Real-time, in situ film thickness metrology in a 10 Torr W chemical vapor deposition process using an acoustic sensor

Abstract

Articles you may be interested inReal-time acoustic sensing and control of metalorganic chemical vapor deposition precursor concentrations delivered from solid phase sources In situ mass spectrometry in a 10 Torr W chemical vapor deposition process for film thickness metrology and real-time advanced process control Thickness metrology and end point control in W chemical vapor deposition process from SiH 4 / WF 6 using in situ mass spectrometry Process diagnostics and thickness metrology using in situ mass spectrometry for the chemical vapor deposition of W from H 2 / WF 6 Process gases were sampled from the outlet of a tungsten chemical vapor deposition ͑CVD͒ reactor into an Inficon Composer™ acoustic sensor for in situ chemical gas sensing and real-time film thickness metrology. Processes were carried out on an Ulvac W CVD cluster tool at 10 Torr from 340 to 400°C using a H 2 /WF 6 gas mixture. Sampled gases were compressed through a diaphragm pump up to 100 Torr as required for accurate measurements in the acoustic cell. The high depletion of the heavy WF 6 precursor ͑up to 30%͒ generated a significant variation of the average gas molecular weight and consequently of the mass-dependent resonant frequency measured by the acoustic sensor. The monitored signal was integrated over the process time, and the integrated area was correlated to the deposited W film thickness determined by ex situ measurements. The average error on this in-tool and real-time metrology was less than 1% over 30 wafers processed, either under fixed process conditions or while varying key process variables such as deposition time or temperature. A dynamic physically based simulator was also developed to validate the system response under different process conditions and demonstrate the fundamental understanding of this method. The metrology achieved represents a significant improvement over previously published data ͓L. Henn-Lecordier et al., J. Vac. Sci. Technol. A 19, 621 ͑2001͔͒ obtained on the same system but in the sub-Torr process pressure regime, where low depletion rates ͑around 3%͒ had limited the metrology to 7% error. With an error less than 1%, this in situ chemical sensing approach could be efficiently exploited for real-time course correction, e.g., using end-point film thickness control.

In situ chemical sensing in AlGaN∕GaN high electron mobility transistor metalorganic chemical vapor deposition process for real-time prediction of product crystal quality and advanced process control

“…[4][5][6] Our research group at the University of Maryland has been an active contributor in these various aspects of APC, especially in the use of in situ chemical sensors to drive real-time wafer-state metrology and control in Si ULSI processes. [36][37][38][39][40][41][42][43][44][45][46] Understanding the relevant challenges currently facing the development of GaN-based processes for manufacturing in electronic applications, we have applied similar APC approaches in hopes of achieving manufacturing reproducibility and increased understanding of the process chemistry. [47][48][49][50][51][52] We have employed in situ mass spectrometry for real-time process sensing during the GaN MOCVD process, initially devoted to numerous FDC applications and subsequently to quantitative metrologies for predicting material quality, film thickness, etc.…”

In-Situ Metrology: the Path to Real-Time Advanced Process Control

“…7. [40,41] In this case, 10 wafers processed at 490°C showed a wafer-to-wafer drift, as evident in the Fig. 7.…”

“…In fact, real-time in-situ metrology for deposition thickness has been demonstrated at a comparable level of accuracy using acoustic sensors. [40,41] -17000 .…”

Real-time material quality prediction, fault detection, and contamination control in AlGaN∕GaN high electron mobility transistor metalorganic chemical vapor deposition process using in situ chemical sensing

“…This would also allow real-time closed-loop control to maintain desired level of concentration in the face of run-to-run drift in concentration due to changes in the liquid source vapor pressure with overtime usage. 22 Here, the mass spectrometer sensor monitoring the growth reaction far downstream of the wafer provided an additional capability to detect such faults in real time. Thus, although the former option may be a more elegant solution, the latter option is extremely attractive because it allows for multiple applications with both processand wafer-state control, and other types of real-time fault detection applications at the same time with a single sensor.…”

“…4,5 Our research group has been an active contributor in various aspects of APC, especially in the use of real-time in situ chemical sensors for both FDC and course correction. [6][7][8][9][10][11][12][13][14][15][16] In view of the relevant challenges currently facing the development of GaN-based processes for manufacturing in electronic applications, we have applied similar APC approaches based on our past experience in Si-based processes in hopes of achieving process reproducibility sufficient for manufacturing. 17,18 We have employed in situ mass spectrometry in AlGaN / GaN / AlN metalorganic chemical vapor deposition ͑MOCVD͒ processes to grow high electron mobility transistor ͑HEMT͒ heterostructures on semi-insulating SiC for high frequency/power electronic devices.…”