JP-7854938-B2 - Semiconductor wafer processing solution containing hypobromite ions and pH buffer.

JP7854938B2JP 7854938 B2JP7854938 B2JP 7854938B2JP-7854938-B2

Inventors

下田享史
吉川由樹
佐藤伴光
根岸貴幸

Assignees

株式会社トクヤマ

Dates

Publication Date: 20260507
Application Date: 20210806
Priority Date: 20200807

Claims (19)

A ruthenium or tungsten etching solution comprising (A), (B), (C), and (E) below, wherein the concentration of (E) bromate ions is 3.3 × 10⁻⁶ mol/L or more and 5.0 × 10⁻¹ mol/L or less. (A) Hypobromite ions (B) pH buffering agent (C) Onium ions (E) Bromate ions
Furthermore, the etching solution according to claim 1, further comprising (D) bromide ions.
The etching solution according to claim 1 or 2, wherein the etching solution further contains an oxidizing agent, and the oxidation-reduction potential of the oxidizing agent exceeds the oxidation-reduction potential of the hypobromite ion/bromide ion system.
The etching solution according to claim 3, wherein the oxidizing agent contained in the etching solution is one or more oxidizing agents selected from the group consisting of hypochlorite ions and ozone.
Furthermore, the etching solution according to any one of claims 1 to 4, comprising (F) one or more chlorine-containing ions selected from the group consisting of chlorite ions, chlorate ions, and chloride ions.
The etching solution according to any one of claims 1 to 5, wherein the hypobromite ion concentration is 0.001 mol/L or more and 0.20 mol/L or less.
The etching solution according to any one of claims 1 to 6, wherein the concentration of the (B) pH buffer is 0.00001 to 1.0 mol/L.
The (B) pH buffering agent is carbonate, boric acid, phosphoric acid, trishydroxymethylaminomethane (tris), ammonia, pyrophosphate, p-phenolsulfonic acid, diethanolamine, ethanolamine, triethanolamine, 5,5-diethylbarbituric acid, glycine, glycylglycine, imidazole, N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid, 3-morpholinopropanesulfonic acid, N-tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid, 2-[4-(2-hydroxyethyl)- The etching solution according to any one of claims 1 to 7, wherein the etching solution is at least one selected from the group consisting of 1-piperazinyl]ethanesulfonic acid, 4-(2-hydroxyethyl)-1-piperazinepropanesulfonic acid, tricine, N,N-di(2-hydroxyethyl)glycine, 2-cyclohexylaminoethanesulfonic acid, hydroxyproline, phenol, and ethylenediaminetetraacetic acid.
The etching solution according to any one of claims 1 to 8, wherein the (C) onium ion is a quaternary ammonium ion or quaternary phosphonium ion represented by the following formula (1), a tertiary ammonium ion or tertiary sulfonium ion represented by the following formula (2), an ammonium ion, pyrrolidinium ion, piperidinium ion, imidazolium ion, or sulfonium ion represented by the following formula (3), or an annium ion or phosphonium ion represented by the following formula (4). (In formula (1), A is nitrogen or phosphorus, and R1 , R2 , R3 , and R4 are independently an alkyl group having 1 to 25 carbon atoms, an allyl group, an aralkyl group which may have substituents on an aryl group, or an aryl group. However, if R1 , R2 , R3 , and R4 are alkyl groups, then at least one of the alkyl groups among R1 , R2 , R3 , and R4 has 2 or more carbon atoms.) In formula (2), A + is nitrogen or sulfur, and R1 , R2 , and R3 are independently an alkyl group having 1 to 25 carbon atoms, an allyl group, an aralkyl group having an alkyl group having 1 to 25 carbon atoms, or an aryl group. However, if R1 , R2 , and R3 are alkyl groups, at least one of the alkyl groups among R1 , R2 , and R3 has 2 or more carbon atoms. Furthermore, the aryl group in the aralkyl group and at least one hydrogen atom in the ring of the aryl group may be replaced with fluorine, chlorine, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 