InP Dry Etching Process (RIE or ICP-RIE)

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Material Properties and Applications of Indium Phosphide (InP)

Indium Phosphide (InP) is a compound semiconductor material of III-V group.  This material has a wide band gap and a high electron mobility.

• Band Gap : 1.35 eV (300K) (1.2 times that of Si)
• Electron Mobility : 5,400 cm2/Vs (300K) (3.6 times that of Si)

Also, this material has large lattice constant of 5.8687 A. Therefore, InP-based alloys such as InGaAs, AlInAs, InGaAsP and AlGaInAs are grown on the InP substrate without lattice mismatches. 

Indium Phosphide (Periodic Table)

One of the applications of InP is photonic devices including laser diodes (LDs), photodiodes and waveguides. InP-based photonic devices have contributed to high-speed data transfer with less energy consumption at data centers.

Another application of InP is radio-frequency (RF) and microwave devices including power amplifiers. Low-noise, high-speed and low-DC power consumption devices are manufactured using InP substrates for military and telecommunication.

InP Pillar Etching with Vertical Sidewalls

InP pillar structures are used for various applications such as laser diodes and solar cells. There are top-down and bottom-up approaches to fabricate the nanopillar structures. The top-down approach using plasma etching technology offers uniform and precisely controlled structures. However, insufficient understanding of InP plasma etch chemistry causes pillar profile with rounded sidewalls. The rounded sidewalls are not preferable for laser diode fabrication because they deteriorate optical properties of light extraction and absorption. Therefore, there are process challenges in sidewall angle control as well as surface roughness control (RMS roughness) on InP etching.

To provide a process solution of InP pillar etching, Samco has developed etch recipes with optimized equipment configuration. As a result of process and hardware development, InP pillars with vertical and straight sidewalls were fabricated. The sidewall profile was highly straight and no distortion was seen. This sidewall profile is promising for InP-based laser diode with excellent optical properties.

Samco possesses experienced process knowledge of InP plasma etching. We will optimize and offer InP etching processes based on customers’ process demands on etching profile (shape and geometry).

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InP Pillar Etching with Vertical and Straight Sidewalls
inp pillar etching for laser diode

InP arrays were fabricated for surface emitting laser diode fabrication.
Etch Rate : 920 nm/min
Data courtesy of University of Delaware

InP arrays fabrication

InP Ridge Etching

The etched profile shows vertical sidewalls. This process is used for InP waveguide fabrication.

Etch Rate : 350 nm/min
Etch Mask : Oxide

InP Anisotropic Etching for Waveguide Fabrication
InP Anisotropic Etching for Waveguide Fabrication

The etched profile shows vertical sidewalls. This process is used for InP waveguide fabrication.
Etch Depth : 2.83 µm
Etch Rate : 565 nm/min
Sidewall Angle : 88°
Etch Selectivity : 15.5 (over SiN mask)

Anisotropic InP Etching
InP Etching with Vertical Sidewalls

InP Grating Etching

InP plasma etching over SiO2 mask was performed using an ICP-RIE etcher for grating fabrication.
Vertical profile was achieved, and etching rate was 50 nm/min.
mask width: 100 nm
mask depth: 75 nm

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InP grating by plasma etching

InP Photonic Crystal Fabrication

Fabrication of InP photonic crystal laser was performed using SAMCO ICP Etch System. A periodic pattern of holes (<0.3 µm diameter, ~1 µm deep) was successfully fabricated.

The hole patterns work as a ring-shaped defect, and light is forcefully trapped in the defect area, generating laser oscillation.

Data courtesy of Baba Lab, Yokohama National University

 

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Indium Phosphide Photonic Crystal

InP Via Hole Etching

Etch Depth : 74.4 µm
Etch Rate : 4.96 µm/min
Etch Selectivity : 200 (over Ni mask)

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InP via hole etching
InP via hole fabrication

InP Lens Fabrication

Round-shape InP lens structure was fabricated using chlorine chemistry.

Etch Selectivity : 1.1 (over photoresist)

 

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InP Lens Etching
InP Lens Fabrication

System Lineup for InP Plasma Etching

RIE Systems

– Excellent InP etch uniformity over the wafers
– Optional optical/Interferometric end-point detection
– Easy-to-use touch-panel GUI


RIE System for InP Plasma Etching

 

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ICP Etch Systems

– ICP plasma sources optimizing GaN etch profile control
– Optional optical/Interferometric end-point detection
– Easy-to-use touch-panel GUI


ICP Etch Systems for InP Plasma Etching

 

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  • SAMCO System for InP Etch

Testimonial

 SAMCO’s InP etching technologies are used for R&D and production of photonic devices and RF devices at facilities including

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