Chartered Semiconductor Manufacturing Ltd (corporation)

National University of Singapore

Chong Wee Lim

Soh Yun Siah

Eng Hua Lim

Chun Hui Low

Kong Hean Lee

Kin Leong Pey

Pei Ching Lee

Lap Chan

Kong-Hean Lee

Eng Hwa Lim

An improved and new process for fabricating MOSFET's in shallow trench isolation (STI), with sub-quarter micron ground rules, includes a passivating trench cap layer of silicon nitride. The silicon nitride passivating trench cap is utilized in the formation of borderless or &ldquo;unframed&rdquo; electrical contacts, without reducing the poly to poly spacing. Borderless contacts are formed, wherein contact openings are etched in an interlevel dielectric (ILD) layer over both an active region (P-N junction) and an inactive trench isolation region. During the contact hole opening, a selective etch process is utilized which etches the ILD layer, while the protecting passivating silicon nitride trench cap layer remains intact protecting the P-N junction at the edge of trench region. Subsequent processing of conductive tungsten metal plugs are prevented from shorting by the passivating trench cap. This method of forming borderless contacts with a passivating trench cap in a partially recessed trench isolation scheme improves device reliability since it prevents electrically short circuiting of the P-N junction and lowers the overall diode leakage. Furthermore, the use of the silicon nitride trench cap protects the underlying STI trench oxide during subsequent cleaning process steps. In addition, the nitride cap protects the STI oxide from excessive recess formation and prevents the exposure of STI seams, in addition to minimizing transistor junction leakage.

Silicon nitride capped shallow trench isolation method for fabricating sub-micron devices with borderless contacts

A new method is established to form different silicide layers over the top of the gate electrode and the surface of the source/drain regions. A thin layer of TiSi,is formed over the source/drain regions by depositing a layer of titanium and annealing this layer with the silicon substrate. The gate electrode is created as a recessed electrode, in the top recession of the electrode a layer of CoSi,is formed by depositing a layer of cobalt over the gate electrode. This layer of COSi,serves as the electrical gate contact point.

Optimized Co/Ti-salicide scheme for shallow junction deep sub-micron device fabrication

An improved and new process for fabricating MOSFET's in shallow trench isolation (STI), with sub-quarter micron ground rules, includes a passivating trench liner of silicon nitride. The silicon nitride passivating liner is utilized in the formation of borderless or &ldquo;unframed&rdquo; electrical contacts, without reducing the poly to poly spacing. Borderless contacts are formed, wherein contact openings are etched in an interlevel dielectric (ILD) layer over both an active region (P-N junction) and an inactive trench isolation region. During the contact hole opening, a selective etch process is utilized which etches the ILD layer, while the protecting passivating silicon nitride liner remains intact protecting the P-N junction at the edge of trench region. Subsequent processing of conductive tungsten metal plugs are prevented from shorting by the passivating trench liner. This method of forming borderless contacts with a passivating trench liner in a partially recessed trench isolation scheme improves device reliability since it prevents electrically short circuiting of the P-N junction and lowers the overall diode leakage. In addition, the use of this invention's semi-recessed STI process scheme helps to reduce the aspect ratio of the trench, thereby aiding the filling of the trench. Therefore, with the process described herein, STI oxide seam formation is eliminated.

Partially recessed shallow trench isolation method for fabricating borderless contacts

A method of fabricating shallow trench isolations has been achieved. A semiconductor substrate is provided. A pad oxide layer is grown overlying the semiconductor substrate. A silicon nitride layer is deposited. The silicon nitride layer and the pad oxide layer are patterned to form a hard mask. The openings in the hard mask correspond to planned trenches in the semiconductor substrate. A silicon dioxide layer is deposited overlying the silicon nitride layer and the semiconductor substrate. The silicon dioxide layer is anisotropically etched to form sidewall spacers on the inside of the openings of the hard mask. The semiconductor substrate is etched to form the trenches. The sidewall spacers are etched away. The semiconductor substrate is sputter etched to round the corners of the trenches. An oxide trench lining layer is grown overlying the semiconductor substrate. A trench fill layer is deposited overlying the silicon nitride layer and filling the trenches. The trench fill layer is polished down to the top surface of the silicon nitride layer. The silicon nitride layer is etched away. The trench fill layer and the pad oxide layer are polished down to the top surface of the semiconductor substrate to complete the shallow trench isolation, and the integrated circuit device is completed.

Method to form shallow trench isolations with rounded corners and reduced trench oxide recess

A method for forming a stepped shallow trench isolation is described. A pad oxide layer is deposited on the surface of a semiconductor substrate. A first nitride layer is deposited overlying the pad oxide layer. The first nitride layer is etched through where it is not covered by a mask to provide an opening to the pad oxide layer. A first trench is etched through the pad oxide layer within the opening and into the semiconductor substrate. A second nitride layer is deposited overlying the first nitride layer and filling the first trench. Simultaneously, the second nitride layer is anisotropically etched to form nitride spacers on the sidewalls of the first trench and the semiconductor substrate is etched into where it is not covered by the spacers to form a second trench. Ions are implanted into the semiconductor substrate underlying the second trench. The first and second trenches are filled with an oxide layer. Thereafter, the first nitride and pad oxide layers are removed completing the formation of shallow trench isolation in the fabrication of an integrated circuit device. This nitride spacer STI architecture prevents STI corner oxide recess and enables borderless contact formation. This unique process reduces junction leakage and also reduces contact leakage.

Method of making low-leakage architecture for sub-0.18 .mu.m salicided

A method for fabricating a deep sub-micron gate electrode, comprising polysilicon and metal, having ultra-low sheet resistance. The process begins by forming shallow trench isolation regions 14 in a silicon substrate 10. A gate oxide layer is formed on device areas. A doped blanket polysilicon layer 16 is formed on the gate oxide layer. A cap layer 20 composed of silicon nitride is formed on the polysilicon layer 16. The cap layer 20 and the polysilicon layer 16 are patterned by photoresist masking and anisotropic etching to form a bottom gate electrode 16A and a gate cap 20A. Lightly doped source/drain areas 22 are formed adjacent to the gate bottom electrodes 16A by ion implantation. Sidewall spacers 21 are formed on the gate electrode 16A and gate cap 20A. Source/drain regions 24 are formed by ion implantation adjacent to said sidewall spacers 21. A metal silicide 23 is formed on the source/drain regions 24. An interlevel dielectric layer (ILD) 28 is deposited and planarized by CMP using the gate cap 20A as a CMP stop. The gate cap 20 is selectively removed. A barrier layer 32 composed of a TaN, CoWP, TiN or W.sub.x N.sub.y is formed over the planarized IDL 28A. A top gate layer 36 composed of copper or tungsten is formed on the barrier layer 32. The top gate layer 36 and the barrier layer 32 are removed down to the level of the top of the ILD 28 using CMP; thereby forming a top gate electrode. A passivation layer 40, composed of Pd or NiP is selectively deposited over the gate top electrode 36A.

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Misia, Malaysia

Chong Wee Lim