MOSFET 1962 Step 20 Close Extension Single Channel MOSFET Legacy

# Close This Extension: a Commercially Difficult Device That Still Changed What Was Possible

## 1. An Honest Final Accounting

This extension has told a more complicated story than Step 10's original "second transistor family enters production" close: the device that entered production in 1962-63 was commercially difficult -- lower yield than bipolar, one reliable polarity only, and a contamination sensitivity the industry had to learn to manage from scratch -- and it won its first markets on specific electrical properties, not on cost. That is the honest state in which this device's own decade closes, and this extension does not claim the difficulties were somehow solved within 1962-63's own technology; they were not.

What This Device Actually Achieved by Its Own Decade's End real, bounded progress -- not a solved story PHYSICS PROVEN atalla, kahng, bell labs steps 1, 11 of this series COMMERCIALIZED, DIFFICULTLY hofstein, heiman, rca lower yield, pmos only MARKETS WON SELECTIVELY impedance, power niches not general-purpose yet Progress was real and specific. The device was not yet the general-purpose part it would become.

## 2. Naming What Comes Next, Without Retelling It

Two genuinely related threads continue this device's story elsewhere in this project: the process-control work Fairchild was already doing in 1962 (named in Step 19) matures into the self-aligned polysilicon-gate process this project's siliconGate_1967 series documents, and the fixed-oxide-charge, PMOS-only constraint named in Step 14 is the specific limitation later NMOS and complementary (CMOS) processes -- covered elsewhere in this project -- eventually overcome. Neither thread is retold here; both are named honestly as open continuations, which is the only closing claim this extension makes.

Two Real Continuations, Named Not Retold where this device's unresolved constraints get addressed, elsewhere in this project 90 Process control -> siliconGate_1967 75 PMOS-only constraint -> later CMOS/NMOS work Both continuations are real, traceable threads in this project's own content. This step names them and stops, consistent with house style's honest-handoff rule.

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