Macronix International Co., Ltd.

Tahorng Yang

Ching-Yu Chang

Henry Chung

Cheng-Chen Calvin Hsueh

Tsung-Hsien Wu

A fabrication method for a read only memory provides a substrate having a memory cell region and a periphery circuit region. A memory cell region has a memory cell array and the periphery circuit region has transistors. A precise layer having a plurality of first openings is formed in the memory cell region. The first openings are above the channel region of each memory cell in the memory cell array and the critical dimension of the first openings is identical. A mask layer having second openings and third openings is formed on the substrate. The second openings locate over a pre-coding memory cell region, and the third openings locate over the transistor gates. An ion implantation is performed to code the memory cell in the pre-coding memory cell region and to adjust the threshold voltage of the transistor, using the precise layer and the mask layer as a mask.

Method for fabricating read only memory including a first and second exposures to a photoresist layer

A method of forming holes in a layer through a cross-shape image exposure. The method includes removing a section from each corner of the rectangular patterns on a photomask to form cross-shape patterns so that circular or elliptical contact holes are formed on a photoresist layer after photo-exposure and development. Optical image contrast between contacts is increased by the cross-shape patterns on the photomask.

Hole forming by cross-shape image exposure

Method for fabricating read only memory including forming masking layers with openings and pre-coding the cell and peripheral regions

A method is used to form an insulating layer with foamed structure. About the method, a gel layer over a substrate, where the gel layer includes several types of solution, an unextractable material, and a solvent. The substrate is then put in a closed pressure chamber. The closed pressure chamber is heated to a subcritical temperature with respect to the material which is included in the gel layer but to be extracted out. In this situation, liquid and the material to be extracted all turn to a vapor phase due to the pressure in the pressure chamber has reached the subcritical pressure, whereby materials are extracted. Under this temperature, the vapor is flushed away, and a noble gas is flushed into the pressure chamber for cleaning. The substrate with the gel layer is cooled down to the environmental temperature. Then the substrate is taken out from the pressure chamber.

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Hsinchu, Taiwan

Tahorng Yang