An investigation was undertaken to evaluate the potential of using mutual inductance (eddy current) measurements to determine doping levels in polycrystalline silicon (polysilicon). The main advantage of eddy current measurements is that they are non-contact and the oxide which grows on the polysilicon is transparent to the magnetic fields used to generate the eddy currents. This allows the doped polysilicon sample to be measured immediately following the doping process and eliminates the need to etch the oxide which must be removed for the traditional four-point probe measurement. The elimination of the HF acid etch step not only saves on materials costs, it removes a potentially hazardous step from the process and does away with the need to dispose of a hazardous waste. This paper correlates the eddy current measurements with traditional four-point probe measurements, and investigates the influences of the substrate and backside polysilicon film sheet resistances on the frontside measurement.
Typically metal film processes have been controlled by using monitor wafers. A representative film is deposited on the monitor wafer (witness sample) then the sheet resistance uniformity is measured with a four- point probe. It is assumed that the films on subsequently processed product wafers will have the same characteristics as the film on the monitor. Monitor wafer costs are becoming prohibitive as the industry transitions to 200 millimeter wafers and beyond. Also monitor wafer preparation takes valuable time which could be used for production. Finally monitor wafers also take up valuable space in processing equipment, which could be occupied by product wafers, reducing the overall fab capacity. A mutual inductance technique is described which can be used to measure the sheet resistance of blanket metal films directly on product wafers. This not only reduces the need for sheet resistance monitor wafers and adds system capacity but also gives valuable insight into film properties on the actual product wafer. Data will be presented showing the incorporation of this technique into a 150 millimeter production facility.
This paper presents innovative software developed to help generate a temperature calibration curve and to mathematically manipulate and combine multi-point wafer maps. The software automatically applies the calibration curve to a map of film parameters to provide a quantitative map of temperature uniformity. Several process examples are presented to demonstrate the flexibility and convenience of the software. 1.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.