Rapid Thermal Processing: When Will it Replace Batch Processing?
- PDF / 794,267 Bytes
- 11 Pages / 414.72 x 648 pts Page_size
- 3 Downloads / 263 Views
M. F. Pas* and S. D. Pas *Semiconductor Process and Device Center and "Manufacturing Science and Technology Center, Texas Instruments Inc., 13536 N. Central Expressway, MS 944 Dallas, Texas 75243 ABSTRACT Rapid Thermal Processing (RTP) is currently well established at the < 0.5 jIm nodes for implant anneal and silicide formation/anneal in logic applications. Rapid Thermal Chemical Vapor Deposition (RTCVD) is being evaluated to deposit thin nitride for the DRAM storage node dielectric. A combination RTP/RTCVD has been evaluated in the form of a cluster tool to evaluate 60 A gate oxides. These applications of RTP are considered to be process enabling because of either improved temperature ramp control or ambient control which are not available in batch processing. However, even with these specialized applications, rapid thermal processing comprises less than 20% of the front end thermal processes in a typical 0.35 jtm fab. Process and equipment issues with rapid thermal processing remain which must be overcome if it is to replace batch processing at the 0.25 jim node. Process issues which are especially critical for RTCVD processing require improved temperature measurement, high growth/deposition rate, and an efficient method of cleaning the process chamber. Equipment issues are reliability and throughput which directly affect the tool cost of ownership. In this paper, each of these issues will be addressed and compared to batch processing using a generic logic process flow. INTRODUCTION The majority of the semiconductor devices processed today in high volume manufacturing have minimum device geometries of > 0.5 rtm. At these geometries the tool of choice for all thermal
processes (T > 4000 C) is a vertical batch furnace. The batch furnace has proven to be reliable and cost effective for the > 0.5 jim device nodes. To increase throughput and improve process control, small batch / fast ramp furnaces are beginning to be used for silicide and implant anneal at the 0.5 jtm and 0.35 jim nodes. These tools have the ability to ramp up at 1000 C/min and ramp down at 600 C/min. Some also offer model based control which improves film uniformity and decreases process time by reducing the amount of time for temperature stabilization[ 1]. However, advanced logic processing at the 0.35 4tm and 0.25 4im device nodes requires more shallow junctions and lower resistance silicides on narrow poly gates[2]. These processes can only be achieved by increasing the temperature ramp up rate to > 250 C/s and improving ambient control, which are features of RTP. 256Mb and 1Gb DRAM require LPCVD nitride deposition with native oxide control which can be achieved using RTCVD nitride[3]. Rapid thermal nitride is being used pre Ta 2O5 deposition. Work is in process on nitrided gate oxides using RTP of N 20 and NO to provide a boron diffusion barrier for pMOS transistors [4,5]. These applications of RTP and RTCVD are currently being moved from R&D to pilot production lines today for manufacturing at 0.35 pim and 0.25 jtm geometries within the next
Data Loading...
