TW202020226A - Etching solution and method for selectively removing tan material relative to tin material - Google Patents

Abstract

An etching solution for selectively removing TaN material relative to TiN material is disclosed, which comprises: HF; an additive represented by the following formula (I); and a solvent. In addition, a method for selectively removing TaN material relative to TiN material is also disclosed, which use the aforesaid etching solution.

Herein, R₁ is NH₂ or OH, n is 1, 2 or 3, and m is 0 or 1.

Description

Etching solution and method for selectively removing tantalum nitride material relative to titanium nitride material

The present disclosure relates to an etching solution and method for selectively removing tantalum nitride material relative to titanium nitride material, which can exhibit an excellent selection ratio of tantalum nitride to titanium nitride.

As semiconductor transistors continue to shrink, in order to overcome the gate leakage current caused by the gate dielectric layer being too thin, the semiconductor has changed from traditional polysilicon/silicon oxynitride to metal/high dielectric (HKMG) materials. Among them, titanium nitride (TiN) and tantalum nitride (TaN) are commonly used work function metals of HKMG. In order to accelerate the output and flexibility of the process, the semiconductor market needs selective etching solutions for two metals.

The currently known hydrogen peroxide etchant can etch titanium nitride materials and obtain a relatively high etching selectivity ratio of titanium nitride to tantalum nitride. However, if you want to etch tantalum nitride without etching titanium nitride, you must choose an etching solution with a high selection ratio of tantalum nitride to titanium nitride. Although there are currently formula products with hydrogen peroxide and concentrated sulfuric acid and hydrofluoric acid with hydrogen peroxide, the etching rate of tantalum nitride is faster than that of titanium nitride, but the choice is less than 10.

In view of this, it is necessary to develop an etching solution and method for selectively removing tantalum nitride material relative to titanium nitride material, which can exhibit an excellent selection ratio of tantalum nitride to titanium nitride for application The tantalum nitride film is deposited on the substrate on the titanium nitride film to remove the upper layer of tantalum nitride film while leaving the lower layer of titanium nitride film.

The present disclosure relates to an etching solution and method for selectively removing tantalum nitride material relative to titanium nitride material. The removal rate of tantalum nitride material is greater than that of titanium nitride material.

The etching solution for selectively removing tantalum nitride material relative to the titanium nitride material disclosed in the present disclosure includes: a source of fluoride ions; an additive, as shown in the following formula (I):; and a water.

其中，R₁為NH₂或OH，n為1、2或3，而m為0或1。

Among them, R ₁ is NH ₂ or OH, n is 1, 2 or 3, and m is 0 or 1.

In addition, the method for selectively removing tantalum nitride material relative to the titanium nitride material of the present disclosure includes the following steps: providing the aforementioned etching liquid; and the etching liquid and a material containing a titanium nitride material and a tantalum nitride The substrates of the materials are in contact, and the etching liquid phase selectively removes the tantalum nitride material for the titanium nitride material.

In the etching solution for selectively removing tantalum nitride material relative to titanium nitride material in the present disclosure, by adding an additive of nitro aromatic or a mixture thereof to the etching solution, the removal of tantalum nitride material can be effectively improved Rate and maintain a low removal rate of titanium nitride material. Thereby, the selection ratio of tantalum nitride to titanium nitride can be greatly improved, and in the case of effectively removing the tantalum nitride material, the situation of removing the titanium nitride material is reduced.

In the present disclosure, the additive may be a nitro aromatic compound. Specific examples include, but are not limited to, 2,4,6-trinitrophenol, 2,4-dinitrophenol, 2,3-dinitrophenol, p-nitrophenol, M-nitrophenol, o-nitrophenol, 2,4,6-trinitroaniline, 2,4-dinitroaniline, 2,3-dinitroaniline, p-nitroaniline, m-nitroaniline, o Nitroaniline, 1,3,5-trinitrobenzene, 1,2-dinitrobenzene, 1,3-dinitrobenzene, 1,4-dinitrobenzene, nitrobenzene or mixtures thereof. In an embodiment of the present disclosure, p-nitrophenol, m-nitrophenol, o-nitrophenol, 2,4-dinitroaniline, 2,3-dinitroaniline, p-nitroaniline, m-nitro Aniline, o-nitroaniline, 1,3,5-trinitrobenzene, 1,2-dinitrobenzene, 1,3-dinitrobenzene, 1,4-dinitrobenzene, nitrobenzene or their mixture. In another embodiment of the present disclosure, the additive may be p-nitrophenol, p-nitroaniline, or a mixture thereof. By using additives, the etching efficiency of tantalum nitride can be appropriately improved to improve the selection ratio of tantalum nitride to titanium nitride.

