AVS 46th International Symposium
    Manufacturing Science and Technology Group Wednesday Sessions
       Session MS-WeA

Paper MS-WeA8
Assessment of Quadrupole Mass Spectrometry as an In Situ HDP-CVD Process Diagnostic Technique

Wednesday, October 27, 1999, 4:20 pm, Room 611

Session: Metrology II
Presenter: J.A.B. Van Hoeymissen, IMEC, Belgium
Authors: J.A.B. Van Hoeymissen, IMEC, Belgium
C. Hughes, BOC Edwards industrial resident at IMEC, Belgium
M. Heyns, IMEC, Belgium
Correspondent: Click to Email
Process control using in situ techniques is an attractive aid to semiconductor manufacturing. The potential of quadrupole mass spectrometry (QMS) has been assessed as an in situ sensing technique for a silicon oxide high density plasma chemical vapour deposition (HDP-CVD) process. In this paper it is shown that in situ measurements using mass spectrometry can play an important role in the areas of process monitoring, process control and process recipe optimization. The species present in the chamber were analysed via a gas sampling system, with pressure reducing orifice, installed just below the deposition chamber to ensure a representative, real-time, sensitive measurement. Correlation between in situ observations and oxide layer thickness was investigated. H@sub 2@O is an important reaction by-product of the deposition reaction. A direct and highly sensitive correlation between the H@sub 2@O+ signal and oxide layer thickness could be observed. In fact, this QMS signal could be used to monitor oxide layer thickness during deposition. In addition, the [H@sub 2@O+] was found to increase exponentially during deposition. During consecutive depositions of P-doped oxide (PSG) layers, the thickness of the first layer was systematically about 2% higher than the subsequent layers. In situ analysis was carried out monitoring the time resolved intensity of mass 34 (PH@sub 3@+) during the first three PSG depositions. This intensity was clearly higher during the initial phase of the first PSG deposition. The composition of the layers were analysed with SIMS. The results indicate the phosphorus content of the first layer is significantly higher during the initial phase of the deposition. These combined results indicate a higher initial [PH@sub 3@] in the deposition chamber during the deposition of the first PSG layer. These observations prompted an adaptation of the chamber conditioning and clean recipe preceding the first PSG deposition, resulting in the disappearance of the first wafer effect.