CN119020117B

CN119020117B - Composition and method for removing residues after ashing of semiconductor substrate

Info

Publication number: CN119020117B
Application number: CN202411120991.7A
Authority: CN
Inventors: 詹博筌; 王秋桂; 尤绍峰
Original assignee: Xinshida Electronic Materials Kunshan Co ltd
Current assignee: Xinshida Electronic Materials Kunshan Co ltd
Priority date: 2024-08-15
Filing date: 2024-08-15
Publication date: 2025-08-29
Anticipated expiration: 2044-08-15
Also published as: CN119020117A

Abstract

The present invention discloses a composition and method for removing residues after ashing of semiconductor substrates. The composition comprises, by weight, 0.05-10 wt% of an organic amine compound, 0.001-10 wt% of a wetting agent, and 80-99.5 wt% of water, wherein the wetting agent comprises at least one of a polyol compound and a surfactant. The composition is hydroxylamine-free and fluoride-free, and is primarily composed of an organic amine compound, a wetting agent (a polyol compound and/or a surfactant), and water to form a water-based cleaning agent. The composition does not contain a large amount of organic solvents, chelating agents, or silicate corrosion inhibitors, resulting in lower costs and environmental friendliness. The composition operates at low temperatures, preventing the loss of water and active ingredients in the cleaning agent. The composition exhibits good stability, a low metal erosion rate, and stable cleaning performance. The composition effectively removes residues after dry etching plasma ashing, while exhibiting minimal or no erosion of metal circuits, dielectric layers, and substrate materials on the original wafer.

Description

Composition and method for removing post-ashing residue from semiconductor substrates

Technical Field

The invention belongs to the technical field of semiconductor cleaning, and particularly relates to a composition and a method for removing residues after ashing of a semiconductor substrate.

Background

In the manufacture of semiconductor integrated circuits, it is necessary to form fine electronic circuit patterns on a substrate using photolithography techniques (coating of photoresist layers, exposure, development, and etching). During the patterning process, residues remain on the surface of the semiconductor substrate, and etching residues need to be removed or cleaned before the patterning process is performed in the next step, and such removal or cleaning is commonly referred to as "post-etch residue" removal or "post-ash residue" removal in the industry. These residues can adversely affect the electrical performance of the semiconductor by causing shorts between the wires or causing poor adhesion during metal or dielectric layer deposition in subsequent processes. It is therefore necessary to thoroughly remove or clean these residues, which may lead to degradation of electrical performance, reliability, etc. of the semiconductor device if the removal or cleaning is not complete.

Wet cleaning is commonly used in the industry to remove or clean post ash residue. The existing traditional cleaning agents mainly comprise hydroxylamine, fluorine and semi-water-based amine (without hydroxylamine) and water-based cleaning agents.

Hydroxylamine cleaning solution has good cleaning effect, and hydroxylamine salt are important chemical raw materials, so that the hydroxylamine cleaning solution is widely applied to the fields of semiconductor cleaning and the like. Hydroxylamine, on the one hand, is less stable and is prone to explosion at higher operating temperatures. This results in a relatively high safety risk for the hydroxylamine type cleaning solution during its formulation and use.

The fluorine-based cleaning agent generally comprises fluoride, amine compounds, organic solvents and water, can be cleaned at a lower temperature (room temperature to 50 ℃), but has the defects that the corrosion of a base material cannot be well controlled, fluoride such as ammonium fluoride or hydrofluoric acid has great harm to a human body in an acidic environment, direct contact is toxic, no immediate treatment can cause bone erosion, long-time inhalation can cause osteoporosis of the human body, and great safety risks exist.

Semi-aqueous amine cleaners are mainly organic amines and organic stripping solvents, water and metal corrosion inhibitors, but such cleaners generally operate at relatively high temperatures (50-90 ℃) and have poor removal of inorganic metal residues and are not widely used.