In the etching solution of the present disclosure, the content of the fluoride ion source may be between 1wt% and 30wt%; the content of the additive may be between 0.01wt% and 2wt%; and the balance is water. In an embodiment of the present disclosure, the content of the fluoride ion source may be between 3wt% and 20wt%; the content of the additive may be between 0.01wt% and 1wt%; and the balance is water. In another embodiment of the present disclosure, the content of the fluoride ion source may be between 5 wt% and 15 wt%; the content of the additive may be between 0.03 wt% and 0.2 wt%; and the balance is water. When the concentration of the additive is increased, the removal rate of tantalum nitride can be greatly increased. On the contrary, the removal rate of titanium nitride is kept flat, thereby improving the selection ratio of tantalum nitride to titanium nitride.

The etching solution of the present disclosure may optionally further include an acid. Among them, the acid may be an organic acid or an inorganic acid. In an embodiment of the present disclosure, the acid may be sulfuric acid, phosphoric acid, nitric acid, hydroiodic acid, hydrobromic acid, perchloric acid, silicic acid, boric acid, acetic acid, propionic acid, lactic acid, glycolic acid, or a mixture thereof. In another embodiment of the present disclosure, the acid may be sulfuric acid, acetic acid, or a mixture thereof. Here, the amount of acid used is not particularly limited, and can be adjusted according to whether a strong acid or a weak acid is used. In an embodiment of the present disclosure, the acid content may be between 0.1 wt% and 30 wt%. In another embodiment of the present disclosure, the acid content may be between 0.5wt% and 25wt%. In another embodiment of the present disclosure, the acid content may be between 0.5 wt% and 20 wt%.

In the present disclosure, the acid is mainly used to adjust the pH of the etching solution. In an embodiment of the present disclosure, by using an acid, the pH of the etching solution is adjusted to 1 or below. In another embodiment of the present disclosure, the acid is used to adjust the pH of the etching solution between 1 and 0 (0≦pH≦1).

In the present disclosure, when the etchant is in contact with a substrate containing titanium nitride material and tantalum nitride material to remove the tantalum nitride material, the reaction time is not particularly limited. In an embodiment of the present disclosure, the reaction time between the etching solution and the substrate may be 2 minutes or more. In another embodiment of the present disclosure, the reaction time between the etching solution and the substrate may be between 2 minutes and 30 minutes. In yet another embodiment of the present disclosure, the reaction time between the etching solution and the substrate may be 3 minutes or more. In a further embodiment of the present disclosure, the reaction time between the etching solution and the substrate may be between 3 minutes and 30 minutes. By reacting the etching solution with the substrate for a predetermined time, the tantalum nitride material can be effectively removed to obtain the desired selection ratio of tantalum nitride to titanium nitride. When the reaction time is less than the aforementioned lower limit, there is no significant difference in the removal rates of tantalum nitride and titanium nitride. When the reaction time is within the previously defined range, the removal rate of tantalum nitride can be significantly better than that of titanium nitride.

In addition, in the present disclosure, when the etchant is in contact with the substrate containing the titanium nitride material and the tantalum nitride material to remove the tantalum nitride material, the reaction temperature is also not particularly limited. In an embodiment of the present disclosure, the reaction temperature when the etching liquid contacts the substrate may be between 20°C and 40°C. In another embodiment of the present disclosure, the reaction temperature when the etching liquid contacts the substrate may be between 25°C and 35°C. When the reaction temperature is less than the aforementioned lower limit, the reaction rate is slow, and tantalum nitride cannot be effectively removed. When the reaction temperature is greater than the aforementioned upper limit, although the removal rate of tantalum nitride increases, the removal rate of titanium nitride also increases, and the desired selection ratio of tantalum nitride to titanium nitride cannot be obtained.

