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Publication Date: 2009-Jul-08

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New Te-Si Binary Precursors for Phase Change Memory Applications

              Disclosed herein are non-limiting embodiments of compositions and methods for depositing a precursor on a substrate.

The use of binary element compounds as CVD/ALD precursors has advantages relative to single element precursors in terms of the control of elemental composition of resultant film materials. Especially for GST film deposition, Ge2Sb2Te5 stoichiometric film is the most provable candidate for phase change memory application than other compositions, such as GeSb2Te4 and GeSb4Te7.

The molecules described in this ID will enable to deposit tellurium-containing films, such as GST, in thermal mode.

Besides, the presence of Si in the GST films was proved to increase the electrical characteristic of the films.

Currently, several memory makers reported phase change memory (PCM) as one of promising next generation of memory devices. This type of memory is very attractive as it is fast, has a long retention time, and is scalable for next generation devices. The principle is that the chalcogenide alloy is heated above its melting point (around 600C), and the way it is cooled down will lead to whether an amorphous or crystalline material, each of this state will represent the digital signal 0 or 1.

Several researches of 2~4 element containing layers (GeSbTe, GeSbInTe, GaLaS…) as chalcogenide materials in PCM applications have been carried out by many teams. Especially, Ge2Sb2Te5 films are widely studied because of the material’s low melting temperature for the phase change. A constant and exact value of the ratio of elements inside such chalcogenide materials is required in order to control the film properties.  

The physical vapor deposition (PVD, sputtering method) is used to deposit the chalcogenide alloy in M-bit size samples now, but the use of PVD should be avoided because of the inherent difficulties to deposit uniform films in deep trenches that are present in the G-bit size memories. For such small patterns, chemical vapor deposition (CVD) and/or the atomic layer deposition (ALD) are essential techniques to make small sized PCM devices.

Few CVD (ALD) methods are reported mainly Korean researchers.

R.-Y. Kim et al. (KAIST) reported CVD of GST film using Ge(C3H5)4, Sb(i-Pr)3, and Te(i-Pr)2 at 10~50Torr. The deposited films have rough surface and hexagonal structure.   (Appl. Phys. Lett., 89, 102107, 2006)

J. Lee et al. @ Samsung reported plasma enhanced ALD can improve film quality for GST film deposition using Ge source (GeMe4, Ge(NMe2)4, Ge{N(SiMe2)2}4), Sb source (Sb(NMe2)3, Sb{N(SiMe2)2}3) and Te(i-Pr)2 with plasma activated hydrogen. (Appl. Surf. Sci., 253, 3936, 2007)

B. J. Choi et al.@ Hynix reported PECVD GST film formation using Ge(i-Bu)4, Sb(i-Pr)3 and  Te(i-Pr)2 with H2.

The several Te precursor...