Yoshitaka Yokota

Scalability enhancement of FG NAND by FG shape modification

Floating Gate (FG) NAND scaling has been severely challenged by the reduction of gate coupling ratio (CR) and increase in FG interference (FGI) below 30nm node. Firstly, scalability of inverted ‘T’ shaped FG is evaluated by 3D electrostatics simulation. It is shown that coupling ratio (CR) and Floating Gate Interference (FGI) performance can be maintained at the level of 34nm technology down to 13nm node by engineering key aspects of the FG shape namely FG top width (FGW) and effective field height (EFH) in addition to conventional scaling approaches of IPD thinning and spacer к reduction. Secondly, FG shaping is demonstrated down to FGW of 3nm and EFH of 5nm using a sacrificial oxidation technology with no birds beak to demonstrate fabrication feasibility.

Enabling single-wafer low temperature radical oxidation

This paper reports the study of low temperature radical oxidation by using highly concentrated ozone gas in a single-wafer rapid thermal processor. As device structures continue to shrink in geometry, integration of new materials and the complexity of process flows demand growth of high quality oxides with reduced thermal budget. This requirement poses a major challenge for thermal oxidation since lowering the process temperature causes degradation of oxide film quality, in general. Based on the fact that RadOxtrade have already demonstrated unique advantages in a variety of applications for current devices, it is expected that enabling radical oxidation at lower temperature would be beneficial for advanced devices. Highly concentrated ozone gas was employed as the source of radicals. The ozonator used for this study is capable to produce a gas mixture up to 90 vol% ozone (in oxygen) safely by adsorption/desorption technique. Several design of experiments (DOE) were carried out for thickness and thickness non-uniformity study, and film properties were compared with baseline processes using non-contact electrical measurements

Quality and reliability of oxide by low thermal budget rapid thermal oxidation

In order to meet increasing requirement for low thermal budget oxidation in memory and logic applications, RadOx™, previously known as in-situ steam generation (ISSG) oxidation, processes of low thermal budgets were developed. In this paper, oxides obtained by 700°C soak and 900–1050°C spike RadOx™ processes are presented. Sidewall growth behavior in STI-type structures were characterized and showed no bird’s beak encroachment by the developed oxidation processes. Basic bulk oxide (40Å) integrity and reliability characteristics were compared to the 1050°C soak RadOx™ reference. Using planar metal-on-semiconductor (MOS) capacitors as the test vehicles, flat-band voltage (V<inf>fb</inf>), interface trap density (D<inf>it</inf>), leakage current, and stress-induced leakage current (SILC) were measured. V<inf>fb</inf> shift of less than 20mV and D<inf>it</inf> less than 2×10¹¹/cm² were observed from the low temperature soak and spike oxides. Leakage currents from fresh devices and after high current stressing (0.1A/cm²) were comparable to the reference oxide.

High Productivity Single Wafer Radical Oxidation System

This paper introduces a high productivity single wafer radical oxidation system developed for ≤90nm device node. Todays semiconductor device manufacturers face dual challenges of increased technical complexity at virtually every process step, and fast introduction of new products with minimal cost. Up until now, furnaces have satisfied the thermal oxidation requirements in most fabs. The scaling of advanced devices requires higher quality oxides, tighter process control, and smaller thermal budgets at significantly reduced overall processing cost. RadOx™processes have already demonstrated advantages in a variety of applications for current devices, and have been well accepted by many device manufacturers. The availability of RadOx™processes on a reliable, small-footprint platform with reduced pressure capability will enable the technical advantages of single-wafer radical oxidation and the manufacturing requirements for todays economic environment. The Applied Vantage®platform has already gained wide acceptance for implant and silicide anneals, and with the introduction of Applied Vantage®RadOx™, the suite of applications is extended to include reduced pressure processes such as RadOx™. Process and system performance will be presented in this paper with emphasis on the chamber & platform technology elements that enable single-wafer radical oxidation on an industry-proven, cost-effective platform.