Furthermore, in the present disclosure, according to the amount of additives added, the reaction temperature and the reaction time, different etching selection ratios of tantalum nitride materials relative to titanium nitride materials can be obtained. In an embodiment of the present disclosure, the etching selection ratio of tantalum nitride material relative to titanium nitride material (selection ratio of tantalum nitride to titanium nitride) It can be equal to or greater than 10, that is, tantalum nitride removal rate/titanium nitride removal rate ≧10. In another embodiment of the present disclosure, the selection ratio of tantalum nitride to titanium nitride may be between 10 and 300, that is, 10≦tantalum nitride removal rate/titanium nitride removal rate≦300. In yet another embodiment of the present disclosure, the selection ratio of tantalum nitride to titanium nitride may be equal to or greater than 50, that is, tantalum nitride removal rate/titanium nitride removal rate ≧50. In a further embodiment of the present disclosure, the selection ratio of tantalum nitride to titanium nitride may be between 50 and 300, that is, 50≦tantalum nitride removal rate/titanium nitride removal rate≦300.

The following is a description of the implementation of the present disclosure through specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present disclosure from the content disclosed in this specification. This disclosure can also be implemented or applied by other different specific embodiments. Various details in this specification can also be directed to different viewpoints and applications, and various modifications and changes can be made without departing from the spirit of this creation.

instrument

In the following embodiments of the present disclosure, a scanning electron microscope is used, which is an instrument for surface detection, which can analyze the surface and cross-sectional characteristics of the material. The built-in scale of the electron microscope can be used to measure the etching depth. N&K machine uses optical method to measure the film thickness.

Test material

In the following embodiments of the present disclosure, commercially available wafers plated with TiN and TaN thin films are used, and the film thickness is 1000Å. The wafers coated with TiN and TaN thin films are cut to a size of 2 cm x 2 cm, and the thin films are etched by immersion. The film thickness was measured with a four-point probe before and after etching.

Use the balance to take the appropriate amount of chemicals, and formulate an aqueous solution with the specified ratio according to Table 1 below. In the following formulas 2 to 5, the additive used is p-nitroaniline.

Test 1-Testing of different additive concentrations

Place the beaker in a water bath. After the temperature of the etching solution rises to 25°C, the wafers coated with TiN and TaN films can be placed in the etching solution for etching test. The etching time is 2 minutes. The results are shown in Table 2 below.

As shown in the results of Table 2, in the formulations 2 to 5 containing additives, the selection ratio of tantalum nitride to titanium nitride can be improved; in particular, in the formulations 3 to 5 containing additives, tantalum nitride is nitrided The selection ratio of titanium can exceed 100. This result shows that the higher the additive concentration, the higher the TaN etching rate and the TiN etching is flat. Therefore, as the additive concentration is higher, the selection ratio of tantalum nitride to titanium nitride is higher.

Test 2-Testing at different etching temperatures

Place the beaker in the water bath and use the etching solution shown in Table 3 below. After the temperature rises to the specified temperature, the TiN and TaN thin film-coated wafers can be placed in the etching solution for the etching test. The etching time is 2 minutes. The results are shown in Table 4 below.

As shown in the results of Table 4, when the etching temperature is 25°C and 35°C, the selection ratio of tantalum nitride to titanium nitride can both exceed 100. In particular, when the etching temperature is 25°C, the selection ratio of tantalum nitride to titanium nitride may exceed 200.

Test 3-Test with different etching time

Place the beaker in a water bath, and after the temperature of the etching solution (Formulation 6) rises to 25°C, the wafers coated with TiN and TaN films can be placed in the etching solution for etching test. The results are shown in Table 5 below.

As shown in the results of Table 5, when the etching time is 2 minutes or more, the selection ratio of tantalum nitride to titanium nitride can all exceed 50. In particular, when the etching time is 3 minutes, the selection ratio of tantalum nitride to titanium nitride is about 200.

