United Microelectronics Corp.

Wood Wu

Kun-Luh Chen

Heng-Sheng Huang

Hsin-Li Chen

Heng Sheng Huang

Han-Shen Lo

A process of fabricating a semiconductor device on a substrate with closely spaced high density conductive lines is provided. A thin insulating layer is formed on the surface of a substrate. Next, a blanket conductive layer and a blanket masking layer are deposited over the first insulating layer. Using conventional photolithography processes and plasma etching, elongated spaced parallel masking lines with vertical sidewalls are formed in the masking layer. A blanket polycrystalline silicon layer is deposited on the masking lines and the exposed areas of the conductive layer. Next, the blanket polycrystalline silicon layer is anisotrophically etched to form spacers on the vertical sidewalls of the masking lines. A second planarized masking layer is formed over the spacers and masking lines. The polycrystalline silicon spacers and the underlying first polycrystalline silicon layer are anisotrophically etched to form the closely spaced conductive lines in the first polycrystalline silicon layer. A coating of electrically isolating material is formed between and over the conductive lines.

Process for producing high density conductive lines

A ROM IC includes an extra bit line. The extra bit line outputs a first binary logic signal when a word line in a no-use area is attempted to be read and a second binary logic signal when a word line in a use area is attempted to be read. The output of the extra bit line overrides the normal output of the ROM when a word line in a no-use area is attempted to be read, so that the output of a read operation in the no-use area is always a predetermined binary value. This predetermined binary output value occurs in spite of the fact that because of a defect the actual logic value of a storage location in the word line to be read in the no-use area is other than a desired value. When a word line in the use area is read, the output of the extra bit line does not override the actual binary value stored in the word line. Using the extra bit line and associated override circuitry, a ROM IC with a few defects in a no-use area may still be used in an application. It should be noted that the addition of the extra bit line in the ROM does not significantly increase the amount of chip 'real estate' occupied by the ROM.

Bypass scheme for ROM IC

A process of fabricating a non-volatile read only memory device (ROM) wherein the conductive word lines have desirable very narrow widths and are closely spaced. The invention provides a process for forming word lines with a smaller width and line pitch than is possible with conventional processes. A first set of word lines is formed. Next, a second set of word lines is formed in between the first word lines using oxide spacers to define the second word lines.

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Hsin-Chu, Taiwan

Wood Wu