Integrated Metrology at the Crossroads
Alex Braun, Senior Editor -- Semiconductor International, 4/1/2000
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The promise of integrated metrology -- whether inside or outside the process chamber, during process or not -- will not be fulfilled as quickly or as smoothly unless both tool providers and end users face the issue of standards, leading to open metrology ports on process tools. This is an important economic issue for end users, since they must be able to split their process tool vendors or lose price leverage. Now, when fabs use multiple vendors each tool has a different on-board solution, complicating metrology so much that it becomes nearly impossible to compare one deposition tool to another because they have different sensor technologies and sensor calibration schemes. Right now, tools not only do not talk to one another; they are not even using the same language. The result is lower tool utilization and less fab productivity.
Process tool user groups must start seriously considering the matter of open metrology standards. If the push toward open standards does not originate with customers, nothing will get accomplished. Everyone likes the idea, for instance, of having multiple deposition tools; but one compatible data stream should be coming from all of them.
De facto standards often work well, but they are double-edged swords for the end user - because although they may be efficient, they tend to be limited to a single vendor, cutting down whatever price leverage the buyer might have had. The only way bargaining ability can be retained is if it is possible to roll in a competitive tool.
Open, flexible standards would enable competition from all corners of the metrology market, while de facto standards could limit metrology providers to the R&D and improvement originated by the tool vendor controlling the standard, who is principally focused on improving his own tool and metrology.
With de facto standards, the investment and improvement cycle for metrology is effectively turned over to the tool vendor, not necessarily to the metrology provider. It is then the vendor, not the user, who determines the kind of sensor to go into the tool, and what kind of measurement is taken and how. We must have the option to select from an array of metrology capabilities ranging from a Wal-Mart to a Saks Fifth Avenue sensor. Different vendors will have different choices (and prices) depending on how complex a sensor the user wants on the tool.
Standards would give the fab the choice to remove the variables induced by the Tower-of-Babel data provided by different vendors. Standards would give end users the ability to put on their tools whatever sensor they deem most appropriate to the need, processes and pocketbook without worrying about complications arising from different methods of taking measurements, or inconsistent numbers.