While water-based cleaning solutions are mainly composed of metal ion-free bases, silicate corrosion inhibitors, oxometallates, chelating agents and water, operate at low temperatures and are environmentally friendly. However, the existing water-based cleaning agent has some defects, such as silicate corrosion inhibitor increases viscosity of the cleaning agent to be unfavorable for cleaning of fine line width or tiny holes on a chip structure, and the chemical bonding generated by the silicate corrosion inhibitor during the cleaning process may cause discoloration and pollution of some substrates. At the same time, as the pH decreases, particles are generated by hydrolysis and contaminate the wafer. The present invention is derived therefrom.

Disclosure of Invention

In view of at least one of the above problems, it is an object of the present invention to provide a composition and a method for removing post-ashing residues from semiconductor substrates, wherein the composition is free of fluoride and hydroxylamine, and is capable of effectively removing post-dry etch plasma ashing residues at a relatively low temperature (below 50 ℃), without or with very low erosion of metal lines, dielectric layers and wafer substrate materials on the original wafer.

The technical scheme of the invention is as follows:

One of the objects of the present invention is to provide a composition for removing residues after ashing of a semiconductor substrate, which comprises, in weight percent, 0.05 to 10wt% of an organic amine compound, 0.001 to 10wt% of a wetting agent comprising at least one of a polyol compound or a surfactant, and 80 to 99.5wt% of water.

Preferably, the organic amine compound comprises at least one of N-methylethanolamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, 2- (2-aminoethoxy) ethanol, N-ethylethanolamine, N-dimethylethanolamine, N-diethylethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, cyclohexylamine diethanol, quaternary amine hydroxide.

Preferably, the quaternary amine hydroxide comprises at least one of tetramethylammonium hydroxide and tetraethylammonium hydroxide.

Preferably, the polyol compound includes at least one of ethylene glycol, propylene glycol, glycerol, polyethylene glycol, and polypropylene glycol.

Preferably, 0.1 to 10wt% of a phenolic corrosion inhibitor is also included.

Preferably, the phenolic corrosion inhibitor comprises at least one of tertiary butyl catechol, resorcinol, 2, 3-dihydroxybenzoic acid, gallic acid.

Preferably, it has a pH of 10 to 12.

Preferably, the operating temperature thereof is from 10 to 50 ℃.

It is an object of the present invention to provide a method for removing post-ashing residues from a semiconductor substrate by contacting the surface of the semiconductor substrate from which the post-ashing residues are to be removed with a composition as described in any one of the above.

Preferably, the temperature of the composition is 10-50 ℃ when the composition is contacted with the surface of the semiconductor substrate.

Compared with the prior art, the invention has the advantages that:

The composition and the method for removing the residues after the ashing of the semiconductor substrate, disclosed by the invention, do not contain hydroxylamine, can solve the potential safety hazard problem caused by easy explosion of the hydroxylamine, do not contain fluoride, and can solve the safety risk problem of the fluoride. The water-based cleaning agent is formed by taking the organic amine compound as a main body and matching with a wetting agent (a polyol compound and/or a surfactant) and water, does not contain a large amount of organic solvents, does not contain chelating agents and silicate corrosion inhibitors, and has lower cost and environmental friendliness. The cleaning agent is operated at a low temperature (10-50 ℃), the moisture and the active ingredients in the cleaning agent are not easy to lose, the stability of the composition is better, the corrosion rate to metal is lower, the cleaning efficiency is stable, residues after dry etching plasma ashing can be effectively removed, and the metal circuit, the dielectric layer and the wafer substrate material on the original wafer are not corroded or are corroded very little.

