moisture measurement
UK), and Physikalisch-Technische Bundesanstalt (PTB, Germany). The multi-year, multinational study determined that the deviation of Tiger’s LaserTrace analyzer was less than two percent (2%) over the three (3) year period in the entire range of 10 ppb – 2 ppm.
LaserTrace 3
While the semiconductor industry has long relied on the LaserTrace system for absolute measurements, shrinking geometries on the wafer have resulted in even tighter controls being placed on the purity of gases used in the semiconductor manufacturing process. As some fabs set alarm limits for moisture as low as 500 ppt, the semiconductor industry is now requiring even lower LDLs. Once again, Tiger Optics has responded to the industry’s needs.
At Semicon West 2011, Tiger Optics introduced the LaserTrace 3, for which the LDLs of most contaminants and gas matrices have been cut in half. For moisture in helium, the LDL is now an astonishingly low 100 ppt (Figure 3). The achievement is one of the reasons that the Tiger Optics’ LaserTrace 3 won the prestigious Golden Gas Award for 2012 from Gases and Instrumentation International Magazine in the Gas Analysis and Detection category.
In addition to the dramatic reduction in the LDL, the engineering team at Tiger Optics has increased the speed of response for a multi-channel LaserTrace 3 by a factor of more than 2.5x. The end user can be assured that the LaserTrace 3 will display updated moisture concentrations on each channel every two seconds. This dramatic improvement in the LDL and the speed of response is the result of a tremendous amount of work on both the hardware and the software of the system. In keeping with Tiger’s philosophy of focusing on the needs of the customer, existing LaserTrace users are able to upgrade the hardware and the software of their systems to achieve the performance of the LaserTrace 3.
LaserTrace 3x While the LaserTrace 3 (coupled with the associated moisture and/or oxygen, etc. measurement cells) is focused on measuring the contamination levels of the bulk gases as they enter the fab, the LaserTrace 3 platform is also utilized to monitor the moisture levels in the exhaust gases of low temperature epitaxial process tools from manufacturers such as Applied Materials, Inc., and ASM International N.V.
In order to perform the required moisture measurements at pressure levels down to 50 torr (or below), Tiger uses a reduced-pressure or Epi sensor. Initially, the industry needed only two Epi sensors to be coupled to a single LaserTrace 3 electronics module so that the exhausts from a two- chamber epi system could be monitored independently. Subsequent requests to also monitor the moisture levels within the transfer chamber required a redesign of the electronics module.
According, Tiger Optics developed its LaserTrace 3x, to permit monitoring the transfer chamber at reduced pressures while also monitoring each of the tool’s epi exhausts. Tool owners can monitor for moisture in these critical areas after preventive maintenance is performed on the tool. The result is that the tool can now be brought back on-line when the moisture levels are low enough to insure that the product will not be impacted due to moisture contamination. The savings from the reduced downtime of the tool, along with a reduction in the number of wafers that might need to be scrapped due to moisture contamination, is sure to bring about a high return on investment (ROI).
Working in Tandem The semiconductor industry, having set the goal to produce 14nm nodes and 450mm wafers by 2015, can only intensify its strenuous efforts to control the quality of the inputs and the
manufacturing process itself. With the LaserTrace 3 insuring the quality of the input gases and the LaserTrace 3x insuring the quality of the process, the hard-working fabs may continue to score—
by orders of magnitude—improvements upon previous generations of product.
© 2012 Angel Business Communications. Permission required.
References
i.Grove,Andrew (2000,June).Harvard International Conference on Internet and Society 2000.Speech presented at Harvard University,Cambridge,MA. ii. Brewer,P
.J.,Milton,M.J.T.,Harris,P .M., Bell,S.A.,Stevens,M.,Scace,G.,Abe,H.,and Mackrodt,P .,2011,EURAMET 1002:International Comparability in Measurements of Trace Water Vapour.Middlesex,UK: National Physical Laboratory Issue 2 2012
www.siliconsemiconductor.net 35 Fig 3 I’m a great believer in particularly being
alert to changes that change something, anything,by an order of magnitude
Andrew Grove, former CEO, Intel Corporation
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