TiN and Ti metal film etching solution and preparation method thereof

Abstract

The present invention specifically relates to a TiN and Ti metal film etching solution and a preparation method thereof. The etching solution mainly comprises an oxidant, a stabilizer, an ammonium salt, an oxygen promoter, a surfactant and acetic acid. The etching solution uses an oxidant to oxidize TiN and Ti to form oxides for etching; the ammonium salt can be used as a corrosion inhibitor to complex with metal ions; an inorganic acid or an organic acid is used as a secondary oxidant to increase the oxidizing property of the oxidant and provide sufficient hydrogen ions, so that the concentration of the oxidant is maintained at a high level, the etching rate is maintained stable, and the use / storage life of the etching solution is extended; the surfactant can reduce the surface tension of the solution and promote the etching uniformity and integrity of TiN and Ti. The etching solution used according to the method of the present invention can ensure that the etching rates of the TiN metal film and the Ti metal film are basically the same (the difference between the etching rates of the two is ≤17 Å / min).

Description

Technical Field

[0001] The invention belongs to the field of electronic chemicals, and in particular relates to a TiN and Ti metal film etching solution and a preparation method thereof. Background Art

[0002] In recent years, the field of microelectronic device manufacturing has developed rapidly, and electronic equipment is required to be more miniaturized, highly functional, and thinner, that is, the microelectronic devices in integrated circuits are required to be more miniaturized and integrated. TiN and Ti metal layers are used as conductive layers to form fine metal wires through etching, which are widely used in metal wiring of semiconductor devices to achieve interconnection between different devices. In order to ensure the uniformity and flatness of the etched surface, it is necessary to control the etching rates of TiN and Ti to remain basically consistent, and the difference in the etching rates between the two should be as small as possible.

[0003] The metal etching liquid reported so far is generally only used for etching a single TiN or Ti metal layer, that is, selectively etching a single TiN or Ti metal layer, and cannot achieve the etching effect of using the same etching liquid to etch the TiN and Ti metal layers separately and achieve a small difference in the etching rates of the two. Based on this, a TiN and Ti metal film etching liquid and a preparation method thereof are developed, which can solve the purpose of using the same liquid to etch the TiN and Ti metal layers separately and meet the purpose of achieving basically the same etching rates of the two. Summary of the invention

[0004] The present invention aims to solve the problem that the etching rates of TiN and Ti metal layers are greatly different when the same etching solution is used to etch TiN and Ti metal thin films in the existing semiconductor integrated circuit process. The invention aims to provide a TiN and Ti metal thin film etching solution that can greatly shorten the etching rates of the two metals and keep the etching rates of TiN and Ti metal layers basically consistent. To achieve the purpose of the invention, the raw materials of the present invention include: 10-25wt% of an oxidant, 0.3-2wt% of a stabilizer; 7-35wt% of an ammonium salt; 1-8wt% of an oxygen enhancer; 0.01-0.3wt% of a surfactant; and the rest of acetic acid.

[0005] In the implementation case, the oxidant is hydrogen peroxide; the stabilizer is acetaminophen; the ammonium salt can be at least one of ammonium sulfate, ammonium acetate or other nitrogen-containing non-oxidizing ammonium salts, and the ammonium salt cannot be a halogen-containing ammonium salt; the oxygen promoter is at least one of acetic acid, nitric acid, phosphoric acid or sulfuric acid; the surfactant is at least one of coconut oil fatty acid diethanolamide, cocamidopropyl betaine, sodium α-olefin sulfonate, 1,2-hydroxystearic acid diethanolamide, sodium octyl sulfosuccinate mixed diester, alkyl trimethylammonium carboxylate, N-acyl amino acid, N-acyl amino acid salt, N-lauroyl glutamate and glycerol polyoxyethylene ether fatty acid ester, polyethylene glycol.

