Etching composition, method for etching insulating film of semiconductor device using the same, and method for manufacturing semiconductor device
阅读说明：本技术 蚀刻组合物，使用其蚀刻半导体器件的绝缘膜的方法以及制备半导体器件的方法 (Etching composition, method for etching insulating film of semiconductor device using the same, and method for manufacturing semiconductor device ) 是由 金喆禹 李光国 郭宰熏 金荣汎 辛姃河 李宗昊 赵珍耿 于 2020-09-02 设计创作，主要内容包括：蚀刻组合物,使用其蚀刻半导体器件的绝缘膜的方法以及制备半导体器件的方法。一种蚀刻组合物,其包括磷酸、包含至少一个硅(Si)原子的硅烷化合物和由以下式1表示的铵盐：[式1]其中：L~1-L~3独立地为取代或未取代的亚烃基,R~1-R~4独立地为氢、取代或未取代的烃基基团,以及X~(n-)为n价阴离子,其中n为1-3的整数。(An etching composition, a method of etching an insulating film of a semiconductor device using the same, and a method of manufacturing a semiconductor device. An etching composition comprising phosphoric acid, a silane compound containing at least one silicon (Si) atom, and an ammonium salt represented by the following formula 1: [ formula 1] Wherein: l is 1 ‑L 3 Independently is a substituted or unsubstituted alkylene group, R 1 ‑R 4 Independently hydrogen, a substituted or unsubstituted hydrocarbyl group, and X n‑ Is an n-valent anion, wherein n is an integer from 1 to 3.)
1. An etching composition, comprising:
phosphoric acid, a silane compound containing at least one silicon (Si) atom, and an ammonium salt represented by the following formula 1:
[ formula 1]
Wherein:
L1-L3independently a substituted or unsubstituted alkylene group,
R1-R4independently hydrogen, a substituted or unsubstituted hydrocarbyl group, and
Xn-is an n-valent anion, wherein n is an integer from 1 to 3.
2. The etching composition according to claim 1, wherein X is selected from the group consisting of halogen, C1-C10Carboxylate, tosylate, sulfate, mesylate, bisulfate, carbonate, bicarbonate, phosphate, hydrogenphosphate, dihydrogen phosphate, and nitrate.
3. The etching composition of claim 1, wherein L1-L3Independently is substituted or unsubstituted C1-C5An alkylene group.
4. The etching composition of claim 3, wherein L1-L3The same is true.
5. The method of claim 4Wherein L is1-L3is-CH2CH2-or-CH2CH(CH3)-。
6. The etching composition of claim 1, wherein the hydrocarbyl group is substituted or unsubstituted C1-C20Alkyl radicals or substituted or unsubstituted C6-C20An aryl group.
7. The etching composition of claim 1, wherein R1-R3Is hydrogen, and R4Is hydrogen or C1-C20An alkyl group.
8. The etching composition of claim 7, wherein R4Is hydrogen or-CH3。
9. The etching composition of claim 1, wherein formula 1 is selected from the group consisting of the following formula 1-formula 14:
wherein OAc, OTs and OMs represent acetate, p-toluenesulfonate and methanesulfonate, respectively.
10. The etching composition according to claim 1, wherein the silane compound is represented by the following formula 2:
[ formula 2]
Wherein, in the formula 2,
R51-R54independently is hydrogen, a substituted or unsubstituted hydrocarbyl group, or a substituted or unsubstituted heterohydrocarbyl group, and R51-R54Independently of or it existsTwo or more of them form a ring through a heteroatom.
11. The etching composition according to any one of claims 1 to 10, comprising 70 wt% to 95 wt% of the phosphoric acid, 0.001 wt% to 5 wt% of the silane compound, and 0.001 wt% to 10 wt% of the ammonium salt represented by formula 1.
12. A method for etching an insulating film using the etching composition described in any one of claims 1 to 10.
13. A method of making a semiconductor device, comprising:
sequentially forming a tunneling oxide film, a polysilicon film, a buffer oxide film and a pad nitride film on a substrate;
forming a trench by selectively etching the polysilicon film, the buffer oxide film and the pad nitride film;
forming a SOD oxide film to gap-fill the trench;
performing a Chemical Mechanical Polishing (CMP) process on the SOD oxide film using the pad nitride film as a polishing stop film;
removing the pad nitride film by wet etching using the etching composition of any one of claims 1 to 10; and
and removing the buffer oxide film.