Drawings

The invention is further described below with reference to the accompanying drawings and examples:

FIG. 1 is a graph showing the erosion rate of aluminum at various temperatures for a composition for removing residues after ashing of a semiconductor substrate according to example 1 of the present invention;

FIG. 2 is an electron micrograph of a semiconductor structure of SRO/TEOS/SiN prior to cleaning using the composition for removing residues after ashing of a semiconductor substrate of example 11 of the present invention;

FIG. 3 is an electron micrograph of a semiconductor structure cleaned of SRO/TEOS/SiN using the composition for removing residues after ashing of a semiconductor substrate according to example 11 of the invention;

FIG. 4 is an electron micrograph of a TiW/Al semiconductor structure prior to cleaning using the composition of example 11 of the present invention for removing residues after ashing of a semiconductor substrate;

FIG. 5 is an electron micrograph of a TiW/Al semiconductor structure cleaned using the composition of example 11 of the present invention for removing residues after ashing.

Detailed Description

The objects, technical solutions and advantages of the present invention will become more apparent by the following detailed description of the present invention with reference to the accompanying drawings. It should be understood that the description is only illustrative and is not intended to limit the scope of the invention. In addition, in the following description, descriptions of well-known structures and techniques are omitted so as not to unnecessarily obscure the present invention.

The composition for removing residues after ashing of the semiconductor substrate comprises, by weight, 0.05-10wt% of an organic amine compound, 0.001-10wt% of a wetting agent and 80-99.5wt% of water, wherein the wetting agent comprises at least one of a polyalcohol compound or a surfactant, does not contain hydroxylamine, does not contain fluoride, does not contain a large amount of an organic solvent, and does not contain an organic carboxylic acid chelating agent and a silicate corrosion inhibitor. The above mentioned component reagents are all commercially available or well known to those skilled in the art.

According to some preferred embodiments of the present invention, the organic amine compound preferably comprises at least one of N-methylethanolamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, 2- (2-aminoethoxy) ethanol, N-ethylethanolamine, N-dimethylethanolamine, N-diethylethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, cyclohexylamine diethanol, quaternary amine hydroxides. The specific organic amine compounds mentioned above are all commercially available or well known chemical agents to those skilled in the art. Further preferably, the quaternary amine hydroxide comprises at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide.

According to some preferred embodiments of the present invention, the polyol compound comprises at least one of ethylene glycol, propylene glycol, glycerol, polyethylene glycol, polypropylene glycol. The specific polyol compounds mentioned above are all commercially available or well known to those skilled in the art. The surfactant is a compound which is commonly used in the market, such as soap solution, shampoo and the like and contains hydrophilic groups and lipophilic groups in the molecule, and exemplary surfactants Triton X-100 (polyethylene glycol octyl phenyl ether) are used in some embodiments of the invention. When the wetting agent is a combination of a polyol compound and a surfactant, the specific ratio of the two is not particularly limited, and may be selected to be 1:1.

According to some preferred embodiments of the present invention, phenolic corrosion inhibitors may also be added to the composition in combination, rather than silicate-based corrosion inhibitors of the prior art. The addition of the phenolic corrosion inhibitor can further improve the protection of aluminum and copper materials, namely further reduce the corrosion of the aluminum and copper materials. Preferably, the phenolic corrosion inhibitor is present in the formulation in an amount of 0.1 to 10wt%. The embodiment of the invention optimally controls the content of the phenolic corrosion inhibitor, improves the protectiveness and does not greatly influence the pH value of the formula. Illustratively, the phenolic corrosion inhibitor of an embodiment of the present invention is selected from at least one of tributylcatechol, catechol, resorcinol, 2, 3-dihydroxybenzoic acid, gallic acid. The specific phenolic corrosion inhibitors mentioned above are all commercially available or well known chemical agents to those skilled in the art.

According to some preferred embodiments of the invention, the composition has a pH of 10-12. Because the organic amine compound is used as a main body in the formula, the composition is alkaline, the pH value of the formula is between 10 and 12 by optimizing the formula and controlling the dosage of the wetting agent and water, compared with the existing acidic cleaning agent, the corrosion to wires such as aluminum, copper and the like is smaller, and the composition can not corrode or have extremely low corrosion to metal circuits, dielectric layers and wafer substrate materials on the original wafer by controlling the pH value.

