KR20190072412A - Composition for etching and manufacturing method of semiconductor device using the same - Google Patents

Abstract

The present invention relates to a silicon nitride film etching composition capable of selectively removing a nitride film while minimizing an etching rate of an oxide film, and to a production method of a semiconductor device using the same, wherein the silicon nitride film etching composition comprises phosphoric acid, metaphosphoric acid, an ammonium salt compound, and water.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for etching and a method for manufacturing a semiconductor device using the composition.

The present invention relates to an etching composition having a high selectivity, and a method for manufacturing the semiconductor device by applying the etching composition to an etching process.

In a semiconductor device, an oxide film such as a silicon oxide film (SiO ₂ ) and a nitride film such as a silicon nitride film (SiN _x ) are typical insulating films each having a structure in which one or more films are alternately laminated. The oxide film and the nitride film are 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, an etching composition in which phosphoric acid and deionized water are mixed is generally used. At this time, the deionized water is added to reduce the etching rate and prevent the change of the etching selectivity to the oxide film. However, there is a problem that the deionized water is defective due to a minute change in the amount of deionized water when the nitride film is removed by the wet etching process. Further, there is a limit in etching the nitride film to a required level due to a decrease in the etching selectivity ratio of the nitride film to the oxide film.

For example, in a device isolation process of a flash memory device, a nitride film and an oxide film are etched. The problems occurring at this time will be described in detail with reference to the drawings.

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 then a polysilicon film 12, The oxide film 13 and the pad nitride film 14 are selectively etched to form a trench. Subsequently, a SOD (Spin on Dielectric) oxide film 15 is formed until the trench is gapfilled, and the CMP process is performed on the SOD oxide film 15 using the pad nitride film 14 as a polishing stop film.

Next, referring to FIG. 2, a wet etching process is performed on the etching composition containing phosphoric acid to remove the pad nitride film 14, followed by a cleaning process to remove the buffer oxide film 13. Through such a process, a device isolation film 15A is formed in the field region.

However, when a composition for etching containing phosphoric acid is used in the wet etching process for removing the pad nitride film 14, since the etch selectivity of the nitride film with respect to the oxide film is lowered, So that it becomes difficult to control the effective field oxide height (EFH). This can not ensure a sufficient wet etching time for removing the nitride film, or an additional process is required to lower the etching efficiency and cause a change, which may adversely affect the characteristics of the device.

(HF) or nitric acid (HNO ₃ ) is added to the phosphoric acid in order to improve the etch selectivity of the phosphoric acid-containing etching composition. However, this results in the effect of inhibiting the etch selectivity of the nitride film and the oxide film Respectively. In addition, although a composition for etching having phosphoric acid added with silicate or silicate has been disclosed, there is a problem that particles are generated on the substrate by the silicate or silicic acid, thereby lowering the reliability of the semiconductor device.

Therefore, there is a need for a composition for etching a high selectivity ratio that does not cause generation of particles while selectively etching a nitride film with respect to an oxide film.

Korean Patent Publication No. 2013-0042273 (Publication date: March 26, 2014)

Disclosed is a composition for etching a silicon nitride film having a high selectivity ratio which can selectively remove a nitride film while minimizing an etching rate of an oxide film and does not cause generation of particles which adversely affect the characteristics of a semiconductor device.

The present invention also provides a method of manufacturing a semiconductor device using the etching composition.

In order to solve the above problems, the present invention provides a composition for etching a silicon nitride film comprising phosphoric acid, metaphosphoric acid, an ammonium salt compound and water.

Further, the present invention provides a method of manufacturing a semiconductor device comprising etching the insulating film with the etching composition.

The etching composition of the present invention has a high etch selectivity to a nitride film for an oxide film, so that the effective oxide film height (EFH) can be easily controlled by adjusting the etching rate of the oxide film. In addition, the etching composition of the present invention can prevent damage to the oxide film due to the removal of the nitride film, deterioration of electrical characteristics due to etching of the oxide film, generation of particles, and the like, and reliability of the semiconductor device can be improved.

