Abstract: The present disclosure relates to a MEMS package having different trench depths, and a method of fabricating the MEMS package. In some embodiments, a first trench in a first device region, a second trench in a second region, and a scribe trench in a scribe line region are formed at a front side of a cap substrate. Then, a hard mask is formed and patterned over the cap substrate. Then, a stopper is formed by performing an etch to the cap substrate such that a first portion of a bottom surface of the first trench uncovered by the hard mask is recessed while a second portion of the bottom surface of the first trench covered by the hard mask is non-altered to form a stopper within the first trench. Then, a second etch is performed to the second trench to lower the bottom surface of the second trench.

Abstract: In a method of manufacturing a semiconductor device including a non-volatile memory formed in a memory cell area and a logic circuit formed in a peripheral area, a mask layer is formed over a substrate in the memory cell area and the peripheral area. A resist mask is formed over the peripheral area. The mask layer in the memory cell area is patterned by using the resist mask as an etching mask. The substrate is etched in the memory cell area. After etching the substrate, a memory cell structure in the memory cell area and a gate structure for the logic circuit are formed. A dielectric layer is formed to cover the memory cell structure and the gate structure. A planarization operation is performed on the dielectric layer. An upper portion of the memory cell structure is planarized during the planarization operation.

Abstract: A method and system for controlling a silicon nitride etching bath provides the etching bath including phosphoric acid heated to an elevated temperature. The concentration of silicon in the phosphoric acid is controlled to maintain a desired level associated with a desired silicon nitride/silicon oxide etch selectivity. Silicon concentration is measured while the silicon remains in soluble form and prior to silica precipitation. Responsive to the measuring, fresh heated phosphoric acid is added to the etching bath when necessary to maintain the desired concentration and silicon nitride:silicon oxide etch selectivity and prevent silica precipitation. The addition of fresh heated phosphoric acid enables the etching bath to remain at a steady state temperature. Atomic absorption spectroscopy may be used to monitor the silicon concentration which may be obtained by diluting a sample of phosphoric acid with cold deionized water and measuring before silica precipitation occurs.

Abstract: A method of making the selection gate in a split-gate flash EEPROM cell forms a selection gate on a trench sidewall of a semiconductor substrate to minimize the sidewise dimension of the selection gate and to maintain the channel length. The disclosed method includes the steps of: forming a trench on a semiconductor substrate on one side of a suspending gate structure; forming an inter polysilicon dielectric layer on the sidewall of the suspending gate structure and the trench; and forming a polysilicon spacer on the inter polysilicon dielectric layer as the selection gate. Such a split-gate flash EEPROM cell can produce ballistic hot electrons, improving the data writing efficiency and lowering the writing voltage.