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Alloying PNP Transistors

IP.com Disclosure Number: IPCOM000098543D
Original Publication Date: 1959-Feb-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Miller, WH: AUTHOR

Abstract

In this method employing the fast fire technique for alloying PNP transistors an open-ended furnace is preheated in an inert gas atmosphere at 1150 degrees C. One impurity pellet such as indium is placed on a base crystal of germanium within a container, and the container is then placed in the preheated furnace for from 20 to 30 seconds. This is the typical time required to bring the crystal to the alloying temperature of about 580 degrees C. The time is adjusted according to the size of the container, size of the base crystal, the frequency cut-off value desired, and the size of the dot to be fused. After this period the container is removed from the furnace and allowed to cool in air at room temperature of about 25 degrees C.

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Alloying PNP Transistors

In this method employing the fast fire technique for alloying PNP transistors an open-ended furnace is preheated in an inert gas atmosphere at 1150 degrees
C. One impurity pellet such as indium is placed on a base crystal of germanium within a container, and the container is then placed in the preheated furnace for from 20 to 30 seconds. This is the typical time required to bring the crystal to the alloying temperature of about 580 degrees C. The time is adjusted according to the size of the container, size of the base crystal, the frequency cut-off value desired, and the size of the dot to be fused. After this period the container is removed from the furnace and allowed to cool in air at room temperature of about 25 degrees C. The second impurity pellet is placed on the base crystal and placed within the furnace for a period less than the first period to minimize additional fusing of the first pellet. After the second heating, the fused crystal is again removed from the furnace and allowed to cool in air at room temperature to complete fabrication of the transistor.

This method of alloying provides for rapid fabrication and better transistor characteristics because of improved dot geometry. Quick arrival at the alloying temperature prevents spreading of the dot on the surface of the base crystal and the rapid cooling in air permits more uniform recrystallization to take place. Further, the oxide coating of the dot achieved by cooling in...