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N Type Monitor Wafer for Boron Implant Resistor Process Control

IP.com Disclosure Number: IPCOM000045213D
Original Publication Date: 1983-Feb-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Cavanagh, RA: AUTHOR [+4]

Abstract

For implant resistor process control, it is desirable to isolate any sheet resistance variations due to the implant and anneal process from superfluous variations that are due to any deviations in the concentration of the epitaxy or thickness of the dielectric through which the implant is performed. The monitor wafer presently in use achieves this goal; the process is controlled by the use of an implant into an N type bulk substrate through a well-controlled silicon dioxide layer 225 +/- 25 Angstroms thick. The resulting sheet resistance measurements are indicative of variations due only to the implant and anneal processes.

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N Type Monitor Wafer for Boron Implant Resistor Process Control

For implant resistor process control, it is desirable to isolate any sheet resistance variations due to the implant and anneal process from superfluous variations that are due to any deviations in the concentration of the epitaxy or thickness of the dielectric through which the implant is performed. The monitor wafer presently in use achieves this goal; the process is controlled by the use of an implant into an N type bulk substrate through a well-controlled silicon dioxide layer 225 +/- 25 Angstroms thick. The resulting sheet resistance measurements are indicative of variations due only to the implant and anneal processes.

The topography of product regions receiving the implant resistor is shown in Fig. 1. As may be seen, there are two distinct dielectrics (500 Angstroms of silicon dioxide, 1600 Angstroms of silicon nitride) through which the implant is performed. Each layer has tolerance limits of +/- 10 percent; variations in these thickness nominals, as well as deviations in the epitaxy concentration, can cause variations in the implant sheet resistance nominal, although the implant process itself may be in control. Initial monitor wafers sought to simulate the topography of these implanted regions (see Fig. 2). Resultant sheet resistance nominals and standard deviations measured via a four-point probe were not correlatable to product measurements since the chief source of variation was the diffe...