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US-12624286-B2 - Etching composition, etching method, method for manufacturing semiconductor device, and method for manufacturing gate-all-around-type transistor

US12624286B2US 12624286 B2US12624286 B2US 12624286B2US-12624286-B2

Abstract

An etching composition that includes a quaternary ammonium salt having 8 or more carbon atoms and selectively dissolves silicon over silicon germanium, and may further include a chelating agent, an etching method comprising etching a structure that contains silicon and silicon germanium by using the etching composition, a method for manufacturing a semiconductor device, and a method for manufacturing a gate-all-around-type transistor using the etching composition.

Inventors

  • Ken Harada
  • Tatsunobu Suzuki
  • Mari Abe

Assignees

  • MITSUBISHI CHEMICAL CORPORATION

Dates

Publication Date
20260512
Application Date
20230707
Priority Date
20210112

Claims (14)

  1. 1 . An etching composition comprising a quaternary ammonium salt having 8 or more carbon atoms and a water-miscible solvent, wherein a mass ratio of the quaternary ammonium salt having 8 or more carbon atoms to the water-miscible solvent is greater than or equal to 1, and the etching composition selectively dissolves silicon over silicon germanium.
  2. 2 . The etching composition according to claim 1 , wherein the quaternary ammonium salt having 8 or more carbon atoms contains at least one compound selected from the group consisting of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrahexylammonium hydroxide, tetraoctylammonium hydroxide, and benzyltrimethylammonium hydroxide.
  3. 3 . The etching composition according to claim 1 , wherein the quaternary ammonium salt having 8 or more carbon atoms contains at least one compound selected from the group consisting of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide.
  4. 4 . The etching composition according to claim 1 , wherein the quaternary ammonium salt having 8 or more carbon atoms includes 50 mass % or more of a quaternary alkyl ammonium salt having four identical alkyl groups based on a total mass of the quaternary ammonium salt having 8 or more carbon atoms.
  5. 5 . The etching composition according to claim 1 , wherein a content of the quaternary ammonium salt having 8 or more carbon atoms is greater than or equal to 10 mass % based on a total mass of the etching composition.
  6. 6 . The etching composition according to claim 1 , further comprising a chelating agent.
  7. 7 . The etching composition according to claim 6 , wherein a content of the chelating agent is 0.001 mass % to 25 mass % based on a total mass of the etching composition.
  8. 8 . The etching composition according to claim 6 , wherein a mass ratio of the quaternary ammonium salt having 8 or more carbon atoms to the chelating agent is 5 to 5000.
  9. 9 . The etching composition according to claim 1 , further comprising water.
  10. 10 . The etching composition according to claim 1 , wherein a content of the water-miscible solvent is less than or equal to 15 mass % based on a total mass of the etching composition.
  11. 11 . An etching composition comprising a quaternary ammonium salt having 8 or more carbon atoms and a water-miscible solvent, wherein the quaternary ammonium salt having 8 or more carbon atoms contains at least one compound selected from the group consisting of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide, the quaternary ammonium salt having 8 or more carbon atoms includes 50 mass % or more of a quaternary alkyl ammonium salt having four identical alkyl groups based on a total mass of the quaternary ammonium salt having 8 or more carbon atoms, and a content of the quaternary ammonium salt having 8 or more carbon atoms is greater than or equal to 10 mass % based on a total mass of the composition, wherein a mass ratio of the quaternary ammonium salt having 8 or more carbon atoms to the water-miscible solvent is greater than or equal to 1.
  12. 12 . An etching method comprising etching a structure that contains silicon and silicon germanium by using the etching composition according to claim 1 .
  13. 13 . A method for manufacturing a semiconductor device comprising etching a structure containing silicon and silicon germanium by using the etching composition according to claim 1 .
  14. 14 . A method for manufacturing a gate-all-around transistor comprising etching a structure containing silicon and silicon germanium by using the etching composition according to claim 1 .