Test 4-Testing of different additives

Use the balance to take the appropriate amount of chemicals, and formulate an aqueous solution with the specified ratio according to Table 5 below. In addition, the beaker is placed in a water bath, and at room temperature, the wafers coated with TiN and TaN thin films can be put into the etching solution for etching test. The etching time and test results are shown in Table 6 below.

As shown in the results of Table 6, Formulation 7 without additives hardly exhibited the selection ratio of tantalum nitride to titanium nitride. However, formulas 8 to 15 using additives can all exhibit a good selection ratio of tantalum nitride to titanium nitride.

Test 5-Test of different acetic acid usage

The etching solution is configured with the balance of the appropriate amount of chemicals, the HF usage is 5wt%; the additive is p-nitroaniline, the usage is 0.03wt%; and the usage of acetic acid is shown in Table 7. In addition, the beaker is placed in a water bath. At room temperature, the wafers coated with TiN and TaN films can be placed in an etching solution for etching test. The etching time is 2 minutes. The test results are shown in Table 7 below.

As shown in the results in Table 7, regardless of whether an acid is used, it can exhibit a good selection ratio of tantalum nitride to titanium nitride.

Test 6-Test of different nitric acid usage

The etching solution was configured with the appropriate amount of chemicals on the balance, HF usage was 5wt%; additive was nitrobenzene, usage was 0.03wt%; acetic acid usage was 6wt%; nitric acid usage was shown in Table 8. In addition, the beaker is placed in a water bath. At room temperature, the wafers coated with TiN and TaN films can be placed in an etching solution for etching test. The etching time is 2 minutes. The test results are shown in Table 8 below.

As shown in the results of Table 8, when nitric acid and acetic acid are used in combination, a good selection ratio of tantalum nitride to titanium nitride can also be exhibited.

Test 7-Test of different sulfuric acid usage

The etching solution was configured with the balance of the appropriate amount of chemicals, the HF usage was 5wt%; the additive was p-nitrophenol, the usage was 0.03wt%; the acetic acid usage was 6wt%; and the sulfuric acid usage was shown in Table 9. In addition, the beaker is placed in a water bath. At room temperature, the wafers coated with TiN and TaN films can be placed in an etching solution for etching test. The etching time is 2 minutes. The test results are shown in Table 9 below.

As shown in the results of Table 9, when sulfuric acid and acetic acid are used in combination, they can also exhibit a good selection ratio of tantalum nitride to titanium nitride.

Test 8-Test of different phosphoric acid usage

The etching solution was configured with the appropriate amount of chemicals on the balance, the HF usage was 7wt%; the additive was p-nitroaniline, usage was 0.03wt%; the usage of acetic acid was 20wt%; the usage of phosphoric acid is shown in Table 10. In addition, the beaker is placed in a water bath. At room temperature, the wafers coated with TiN and TaN films can be placed in an etching solution for etching test. The etching time is 2 minutes. The test results are shown in Table 10 below.

As shown in the results in Table 10, when nitric acid is used in combination with acetic acid, it can also exhibit a good selection ratio of tantalum nitride to titanium nitride.

In summary, in the present disclosure, when an appropriate amount of additives is added to the etching solution and the etching is performed at an appropriate etching reaction temperature, after an appropriate etching reaction time, tantalum nitride to nitride exceeding the target value of 50 can be obtained Selection ratio of titanium. In particular, under certain conditions, the selection of tantalum nitride over titanium nitride The select ratio can be as high as about 200. In this way, the etching solution with additives added in the present disclosure can effectively improve the etching rate of tantalum nitride; when using the etching solution with additives in the present disclosure to etch a substrate containing both titanium nitride material and tantalum nitride material, Tantalum nitride can be effectively removed without removing titanium nitride. Therefore, the etching solution with additives added in the present disclosure can be used to deposit tantalum nitride film on the substrate on the titanium nitride film to remove the upper layer of tantalum nitride film while leaving the lower layer of titanium nitride film.

The above embodiments are only examples for the convenience of description. The scope of the rights claimed in this disclosure should be subject to the scope of the patent application, and not limited to the above embodiments.