[0006] In the implementation case, the preparation method of the TiN and Ti metal film etching solution is: weighing the oxidant, stabilizer, ammonium salt, oxygen enhancer, surfactant and acetic acid respectively in proportion, preparing the etching solution in the order of oxidant, stabilizer, ammonium salt, oxygen enhancer and surfactant, acetic acid, or preparing the etching solution in any addition order, and cooling to room temperature after the preparation is evenly mixed.

[0007] In the implementation case, the raw material concentration of the oxidant dihydrate is 33-36%.

[0008] In the implementation case, the etching method is to immerse the TiN and Ti metal films in etching solutions respectively, the etching temperature is 55-65° C., and the etching time is 1-2 min.

[0009] In the implementation case, the TiN and Ti metal films are first cut into 1.6cm*1.6cm metal sheets, and the metal thicknesses are obtained through four-probe testing. The four-probe test selects four fixed center points of the metal film for testing and calculates the average thickness of the four points, which is the thickness of a metal sheet.

[0010] In the implementation case, the thickness of the TiN metal film is about 800nm, and the substrate is Si and SiO2; the thickness of the TiN metal film is about 1000nm, and the substrate is Si and SiO2.

[0011] In the implementation case, the TiN and Ti metal films are metal films that have been treated to remove the oxide layer. The method for removing the metal oxide layer is: the TiN and Ti metal films are immersed in 33-36% hydrogen peroxide at room temperature and under stirring conditions for 5 to 10 minutes. After 5 to 10 minutes, the thickness of the metal film is reduced by about 10% compared with that before the hydrogen peroxide treatment. This ensures that the TiN and Ti metal films in the actual examples are metal films without an oxide layer, making the experimental data in the actual examples more scientific.

[0012] The etching method described in this paper has an etching rate of TiN metal film of The etching rate of Ti is And under the same etching conditions, the difference in the etching rate between the two is

[0013] Advantages and beneficial effects of the present invention:

[0014] 1) The invention has a simple formula and the preparation steps are not complicated, but can achieve etching of TiN and Ti metal layers respectively, and the difference in etching rate between the two after etching is very small (the difference in etching rate between the two is ≤ ).

[0015] 2) Inorganic acid or organic acid as a secondary oxidant can not only increase the oxidizability of hydrogen peroxide but also provide sufficient hydrogen ions, so that the concentration of hydrogen peroxide can be maintained at a high level for a long time, maintaining a stable etching rate; it can also extend the use / storage life of the etching solution.

[0016] 3) Ammonium salts such as ammonium sulfate can act as corrosion inhibitors to complex with metal ions in the solution and control the etching rate.

[0017] 4) Surfactants such as coconut oil fatty acid diethanolamide can reduce the surface tension of the solution, improve the wettability of the metal layer with the solution, and promote the etching uniformity and integrity of TiN and Ti.

[0018] 5) Using acetic acid as a solvent can reduce the surface tension and increase the wettability of the solution. At the same time, acetic acid can be used as a buffer to maintain the pH value of the solution stable.

[0019] 6) The stabilizer acetaminophen can prolong the etching life of the oxidant hydrogen peroxide and stabilize the etching effect. DETAILED DESCRIPTION

[0020] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with embodiments, but the content of the present invention is not limited to the following examples.

[0021] Example 1

[0022] A TiN and Ti metal film etching solution, the components and contents of which are shown in Table 1:

[0023] Table 1 Components and contents of Example 1

[0024]

[0025] Etching liquid was prepared according to the components and contents listed in Table 3, and then the 1.6cm*1.6cm TiN metal sheet and 1.6cm*1.6cm Ti metal film sheet after the oxide layer was removed were etched respectively. The temperature of the etching liquid was controlled at 60°C and the etching time was 1min. After the etching was completed, the metal sheet was cleaned and dried and the thickness was tested. The etching effect is summarized in Table 4. The etching rate of TiN in Example 1 is The etching rate of Ti is The difference in etching rate between the two

[0026] Example 2

[0027] Same as Example 1, only the oxidant is adjusted to 10% hydrogen peroxide, and the contents of other components remain unchanged, which is set as Example 2. The etching steps and testing methods are the same as Example 1.

