Performance of a Linear Single Wafer IPA Vapour Based Drying System

Abstract:

In this paper, a single wafer linear IPA vapour based vertical drying technique is presented. Using salt residue tests the performance of this technique is evaluated and compared to spin drying. The equivalent film thickness of evaporating liquid is below 0.05µm for blanket wafers, which is two orders of magnitude less than with spin drying. It is also shown that the presence of surface topography (200nm high TEOS features on Si covered with a chemical oxide) does not significantly influence the drying performance. A study of the process window shows that for the setup evaluated in this work best performance is achieved when the IPA/N2 flow rate is above 20 liters per minute and the drying speed is below 8 mm/s. With a manual prototype already very good particle performance is demonstrated.

• Periodical: Solid State Phenomena (Volumes 103-104)
• Pages: 75-78
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.103-104.75
• Online since: April 2005
• Authors: Wim Fyen, Sophia Arnauts, Frank Holsteyns, G. Doumen, Guy Vereecke, Jan Van Steenbergen, Paul W. Mertens
• Keywords: Drying, Evaporation, IPA Vapour, Single Wafer

References

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[6] W. Fyen et al., submitted to: Particles on Surfaces 9, K.L. Mittal ed., VPS Publishing, The Netherlands (2005). U U IPA IPA U U IPA IPA 30 25 20 15 10 5 0 # occurences 0.01 0.1 1 10 δevap (µm) Figure 1: Drawing of the drying unit [2] used in this study: front view (left) and cross section (right). Figure 2: Histogram of all δevap values based on salt residue tests performed on the setup given in figure 1. 0.012 4 6 0.12 4 6 12 4 6 10 δevap (µm) 20 15 10 5 0 N2/IPA flow (slm) 1013 2 4 61014 2 4 61015 2 4 6 K surface conc. (at/cm 2) High values (∼Wet) Low values (∼Dry) (5/18) (4/18) (18/18) (3/18) (1/18) 0.01 0.1 1 10 δevap (µm) 35302520151050 Withdrawal speed (mm/s) 10 13 10 14 10 15 10 16 K surface conc. (at/cm 2) Figure 3: δevap and K surface concentration on O3-last Si wafers, dried on the vertical setup at 7.5mm/s, as a function of the N2/IPA flow rate. Between brackets: number of wet points / total number of measurement points. Figure 4: δevap and K surface concentration on O3-last Si wafers, dried on the vertical setup using an N2/IPA flow rate of 20 slm, as a function of the drying speed. 1012 1013 1014 1015 K surface conc (at/cm2 ) spin dry this setup 0.001 0.01 0.1 1 10 δevap (µm) blanket chemox blanket TEOS patterned chemox/TEOS 100 101 102 103 104 Added LPDs (Obl. Wide) O3-last HF-last this setup (0.06-0.18µm) spin dry (0.1-0.3µm) (spin dry: -84) Figure 5: δevap and K surface concentration on i) blanket wafers (TEOS, O3-last Si) and ii) patterned wafers (200nm TEOS on O3-last Si, measured after dissolving the TEOS in a VPD step). Figure 6: Added LPDs for O3-last and HF-last Si wafers during DI wetting + drying. Settings: a) this setup: 2mm/s using 20 slm N2/IPA; 0.06-0.18µm LSE and b) spin dry at 1800rpm; 0.1-0.3µm LSE. Data for this setup are corrected for edge effects.