According to some preferred embodiments of the invention, the operating temperature of the composition is from 10 to 50 ℃. Because the composition of the embodiment of the invention is a water-based cleaning agent, the water ratio is very large, and the water and active ingredients in the cleaning agent can be reduced from being scattered by low-temperature operation, so that the composition has higher stability and extremely high cleaning energy efficiency. Compared with the existing cleaning agents such as DuPont EKC-270 and the like which are required to be operated at the temperature of 60-80 ℃, the composition provided by the embodiment of the invention has the advantages of milder operation temperature and lower energy consumption.

The applicant found that the composition of the present invention has a fast reaction rate and high removal efficiency (30-300 seconds) when used for removing residues after ashing semiconductor substrates, and is not suitable for conventional slot-type machine operation, because the time difference exists when all the chip hangers are pulled away, and thus the difference among the chips is caused. The composition provided by the embodiment of the invention can exert the greatest benefit, thereby greatly improving the production efficiency and reducing the production period and the production cost.

The advantages and rationality of the compositions of the invention are illustrated below in connection with the specific examples, which are presented in tables 1-4.

Table 1 formulation of the compositions of examples 1 to 20 and aluminum erosion rates at 25 ℃ operating temperature

Note that "-" in the table indicates that polyethylene glycol-200 has an average molecular weight of 200g/mol with or without addition.

Table 1 is an example of a formulation employing a composition of an example of the present invention. From the results of the aluminum etch rate measurements of examples 1 to 7 in table 1 above, it is seen that the aluminum etch rate is significantly lower when the composition comprising monoethanolamine alone is used for semiconductor substrate cleaning than when the composition comprising tetramethylammonium hydroxide alone is used for semiconductor substrate cleaning (examples 1 and 5). The compositions using a mixture of monoethanolamine and tetramethylammonium hydroxide as the organic amine compounds (examples 2 to 4 and examples 6 and 7) showed significantly lower aluminum attack rates than tetramethylammonium hydroxide and decreased attack rates as the ratio of monoethanolamine to tetramethylammonium hydroxide increased, and when a certain ratio was reached (5:1 for example 7 of the present invention, lower than example 1, and 2:1 for example 6, higher than example 1) were seen. Therefore, the applicant can ensure extremely high cleaning energy efficiency and lower cost by optimizing the dosage of the organic amine compound to be 0.05-10wt%.

Examples 8 to 13 are examples in which different types of polyol compounds were added based on example 6 (wherein example 8 to example 11 each had one polyol compound added, example 12 had one surfactant added, and example 13 had one polyol compound and one surfactant added at the same time), and as a result of the aluminum corrosion rate test, the composition added with the polyol compound had a lower aluminum corrosion rate than the composition without the polyol compound (i.e., examples 1 to 7), and the composition added with the polyol compound and the surfactant at the same time had a significantly lower aluminum corrosion rate than the polyol compound alone, indicating that the addition of the wetting agent could lower the aluminum corrosion rate and the compounding of the polyol compound with the surfactant could further lower the aluminum corrosion rate.

From examples 14 to 16, it is understood that the aluminum corrosion rate gradually decreases with increasing amount of the polyol compound, but the magnitude of the decrease is lower. Therefore, the applicant can ensure extremely high cleaning energy efficiency by optimizing the using amount of the wetting agent to be 0.001-10wt% and can also enable the cost to be lower.

From examples 17 to 20, it is clear that examples 17 to 20 are compositions in which different phenolic corrosion inhibitors are added based on example 11, and from the results of the corrosion rate detection of aluminum, the addition of the phenolic corrosion inhibitor can further slow the corrosion rate of aluminum without affecting the cleaning effect. Therefore, the applicant can ensure extremely high cleaning energy efficiency and low cost by optimizing the dosage of the optimal phenolic corrosion inhibitor to be 0.1-10wt%.

