https://www.diva-portal.org/smash/get/diva2:17175/FULLTEXT02

Ionized physical vapor deposition (IPVD): A review of technology and applications

Properties of Ga2O3 thin films deposited by electron‐beam evaporation from a high‐purity single‐crystal Gd3Ga5O12 source are reported. As‐deposited Ga2O3 films are amorphous, stoichiometric, and homogeneous. Excellent uniformity in thickness and refractive index was obtained over a 2 in. wafer. The films maintain their integrity during annealing up to 800 and 1200 °C on GaAs and Si substrates, respectively. Optical properties including refractive index (n=1.84–1.88 at 980 nm wavelength) and band gap (4.4 eV) are close or identical, respectively, to Ga2O3 bulk properties. Reflectivities as low as 10−5 for Ga2O3/GaAs structures and a small absorption coefficient (≊100 cm−1 at 980 nm) were measured. Dielectric properties include a static dielectric constant between 9.9 and 10.2, which is identical to bulk Ga2O3, and electric breakdown fields up to 3.6 MV/cm. The Ga2O3/GaAs interface demonstrated a significantly higher photoluminescence intensity and thus a lower surface recombination velocity as compared to ...

Ga2O3 films for electronic and optoelectronic applications

Methods for accurate and conformal removal of atomic layers of materials make use of the self-limiting nature of adsorption of at least one reactant on the substrate surface. In certain embodiments, a first reactant is introduced to the substrate in step (a) and is adsorbed on the substrate surface until the surface is partially or fully saturated. A second reactant is then added in step (b), reacting with the adsorbed layer of the first reactant to form an etchant. The amount of an etchant, and, consequently, the amount of etched material is limited by the amount of adsorbed first reactant. By repeating steps (a) and (b), controlled atomic-scale etching of material is achieved. These methods may be used in interconnect pre-clean applications, gate dielectric processing, manufacturing of memory devices, or any other applications where removal of one or multiple atomic layers of material is desired.

Adsorption based material removal process

A method of removing at least a portion of a silicon oxide material is disclosed. The silicon oxide is removed by exposing a semiconductor structure comprising a substrate and the silicon oxide to an ammonium fluoride chemical treatment and a subsequent plasma treatment, both of which may be effected in the same vacuum chamber of a processing apparatus. The ammonium fluoride chemical treatment converts the silicon oxide to a solid reaction product in a self-limiting reaction, the solid reaction product then being volatilized by the plasma treatment. The plasma treatment includes a plasma having an ion bombardment energy of less than or equal to approximately 20 eV. An ammonium fluoride chemical treatment including an alkylated ammonia derivative and hydrogen fluoride is also disclosed.

Methods of removing silicon oxide and gaseous mixtures for achieving same

The invention provides a method for depositing a metal film on a substrate, comprising generating a high density plasma in a chamber, sputtering metal particles from a target to the substrate, and applying a modulated radio frequency (RF) bias to the substrate during deposition. Another aspect of the invention provides an apparatus for depositing a metal film on a substrate comprising a high density plasma physical vapor deposition (HDP PVD) chamber and a controller to modulate a RF bias power applied to a substrate in the chamber.

Step coverage and overhang improvement by pedestal bias voltage modulation

Silicon dioxide on a substrate is directionally etched using a hydrogen halide plasma which is created within an etch chamber. The method selectively etches silicon dioxide relative to polysilicon and silicon nitride. A substrate and the combination of NH 3 and NF 3 gases or the combination of CF 4 and O 2 gases mixed with H 2 and N 2 gases are located within an etch chamber. An electrical field is created within the etch chamber causing the gas mixture to form a plasma. The negative charge at the bottom of the chamber attracts the positively charged plasma, thereby etching the substrate in the downward direction. The result is an anisotropic product. The method is also shown to be effective in non-selectively etching thermal and deposited oxides, resulting in a similar etch rate for the different types of oxides.

Etching of silicon dioxide selectively to silicon nitride and polysilicon

An electron cyclotron resonance plasma reactor has been built in order to study the filling of high aspect‐ratio features on semiconductor devices with metal. The reactor produces a plasma of copper which is nearly 100% ionized at the substrate, without the use of any buffer or carrier gas. The ion flux is dependent on both the feed rate of copper neutrals into the plasma region, and on the microwave power absorbed in the plasma. Solid filling of features having aspect ratios as high as 4.2 is demonstrated, and a simple model is derived to explain the fill characteristics.

Copper deposition by electron cyclotron resonance plasma

Silicon dioxide on a substrate is directionally etched using a hydrogen halide plasma which is created within an etch chamber. The method selectively etches silicon dioxide relative to polysilicon and silicon nitride. A substrate (18) and the combination of NH₃ and NF₃ gases or the combination of CF₄ and O₂ gases mixed with H₂ and N₂ gases are located within an etch chamber (16). A power source (26) is used to create an electrical field within the etch chamber causing the gas mixture (14) to form a plasma. The negative charge at the bottom of the chamber attracts the positively charged plasma, thereby etching the substrate in the downward direction. The result is an anisotropic product. The method is also shown to be effective in non-selectively etching thermal and deposited oxides, resulting in a similar etch rate for the different types of oxides.

Method of plasma etching silicon dioxide, selectively to silicon nitride and polysilicon

An electron cyclotron resonance plasma heating apparatus system and process in which microwave energy is transmitted directly in an axial direction through an evacuated chamber to generate energetic electrons. These energetic electrons spiral around the magnetic field lines formed by the solenoid and spiral substantially parallel to the axis. A metal atom vapor source transmits the metal atom vapor into the chamber through a housing port in the chamber wall. The metal atom vapor source in the housing is out of the line of sight of the substrate. The metal atoms are ionized by the energized electrons, and these ionized metal atoms are confined to the plasma column substantially free of neutral atoms as such ionized metal approaches and contacts the substrate in said evacuated chamber. In this way, the ionized metal atoms substantially avoid contact with the wall of chamber. A sputter target of a second metal may be placed in the plane of the substrate and a bias voltage applied to the target. Atoms of the second metal are then sputtered off and ionized by the plasma and are deposited on the substrate with the first metal ions.

Method and apparatus for filing high aspect patterns with metal

The surface chemistry of GaAs‐oxide removal with an electron cyclotron resonance (ECR) hydrogen plasma has been investigated with x‐ray photoelectron spectroscopy. It is found that As oxide is efficiently removed at room temperature, and heating expedites the removal of Ga oxide. Band bending changes during ECR hydrogen‐plasma oxide reduction are also discussed.

William M. Holber

Papers

Etching of silicon dioxide selectively to silicon nitride and polysilicon

Copper deposition by electron cyclotron resonance plasma

Method of plasma etching silicon dioxide, selectively to silicon nitride and polysilicon

Method and apparatus for filing high aspect patterns with metal

GaAs‐oxide removal using an electron cyclotron resonance hydrogen plasma