International Business Machines Corporation

Michael L Kerbaugh

John F Rembetski

Charles W Koburger, Iii

Paul Christian Parries

Donald M Kenney

David L Harmon

Brian J Machesney

Nancy T Pascoe

Jeffrey A Robinson

John Edward Cronin

Arup Bhattacharyya

Jerome Brett Lasky

Howard Smith Landis

William J Cote

Harold G Linde

Rosemary A Previti-Kelly

Ranee W Kwong

Carter W Kaanta

James Allan Bruce

Harbans S Sachdev

Francis Roger White

Michael A Leach

Robert M Quinn

Somanath Dash

Robert W Sweetser

Nitin B Parekh

Tanya N Lee

A semiconductor fabrication process for forming borderless contacts (130, 170, 172) using a removable mandrel (110). The process involves depositing a mandrel on an underlying barrier layer (100) designed to protect underlying structures (40) formed on a substrate (24). The mandrel is made from a material that will etch at a faster rate than the barrier layer so as to permit the formation of openings in the mandrel to be stopped on the barrier layer without penetrating such layer. After depositing a contact (130) in a first opening (120) formed in the mandrel, a second opening (140) is formed and a second contact (170) is deposited therein. Thereafter, the mandrel is removed and replaced with a layer of solid dielectric material (180).

Method of forming borderless contacts using a removable mandrel

An improved mask and method of forming a deep and width trench in a substrate and the resulting structure is disclosed. A substrate material such as silicon has deposited thereon a first layer of sacrificial material as a first component of an etch mask, the sacrificial material being a material such as polysilicon that is either etched by or absorbs the same ions which reactively ion etch the substrate. A second layer of material, which resists reactive ion etching, such as silicon dioxide, is deposited over the first layer of material as a second component of the etch mask. The silicon dioxide is patterned in the form of the trench to be formed in the substrate. The layer polysilicon material is then reactive ion etched and the reactive ion etching continued to form a trench in the silicon substrate. The polysilicon acts as a sacrificial material being etched by any ions that are reflected from the silicon dioxide or are directed at an angle such that they strike the layer of polysilicon material. Thus, only those ions which are directed essentially normal to the underlying substrate perform the trench etching. This allows the trench to have essentially straight side walls and to be of essentially uniform width.

Reactive ion etching buffer mask

A method of forming a planarized dielectric filled wide shallow trench in a semi-conductor substrate is provided. A layer of etch stop such as Si.sub.3 N.sub.4 is deposited onto the semi-conductor substrate, and wide trenches are formed through the Si.sub.3 N.sub.4 into the substrate by conventional RIE. The surface of the substrate including the trenches have formed thereon a SiO.sub.2 coating, conforming to the surface of the substrate. A layer of etch resistant material such as polysilicon is deposited onto the SiO.sub.2 material. The polysilicon outside the width of the trenches is then removed by chemical-mechanical polishing to expose the SiO.sub.2 there below, while leaving the SiO.sub.2 above the trenches covered with polysilicon. The exposed SiO.sub.2 is then RIE etched down to the Si.sub.3 N.sub.4, leaving a plug of SiO.sub.2 capped with the etch resistant polysilicon over each trench. These plugs are then removed by mechanical polishing down to the Si.sub.3 N.sub.4, to provide a planarized upper surface of SiO.sub.2 and Si.sub.3 N.sub.4 on the top of the substrate. The invention also is useful in forming planarized surfaces on substrates having trenches filled with conductive material.

Forming wide dielectric-filled isolation trenches in semi-conductors

An improved mask and method of forming a deep and uniform width trench in a substrate and the resulting structure is disclosed. A substrate material such as silicon has deposited thereon a first layer of sacrificial material as a first component of an etch mask, the sacrificial material being a material such as polysilicon that is either etched by or absorbs the same ions which reactively ion etch the substrate. A second layer of material, which resists reactive ion etching, such as silicon dioxide, is deposited over the first layer of material as a second component of the etch mask. The silicon dioxide is patterned in the form of the trench to be formed in the substrate. The layer polysilicon material is then reactive ion etched and the reactive ion etching continued to form a trench in the silicon substrate. The polysilicon acts as a sacrificial material being etched by any ions that are reflected from the silicon dioxide or are directed at an angle such that they strike the layer of polysilicon material. Thus, only those ions which are directed essentially normal to the underlying substrate perform the trench etching. This allows the trench to have essentially straight side walls and to be of essentially uniform width.

A process for forming a pattern on a substrate utilizing photolithographic techniques. In this process a layer of polymeric material containing a fluorine-containing compound is applied over the substrate and cured. A layer of photoresist material is applied over the polymeric material imagewise exposed and developed to reveal the image on the underlying polymeric material. Thereafter, the photoresist is silylated, and the structure is reactive ion etched to transfer the pattern to the underlying substrate. The fluorine component provides an underlying structure free of residue and cracking.

Fluorine-containing base layer for multi-layer resist processes

A conformal organic layer is used to define spacers on the sidewalls of an organic mandrel. The organic layer (e.g., parylene) can be deposited at low temperatures, and as such is compatible with temperature-sensitive mandrel materials that reflow at high deposition temperatures. The conformal organic material can be dry etched as the same rate as the organic mandrels, while being resistant to wet strip solvents that remove the organic mandrels. This series of etch characteristics make the organic mandrel-organic spacer combination compatible with a host of masking applications.

Process for defining organic sidewall structures

A method for self-aligning an isolation structure to a diffusion region. A first masking layer is formed on a semiconductor substrate, the first masking layer having at least one aperture sidewall which is substantially perpendicular to the semiconductor substrate. Dopant ions are implanted into the semiconductor substrate through the first masking layer to form a doped region. Sidewall spacers are then defined on the sidewalls of the aperture, and a sidewall image reversal process is carried out such that the sidewall spacers define trench apertures in a masking structure. Finally, isolation trenches are etched into the semiconductor substrate through the masking structure. Alternatively, the implantation step is carried out after the sidewall spacers are defined on the first masking layer.

Method of self-aligning a trench isolation structure to an implanted

Spacers are formed having widths that vary as a function of the spacing between the mandrels upon which the conformal material that defines the spacers is deposited and etched. As the spacing between adjacent mandrels decreases, the width of the resulting spacers decreases. The correlation between mandrel spacing and sidewall structure width is independent of the thickness of the conformal material as-deposited. As the spacing between the mandrels decreases, the decrease in width becomes more pronounced, particularly at mandrel spacings of five microns or less. Thus, by making adjacent mandrels closer together or further apart and adjusting mandrel height, active/passive components having differing widths/lengths may be formed from the same conformal layer.

Formation of variable-width sidewall structures

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Burlington, VT, United States of America

Michael L Kerbaugh