9 carbon atoms, or an alkenyloxy group having 2 to 9 carbon atoms, and in these groups, at least one hydrogen atom may be replaced with fluorine or chlorine. In formula (3), Z is an aromatic group or alicyclic group which may contain nitrogen, sulfur, or oxygen atoms, and in the aromatic group or alicyclic group, at least one hydrogen to which carbon or nitrogen is bonded may be replaced with chlorine, bromine, fluorine, iodine, at least one C1-C15 alkyl group, at least one C2-C9 alkenyloxy group, an aromatic group which may be substituted with at least one C1-C15 alkyl group, or an alicyclic group which may be substituted with at least one C1-C15 alkyl group. A is nitrogen or sulfur. R is chlorine, bromine, fluorine, iodine, a C1-C15 alkyl group, an allyl group, an aromatic group which may be substituted with at least one C1-C15 alkyl group, or an alicyclic group which may be substituted with at least one C1-C15 alkyl group. n is an integer of 1 or 2 and indicates the number of R. When n is 2, R may be the same or different and may form a ring. In formula (4), A is independently nitrogen or sulfur, and R1 , R2, R3 , R4 , R5 , and R6 are independently a C1-C25 alkyl group, an allyl group, an aralkyl group having a C1-C25 alkyl group, or an aryl group. The aryl group in the aralkyl group and at least one hydrogen atom in the ring of the aryl group may be replaced with fluorine, chlorine, a C1-C10 alkyl group, a C2-C10 alkenyl group, a C1-C9 alkoxy group, or a C2-C9 alkenyloxy group, and in these groups, at least one hydrogen atom may be replaced with fluorine or chlorine.
An etching solution according to any one of claims 1 to 9, wherein the pH at 25°C is 8 or higher and 14 or lower.
An etching method comprising the step of bringing an etching solution according to any one of claims 1 to 10 into contact with a semiconductor wafer, wherein the metal on the semiconductor wafer is ruthenium or tungsten.
A RuO4- containing gas generation inhibitor comprising (A), (B), and (C) below, wherein the (C) onium ion comprises a quaternary ammonium ion or a quaternary phosphonium ion represented by the following formula ( 1 ). (A) Hypobromite ions (B) pH buffer (C) Onium ions (In formula (1), A is nitrogen or phosphorus, and R1 , R2 , R3 , and R4 are independently an alkyl group having 1 to 25 carbon atoms, an allyl group, an aralkyl group which may have substituents, or an aryl group. However, if R1 , R2 , R3 , and R4 are alkyl groups, then at least one of the alkyl groups among R1 , R2 , R3 , and R4 has 2 or more carbon atoms.)
Furthermore, the RuO4 -containing gas generation inhibitor according to claim 12, further comprising (D) bromide ions.
Furthermore, the RuO4 -containing gas generation inhibitor according to claim 12 or 13, comprising (E) one or more ions selected from the group consisting of bromite ions and bromate ions.
Furthermore, the RuO4- containing gas generation inhibitor according to any one of claims 12 to 14, comprising (F) one or more chlorine-containing ions selected from the group consisting of chlorite ions, chlorate ions, and chloride ions.
A treatment agent for ruthenium-containing wastewater, comprising (A), (B), and (C) below. (A) Hypobromite ions (B) pH buffer (C) Onium ions
Furthermore, the ruthenium-containing wastewater treatment agent according to claim 16, further comprising (D) bromide ions.
(E) A ruthenium-containing wastewater treatment agent according to claim 16 or 17, comprising one or more ions selected from the group consisting of bromite ions and bromate ions.
Furthermore, the ruthenium-containing wastewater treatment agent according to any one of claims 16 to 18, comprising (F) one or more chlorine-containing ions selected from the group consisting of chlorite ions, chlorate ions, and chloride ions.