Table 2 the compositions of examples 1 to 20 were used for cleaning duration (temperature 25 ℃ C., units: seconds) for removing residues of various materials after plasma ashing

	Aluminum (Al)	Silicon nitride	Titanium nitride
				Example 1	30	120	180
Example 2	15	60	90
				Example 3	<15	60	90
Example 4	<15	30	60
				Example 5	<15	30	60
Example 6	15	90	120
				Example 7	30	120	180
Example 8	45	180	240
				Example 9	30	120	180
Example 10	60	240	300
				Example 11	45	180	240
Example 12	180	360	>600
				Example 13	180	300	>600
Example 14	45	180	240
				Example 15	60	210	300
Example 16	90	240	360
				Example 17	60	180	240
Example 18	90	240	300
				Example 19	60	180	240
Example 20	90	240	300

As can be seen from Table 2, the compositions of the present invention have a residual removal time of less than 600 seconds after ashing of semiconductor plasma for removing various materials, and in particular, a time of less than 60 seconds for aluminum materials, a short time, and a fast reaction rate.

Table 3 erosion rates (units) for different metals for the compositions of examples 8 to 1325°C)

In order to verify the reliability of the compositions of the examples of the present invention, as shown in Table 3, the applicant has also verified the erosion rates of the compositions of examples 8 to 13 for different metals, and as can be seen from Table 3, the compositions of examples 8 to 13 have very little erosion of metals such as aluminum, copper, silicon oxide films made of electronic grade tetraethyl orthosilicate (TEOS), low-K insulating materials, silicon nitride, titanium nitride, and silicon oxide films made at high temperature (Thermal oxide). It was thus verified that the composition of the formulation of the present invention can be used for cleaning and removal of residues after ashing of semiconductor substrates.

Further, to further verify the optimum operating temperature of the compositions of the present embodiments for removal of residues after plasma ashing of semiconductor substrates. Applicants selected example 11 as the formulation of the optimized composition and used for the removal of post-ashing residues from semiconductor substrates. To verify the optimal process parameters for the removal of residues after ashing of semiconductor substrates for the composition of the example 11 formulation. The applicant has carried out a verification of the rate of attack of aluminium at different temperatures as shown in figure 1, using the composition of the formulation of example 5. As can be seen from FIG. 1, applicants have found that the composition of the formulation of example 11 has a relatively low aluminum attack rate (less than that of the composition of the present invention) at operating temperatures of 10 to 50C) However, the aluminum attack rate increases significantly after temperatures exceeding 50 ℃, such as 60 ℃, and also exhibits excellent aluminum attack rate at 10 ℃ below room temperature. Thus, applicants verified that the operating temperature for the removal of the composition of the examples of the present invention from the residue was between 10 ℃ and 50 ℃. If too low an operating temperature results in residues during removal, it is recommended that the operating temperature be controlled to not exceed 50 ℃.

The conventional organic amine compound detergent is generally added with multifunctional organic acid (such as phthalic acid, oxalic acid and ethylenediamine tetraacetic acid-disodium (EDTA-2 Na)) as chelating agent for chelating metal in the aqueous solution of the composition, so as to chelate metal ions separated/dissolved out from the chip after semiconductor cleaning, and the stability and cleaning efficiency of the composition are all improved theoretically after the multifunctional organic acid is added based on the formulation of the composition in the embodiment of the application. However, applicants found that, as can be seen from Table 4 below, the aluminum attack rate was not decreased, but increased, after adding a certain amount of polyfunctional organic acid to the formulation of the composition of the present application. Therefore, the formula of the application does not contain polyfunctional organic acid, thereby not only reducing the cost, but also having better cleaning efficiency. That is, the composition of example 11 of the present application has a lower aluminum attack rate and is more protective of the aluminum wiring on the cleaned chip.