Technical Field
The present invention relates to an etching composition, and more particularly, to an etching composition having a high selectivity ratio and capable of selectively removing a nitride film while minimizing an etching rate of an oxide film.
Background
Such as silicon oxide (SiO)2) An oxide film of the film and a nitride film such as a silicon nitride (SiNx) film are representative insulating films. In a semiconductor manufacturing process, a silicon oxide film or a silicon nitride film is used alone or in a form in which one or more films are alternately stacked. In addition, the oxide film or the nitride film is also used as a hard mask for forming a conductive pattern such as a metal wiring.
In the wet etching process for removing the nitride film, a mixture of phosphoric acid and deionized water is generally used. Deionized water is added to prevent a decrease in the etching rate and a change in the etching selectivity to the oxide film. However, there may be a problem in that defects may be generated in the nitride film etch removal process even though the amount of the supplied deionized water varies slightly. In addition, phosphoric acid is strong acid and corrosive, thus causing difficulty in handling.
In order to solve the above problems, there is a conventionally known use in phosphoric acid (H)3PO4) Comprising fluoric acid (HF) and nitric acid (HNO)3) And the like, in order to remove the nitride film. However, this technique results in a decrease in the etching selectivity of the nitride film with respect to the oxide film.
Further, a technique using an etching composition containing phosphoric acid and silicic acid or a silicate is also known; however, silicic acid or silicate has a problem of generating particles that may affect a substrate, and is therefore not suitable for a semiconductor manufacturing process.
Meanwhile, when phosphoric acid is used for a wet etching process to remove a nitride film, since an etching selectivity ratio of the nitride film with respect to an oxide film is lowered, not only the nitride film but also the oxide film such as an SOD oxide film is etched, and thus it may be difficult to adjust an effective field oxide height (EFH). Therefore, a sufficient wet etching time for removing the nitride film may not be ensured, or an additional process may be required, thereby causing a change and adversely affecting it.
Therefore, there is a need for an etching composition having a high selectivity ratio, which selectively etches a nitride film with respect to an oxide film in a semiconductor manufacturing process, and which does not have problems such as generation of particles.
Meanwhile, silane-based additives, which are additives added to conventional etching compositions, have too low solubility to ensure optimal solubility, resulting in the occurrence of particle precipitation and abnormal growth of substrates in the etching solution composition. Such particles may remain on the silicon substrate, causing defects of devices implemented thereon, or causing malfunction of equipment used in the etching or cleaning process.
Further, when the etching composition is stored for a long time, the etching rates of the nitride film and the silicon oxide film are changed, thereby changing the selectivity ratio of the nitride film with respect to the oxide film.
Disclosure of Invention
An aspect of the present invention is to provide an etching composition having a high selectivity ratio, which can selectively remove a nitride film while minimizing etching of an oxide film, without causing problems such as particle generation having adverse effects on device characteristics.
Another aspect of the present invention is to provide an etching composition having excellent storage stability.
Further, another aspect of the present invention is to provide a method of etching an insulating film using the etching composition and a method for manufacturing a semiconductor device.
The invention provides an etching composition. According to an embodiment of the present invention, an etching composition includes phosphoric acid, a silane compound including at least one silicon (Si) atom, and an ammonium salt represented by formula 1:
[ formula 1]
In formula 1, L1-L3Independently is a substituted or unsubstituted alkylene group, R1-R4Independently is hydrogen, a substituted or unsubstituted hydrocarbyl group, and Xn-Is an n-valent anion, wherein n is an integer from 1 to 3.
X may be selected from halogen, C1-C10Carboxylate, tosylate, sulfate, mesylate, bisulfate, carbonate, bicarbonate, phosphate, hydrogenphosphate, dihydrogen phosphate, and nitrate.
