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JP-2026075073-A - Etching method

JP2026075073AJP 2026075073 AJP2026075073 AJP 2026075073AJP-2026075073-A

Abstract

[Problem] In one embodiment, the present disclosure provides an etching method that can suppress the increase in etching rate due to an increase in the amount of water in the etching solution. [Solution] In one embodiment, the present disclosure relates to an etching method for etching a layer to be etched containing molybdenum, comprising the following steps 1 and 2. Step 1: The etching solution containing nitric acid and phosphoric acid is brought into contact with the layer to be etched, which contains molybdenum. Step 2: Acid anhydride is added to the etching solution after Step 1. [Selected Figure] None

Inventors

  • 前田 尚也
  • 内田 洋平

Assignees

  • 花王株式会社

Dates

Publication Date
20260507
Application Date
20251017
Priority Date
20241021

Claims (15)

  1. An etching method for etching a layer to be etched containing molybdenum, An etching method comprising the following steps 1 and 2. Step 1: A step in which an etching solution containing nitric acid and phosphoric acid is brought into contact with the layer to be etched, which contains molybdenum. Step 2: A step in which anhydrous acid is added to the etching solution after Step 1.
  2. The etching method according to claim 1, wherein the etching solution used in step 1 further comprises an organic acid (excluding anhydride).
  3. The etching method according to claim 1, wherein the acid anhydride added in step 2 is acetic anhydride.
  4. The etching method according to claim 2, wherein the mass ratio (organic acid/nitric acid) of the etching solution used in step 1 is 5 or more and 50 or less.
  5. The etching method according to claim 2, wherein the mass ratio (organic acid/phosphoric acid) of the etching solution used in step 1 is 3 or more and 20 or less.
  6. The etching method according to claim 1, wherein the mass ratio (nitric acid/phosphoric acid) of the etching solution used in step 1 is 0.1 or more and 2.0 or less.
  7. The etching method according to claim 1, wherein the amount of nitric acid in the etching solution used in step 1 is 0.5% by mass or more and 10% by mass or less.
  8. The etching method according to claim 1, wherein the amount of phosphoric acid in the etching solution used in step 1 is 1% by mass or more and 70% by mass or less.
  9. The etching method according to claim 2, wherein the amount of organic acid in the etching solution used in step 1 is 10% by mass or more.
  10. The etching method according to claim 1, wherein the amount of water in the etching solution used in step 1 is 15% by mass or less.
  11. The etching method according to claim 1, wherein the amount of acid anhydride added in step 2 is 0.1% by mass or more and 65% by mass or less relative to the total amount of etching solution.
  12. The etching method according to claim 1, wherein the etching solution containing nitric acid and phosphoric acid that is brought into contact with the molybdenum-containing layer to be etched in step 1 includes the etching solution after step 2.
  13. The etching method according to claim 1, wherein the difference between the etching rate in step 1 and the etching rate using the etching solution obtained after step 2 is within 10%.
  14. The etching method according to claim 1, wherein step 2 includes measuring the amount of water in the etching solution after step 1.
  15. A method for manufacturing a semiconductor wafer, comprising the etching method described in any one of claims 1 to 14.

Description

This disclosure relates to an etching method for etching a molybdenum-containing layer. In the manufacturing process of semiconductor devices, for example, a step is taken to etch a layer containing at least one metal such as tungsten, tantalum, zirconium, hafnium, molybdenum, niobium, ruthenium, osmium, rhenium, rhodium, copper, nickel, cobalt, titanium, aluminum, and iridium, or its nitride or oxide, by etching it into a predetermined pattern shape. In recent years, the semiconductor field has seen increasing integration, leading to a demand for more complex and miniaturized wiring. This has resulted in growing demands for pattern processing technologies and etching solutions, and various etching methods and solutions have been proposed. For example, Patent Document 1 proposes an etching solution comprising at least nitric acid, acetic acid, a phosphorus compound, and water, with a water concentration of 3.0 M or less after mixing. The same document states that an acid anhydride may be further added to the etching solution. Japanese Patent Publication No. 2023-112748 As a result of diligent research by the present inventors, it was found that by adding anhydrous acid to the etching solution used for etching, the amount of water in the etching solution can be reduced, thereby suppressing the difference in etching rate between the etching rate when the etching solution is reused and the etching rate when it is used for the first time. In other words, it is possible to suppress the increase in etching rate due to an increase in the amount of water in the etching solution. Although Patent Document 1 describes the addition of anhydrous acid during the preparation of the etching solution, anhydrous acid reacts with nitric acid in the etching solution. Therefore, it is difficult to add a large amount of anhydrous acid to the etching solution for the first time, and it is difficult to suppress the increase in water content when the etching solution is used repeatedly. In other words, in one embodiment, this disclosure relates to an etching method for etching a molybdenum-containing layer to be etched, comprising the following steps 1 and 2 (hereinafter also referred to as "the etching method of this disclosure"). Step 1: A step in which an etching solution containing nitric acid and phosphoric acid is brought into contact with the layer to be etched, which contains molybdenum. Step 2: A step in which anhydrous acid is added to the etching solution after Step 1. The etching method of this disclosure makes it possible to suppress the increase in etching rate caused by an increase in the water content in the etching solution. [Etched layer] In one or more embodiments, the layer to be etched using the etching method of this disclosure is a layer to be etched containing molybdenum. In one or more embodiments, the layer to be etched containing molybdenum may consist of molybdenum, or in one or more other embodiments, it may contain molybdenum and a metal other than molybdenum. Examples of metals other than molybdenum include at least one metal selected from tungsten, tantalum, zirconium, hafnium, niobium, ruthenium, osmium, rhenium, rhodium, copper, nickel, cobalt, titanium, aluminum, and iridium, or a nitride thereof, or an oxide thereof. [Step 1: Etching] Step 1 is, in one or more embodiments, a step (etching step) in which an etching solution containing nitric acid and phosphoric acid is brought into contact with a layer to be etched containing molybdenum (hereinafter also simply referred to as the "layer to be etched"). In step 1, examples of methods for bringing the etching solution into contact with the layer to be etched include immersion etching and single-wafer etching. In one or more embodiments, the etching solution may be stirred or circulated when it comes into contact with the layer to be etched. Examples of stirring methods include using a propeller-type stirrer, and examples of liquid circulation methods include circulating the liquid using a pump (a method of stirring without using stirring blades). The stirring speed can be set appropriately, but from the viewpoint of improving uniform etching in the plane, 50 rpm or more is preferred, 100 rpm or more is more preferred, and 200 rpm or more is even more preferred. The liquid circulation speed can be set appropriately, but from the viewpoint of improving uniform etching in the plane, 1 L/min or more is preferred. The etching solution temperature in step 1 (etching temperature) is preferably 0°C or higher, more preferably 15°C or higher, even more preferably 20°C or higher, preferably 80°C or lower, more preferably 65°C or lower, and even more preferably 50°C or lower, from the viewpoint of uniform etching of the layer to be etched. More specifically, in one or more embodiments, the etching temperature is preferably 0°C or higher and 80°C or lower, more preferably 15°C or higher and 65°C or lower, and even more preferably 20°C or higher and 50°C or lower