Semiconductor memory device having bipolar transistor

摘要

In a memory cell array, memory cells are formed in a matrix. Bit lines are formed to be connected to prescribed memory cells. Emitters of bipolar transistors are connected to bit lines. Bipolar transistors have their bases connected to each other, and further to precharge signal control means. Collector regions of bipolar transistors are connected to a power supply node. Bipolar transistors have a base region formed by introducing a p type impurity to the entire main surface of the semiconductor substrate, and n type impurity concentration included in the collector region immediately below the base region is at most 5x1018 cm-1. Consequently, a semiconductor memory device having a bipolar transistor which is capable of high speed operation and having high reliability can be manufactured at low cost.