Therefore, the etching composition of the present invention can be applied to a manufacturing process of a semiconductor device (for example, a device isolation process of a flash memory device, a process of forming a pipe channel of a 3D flash memory device, , A process of forming a diode in a phase change memory, etc.), thereby contributing to an improvement in the efficiency of the manufacturing process of the semiconductor device.

1 and 2 are process cross-sectional views for explaining a device isolation process of a conventional flash memory device.
3 to 5 are cross-sectional views illustrating a device isolation process of a flash memory device including an etching process using an etching composition according to an example of the present invention.
6 to 11 are cross-sectional views illustrating a process of forming a pipe channel of a flash memory device including an etching process using an etching composition according to another embodiment of the present invention.
12 and 13 are cross-sectional views illustrating a process of forming a diode in a phase-change memory including an etching process using an etching composition according to another example of the present invention.

When a composition for general phosphoric acid etching is used for wet etching of a silicon nitride film, an etching composition containing metaphosphoric acid and phosphoric acid is used in consideration of the problem that the etching rate is lowered as the etching process proceeds. This has been an attempt to maintain a constant etch rate while continuously supplying phosphoric acid in the etching composition, thereby enabling a uniform and selective etch in the entire silicon nitride film.

However, when preparing a composition for etching by directly introducing meta-phosphoric acid in the form of solid or powder into phosphoric acid, a high temperature and a long manufacturing time are required to dissolve meta-phosphoric acid.

Accordingly, the present invention can solve such a problem by including an ammonium salt compound in an etching composition containing phosphoric acid and metaphosphoric acid.

Hereinafter, the present invention will be described in detail.

1. Silicon nitride film etching composition

The composition for etching a silicon nitride film of the present invention (hereinafter referred to as "composition for etching") includes phosphoric acid, metaphosphoric acid, an ammonium salt compound, and water.

The phosphoric acid reacts with silicon nitride to etch the nitride. As shown in Reaction Scheme 1 below, the silicon nitride can be etched by reacting with phosphoric acid.

[Reaction Scheme 1]

3Si ₃ N ₄ + 27H ₂ O + 4H ₃ PO ₄ → 4 (NH ₄ ) ₃ PO ₄ + 9SiO ₂ H ₂ O

The phosphoric acid content may be 50 to 90 parts by weight, preferably 80 to 85 parts by weight, based on the total weight of the composition for etching. If the content of the phosphoric acid is less than 70 parts by weight, the etching ability of the silicon nitride of the composition may be deteriorated. If the amount exceeds 95 parts by weight, the silicon nitride may over-crystallize and it may be difficult to obtain the required etching profile.

Metaphosphoric acid is a compound having the structure of HPO ₃ , which has a lower solubility in water than water and has a function of stably etching nitride since it is gradually converted from metaphosphoric acid to phosphoric acid in water.

The content of metaphosphoric acid may be 0.01 to 10 parts by weight, preferably 5 to 7 parts by weight, based on the total weight of the composition for etching. If the content of metaphosphoric acid is less than 0.01 part by weight, the desired profile can not be obtained due to the high selectivity of the silicon oxide film due to the high etching rate. If the content exceeds 10 parts by weight, etching of the silicon oxide film is hardly performed, Can also be reduced.

The ammonium salt compound is basic, and when metaphosphoric acid is dissolved in the ammonium salt compound-containing aqueous solvent, dissolution of metaphosphoric acid is performed due to its high solubility, and when it is mixed with phosphoric acid, the production time is shortened, have. Specifically, the composition comprises the steps of: preparing a mixture comprising metaphosphoric acid, an ammonium salt compound and water; And mixing the mixture and phosphoric acid.

Such an ammonium salt compound is not particularly limited but includes at least one selected from the group consisting of NH ₄ ⁺ , a primary ammonium ion, a secondary ammonium ion, a tertiary ammonium ion and a quaternary ammonium ion as cations desirable.