[0028] The etching effect is shown in Table 4. Compared with Example 1, the etching rates of TiN and Ti metal films in this embodiment are both reduced, wherein the etching rate of TiN is The etching rate of Ti is The difference in etching rate between the two

[0029] Example 3

[0030] Same as Example 1, only the stabilizer is adjusted to 1% sulfuric acid, and the contents of other components remain unchanged, which is set as Example 3. The etching steps and testing methods are the same as Example 1.

[0031] The etching effect is shown in Table 4. Compared with Example 1, the etching rates of TiN and Ti metal films in this embodiment are increased, wherein the etching rate of TiN is The etching rate of Ti is The difference in etching rate between the two

[0032] Example 4

[0033] The same as Example 1, only the ammonium salt is adjusted to 20% ammonium sulfate, and the contents of other components remain unchanged, which is set as Example 4. The etching steps and testing methods are the same as Example 1.

[0034] The etching effect is shown in Table 4. Compared with Example 1, the etching rates of TiN and Ti metal films in this embodiment are both reduced, wherein the etching rate of TiN is The etching rate of Ti is The difference in etching rate between the two

[0035] Example 5

[0036] Same as Example 1, the oxidant is adjusted to 20% hydrogen peroxide, the ammonium salt ammonium sulfate is adjusted to 30%, the surfactant is adjusted to 0.05% cocamidopropyl betaine, and the contents of other components remain unchanged, set to Example 5, the etching steps and testing methods are the same as Example 1.

[0037] The etching effect is shown in Table 4. Compared with Example 1, the etching rates of TiN and Ti metal films in this embodiment are both reduced, wherein the etching rate of TiN is The etching rate of Ti is The difference in etching rate between the two

[0038] Example 6

[0039] Same as Example 1, the oxidant is adjusted to 23% hydrogen peroxide, the ammonium salt ammonium sulfate is 27%, the oxygen enhancer sulfuric acid is 5%, and the contents of other components remain unchanged, set to Example 6, the etching steps and test methods are the same as Example 1.

[0040] The etching effect is shown in Table 4. Compared with Example 1, the etching rates of TiN and Ti metal films in this embodiment are both reduced, wherein the etching rate of TiN is The etching rate of Ti is The difference in etching rate between the two

[0041] Example 7

[0042] Same as Example 1, the oxidant is adjusted to 20% hydrogen peroxide, the ammonium salt ammonium sulfate is 24%, the surfactant is adjusted to 0.6% 1,2-hydroxystearic acid diethanolamide, and the contents of other components remain unchanged, set to Example 7, the etching steps and testing methods are the same as Example 1.

[0043] The etching effect is shown in Table 4. Compared with Example 1, the etching rates of TiN and Ti metal films in this embodiment are both reduced, wherein the etching rate of TiN is The etching rate of Ti is The difference in etching rate between the two

[0044] Example 8

[0045] Same as Example 1, except that the oxygen enhancer is adjusted to 5% phosphoric acid, the surfactant is adjusted to 0.06% alkyl trimethyl ammonium carboxylate, and the contents of other components remain unchanged, and the setting is set to Example 8. The etching steps and test methods are the same as Example 1.

[0046] The etching effect is shown in Table 4. Compared with Example 1, the etching rates of TiN and Ti metal films in this embodiment are increased, wherein the etching rate of TiN is The etching rate of Ti is The difference in etching rate between the two

[0047] Example 9

[0048] Same as Example 1, only the oxidant is adjusted to 1.7% nitric acid, and the contents of other components remain unchanged, which is set as Example 9. The etching steps and testing methods are the same as Example 1.

[0049] The etching effect is shown in Table 4. Compared with Example 1, the etching rates of TiN and Ti metal films in this embodiment are both reduced, wherein the etching rate of TiN is The etching rate of Ti is The difference in etching rate between the two

[0050] Example 10

[0051] The same as Example 1, only the ammonium salt is adjusted to 12% ammonium acetate, and the contents of other components remain unchanged, and it is set to Example 10. The etching steps and testing methods are the same as Example 1.

