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GST etching process of phase change memory of plasma Cleaning Machine

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21 Dec,2020

GST etching process of phase change memory of plasma Cleaning Machine:

GST is a widely used phase change material, and its plasma cleaning machine etching process is unique to phase change memory.

1. Plasma cleaning machine GST etching gas screening

As the core material of PHASE-change memory, THE volume of GST directly affects the electrical performance of the device, so the integrity of GST films is very important. The influence of Cl, F and Br3 different halogen gases on GST etching profile of plasma cleaning machine was studied. The main etching agent containing bromine gas showed less damage to GST morphology than oxygen gas or fluorine gas. The Ar and He as dilution gas had less influence on the GST diagrammatic form, but in the graph with 4 wires as a set, the load of the edge and center graph was smaller when using He. When Ar is used, the load is relatively significant, and this difference may originate from the significant quality difference between Ar and He.

2. Hard mask (Titanium nitride) profile shape control

Titanium nitride is generally used as a hard mask for GST etching, and its profile shape directly affects the contour of the underlying GST. Chlorine gas (Cl) in the plasma cleaning machine is mostly used for titanium nitride etching. In the influence of adding BCl3 and He to chlorine gas on the profile shape of titanium nitride, it can be seen that although adding He can bring a higher optoresistance selection ratio, the etching surface of its titanium nitride is obviously more tilted than adding BCl3.

3. Post-etching treatment

In general, after dry etching such as plasma cleaning machine is completed, a step of acid or alkaline wet cleaning is introduced to completely remove the by-products formed by plasma etching on the wafer to avoid secondary reactions. GST is a kind of metal alloy, any acid or alkali will cause serious corrosion, so GST plasma etching can only use low concentration of acid (or alkali) wet cleaning agent, GST etching produced by the metal elements of the by-products cleaning effect is poor. As a result, a plasma cleaning machine after etching processing (Post Etch Treatment) technology was introduced, after complete the GST and remove photoresist etching, join step shorter for fluoride gas etching agent (CF4, SF6 and NF3) etching formula, using fluoride gas can activate the GST etching by-products characteristics, can obviously improve the effect of the wet cleaning.

plasma Cleaning Machine