Abstract:
A power Schottky rectifier device and its fabrication method are disclosed. The method comprises the following steps: First, a semiconductor substrate having a relatively heavily doped n+ doped layer and a lightly doped is provided. A buried p region is then formed in the epi layer by ion implantation. Afterward, a first oxide layer and a nitride layer are then successively formed on the epi layer. The result structure is then patterned to form trenches. Subsequently, a thermal oxidation step is performed to recover etch damage. A wet etch is then performed to remove the thin oxide layer in the trench to expose the silicon in the sidewall. After that, a silicidation process is then performed to form silicide layer on the n-epi-layer in the trenches. After a removal of un-reacted metal layer, a top metal layer is then formed on the silicide layer and on the first oxide layer or nitride layer. The top metal layer on the termination region portion is then patterned to define anode. Finally, after backside layers formed on the rear surface of the substrate are removed, another cathode layer is formed on the rear surface.
Abstract:
A Schottky diode structure and a method of making the same are disclosed. The method comprises following steps: firstly, a semiconductor substrate having a first conductive layer and an epi-layer doped with the same type impurities is provided. Then a first oxide layer is form on the epi layer. A patterning step to pattern first oxide layer and recess the epi layer (optional) is then followed to define guard rings. After stripping the photoresist pattern, a polycrystalline silicon layer formation is then followed. A boron and/or BF2+ ion implant is then performed. Subsequently, a high temperature drive in process and oxidation process to oxidize the polycrystalline silicon layer and drive ions is then carried out. A second mask and etch steps are then performed to open the active regions. A metallization process is then done. A third mask and etch steps are then implemented to define anode. Finally, a backside metal layer is then formed and serves as a cathode.
Abstract:
The method for forming an isolation region in the present invention mainly includes the following steps. First, a pad layer is formed on a semiconductor substrate and an oxidation masking layer is formed on the pad layer. The oxidation masking layer, the pad layer, and the substrate are then patterned to form trenches in the substrate. The pad layer is removed laterally to form undercut structures under the oxidation masking layer. A doped layer is conformably formed on the oxidation masking layer, the undercut structures of the pad layer, and the substrate in the trenches. Next, a thermally oxidizing step is carried out to oxidize the doped layer to form an oxidized layer conformably on the oxidation masking layer, the undercut structures of the pad layer, and the substrate in the trenchs. A dielectric layer is formed over the substrate to fill up the trenches and cover over the pad layer and the oxidation masking layer. The dielectric layer is planarized downward to portions of the oxidation masking layer. Finally, the oxidation masking layer and the pad layer are removed.
Abstract:
The method of the present invention is to fabricate a CMOS device without boron penetration. A nitrided gate oxide and SAS gate electrode are provided to suppress boron penetration. The nitrided gate oxide could be formed in two approaches. One of the approaches is to implant nitrogen ions into the interface between substrate and pad oxide layer, and then thermally treat the substrate for segregating the doped nitrogen ions in the surface of substrate. Removing the pad oxide layer, thermally treating the substrate in oxygen ambient for growing a gate oxide layer, the nitrided gate oxide layer is formed by incorporating doped nitrogen ions into the growing gate oxide layer. The other approach is to place the substrate having a gate oxide layer thereon in nitrogen plasma ambient, thereby forming the nitrided gate oxide layer. After the formation of nitrided gate oxide layer, at least one stacked amorphous silicon (SAS) layer is formed over the gate oxide layer. The gate structure is formed by patterning the SAS layer and nitrided gate oxide layer. Thereafter, source/drain with LDD regions are subsequently formed in the substrate. Finally, a thermal treatment is performed to convert the stacked-amorphous silicon gate into poly silicon gate and to form shallow source and drain junction in the substrate, thereby achieving the structure of the MOS device.
Abstract:
The method for forming flash memory includes the following steps. At first, a semiconductor substrate with an isolation region formed upon is provided. The semiconductor substrate has a pad oxide layer and a first nitride layer formed over. A portion of the first nitride layer and of the pad oxide layer are removed to define a gate region. A first oxide layer is formed and then a sidewall structure is formed. The semiconductor substrate is doped with first type dopants. A first thermal process is performed to form a second oxide layer and drive in the first type dopants. The sidewall structure and the first nitride layer are then removed, and the first oxide layer is removed to expose a portion of the substrate under the first oxide layer. Silicon grains are formed on the pad oxide layer, the exposed portion of substrate, and the second oxide layer. The exposed portion of the substrate is then etched to leave a rugged surface on the exposed portion of the substrate. A second thermal process is performed to form a tunnel oxide layer on the rugged surface. A first conductive layer is formed over the substrate and a portion of the first conductive layer is removed to define a floating gate. A dielectric layer is formed over the semiconductor substrate and a second conductive layer is then formed over as a control gate.
