Contamination Control

In line with globally-accepted methodologies and protocols on semiconductor device fabrication, IITBNF strongly advocates and practices contamination-control in its laboratories. Developing anti-contamination policies is a regular and evolving exercise, which is done to achieve two key goals - to control cross-contamination, and to open the equipment for maximum usage by lab members.

This page is a quick reference for designing process flows using IITBNF equipment. Detailed guidelines in the anti-contamination policy document can be found here

Before starting your work, note the contamination category and allowed materials for every tool you need. Category of every tool at IITBNF is specified in the equipment list while allowed materials in each tool are listed here. Both these factors play important roles when designing a process flow or defining an instrument/tool request:

In general, wafers/samples can be processed in equipment within the same contamination group or in groups which can take higher contamination risk as described by the anti-contamination policy flow charts (given below).
If a material is not allowed in the equipment, the designed process flow cannot be allowed even if it follows the anti- contamination policy flow charts (given below).

General Process Flow Guideline Flow charts

Fig 1: Anti-contamination Flow Chart 1
Fig 2: Anti-Contamination Flow Chart 2
Fig 3: Anti Contamination Flow Chart 3
Fig 4: Anti-contamination Flow chart 4

Glass Sample Usage Flow charts

Fig 5: Anti-contamination Flow chart 5
Fig 6: Anti-contamination Flow chart 6


  • There are a few exceptions in which non-standard equipment sequence may be acceptable -- If you have a non- standard process flow requirement, please discuss your project with a member of the Process committee, who should be able to help you design a process flow to accommodate your needs.
  • We will consider experimental data in order to allow a non-standard process flow.
  • Fig. 7 below lists the anti-contamination exception flow chart based on an experimental data submitted to process committee.
    Fig 7: Anti-contamination Exception flow chart 1


  • Inside Samples refer to: Samples Issued at IITBNF; Never taken out from IITBNF lab premises; Never opened or processed or characterized outside of IITBNF labs
  • Outside Samples refer to: Samples which are procured or opened or processed or characterized (even once) outside IITBNF labs

Table 1: Table for some of the Equipment with changed categories.

In Line AIn Line ACIn Line ACTOff Line ALitho
4 Probe Automatic Ellipsometer AFM XPS DSA
Dektak Raith EVO SEM MJB4
Ambios XRD 4 Probe Manual MJB3
All Microscopes All PR Spinners

The above information is just a condensed version of the detailed anti-contamination policy document, which defines and describes the various categories and the allowed process flows. It is strongly recommended that students read the whole document carefully to fully understand the underlying constraints and possibilities. To access the latest version of this document, click here.

Last updated on: 20-Jul-2022