L1-L3May independently be substituted or unsubstituted C1-C5Alkylene groups, and preferably the same. For example, L1-L3Can be-CH2CH2-or-CH2CH(CH3)-。
The hydrocarbyl group may be substituted or unsubstituted C1-C20Alkyl radicals or substituted or unsubstituted C6-C20An aryl group.
For example,R1-R3may be hydrogen, and R4Can be hydrogen or C1-C20An alkyl group. More specifically, R4May be hydrogen or-CH3。
The ammonium salt of formula 1 may be selected from the following formulae 1-14:
wherein OAc, OTs and OMs represent acetate, p-toluenesulfonate and methanesulfonate, respectively.
The silane compound may be represented by the following formula 2:
[ formula 2]
In formula 2, R51-R54Independently is hydrogen, a substituted or unsubstituted hydrocarbyl group, or a substituted or unsubstituted heterohydrocarbyl group, and R51-R54Independently exist or two or more of them form a ring through a heteroatom.
The etching composition of each of the above example embodiments may include 70 wt% to 95 wt% of phosphoric acid, 0.001 wt% to 5 wt% of a silane compound, and 0.001 wt% to 10 wt% of an ammonium salt represented by formula 1.
The present invention provides a method for etching an insulating film using the above-described etching composition, and a method for manufacturing a semiconductor device including the method for etching an insulating film.
Drawings
The above and other aspects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
fig. 1 and 2 are exemplary process cross-sectional views illustrating a device isolation process of a flash memory device.
Detailed Description
The present invention provides an etching composition, particularly an etching composition having a high selectivity ratio, which is capable of selectively removing a nitride film while minimizing etching of an oxide film, and has excellent storage stability.
The etching composition of the present invention comprises phosphoric acid. Phosphoric acid can react with silicon nitride to etch the silicon nitride film and react with silicon nitride as shown in the following equation (1):
3Si3N4+27H2O+4H3PO4→4(NH4)3PO4+9SiO2H2O(1)。
the etching composition of the present invention comprises an ammonium salt represented by the following formula 1:
[ formula 1]
In formula 1, L1-L3Independently a substituted or unsubstituted alkylene group. L is1-L3May independently be substituted or unsubstituted C1-C5Alkylene radicals, e.g. CH2CH2-or-CH2CH(CH3)-。L1-L3May be different from or the same as each other.
In formula 1, R1-R4Independently hydrogen, a substituted or unsubstituted hydrocarbyl group. The substituted or unsubstituted hydrocarbyl group may be substituted or unsubstituted C1-C20Alkyl radicals or substituted or unsubstituted C6-C20An aryl group. R1-R4May be different from each other, or two or more of them may be the same. For example, R1-R3May be hydrogen, and R4Can be hydrogen or C1-C20An alkyl group.
In formula 1, Xn-May be an n-valent anion, preferably itWherein n is an integer of 1 to 3. For example, X may be a halogen, such as F, Cl, Br, I, and the like. X may also be C selected from, for example, acetate1-C10Carboxylate, tosylate, sulfate, mesylate, bisulfate, carbonate, bicarbonate, phosphate, hydrogenphosphate, dihydrogen phosphate, and nitrate.
The ammonium salt represented by formula 1 provided in the present invention provides structural stability to the silane compound and prevents decomposition or abnormal growth of the silane compound, thereby inhibiting particle formation of the etching compound and etching of silicon oxide.
The ammonium salt contained in the etching composition may be used alone as long as it is represented by formula 1 above, or two or more of them may be mixed for use.
The ammonium salt used in the present invention may be an ammonium salt of the following structural formula (1) to structural formula (14):
wherein OAc, OTs and OMs represent acetate, p-toluenesulfonate and methanesulfonate, respectively.
The ammonium salt of formula 1 may prevent particle formation of the etching composition, and may be added in an amount of 0.001 wt% to 10 wt%, based on the total weight of the etching composition. When the amount of the added ammonium salt is less than 0.001 wt%, it is difficult to obtain the effect of suppressing the formation of particles, and if the amount exceeds 10 wt%, the ammonium salt accelerates the formation of particles.
