US-12628593-B2 - Method for treating transition metal semiconductor, and reducing agent-containing treatment liquid for transition metal oxide

US12628593B2US 12628593 B2US12628593 B2US 12628593B2US-12628593-B2

Abstract

The present invention addresses the issue of providing a method for removing a transition metal oxide adhered to a transition metal film in a process for manufacturing a semiconductor element, and of providing a treatment liquid. Specifically, the present invention provides a method for treating a semiconductor of a transition metal, the method including, in a semiconductor formation process, a step of removing a transition metal oxide and a step of removing the transition metal. The present invention also provides a reducing agent-containing treatment liquid for a transition metal oxide, wherein the concentration of the reducing agent contained in the reducing agent-containing treatment liquid is 0.01 mass % or more and 50 mass % or less.

Inventors

Kohei Saito
Tomoaki Sato
Yuki Kikkawa
Takafumi Shimoda
Takayuki Negishi

Assignees

TOKUYAMA CORPORATION

Dates

Publication Date: 20260512
Application Date: 20211213
Priority Date: 20201218

Claims (12)

1 . A method for treating a semiconductor of a transition metal, the method comprising: a step of removing a transition metal oxide; and a step of removing the transition metal; wherein the step of removing the transition metal oxide is a step of removing the transition metal oxide using a reducing agent-containing treatment liquid, an alkaline solution, or sputtering; and the step of removing the transition metal is carried out by wet etching; and a treatment liquid used in the wet etching is a solution containing a halogen oxyacid ion and not containing a reducing agent.
2 . The method for treating a semiconductor of a transition metal according to claim 1 , the method comprising the step of removing the transition metal oxide a plurality of times.
3 . The method for treating a semiconductor of a transition metal according to claim 1 , the method comprising the step of removing the transition metal a plurality of times.
4 . The method for treating a semiconductor of a transition metal according to claim 1 , wherein a concentration of a reducing agent contained in the reducing agent-containing treatment liquid is 0.1 mass % or more and 15 mass % or less.
5 . The method for treating a semiconductor of a transition metal according to claim 1 , wherein the reducing agent of the reducing agent-containing treatment liquid is a borohydride compound, hydrogen, a tin (II) compound, an iodide, sulfurous acid, a sulfite, hypophosphorous acid, or a hypophosphite.
6 . The method for treating a semiconductor of a transition metal according to claim 1 , wherein a concentration of an alkali contained in the alkaline solution is 0.05 mol/L or more and 15 mol/L or less.
7 . The method for treating a semiconductor of a transition metal according to claim 1 , wherein the alkali of the alkaline solution is an alkali metal hydroxide, an alkali metal carbonate, an alkali metal hydrogen carbonate, an alkaline earth metal hydroxide, an alkaline earth metal carbonate, an alkaline earth metal hydrogen carbonate, ammonia, ammonium carbonate, an amine, or an alkylammonium hydroxide.
8 . The method for treating a semiconductor of a transition metal according to claim 7 , wherein a concentration of the alkali metal hydroxide contained in the alkaline solution of the alkali metal hydroxide is 0.05 mol/L or more and 5 mol/L or less.
9 . The method for treating a semiconductor of a transition metal according to claim 7 , wherein a concentration of ammonia contained in the alkaline solution of ammonia is 3 mol/L or more and 15 mol/L or less.
10 . The method for treating a semiconductor of a transition metal according to claim 7 , wherein a concentration of the alkylammonium hydroxide contained in the alkaline solution of the alkylammonium hydroxide is 0.05 mol/L or more and 3 mol/L or less.
11 . The method for treating a semiconductor of a transition metal according to claim 1 , wherein the transition metal is Ru, Rh, Co, Cu, Mo, or W.
12 . A method for manufacturing a semiconductor of a transition metal, the method comprising the method for treating a semiconductor of a transition metal according to claim 1 .