[0052] The etching effect is shown in Table 4. Compared with Example 1, the etching rates of TiN and Ti metal films in this embodiment are both reduced, wherein the etching rate of TiN is The etching rate of Ti is The difference in etching rate between the two

[0053] Embodiment 11

[0054] Same as Example 1, only the oxidant hydrogen peroxide was adjusted from 15% to 10%, and the contents of other components remained unchanged, which was set as Example 11. The etching steps and testing methods were the same as those in Example 1.

[0055] The etching effect is shown in Table 4. Compared with Example 1, the etching rates of TiN and Ti metal films in this embodiment are both reduced, wherein the etching rate of TiN is The etching rate of Ti is The difference in etching rate between the two

[0056] Example 12

[0057] The same as Example 1, only the surfactant is adjusted to 0.06% of glycerol polyoxyethylene ether fatty acid ester, and the contents of other components remain unchanged, and it is set to Example 12. The etching steps and testing methods are the same as Example 1.

[0058] The etching effect is shown in Table 4. Compared with Example 1, the etching rates of TiN and Ti metal films in this embodiment are both reduced, wherein the etching rate of TiN is The etching rate of Ti is The difference in etching rate between the two

[0059] Embodiment 13

[0060] Same as Example 1, only the surfactant coconut oil fatty acid diethanolamide is adjusted to 0.1%, and the contents of other components remain unchanged, which is set as Example 13. The etching steps and testing methods are the same as Example 1.

[0061] The etching effect is shown in Table 4. Compared with Example 1, the etching rates of TiN and Ti metal films in this embodiment are both reduced, wherein the etching rate of TiN is The etching rate of Ti is The difference in etching rate between the two

[0062] Embodiment 14

[0063] The same as Example 1, only the surfactant is changed to 0.05% of octyl sulfosuccinic acid mixed diester sodium, and the contents of other components remain unchanged, and it is set to Example 14. The etching steps and testing methods are the same as Example 1.

[0064] The etching effect is shown in Table 4. Compared with Example 1, the etching rates of TiN and Ti metal films in this embodiment are both reduced, wherein the etching rate of TiN is The etching rate of Ti is The difference in etching rate between the two

[0065] Embodiment 15

[0066] Same as Example 1, the component content remains unchanged, only the temperature is adjusted to 55°C, set as Example 15, the etching steps and testing methods are the same as Example 1.

[0067] The etching effect is shown in Table 4. Compared with Example 1, the etching rates of TiN and Ti metal films in this embodiment are both reduced, wherein the etching rate of TiN is The etching rate of Ti is The difference in etching rate between the two

[0068] Example 16

[0069] Same as Example 1, the component contents remain unchanged, only the stabilizer acetaminophen is adjusted to 1%, and it is set as Example 15. The etching steps and testing methods are the same as Example 1.

[0070] The etching effect is shown in Table 4. Compared with Example 1, the etching rates of TiN and Ti metal films in this embodiment are both reduced, wherein the etching rate of TiN is The etching rate of Ti is The difference in etching rate between the two

[0071] Embodiment 17

[0072] Same as Example 1, the component contents remain unchanged, only the stabilizer is adjusted to 1.3%, and it is set as Example 16. The etching steps and testing methods are the same as Example 1.

[0073] The etching effect is shown in Table 4. Compared with Example 1, the etching rates of TiN and Ti metal films in this embodiment are both reduced, wherein the etching rate of TiN is The etching rate of Ti is The difference in etching rate between the two

[0074] Comparative Example 1

[0075] The same as Example 1, only the oxidant is changed to 15% sulfuric acid, and the contents of other components remain unchanged, which is set as Comparative Example 1. The etching steps and testing methods are the same as those of Example 1.

