Thickness metrology and end point control in W chemical vapor deposition process from SiH4/WF6 using in situ mass spectrometry

Abstract

In-situ sensing using mass spectrometry and its use for run-to-run control on a W-CVD cluster tool AIP Conf.Process diagnostics and thickness metrology using in situ mass spectrometry for the chemical vapor deposition of W from H 2 / WF 6 Real-time, in situ chemical sensing has been applied to achieve reaction metrology and advanced process control in a low pressure tungsten chemical vapor deposition process based on WF 6 and SiH 4 reactants ͑silane reduction process͒. Using mass spectrometry as the sensor to detect both product generation (H 2 ) and reactant depletion (SiH 4 ) at wafer temperature of 200-250°C, these signals provided a direct real-time measurement of deposited film thickness with an uncertainty less than 2%, and this thickness metrology signal was employed to achieve real-time process end point control. When reactant conversion rates are sufficient ͑ϳ20% in this case͒ as often occurs in manufacturing processes, the thickness metrology ͑1.0%-1.5%͒ and control ͑ϳ1.5%-2.0%͒ accuracies are in the regime needed for meaningful application of advanced process control. Since the in situ sensor delivers a metrology signal in real time, real-time process control is achieved, enabling compensation for random process disturbances during an individual process cycle as well as for systematic wafer-to-wafer process drifts. These results are promising for manufacturing from the standpoints of metrology accuracy and application in real-time 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.…”

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

“…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.…”

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

“…For a low pressure (0,1 torr) process, a thickness metrology of 1-1.5% accuracy was obtained using the H 2 product generation signal. [37] By tracking the integrated product signal and terminating the process when the target value was reached, run-to-run variability was reduced from ~4% to -1.5%. Figure 3a shows the improvement for the mass spec product signal upon imposing real-time end point control, while Fig, 3b shows the corresponding improvement in control of the deposited W film thickness, as determined post-process FIGURE 2.…”

“…For example, RTCVD poly Si and oxide results showed generation of reaction products and depletion of reactants to an extent dependent on reaction rate, and they indicated the possibility of using these for deposition rate metrology [34] . More recently, we have evaluated the metrology accuracy obtainable using downstream mass spec for several W CVD processes, both H 2 reduction [35,36] and SiH 4 reduction [37], as carried out in a Ulvac ERA-1000 W CVD cluster tool. With reasonable reactant conversion rates (-20%) in the SiH4 reduction process, thickness metrology of 1-1.5% accuracy was demonstrated and exploited to achieve real-time end point control consistent with this metrology.…”

“…With reasonable reactant conversion rates (-20%) in the SiH4 reduction process, thickness metrology of 1-1.5% accuracy was demonstrated and exploited to achieve real-time end point control consistent with this metrology. [37] The experimental setup is indicated in Fig. 1, showing differentially pumped mass spectrometry (Inficon Transpector™) arranged to sample reactant and product species in the CVD reactor.…”