a spectroscopic film thickness measurement spectroscopic measurement also lends itself well to integration as it only requires a suitably transparent window into the vacuum environment and no substrate contact other thickness measurement techniques are well known or may subsequently be developed the precise nature of which does not affect this invention a suitable metrology instrument is a filmetrics f 20 and at fig3 can be seen a photograph of a filmetrics f 20 integrated with a multichamber single wafer sputtering system where it is mounted to a port attached to the wafer transport module without a separating gate valve and within the wafer transport vacuum system at fig4 is a diagram of the filmetrics f 20 a remote light source and spectrometer are optically connected to the port of the vacuum system by a fibre optic bundle a computer system and software operate the instrument and it is capable of calculating both the film thickness and its refractive index whilst single point measures are useful ideally a multipoint measurement of the substrate would be made and this may be achieved by scanning the substrate under a fixed analysis point e g by passing the substrate on a wafer transport arm under the spectroscopic head the multi measurement can be several measurements at the same point this is simple but improves accuracy by smoothing out errors in the thickness measurement a simple arm extension can thereby effect a radial scan across a substrate such as a wafer by having a line of spectroscopes a series of parallel radial scans may be carried out by a wafer arm extension to effect e g a 49 point analysis.