BOE etching solution for thinning or removing silicon oxide in integrated circuit manufacturing process
By adding amide additives to the BOE etching solution and adjusting its content, the problem of poor SiO2/Si etching selection ratio and silicon oxide removal effect in the integrated circuit process is solved, and the etching effect is achieved with high selection ratio and uniformity. Ensures the smoothness and residue-freeness of the substrate.
Patent Information
- Application Number
- CN202310767078.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-27
- Publication Date
- 2024-12-27
AI Technical Summary
In the integrated circuit process, it is difficult for the existing BOE etching liquid to improve the SiO2/Si etching selection ratio while maintaining the SiO2 etching rate stable, and there are often problems of residual and high substrate roughness after silicon oxide is removed.
Using BOE etching solution containing hydrogen fluoride, ammonium fluoride and amide additives, the use of amide additives is adjusted to meet the specific composition ratio, so as to reduce the etching rate of Si, improve the SiO2/Si etching selection ratio, and reduce the etching solution. The surface tension improves the etch uniformity of silicon oxide.
The SiO2/Si etching selection ratio is improved, with no silicon oxide residue after etching, low roughness of the substrate silicon wafer, good etching uniformity, and significant silicon oxide removal effect.
Smart Images
Figure CN119193162A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of etching solutions, and in particular relates to a BOE etching solution used for thinning or removing silicon oxide in an integrated circuit manufacturing process. Background Art
[0002] As a key material in the IC (integrated circuit) process, silicon oxide has the functions of protecting and isolating devices, passivating surfaces, and serving as a dielectric and doping barrier layer. In the process, DHF (Diluted HF) or BOE etching solution (Buffered Oxide Etch) is often used to thin or remove silicon oxide. Among them, BOE etching solution has the characteristics of high etching rate and stable etching performance.
[0003] In the process of thinning or removing silicon oxide, the BOE etching solution needs to consider the etching rate on the one hand to ensure production capacity. On the other hand, the SiO2 / Si etching selectivity ratio needs to be considered to reduce corrosion to the substrate silicon and improve product quality. Under normal circumstances, different silicon oxide etching rates can be achieved by adjusting the HF and NH4F content in the BOE etching solution. For the SiO2 / Si etching selectivity ratio, the selectivity can be improved to a certain extent by increasing the SiO2 etching rate. However, during use, the SiO2 etching rate needs to be maintained within a certain range, and the SiO2 etching rate does not change much. Therefore, it is necessary to reduce the Si etching rate to improve the SiO2 / Si etching selectivity ratio when the SiO2 etching rate changes little. Summary of the invention
[0004] Based on this, the object of the present invention is to provide a BOE etching solution for thinning or removing silicon oxide in an integrated circuit process, which has the advantages of high SiO2 / Si etching selectivity, good etching uniformity and good silicon oxide removal effect.
[0005] To achieve the above object, the present invention adopts the following technical solution.
[0006] A BOE etching solution comprises the following components in percentage by mass: A% hydrogen fluoride, B% ammonium fluoride, C% amide additives, 0% to 0.5% etching rate regulator, and the balance is water;
[0007] The amide additive is selected from at least one of the compounds represented by the following general chemical formula: R1-CO-NH-R2; wherein R1 is selected from a substituted or unsubstituted alkyl group, and the substituent is at least one of a hydroxyl group and an amine group; and R2 is selected from a hydrocarbon group having a carbon number greater than 3;
[0008] The A% is 0.2% to 20%, B% is 1% to 40%, C% is ≤ 0.3%, and A, B and C satisfy the following relationship:
[0009] In some preferred embodiments, the A% is 0.25% to 20%.
[0010] More preferably, the A% is 0.35% to 20%.
[0011] In some preferred embodiments, the B% is 1.5% to 40%.
[0012] More preferably, the B% is 2%-40%.
[0013] In some embodiments, the mass percentage of the etching rate regulator is 0.0% to 0.3%.
[0014] In some embodiments, the amide additive is selected from at least one of 3-amino-N-butylpropaneamide, N-butyl-3-hydroxy-2,2-dimethylpropionamide, N-hexylbutanamide and N-butylbutanamide.
[0015] In some embodiments, the etch rate modifier is selected from at least one of an organic acid or an organic base.
[0016] In some preferred embodiments, the organic acid is selected from at least one of succinic acid, lactic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, and dodecanoic acid.
[0017] In some preferred embodiments, the organic base is selected from at least one of ethanolamine, triethanolamine, heptylamine, decylamine, undecylamine and dodecylamine.