The content of the ammonium salt of formula 1 may be, for example, 0.001-5 wt%, 0.001-3 wt%, 0.001-2 wt%, 0.001-1 wt%, 0.005-5 wt%, 0.005-3 wt%, 0.005-2 wt%, 0.005-1 wt%, 0.01-5 wt%, 0.01-3 wt%, 0.01-2 wt%, 0.01-1 wt%, 0.05-5 wt%, 0.05-3 wt%, 0.05-2 wt%, 0.05-1 wt%, 0.1-5 wt%, 0.1-3 wt%, 0.1-2 wt%, 0.1-1 wt%, 0.5-5 wt%, 0.5-3 wt%, 0.5-2 wt%, or 0.5-1 wt%.
The etching composition includes a silane compound. Any silane compound containing one or more silicon atoms may be suitably used in the present invention. More preferably, the silane compound may be a silane compound represented by the following formula 2:
[ formula 2]
In formula 2, R51-R54Independently hydrogen, a substituted or unsubstituted hydrocarbyl group (e.g., substituted or unsubstituted C1-C20A hydrocarbyl group), or a substituted or unsubstituted heterohydrocarbyl group (e.g., substituted or unsubstituted C)1-C20A heterohydrocarbyl group). R51-R54May be present independently or two or more of them may form a ring connected through a heteroatom. For example, R51-R54Can be hydrogen, substituted or unsubstituted C1-C20Alkyl radical, substituted or unsubstituted C1-C20Heteroalkyl groups, and the like. In this case, the heteroatom is not particularly limited, but may be N, S, O, P or the like.
The silane compound represented by formula 2 may be included in an amount of 0.005 wt% to 1 wt% based on the total weight of the etching composition.
In addition, the etching composition may further include other ammonium salts in addition to the ammonium salt represented by formula 1.
Ammonium salts are compounds having ammonium ions, and any of those commonly used in the art may be suitable for use in the present invention. Although not particularly limited, the ammonium salt may be, for example, aqueous ammonia, ammonium chloride, ammonium acetate, ammonium phosphate, ammonium persulfate, ammonium sulfate, ammonium fluoride (ammonium fluoride), or the like. These may be used alone or in combination of two or more of them.
In addition, the etching composition of the present invention may further comprise optional additives conventionally used in the art to further improve the etching performance. The additive may be a surfactant, a metal ion chelating agent, a corrosion inhibitor, or the like.
The etching composition of the present invention is used for selectively removing a nitride film from a semiconductor device including an oxide film and a nitride film by etching. The nitride film may include a silicon nitride film, for example, a SiN film, a SiON film, or the like.
Further, the oxide film may be selected from: at least one of a silicon oxide film (e.g., a spin-on dielectric (SOD) film), a High Density Plasma (HDP) film, a thermal oxide film, a borophosphosilicate glass (BPSG) film, a phosphosilicate glass (PSG) film, a borosilicate glass (BSG) film, a Polysilazane (PSZ) film, a Fluorinated Silicate Glass (FSG) film, a Low Pressure Tetraethylorthosilicate (LPTEOS) film, a Plasma Enhanced Tetraethylorthosilicate (PETEOS) film, a High Temperature Oxide (HTO) film, a Medium Temperature Oxide (MTO) film, an Undoped Silicate Glass (USG) film, a spin-on glass (SOG) film, an Advanced Planarization Layer (APL) film, an Atomic Layer Deposition (ALD) film, a plasma enhanced oxide (PE-oxide) film, an O3-tetraethylorthosilicate (O3-TEOS) film, or a combination thereof.
The etching method involving the use of the etching composition of the present invention may be performed by a wet etching method such as dipping, spraying, or the like.
An example of an etching process using the etching composition of the present invention is schematically shown in fig. 1 and 2. Fig. 1 and 2 are exemplary process cross-sectional views illustrating a device isolation process of a flash memory device.
As shown in fig. 1, a tunnel oxide film 11, a polysilicon film 12, a buffer oxide film 13, and a pad nitride film 14 are sequentially formed on a substrate 10, and the polysilicon film 12, the buffer oxide film 13, and the pad nitride film 14 are selectively etched to form a trench. Subsequently, the SOD oxide film 15 is formed until the trench gap is filled, and then a CMP process is performed on the SOD oxide film 15 using the pad nitride film 14 as a polishing stopper film.