Description

TECHNICAL FIELD The present invention relates to a method for treating a semiconductor of a transition metal, the method including a step of removing a transition metal oxide. The present invention also relates to a reducing agent-containing treatment liquid for a transition metal oxide. BACKGROUND ART In recent years, design rules for semiconductor elements have advanced in a direction of further miniaturization, and in association therewith, there has been a tendency for an increase in wiring resistance. A hindrance in high-speed operation of semiconductor elements as a result of this increase in wiring resistance has become obvious, and thus countermeasures have become necessary. Therefore, as wiring materials, a wiring material having higher electromigration resistance than known wiring materials, and a wiring material with a reduced resistance value are desired. In comparison to the known wiring materials of aluminum and copper, ruthenium exhibits higher electromigration resistance and can reduce the resistance value of wiring, and for this reason, ruthenium is attracting attention particularly as a wiring material for semiconductor elements based on a design rule of 10 nm or less. Ruthenium can prevent electromigration of copper even when copper is used as the wiring material, and therefore the use of ruthenium as a barrier metal for copper wiring is also being examined in addition to its use as a wiring material. Incidentally, even when ruthenium is selected as a wiring material in a wiring formation process of a semiconductor element, the wiring is formed on a semiconductor wafer by dry or wet etching, similar to known wiring materials. However, since it is difficult to etch and remove ruthenium by dry etching using an etching gas or by CMP polishing, more precise etching is desired, and specifically, wet etching is attracting attention. When ruthenium is wet etched, the dissolution rate of the ruthenium, that is, the etching rate, is important. When the etching rate is high, ruthenium can be dissolved in a short amount of time, and thus the number of wafers treated per unit time can be increased. As a result, an improvement in productivity can be expected. When ruthenium is wet etched, the surface of ruthenium after etching is required to flat. When the ruthenium surface is not flat, the flatness of the material formed on the ruthenium layer becomes poor, which causes a decrease in processing accuracy and a decrease in yield when manufacturing semiconductor elements. Further, when ruthenium is used as a wiring material, if the flatness of the ruthenium is reduced, its contact resistance with other wiring materials increases, resulting in a decrease in performance of the semiconductor element. In particular, with the advancement of miniaturization of wiring, flatness is strongly required in an etchback step (recess step) when forming multilayer wiring. For these reasons, a wet etching method having a high etching rate and providing excellent flatness of ruthenium is demanded. Generally, a natural oxide layer is rapidly formed on a transition metal surface after film formation. When a wafer containing a transition metal is subjected to a CMP treatment, the transition metal is oxidized by an oxidizing agent contained in the CMP slurry, and a transition metal oxide is formed. Various liquids have been proposed as treatment liquids used for wet etching a metal such as ruthenium in a semiconductor wafer. For example, Patent Document 1 proposes, as a method for etching a ruthenium film, a method in which a ruthenium film is etched using a chemical solution having a of 12 or higher and a standard oxidation-reduction potential of 300 mV vs. SHE (standard hydrogen electrode) or higher, more specifically, a solution containing an oxyacid salt of a halogen, such as a hypochlorite, a chlorite, or a bromate. Patent Document 2 proposes a cleaning method in which ruthenium is oxidized, dissolved, and removed using a removing solution obtained by adding a strong acid such as nitric acid to cerium (IV) ammonium nitrate. Patent Document 3 proposes, as a treatment liquid for etching a metal in a semiconductor wafer, a wafer treatment liquid containing hypochlorite ions and a solvent, and having a pH of higher than 7 and lower than 12.0 at 25° C. PRIOR ART DOCUMENTS Patent Documents Patent Document 1: JP 2002-161381 APatent Document 2: JP 2001-234373 APatent Document 3: WO 2019/142788 SUMMARY OF INVENTION Technical Problem When a transition metal is to be etched from a semiconductor wafer containing the transition metal, a high etching rate and excellent flatness of the transition metal are important. However, a study by the present inventors revealed that the existing treatment liquids described in the prior art documents have room for improvement in terms of the following. The etchback step mentioned above requires accurate control of the etching rate on the surface to be treated. Specifically, surface roughness on t