Description

TECHNICAL FIELD The present invention relates to etching compositions, an etching method, a method for manufacturing a semiconductor device, and a method for manufacturing a gate-all-around-type transistor. BACKGROUND ART Integrated circuits are increasingly scaled down according to Moore's law. In recent years, studies have been conducted to improve performance and advance further scaling-down and integration not only by reducing the size of the conventional planar transistors but also by modifying structures; examples of such modifications include fin-type transistors (fin-type FET) and gate-all-around-type transistors (GAA-type FET). In fin-type FETs, fins are formed on a silicon substrate in a vertical direction. Accordingly, fin-type FETs have an increased number of transistors per unit area and, in addition, exhibit excellent performance in ON/OFF control at low voltage. Further improving the performance would require an alteration, such as an increase in an aspect ratio of the fins. However, if the aspect ratio is excessively high, problems arise, such as a collapse of the fins in a cleaning process or a drying process used for the formation of the fins. In GAA-type FETs, the performance of the transistors per unit area is improved by covering a nanosheet or a nanowire, which serves as a channel, with a gate electrode, thereby increasing an area of contact between the channel and the gate electrode. The formation of GAA-type FETs requires an etching composition for selectively etching silicon or silicon germanium from a structure in which silicon and silicon germanium are alternately layered. Patent Literature 1 discloses such an etching composition, which is a composition containing a quaternary ammonium hydroxide compound, specifically, ethyltrimethylammonium hydroxide. PTL 1: JP 2019-050364 A The etching composition disclosed in Patent Literature 1 is one in which the type of the quaternary ammonium hydroxide compound is not optimized, and a chelating agent is not included. For either of these reasons, it cannot be said that the etching composition has sufficient ability to selectively dissolve silicon over silicon germanium. In the structure disclosed in Patent Literature 1 in which silicon and silicon germanium are alternately layered, the silicon used is polysilicon, which has low crystallinity. It is, therefore, unknown whether a comparable selective dissolution ability can be provided in the case of high-crystallinity silicon, which is used in actual semiconductor devices in many cases. To date, etching compositions containing various components have been studied as in Patent Literature 1. Unfortunately, it cannot be said that those compositions have had sufficient ability to selectively dissolve silicon over silicon germanium. SUMMARY OF INVENTION An object of the present invention is to provide etching compositions that promote dissolution of silicon while inhibiting dissolution of silicon germanium and, therefore, have an enhanced ability to selectively dissolve silicon over silicon germanium. Another object of the present invention is to provide an etching method, a method for manufacturing a semiconductor device, and a method for manufacturing a gate-all-around-type transistor; these methods use any of the etching compositions. Solution to Problem The inventors of the present invention found that the later-described etching compositions promote dissolution of silicon while inhibiting dissolution of silicon germanium and, therefore, have an enhanced ability to selectively dissolve silicon over silicon germanium. Accordingly, the features of the present invention are as follows: [1] An etching composition comprising a quaternary ammonium salt having 8 or more carbon atoms, wherein the etching composition selectively dissolves silicon over silicon germanium.[2] The etching composition according to [1], wherein the quaternary ammonium salt having 8 or more carbon atoms contains at least one compound selected from the group consisting of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrahexylammonium hydroxide, tetraoctylammonium hydroxide, and benzyltrimethylammonium hydroxide.[3] The etching composition according to [1], wherein the quaternary ammonium salt having 8 or more carbon atoms contains at least one compound selected from the group consisting of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide.[4] The etching composition according to [1], wherein the quaternary ammonium salt having 8 or more carbon atoms includes 50 mass % or more of a quaternary alkyl ammonium salt having four identical alkyl groups based on a total mass of the quaternary ammonium salt having 8 or more carbon atoms.[5] The etching composition according to [1], wherein a content of the quaternary ammonium salt having 8 or more carbon atoms is greater than or equal to 10 mass % based on a total mass of the etching composition.