CN1209499C - Etching agent and application for improving etching selectvie ratio - Google Patents
Etching agent and application for improving etching selectvie ratio Download PDFInfo
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- CN1209499C CN1209499C CN 02127845 CN02127845A CN1209499C CN 1209499 C CN1209499 C CN 1209499C CN 02127845 CN02127845 CN 02127845 CN 02127845 A CN02127845 A CN 02127845A CN 1209499 C CN1209499 C CN 1209499C
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Abstract
The present invention relates to an etching agent and the application thereof for enhancing an etching selectivity. The etching agent at least comprises phosphoric acid (Phosphoric Acid; H3PO4) and a soluble silicon (Si) compound, such as a silicon compound containing halogen, or the silicon compound containing halogen and a derivant thereof. When applied to silicon nitride (SiN4)etching, the etching agent can effectively improve the etching selectivity of the silicon nitride and silicon oxide (SiO2) due to hydrolysis reaction between the soluble silicon compound and the water.
Description
(1) technical field
Relevant a kind of etching reagent of the present invention and the application on raising etching selectivity (Etching Selectivity) thereof particularly have the etching reagent of siliceous (Si) compound and are improving silicon nitride (Si relevant for a kind of
3N
4) and silicon oxide (SiO
2) etching selectivity on application.
(2) background technology
In unicircuit, interfere with each other for fear of the operation between the transistor, thereby must between adjacent transistors, add isolation structure, to prevent that locking (Latch Up) or short circuit take place between transistor with electrical isolation capacity.Yet, follow the microminiaturization trend of semiconductor element size, it is soaring to cause the integrated level of element to continue, so that the size of interelement isolation structure also more shows is crucial.
At present, because shallow trench isolation (Shallow Trench Isolation; STI) not only size is little, Flatness is good for the formed isolation structure of technology, has the excellent electrical property isolation effect, more can significantly improve component density.Therefore in integrated circuit manufacture process now, the shallow trench isolation technology widely adopts.
Please refer to Fig. 1 to Fig. 4, they are processing procedure sectional views of existing shallow trench isolation.When making interelement shallow trench isolation, at first capping oxidation silicon layer 102 is used as pad oxide (PadOxide Layer) on semi-conductive base material 100, covers silicon nitride layer 104 again on silicon oxide layer 102.Wherein, silicon oxide layer 102 is the stress that is present in 100 of silicon nitride layer 104 and base materials in order to reduction, silicon nitride layer 104 then be in order in follow-up processing procedure as cmp (the Chemical Mechanical Polishing of shallow trench isolation; CMP) stop layer.Then, cover one deck photoresist layer 106 on silicon nitride layer 104, and utilize this photoresist layer 106 of micro-photographing process patterning, and expose the silicon nitride layer 104 of part.Utilize patterned light blockage layer 106 to be etch mask again, the silicon nitride layer 104 that exposed and beneath silicon oxide layer 102 thereof are carried out etching with base material 100, use the silicon nitride layer 104 of removing part, the silicon oxide layer 102 of part and the base material 100 of part, and in silicon nitride layer 104, silicon oxide layer 102 and base material 100, forming the opening 108 of shallow trench isolation, formed structure is as shown in Figure 1.
After opening 108 forms, remaining photoresist layer 106 removal is exposed silicon nitride layer 104.Form one deck silicon oxide layer 110 again and cover on base material 100 that opening 108 exposed, silicon oxide layer 102, the silicon nitride layer 104, and fill up opening 108, and form structure as shown in Figure 2.
Then, please refer to Fig. 3, utilize the mode of cmp, and be grinding endpoint, remove the silicon oxide layer 110 on the silicon nitride layer 104 with silicon nitride layer 104, and stay be arranged in opening 108 silicon oxide layer 110 to form shallow slot isolation structure 112.After grinding steps is finished, with hot phosphoric acid (Phosphoric Acid; H
3PO etching reagent and the application on the raising etching selectivity thereof) when etching reagent removal silicon nitride layer 104, and expose silicon oxide layer 102.Yet in the time of with hot phosphoric acid etch silicon nitride layer 104, hot phosphoric acid also can be attacked silicon oxide layer 102, and the thickness of silicon oxide layer 102 also thereby produce and change, and causes the uneven thickness of silicon oxide layer 102.
