Etching characteristics and application of physical-vapor-deposited amorphous carbon for multilevel resist

Abstract

For the fabrication of a multilevel resist (MLR) based on a very thin, physical-vapor-deposited (PVD) amorphous carbon (a-C) layer, the etching characteristics of the PVD a-C layer with a SiOx hard mask were investigated in a dual-frequency superimposed capacitively coupled plasma etcher by varying the following process parameters in O2∕N2∕Ar plasmas: high-frequency/low-frequency combination (fHF∕fLF), HF/LF power ratio (PHF∕PLF), and O2 and N2 flow rates. The very thin nature of the a-C layer helps to keep the aspect ratio of the etched features low. The etch rate of the PVD a-C layer increased with decreasing fHF∕fLF combination and increasing PLF and was initially increased but then decreased with increasing N2 flow rate in O2∕N2∕Ar plasmas. The application of a 30nm PVD a-C layer in the MLR structure of ArF PR∕BARC∕SiOx∕PVD a-C∕TEOS oxide supported the possibility of using a very thin PVD a-C layer as an etch-mask layer for the TEOS-oxide layer.

Inductively Coupled Plasma Etching of Chemical-Vapor-Deposited Amorphous Carbon in N2/O2/Ar Chemistries

“…The SiO x hard mask was etched in the C 4 F 8 (20 sccm)/CH 2 F 2 (15 sccm)/O 2 (15 sccm)/ Ar (300 sccm) plasmas for 60 s at high-frequency (27.12 MHz) and low-frequency (2 MHz) power sources of 600 and 300 W, respectively. 6) The samples with patterned SiO x mask were fixed on an 8-in. silicon wafer placed on the substrate holder using a heat-conductive paste, DC 340 (Dow Corning).…”

“…1,2) CVD a-C has several potential applications, particularly in the microelectronics industry, because of its optical, electrical and mechanical properties. [3][4][5][6] Such a-C films can be obtained by several techniques, such as laser evaporation, ion beam and plasma deposition. [7][8][9] The a-C has extremely high hardness, high melting temperature, good wear resistance, outstanding chemical inertness, and good corrosion resistance.…”

“…Furthermore, only a few reports on the etch characteristics of a-C layers for MLR have been published. 1,2,6,12) In this work, a CVD a-C thin film layer, synthesized by RF plasma enhanced CVD (PECVD) method with methane (CH 4 ) and hydrogen (H 2 ) gases, was etched and its etch characteristics and the etch mechanism of the CVD a-C films were investigated using O 2 /N 2 /Ar inductively coupled plasmas (ICPs) at various gas flow ratios and plasma powers. Experimental results indicated that the etch rate and profile angle were decreased with increasing N 2 flow rate due to the increased formation of CN x phase on the a-C surface.…”

Role of Oxygen in Amorphous Carbon Hard Mask Plasma Etching

“…The application of amorphous carbon as an alternative hard mask for conductive or dielectric underlayer HAR etching has been introduced as a means of addressing the limitations associated with conventional single-layer hard masks based on silicon. − The utilization of an amorphous carbon layer (ACL) as an etching mask in nanoscale plasma etching patterning is facilitated by its impressive physical properties, including a high melting point, exceptional hardness, and resistance to corrosion and etching in Cl- or F-containing gases. Additionally, in both current and next-generation semiconductor processing, the ACL hard mask, in conjunction with a complex gas mixed plasma, can be leveraged to achieve high etching selectivity in HAR etching. − In industrial semiconductor plasma etching, three or more complex gas mixtures, which are based on inert gases such as argon and composed of a combination of oxygen, C x F y , and C x H y F z gases, are used to control the etch profile and selectivity. , In a complex gas mixture, inert gas is injected to control the plasma density and degree of dissociation rate, and a trace amount of oxygen gas is injected to control the degree of precursors and deposited polymers produced in the plasma. , However, the high removability of the ACL by oxygen can result in unwanted sidewall etching of the ACL hard mask when exposed to a processing plasma containing oxygen gas, leading to a distorted etch profile and increased pattern opening.…”

Study on the etching characteristics of amorphous carbon layer in oxygen plasma with carbonyl sulfide

“…8 In addition, in the case of the aliphatic photoresist, the patterned photoresist is easily deformed during the extended exposure to plasma due to the its softness, creating problems such as wiggling and notching. [11][12][13][14][15] Among the various hardmask materials, the ACL has been investigated widely due to its advantages such as a high etch selectivity over a photoresist, high optical transmittance, easy deposition, and removability by oxygen plasma, similar to that of a remaining photoresist, after etching. [11][12][13][14][15] Among the various hardmask materials, the ACL has been investigated widely due to its advantages such as a high etch selectivity over a photoresist, high optical transmittance, easy deposition, and removability by oxygen plasma, similar to that of a remaining photoresist, after etching.…”