[0018] The present invention provides a BOE etching solution for thinning or removing silicon oxide in an integrated circuit manufacturing process, wherein a suitable type of amide additive is added, and the amount of the amide additive used is adjusted according to the fluorine content in the BOE etching solution, so that the amounts of hydrogen fluoride, ammonium fluoride and the amide additive used satisfy a specific relationship, thereby obtaining a BOE etching solution with excellent performance: (1) when the SiO2 etching rate changes slightly, the SiO2 / Si etching selectivity ratio is effectively improved by reducing the Si etching rate; (2) the surface tension of the etching solution is reduced, and the etching uniformity of silicon oxide is significantly improved; (3) the silicon oxide removal effect is good, no silicon oxide residue is left after etching, and the roughness of the substrate silicon wafer is low. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 This is the roughness test result of BOE etching solution in Example 1.
[0020] Figure 2 This is the detection result of silicon oxide residue on the substrate after etching with BOE etching solution in Example 1. DETAILED DESCRIPTION
[0021] The experimental methods in the following examples of the present invention, where no specific conditions are specified, are usually carried out under conventional conditions or under conditions recommended by the manufacturers. The various commonly used chemical reagents used in the examples are all commercially available products.
[0022] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.
[0023] The terms "including" and "having" and any variations thereof of the present invention are intended to cover non-exclusive inclusions. For example, a process, method, device, product or equipment comprising a series of steps is not limited to the listed steps or modules, but may optionally include steps not listed, or may optionally include other steps inherent to these processes, methods, products or equipment.
[0024] The "and / or" mentioned in the present invention describes the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the associated objects before and after are in an "or" relationship.
[0025] The present embodiment provides a BOE etching solution, comprising the following components in percentage by mass: A% hydrogen fluoride (HF), B% ammonium fluoride (NH4F), C% amide additives, 0% to 0.5% etching rate regulator, and the balance is water;
[0026] The amide additive is selected from at least one of the compounds represented by the following general chemical formula: R1-CO-NH-R2; wherein R1 is selected from a substituted or unsubstituted alkyl group, and the substituent is at least one of a hydroxyl group and an amine group; R2 is selected from a hydrocarbon group having a carbon number greater than 3 (when the carbon number is less than or equal to 3, the steric hindrance is small and the protection of the silicon substrate is weak);
[0027] The A% is 0.2% to 20%, B% is 1% to 40%, C% is ≤ 0.3%, and A, B and C satisfy the following relationship (Relationship 1):
[0028] The BOE etching solution is composed of HF, NH4F, additives and H2O. Since atoms such as F and O have high electronegativity, they can form F...HN and O...HN hydrogen bonds with the NH structure in the amide additive in the solution, wherein the F...HN bond is stronger than O...HN and is more stable. As the F content in the BOE etching solution increases, the F...HN hydrogen bonds formed in the solution increase, and a stable BOE etching solution can be obtained by adding a lower amount of amide additives.
[0029] Hydrogen fluoride is the main etching agent in the BOE etching solution, and the preferred content is 0.25% to 20% (by weight), and more preferably 0.35% to 20% (by weight). When the content of hydrofluoric acid is within the above range, it can ensure that etching is carried out effectively, and at the same time, the etching rate can be controlled to be maintained within an appropriate range.
[0030] Ammonium fluoride mainly acts as a buffering etchant in the BOE etching solution, and the preferred content is 1.5% to 40% (by weight), and more preferably 2% to 40% (by weight). When the content of ammonium fluoride is within the above range, it can ensure that the etching rate is within a certain range, and can also continuously provide fluorine ions during the etching process to ensure the buffering capacity of the etching solution.
[0031] In the BOE etching solution, the addition amount C% (mass percentage content) of the amide additive, the addition amount A% of hydrogen fluoride and the addition amount B% of ammonium fluoride must satisfy the above relationship 1, and the addition amount C% (mass percentage content) of the amide additive should not exceed 0.3%. When the addition amount of the amide additive is too high (>0.3%), on the one hand, the solution may be turbid due to incomplete dissolution, affecting the etching effect, and on the other hand, the performance of the etching solution is not improved, resulting in increased costs.
[0032] In some embodiments, the etching rate regulator is selected from at least one of an organic acid or an organic base. The organic acid includes but is not limited to the following compounds: succinic acid, lactic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid; preferably, the content is 0% to 0.05%, more preferably, the content is 0% to 0.04%; the organic base includes but is not limited to the following compounds: ethanolamine, triethanolamine, heptylamine, decylamine, undecylamine, dodecylamine; preferably, the content is 0.01% to 0.05%, more preferably, the content is 0.01% to 0.03%.
[0033] The following describes the invention in conjunction with specific embodiments.
[0034] Examples 1 to 11
[0035] Embodiments 1 to 11 provide a BOE etching solution, respectively, wherein the BOE etching solution comprises hydrogen fluoride, ammonium fluoride, an amide additive and an etching rate regulator in amounts as shown in Table 1, and the balance is water; the mass percentages A%, B% and C% of the hydrogen fluoride, ammonium fluoride and amide additive in the BOE etching solution satisfy the following relationship:
[0036] The raw materials were weighed according to the amount used, and mixed evenly to obtain the BOE etching solutions described in Examples 1 to 11.