As shown in fig. 2, after the pad nitride film 14 is removed by wet etching using a phosphoric acid solution, the buffer oxide film 13 is removed in a washing process. As a result, a device isolation film (separation film)15A is formed in the field area.
The temperature of the etching process may be in the range of 50 to 300 c, preferably in the range of 100 to 200 c, more preferably in the range of 156 to 163 c, and the applicable temperature may be changed if necessary in consideration of other processes and factors.
In this way, according to the method for manufacturing a semiconductor device including an etching process using the etching composition of the present invention, when nitride films and oxide films are alternately stacked or mixed, the nitride films can be selectively etched. In addition, the stability and reliability of the process can be ensured by preventing the generation of particles that have problems in the conventional etching process.
Therefore, such a method can be effectively applied to various processes requiring selective etching of a nitride film with respect to an oxide film in a semiconductor device manufacturing process.
Examples
Hereinafter, the present invention will be described in detail by examples. The following examples relate to examples of the present invention, but the present invention is not limited thereto.
[ Synthesis example 1]
10g triethanolamine was added to a 100mL round bottom flask, followed by 30mL ethanol and stirring.
The mixture was cooled to reach 0 ℃ while maintaining N2Atmosphere, and gradually add 4.1g of acetic acid. The temperature outside the flask was raised to 90 ℃, and the mixture was allowed to react under reflux for 24 hours.
The external temperature was lowered to 40 ℃ and ethanol was removed by distillation under reduced pressure. Vacuum drying was then carried out for 12 hours to obtain ammonium salt additive 1 of the following formula 1:
1H-NMR(DMSO-d6):5.00(broad，4H)，3.71(t，6H)，2.67(t，6H)，1.98(s，3H)
[ Synthesis example 2]
10g of triethanolamine was added to a 100mL round bottom flask, followed by 30mL of acetonitrile and stirring.
The mixture was cooled to reach 0 ℃ while maintaining N2Atmosphere, and 4.3g of dimethyl sulfate were gradually added. The temperature outside the flask was raised to 90 ℃, and the mixture was allowed to react under reflux for 60 hours.
The external temperature was lowered to 25 ℃ and the acetonitrile layer was removed, and then 30mL of acetonitrile was further added to the flask to wash it away.
Vacuum drying was then carried out for 12 hours to obtain ammonium salt additive 2 of the following formula 2:
1H-NMR(DMSO-d6):4.78(broad，3H)，3.81(m，6H)，3.49(t，6H)，3.12(s，3H)
[ Synthesis example 3]
5g of triisopropanolamine was added to a 100mL round bottom flask, followed by 30mL of ethanol and stirring.
The mixture was cooled until 0 ℃ was reached and 1.65mL of 70% nitric acid was gradually added. The temperature outside the flask was raised to 90 ℃, and the mixture was allowed to react under reflux for 20 hours.
The external temperature was lowered to 50 ℃ and ethanol was removed by distillation under reduced pressure. 50mL of toluene was added to the resulting concentrated residue, and again distilled under reduced pressure. Vacuum drying was then carried out for 24 hours to obtain ammonium salt additive 3 of the following formula 3:
1H-NMR(DMSO-d6):4.94(broad，4H)，3.78(m，3H)，2.61(m，6H)，1.31(m，9H)
[ Synthesis example 4]
10g of triisopropanolamine was added to a 100mL round bottom flask, followed by 30mL of ethanol and stirring.
The mixture was cooled to 0 ℃ and 9.7g of methyl p-toluenesulfonate were gradually added. The temperature outside the flask was raised to 90 ℃, and the mixture was allowed to react under reflux for 24 hours.
