Single-wafer integrated semiconductor device processing

Visions of future wafer fabs include the use of integrated single-wafer processors to achieve fast cycle times and contain rising production costs. A survey of IC manufacturers, equipment vendors, and IC manufacturing literature was used to generate hypothetical conventional and alternative fabs to evaluate the effect of integrated single-wafer processing on cycle time and cost performance. The distinguishing features of the alternative fab are 1) all thermal processes performed on singlewafer processors; 2) back-end wet cleans performed on singlewafer processors; 3) integration of single-wafer processors into clusters or cells wherever practical, and 4) extensive use of insitu insitu insitu process monitors to replace in-line process monitors. Modeling and simulation of the resulting fabs suggest that integrated singlewafer processing can reduce the cycle time of conventional fabs by about 50% without having a significant effect on wafer production cost. Tool integration and single-wafer processing must be used together to achieve these performance improvements. Although traditional lot sizes appeared to be appropriate for both fabs, improvements in cluster tool reliability and process step similarity could change optimal integrated tool configurations and reduce optimal lot sizes in the future.

Section: B Thermal Processesmentioning

confidence: 99%

Section: B Thermal Processesmentioning

confidence: 99%

Cost and cycle time performance of fabs based on integrated single-wafer processing

Wood

1997

“…When there are parallel chambers at process step , the successive wafers visit the chambers in a cyclic order during a robot work cycle. For instance, the chamber visit sequence for wafer flow pattern (2,3) is , where is the -th parallel chamber at process step . Such cyclic use of parallel chambers is intended for fair use of the chambers.…”

Section: A Cluster Tool Operation Modelmentioning

confidence: 99%

“…Otherwise, the wafer is subject to quality problems due to residual gases or heat. For example, low pressure chemical vapor deposition (LPCVD) is processed under medium vacuum of 0.25-20 torr, and higher temperature of 550 C-800 C in order to form nonvolatile solid films like nitride, oxide, Epi-Si and poly-Si [2], [3]. When the wafer delay at each process step of LPCVD exceeds 20 s, the wafer surface deteriorates because of excessive exposure to residual gases under high temperature and the wafer is scrapped.…”

Section: Introductionmentioning

confidence: 99%

Scheduling analysis of time-constrained dual-armed cluster tools

Kim

Lee

et al. 2003

246

Abstract-Cluster tools, each of which consists of several singlewafer processing chambers and a wafer handling robot, have been increasingly used for diverse wafer fabrication processes. Processes such as some low pressure chemical vapor deposition processes require strict timing control. Unless a wafer processed at a chamber for such a process leaves the chamber within a specified time limit, the wafer is subject to quality problems due to residual gases and heat. We address the scheduling problem for such time-constrained dual-armed cluster tools that have diverse wafer flow patterns. We propose a systematic method of determining the schedulable process time range for which there exists a feasible schedule that satisfies the time constraints. We explain how to select the desirable process times within the schedulable process time range. We present a method of determining the tool operation schedule. For more flexible scheduling under the time constraints, we propose a modification of the conventional swap operation in order to allow wafer delay on a robot arm during a swap operation. We compare the performance of the new swap strategy with that of the conventional swap strategy.

“…Activity-oriented approach considers cluster tools as (discrete) concurrent systems, in which several activities can be performed simultaneously, for example, different wafers can be processed by different modules at the same time, and also the robotic transporter can be moving to a position required by a future step [26]. Activity-based approach does not focus on any specific sequence of events; it takes into account the whole spectrum of possible behaviors of the analyzed system, so it is more general than the critical-path approach.…”

Section: Introductionmentioning

confidence: 99%

Cluster Tools With Chamber Revisiting—Modeling and Analysis Using Timed Petri Nets

Zuberek

2004

Abstract-Timed Petri nets are formal models of discrete concurrent systems. Since the durations of all activities are included in the model descriptions, many performance characteristics can be derived from such models. In the case of cluster tools, net models represent the flow of wafers through the chambers of the tool as well as consecutive actions performed by the robotic transporter. Steady-state performance of cluster tools with chamber revisiting is investigated in this paper. A systematic development of detailed tool schedules, based on a general behavioral description of the tool, is proposed and is used to derive the corresponding Petri net models. Symbolic performance characteristics of the modeled tools are obtained by using place invariants, without exhaustive reachability analysis. Simple examples presented in the paper can be easily extended in many ways.