The ammonium salt compound is a weak base suitable for the phosphoric acid process, and may not be thermally stable and bubbled due to process characteristics heated at a high temperature. Specifically, the ammonium salt compound is selected from the group consisting of ammonium acetate, ammonium nitrate, ammonium phosphate, tetramethyl ammonium hydroxide (TMAH), and tetraethyl ammonium hydroxide (TEAH) Or more species.

Such an ammonium salt compound and metaphosphoric acid may be contained in a molar ratio of 0.1 to 2: 1 to 5, specifically 0.5 to 1: 2 to 4. When the metaphosphoric acid is contained below the lower limit, the solubility of metaphosphoric acid is low, so that the stabilization time can be prolonged when mixed in the phosphoric acid. When the metaphosphoric acid is contained in excess of the upper limit value, The etching rate of the silicon nitride film can be inhibited.

The composition for etching includes water as a solvent. For example, the etching composition may comprise residual water. Specifically, the etching composition may contain 50 to 90% by weight of phosphoric acid, 0.01 to 10% by weight of metaphosphoric acid, 0.001 to 5% by weight of an ammonium salt compound, and 5 to 40% by weight of water.

The etching composition may have a nitride film etching rate of 50 to 80 Å / min and an oxide film etching rate of 0.00 to 3.00 Å / min. Specifically, the etching composition may have a nitride film etching rate of 60 to 70 Å / min and an oxide film etching rate of 0.01 to 1 Å / min.

Further, the etching composition may have a ratio of the nitride film etching rate / the oxide film etching rate of 50 or more. Specifically, the etching composition may have a ratio of a nitride film etching rate / an oxide film etching rate of 100 or more, 50 to 10,000, 100 to 8,000, 100 to 3,000, or 100 to 2,000. When the ratio of the etching rate of the nitride film / the etching rate of the oxide film is within the above range, the nitride film can be selectively removed while minimizing the etching rate of the oxide film, and the etching selectivity of the nitride film to the oxide film is high, (EFH) can be easily controlled.

2. Manufacturing Method of Semiconductor Device

The present invention provides a method for manufacturing a semiconductor device using the etching composition described above. Specifically, the method for fabricating a semiconductor device according to the present invention includes a step of etching the insulating film with the etching composition described above. More specifically, the etching composition can selectively etch the insulating film in a structure in which the insulating film and the oxide film are mixed.

Further, the insulating film may be a nitride film.

The nitride film may be a silicon nitride film (for example, a SiN film, a SiON film, or the like).

The oxide film may be a silicon oxide film (for example, an SOD (Spin On Dielectric) film, a HDP (High Density Plasma) film, a thermal oxide film, a BPSG (Borophosphate Silicate Glass) film, a PSG (Polysilazane) film, FSG (Fluorinated Silicate Glass) film, LP-TEOS (Low Pressure Tetra Ethyl Ortho Silicate) film, PETEOS (Plasma Enhanced Tetra Ethyl Ortho Silicate) ), An MTD (Medium Temperature Oxide) film, an USP (Undoped Silicate Glass) film, an SOG (Spin On Glass) film, an APL (Advanced Planarization Layer) film, an ALD (Atomic Layer Deposition) film, a PE- ), O3-TEOS (O3-Tetra Ethyl Ortho Silicate) film, or the like).

The method of etching the nitride film is not particularly limited, but may be wet etching (for example, a method of dipping or a method of spraying).

The etching temperature at which the nitride film is etched is not particularly limited, and may be determined in consideration of other processes and other factors. Specifically, the etching temperature may be 50 to 300 ° C, and more specifically, 100 to 200 ° C.

The method for manufacturing a semiconductor device according to the present invention is a method for manufacturing a semiconductor device through a process of selectively etching a nitride film with the above composition for etching. Therefore, particle generation due to self-bonding and reaction of silicon ions, It is possible to provide a semiconductor device having excellent reliability while ensuring process stability.