Table 4 formulation table of the compositions of inventive example 11 and comparative examples 1 to 3

The composition of example 11 of the present invention achieves the same cleaning effect and lower aluminum etch rate for removing post plasma ash residue on wafers after a high load wafer cleaning of 25 wafers of 12 inches per liter. At the same time, the etching rate of aluminum can be controlled toIs an excellent level of (a). This result shows that the composition of example 11 has excellent stability to water as the composition without the addition of polyfunctional organic acids, and the wafer cleaning achieves the desired results with a low aluminum attack rate. In summary, the composition of the formulation of the present invention provides better protection to aluminum lines on the cleaned wafer.

The embodiment of the present invention also provides a method for removing post-ashing residues from a semiconductor substrate, wherein the surface of the semiconductor substrate from which the post-ashing residues are to be removed is contacted with the compositions of embodiments 1 to 20 described above. In order to obtain a better removal effect, the temperature of the composition is 10-50 ℃ when the composition contacts with the surface of the semiconductor substrate.

Fig. 2-5 also show electron micrographs of different semiconductor structures (where fig. 2 and 3 are SRO/TEOS/SiN semiconductor structures, fig. 4 and 5 are TiW/Al semiconductor structures) before and after cleaning at 25 ℃ to remove post-ash residue using the composition of example 11 (fig. 2 and 4 are before removal, fig. 3 are after removal, and fig. 5 are after removal, where fig. 3 is 180 seconds and fig. 5 is 45 seconds). As can be seen from a comparison of fig. 2 and 3, fig. 2 shows the residues after dry etching plasma ashing, in which the wafer before processing is filled with spots, and fig. 3 shows the residues on the wafer have been removed. Fig. 4 shows the wafer being coated with dry etch plasma ashed residues, and fig. 5 shows the wafer having the residues removed.

The sources and specifications of the raw materials for the formulations in examples 1 to 20 and comparative examples 1 to 3 in the examples of the present invention are shown in Table 5 below:

TABLE 5 sources and specifications of raw materials

The directions in this embodiment are merely for convenience in describing the positional relationship between the respective members and the relationship of mutual cooperation. The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above examples, and all technical solutions belonging to the concept of the present invention belong to the protection scope of the present invention. It should be noted that modifications and adaptations to the present invention may occur to one skilled in the art without departing from the principles of the present invention and are intended to be within the scope of the present invention.

Claims

1. A composition for removing residues from ashing a semiconductor substrate, comprising, by weight percentage, 0.05-10 wt% of an organic amine compound, 0.001-10 wt% of a wetting agent, and 80-99.5 wt% of water, wherein the organic amine compound is at least one of monoethanolamine and tetramethylammonium hydroxide, the wetting agent comprises at least one of a polyol compound or a surfactant, the polyol compound comprises at least one of ethylene glycol, propylene glycol, glycerol, and polyethylene glycol, and the surfactant is Triton X-100.

2. The composition according to claim 1, wherein the organic amine compound further comprises at least one of N-methylethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, 2-(2-aminoethoxy)ethanol, N-ethylethanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, cyclohexylaminediethanol, and tetraethylammonium hydroxide.

3. The composition according to any one of claims 1-2, characterized in that it also comprises 0.1-10 wt% of a phenolic corrosion inhibitor.

4. The composition according to claim 3, wherein the phenolic corrosion inhibitor comprises at least one of tert-butylcatechol, catechol, resorcinol, 2,3-dihydroxybenzoic acid, and gallic acid.

5. The composition according to claim 1, wherein it has a pH value of 10 to 12.

The composition according to claim 1 , wherein the operating temperature thereof is 10 to 50° C.

7. A method for removing residues after ashing of a semiconductor substrate, characterized in that the surface of the semiconductor substrate from which the residues after ashing are to be removed is brought into contact with the composition according to any one of claims 1 to 6.

8 . The method according to claim 7 , wherein the temperature of the composition when in contact with the surface of the semiconductor substrate is 10-50° C.