METHOD OF FORMING CHALCOGENIDE-BASED THIN FILM BY ATOMIC LAYER DEPOSITION AND METHOD OF FABRICATING MEMORY DEVICE USING THE CHALCOGENIDE-BASED THIN FILM

Smart overview of the Invention

The patent describes a method for forming a chalcogenide-based thin film using atomic layer deposition (ALD). This process is particularly relevant for the fabrication of memory devices, especially those utilizing Ovonic threshold switching (OTS) materials. The method involves alternating cycles of depositing germanium-selenium (Ge—Se) and antimony-selenium (Sb—Se) layers on a substrate. This approach aims to improve the uniformity and step coverage of the thin films, which are crucial for high-performance memory devices.

Deposition Process

The process begins with a first cycle where a Ge—Se layer is formed by introducing a germanium precursor, selenium precursor, and a C1-C4 alcohol as co-reactants into a reaction chamber containing the substrate. The germanium precursor includes an alkylamine group, while the selenium precursor contains an alkylsilyl group. The second cycle involves forming an Sb—Se layer using an antimony precursor with an alkoxide group, the same selenium precursor, and a C1-C3 alcohol. Each cycle can be repeated multiple times, with subcycles ranging from 1 to 10, to achieve the desired film thickness and composition.

Fabrication of Memory Devices

The method also details the fabrication of memory devices using the chalcogenide-based thin film. A stack structure of alternating conductive and insulating layers is formed on a substrate. A through-hole is created through this stack, and the chalcogenide layer is deposited on the side walls of the through-hole using the described ALD method. The hole is then filled with a conductive material, completing the structure necessary for the memory device.

Applications and Benefits

This method is particularly suited for creating storage class memory (SCM) devices, such as selector only memory (SOM) devices. These devices benefit from the improved film uniformity and step coverage provided by the ALD process. The chalcogenide-based thin films are essential for controlling the threshold voltage and ensuring low off-current, which are critical for the performance and efficiency of SOM devices.

Conclusion

The described method offers a significant advancement in the deposition of chalcogenide-based thin films for use in advanced memory devices. By utilizing atomic layer deposition, the method ensures a more uniform and consistently composed thin film, addressing the limitations of traditional deposition techniques like physical vapor deposition. The approach is poised to enhance the integration and performance of next-generation memory technologies.