In order to ensure the reliability that follow-up ion is implanted, the silicon oxide layer 102 of this uneven thickness must be removed, and expose base material 100.Form one deck silicon oxide layer 114 again and cover on the base material 100 that is exposed, be used as the sacrificial oxide layer of ion implantation step.Yet, when removing silicon oxide layer 102, mostly be to adopt hydrogen fluoride (HF) to be used as etching reagent, and hydrogen fluoride is not only attacked silicon oxide layer 102, also can attack the silica material that constitutes shallow slot isolation structure 112.Therefore, after silicon oxide layer 102 was removed, hydrogen fluoride can damage shallow slot isolation structure 112, and formed rough surface on shallow slot isolation structure 112, as shown in Figure 4.
In above-mentioned existing shallow trench isolation processing procedure, be subject to etching reagent to the etching selectivity between silicon nitride layer and silicon oxide layer, cause pad oxide impaired and must be removed earlier, form in addition again thickness comparatively uniformly sacrificial oxide layer in order to the carrying out of ion implantation step.Like this, will cause processing procedure more complicated, increase the weight of cost burden.In addition, when removing pad oxide, etching reagent hydrogen fluoride also can hurt the shallow slot isolation structure that silicon oxide is formed, and has a strong impact on processing procedure reliability and yield.
(3) summary of the invention
Therefore, main purpose of the present invention provides a kind of etching reagent, and it is to mix silicon-containing compound in phosphoric acid.By silicon-containing compound and water generates hydrolysis reaction, and help the carrying out of the reaction of phosphoric acid and silicon nitride, thereby can significantly promote the etching selectivity between silicon nitride and the silicon oxide.
Another object of the present invention is etching reagent to be applied in improve on the etching selectivity, etching reagent by being mixed with silicon-containing compound and phosphoric acid is to increase the etching selectivity between silicon nitride and silicon oxide, therefore when removing nitride layer, can effectively keep the thickness of pad oxide.
According to above-described purpose, the invention provides a kind of etching reagent, be applicable to etching of silicon nitride, comprise at least: a phosphoric acid; And one silicon-containing compound mix in the described phosphoric acid, wherein this silicon-containing compound have a concentration between about 90ppm between about 180ppm.This silicon-containing compound is the water-soluble silicon compound, for example halogen-containing silicon compound or halogen-containing silicon compound and derivative thereof etc.
According to above-described purpose, the present invention more provides a kind of application of above-mentioned etching reagent in addition, it is in order to improve the etching selectivity of silicon nitride to silicon oxide, the method of wherein utilizing above-mentioned etching reagent to improve etching selectivity comprises at least: a base material is provided, wherein comprises the one silica layer and the silicon nitride layer that pile up in regular turn on this base material at least; And utilize above-mentioned etching reagent that above-mentioned silicon nitride layer is carried out etching, and use and remove above-mentioned silicon nitride layer, and expose the beneath silicon oxide layer of silicon nitride layer, wherein this etching reagent comprises that at least a phosphoric acid and a silicon-containing compound mix in the phosphoric acid.Above-mentioned silicon-containing compound is a solubility, and this silicon-containing compound for example is halogen-containing silicon compound or halogen-containing silicon compound and derivative thereof etc., and preferable example is silicon chlorides or silicon chlorides and derivative thereof.
Adopt the present invention can obtain to keep, so pad oxide can be used in successive process as sacrificial oxide layer at the thickness that makes the pad oxide below it during the etching nitride layer.Like this, not only can avoid when pad oxide is removed etching reagent also can save manpower and expense that extra making sacrificial oxide layer is produced to the injury that shallow slot isolation structure caused.Thereby can improve processing procedure reliability and good rate, and reduce the expenditure of processing procedure cost.
For further specifying purpose of the present invention, constructional feature and effect, the present invention is described in detail below with reference to accompanying drawing.
(4) description of drawings
Fig. 1 to Fig. 4 is the processing procedure sectional view of existing shallow trench isolation; And
Fig. 5 to Fig. 8 is the processing procedure sectional view of the shallow trench isolation of a preferred embodiment of the present invention.
(5) embodiment
The present invention discloses a kind of etching reagent and in the application that improves on the etching selectivity, this etching reagent comprises phosphoric acid and silicon-containing compound at least.By silicon-containing compound can with the characteristic of water generates hydrolysis reaction, can make etching reagent that the etching selectivity of silicon nitride and silicon oxide is obtained effectively to promote, and then reach the purpose of the thickness of keeping pad oxide.In order to make narration of the present invention more detailed and complete, can be with reference to the diagram of following description and cooperation Fig. 5 to Fig. 8.