[0037] Comparative Examples 1 to 5
[0038] Comparative Examples 1 to 5 respectively provide a BOE etching solution, which has the same formula as that of the BOE etching solution described in Examples 1 to 11, except for the type or amount of the amide additive, as shown in Table 1.
[0039] The components were weighed according to the amount, mixed evenly, and the BOE etching solutions described in Comparative Examples 1 to 5 were obtained.
[0040] Table 1
[0041]
[0042]
[0043] The silicon oxide layer in the integrated circuit manufacturing process is etched using the etching solution in the above embodiment and comparative example: In the silicon oxide layer etching process, the wafer is etched with the etching solution at 22°C to 24°C (preferably 23°C in the present invention), and the etching time can be adjusted according to the thickness of the silicon oxide layer, generally 1-2 minutes. After the etching is completed, necessary cleaning and drying are performed. The performance of the solution is evaluated by the surface tension of the etching solution, substrate roughness, etching residue and SiO2 / Si etching selectivity ratio, and the results are filled in Table 2:
[0044] (1) Surface tension of etching solution: tested by surface tension meter (using ring method).
[0045] (2) Substrate roughness: tested by atomic force microscopy.
[0046] (3) Residue after etching: tested by scanning electron microscopy.
[0047] (4) SiO2 / Si etching selectivity ratio: refers to the ratio of SiO2 to Si etching rates. The etching rate is obtained by testing with an ellipsometer.
[0048] Table 2
[0049]
[0050]
[0051] The above results show that the BOE etching solution of the present invention (Examples 1 to 11) has low surface tension, a significantly high SiO2 / Si etching selectivity, a low substrate roughness after etching, no silicon oxide residue, and good etching uniformity. The roughness test results of the BOE etching solution and the substrate silicon oxide residue detection in Example 1 are shown as follows: Figure 1 and Figure 2 shown.
[0052] Compared with Example 1, the mass percentages A%, B% and C% of hydrogen fluoride, ammonium fluoride and amide additives in the BOE etching solution in Comparative Example 1 do not satisfy the above relationship 1; Comparative Example 2 does not contain amide additives, which leads to an increase in the surface tension of the BOE etching solution, a decrease in the SiO2 / Si etching selectivity, a decrease in the etching effect, and slight residue of silicon oxide on the substrate.
[0053] Compared with Example 5, the type of amide additive in Comparative Example 3 does not meet the requirements of the present invention, resulting in increased roughness, reduced SiO2 / Si etching selectivity, and slight residual silicon oxide on the substrate.
[0054] Compared with Example 1, the usage amount of the amide additive in Comparative Example 4 is greater than 0.3%. Although the roughness SiO2 / Si etching selectivity ratio does not decrease significantly, it will cause the solution to become turbid, affecting the subsequent etching process.
[0055] In summary, the present invention adds a suitable type of amide additive and adjusts the amount of the amide additive according to the fluorine content in the BOE etching solution so that the amounts of hydrogen fluoride, ammonium fluoride and the amide additive satisfy a specific relationship, thereby obtaining a BOE etching solution with excellent performance.
[0056] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0057] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.
Claims
1. A BOE etching solution, characterized in that: The invention comprises the following components in percentage by weight: A% hydrogen fluoride, B% ammonium fluoride, C% amide additive, 0% to 0.5% etching rate regulator, and the balance is water; The amide additive is selected from at least one of the compounds represented by the following general chemical formula: R1-CO-NH-R2; wherein R1 is selected from a substituted or unsubstituted alkyl group, and the substituent is at least one of a hydroxyl group and an amine group; and R2 is selected from a hydrocarbon group having a carbon number greater than 3; The A% is 0.2% to 20%, B% is 1% to 40%, C% is ≤ 0.3%, and A, B and C satisfy the following relationship:
2. The BOE etching solution according to claim 1, wherein The A% is 0.25% to 20%.
3. The BOE etching solution as claimed in claim 2, characterized in that The A% is 0.35% to 20%.
4. The BOE etching solution according to claim 1, wherein The B% is 1.5% to 40%.
5. The BOE etching solution as claimed in claim 4, characterized in that The B% is 2%-40%.
6. The BOE etching solution according to claim 1, characterized in that The mass percentage of the etching rate regulator is 0% to 0.3%.
7. The BOE etching solution according to any one of claims 1 to 6, characterized in that The amide additive is selected from at least one of 3-amino-N-butyl propane amide, N-butyl-3-hydroxy-2,2-dimethyl propionamide, N-hexyl butanamide and N-butyl butanamide.
8. The BOE etching solution according to any one of claims 1 to 6, characterized in that The etching rate regulator is selected from at least one of an organic acid or an organic base.
9. The BOE etching solution according to claim 8, characterized in that The organic acid is selected from at least one of succinic acid, lactic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid and dodecanoic acid.
10. The BOE etching solution according to claim 8, characterized in that The organic base is selected from at least one of ethanolamine, triethanolamine, heptylamine, decylamine, undecylamine and dodecylamine.