Product Quality Assurance

Quality planning

Quality planning is an essential asset of semiconductor projects. It contains all elements increasing the quality of the development as well the items to be added into the manufacturing process. In most cases are these items covered by the Quality management system of the involved companies. In other cases, certain elements needs to be created explicitly and becomes part of the development project.

The most important elements during development:

  • The usage of tools, driving to avoid systematic errors during development. (Example: FMEA)
  • Design verification where the agreed development process is challenged in order to assure a proper development process
  • Setup of a validation plan with characterization and qualification planning.
  • While starting manufacturing a safe launch plan might be used to additional cover uncertainties.
  • The manufacturing process will be reviewed in order to assure the right quality level during manufacturing. The review will result in the following items:

The most important elements for manufacturing

  • Quality assurance of involved suppliers by mean of quality assessments, audits and supplier development.
  • SPC Statisitical proces control on all manufacturing steps.
  • Conformence tests in order to follwo up reliabity related parameters.

Failure Analysis

Failure Analysis is the collection of all required activities to determinate the root cause of a failure. It's a high tech activity requiring a lot of expertise in different domains. A semiconductor has a big divversity of potential root causes and any of the rot cause needs to be investigated on a specifc way.

The background of the faillure analyses is to improve the process and to decrease the failure rate. Many failure mechanisms needs to be covvered by the manufacturing processes and test-steps. Failure analyses mostly leeds to uncovered weaknesses of these processes.

ICR supports

  • To define requirements as input to the product specification in order to be able to analyse the (unwanted) failing product. This proactive input is known as design for failure analyses and requires collaboration between customer, product-manufacturer and supplier.
  • by making the investigation towards the root cause.
  • by advicing the traject to follow.
  • for more complex products, it's important to consider a failure analyses flow. That allows to detect upfront the need for tools or additional requirements towards the product or towards the customer end application

Failure mechanisms 

Failure mechanisms of electronic semiconductor devices fall in the following categories

  1. Material-interaction-induced mechanisms.
  2. Stress-induced mechanisms.
  3. Mechanically induced failure mechanisms.
  4. Environmentally induced failure mechanisms.

Material-interaction-induced mechanisms

  1. Field-effect transistor gate-metal sinking
  2. Ohmic contact degradation
  3. Channel degradation
  4. Surface-state effects
  5. Package molding contamination—impurities in packaging compounds cause electrical failure

Stress-induced failure mechanisms 

  1. Electromigration – electrically induced movement of the materials in the chip
  2. Burnout – localized overstress
  3. Hot Electron Trapping – due to overdrive in power RF circuits
  4. Electrical Stress – Electrostatic discharge, High Electro-Magnetic Fields (HIRF), Latch-up overvoltageovercurrent

Mechanically induced failure mechanisms 

  1. Die fracture – due to mis-match of thermal expansion coefficients
  2. Die-attach voids – manufacturing defect—screenable with Scanning Acoustic Microscopy.
  3. Solder joint failure by creep fatigue or intermetallics cracks.

Environmentally induced failure mechanisms 

  1. Humidity effects – moisture absorption by the package and circuit
  2. Hydrogen effects – Hydrogen induced breakdown of portions of the circuit (Metal)
  3. Other Temperature Effects -- Accellerated Aging, Increased Electro-migration with temperature, Increased Burn-Out