Contamination Monitoring of Semiconductor Processes by VPD HR-ICPMS

Transcription

1 Contamination Monitoring of Semiconductor Processes by VPD HR-ICPMS Jürgen Lerche, SEMICON 2002 AMD, the AMD Arrow Logo and combinations thereof are trademarks of Advanced Micro Devices, Inc. 5/16/2002 1

2 Control of Contamination lower Incoming inspection of chemicals and gases 4% Continuous monitoring of chemical distribution systems and tools 28% Metal Contamination tests on wafer surfaces 40% Higher importance 5/16/2002 2

3 Methods used for Contamination control on Wafers at AMD CV SPV TXRF VPD/HR-ICPMS Mobile Ions in GOX Total Ions, Mobile Ions, Interface State Trace Metals Trace Metals Inline Inline Inline Offline 5/16/2002 3

4 Requirements for contamination monitoring procedure Clean Environment Cleanroom class 1000 /Minienvironments class 1 Determination of a high range of elements High sensitivity for all elements of interest Linearity in a wide concentration range Fast turnaround times to limit tool down time 33 elements DL = 1E+08 to 1E+09 atoms/sqcm from 1E+08 to 1E+12 atoms/sqcm 4 hours turnaround time for VPD Simple and reliable procedure Uptime > 95% 5/16/2002 4

5 HR-ICPMS or QP-ICPMS? QP-ICPMS Easy usage and maintenance Fast measurement => small sample volume Use of GF-AAS necessary for all Ar-interfered elements (Fe, Ca, K) For thick oxide layers some elements are measured too high due to Si/O/F interferences Si containing matrix leads to signal suppression Detection limit not for all elements concerning ITRS roadmap 5/16/2002 5

6 HR-ICPMS or QP-ICPMS? HR-ICPMS High sensitivity Less interference due to high resolution possibility Less signal suppression in high Si matrix (higher plasma power?) Good routine capability More expensive Needs more effort to keep instrument in optimal measurement conditions Long measurement time requires higher sample volume => AMD Decision to use VPD-HR-ICPMS combination 5/16/2002 6

7 AMD VPD-Procedure Native or process SiO2-layer is decomposed (SiO2 + 6HF -> H2SiF6 +2H2O) Etching time dependant on Oxide thickness (e.g. for bare 5 min, 1000A for 15min) 150 µl scan-solution -> dilution to 500µl Double surface scan Scansolution = 1%HF, 1%HNO3, 3% H2O2 5/16/2002 7

8 WSPS2-System 5/16/2002 8

9 ICP-MS Procedure ohr-icpms equipped with Pt-cones, sapphire injector, PFA-chamber, PFA-nebulizer (Mikroflow 100) ASX100 Autosampler 5/16/2002 9

10 ICP-MS Procedure omeasurement parameters: 1300 W Hot Plasma use of low, medium and high resolution sample gas: 1.12 l/min internal standard 1 ppb Y external calibration 50 ppt ppt 5/16/

11 ICP-MS Procedure o Result evaluation and reporting online data transfer to LIMS automated evaluation and reporting 5/16/

12 Detection Limits vs ITRS Roadmap for Metrology Elements Al27(MR) Ca44(MR) Co59(MR) Cr52(MR) Cu63(MR) Fe56(MR) K39(HR) Li7(LR) Na23(LR) Ni60(MR) Zn66(MR) Detection Limits 4.38E E E E E E E E E E E+07 ITRS Roadmap 2007 Surface DL 5/16/

13 Calibration and Linearity 5/16/

14 Spike Recovery Rates Elements Al27(MR) Ca44(MR) Co59(MR) Cr52(MR) Cu63(MR) Fe56(MR) K39(HR) Li7(LR) Na23(LR) Ni60(MR) Zn66(MR) Recovery Rate (%) /16/

15 Processes / Tools monitored by VPD-HR-ICPMS Sinks (APM,SPM...) by blank monitor wafer Gateoxide Furnaces (wafer with gateoxide layer) for layer cleanliness CVD and MD tools for TEOS-Oxide, SiN and SiON for layer cleanliness Implanters for baseline contamination (Ar-implant in thin Oxide) Plasmastripper (bare wafer) Plasma-Etcher (etching back of thick oxide layer) Metrology tools and stocker (bare silicon wafers) Cleanliness of cleanroom environments with monitor wafers (bare wafers) 5/16/

16 Summary VPD / HR-ICPMS fulfills the requirements of ITRS Roadmap beyond 2007 is the most flexible method avaible concerning measurable elements and concentrations although a dedicated laboratory method, it can be used under the right conditions as a production montitoring tool => VPD / HR-ICPMS is an important part of AMD contamination monitoring program 5/16/