Method for manufacturing flash memory

Abstract

The invention discloses a method for manufacturing a flash memory. The method includes the steps of providing a semiconductor lining, wherein the semiconductor lining comprises a flash memory unit area and a logic circuit area; depositing a grid material layer on the semiconductor lining, etching the portion, in the flash memory unit area, of the grid material layer to form a control grid; forming a bottom anti-reflection layer and a first photoresist layer on the semiconductor lining, removing the portion, in the logic circuit area, of the first photoresist layer to keep the portion, in the flash memory unit area, of the first photoresist layer; forming a second photoresist layer on the exposed bottom anti-reflection layer and the exposed first photoresist layer. According to the method, the control grid is covered with the two photoresist layers, and therefore the problem that the control grid in the flash memory unit area is damaged in the technological process of etching and forming a logic grid circuit is solved, the overall performance of the flash memory is improved, and the yield of the flash memory is increased.

Description

technical field [0001] The invention relates to a semiconductor manufacturing process, in particular to a method for making a flash memory. Background technique [0002] Memory is used to store a large amount of digital information. According to recent surveys, memory chips account for about 30% of semiconductor transactions worldwide. Over the years, technological progress and market demand have led to more and more high-density various Types of memory, such as RAM (random access memory), DRAM (dynamic random access memory) and FRAM (ferroelectric memory), etc. [0003] Random access memory, such as DRAM and SRAM (static random access memory), has the problem of data loss after power failure during use. To overcome this problem, various nonvolatile memories have been designed and developed. Recently, flash memory based on floating gate concept has become the most general non-volatile memory due to its small cell size and good performance. [0004] The non-volatile memory...

AI Technical Summary

Problems solved by technology

However, the thinner thickness of the photoresist in ArF lithography does not prevent damage to the underlying flash memory area

[0011] The traditional methods to solve the above problems are: (1) increase the thickness of the photoresist layer or / and bottom antireflection coating during the etching process, but it is not suitable for small-sized flash memory structures, which will affect the photoresist layer and the thickness of the bottom anti-reflective coating. The resolution of the logic gate formed under the bottom anti-reflective coating, such as critical dimensions affecting the gate line width and gate spacing; (2) using a hard mask layer, which is used as an etch protection layer to cover the control gate , the material of the hard mask layer can be silicon nitride or silicon oxynitride, but it is not suitable for the flash memory structure, because the etchant will damage the control gate when the hard mask layer is removed by etching

Therefore, the traditional solution will cause new process problems, easily introduce other impurities, and complicate the manufacturing process

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