SEMI MF1618 - Practice for Determination of Uniformity of Thin Films on Silicon Wafers -

Abstract

NOTICE: This Document was reapproved with minor editorial changes.

 

The purpose of this Practice is to promote commonality of approach to the analysis of uniformity among all parties needing to generate or assess such information, including manufacturers of the basic test instrumentation to be used.

 

This Practice is intended for process control, research and development, and process equipment evaluation purposes. It is intended for the benefit of semiconductor device and equipment manufacturers alike so that acquisition, reduction, and communication of thin film data is consistent among various parties who may need to concur on interpretation of the results of a thin film fabrication-process step.

This Practice covers a set of site distribution patterns for measuring the uniformity of a property of a thin film on a silicon wafer, as well as simple procedures for analyzing and reporting the results of those measurements.

 

This Practice is intended for use as a template for the evaluation of the uniformity of intrinsic film properties such as thickness or composition, and also film functional characteristics such as sheet resistance and reflectivity. The resulting information may be used to assess the uniformity of the film itself or of the layer formation process. This Practice is not directly applicable to evaluating wafer-to-wafer or lot-to-lot variations.

 

This Practice is intended for use with any thin film or layer type, or formation technique, for which basic measurement instrumentation and capability exists that, is appropriate to the film parameter of interest. This Practice is intended for layer growth and deposition techniques such as epitaxy, implantation, thermal and chemical vapor deposition (CVD) oxidation, and metallization, as well as for layer modification such as various means of layer etching.

 

This Practice is intended for use with all silicon wafer sizes and types when measuring uniformity of film properties and characteristics. This Practice describes measurement site patterns and determination of their spatial coordinates on the wafer, as well as the statistics to be used when reducing the measurement data to determine uniformity. For each of the sampling plans, the exact number of measurement sites is chosen based on the size of the wafer being used, the desired spatial resolution of the measurement instrument, and whether maximal, or somewhat lesser information density is desired. However, in all such choices, the pattern of measurement sites, the rules for selecting their coordinates on the wafer, and the statistical calculations of the results should remain consistent with the procedures of this Practice.

 

This Practice can be used with any measurement method, procedure or instrumentation that can measure the needed film property or characteristic with sufficient precision and spatial resolution to reveal the needed information on spatial nonuniformity of the film. This Practice does not itself contain details on performing any specific measurement.

 

Not all types of measurements that may need to be used for evaluation of the uniformity of a thin film have formal procedural standards. SEMI MF374, SEMI MF576, SEMI MF1392, SEMI MF1393, and SEMI MF1529 give details of measurement procedures that may be applied to evaluating the uniformity of thin film properties.

 

This Practice does not deal with acquisition or analysis of uniformity data where it is desired to take more than one measurement per specified spatial cell such as is commonly done for wafer site flatness measurements.

 

This Practice makes no recommendations regarding the interpretation of the statistics that result from analysis of the data acquired with regard to the goodness or badness of given values of the test statistic, nor does it make recommendations regarding decisions about the process cycle or equipment used to produce the thin film that was measured.

 

The principles of this Practice may be adapted to determine the uniformity of bulk silicon wafer properties such as interstitial oxygen content and resistivity, but depending on the desired property and the chosen measurement technique, depth-dependent variations may be misinterpreted as lateral variations.

 

Referenced SEMI Standards (purchase separately)

SEMI M1 — Specification for Polished Single Crystal Silicon Wafers

SEMI M20 — Practice for Establishing a Wafer Coordinate System

SEMI M59 — Terminology for Silicon Technology

SEMI MF81 — Test Method for Measuring Radial Resistivity Variation on Silicon Wafers

SEMI MF374 — Test Method for Sheet Resistance of Silicon Epitaxial, Diffused, Polysilicon, and Ion-Implanted Layers Using an In-Line Four-Point Probe with the Single-Configuration Procedure

SEMI MF576 — Test Method for Measurement of Insulator Thickness and Refractive Index on Silicon Substrates by Ellipsometry

SEMI MF1392 — Test Method for Determining Net Carrier Density Profiles in Silicon Wafers by Capacitance-Voltage Measurements with a Mercury Probe

SEMI MF1393 (Withdrawn 0705) — Test Method for Determining Net Carrier Density in Silicon Wafers by Miller Feedback Profiler Measurements with a Mercury Probe

SEMI MF1529 — Test Method for Sheet Resistance Uniformity Evaluation by In-line Four-Point Probe with the Dual-Configuration Procedure

 

Revision History

SEMI MF1618-1110 (Reapproved 0322)

SEMI MF1618-1110 (Reapproved 1115)

SEMI MF1618-1110 (technical revision)

SEMI MF1618-1104 (technical revision)

SEMI MF1618-02 (first SEMI publication)

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