US-12617989-B2 - Abrasive and method for planarization using the same

Abstract

The present invention relates to an abrasive and a planarization method using the same, and more particularly, includes fumed silica. A BET specific surface area of the fumed silica is 200 m 2 /g to 450 m 2 /g, a shape of aggregates dispersed in the abrasive has an elongated shape or a round shape, and a ratio of the round shape of the aggregates is 50% to 90%.

Inventors

• Younghun Park
• Eungchul Kim
• Taesung Kim
• Sangyup LEE
• Kyungyeol Kim
• Hwisu Oh

Assignees

• OCI COMPANY LTD.
• RESEARCH & BUSINESS FOUNDATION SUNGKYUNKWAN UNIVER

Dates

Publication Date

20260505

Application Date

20210115

Priority Date

20200115

Claims (8)

1. 1 . An abrasive for chemical mechanical polishing (CMP) comprising fumed silica, wherein a BET specific surface area of the fumed silica is 200 m 2 /g to 400 m 2 /g, wherein a shape of aggregates of fumed silica dispersed in the abrasive is an elongated shape or a round shape, wherein a ratio of a number of the aggregates having the round shape to a total number of the aggregates is 78% to 80%, and wherein the aggregates are secondary particles formed by disagglomerating tertiary particles of the fumed silica and dispersing them in water.
2. 2 . The abrasive for the CMP of claim 1 , wherein, in the aggregates, the round shape has: an aspect ratio greater than 0.533; and a roundness greater than 0.7 or a solidity greater than 0.76, wherein a given aggregate of the aggregates dispersed in the abrasive has a first length, which is the longest length of the given aggregate in a first direction, and a second length, which is the shortest length of the given aggregate in a second direction intersecting the first direction, and the aspect ratio of the given aggregate is a ratio of the second length to the first length, wherein the given aggregate has a first area two-dimensionally, a circle having the first length as a diameter has a second area, and the roundness of the given aggregate is a ratio of the first area to the second area, and wherein the given aggregate comprises outermost particles of fumed silica, and a third area is defined by a polygon encompassing the given aggregate, the polygon being formed by connecting outermost points on the outermost particles with straight lines in a two-dimensional plane, and the solidity of the given aggregate is a ratio of the first area to the third area.
3. 3 . The abrasive for the CMP of claim 1 , further comprising at least one of a dispersant, a pH adjuster, a surfactant, a viscosity adjuster, and an etchant capable of increasing etch selectivity of the abrasive.
4. 4 . A planarization method comprising: forming a polishing target layer on a wafer; and planarizing the polishing target layer using the abrasive of claim 1 until a surface of the wafer is exposed.
5. 5 . The planarization method of claim 4 , wherein the planarization method is used in a front end of line (FEOL) process in a semiconductor device manufacturing process.
6. 6 . The planarization method of claim 4 , wherein the planarizing of the polishing target layer includes: performing a first planarization process on the polishing target layer using a first abrasive; and performing a second planarization process using a second abrasive on the polishing target layer, and wherein the first abrasive includes fumed silica having a BET specific surface area of 1 m 2 /g to 150 m 2 /g, and wherein the second abrasive is the abrasive of claim 1 .
7. 7 . The planarization method of claim 6 , wherein the first planarization process is performed until a surface of the polishing target layer reaches a predetermined distance from the surface of the wafer, and wherein the second planarization process is performed until the surface of the wafer is exposed.
8. 8 . The planarization method of claim 4 , further comprising forming a trench defining an active area on the wafer, and wherein the polishing target layer fills the trench.

Description

RELATED APPLICATIONS This application is a § 371 National Phase Application of International Application No. PCT/KR2021/000633, filed on Jan. 15, 2021, now International Publication No. WO 2021/145739 A1, published on Jul. 22, 2021, which International Application claims priority to Korean Application 10-2020-0005624, filed on Jan. 15, 2020, both of which are incorporated herein by reference in their entirety. TECHNICAL FIELD The present invention relates to an abrasive and a planarization method using the same, and more particularly, relates to an abrasive for a CMP and a planarization method using the same. BACKGROUND ART High integration of a semiconductor device progresses yearly. Accordingly, in a manufacturing process of the semiconductor device, quality required for a surface of each layer becomes stricter year by year. In accordance with this requirement, in a chemical mechanical polishing method (hereinafter, CMP), which is a semiconductor surface processing technology, for a polishing object, it is required that the CMP has less contamination, less scratches, high material removal rate, and high selectivity for a target object to be polished. In general, silica, cerium oxide, or the like is used as abrasive particles for the CMP. Fumed silica may form secondary particles by strongly aggregating primary particles with one another by fusion. The secondary particles may slightly aggregate with one another to form tertiary particles. In general, fumed silica in a powder state may exist as the tertiary particles. DISCLOSURE OF THE INVENTION Technical Problem The present invention provides an abrasive including fumed silica for a CMP. The present invention provides a planarization method using the abrasive. Technical Solution An abrasive for a CMP according to the inventive concept of the present invention may include fumed silica. A BET specific surface area of the fumed silica may be 200 m2/g to 450 m2/g, a shape of aggregates dispersed in the abrasive may have an elongated shape or a round shape, and a ratio of the round shape of the aggregates may be 50% to 90%. A planarization method according to the inventive concept of the present invention may include forming a polishing object layer on a wafer and planarizing a polishing target layer using the abrasive until a surface of the wafer is exposed. Advantageous Effects The abrasive according to the present invention may include the fumed silica having a relatively large specific surface area and consisting of round-shaped aggregates. Accordingly, while maintaining an excellent material removal rate, a surface roughness of a polishing target may be lowered. The abrasive according to the present invention may prevent damage to a wafer surface, and thus may be effectively applied to a front end of line (FEOL) process during a manufacturing process of a semiconductor device. BRIEF DESCRIPTION OF IDE DRAWINGS FIG. 1 is a schematic diagram for illustrating particles of fumed silica; FIG. 2 is a conceptual diagram for illustrating an abrasive according to embodiments of the present invention; FIG. 3 is a flowchart for illustrating a method for separating and collecting single aggregates from fumed silica according to embodiments of the present invention; FIG. 4 is a conceptual diagram for illustrating forming a slurry from fumed silica; FIG. 5 is a conceptual diagram for illustrating collecting single aggregates of fumed silica in an aerosol; FIGS. 6A to 6D are images each illustrating single aggregates having various shapes; FIG. 7 is an algorithm for classifying a shape of single aggregates according to embodiments of the present invention; FIG. 8 is a conceptual diagram for illustrating an aspect ratio of single aggregates; FIG. 9 is a conceptual diagram for illustrating a roundness of single aggregates; FIG. 10 is a conceptual diagram for illustrating a solidity of single aggregates; FIG. 11 is a graph illustrating a material removal rate of an abrasive according to Examples of the present invention and Comparative Examples; FIG. 12 is a graph illustrating a surface roughness of a polishing target of an abrasive according to Examples of the present invention and Comparative Examples; and FIGS. 13 to 16 are cross-sectional views for illustrating a CMP process on a wafer according to embodiments of the present invention. MODE FOR CARRYING OUT THE INVENTION In order to facilitate sufficient understanding of the configuration and effects of the present invention, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments set forth below, and may be embodied in various forms and modified in many alternate forms. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art to which the present invention pertains. The terms used h