Memory device and fabrication method thereof

Abstract

The present invention relates to a memory device and the fabrication method thereof. A plurality of pairs of floating gates and a plurality of pairs of select gates are formed above each active region. After forming a dielectric layer on each floating gate and on each select gate, a plurality of pairs of word lines and a plurality of pairs of source lines are formed simultaneously. The word lines and the source lines are disposed in a direction vertical to the strip active regions. A plurality of source / drain regions is disposed in the substrate beside the word lines and the source lines. After forming a thick dielectric layer over the substrate, a plurality of source line contacts are formed in the thick dielectric layer for connecting the source / drain regions that are between each pair of source lines and at least connecting one of each pair of the source lines.

Description

CROSS-REFERENCE TO RELATED APPLICATION [0001] This application is a divisional of a prior application Ser. No. 10 / 708,666, filed Mar. 18, 2004, which is a continuation-in-part of a prior application Ser. No. 10 / 707,016, filed Nov. 14, 2003.BACKGROUND OF THE INVENTION [0002] 1. Field of Invention [0003] The present invention relates to a semiconductor device and the fabrication method thereof. More particularly, the present invention relates to a memory device and the fabrication method thereof. [0004] 2. Description of Related Art [0005] The flash memory device allows multiple and repetitive writing, reading and erasure operations, and the storage data are retained even after the power supply is discontinued. Because of the aforementioned advantages, the flash memory has become the mainstream non-volatile memory device, which is widely applied in the electronic products, such as, personal computers, digital cameras and personal digital assistants (PDAs) etc. [0006] At present, the c...

AI Technical Summary

Benefits of technology

[0010] The invention provides a memory device and the fabrication method thereof, in which no extra contacts are required for reducing the resistance of the source line.

[0011] The invention provides a memory device and the fabrication method thereof, which avoids the problems of varying electrical properties for different memory cells, caused by corner rounding of the isolation structures.

[0015] According to the preferred embodiments, the source line of the present invention does not occupy the chip area. Further, according to the fabrication method described in the preferred embodiments, no extra contacts are needed to reduce the resistance of the source lines. In addition, according to the fabrication method described in the preferred embodiments, the prior problems of unequal electrical properties arising from the corner rounding can be alleviated.

Problems solved by technology

Since an extra doping process is performed to the active region 104 of the substrate 100 to form the source line 170, the fabrication processes become more complicated and costly.

As mentioned above, the prior art flash memory structure usually occupies more chip areas and hinders high integration of the device.

However, due to many uncontrollable factors of photolithography, corner rounding often occurs to the rectangle isolation structures 102 during the photolithography process.

Nonetheless, the distance between two adjacent memory cells is increased, leading to consuming more chip areas and preventing the device from having higher level of integration.

Images