The external temperature was lowered to 50 ℃ and ethanol was removed by distillation under reduced pressure. 50mL of acetone was added to the resulting concentrated residue and again distilled under reduced pressure. Vacuum drying was then carried out for 24 hours to obtain ammonium salt additive 4 of the following formula 4:
1H-NMR(DMSO-d6):7.48(d，2H)，7.12(d，2H)，5.05(broad，3H)，3.69(m，3H)，2.59(m，6H)，2.28(s，3H)，1.42(m，9H)
example 1
Preparing a substrate on a semiconductor wafer, wherein a thickness ofAnd deposited with a thickness ofA silicon nitride (SiN) film of (a).
As shown in table 1, 99.4 wt% of phosphoric acid having a concentration of 85%, 0.5 wt% of 3-aminopropylsilanetriol and 0.1 wt% of ammonium salt additive 1 were added and mixed to prepare an etching composition so that the total weight percentage was 100 wt%.
Example 2 to example 4
An etching composition was prepared using the same method as in example 1, except that: ammonium salt additives 2-4 were used.
Comparative example 1
An etching composition was prepared using the same method as in example 1, except that: no ammonium salt additive was used.
Comparative example 2
An etching composition was prepared using the same method as in example 1, except that: using ammonium acetate ((NH)4) OAc) as an ammonium salt additive.
< preparation of etching composition and measurement of selection ratio >
Each of the etching compositions obtained in example 1 to example 4 and comparative example 1 was added to a round-bottom flask, and heated for 60 minutes to be heated to 158 ℃. The silicon wafer was then immersed in the etching composition for 720 seconds and 6000 seconds to perform the etching process.
The surface of the silicon wafer on which the pattern was formed was selectively etched, and the thicknesses of the silicon oxide film and the silicon nitride film before and after the etching were measured using an ellipsometer (thin film thickness measuring instrument) (NANO VIEW, SEMG-1000). Based on this, the etching rate of the silicon oxide film (SiO E/R,) And the etching rate of the nitride film (SiN E/R,) The results are shown in Table 1, together with the selection ratio.
The selection ratio indicates a ratio of a nitride film etching rate to an oxide film etching rate, and the etching rate is a value calculated by dividing a film thickness difference before and after etching by an etching time (minute).
[ Table 1]
CE: comparative example EX: examples
As shown in table 1 above, it can be understood that very high etching selectivity ratio is exhibited when ammonium salt additives 1 to 4 are added as additives to the etching composition, as compared to comparative examples 1 and 2. Further, the etching compositions of examples 1 to 4 showed significantly superior effects in terms of silicon nitride etching rate (SiN E/R) compared to comparative examples 1 and 2. As a result, it was confirmed that an optimized etching composition for an etching process of a silicon nitride film can be provided.
Based on the results, it was confirmed that the use of the ammonium salt proposed in the present invention as an additive may result in improved structural stability based on active silicon. Accordingly, an etching composition having improved etching rate, selectivity and etching stability of a silicon nitride film can be provided.
[ Change of etching composition with time ]
The etching compositions of comparative example 1 and example 1 were stored at about 70 ℃ for a predetermined time, and etching tests were performed under the same conditions every 7 days. The results are shown in Table 2.
[ Table 2]
As shown in table 2 above, the etching composition of comparative example 1 showed a significantly reduced etching rate (SiN E/R) and a significantly reduced selectivity ratio after 21 days. However, the etching composition of example 1 to which the organic phosphoric acid additive 1 was added showed almost no change in etching rate (SiN E/R) and selectivity ratio. This shows that the etching composition according to the embodiment of the present invention has not only excellent etching rate and selectivity but also excellent storage stability, and thus can maintain excellent etching characteristics even when stored for a long time.
Such results also indicate that the structural stability effect of the ammonium salt additive 1 can maintain the function of inhibiting the etching of SiO without abnormal growth or decomposition of 3-aminopropylsilanetriol.
According to the foregoing example embodiments, the etching composition according to the present invention has a high etching selectivity ratio of a nitride film to an oxide film.
In addition, the use of the etching composition of the present invention can prevent the deterioration of film quality of an oxide film or the deterioration of electrical characteristics due to the etching of the oxide film when removing a nitride film, and can prevent the generation of particles, thereby improving device characteristics.
While exemplary embodiments have been shown and described above, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the scope of the invention as defined by the appended claims.