MOSFET 1962 Step 17 Sodium Contamination Industry Response

# The Sodium Problem Becomes an Industry Problem: How Fabs Responded, Not Just How It Was Discovered

## 1. From a Discovered Defect to a Standard Practice

This series' Step 7 already described mobile-ion contamination shifting threshold voltage after a device was finished; what it did not cover is what the industry actually did about it once the mechanism was understood. Sodium ions, migrating through the gate oxide under bias and temperature stress, were traced to ordinary sources already present in most fabs -- human skin contact, some chemical reagents, even certain furnace materials -- which meant the fix was not a redesign of the device but a wholesale change in fab handling discipline: deionized rinses, gloved handling, and bias-temperature stress testing added as a standard screening step before a device ever shipped.

From Discovered Mechanism to Standard Practice Step 7 named the defect; this is the industry-wide fix MECHANISM, STEP 7 sodium ions migrate in oxide under bias and temperature threshold drifts after ship SOURCE TRACING skin contact, reagents furnace materials ordinary fab handling INDUSTRY RESPONSE deionized rinse protocols gloved wafer handling bts screening before ship Step 7 is not retold here -- this step covers only the industry-wide response that followed it.

## 2. A Practice That Outlived the 1962 Device

Bias-temperature-stress screening and fab-cleanliness discipline, adopted industry-wide in response to this specific problem, remained standard practice for essentially every MOS process that followed, including the silicon-gate process this project's siliconGate_1967 series covers -- named here only, since that series does not need to re-derive why the cleanliness discipline exists, only to assume it.

A Fix That Became Permanent Practice adopted once, never abandoned by later mos processes 90 1962-63 fabs 40 mid-1960s fabs 10 1967 silicon-gate fabs Contamination-driven threshold drift dropped sharply once cleanliness discipline became standard. Later processes, including siliconGate_1967, inherit the practice rather than re-earning it.

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