Please refer to Fig. 5 to Fig. 8, they are processing procedure sectional views of the shallow trench isolation of a preferred embodiment of the present invention.The making of shallow slot isolation structure of the present invention, at first be with for example sedimentary mode capping oxidation silicon layer 202 on semi-conductive base material 200, form silicon nitride layer 204 in for example sedimentary mode again and cover on the silicon oxide layer 202, wherein the material of base material 200 can for example be a silicon.Above-mentioned silicon oxide layer 202 is called pad oxide again, can be used as the stress buffer between silicon nitride layer 204 and the base material 200, and silicon nitride layer 204 then can be used as the grinding stop layer in the cmp step of shallow trench isolation material.Then, form photoresist layer 206 and cover on the silicon nitride layer 204, and for example utilize that the technology of little shadow forms the pattern of shallow trench in photoresist layer 206, and expose silicon nitride layer 204 partly.After finishing the patterning of photoresist layer 206, by for example etched mode, and be etch mask with photoresist layer 206, the silicon nitride layer 204 that removal photoresist layer 206 is exposed and beneath silicon oxide layer 202 and base material 200 partly, and in the base material 200 of the silicon oxide layer 202 of the silicon nitride layer 204 of part, part and part, form the opening 208 of shallow trench isolation, as shown in Figure 5.
After the opening 208 of shallow trench isolation forms, divest remaining photoresist layer 206, and expose silicon nitride layer 204.At this moment, with for example high density plasma CVD (High Density PlasmaChemical Vapor Deposition; HDP CVD) mode forms silicon oxide layer 210 and covers on base material 200 that opening 208 exposed and silicon oxide layer 202 and the silicon nitride layer 204, and makes this silicon oxide layer 210 fill up opening 208, and forms structure as shown in Figure 6.
After silicon oxide layer 210 fills up opening 208, utilize for example mode of cmp, and be grinding endpoint with silicon nitride layer 204, remove the silicon oxide layer 210 of part, silicon oxide layer 210 beyond the opening 208 is removed, and in opening 208, forming shallow slot isolation structure 212, formed structure is as shown in Figure 7.
Please refer to Fig. 8, after shallow slot isolation structure 212 forms, utilize etching reagent that silicon nitride layer 204 is carried out etching, use and remove residual silicon nitride layer 204, and expose silicon oxide layer 202.Wherein, etching reagent of the present invention comprises phosphoric acid and silicon-containing compound at least, and this silicon-containing compound belongs to water-soluble.In addition, the concentration of this silicon-containing compound is preferably between about 90ppm between about 180ppm.Yet silicon-containing compound can change its addition according to process requirement, and its concentration is not limited to the above.And above-mentioned silicon-containing compound can for example be halogen-containing silicon compound or halogen-containing silicon compound and derivative thereof, for example silicon chlorides or silicon chlorides and derivative thereof etc.
Since silicon-containing compound can with the water generates hydrolysis reaction, therefore help phosphoric acid and silicon nitride reaction, can significantly improve the etching selectivity of etching reagent to silicon nitride and silicon oxide.In a preferred embodiment of the present invention, the etching reagent that phosphoric acid and silicon-containing compound constituted can be promoted to the etching selectivity of silicon oxide silicon nitride about 50 from about 30, even can reach more than 60.In addition, silicon-containing compound is behind hydrolysis reaction, and the by product that is generated can't produce wafer and impact.For example, if selected silicon-containing compound is silicon chlorides, then the by product that is generated is a hydrogenchloride, and that hydrogenchloride also belongs to is water-soluble, can't produce bad influence to wafer.
Because etching reagent of the present invention has excellent etching selectivity to silicon nitride and silicon oxide, when therefore utilizing this etching reagent to remove silicon nitride layer 204, can significantly reduce the etching of etching reagent, and make the thickness of silicon oxide layer 202 can obtain effectively to keep silicon oxide layer 202.Except that this, also can avoid the shallow slot isolation structure 212 of silicon oxide material to suffer the injury of etching reagent simultaneously.
