Paper PS-ThP26
Capability of Microwave Plasma Source for 450 mm Etching Apparatus

Thursday, November 3, 2011, 6:00 pm, Room East Exhibit Hall

To produce semiconductors at low cost, the transition to 450 mm-sized wafers is being considered. For semiconductor fabrication on 450 mm substrates, the etching performance is expected to equal or exceed 300 mm substrate capability with improved productivity requirements. A 450 mm substrate capable apparatus was developed on a proven plasma source using microwave electron cyclotron resonance (ECR) currently utilized for 300 mm equipment. We have evaluated plasma uniformity by using: 1) Single Langmuir probe with -50 V bias to measure ion current flux (ICF) distribution in the plasma reactor. The plasma generated area and the spatial distribution of ICF were scanned in the radial and z-axis directions in the reactor. 2) A 41-point wafer stage to measure ICF distribution. 3) Etch rate uniformity of poly-Si and SiO2 using coupon samples attached on 450 mm bare Si wafers. We used HBr/Cl2/O2/Ar gas and 0.1-10 Pa pressure range as test conditions.

We found that the high density plasma generated at the ECR zone and the shape of the plasma was ring-shaped. This ring-shaped plasma diffused and became increasingly uniform, finally becoming almost flat at a height of 25 mm above the wafer stage. To evaluate ICF distribution of the wafer stage, 41 pads were used to measure plasma density distribution using about 500 test conditions. By controlling the magnetic fields, non-uniformity of ICF below ±5% was achieved for several test conditions of gas and pressure. Poly-Si and SiO2 etching rate were observed to be very similar to rates seen using 300 mm substrate equipment with non-uniformity below ±1% within a wafer.