Description

This invention relates to a novel processing solution for etching ruthenium present on a semiconductor wafer, used in the manufacturing process of semiconductor devices. In recent years, the miniaturization of semiconductor device design rules has progressed, leading to an increase in wiring resistance. This increased wiring resistance is significantly hindering the high-speed operation of semiconductor devices, necessitating countermeasures. Therefore, wiring materials with improved electromigration resistance and reduced resistance compared to conventional materials are desired. Compared to conventional wiring materials such as aluminum and copper, ruthenium is attracting attention as a wiring material, particularly for semiconductor devices with design rules of 10 nm or less, due to its high resistance to electromigration and its ability to reduce wiring resistance. Furthermore, beyond wiring materials, ruthenium can prevent electromigration even when copper is used as the wiring material, so its use as a barrier metal for copper wiring is also being considered. Incidentally, even when ruthenium is selected as the wiring material in the wiring formation process of semiconductor devices, the wiring is formed by dry or wet etching, similar to conventional wiring materials. However, when performing dry etching of ruthenium, in-plane non-uniformity occurs due to the distribution of plasma, and the etching rate increases or decreases depending on the flux or energy of the reactant species and ions, making precise etching difficult. Therefore, wet etching is attracting attention as a method that can etch ruthenium more precisely. Here, when using ruthenium as a wiring material or barrier metal in ultra-fine fabrication of semiconductor devices with design rules of 10 nm or less, precise processing of the ruthenium is required in wet etching. In other words, if the amount of ruthenium etching is not controlled, other wiring materials may be exposed due to excessive etching of the ruthenium, etc. Furthermore, if multilayer wiring is formed with wiring materials other than ruthenium exposed, current will leak from the exposed wiring materials, and the semiconductor device will not function correctly. Therefore, a semiconductor processing solution that can achieve precise processing of ruthenium is desired. Patent Document 1 proposes an etching solution for semiconductors used to etch ruthenium, characterized in that it is a mixture of a bromine-containing compound, an oxidizing agent, a base compound, and water, wherein the amount of the bromine-containing compound added is 2 to 25% by mass as the amount of bromine element, the amount of the oxidizing agent added is 0.1 to 12% by mass, and the pH is 10 or higher and less than 12. International Publication No. 2011/074601 This is a schematic cross-sectional view showing an example of a wiring formation process in which the processing liquid of the present invention can be suitably used.This is a schematic cross-sectional view showing an example of a wiring formation process after treatment with the processing solution of the present invention. (Processing solution for semiconductors) The processing solution of the present invention is capable of etching ruthenium present on a semiconductor wafer without damaging the semiconductor wafer, and is capable of etching ruthenium at an etching rate with little fluctuation. Therefore, the processing solution of the present invention is suitable for use in the wiring formation process in the semiconductor manufacturing process. The ruthenium to which the processing solution of the present invention is applied may be formed by any method, but for example, in the semiconductor manufacturing process, it is formed on a semiconductor wafer by known methods such as CVD, ALD, and sputtering. By etching the formed ruthenium with the processing solution, semiconductor wiring is formed. In this specification, ruthenium (also written as Ru) is not limited to ruthenium metal, but may contain the element ruthenium. That is, ruthenium metal, ruthenium alloy, ruthenium oxide, etc. are referred to as ruthenium. Figures 1 and 2 show an example of the wiring formation process. An interlayer insulating film 2 made of a silicon oxide film, a low dielectric constant film, etc. is on a lower substrate 1, and a ruthenium film 3 is formed on thereon. By etching the ruthenium as shown in Figure 2, wiring using ruthenium as the wiring material is formed. As described above, the treatment solution of the present invention can be suitably used for etching ruthenium. The treatment solution contains (A) hypobromite ions, (B) a pH buffer, and (C) onium ions. The following is a step-by-step explanation. (A) Hypobromite Ion The hypobromite ion used in the present invention is added to oxidize ruthenium and dissolve it in the treatment solution. The hypobromite ion may be added to the treatment solution by any method, for example, by generating it in the tr