Determination of surface roughness by contact profilometry for gas

SEMASPEC Test Method for Determination of Surface Roughness by Contact Profilometry for Gas Distribution System Components

SEMATECH
Technology Transfer 90120400B-STD

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SEMASPEC Test Method for Determination of Surface Roughness by Contact Profilometry for Gas Distribution SystemComponents
Technology Transfer # 90120400B-STD SEMATECH

February 22, 1993
Abstract: This SEMASPEC describes the determination of numerical values for surface roughness of components used in ultra-high purity gas distribution systems. Application of this test method is expected to yield comparable data among components tested for the purposes of qualification for installation. This document is indevelopment as an industry standard by Semiconductor Equipment and Materials International (SEMI). When available, adherence to the SEMI standard is recommended.

Keywords:

Surface Roughness, Facilities, Gas Distribution Systems, Specifications, Components, Component Testing

Authors:

Jeff Riddle

Approvals:

Jeff Riddle, Project Manager Venu Menon, Program Manager Jackie Marsh,Director of Standards Program Gene Feit, Director, Contamination Free Manufacturing John Pankratz, Director Jeanne Cranford, Technical Information Transfer Team Leader

1 SEMASPEC #90120400B-STD SEMASPEC Test Method for Determination of Surface Roughness by Contact Profilometry for Gas Distribution System Components 1. Introduction Semiconductor cleanrooms are serviced by high-purity gasdistribution systems. This document presents a test method that may be applied for the evaluation of one or more components considered for use in such systems. 1.1 1.1.1 Purpose The purpose of this document is to define a method for testing components being considered for installation into a high-purity gas distribution system. Application of this test method is expected to yield comparable data amongcomponents tested for purposes of qualification for this installation. This method describes the determination of numerical values for surface roughness. Scope Surface feature sizes from 0.25 µm (10 µin.) Ra to 3.0 µm (120 µin.) Ra are measured using this method. A statistical analysis of a profilometer graphic output that describes a fractal dimension measurement is included in the Appendix. Theresulting numerical value is referred to as the fractal-based roughness, RF. Limitations Surfaces having roughness indices greater than 0.25 µm (10 µin.) Ra may be reliably measured with a typical surface contact type instrument, provided that the instrument chosen is capable of resolving features on the order of 0.10 µm (4.0 µin.). Surfaces having roughness indices equal to or less than 0.25 µm (10µin.) Ra should be measured with a non-contact surface analyzer. For most stylus-based profilometers, 0.25–µm (10–µin.) Ra represents the lower detection limit (LDL) with reasonable accuracy. (Figure 1 graphically highlights the difficulty of measurement). Refer to X1.1 for possible contact measurement of surfaces under 0.25 µm. The direction (or lay) of regular surface features (e.g., grooves),relative to the stylus stroke direction, can substantially affect the reported roughness index. To avoid discrepancies arising from such situations (such as in cases where a pronounced lay exists), the sample lay must be oriented at a 90 degree angle to the direction of stylus movement. In many cases, this will require mechanical rotation of the sample to obtain such a directional orientation. If thisis not possible, as could be the case for very small passageways etc., the exception must be noted along with the reported data.

1.1.2 1.2 1.2.1 1.2.2

1.3 1.3.1

1.3.2

1.3.3

Technology Transfer # 90120400B-STD

SEMATECH

2 2. 2.1 Reference Documents ANSI1 ANSI B.46.1-85 Surface Texture (Surface Roughness, Waviness, and Lay), ANSI/ASME 1985

ANSI Y14.36-1987 Surface Texture...