For example, a case where the above-described composition for etching is used in a device isolation process of a flash memory device among semiconductor devices will be described in detail with reference to the drawings.

Referring to FIG. 3, a tunnel oxide film 21, a polysilicon film 22, a buffer oxide film 23, and a pad nitride film 24 may be formed in this order on a substrate 20. Subsequently, the pad nitride film 24, the buffer oxide film 23, the polysilicon film 22 and the tunnel oxide film 21 are selectively etched to expose the element isolation regions of the substrate 20 through the photo and etching processes . Subsequently, the exposed substrate 20 may be selectively etched using the pad nitride film 24 as a mask to form the trench 25 having a predetermined depth from the surface.

Referring to FIG. 4, the oxide film 26 may be formed on the entire surface of the substrate 20 by chemical vapor deposition (CVD) or the like until the trench 25 is formed. Then, the oxide film 26 may be subjected to a chemical mechanical polishing (CMP) process using the pad nitride film 24 as a polishing stop film. Then, a cleaning process can be performed using dry etching.

Referring to FIG. 5, the buffer oxide film 23 may be removed by selectively removing the pad nitride film 24 by a wet etching process using the etching composition according to the present invention, and then performing a cleaning process. Thus, the element isolation film 26A is formed in the field region. By using the above etching composition having a high etching selectivity to the oxide film, the nitride film can be selectively and completely removed for a sufficient time while minimizing the etching of the oxide film that is gapped in the shallow trench isolation (STI) have. Accordingly, the effective oxide film height (EFH) can be easily controlled, and the oxide film damage or the electrical property degradation due to etching and the generation of particles can be prevented, and the characteristics of the semiconductor device can be improved.

Although the above example has been described for the flash memory device, the composition for etching the high selectivity of the present invention can also be used for the device isolation process of the DRAM device.

As another example, a case where the above-described etching composition is used in a channel forming process of a flash memory device among semiconductor devices will be described with reference to the drawings.

Referring to FIG. 6, a pipe gate electrode film 31 in which a nitride film 32 for forming a pipe channel is buried may be formed on a substrate 30. The first and second conductive films 31A and 31B constituting the pipe gate electrode film 31 may include, for example, impurity-doped polysilicon. Specifically, a first conductive film 31A is formed on the substrate 30, a nitride film is deposited on the first conductive film 31A, and the nitride film is patterned to form a nitride film 32 for forming a pipe channel The second conductive film 31B can be formed on the first conductive film 31A exposed by the nitride film 32. [ The first and second conductive films 31A and 31B can form the pipe gate electrode film 31. [

Then, the first interlayer insulating film 33 and the first gate electrode film 34 may be alternately stacked to form a plurality of memory cells stacked in the vertical direction on the process result. Hereinafter, for convenience of explanation, a structure in which the first interlayer insulating film 33 and the first gate electrode film 34 are alternately stacked is referred to as a cell gate structure CGS. Here, the first interlayer insulating film 33 is for isolating a plurality of memory cells, and may include, for example, an oxide film. The first gate electrode film 34 may be formed of, for example, Silicon. Here, the first gate electrode layer 34 of six layers is illustrated in FIG. 6, but the present invention is not limited thereto.

Next, a pair of first and second holes H1 and H2 for exposing the nitride film 32 can be formed by selectively etching the cell gate structure CGS. The first and second holes H1 and H2 may be spaces for channel formation of a memory cell.

Referring to FIG. 7, a nitride film 35 buried in the first and second holes H1 and H2 may be formed. This nitride film 35 prevents damages that may occur when the first gate electrode film 34 is exposed by the first and second holes H1 and H2 in a trench forming process (see FIG. 8) .

Referring to FIG. 8, a plurality of first gate electrode layers 34 are formed on the first and second holes H1 and H2 so as to be separated by the first and second holes H1 and H2. The trench S can be formed by selectively etching the structure CGS.

