Real-time process and product diagnostics in rapid thermal chemical vapor deposition using in situ mass spectrometric sampling

Abstract

Articles you may be interested inIn situ chemical sensing in Al Ga N ∕ Ga N high electron mobility transistor metalorganic chemical vapor deposition process for real-time prediction of product crystal quality and advanced process control J. Vac. Sci. Technol. B 23, 1386 (2005 10.1116/1.1993616 In situ mass spectrometry in a 10 Torr W chemical vapor deposition process for film thickness metrology and real-time advanced process control Real-time process sensing and metrology in amorphous and selective area silicon plasma enhanced chemical vapor deposition using in situ mass spectrometry Dynamic rate and thickness metrology during poly-Si rapid thermal chemical vapor deposition from SiH4 using real time in situ mass spectrometry Mass spectrometry has been exploited for rapid real-time sensing of both reactant and product species in single-wafer rapid thermal chemical vapor deposition ͑RTCVD͒ of polycrystalline Si from SiH 4 . Active mass spectrometric sampling at pressures to 5 Torr is achieved using two-stage differential pumping of a sampling aperture in the exhaust stream, leading to response times as short as ϳ3 sec to concentration and pressure changes in the reactor during a process carried out in ϳ30 sec. In addition to reactant species, gaseous reaction byproducts have been identified and differentiated from cracking fragments of the reactant through relative intensities of mass fragments as a function of wafer temperature ͑i.e., reaction rate͒. For RTCVD of poly-Si from SiH 4 , carried out in the range 450-800°C at 5 Torr in 10% SiH 4 /Ar, mass spectra reveal not only the time dependence of reactant ͑monitored by SiH 2 ϩ , 30 amu͒, but also-at higher temperatures-reactant depletion and product generation ͑from H 2 ϩ , 2 amu͒. These results demonstrate a basis for using mass spectrometry in real-time process diagnostics and control.

Real-time multivariable control of PECVD silicon nitride film properties

“…In both of these cases, the quadrupole mass spectrometer was used as a sensor for single-loop controllers. Also, workers have used QMS sensing in an RTCVD polysilicon process to monitor reaction byproducts and extract a film thickness [12]. We have demonstrated multivariable control of gas species in PECVD using QMS sensing [13] but until now have not shown control of the most important gas species or the resulting film properties.…”

“…Given positive definite symmetric matrices ( ) and ( ), is given by (12) where is the unique positive definite solution to the matrix algebraic Riccati equation (13) The Kalman filter generates a state estimate that minimizes the variance of the estimation error when and are the covariance matrices for the noise processes and , respectively. Alternatively, these matrices can be used as tuning parameters [20].…”

In Situ Selectivity and Thickness Monitoring During Selective Silicon Epitaxy Using Quadrupole Mass Spectrometry and Wavelets

“…Some recent real-time applications of QMS include: in situ feedback control of a plasma enhanced chemical-vapor deposition (PECVD) process (Knight [3] and Greve et al [4]), sidewall spacer etching (Min [5]), endpoint uniformity sensing and analysis during silicon dioxide plasma etching (Chambers et al, [6], [7]), monitoring of a tungsten metal CVD process (Kobayashi et al [8]), process sensing and metrology in amorphous and selective area silicon plasma deposition (Chowdhury et al [9]), process sensing during rapid thermal chemical-vapor deposition (RTCVD) of polysilicon (Rying et al [10], Tedder [11], [12], Smith [13], Lu [14], [15], and Rubloff et al [16]), and more recently in situ monitoring and characterization of RTCVD thin oxide (SiO ), nitride (Si N ), and tungsten (W) films (Lu et al [17], Rying et al [18], and Gougousi et al [19], [20]). …”

Inverse model-based real-time control for temperature uniformity of RTCVD

“…Polysilicon deposition occurs at temperatures of approximately 800K or higher and the heating of the wafer is accomplished by controlling the power to the three zones of lamp banks. As described in [13], maintaining the pressure constant at 5 torr, the wafer is heated until a preset temperature is reached. The process temperature remains constant for a preprogrammed amount of time, after which the valve to the reactant feed is closed and the lamp power supply is turned off.…”