ALD and ALE Applications in 3D Monolithic Device Integration

Two-dimensional scaling of integrated circuits has been the backbone of Moore’s Law until recently. As feature sizes reach physical limits, new approaches are needed. Monolithic scaling in the third dimension is one of the solutions. NAND flash memory started to grow in the vertical direction in 2014 with just 24 layers of memory cells with 128Gbit storage. The fact that the industry is targeting 1000 layers only 10 years later is testament to the stunning success of vertical integration. Logic and dynamic random-access memories (DRAM) are also conquering the third dimension. The structures of these devices are very complicated and novel lateral integration involving conformal deposition and isotropic etching are key enablers. In this talk we will discuss examples of combined use of ALD and ALE to realize thin smooth and crystalline films, selective deposition and lateral stacked films. The etching can be performed using radical etch, thermal etch and thermal ALE depending on the process requirements.