the surface of the polycrystalline silicon is flattened, so that the filling effect of the polycrystalline silicon is improved, pits cannot be generated in the subsequent etching back step, the surface appearance of the polycrystalline silicon is ensured, and the performance of a device is improved.
[ description of the drawings ]
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without inventive efforts, wherein:
FIG. 1 is a schematic flow chart illustrating a polysilicon filling method according to an embodiment of the present invention;
fig. 2 to 9 are schematic diagrams illustrating process steps of the polysilicon filling method shown in fig. 1.
[ detailed description ] embodiments
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a polysilicon filling method, which aims to solve the problems that the polysilicon filling effect of a wide-size groove is poor and pits are easy to generate after back etching in the prior art.
Please refer to fig. 1, which is a flowchart illustrating a polysilicon filling method according to an embodiment of the present invention. The polysilicon filling method mainly comprises the following steps:
step S1, forming a silicon dioxide mask on a silicon substrate, and etching the silicon substrate to form a wide-size groove;
specifically, referring to fig. 2, a silicon substrate is provided, and an oxide layer is grown on the surface of the silicon substrate through a growth process, where the oxide layer may be specifically a silicon dioxide layer, and may be used as the silicon dioxide mask; then, forming an etching window on the silicon dioxide mask through an etching process, wherein the etching window is mainly used for etching a wide-size groove; and after the etching window is formed, etching a wide-size groove on the silicon substrate based on the etching window by using a dry etching process.
Step S2, filling polysilicon in the wide-size groove;
specifically, referring to fig. 3, after the wide trench is formed, polysilicon filling is performed inside the wide trench, wherein the polysilicon not only fills the wide trench but also covers the surface of the silicon dioxide mask.
Step S3, carrying out back etching treatment on the polysilicon to remove the polysilicon on the surface of the silicon dioxide mask;
specifically, referring to fig. 4, after the polysilicon is filled into the wide-sized recess, a polysilicon etching back process may be used to etch back the polysilicon on the surface of the silicon dioxide mask, so as to remove the polysilicon on the surface of the silicon dioxide mask. During the etch back process, the polysilicon inside the wide-sized grooves will be pitted, as shown in fig. 4.
Step S4, filling pits formed after the polysilicon back etching with liquid silicon dioxide, and curing to form a silicon dioxide layer;
specifically, referring to fig. 5, in step S4, the pits formed by etching back the polysilicon may be coated and filled with liquid silicon dioxide (SOG), and after the liquid silicon dioxide is coated, the pits and the silicon dioxide mask are cured to form a silicon dioxide layer, so that the pits of the polysilicon and the silicon dioxide mask are covered by the silicon dioxide layer.
Step S5, back-etching the silicon dioxide layer until the sharp corner area of the edge of the polysilicon of the wide-size groove is exposed;
specifically, referring to fig. 6, after the silicon dioxide layer is formed, the silicon dioxide layer may be etched back, and during the etching back of the silicon dioxide layer, the silicon dioxide mask is partially etched to reduce the thickness, except that the silicon dioxide layer on the surface of the silicon dioxide mask is removed. Furthermore, the etching back of the silicon dioxide layer needs to ensure that at least the silicon dioxide layer and the silicon dioxide mask above the sharp corner region at the edge of the wide-sized groove are etched away, so that the sharp corner region at the edge of the polysilicon of the wide-sized groove is exposed, as shown in fig. 6.
Step S6, oxidizing the polysilicon in the sharp-angled area into silicon dioxide, and etching back the silicon dioxide again;
specifically, referring to fig. 7, after the sharp corner regions at the polysilicon edges of the wide-sized trenches are exposed, the polysilicon in the sharp corner regions may be oxidized to silicon dioxide sharp corners by a surface low temperature oxidation process. Therefore, after the oxidation treatment, the filling of the pits on the surface of the polycrystalline silicon and the sharp corners of the edges of the polycrystalline silicon are both silicon dioxide, and the sharp corners of the silicon dioxide at the edges of the polycrystalline silicon are positioned above the silicon dioxide filled in the pits. Further, the silicon dioxide sharp corners at the edges of the polysilicon can be etched back again by the silicon dioxide etching back process.
Step S7, repeating the steps of oxidizing the sharp-angled area and etching back silicon dioxide until the surface of the polysilicon in the wide-size groove is flat;
specifically, referring to fig. 8, after repeating the oxidation and silicon dioxide etch back steps of the sharp corner regions, the polysilicon surface inside the wide recess becomes flat, and on the other hand, the thickness of the silicon dioxide mask on the silicon substrate surface is gradually reduced until it is completely etched away. It should be noted that although the surface of the polysilicon inside the wide groove is planarized, the surface of the polysilicon inside the wide groove is actually lower than the surface of the silicon substrate due to multiple oxidation and etching back, so that a step is formed between the polysilicon and the silicon substrate, which is equivalent to that after the above-mentioned series of processes, the depth of the groove is reduced a lot, and becomes a shallow groove.
Step S8, refilling polysilicon in the wide-size groove, and carrying out back etching treatment to planarize the surface of the polysilicon and the surface of the silicon substrate;
specifically, referring to fig. 9, since the depth of the wide recess is reduced by a lot, in step S8, polysilicon may be refilled over the polysilicon of the wide recess and an etching back process may be performed. Since the groove is shallow at this time, the pits are not formed again after the polysilicon is refilled and etched back, which means that the polysilicon surface inside the groove and the silicon substrate surface outside the groove become flat.
