Taiwan Semiconductor Manufacturing Comp. Ltd.

Kuei-Jen Chang

Yuan-Ko Hwang

Tsung-Chi Hsieh

Juei-Wen Lin

Sen-Fu Chen

Hung-Hsin Liu

Shih Chiung Chen

Jen-Yung Tseng

A method of forming very small silicon nitride spacers in split-gate flash EPROMs is disclosed which prevent the occurrence of 'write disturb', unwanted reverse tunneling, or erasing. This is accomplished by forming spacers with well-controlled dimensions and well-defined shapes through a judicious use of a fully wet etch technique, including main-etch and over-etch. The use of a phosphoric acid solution in combination with sulfuric acid+hydrogen peroxide widens the process window from a few seconds to several minutes so that the small-dimensioned silicon nitride spacers can be better controlled than it has been possible in the past. In the first embodiment phosphoric solution is used both for main-etch and for over-etch. In the second embodiment, phosphoric solution is used for main-etch only, while the sulfuric+hydrogen peroxide solution is used as an over-etch in forming the tiny silicon nitride spacers of the invention. In the third embodiment, the step of over-etching of the spacers is combined with the step of stripping off of an implant photomask, thus, shortening the manufacturing product cycle.

Method of forming tiny silicon nitride spacer for flash EPROM by fully wet etching technology

A method for in-situ descum/hot bake/dry etch a polyimide photoresist layer and a passivation layer in a singe process chamber is disclosed. A process chamber that can be used for conducting in-situ a descum, a hot bake and a dry etch process sequentially in the same chamber is also disclosed. In the method, a process chamber equipped with a wafer platform and a wafer backside heating and cooling device is first provided, followed by the step of positioning a wafer that has a passivation layer and a patterned polyimide photoresist layer on top of the platform. An oxygen plasma is then generated in the chamber cavity to conduct a descum process, followed by flowing a heated inert gas onto a backside of the wafer to conduct a hot bake process. A cooling inert gas is then flown onto the wafer backside and an etchant gas is flown into the chamber to conduct a dry etch process for forming a via opening in the wafer.

Method and apparatus for in-situ descum/hot bake/dry etch photoresist/polyimide layer

A process for creating a fuse structure opening in a stack of materials comprised with overlying dielectric layers, and comprised with an underlying polysilicon layer, to expose a conductive fuse structure, has been developed. The process initiates with a dry etching procedure used to create an initial fuse structure opening in the dielectric layers, using a photoresist shape as an etch mask. Subsequent removal of the photoresist shape results in the completion of the fuse structure opening via in situ etching of the polysilicon layer exposed in the initial fuse structure opening. The isotropic wet etch procedure used for photoresist removal and in situ patterning of polysilicon, avoids polysilicon spacer formation on the sides of the conductive fuse structure, which would have been present with the use of an all dry etch procedure. In addition the wet etch procedure selectively terminates on a thin silicon oxide layer, located on the underlying conductive fuse structure.

Method of etching a polysilicon layer during the stripping of the photoresist shape used as an etch mask to create an opening to an underlying fuse structure

A protective tape is applied to the device side of a wafer (to protect it during an operation to grind the back side of the wafer) after the surface has been prepared to present only sloping surfaces to the tape. This profile prevents the otherwise sharp edges of the holes for the bonding pads from cutting into the adhesive of the tape and causing adhesive particles to remain on the wafer surface after the tape has been removed. Particles of resist can interfere with attaching wires to the bonding pads. The tape receiving surface of the wafer is commonly formed by a passivation layer and by bonding pad sites that are exposed through holes in the passivation layer. These sloping profiles can be formed by giving a sloping profile to the holes in the photoresist before the holes are etched. Alternatively the holes can be etched suitably wider at the top than at the bottom.

Growing community of inventors

Hsin-Chu, Taiwan

Kuei-Jen Chang