Process characterization of low-dose, threshold-voltage adjust channel implants using mercury-probe capacitance–voltage measurements

Abstract

Product wafer monitoring of ultrashallow channel implants with an elastic metal gateThe distinct need exists, now, for the capability to accurately and quickly characterize the quality of implants used in threshold-voltage adjusts. In this article we address, in detail, highly sensitive dose and energy monitoring of low-dose implants using a nondestructive, soft-contact mercury-probe capacitance-voltage technique. Currently, wafers are monitored using a wide variety of techniques that work on either a pass-fail basis, or using costly destructive techniques. These techniques lack the sensitivity that is critical for process control of implant and annealing conditions. Data are presented in the form of electrically active carrier density profiles. Detailed information such as partial implant dose, peak carrier density, range, and substrate concentration is determined. These values are enhanced further by the ability to look at uniformity over the entire wafer. From the data collected, rapid and detailed feedback about the condition of the implanter and the annealer͑s͒ is obtained. Quality control and statistical process control of the technique will be analyzed in great detail.

Depth Profiling of Ion-Implanted 4H–SiC Using Confocal Raman Spectroscopy

“…It is worth noting that the implanted regions typically have thicknesses in the sub-micrometer range. To evaluate the electrical properties of the material obtained after ion-implantation and annealing treatment, where the carrier concentration and carrier mobility are of particular interest, and many methods are being used to measure the electrical properties of silicon carbide such as the Hall effect [3], point contact current voltage technique (PCIV) [4], four-point probe [5], and mercury-probe capacitance voltage [6]. Currently, most characterization methods for the electrical properties above-mentioned need the preparation of special measurement structures or will destroy the sample in the process of obtaining the depth distribution of electrical parameters, while the operation procedures are laborious and time consuming: (a) the point contact current voltage (PCIV) [7] has several drawbacks including rather low sensitivity and the lack of required reference samples; (b) the electrochemical etching based depth profiling [8] was investigated but also exhibited insufficient accuracy and reliability.…”