Referring to FIG. 9, a sacrificial layer 36 buried in the trench S may be formed.

Referring to FIG. 10, a second interlayer insulating film 37, a second gate electrode film 38, and a second interlayer insulating film 37 may be sequentially formed on the resultant process to form a selection transistor. Hereinafter, for convenience of explanation, the stacked structure of the second interlayer insulating film 37, the second gate electrode film 38 and the second interlayer insulating film 37 is referred to as a select gate structure SGS. The second interlayer insulating film 37 may include, for example, an oxide film, and the second gate electrode film 38 may include, for example, impurity-doped polysilicon.

Subsequently, the selective gate structure SGS is selectively etched to form third and fourth holes H3 and H4 for exposing the nitride film 35 buried in the pair of first and second holes H1 and H2. do. The third and fourth holes H3 and H4 are regions in which the channel of the selection transistor is to be formed.

11, the nitride film 35 exposed by the third and fourth holes H3 and H4 and the nitride film 32 thereunder are selectively removed by a wet etching process using the etching composition according to the present invention. can do. As a result of this process, a pair of cell channel holes (H5 and H6) in which the channel film of the memory cell is to be formed and a pipe channel hole (H7) disposed under the cell channel holes (H5 and H6) have. As described above, by using the composition for etching of high selectivity of the present invention, the nitride film can be completely and selectively removed for a sufficient time without loss of the oxide film, and the pipe channel can be accurately formed without loss of the profile. In addition, it is possible to prevent the generation of particles, which has been a problem in the prior art, and to secure the stability and reliability of the process.

Thereafter, a flash memory device can be formed by performing a subsequent process, for example, a floating gate forming process and a control gate forming process.

As another example, a case where the above-described composition for etching is used in the process of forming a diode in a phase-change memory device of a semiconductor device will be described with reference to the drawings.

Referring to FIG. 12, an insulating structure is provided having an opening exposing a conductive region 41 on a substrate 40. The conductive region 41 may be, for example, an n + impurity region. Subsequently, after the polysilicon film 42 is formed so that the openings are partly buried, a diode can be formed by ion implantation of impurities. Then, a titanium silicide film 43 may be formed on the polysilicon film 42. The titanium silicide film 43 may be formed by forming a titanium film and then heat-treating the titanium silicide film 43 to react with the polysilicon film 42. Then, the titanium nitride film 44 and the nitride film 45 can be sequentially formed on the titanium silicide film 43. Next, an oxide film 46 may be formed in an isolated space between the diodes formed by performing a dry etching process using a hard mask, and then a CMP process may be performed to form the primary structure of the separated lower electrode.

Referring to FIG. 13, the upper nitride layer 45 may be selectively removed by performing a wet etching process using the etching composition according to the present invention. By using the composition for etching the high selectivity ratio of the present invention at the time of removing the nitride film as described above, the nitride film can be selectively and completely removed for a sufficient time without loss of the oxide film. In addition, it is possible to prevent the deterioration of the electrical characteristics and the generation of particles due to damage of the oxide film or the etching of the oxide film, thereby improving the characteristics of the semiconductor device.

Then, titanium may be deposited in the space where the nitride film 45 is removed to form the lower electrode.

Hereinafter, the present invention will be described in detail with reference to examples. However, the following examples are illustrative of the present invention, and the present invention is not limited by the following examples.

[Example]

Examples 1 to 7. Etching compositions

Specifically, an ammonium salt compound and metaphosphoric acid were stirred and sufficiently dissolved, and the resulting mixture was added to phosphoric acid to prepare an etching composition.

Component (% by weight) Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Phosphoric acid 75 65 92 85 75 80 83 Metaphosphoric acid 7 5 5 0.005 10 6 6 Ammonium salt compound Ammonium phosphate - One - 0.005 - 2 0.1 Ammonium chloride - - One - One - - TMAH One - - - - - - water 17 29 2 14.99 14 12 10.9 Total (% by weight) 100 100 100 100 100 100 100

Comparative Examples 1 to 3.