Claims (18)

An etching solution for selectively removing tantalum nitride material relative to titanium nitride material includes: a source of fluoride ions; and an additive, as shown in the following formula (I):

Where R ₁ is NH ₂ or OH, n is 1, 2 or 3, and m is 0 or 1; and monohydrate. The etching solution as described in item 1 of the patent application scope, wherein the additive is 2,4,6-trinitrophenol, 2,4-dinitrophenol, 2,3-dinitrophenol, p-nitro Phenol, m-nitrophenol, o-nitrophenol, 2,4,6-trinitroaniline, 2,4-dinitroaniline, 2,3-dinitroaniline, p-nitroaniline, m-nitroaniline , O-nitroaniline, 1,3,5-trinitrobenzene, 1,2-dinitrobenzene, 1,3-dinitrobenzene, 1,4-dinitrobenzene, nitrobenzene or mixtures thereof . The etching solution as described in item 1 of the patent application scope, wherein the content of the fluoride ion source is between 1wt% and 30wt%; the content of the additive is between 0.01wt% and 2wt%; and the balance is water. The etching solution as described in item 1 of the patent application, wherein the source of the fluoride ion is hydrofluoric acid, ammonium fluoride, tetramethylammonium fluoride, fluorosilicic acid or a mixture thereof. The etching solution as described in item 1 of the patent application scope further includes an acid whose content is between 0.1 wt% and 30 wt%. The etching solution as described in item 5 of the patent application scope, wherein the acid is sulfuric acid, phosphoric acid, nitric acid, hydroiodic acid, hydrobromic acid, perchloric acid, silicic acid, boric acid, acetic acid, propionic acid, lactic acid, glycolic acid Or mixtures thereof. As for the etching solution described in item 1 of the patent application, the pH of the etching solution is 1 or less. The etching solution as described in item 1 of the patent application range, wherein the etching selection ratio of the tantalum nitride material relative to the titanium nitride material is equal to or greater than 10. A method for selectively removing tantalum nitride material relative to titanium nitride material includes the following steps: providing an etching solution, the etching solution including: a source of fluoride ions; an additive, as shown in the following formula (I); and A water

Where R ₁ is NH ₂ or OH, n is 1, 2 or 3, and m is 0 or 1; and the etchant is in contact with a substrate containing a titanium nitride material and a tantalum nitride material, and The etching liquid phase selectively removes the tantalum nitride material for the titanium nitride material. The method as described in item 9 of the patent application scope, wherein the additive is 2,4,6-trinitrophenol, 2,4-dinitrophenol, 2,3-dinitrophenol, p-nitrophenol , M-nitrophenol, o-nitrophenol, 2,4,6-trinitroaniline, 2,4-dinitroaniline, 2,3-dinitroaniline, p-nitroaniline, m-nitroaniline, O-Nitroaniline, 1,3,5-trinitrobenzene, 1,2-dinitrobenzene, 1,3-dinitrobenzene, 1,4-dinitrobenzene, nitrobenzene or mixtures thereof. The method as described in item 9 of the patent application range, wherein the content of the fluoride ion source is between 1 wt% and 30 wt%; the content of the additive is between 0.01 wt% and 2 wt%; and the balance is water. The method according to item 9 of the patent application scope, wherein the source of the fluoride ion is hydrofluoric acid, ammonium fluoride, tetramethylammonium fluoride, fluorosilicic acid, or a mixture thereof. The method as described in item 9 of the patent application range, wherein the etching solution further comprises an acid, the content of which is between 0.1 wt% and 30 wt%. The method according to item 13 of the patent application scope, wherein the acid is sulfuric acid, phosphoric acid, nitric acid, hydroiodic acid, hydrobromic acid, perchloric acid, silicic acid, boric acid, acetic acid, propionic acid, lactic acid, glycolic acid or mixture. The method as described in item 9 of the patent application range, wherein the pH of the etching solution is 1 or less. The method as described in item 9 of the patent application range, wherein the etching selection ratio of the tantalum nitride material relative to the titanium nitride material is equal to or greater than 10. The method according to item 9 of the patent application scope, wherein the reaction time of the contact between the etching solution and the substrate is 2 minutes or more. The method as described in item 9 of the patent application range, wherein the reaction temperature of the contact between the etching solution and the substrate is between 20°C and 40°C.