[0076] The etching effect is shown in Table 4. Compared with Example 1, the TiN and Ti metal films are hardly etched in this embodiment, and the etching rate of TiN is The etching rate of Ti is The difference in etching rate between the two

[0077] Comparative Example 2

[0078] The same as Example 1, the component content remains unchanged, only the temperature is adjusted to 45° C., which is set as Comparative Example 2. The etching steps and testing methods are the same as those of Example 1.

[0079] The etching effect is shown in Table 4. Compared with Example 1, the TiN and Ti metal films are hardly etched in this embodiment, and the etching rate of TiN is The etching rate of Ti is The difference in etching rate between the two

[0080] Comparative Example 3

[0081] The same as Example 1, except that the remaining acetic acid is replaced with phosphoric acid, and the contents of other components remain unchanged, is set as Comparative Example 3, and the etching steps and testing methods are the same as those of Example 1.

[0082] The etching effect is shown in Table 4. Compared with Example 1, the TiN and Ti metal films are hardly etched in this embodiment, and the etching rate of TiN is The etching rate of Ti is The difference in etching rate between the two

[0083] Comparative Example 4

[0084] The same as Example 1, without adding ammonium salt, and the contents of other components remain unchanged, is set as Comparative Example 4, and the etching steps and testing methods are the same as those in Example 1.

[0085] The etching effect is shown in Table 4. Compared with Example 1, the etching rates of TiN and Ti metal films in this embodiment are increased, wherein the etching rate of TiN is The etching rate of Ti is The difference in etching rate between the two

[0086] Comparative Example 5

[0087] The same as Example 1, without adding a stabilizer, and the contents of other components remain unchanged, is set as Comparative Example 5, and the etching steps and testing methods are the same as those of Example 1.

[0088] The etching effect is shown in Table 4. Compared with Example 1, the etching rates of TiN and Ti metal films in this embodiment are increased, wherein the etching rate of TiN is The etching rate of Ti is The difference in etching rate between the two

[0089] Table 4 Etching effect of each embodiment

[0090]

[0091]

[0092] Obviously, the above embodiments are only examples for clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the protection scope of the invention.

Claims

1. A TiN and Ti metal thin film etching solution, characterized in that: The etching solution comprises: 10-25 wt% of an oxidant; 1-2 wt% of a stabilizer; 7-35 wt% of an ammonium salt; 1-8 wt% of an oxygen enhancer; 0.01-0.3 wt% of a surfactant; and the remaining acetic acid, wherein the oxidant is hydrogen peroxide, the stabilizer is acetaminophen, the ammonium salt is ammonium sulfate or ammonium acetate, and the oxygen enhancer is at least one of acetic acid, nitric acid, phosphoric acid or sulfuric acid.

2. A TiN and Ti metal film etching solution according to claim 1, characterized in that: The mass concentration of the oxidant hydrogen peroxide is 33~36%.

3. A TiN and Ti metal film etching solution according to claim 1, characterized in that, The surfactant is at least one of coconut oil fatty acid diethanolamide, cocamidopropyl betaine, sodium α-olefin sulfonate, 1,2-hydroxystearic acid diethanolamide, sodium octyl sulfosuccinate mixed diester, alkyl trimethyl ammonium carboxylate, N-acyl amino acid, N-acyl amino acid salt, N-lauroyl glutamate, glycerol polyoxyethylene ether fatty acid ester and polyethylene glycol.

4. The method for preparing a TiN and Ti metal film etching solution according to any one of claims 1 to 3, wherein: The method comprises the following steps: weighing an oxidant, an ammonium salt, an oxygen enhancer, a surfactant and acetic acid respectively in proportion, preparing an etching solution in any order of addition, and cooling the solution to room temperature after the solution is mixed evenly.

5. A method for etching using a TiN and Ti metal film etching solution according to any one of claims 1 to 3, characterized in that: First, the TiN and Ti metal films are immersed in hydrogen peroxide with a mass fraction of 33-36% at room temperature and under stirring conditions for 5-10 min; then the immersed TiN and Ti metal films are immersed in etching solution, and the etching is completed by stirring and etching at 55-65°C for 1-2 min.

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