Novellus Systems Incorporated

Advanced Micro Devices Corporation

Synergy Semiconductor Corporation

Atiye Bayman

Vishal Gauri

Weijie Zhang

Bart Jan Van Schravendijk

George D Papasouliotis

Vikram Singh

Md Sazzadur Rahman

Mammen Thomas

George D Papasoulitotis

Larry Joseph Pollock

Mayasari Lim

Larry J Pollock

Yong Ling

High density plasma chemical vapor deposition and etch back processes fill high aspect ratio gaps without liner erosion or further underlying structure attack. The characteristics of the deposition process are modulated such that the deposition component of the process initially dominates the sputter component of the process. For example, reactive gasses are introduced in a gradient fashion into the HDP reactor and introduction of bias power onto the substrate is delayed and gradually increased or reactor pressure is decreased. In the case of a multi-step etch enhanced gap fill process, the invention may involve gradually modulating deposition and etch components during transitions between process steps. By carefully controlling the transitions between process steps, including the introduction of reactive species into the HDP reactor and the application of source and bias power onto the substrate, structure erosion is prevented.

Process modulation to prevent structure erosion during gap fill

A method for process optimization to extend the utility of the HDP CVD gap fill technique modifies the characteristics of the HDP process (deposition and sputter components) in a dynamic mode in the course of filling a trench with dielectric material. As a result, the amount of dielectric deposited on the sidewall of the trench relative to that deposited at its bottom can be reduced and optimally minimized, thus improving the gap fill capability of the process. The dynamic modification of process characteristics provides enhanced process performance, since the optimization of these characteristics depends upon structure geometry, which is constantly changing during a gap fill operation. During the course of the gap fill operation, either at one or more discrete points or continuously, the evolution of the feature geometry is determined, either by direct measurement or in accordance with a growth model. The deposition process is modified to optimize the characteristics to the partially-filled feature geometry, and further filling the partially-filled feature using the modified deposition process is conducted. The process modification, including the geometry determination, and further filling with optimized process characteristics is optionally repeated until the gap is filled. In semiconductor manufacture, the invention relates to HDP CVD processes used to deposit IMD, ILD, or STI films for gap fill applications.

Dynamic modification of gap fill process characteristics

Chemical vapor deposition processes are employed to fill high aspect ratio (typically at least 3:1), narrow width (typically 1.5 microns or less and even sub 0.15 micron) gaps with significantly reduced incidence of voids or weak spots. This deposition process involves the use of hydrogen as a process gas in the reactive mixture of a plasma containing CVD reactor. The process gas also includes dielectric forming precursor molecules such as silicon and oxygen containing molecules.

Gap fill for high aspect ratio structures

Bipolar devices on a common substrate are formed in tubs defined by a sinker that is self-aligning with the isolating trench and provides a relatively low vertical resistance contact from a surface contact to the underlying buried layer. In a first embodiment, the isolating trench initially is defined only down to the top surface of the buried layer. The trench walls are then doped, and the dopant allowed to diffuse laterally through the trench sidewalls. The resultant sinker is self-aligned with the isolating trench. The trench depth is then further increased to a desired depth preferably penetrating into the substrate. Thereafter, a bipolar device is formed in the tub, preferably with the device collector adjacent the trench and thus aligned with the sinker. In a second embodiment, an opening is formed in the surface oxide defining the area where the trench (when formed) will be cut. The opening is then used to diffuse dopant into the sinker, the dopant diffusing downward through the epitaxial layer to the buried layer, and also diffusing somewhat laterally. The trench is then cut in a single step through the epitaxial layer and the buried layer and into the underlying substrate, cutting directly through the region in which the sinker has been previously diffused. However, because of the lateral sinker diffusion, a portion of the heavily doped region (e.g., the sinker) remains, and is self-aligned with the edges of the tub defining trench.

Process for making a self-aligned bipolar sinker structure

A sinker which is self-aligned with the oxide isolating trench which is used to define the tub in which the complete bipolar device is located. In a preferred approach to the process for forming the sinker of this invention, little additional diffusion of the sinker occurs during subsequent processing, whereby an effective sinker, aligned with the collector of the bipolar device, is achieved without additional masking steps.

Bipolar sinker structure and process for forming same

A plasma etching composition is set forth which comprises chlorine in an amount from about 40% to about 90%, a shape modifier species in an amount from about 10% to about 60%, and an etching selectivity enhancer in an amount sufficient to render the composition at least about 10 times as effective for etching a wafer as for etching a masking layer, the above percents being by mole. The composition is useful for plasma etching of a semiconductor wafer masked with a masking layer having an opening therethrough exposing a portion of the wafer which is to be etched in order to form a depression of a desired depth. This allows depressions of increased depth to be formed in wafers without increasing the thickness of the masking layer.

Plasma etch process for single-crystal silicon with improved selectivity

A semiconductor wafer masked with a masking layer having an opening therethrough exposing a portion of the wafer which is to be etched to form a depression of a desired depth is etched via a first plasma etching step under high bias voltage-high energy conditions with a plasma which includes chlorine and a shape modifier species, e.g., argon, to a first depth which is less than the desired depth. Thereafter, the depression is treated by a second plasma etching step under low bias voltage-low energy plasma etching conditions with a plasma which includes chlorine and is substantially free of the shape modifier species. A wet chemical etch follows to remove damaged silicon and impurities. The resulting depression has relatively straight walls and is relatively free of cusps and apexes. The depression is formed quickly and has a desired shape while only a minimal amount of damage and impurities are introduced into the wafer.

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Atiye Bayman