Mask type read-only memory low heat budget making technology

Abstract

A mask-mode read-only memory low thermal budget manufacturing process provides a substrate with a gate oxide layer on it, and then forms a first conductor layer on the gate oxide layer, and then forms several bit lines in the substrate. Next, a second conductor layer is formed on the first conductor layer, and then several read-only memory codes are formed in the substrate.

Description

technical field [0001] The present invention relates to a mask read only memory (mask read only memory, referred to as Mask ROM) manufacturing process, and in particular to a mask read only memory low thermal budget (thermal budget) manufacturing process. Background technique [0002] Mask ROM is the most basic type of ROM. In the known manufacturing process of the masked ROM, a buried bit line is formed first, and then a gate oxide, a gate layer, etc. are formed. However, the formation temperature of the gate oxide layer is generally above 800 degrees Celsius, so the dopant in the bit line often has the problem of lateral diffusion due to such a thermal process. Moreover, as the size of semiconductor devices continues to shrink, the problem of lateral diffusion caused by the above-mentioned thermal fabrication process will become more serious. [0003] Therefore, a so-called "post-gate oxide" masked ROM manufacturing process is currently proposed, which mainly forms a gat...

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Problems solved by technology

[0004] However, although the above-mentioned "behind the gate oxide layer" manufacturing process can avoid the lateral diffusion problem caused by the thermal manufacturing process, it is much more complicated than the known method of forming the bit line first, and increases a lot of manufacturing cost and manufacturing process time

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