METHOD OF CONTROLLING OXIDE THINNING IN AN EPROM OR FLASH MEMORY ARRAY IN EPROM OR FLASH MEMORY ARRAY

摘要

There is provided a method of fabricating an electrically programmable read only memory (EPROM) or flash memory array structure to control oxide thinning to prevent shorting and trenching of bit lines in the array. The present invention includes the following steps. First, a layer of gate oxide, poly 1, ONO, poly cap and nitride is sequentially deposited on a substrate according to conventional processing techniques. Subsequently, a thin poly layer is deposited on the nitride layer in accordance with the present invention. The thin film poly / nitride / poly cap / ONO / poly layer is then etched to establish parallel strips of thin film poly / nitride / poly cap / ONO / poly 1. Next, a spacer oxide layer is formed on the end layer. Subsequently, the thin film poly layer and the substrate are subjected to a uniform subsequent etching of the spacer oxide and the end oxide layer until exposed. Subsequently, an N-type dopant is introduced into the germanium material between the thin film poly / nitride / poly cap / ONO / poly 1 strip to establish the N + buried bit line of the array. Optionally, a thin layer of the end oxide may be formed on the substrate prior to introducing the dopant. A buried bit line is formed and then a differential oxide layer is deposited over the structure and the process is continued according to conventional steps.