The composition for etching having the composition shown in the following Table 2 was prepared in the same manner as in Example 1.

ingredient Comparative Example 1 Comparative Example 2 Comparative Example 3 Phosphoric acid 75 80 85 Metaphosphoric acid 7 5 - Ammonium salt compound Ammonium phosphate - - - Ammonium chloride - - 0.5 TMAH - - - Carboxylic acid One - - water 17 15 14.5 Total (% by weight) 100 100 100

Experimental Example 1. Selection ratio measurement

The nitride and oxide films were etched at 165 ° C. using the compositions for etching of Examples 1 to 7 and Comparative Examples 1 to 3, and the film thickness was measured using an ellipsometer (NANO VIEW, SEMG-1000) The etch rates for the nitride and oxide films were measured and are shown in Table 3 below.

Specifically, the etching rate in Table 3 is calculated by dividing the film thickness before etching treatment of each film by the etching time (minutes) after etching each film for 300 seconds and the difference in film thickness after etching treatment.

division Nitride film etching rate (Å / min) The oxide etch rate (Å / min) Nitride film etching rate / oxide film etching rate Example 1 65.14 0.12 542.8 Example 2 43.78 0.03 1459.3 Example 3 87.56 0.75 116.7 Example 4 72.61 1.52 47.77 Example 5 64.61 0.01 6461 Example 6 66.01 0.2 330.1 Example 7 65.56 1.23 53.3 Comparative Example 1 72.07 2.03 35.5 Comparative Example 2 70.86 2.25 31.5 Comparative Example 3 71.5 2.2 32.5

Referring to Table 3, it can be seen that the etching compositions of Examples 1 to 7 are significantly higher in etching rate of the nitride film than those of the etching compositions of Comparative Examples 1 to 3. This can be seen as supporting that the etching composition of the present invention selectively etches the nitride film.

20, 30, 40: substrate 21: tunnel oxide film
22: polysilicon film 23: buffer oxide film
24: pad nitride film 25: trench
26: oxide film 26A: element isolation film
31: pipe gate electrode film 32, 35: nitride film
36: sacrificial layer 33: first interlayer insulating film
34: first gate electrode film 37: second interlayer insulating film
38: second gate electrode film 41: conductive region
42: polysilicon film 43: titanium silicide film
44: titanium nitride film 45: nitride film
46: oxide film

Claims (9)

Phosphoric acid, metaphosphoric acid, an ammonium salt-based compound, and water. The method according to claim 1,
Wherein the ammonium salt compound comprises at least one selected from the group consisting of NH ₄ ⁺ , a primary ammonium ion, a secondary ammonium ion, a tertiary ammonium ion, and a quaternary ammonium ion as cations. The method of claim 2,
The ammonium salt compound may be at least one selected from the group consisting of ammonium acetate, ammonium nitrate, ammonium phosphate, tetramethyl ammonium hydroxide (TMAH), and tetraethyl ammonium hydroxide (TEAH) By weight based on the total weight of the composition. The method according to claim 1,
Wherein the composition comprises 50 to 90 parts by weight of phosphoric acid and 0.01 to 10 parts by weight of metaphosphoric acid. The method according to claim 1,
Wherein the composition comprises an ammonium salt compound and metaphosphoric acid in a molar ratio of 0.1: 2: 1 to 5: 1. The method according to claim 1,
Said composition comprising the steps of: preparing a mixture comprising metaphosphoric acid, an ammonium salt based compound and water; And mixing the mixture and phosphoric acid. The composition for etching a silicon nitride film according to claim 1, The method according to claim 1,
Wherein the composition for etching has a ratio of a nitride film etching rate / an oxide film etching rate of 50 or more. A method for manufacturing a semiconductor device, comprising etching an insulating film with the composition for etching according to any one of claims 1 to 7. The method of claim 8,
Wherein the insulating film is a nitride film.

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