Charavel, Rémy
[UCL]
Olbrechts, Benoit
[UCL]
Raskin, Jean-Pierre
[UCL]
The effects of various deposition and annealing conditions of Plasma Enhanced Chemical Vapour Deposited (PECVD) oxide films on residual stress, optical index, BHF etch rate, surface roughness for thick PECVD oxide films are investigated. Rapid Thermal Annealing (RTA) and annealing in regular furnaces are both considered and compared. AFM measurements were required to measure the oxide surface roughness. Thick PECVD oxide films of 1.5 mu m were deposited on 380 mu m bulk silicon wafer. Starting from a conventional recipe the power, the [N/sub 2/O/SiH/sub 4/] ratio and the total gas flow were successively varied. An increase of the total gas flow or/and a decrease of power lead to an increase of the BHF etch rate and surface roughness but on the other hand decrease the residual stress. A high ratio N/sub 2 /O/SiH/sub 4/ yields to oxide with low BHF etch rate but characterized by higher residual stress. RTA reduces the stress and the BHF etch rate drastically and it is more efficient than conventional annealing in standard furnace. Actually, RTA reduces stress in a very short period of time (few seconds) compared to standard annealing, and then it does not contribute to doping diffusion of the already implanted regions of the wafer. From a compressive stress of about 80 MPa, RTA of 15 s leads to a residual stress of only 30 MPa and bring the BHF etch rate to acceptable values in the range of 2000 A /min for high N /sub 2/O/SiH/sub 4/ ratio oxide. One main application of this RTA stress release of oxide is to provide processed wafers with a bow compatible(less than 10 mu m) with Chemical Mechanical Polishing (CMP) or wafer bonding.
Bibliographic reference |
Charavel, Rémy ; Olbrechts, Benoit ; Raskin, Jean-Pierre. Stress release of PECVD oxide by RTA.Smart Sensors, Actuators, and MEMS (Maspalomas, Gran Canaria, Spain, 19-21 May 2003). In: SPIE - the International Society for Optical Engineering. Proceedings, Spie-int. soc. opt. eng2003, p.Vol. 5116, p. 596-606 |
Permanent URL |
http://hdl.handle.net/2078.1/68064 |