Compared with the prior art, the polycrystalline silicon filling method provided by the invention is mainly characterized in that after polycrystalline silicon is filled and etched back, pits are filled by using liquid silicon dioxide, then silicon dioxide is etched back, the polycrystalline silicon in the sharp corner area is oxidized into silicon dioxide, then etching is carried out, and the process is repeated until the surface of the polycrystalline silicon is flattened, so that the filling effect of the polycrystalline silicon is improved, pits cannot be generated in the subsequent etching back step, the surface appearance of the polycrystalline silicon is ensured, and the performance of a device is improved.
While the foregoing is directed to embodiments of the present invention, it will be understood by those skilled in the art that various changes may be made without departing from the spirit and scope of the invention.
Claims (10)
1. A polysilicon filling method, comprising:
forming a silicon dioxide mask on a silicon substrate, and etching the silicon substrate to form a wide-size groove;
filling polycrystalline silicon in the wide-size groove, carrying out back-etching treatment on the polycrystalline silicon, and forming a pit on the surface of the polycrystalline silicon after the back-etching treatment;
filling the pits with liquid silicon dioxide, and curing to form a silicon dioxide layer;
back-etching the silicon dioxide layer until a sharp corner area at the edge of the polycrystalline silicon of the wide-size groove is exposed;
oxidizing the polycrystalline silicon in the sharp-angled area into silicon dioxide, and etching back the silicon dioxide again;
and repeating the oxidation and silicon dioxide back etching steps of the sharp-angled area until the surface of the polycrystalline silicon in the wide-size groove is flat.
2. The method of claim 1, wherein after repeating the oxidizing and silicon dioxide back etching steps of the pointed region, the surface of the polysilicon within the wide dimension recess is below the surface of the silicon substrate to form a shallow trench.
3. The method of claim 2, further comprising: and refilling polysilicon in the shallow grooves, and carrying out back etching treatment to planarize the surface of the polysilicon and the surface of the silicon substrate.
4. The method of claim 1, wherein the steps of forming a silicon dioxide mask on a silicon substrate and etching the silicon substrate to form the wide dimension recess comprises:
providing a silicon substrate, and growing an oxide layer on the surface of the silicon substrate, wherein the oxide layer is used as the silicon dioxide mask;
and forming an etching window on the silicon dioxide mask, and etching the wide-size groove on the silicon substrate based on the etching window.
5. The method of claim 4, wherein the wide trench is formed by etching using a dry etching process.
6. The method of claim 4, wherein said polysilicon filling is followed by filling not only to said wide dimension recess but also to cover the surface of said silicon dioxide mask.
7. The method of claim 1, wherein the silicon dioxide layer after curing not only fills the polysilicon pits, but also covers the silicon dioxide mask.
8. The method of claim 7, wherein the silicon dioxide mask is partially etched during the etching back of the silicon dioxide layer to reduce the thickness.
9. The method of claim 8, wherein the polysilicon in the cusp region is converted to silicon dioxide cusps by a surface low temperature oxidation process.
10. The method of claim 9, wherein the steps of oxidizing the sharp regions and etching back the silicon dioxide are repeated, and the thickness of the silicon dioxide mask on the surface of the silicon substrate is further gradually reduced until the silicon dioxide mask is completely etched away.
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| CN201711423763.7A CN108054092B (en) | 2017-12-25 | 2017-12-25 | Polysilicon filling method |
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| CN201711423763.7A CN108054092B (en) | 2017-12-25 | 2017-12-25 | Polysilicon filling method |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5728621A (en) * | 1997-04-28 | 1998-03-17 | Chartered Semiconductor Manufacturing Pte Ltd | Method for shallow trench isolation |
| CN102468128A (en) * | 2010-11-09 | 2012-05-23 | 上海华虹Nec电子有限公司 | Method for forming deep-trench polysilicon |
| CN104103681A (en) * | 2014-07-02 | 2014-10-15 | 武汉新芯集成电路制造有限公司 | Floating gate structure and manufacturing method thereof |
| CN107248494A (en) * | 2017-07-12 | 2017-10-13 | 张欣 | A kind of polysilicon fill method for being applied to wide dimensioned trenches |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US7208404B2 (en) * | 2003-10-16 | 2007-04-24 | Taiwan Semiconductor Manufacturing Company | Method to reduce Rs pattern dependence effect |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5728621A (en) * | 1997-04-28 | 1998-03-17 | Chartered Semiconductor Manufacturing Pte Ltd | Method for shallow trench isolation |
| CN102468128A (en) * | 2010-11-09 | 2012-05-23 | 上海华虹Nec电子有限公司 | Method for forming deep-trench polysilicon |
| CN102468128B (en) * | 2010-11-09 | 2013-09-11 | 上海华虹Nec电子有限公司 | Method for forming deep-trench polysilicon |
| CN104103681A (en) * | 2014-07-02 | 2014-10-15 | 武汉新芯集成电路制造有限公司 | Floating gate structure and manufacturing method thereof |
| CN107248494A (en) * | 2017-07-12 | 2017-10-13 | 张欣 | A kind of polysilicon fill method for being applied to wide dimensioned trenches |
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Effective date of registration: 20200512 Address after: 751600 the Ningxia Hui Autonomous Region Wuzhong City Qingtongxia new material base Applicant after: Ningxia Haisheng Industry Co., Ltd Address before: 518000 Guangdong city of Shenzhen province Baoan District Fuyong Street Peace community Junfeng Industrial Zone A3 building the first floor Applicant before: SHENZHEN JINGTE SMART MANUFACTURING TECHNOLOGY Co.,Ltd. |