In addition, owing to the thickness acquisition of silicon oxide layer 202 is kept, so the thickness uniformity coefficient of silicon oxide layer 202 can obtain effective improvement.Like this, silicon oxide layer 202 can directly be used as sacrificial oxide layer, and forms sacrificial oxide layer more in addition after not needing earlier silicon oxide layer 202 to be removed.Not only can alleviate the processing procedure burden, more can improve the reliability of processing procedure.
An advantage of the present invention is exactly because be mixed with water miscible silicon-containing compound in the etching reagent of the present invention, therefore can reach and significantly improve the purpose of etching reagent to the etching selectivity of silicon nitride and silicon oxide.
Another advantage of the present invention is exactly because application etching reagent of the present invention can effectively promote the etching selectivity between silicon nitride and silicon oxide, therefore can obtain the good pad oxide of thickness uniformity coefficient after silicon nitride layer is removed.
Another advantage of the present invention is exactly because the thickness of pad oxide obtains to keep, and can not need to make separately sacrificial oxide layer again, therefore can simplify fabrication steps, reduces the processing procedure cost.
An advantage more of the present invention is exactly because do not need additionally to make sacrificial oxide layer, therefore can improve the quality of shallow slot isolation structure, to promote processing procedure reliability and good rate.
Certainly, those of ordinary skill in the art will be appreciated that, above embodiment is used for illustrating the present invention, and be not to be used as limitation of the invention, as long as in connotation scope of the present invention, all will drop in the scope of claims of the present invention variation, the modification of the above embodiment.
Claims (6)
1. an etching reagent is applicable to etching of silicon nitride, it is characterized in that, this etching reagent comprises at least:
Phosphoric acid; And
One silicon-containing compound mixes in this phosphoric acid, and wherein this silicon-containing compound has finite concentration; This silicon-containing compound is water-soluble;
The concentration of this silicon-containing compound is between between the 90ppm to 180ppm.
2. etching reagent as claimed in claim 1 is characterized in that this silicon-containing compound comprises halogen-containing silicon compound at least.
3. etching reagent as claimed in claim 1 is characterized in that this silicon-containing compound comprises silicon chlorides at least.
4. a method that improves etching selectivity is characterized in that, comprises at least:
One base material is provided, wherein, comprises the one silica layer and the silicon nitride layer that pile up in regular turn on this base material at least; And
With this silicon nitride layer of an etchant etching, use and remove this silicon nitride layer, and expose this silicon oxide layer, wherein, this etching reagent comprises that at least a phosphoric acid and a silicon-containing compound mix in this phosphoric acid; This silicon-containing compound is water-soluble;
The concentration of this silicon-containing compound is between between the 90ppm to 180ppm.
5. the method for raising etching selectivity as claimed in claim 4 is characterized in that, this silicon-containing compound comprises halogen-containing silicon compound at least.
6. the method for raising etching selectivity as claimed in claim 4 is characterized in that, this silicon-containing compound comprises silicon chlorides at least.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 02127845 CN1209499C (en) | 2002-08-01 | 2002-08-01 | Etching agent and application for improving etching selectvie ratio |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 02127845 CN1209499C (en) | 2002-08-01 | 2002-08-01 | Etching agent and application for improving etching selectvie ratio |
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| CN1472361A CN1472361A (en) | 2004-02-04 |
| CN1209499C true CN1209499C (en) | 2005-07-06 |
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| CN 02127845 Expired - Lifetime CN1209499C (en) | 2002-08-01 | 2002-08-01 | Etching agent and application for improving etching selectvie ratio |
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Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102569019B (en) * | 2010-12-17 | 2014-06-04 | 无锡华润上华半导体有限公司 | Shallow trench isolation forming method |
| JP6009268B2 (en) * | 2012-08-09 | 2016-10-19 | 芝浦メカトロニクス株式会社 | Cleaning liquid generating apparatus, cleaning liquid generating method, substrate cleaning apparatus, and substrate cleaning method |
| CN103208421B (en) * | 2013-03-14 | 2015-12-09 | 上海华力微电子有限公司 | A kind of method improving silicon nitride layer and oxide layer etching selection ratio |
| CN109563407A (en) | 2018-11-13 | 2019-04-02 | 长江存储科技有限责任公司 | The additive of phosphoric acid etch agent |
| CN111925800B (en) * | 2020-08-14 | 2022-02-01 | 上海新阳半导体材料股份有限公司 | Etching solution composition, preparation method and application thereof |
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