Abstract:
In the preferred embodiment for forming a ragged polysilicon crown-shaped capacitor of a dynamic random access memory cell, a first dielectric layer is formed on a semiconductor substrate. A portion of the first dielectric layer is removed to define a contact hole within the first dielectric layer, wherein the contact hole is extended down to a source region in the substrate. Next, a conductive plug is formed and communicated to the source region within the contact hole. A second dielectric layer is formed on the first dielectric layer and the conductive plug, and a third dielectric layer is formed on the second dielectric layer. Next, portions of the third dielectric layer and the second dielectric layer are removed to define a storage node opening, wherein the storage node opening is located over the conductive plug. A first conductive layer is then formed to conformably cover the inside surface of the storage node opening and on the third dielectric layer. A fourth dielectric layer is formed on the first conductive layer and the substrate is planarized to the surface of the third dielectric layer. The fourth dielectric layer and the third dielectric layer are then removed to leave a storage node which is composed of the first conductive layer. Finally, a fifth dielectric layer is formed on the storage node, and a second conductive layer is then formed on the fifth dielectric layer to finish the capacitor structure.
Abstract:
The present invention proposes a method for fabricating high-density and high-speed NAND-type mask read-only memories. This method constructs the doped sources and drains by dopant diffusion into the silicon substrate to form ultra-shallow junction, and therefore minimizes the punch-through issue. First, a stacked thin oxide, doped silicon and silicon nitride layer is deposited on the semiconductor substrate and then bit line regions is defined. Gate oxide film is formed between the bit line regions and the dopants in the silicon layer are driven into the substrate to form shallow junctions for source and drain regions. A doped polysilicon layer is deposited on the substrate and a chemical mechanical polishing process is carried out with the silicon nitride as the stopping layer. A coding implantation is performed and a conductive layer is defined on the polysilicon layer to be the word lines. A high temperature annealing is carried out to form polycide in the word line regions, thereby finishing the fabrication.
Abstract:
The present invention provides a mask ROM memory to minimize band-to-band leakage. The substrate includes a normal NMOS device region and a NMOS cell region for coding. An isolation region is formed between the normal NMOS device region and the NMOS cell region. A gate oxide layer is formed on the normal NMOS device region and a coding oxide layer is formed on the NMOS cell region, respectively. In the preferred embodiments, the coding oxide layer has a thickness of about two to ten times that of the gate oxide layer. Main gates are respectively formed on the gate oxide layer and the coding oxide layer. In the present invention, the main gates comprise materials like metal and metal compounds. Spacers are formed on the side walls of the main gates. First doped regions of source and drain regions, or namely lightly doped drains (LDD) and sources, are formed under the spacers and are adjacent to the main gates. Second doped regions of the source and drain regions are formed next to and outside the first doped regions. The second doped regions have a heavier dose than the first doped regions. A p type doped region is formed under the coding oxide layer and adjacent to a surface of the NMOS cell region. The p type doped region is doped with dopants like aluminum-containing, gallium-containing, indium-containing, or thallium-containing dopants. The p type doped region has higher resistance than the other normal NMOS devices during the operation.
Abstract:
A method of fabricating high density multiple states mask ROM cells on a semiconductor substrate is disclosed. The method comprises the following steps. Firstly, the array of buried bit line is formed on semiconductor substrate. Then, a CVD oxide film is deposited on said substrate. The first coding mask is applied to dip out the CVD oxide film on the uncoded regions. Then, a thin gate oxide film is thermally grown on said substrate. At the same time, the CVD oxide film is densified and the N+source/drain junction of buried bit lines is formed. A conductive layer is then deposited on all area followed by defining the word lines. The second coding process is performed by using a high energy boron ion implantation through the conductive layer and gate oxide film into said predetermined regions. By combination of the first CVD oxide coding process and the second boron ion implantation coding process, a high density mask ROM with a multiple states is fabricated.
Abstract:
A MOSFET includes a gate oxide formed on a substrate. A thin dielectric layer is formed on the side walls of the gate. A gate is formed on the gate oxide. A first metal silicide layer is formed on top of the gate to increase the conductivity of the gate. Spacers are formed on the substrate and are separated with the gate by a space. Air gaps are formed between the gate and the spacers. First doped ion regions are formed aligned to the air gaps in the substrate, under a portion of the dielectric layer. Second doped ion regions are formed under the spacers in the substrate, next to the first doped ion regions. Third doped ion regions are formed in the substrate next to the second doped ion regions. The third doped ion regions have relatively highly doped ions to the first doped ion regions. The second doped ion regions are formed with immediately highly doped ions between the first and the third doped ion regions.