Autonomous on-wafer sensors for process modeling, diagnosis, and control

Abstract

This paper explores the feasibility of constructing an autonomous sensor array on a standard silicon wafer. Such a sensor-wafer would include integrated electronics, power, and communications, and would be capable of being placed into a standard production process step, or short sequence of steps. During the processing of the sensor-wafer, various process parameters would be measured and recorded. There are several uses for such a sensor wafer, including equipment characterization and design, process calibration, and equipment qualification and diagnosis. In this paper, various sensor architectures, power supplies, communications methods, and isolation techniques are discussed, and particular choices are made. Several proof-of-concept designs that measure film-thickness and temperature are discussed, and test results are reviewed for each design.

Integrated Bake/Chill Module With In Situ Temperature Measurement for Photoresist Processing

“…However, these methods run into difficultly when implemented in an environment where the "hotplates" are encapsulated with a lid on them. A wireless version of such instrumented wafer does exist [3]; however, both approaches are typically used at the initial characterization phase for determining the optimum recipes since the actual substrates do not have embedded sensors. During the subsequent runs, the process is subjected to process drifts and disturbances (e.g., wafers of different warpages); with in situ temperature measurement, we can correct for these changes in the process easily.…”

Integrated metrology and processes for semiconductor manufacturing

“…However, these methods run into difficultly when implemented in an environment where the "hotplate" are encapsulated with a lid on them. A wireless version of such instrumented wafer do exist [8], however both approaches are typically used at the initial characterization phase for determining the optimum recipes since the actual wafers do not have embedded sensors. During the subsequent runs, the process is subjected to process drifts and disturbances (e.g.…”

An Integrated Aerial Image Sensor for Lithography Diagnostics

“…Assuming that the maximum intensity and minimum intensity are independent, we have: var(CDC) =ma (2 aCDIC )2 + Uo (aCDIC )2 Var(CD'Co = T,nx( ,max ",in ,imin (5) The noise of Io,max an I0Min is assumed to be mainly composed of photon noise, which refers to the inherent variation of the incident photon flux. Assuming that the photo density follows a Poisson distribution, the photon noise has a square root relationship with the transmitted photon flux corresponding to Iomax and 10mMin.…”

“…However, most of the "direct" methods involve the integration of the aerial image sensor to the exposure tool or depend on additional stand-alone inspection instruments. Integrating the sensor into the projection tool, in particular, presents various disadvantages in terms of cost and overall reliability of the integrated system, since malfunctions in the in-situ metrology functionality will affect the stability of the process, and may reduce its throughput [5]. A portable sensor being used as a reference across multiple tools has the added advantage of eliminating sensor-to-sensor repeatability as one potential source of error.…”