Tomohiro Kawase

Chapter 5 InP Substrates: Production and Quality Control

Publisher Summary This chapter presents a discussion on the production and quality control of indium phosphide (InP) substrates. It describes the techniques related to InP single crystal materials and their characterization. The applications of InP crystals and the requirements for their quality is described in the chapter. The chapter reviews the details of crystal growth techniques, including recent developments obtained in laboratories. The techniques used in the evaluation, quality control, and wafer processing are also described in the chapter. InP single crystals have been used exclusively as conductive substrates for infrared optical devices. They are also under development as semi-insulating substrates usable in higher frequency microwave devices, such as metal–insulator–semiconductor field-effect transistor (MISFETs) and optoelectronic integrated circuits. There is a great demand for the development of higher quality indium phosphide single crystals. For this purpose, the technologies reviewed in the chapter, especially those concerning both the crystal growth and the processing of this material, are very important for future developments. Etch-pit density (EPD) is one of the best indicators of the quality of II–-V semiconductor crystals.

Improvement of microscopic and macroscopic uniformity in 4-inch InP substrate for IC application by vertical boat growth

Macroscopic and microscopic uniformity in 4-inch InP substrates has been significantly improved by new developments in SEIs Vertical Boat (VB) technique. In this paper, we report improvements, in etch-pit density (EPD) distribution, micro-resistivity profiles, and photoluminescence (intensity and 4.2K spectra), for 4-inch InP VB in comparison to both VCZ (SEI proprietary Vapor pressure controlled Chockralski) and commercially available VGF substrates.

Preparation of n-type InP substrates by Vertical Boat growth

N-type InP substrates have been manufactured using Vertical Boat (VB) Technique. In this paper, we will report improvement in etch-pit density (EPD) distribution for 2-inch S-doped, 2-inch-Sn-doped and 4-inch S-doped VB InP substrates in comparison to VCZ (SEIs proprietary Vapor pressure controlled Czochralski) InP substrates. EPD of 2-inch S-doped VB InP substrate is lower than SEIs standard EPD specification 500 cm−2 from seed-end to tail-end. Etch-pit densities are drastically reduced compared to those of VCZ with carrier concentration ranging from 3E18 cm−3 to 4E18 cm−3. The VB technique enables a decrease in slip-line defects of S-doped InP with low carrier concentration range. Average lot size of 2-inch S-doped VB InP is almost 1.4 times larger than that of VCZ InP. 4-inch S-doped VB substrates and 2-inch Sn-doped VB substrates are also manufactured using the VB technique.

Growth and characterization of LEC, VCZ and VB InP single crystals

Fe-doped semi-insulating InP single crystals have been grown by LEC, VCZ and VB techniques. Dislocation density, X-ray topograph and residual strain have been measured to characterize crystallographical properties. Macroscopic and microscopic resistivity and photoluminescence intensity have been measured to estimate electrical uniformity. It was found that Fe-doped InP substrates grown by VB technique had superior properties, such as low dislocation density, no lineages and slip-lines, uniform distribution of residual strain, uniform macroscopic and microscopic distributions of resistivity and photoluminescence intensity. It is concluded that VB is the most suitable technique for the growth of high quality Fe-doped InP single crystals.

Quick assessment of homogeneity in large-diameter InP substrate by mapping near-infrared transmittance

A quick imaging technique of near-infrared transmittance has been developed to assess both macroscopic and microscopic homogeneities in VCZ-grown S-doped InP substrates with the large diameters up to 4 inches. In addition to homogeneity assessment of substrates with various diameters, an asymmetric pattern, reflecting the asymmetric shape of solid-liquid interface, as well as a steep striation pattern due to fluctuation of growth speed are observe in a large diameter substrate.